HK1098519A1 - Apparatus and method for building support piers from one or successive lifts formed in a soil matrix - Google Patents

Abstract

A method and apparatus for forming a support aggregate pier having compacted aggregate lifts in a soil matrix, includes an elongate, hollow tube with a bulbous leading end bottom head element that is forced or lowered into the soil matrix. The hollow tube includes a mechanism for releasing aggregate from the lower head element of the tube as the tube is lifted in predetermined increments. The same hollow tube is then lowered or pushed in predetermined increments to vertically compact the released aggregate in thin aggregate lifts, while forcing a portion of the compacted aggregate transaxially into the soil matrix at the sidewalls of the cavity. The process may be repeated to form a series of compacted aggregate lifts comprising an aggregate pier or the process may include forming only a single lift for the aggregate pier while densifying adjacent matrix soils and imparting lateral stress in these soils.

Description

Apparatus and method for constructing a pier from one or more continuous intervals formed in a soil matrix

Reference to related applications

This international application was derived from and incorporates U.S. provisional application serial No. 60/513,755, filed on 23/10/2003 under the name "apparatus and method for constructing a buttress from a continuous interval formed in a soil matrix", and U.S. new application serial No. 10/728,405, filed on 12/2/2004 under the name "apparatus and method for constructing a buttress from one or continuous intervals formed in a soil matrix", for which priority has been applied.

Background

The primary aspect of the invention is directed to an apparatus and method for constructing a pier containing one or more compacted aggregate intervals (lifts). The apparatus can form or build single or multiple interval piers in the soil matrix, and can strengthen the soil adjacent to the piers. The apparatus is constructed by applying force to a hollow tube means into a soil matrix, then lifting the hollow tube means to form a cavity in the soil matrix, pouring aggregate through the hollow tube means into the cavity portion of the lower portion of the lifted hollow tube means, and then driving the hollow tube means downwardly to compact the aggregate while laterally forcing it into the soil matrix.

In U.S. patent No. 5,249,892, incorporated herein by reference, a method and apparatus for forming small aggregate buttresses in the field is disclosed. This step involves drilling a cavity in the soil matrix and then introducing and compacting successive layers of aggregate or aggregate intervals into the cavity to form a pier that can support the building structure. Such piers are constructed by first drilling a hole or cavity in the soil matrix, then removing the drill, and then filling the cavity with a relatively small loose layer of aggregate, which is then impacted or beaten against the aggregate layer in the cavity with a mechanical rammer. The mechanical tamper is typically removed after each layer is compacted and additional aggregate is added to the cavity to form the next compacted layer or interval. The interval or aggregate layer compacted during the pier forming step is typically 2-3 feet in diameter and about 12 inches thick in the vertical direction.

The apparatus and method may provide a rigid and substantially stable column or pier for supporting a structure. The method of forming the pier construction, however, has limitations in depth where more economical and faster methods of forming the pier are also possible. Another limitation is that in certain types of soil, particularly sandy soils, there is a possibility of collapse during the drilling or forming of the cavity and the possibility of using temporary casings, such as steel pipe casings. The use of temporary steel pipe shells severely reduces the production of the buttress and thereby increases the production cost of the buttress. The method described in patent US5,249,892 is also limited to forming piers in limited types of soil whose depth generally does not exceed about 25 feet.

Accordingly, there is a need to develop a buttress construction method and associated machinery that can be continuously and economically utilized to form or construct buttresses at faster installation rates, at deeper depths, in sand or other soils that are unstable when drilled, without the need for temporary casings, and which also has the features and advantages of the small aggregate buttress formation method, equipment and structure disclosed in U.S. Pat. No. 5,249,892.

Disclosure of Invention

Briefly, the present invention relates to a method of installing a pier comprised of one or more layers of aggregate or profiled aggregate segments, with or without additional aggregate, the method comprising the steps of positioning or pushing an elongated hollow tube with a specially shaped lower end head member and a unique tube configuration, or the aggregate is forced into the soil matrix, the aggregate is filled into the hollow pipe comprising the lower end head part, releasing a predetermined volume of aggregate from the lower head member upon raising the hollow tube a predetermined increased distance within the cavity formed in the soil matrix, subsequently applying an axially static vector force and an arbitrarily dynamic vector force on the hollow tube, the special lower end head component transmits energy to the top of the layer section releasing aggregate through the lower end of the hollow pipe, thereby compacting the layer segments of aggregate and also forcing the aggregate laterally or laterally into the sidewalls of the cavity. After lifting the hollow tube with the special lower end member, the compacted aggregate is pushed downwards by axial or vertical static vector force and arbitrary dynamic vector force, during compaction the aggregate is not isolated from the side walls of the cavity by the hollow tube, whereby the aggregate becomes compact and dense, and during the application of lateral forces on the aggregate and the soil matrix, the aggregate enters the soil matrix due to the laterally outward forces. The compacted aggregate thus forms an "interval" typically having a transverse dimension or diameter greater than the diameter of the cavity formed by the hollow tubes and the head piece, the pier being formed of one or more intervals.

When the special lower head member is lifted, aggregate is released from the special lower head member of the hollow tube, preferably following a predetermined incremental procedure, first above the bottom of the cavity, and then above the top of each successive pier segment that has been formed in the cavity and the adjacent soil matrix. After the hollow tube is lifted to expose a part of the cavity while the aggregate is released into the exposed part of the cavity, the aggregate released from the hollow tube is compacted by the pressing force transmitted from the hollow tube and the special head member. The hollow tube is then subjected to a downward force to compact the aggregate and push it laterally into the soil matrix. The aggregate is thereby compacted to predetermined successive increments, or into intervals. This process is repeated continuously along the length or depth of the cavity, resulting in the formation of aggregate piers or pillars in the soil matrix, comprised of independently compacted intervals or layers. In this manner, piers of 40 feet or more in length can be constructed in a relatively short period of time without the need to remove the hollow tubes from the soil. The cross-sectional dimension of the resulting buttress may also be larger than the dimension of the hollow tube.

