NL1029953C2 - Method is for build of underground construction at least partly below ground water level and involves formation of pit and introduction of at least one foundation component at pit location prior to or after formation of pit - Google Patents

Abstract

The method is for the build of an underground construction at least partly below ground water level and involves the formation of a pit and the introduction of at least one foundation component at the pit location prior to or after the formation of the pit. At least part of the underground construction is attached to the foundation component and the underground construction is lowered into the pit. The structural pit is dug in a wet state, so that the water level in it is the same as the ground water during the installation of the underground construction. After this installation, the underground construction is dewatered. During the installation of the underground construction (1), the water level (21) in the pit (3) - between th eunderground construction and the ground sustaining construction (4) - remains maintained and is accordingly the same as the ground water level (2). Water is entirely or partially pumped away so taht the water level inside and outside the pit remains the same. After the underground construction is wholly formed and lowered into the pit, the space between the piles (7) and columns is filled with grout or other suitable hardened filling material.

Description

METHOD FOR BUILDING AN UNDERGROUND CONSTRUCTION

The present invention relates to a method for constructing an underground structure at least partially below groundwater level, comprising the steps of excavating a building pit, installing foundation elements 10 in the ground at or near the site of excavating the building pit. the construction pit, the stringing of at least a part of the underground construction on the foundation elements, and the lowering of the underground construction in the construction pit.

Such a method is known from DE-OS-23 50 808. Injection anchors are fed into the ground here and the underground construction is threaded onto the anchor rods. The underground construction is pushed into the ground under the construction pit by means of Persians. The injection anchors serve as a safeguard against the upward pressure if the underground structure is lowered beyond the groundwater level, which is below the level of the bottom 20 of the construction pit.

The present invention has for its object to provide an improved method for building an underground construction. The invention relates more specifically to the construction of underground constructions at a high groundwater level, as occurs in Europe and in particular in the Netherlands and Germany, whereby the underground construction will ultimately be situated largely or entirely below the groundwater level. Construction can continue on the underground construction above ground.

To this end, according to the invention, the method of the above-mentioned type is characterized in that the construction pit is wet excavated 1029953 2, so that the water level in the construction pit is equal to the groundwater level during the lowering of the underground construction, and in that after the lowering of the underground construction the underground construction is dewatered.

5 As a result, no watertight floor (underwater floor or injection floor) and watertight wall layer are required to obtain a dry building pit. The underground construction is lowered into a wet building pit and the underground construction is only dewatered after lowering. During the construction and afterwards, the risk of leakage and also the risk of subsidence and / or displacement of the ground surrounding the construction pit and objects on that ground is therefore neither present nor negligible.

Furthermore, the subsurface construction is preferably anchored first to the ground below after being lowered before being dewatered.

According to a preferred embodiment, the underground structure is provided with retaining pipes during the construction and, after lowering the underground structure, tension anchors are installed in the ground underneath the underground construction via the retaining pipes and fixed to the underground construction. The tension anchors are installed from above through the rafters and, for example, fixed to the floor with grout. The tension anchors reduce the required span of the floor, so that this floor can be made thinner or with less reinforcement

A watertight underground structure is preferably built. As a result, it is not necessary to make the building pit itself watertight in advance to prevent the ingress of groundwater from the soil surrounding the building pit after dewatering.

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In a particularly advantageous embodiment of the invention, the underground structure is lowered by letting water into it. With the help of water ballast, the lowering of the underground structure can be controlled. The water to be removed from the construction pit during the lowering of the underground construction can be used advantageously for this.

The underground construction can be built in two ways. According to a first manner, the underground construction is mainly built in advance and subsequently lowered in its entirety over the foundation elements into the construction pit. According to a second way, the underground construction is built on the foundation elements step by step during lowering.

For demarcating the building pit and determining the boundaries between which the soil must be excavated, a soil-retaining structure is installed in the soil for excavating the building pit. These can be soil retaining deep walls, sheet pile walls and / or pile walls. Because the walls only have to be earth-turning, since the construction pit is not dewatered beforehand, they can be relatively short and thin. In special situations the excavation site is excavated under embankments and soil-retaining walls are wholly or partially unnecessary. The walls should only withstand the forces supplied by the soil surrounding the construction pit 25 from the outside. The walls can optionally be anchored to the ground surrounding the construction site.

The foundation element preferably comprises a pole. Examples of piles that can be used are screwed or healed (steel) piles or drill piles with extensions. During the construction 1029953 4 I the foundation element is surrounded by a hollow column (with round, square or rectangular shape) that is watertight with the underground! construction is connected. After lowering the underground construction, the column is fixed to the foundation element with grout or concrete.

After lowering, the space between the underground construction and the (walls and bottom of the) construction pit is filled with filling material, such as sand or gravel. Optionally, sand or gravel can also be introduced under the floor of the underground construction by means of a technique known from sunken tunnels.

Finally, the strung underground construction will be pumped empty.