Various types of aggregates may be used in applying the method, including various types of crushed stone, crushed concrete from quarries or recycled. The additive may comprise water, dry cement, or a slurry, such as a cement slurry, mortar, fly ash, hydrated lime or quicklime, or other additive that improves the load bearing capacity or technical characteristics of the formed pier. Combinations of the above materials may also be used in the process.

The hollow tube with the special bottom head member is positioned in the soil matrix by applying axial and vertical vector static forces and any dynamic vector forces pushing and/or vertically vibrating or vertically impacting the hollow tube with the front end and the special bottom head member into the soil. Soil displaced by initially forced, pushed and/or vibrated hollow tubes with their particular lower head member is generally moved laterally and compacted into the prior soil matrix while being compacted downwardly. If a hard or dense layer of soil is encountered, a cavity or channel may be formed by drilling or pre-drilling the hard or dense layer of soil into which the drive hollow tube and special lower head member may be placed.

The hollow tube is typically formed from a tube of the same diameter and a spherical lower head member and may include an internal valve mechanism near or within the lower head member or at the lower end of the head member. The hollow tube is generally cylindrical and has a constant, uniform, smaller diameter along the upper section of the tube. The spherical or larger outer diameter lower end of the hollow tube (i.e., the lower head member) is formed integrally with the hollow tube or is formed separately from and attached to the reduced diameter lower end of the hollow tube. That is, the lower tip member is also generally cylindrical, having a larger outer diameter or outer cross-sectional configuration than the remainder of the hollow tube, and is coaxial with the central axis of the hollow tube. The front end of the lower head member is shaped to facilitate penetration into the soil matrix and to transmit the required vector forces into the surrounding soil and also into the aggregate released from the hollow tube. The transition from the smaller outer diameter portion of the hollow tube to the lower head member may be frusto-conical. Similarly, the bottom of the head member may be frusto-conical or conical to facilitate penetration and compaction of the soil. The forward end of the lower head member may include a sacrificial cover member that penetrates the soil substrate on which the hollow tube is initially placed into the soil while preventing soil from entering the hollow tube. The sacrificial cover is then released from the end of the hollow tube when the hollow tube is first lifted to expose the end passage so that aggregate can flow into the cavity formed by the lifting of the hollow tube.

Additionally, the front end of the lower head member may also include an outlet passage with a mechanical valve that is closed during initial penetration of the soil matrix by the hollow tube and lower head member, but is open during its lifting to release aggregate. Other types and shapes of nose valve mechanisms may be utilized to facilitate penetration of the initial soil matrix, release of aggregate as the hollow tube is lifted, and to facilitate the transfer of vector forces in conjunction with the nose or lower head member to compact successive intervals.

In addition, the apparatus includes means for positioning the lift anchor member in the formed pier and indicating means for measuring the amount of movement of the bottom of the formed pier under load, for example during load testing. These assist features or devices are installed in the hollow tube during the formation of the buttress.

It is therefore an object of the present invention to provide a hollow tube with a specially designed lower end head member, with or without attachments, for forming a compacted aggregate pier that can extend to greater depths, and to provide an improved method for forming a pier that extends to greater depths than are typically achieved in the prior art with small aggregate piers.

It is another object of the present invention to provide an improved method and apparatus for forming a compacted aggregate pier that does not require the use of temporary steel shells during the formation process, particularly in soils that are prone to slump, such as sandy soils.

It is another object of the present invention to provide an improved method and apparatus for forming a pier of compacted aggregate that may contain any additional material with the aggregate and forming pier, including stone mixes, additional water, additional dry lime, additional cement slurry, additional cement mortar, additional fly ash, additional quicklime or hydrated lime, other types of additional material that can enhance the soil matrix characteristics.

In addition, another object of the present invention is to provide an aggregate pier structure which can be installed in various types of soil and also can be deeper and faster than the prior art aggregate pier structure.

It is another object of the invention to provide a pier forming apparatus for quickly and efficiently forming a compacted multiple layer pier and/or a pier containing a single layer pier.

Other objects, advantages and features of the present invention will be described in detail below.

Drawings

The invention is described in detail below with reference to the attached drawing figures, wherein:

FIG. 1 is a schematic illustration of a hollow tube with a lower end member forced or driven into the soil by vertical static vector forces and any dynamic forces;

FIG. 2 is a schematic representation of the sequential steps of FIG. 1, wherein aggregate is placed in a funnel and into a hollow tube;

FIG. 3 is a cross-sectional view of a funnel having two independent dampers and which may be used in combination with a hollow tube;

FIG. 3A is a cross-sectional isometric view of the funnel and hollow tube of FIG. 3;

FIG. 3B is a cross-sectional isometric view of the funnel and hollow tube of FIG. 3;

FIG. 4 is a schematic cross-sectional view of a hollow tube with an internal clamp or check valve;

FIG. 5 is a schematic illustration of the step of selectively introducing water, cementitious slurry or other additional material into a hollow tube having a tank of recycled water or slurry;

FIG. 6 is a schematic representation of a step following FIG. 2 in which the hollow tube and lower head member are raised to a predetermined distance to temporarily expose the cavity in the soil matrix so that aggregate quickly fills the exposed cavity;

FIG. 7 is a schematic representation of the step following step 6 wherein the bottom valve in the lower portion of the hollow tube is opened to release aggregate into the unmasked area or cavity portion;

FIGS. 8A and 8B are cross-sectional views of another apparatus and process depicted or illustrated in FIG. 7, wherein the lower end member of the hollow tube includes a sacrificial cover that is placed into the bottom of the forming cavity in FIG. 8B;

FIG. 8C is a cross-sectional view of the sacrificial cover of FIG. 8B as seen along section line 8C-8C in FIG. 8B;

FIG. 9 is a schematic view of a hollow tube and its accompanying special lower head member providing vertical, static and arbitrary dynamic vector forces to move the hollow tube and lower head member downward a predetermined distance by impacting and compacting aggregate released from the hollow tube and by pushing the aggregate laterally into the soil substrate;

FIG. 10 is a schematic illustration of a hollow tube and its particular lower head member elevated a predetermined distance to form a second interval;

FIG. 11 shows a schematic view of operating the hollow tube and lower head member to provide a vertical vector force to move the hollow tube and lower head member downward a predetermined distance to form a second compacted interval on top of the first compacted interval;