The invention will be further elucidated with reference to the appended drawings. In the drawings:

Figures 1-5 show schematic views of different stages during the construction of an underground construction below groundwater level.

The following reference numerals are used in the figures. According to the invention, an underground construction 1 is at least partially built below groundwater level 2. To this end, a building pit 3 is formed by a soil retaining structure in the form of walls 4 which are arranged in the ground 5. The walls 4 are, if necessary, anchored to the ground 5 surrounding the construction pit 3 by means of tension anchors 6. At the location of the construction pit 3, one or more foundation elements in the form of piles 7 are provided in the ground 5 (see figure 1).

The construction site is then excavated up to the well floor 8. The well bottom 8 is also the level at which, around and near the floor of the underground construction 1, will lie 1029953. As Figure 2 shows, after wet excavation of the construction pit 3, the water level 21 in the construction pit 3 will be equal to the groundwater level 2.

Figure 3 shows the next step. The 5 posts 7 are extended above groundwater level 2. Hollow columns 9 with brackets 10 attached thereto are arranged around the pole extensions 8. Jack jacks 11 are then placed on the top of the pole extensions 8, which yokes are connected to the brackets 10. The floor 12 is made of the underground construction 1 on the brackets 10. The floor 12 can be built using prefab floor plates or be formed by a floor poured into the work. Next, walls 13 are poured onto the floor 12 and optionally a second floor 14. The thus formed and preferably watertight concrete container is lowered into the water (see figure 4). By completely or partially filling the concrete trough with water, the vertical load required to lower the underground structure 1 can in this way be controlled and limited. The jacks are hereby controlled (with the aid of a computer) on displacement and / or force.

If necessary, the posts 7 can be further extended for the installation of subsequent floors (walls and floors) of the underground construction 1. To this end, the jack heads 11 are removed alternately, new pole extensions 8 are placed and the jack head 11 is replaced. The extension of the posts 7 can take place in phases or in one go.

Instead of building the underground structure 1 during the lowering onto the posts 7, the underground structure 1 can also be built predominantly above ground level 30 and lowered in its entirety over the posts 7 into the construction pit 3.

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During the lowering of the underground structure 1, the water level 21 in the construction pit 3 remains between the underground structure 1 and the soil retaining structure 4, and is therefore equal to the groundwater level 2.

5 Water is pumped in whole or in part to outside building pit 3 or into the underground construction 1, such that the water level inside and outside building pit 3 remains at the same level.

After the underground construction 1 has been completely built and lowered into the construction pit 3, the space between the posts 7 and the columns 9 is filled with grout or other suitable hardening filling material. Via this filling material, the underground structure 1 is fixed to the posts 7. If necessary, retaining tubes 15 are provided in the underground structure 1 in order to be able to install tension anchors in the ground below the construction pit 3 from which the underground structure 1 is fixed. The cavities between the underground, construction 1 and the walls 4 and bottom 18 of the construction pit 3 are filled with sand, gravel or other suitable filling material. Subsequently, the underground structure 1 is pumped empty.

The water level 21 between the underground construction 1 and the walls 4 remains at the level of the groundwater 2, so that walls 4 only have a ground-retaining function 25 at all times. Filling material between the underground structure 1 and the soil retaining structure 4 is applied under water.

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Claims (10)

Method for constructing an underground construction at least partially below groundwater level, comprising the steps of: - excavating a building pit, - arranging at least one foundation element in the ground at or near the excavation of the building pit. building pit, 10. stringing at least a part of the underground construction onto the foundation element, and - lowering the underground construction into the building pit, characterized in that - the building pit is wet excavated, so that the water level in the building pit is equal is at the groundwater level during the lowering of the underground construction, and - after the lowering of the underground construction the underground construction is dewatered. Method according to claim 1, wherein the subsurface structure is first anchored to the ground below after being lowered before being dewatered. 3. Method as claimed in claim 2, wherein the underground construction is provided with retaining pipes and wherein tension anchors are provided in the ground via the retaining pipes and fixed to the underground construction when the underground construction is lowered into the construction pit. 30 1029953 The method of any one of claims 1-3, wherein a watertight underground structure is built. 5. Method as claimed in claim 4, wherein the underground construction is lowered by letting water into it. 6. Method as claimed in any of the claims 1-5, wherein the underground construction is mainly built in advance and is lowered in its entirety over the foundation element in the building pit. 7. Method as claimed in any of the claims 1-6, wherein the underground construction is built on the foundation element stepwise during lowering. 8. Method as claimed in any of the claims 1-7, wherein for excavating the construction pit a soil-retaining construction is provided in the soil that delimits the construction pit 20. 9. Method as claimed in any of the claims 1-8, wherein the foundation element comprises a pile, more in particular a screwed or driven pile or a drill pile with extensions. 10. Method as claimed in any of the claims 1-9, wherein the hollow spaces in the underground construction and / or between the underground construction and the construction pit are filled with filling material, such as sand or gravel. 1029953_