FIG. 12 shows a schematic view of a hollow tube with any rebar rod components or indicator members attached to a panel mounted inside a pier;

FIG. 13 is a schematic illustration of a hollow tube wherein any water or cement mortar is mixed in the hollow tube with aggregate;

FIG. 14 is a vertical cross-sectional view of a particular lower header member with a trapdoor-type base valve;

FIG. 15 is a cross-sectional view of the lower header member of FIG. 14 as viewed along line 15-15;

figure 15A is a partial cross-sectional view of another lower header member of the type shown in figure 14;

FIG. 16 is a cross-sectional view of a particular lower header member with a lossy cap at the lower end similar to FIG. 8A;

FIG. 17 is a cross-sectional view of a particular lower head member with any lifting anchor members or indicating devices attached to the plate;

FIG. 18 is a cross-sectional view of a partially formed multi-segment pier formed from hollow tubes and a special lower end member and method of the present invention;

FIG. 19 is a cross-sectional view of a fully formed multi-segment pier formed from hollow tubes and a special lower end member and method of the present invention;

FIG. 20 is a cross-sectional view of a plurality of formed segment piers with optional reinforcing bars connecting the plates to enable the formed pier to incorporate lift anchor piers or to incorporate indicating devices for continuous load testing;

FIG. 21 is a cross-sectional view of a formed pier preloaded or modulus-indicating load testing on a completed pier;

FIG. 22 is a graph of the load test of the buttress of the present invention in the formation of the same soil matrix as compared to a drilled concrete buttress;

FIG. 23 is a cross-sectional view of a method of forming a single-interval pier or pier using the apparatus of the present invention, in which one or more intervals may be formed after lifting the apparatus an extended distance from the bottom of the initial cavity formed in the soil matrix by the apparatus;

FIG. 24 is a cross-sectional view of a structure formed by the method of FIG. 23;

FIG. 25 is a cross-sectional view of a further successive step of the step shown in FIG. 24;

fig. 26 is a cross-sectional view of a further sequential step of the method of fig. 22-24.

Detailed Description

General structure

FIGS. 1, 2, 5, 6, 7, 9, 10, 11, 12, 13, 18, 19, 20 and 23-25 illustrate the general overall structure of a buttress forming apparatus or machine, as well as additional sequential steps in the practice of the method of forming the final composite buttress structure of the present invention. Referring to fig. 1, the method is used to place a pier on a soil substrate that requires strengthening the soil to make it harder or stronger. The present invention actually requires a variety of soil classes, particularly sand and clay soil. The present invention can utilize aggregate, and optionally aggregate with additional materials such as cement mortar, to build pier structures including one or more risers that are stiffer and stronger than many prior art aggregate piers and can be economically extended or built to greater depths than many prior art piers, which can be formed without the use of temporary steel shells unlike many prior art piers, and which can be installed more quickly than many prior art piers.

In a first step, a hollow tube or shaft 30 with a longitudinal axis 35, including or carrying a special lower head member 32 and an associated upper hopper 34 for aggregate, is driven into a soil matrix 36 by a static axial vector force drive device 37 as shown in fig. 3 and optionally vertically (axially) vibrated or punched or both by dynamic vector forces. A portion of the soil matrix 36 containing a quantity of material displaced by pushing on the length of the hollow tube 30 including the particular lower head member 32 is subjected primarily to lateral forces thereby compacting the adjacent soil matrix 36. As shown in FIG. 1, the hollow tube 30 may comprise a cylindrical steel tube 30 having a longitudinal axis 35, for example, with an outer diameter of 6-14 inches. In the event that a layer of hard or high density soil blocks the hollow tube 30 and the particular lower head member 32 from being pushed into the soil matrix 36, such hard or high density layer may be drilled or pre-drilled and the pushing process may continue using the drive device 37.

Generally, the hollow tube 30 has a uniform cylindrical shape, although other shapes may be used. Although the outer diameter of the hollow tube 30 is typically 6-14 inches, other diameters may be used in the practice of the invention. Generally hollow tube 30 may also be extended or pushed to the final depth of the pier in soil matrix 36, for example up to 40 feet or more. The hollow tube 30 is typically secured to an upper end drive extension 42 which may be gripped by a drive device or machine 37 to push the hollow tube 30 in and optionally vibrate or impact into the soil matrix 36. The hopper 34 containing the aggregate container 43 is generally isolated from the extension member 42 by isolation dampers 46, 48. The vibration or impact member 37 fastened to the extension member 42 is supported by a cable or an excavator arm or a crane. The weight of the funnel 34, the impact or vibration device 37 (with any additional weight) and the hollow tube 30 are sufficient to provide a static force vector, eliminating the need for a separate static force drive mechanism. The static force vector may be optionally augmented by vertical vibration and/or impact dynamic force mechanisms.

Figures 3, 3A and 3B illustrate preferred features more particularly associated with the funnel 34. Dual isolation dampers 46, 48 are secured to the upper and lower sides of the funnel 34 to reduce vibration created by the funnel 34 and provide a more structurally integrated funnel assembly. The extension member 42 is secured to the hollow tube 30 to transmit static and dynamic forces to the hollow tube 30. The extension member 42 is isolated from the funnel 34 and is thus slidable relative to the dampers 46, 48.

Fig. 4 illustrates any feature of the hollow tube 30. A restrictor, pinch valve, check valve or other type of valve mechanism 48 may be mounted in the hollow tube 30 or in a special lower head member or lower end portion 32 of the hollow tube 30 to partially or entirely close the interior passage of the hollow tube 30 and block or control the flow or movement of the aggregate 44 and optionally add material. The valve 48 may be opened mechanically or hydraulically and may be partially opened or closed in order to control the movement of the aggregate 44 through the hollow tube 30. It may also be operated by gravity in the manner of a check valve that opens the valve when lifted above the aggregate 44 and closes the valve when dropped below the aggregate 44.

Fig. 14 shows the structure of a particular lower end piece or section 32. The particular lower head member 32 is cylindrical, although other shapes may be used. Typically, the outer diameter of the particular lower head member 32 is greater than the nominal outer diameter of the upper section of the hollow tube 30, which is 10-18 inches, although other diameters and/or cross-sectional configurations may be used in the practice of the present invention. That is, the end member 32 may have the same or a smaller cross-sectional dimension than the hollow tube 30, but such a configuration is generally not preferred.

Fig. 14, 15 and 15A show an embodiment of the present invention having a valve mechanism incorporated in the head member 32. The tip member 32 has a frustoconical bottom section or base 50 with a discharge opening 52 for aggregate 44 that opens or closes when a valve plate 54 uncovers or covers the discharge opening 52. The valve plate 54 is mounted on a rod 56 which slides in a socket 59 held in place by radial struts 58 attached to the wall of the inside passage of the head piece 32 of the hollow tube 30. Valve plate 54 slides to a closed position when hollow tube 30 is forced down into soil matrix 36 and slides to an open position when hollow tube 30 is raised, thus allowing aggregate 44 to flow. The opening of the valve plate 54 is controlled or limited by a rod 56 having a head 56a that limits the sliding of the rod 56. The hollow tube 30 can thus be driven to the desired depth 81 (fig. 6), with the discharge opening 52 being closed by the valve plate 54. The hollow tube 30 is then lifted (e.g., distance 91 shown in fig. 10), the valve plate 54 extends downward due to gravity, and the aggregate 44 flows through the discharge opening 52 into the cavity formed by the lifting of the hollow tube 30. The hollow tube 30 is then impacted or driven downward to close the valve plate 54 and compact the released material to form a compacted interval 72. In the embodiment shown in fig. 14, 15, and 15A, valve plate 54 moves in response to gravity. The rod 56 may be replaced by a fluid driven device, mechanical or electronic mechanism, to replace gravity or assist in its movement. And as described below, valve plate 54 may be replaced by a sacrificial cover or lift anchor as described below or the base plate of indicator device 70. The check valve 38 of fig. 4 may also be used in place of the valve mechanism shown in fig. 14, 15, and 15A.

Typically, the inner diameters of the hollow tube 30 and the end piece 32 are the same or equal, although the outer diameter of the end piece 32 is typically larger than the outer diameter of the hollow tube 30. Also, when a valve mechanism 54 is employed, the internal diameter of the tip member 32 may be greater than the internal diameter of the hollow tube 30. The end member 32 may be formed integrally with the hollow tube 30 or may be formed separately and bolted or welded to the hollow tube 30. Typically, the inner diameter of the hollow tube 30 is 6-10 inches and the outer diameter of the tip member 32 is about 10-18 inches. The opening 53 in fig. 14 at the extreme lower or leading end of the tip member 32 may be equal to or less than the inner diameter of the tip member 32. For example, referring to fig. 14, the tip member 32 may have an inner diameter of 12 inches and the opening 53 may have a diameter of 6-10 inches, while in fig. 16, the discharge opening of the tip member 32 may have the same diameter as the inner diameter of the tip member 32 and the inner diameter of the hollow tube 30 for the sacrificial cover described in the later embodiments.

Valve plate 54 may also be configured to facilitate closure when hollow tube 30 is pushed down into soil matrix 36 or against aggregate 44 in the formed cavity. For example, the diameter of valve plate 54 may exceed the diameter of opening 53 in FIG. 14, or the edge 55 of the valve plate may have a bevel as shown in FIG. 15A to mate with beveled edge 59 of opening 53. Valve plate 54 is then held in a closed position in opening 53 when a static or other downward force is applied to hollow tube 30.

The spherical lower head member 32 of the hollow tube 30 generally has a length that is 1-3 times its diameter or largest transverse dimension. As the hollow tube 30 is threaded or forced into the soil, the tip member 32 exerts an increased lateral compaction force on the soil substrate 36, thereby facilitating the passage of the smaller diameter portion 33 of the hollow tube 30 therethrough. The frusto-conical or beveled leading and leading edges 50, 63 of the tip member 32 facilitate downward or driving penetration and, due to their contoured shape design, facilitate lateral compaction of the soil matrix 36. The beveled leading edge 63 in fig. 14 facilitates the lifting of the hollow tube 30 and tip member 32, as well as lateral compaction of the soil matrix 36 during lifting. The shape or angled configuration of the end member 32 may also produce this effect. The leading and guide edges 50, 63 are generally formed at a 45 deg. or 15 deg. angle to the longitudinal axis of the hollow tube 30.

Fig. 5 shows another feature of the hollow tube 30. An inlet 60 and an outlet 62 are provided in the lower portion of the hopper 34 or in the upper end of the hollow tube 30 to allow water or slurry, such as cement mortar, to be added as an aggregate additive component for a particular pier construction. The function of the outlet 62 is to maintain a level of water or additional components where the flow of aggregate can be effectively facilitated, and also to recirculate slurry from the storage tank back into the storage tank, facilitating mixing and maintaining a relatively constant head or head (pressure) of the slurry. The inlet 60 and outlet 62 may be directed into the funnel 34 or hollow tube 30 (see fig. 13), or may be connected to the tip member 32 with separate channels or conduits. It should be noted that a slurry discharge port 31 is provided through the hollow tube 30 above the end piece 32 as shown in fig. 2 to deliver the discharged slurry to the surrounding annular space of the hollow tube 30 and to prevent soil of the soil matrix 36 from filling the cavity.

Figures 8A, 8B, 8C and 16 show additional features of lower head member 32. A sacrificial cap 64 is provided at the bottom or lower portion of the slide valve 54 to prevent the head member 32 from becoming clogged when the head member 32 is pushed downward into the soil substrate 36. The configuration of the cover 64 may be any shape. For example, may be flat, pointed or beveled, and may be curved. When it is a bevel shape, it is at an angle of 45 deg. or 25 deg. to the horizontal axis 35. The cover 64 may include a plurality of outwardly biased feet 87 positioned to fit within the central opening 89 of the lower head member 32 and hold the cover 64 in place until the hollow tube 30 is first lifted and the aggregate 44 flows out of the opening 52 into the exposed cavity section.

Figure 17 illustrates another feature of a particular lower head member 32. The slide plate 54 and the rods 56 for the support plate 54 may include channels or axial tubes 57 that allow the reinforcement members or rods 68 to be connected with the base plate 70. The bar 68 and plate 70 are released at the bottom of the formed cavity and are used as lift anchors or indicating devices to measure the amount of pier bottom movement during the load test. A sliding rod 68 attached to a base plate 70 may replace the sacrificial cover 64, close the opening of the special head piece 32 during pushing into the soil substrate 36, and may serve as a platform for mounting a lift anchor or indicating device. The bottom valve plate 54 can thus be omitted or held in place while the lifting anchors or indicating devices are applied. Fig. 20 shows that at the buttress formed with the present invention, lift anchors 68, 70 or indicating devices are provided, with the plate or valve 54 omitted.

Method of operation

Fig. 1 shows a typical first step in operating the device or apparatus. With a special end member 32 attached to upper extension member 42 and hollow tube 30 attached to funnel assembly 34, vertical or axial static vector forces are exerted by the weight of drive means 37 or component parts, generally enhanced by dynamic vector forces, into soil matrix 36. In use, a vector force of 5-20 tons is always applied to the hollow tube 30 with the particular end member 32 of the above size and configuration. Figure 2 shows the placement of aggregate 44 into the hopper 34 when the hollow tube 30 and its attachment have reached the planned depth 81 of the pier into the soil substrate 36. Fig. 6 shows subsequent upward and lifting movement of hollow tube 30 by a predetermined lift distance 91, typically 24-48 inches, to expose a portion of cavity 102 in soil matrix 36 below lower head member 32.

Fig. 7 shows the bottom valve 54 being opened to allow the aggregate 44 and any additives to fill the space or portion 85 of the cavity 102 below the particular head piece 32 while the hollow tube 30 and its accessories are lifted. When the hollow tube 30 is lifted by the gravity of the aggregates 44 on the top side of the valve 54, the valve 54 can be opened. Alternatively, the valve 54 may be actuated by, for example, a hydraulic mechanism, or the hollow tube 30 may be raised and aggregate added therewith and operated by the valve 54 to flow through the valve opening 53. The internal valve 38 may furthermore be opened during or after the lift. Without the valve 54, the sacrificial cover is released from the end of the head piece 32 by the force of the aggregate 44 passing directly through the hollow tube 30 when the particular head piece 32 is lifted from the bottom 81 of the formed buttress cavity 102.

Fig. 9 shows that the hollow tube 30 and the appendages are then pushed downward in the soil matrix 36 and the bottom valve 54 is closed to compact the aggregate 44 in the cavity portion 85, thereby subjecting the aggregate 44 and any appendages to lateral and vertically downward forces. To form a complete interval 72 that is 1 foot thick after the predetermined lift distance 91 of the hollow tubes 30, the predetermined travel distance of the downward push is generally equal to the lift distance 91 minus 1 foot. The design thickness of the interval 72 may not be limited to 1 foot depending on the requirements of the particular shaped pier and the technical characteristics of the soil matrix 36 and aggregate 44. In the application of the present invention as shown in fig. 7, it is important to compact the aggregate 44 released into the vacated cavity portion 85 to horizontally affect lateral movement as well as vertical compaction of the aggregate 44.

Fig. 10 shows the next or second interval being formed by lifting the hollow tube 30 and its attachment another predetermined distance 91A, typically 24-48 inches, to open the bottom valve 54 (in the embodiment using valve 54) and allow passage or movement of the aggregate 44 and any additives into the cavity portion 85A that is opened or exposed by lifting the hollow tube 30.

Typically lowered (as described above) after the hollow tube is raised 2-4 inches to form the buttress layer segment 72, typically having a vertical dimension of 1 inch to form the buttress forming material described above. The axial dimension of the interval 72 may be 3/4-1/5 of the hollow tube 30 lift distance 91. However, FIGS. 23-26 also depict forming another compaction schedule.

Fig. 11 shows the hollow tube 30 and its attachment pushed downward and the valve 54 at the bottom closed to compact the aggregate 44 in the newly exposed cavity portion 85A shown in fig. 10 and apply a lateral force to the aggregate 44 and any additives to enter the soil matrix 36. The distance pushed is equal to the lift distance minus the designed interval thickness. When the sacrificial cover 64 is employed, the bottom opening 50 can be kept open while the aggregate 44 is compacted.

Fig. 18 shows the pier partially formed by the above steps, in which multiple intervals 72 are sequentially formed by compaction, and the hollow tube 30 is lifted as the aggregate 44 fills the cavity portion 85X, and fig. 19 shows the pier 76 fully formed by the above steps. Fig. 20 shows a formed buttress 76 with lift anchors 68, 70 or indicating devices. Figure 21 illustrates the step of any preloading on a formed pier 76 by placing, for example, a weight 75 on the pier, and performing any indicator modulus tests on the formed pier 76 containing multiple compacted intervals 72.

Figures 23-26 show another version of the pier formed using the apparatus. The hollow tube 30 is initially forced or driven into the soil substrate 36 to a desired depth 100. The lowermost end of the head member 32 includes the valve mechanism 54, a sacrificial cover 64, and the like. Force is applied vertically downward on the hollow tube 30 into the soil-forming cavity 102 (fig. 23). Given that a particular lower head member 32 is generally cylindrical, cavity 102 is generally cylindrical, and may or may not maintain a full diameter configuration associated with the shape and diameter of lower head member 32.

The hollow tube 30 is advanced to the desired penetration into the soil substrate 36 (fig. 23) and the hollow tube is lifted to the top of the formed cavity (fig. 24). As the hollow tube is lifted, the aggregate 44 and any additional material are discharged from under the bottom end of the particular lower header member 32.

Generally, additional material may be removed into the annular space 104 between the upper portion 33 of the hollow tube 30 and the inner wall of the shaped cavity 102. It should be noted that additional material may flow through the secondary side passage 108 or the supplemental conduit 110 in the hollow tube 30. When the hollow tube 30 is lifted, the cavity 102 is filled. And when the particular lower head member 32 is lifted, additional material in the annular space 104 is forced outwardly into the soil matrix 36 due to its configuration.

The hollow tube 30 thus substantially elevates the entire length of the initially formed cavity 102, and then as shown in fig. 25, again applies a downward force to compact and laterally force the material in the cavity 102 into the soil matrix 36 (fig. 25). The degree of downward movement of the hollow tube 30 depends on various factors including the size and shape of the cavity 102, the composition and mixing ratio of the aggregate and its additional materials, the force exerted on the hollow tube 30 and the characteristics of the soil matrix 36. The generally downward movement continues until the lower end or bottom end of the particular lower header member 32 is at or near the bottom 81 of the previously-formed cavity 102.

After the second downward movement is completed, the hollow tube 30 is lifted generally the full length of the cavity 102, and during the lifting the aggregate and any additional material is again discharged and again filled to re-form the cavity 102A (fig. 26). This cycle of at least fully downward and fully upward movement is performed at least twice, and preferably three or more times, to force more aggregate 44 and any additional material thereof laterally into soil matrix 36. In addition, the cycle may be adjusted in various modes, such as full lift and partial drop or full lift and drop after partial lift and full drop, or a combination thereof.

Brief introduction to considerations

The aggregate 44 may be facilitated to flow and feed through the hollow tube 30 by water or slurry or other fluid. Water may be fed directly into the hollow tube 30 or through the funnel 34. Pressure or head can be provided by using the funnel 34 as a reservoir. Whereby the water, slurry or other fluid is effective to cause the aggregate to flow particularly within a hollow tube 30 of small diameter, for example, a hollow tube 30 of 5-10 inches in diameter. It should be noted that for all of the described embodiments, the size of the passages and/or discharge openings in the hollow tube 30 is at least 4 times the maximum size of the aggregate. Water is particularly desirable as a lubricant when the vertical height of each interval 72 is about 12 inches and the internal diameter of the hollow tubes 30 is about 6-10 inches.

It should be noted that the diameter of cavity 102 formed in soil matrix 36 is much smaller than many other pier forming techniques. However, by utilizing a relatively small diameter cavity 102 or small diameter opening into the soil matrix 36, the hollow tube 30 can be forced or driven into greater depths and thereby form a pier having a horizontal dimension that is much greater than the outer dimension of the hollow tube 30. As described above, by compacting aggregate 44 with or without additional material including fluid material, one or more intervals may be formed, and horizontal displacements may be formed by hollow tube 30 and special lower head member 32. The vertical compaction of layer segments 72 and the application of force laterally to the aggregate results in the formation of a highly coherent pier structure.

Test results

FIG. 22 shows the test results of the pier of the present invention compared to a drilled concrete pier. The graph shows the motion of three buttress configurations of the present invention (curves a, B, C) and the motion of a prior art drilled concrete buttress (curve D) with the buttress increasing from an increasing load up to a maximum load with the rear fork decreasing the load down to zero load. The following test conditions were used for the tests, and the drilled reinforced concrete buttress was used as the control test buttress.

A hole or cavity of approximately 8 inches in diameter is drilled to a depth of 20 feet and filled with concrete to form a drilled concrete buttress (test D). Reinforcing steel bars are placed in the center of the bored concrete pier to provide structural integrity. A 12 inch diameter cylindrical piece of cardboard was placed on top of the buttress to facilitate the following pressure load test. All four tested soil matrices were medium density fine to medium grain sand with standard air blast counts (SPT's) of 3-17 per foot of air blast. Groundwater was added at a depth of about 10 feet below the ground.

From the reports in tests a, B, and C, the aggregate pier of the present invention is made from a hollow tube 30 having an outside diameter of 6 inches with a special lower head member 32 having an outside diameter of 10 inches. Tests a and B use aggregate only. Test C utilized aggregate and cement slurry. Test a used a predetermined 2 foot lift motion and a predetermined 1 foot push down motion to result in multiple 1 foot intervals. Test B used a predetermined 3 foot upward movement and a predetermined 2 foot downward movement resulting in a 1 foot interval. Test C used a predetermined 2 foot upward movement and a predetermined 1 foot downward movement with additional cement slurry contained therein.

The data analysis relates to the stiffness or modulus of the constructed buttress. At 0.5 inch deflection, test A corresponds to a load of 27 tons, test B corresponds to a load of 35 tons, test C corresponds to a load of 47 tons, and test D corresponds to a load of 16 tons. Thus at this deflection (0.5 inch), test B was compared to the base using test B as a standard test, with a ratio of 1.0 for test B to hardness, 0.77 for test A, 1.34 for test C, and 0.46 for test D. The hardness of the standard part test B was 2.19 times that of the control test abutment test D. The hardness of the standard part test B was 1.30 times that of test a and the hardness of test C with the additional slurry was 2.94 times that of the prior art concrete buttress (test D). This shows that the modulus of the buttress of the present invention is much higher than the modulus of the drilled reinforced concrete buttress (test D). These tests also show that the step with 3 foot lift and 2 foot push down is much harder than the step with 2 foot lift and 1 foot push down. The test also shows that the application of the cementitious additive slurry sufficiently increases the hardness of a formed pier having a deflection of less than about 0.75 inches, but does not sufficiently increase the hardness of a formed pier having a deflection of greater than about 0.9 inches as compared to test B.

In the preferred embodiment, the hollow tube or quill 30 has various advantages due to its larger cross-sectional area at the lower head member 32. First when the bottom valve mechanism 54 is employed, and when the hollow tube 30 is partially withdrawn from the soil substrate 36 to expose or form the cavity 85 in the soil substrate 36, the configuration of the apparatus may reduce the chance of clogging of aggregate in the apparatus during formation of the cavity 102 in the soil substrate 36. In addition, this configuration may extract additional energy from the static and dynamic force vectors to impact through the lower head member 32 of the apparatus and onto the aggregate 44 in the cavity 70. Another advantage is that because the effective diameter of the hollow tube 30 is smaller than the effective diameter of the lower head member 32, the friction of the hollow tube 30 against the sides of the subterranean formation cavity 102 is reduced. That is to say reducing the remaining cross-sectional area of the hollow tube 30. This may allow for quick penetration into the soil and may allow for penetration into a more rigid or sturdy structure. The larger cross-section head piece 32 also enhances the ability to provide a cavity portion 102 that receives aggregate 44 that is larger in volume than the remainder of the associated hollow shaft 30, whereby additional aggregate can receive longitudinal (or axial) and transverse (or transaxial) forces when forming the interval 72. The reduced friction of the hollow tubes 30 on the sides of the shaped cavities 102 in the soil matrix 36 also provides the advantage of allowing the hollow tubes 30 to be lifted more easily during the formation of the pier.

In the steps of the present invention, the lowermost interval 72 may have a larger effective diameter, and may also have varying amounts of aggregate therein. Thus, when forming the foundation of the pier 76, the lower or lowermost layer segment in the pier 76 can have a larger cross-sectional area and depth profile. In other words, for example, by lifting the quill 30 to 3 feet, then reducing the height of the interval 72 to 1 foot, the lower or lowermost interval may be increased, whereas by lifting the quill 30 to 2 feet, then reducing the thickness of the interval 72 to 1 foot, the next interval 72 may be formed.

As described above, the completed buttress 76 may be pre-loaded 75 (fig. 21) with a static load or a dynamic load applied to the top of the buttress 76 for a period of time after formation. Whereby the load 75 can be applied to the top of the abutment 76 for 30 seconds to 15 minutes or more. The application of force may also provide a "modulus indication test" since the static load is applied on top of the buttress 76 and deflection measurements under the static load 75 may be performed simultaneously. The modulus indication test and the preloading of each buttress are combined to achieve the aim of one-arrow double carving, namely (1) preloading is applied; (2) a modulus indication test is performed.

The aggregate 44 used to form the buttress 76 may vary. I.e. clean aggregate stone particles are placed in the cavity 85. These stone grains have a standard diameter of 40mm, less than 5% of the stone grains having a standard diameter of less than 2 mm. The slurry is then introduced into the aggregate formed as described above. The slurry may be added simultaneously with the aggregate 44, either prior to the aggregate or subsequent to the aggregate.

When using a vibration frequency as the dynamic force, the vibration frequency applied to the hollow shaft or tube 30 is preferably between 300 and 300 cycles per minute. The ratio of the various diameters of the hollow tube or shaft 30 to the end member 32 is generally 0.92-0.50. As previously mentioned, the angle of inclination of the base may be between 30 and 60 with respect to the longitudinal axis 35.

Another feature of the present invention is to provide a method of forming a buttress by inserting a hollow tube 30 with a particular lower head member 32 to a predetermined desired total depth 81 of the buttress 76. When aggregate and/or slurry or other fluid is poured into the cavity formed by the lifting tube 30 and special end piece 32, the tube 30 and special end piece 32 are then lifted in continuous motion to the total length of the predetermined pier. When the hollow tube 30 and the special head piece 32 then reach the top of the predetermined buttress, they are again pushed by the static force and are randomly augmented by vertical vibrations and/or hit down against the bottom of the buttress by dynamic force mechanisms. The previously discharged cavity-filling aggregate 44 and/or slurry or other material enters the soil matrix in a transverse axial direction and is moved by moving the hollow tube 30 and the end member 32 downwardly. This step is then repeated, with the hollow tubes 30 and end members 32 raised to the remaining length or depth of the predetermined pier, or to less than each distance, and with the hollow tubes 30 raised, the aggregate and/or fluid material fills the newly created cavity. In this manner, the material forming the pier may comprise an interval or series of intervals, with additional aggregate and any grout and/or other additional material being delivered laterally to the sides of the cavity and into the soil matrix.

It should be noted that the mechanism for carrying out the above-described processes and methods is operated in an accelerated manner. The hollow tube 30 and tip member 32 are driven downward to achieve a relatively rapid effect, for example, 2 minutes or less. Depending on the lifting movement distance and lifting rate, it may take less time to increase the partial or total distance that the hollow tube 30 and the end piece 32 are lifted in the forming cavity. This allows the pier to be formed from soil matrix 36 in a matter of minutes. The method and apparatus of the present invention thus allow for a substantial increase in production speed.

Various modifications and variations of the method and apparatus described are possible without departing from the scope of the invention. Thus, changes may be made in the construction and method of the invention without departing from the spirit and scope of the invention. Other configurations, sizes, cross-sectional shapes and tube lengths of the hollow tube may be used. The shape and use of the particular tip member 32 may also vary. The shape and use of the base valve 54 may also be varied or omitted by using a sacrificial cover. The leading end of lower nose member 32 may be suitably shaped. For example, it may be pointed, conical, blunt, angled, bolted, or any other shape that facilitates penetration of the soil matrix and compaction of the aggregate. The enlarged or spherical end members 32 may be used in conjunction with one or more hollow tubes 30 of various shapes or configurations having an increased outer cross-sectional diameter. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.

Claims (34)

1. An apparatus for forming a multi-segment, compacted pier in a soil matrix, comprising in combination:

an elongated hollow tube having a longitudinal axis, a top material inlet end, an open bottom material discharge end and a first outer surface diameter, and an integral, formed lower head member at the open discharge end, the open discharge end having a second outer surface diameter greater than the first outer surface diameter and being configured to provide a combination of axial and transverse axial components of stress as the hollow tube is lowered, the lower head member being integral with the hollow tube; said lower head member including a front lower end including a generally frustoconical configuration intermediate an outer surface of the lower head member and the bottom discharge opening, and a rear end including a generally frustoconical configuration; and

a lower header member cover covering the bottom discharge opening;

the lower head member with the cap and the hollow tube are shaped for insertion into the soil matrix for effective displacement of the soil as the hollow tube and lower head member and the cap are lowered into the soil matrix to form a cavity in the soil matrix, the cap being at least partially removable from the bottom discharge opening upon subsequent lifting of the hollow tube from the formed cavity to allow material to flow through the bottom discharge opening into the portion of the cavity vacated by the hollow tube and lower head member, the lower head member having a cross-sectional dimension greater than the cross-sectional dimension of the hollow tube to reduce friction on the hollow tube when penetrating into and withdrawn from the soil matrix.

2. The apparatus of claim 1 further comprising a fluid feed mechanism for directing fluid material into the hollow tube and a solid material feed mechanism for feeding aggregate material into the inlet end of the hollow tube.

3. The apparatus of claim 1, including aggregate in the hollow tube;

the hollow tube has a generally circular interior cross-section and further includes an aggregate feeding mechanism connected to the top material inlet end for feeding items of aggregate material into the hollow tube, wherein the minimum dimension of the interior diameter of the hollow tube is at least 4 times the maximum dimension of the largest item of aggregate material within the hollow tube.

4. The apparatus of claim 1 further comprising at least one auxiliary feed tube connected to the hollow tube through an opening in an end of the hollow tube for feeding the fluid material into the hollow tube.

5. The apparatus of claim 1, further comprising a hopper for feeding material into the hollow tube, and at least one auxiliary feed tube connected to the hopper for feeding liquid material into the hollow tube.

6. The apparatus of claim 1, further comprising a passage opening in the hollow tube above the lower head member for allowing fluid material in the hollow tube to flow out of the hollow tube above the lower head member and for allowing fluid material outside the hollow tube to flow into an annulus formed between the hollow tube and the soil matrix.

7. The apparatus of claim 1 further comprising a hopper feed mechanism connected to the top material inlet end of the hollow tube.

8. The apparatus of claim 1, further comprising a funnel and at least one separate damper connecting the funnel to the hollow tube.

9. The apparatus of claim 1 further comprising a force mechanism connected to the hollow tube for providing a downwardly directed force on the hollow tube.

10. The apparatus of claim 1 further comprising a force mechanism connected to the hollow tube for providing a static axial force in a downward direction.

11. The apparatus of claim 1 including a force mechanism for providing a force on the hollow tube selected from the group consisting of a vertical reciprocating force, a vertical oscillating dynamic axial force, and combinations thereof.

12. The apparatus of claim 1, wherein the lid comprises a lossy lid.

13. The apparatus of claim 12 wherein the sacrificial cover comprises a transverse axial plate member for retention at the bottom of the formed pier member.

14. The apparatus of claim 13, wherein the cover further comprises at least one axial rod in combination with the plate member.

15. The apparatus of claim 1, wherein the lower head member and the hollow tube each have a uniform cylindrical cross-section.

16. The apparatus of claim 14, wherein at least one of the rods extends axially from the bottom of the shaped buttress to above ground surface level.

17. The apparatus of claim 1, wherein the lid includes a mechanism for opening and closing the bottom discharge opening to allow material flow from the bottom discharge opening when open and to block material flow from the bottom discharge opening when closed.

18. The apparatus of claim 1, wherein the front lower end provides energy to apply a surface to compact aggregate in the cavity.

19. A method of forming a pier in a soil substrate, comprising the steps of:

(a) forming an elongated cavity in the soil matrix having a base and a longitudinal axis by applying a force on a hollow tube having an open top material inlet end forming a portion of the hollow tube and coincident with its longitudinal axis and an open lower head member with a closure mechanism for selectively closing the hollow tube, the lower head member being configured to provide axial and transaxial vector forces on the soil matrix, the closure mechanism maintaining material discharge from the closed lower head member during formation of the cavity;

(b) raising the hollow tube a first incremental distance within the cavity;

(c) opening the closing mechanism when the hollow tube is lifted;

(d) feeding aggregate through a lower head member of the hollow tube into a cavity portion formed as a result of raising the hollow tube the first incremental distance; and

(e) as the hollow tube is lowered, the aggregate in the cavity is compacted by the shaped lower head member by the axial and transverse axial forces exerted thereon.

20. The method of claim 19, wherein the hollow tube is initially forced a predetermined distance into the soil matrix.

21. The method of claim 19, wherein step b) is a predetermined distance.

22. The method of claim 19, comprising the step of cycling from step b) to step e).

23. The method of claim 19, including the step of closing the closure mechanism prior to the compacting step.

24. The method of claim 19, including the additional step of separately supplying a combination of a fluid material and aggregate to facilitate aggregate flow.

25. The method of claim 24, wherein the fluid material is selected from the group consisting of: water, viscous slurries, bentonite, cement, fly ash and combinations thereof.

26. The method of claim 19, wherein the hollow tubes have the same internal cross-section.

27. The method of claim 19, wherein the lower tip member has an outer cross-section that is greater than an outer cross-section of the remainder of the hollow tube.

28. The method of claim 20 including the step of providing a static force on the hollow tube effective to drive the hollow tube and to compact the aggregate.

29. The method of claim 20 including the step of providing a dynamic axial force on the hollow tube effective to drive the hollow tube and to compact the aggregate.

30. The method of claim 19, comprising the step of cycling from step c) to step e).

31. The method of claim 19, wherein the first incremental distance is equal to a height of the pier being formed.

32. The method of claim 19, wherein the first incremental distance is less than the height of the pier being formed.

33. An apparatus for forming a soil reinforcing pier in a soil matrix, comprising in combination:

an elongated hollow tube having a longitudinal axis, the elongated hollow tube including a top material inlet end coincident with the longitudinal axis thereof, an open lower head member discharge end, the lower head member discharge end having an outer cross-section greater than an outer cross-section of a hollow tube adjacent thereto, thereby forming a bulb portion of the hollow tube, the bulb portion of the hollow tube having an outer cross-section of a shape and size greater than an outer cross-section of a hollow tube adjacent to the bulb portion; and

the spherical end has a surface configured to apply axial and transverse axial forces as the material moves downwardly.

34. An apparatus for forming a soil reinforcing pier in a soil matrix, comprising in combination:

a generally cylindrical, elongated hollow tube having a longitudinal axis, a top material inlet end, an open bottom material discharge end; and

a shaped lower end member attached to the material discharge end and having a passageway therethrough substantially coaxial with said longitudinal axis, said lower head member comprising a discharge opening with a lid, the lid being removable from the discharge opening, said lower head member and hollow tube being shaped for insertion into a soil substrate, when the hollow tube and the lower end head part are lowered into the soil matrix to form a cavity in the soil matrix, to effectively displace the soil, when the hollow tube is subsequently lifted from the bottom of the formed cavity, the lid can be removed from the lower head part discharge opening, said lower head member having a cross-sectional area transverse to the longitudinal axis greater than a cross-sectional area of a hollow tube transverse to the longitudinal axis, said lower head member further comprising a formation proximate the discharge opening, configured to exert both axial and transverse axial forces on the soil substrate when lowered into said soil substrate.