CN115467321B - Multi-cavity steel-concrete composite structure with two walls in one and its construction method - Google Patents

Abstract

The invention discloses a two-wall-in-one multi-cavity type steel reinforced concrete composite structure and a construction method thereof, wherein the construction method comprises the following steps of firstly, flattening a field; step two, constructing a guide wall; step three, preparing slurry; step four, grooving construction; step five, hoisting the multi-cavity type steel structure; step six, pouring underwater concrete; step seven, constructing a second multi-cavity type steel reinforced concrete underground continuous wall; and step eight, repeating the construction until the construction is finished. The invention adopts a mode of pouring concrete into the multi-cavity H (cold-bending C) steel structure, so that the periphery of the concrete is in a three-dimensional compression state under the constraint action of the cavity of the H steel or the cold-bending C steel, and the structural bearing capacity is improved. Meanwhile, the steel plate in contact with the soil body has good waterproof performance, and a waterproof layer is not required to be arranged. Steel structure parts in the multi-cavity H (cold bending C) type steel concrete composite structure can be prefabricated and formed in a factory and then transported to the site, so that the construction period is shortened, and the cost is saved.

Description

Multi-cavity steel-concrete composite structure with two walls in one and its construction method

technical field

The invention belongs to the field of civil engineering, and in particular relates to a multi-cavity steel-concrete composite structure with two walls integrated into one and a construction method thereof.

Background technique

At present, there are mainly two kinds of the most common deep foundation pit enclosure structures: reinforced concrete underground diaphragm wall and steel cement-soil mixing wall. The reinforced concrete underground diaphragm wall adopts a trenching machine on the ground to excavate a narrow and long deep trench along the peripheral axis of the deep foundation pit project under the condition of mud retaining wall. After clearing the trench, hang it in the trench Reinforcement cages, and then use the conduit method to pour underwater concrete to form a unit trough section. In this way, a continuous reinforced concrete wall is built underground as a water interception, anti-seepage, load-bearing, and water-retaining structure. Reinforced concrete underground diaphragm wall has been widely used in the current construction field in our country. It has the advantages of large wall rigidity, high strength, and little disturbance to the surrounding environment during construction. The steel-cement-soil mixing wall uses a multi-axis drilling mixer to drill to a certain depth in the in-situ formation, and at the same time sprays a cement-based strengthening agent at the drill bit to repeatedly mix and mix with the foundation soil. Overlap and overlap one axis (hole) construction, and then insert H-shaped steel as its stress reinforcing material before the cement-soil mixture is hardened, until the cement is hardened, a continuous and complete, non-woven structure with certain strength and rigidity is formed. Seams of underground walls.

The reinforced concrete underground diaphragm wall can be divided into compound wall, laminated wall and single wall according to the connection mode between the enclosure structure and the main structure. Due to the aging of the waterproof material and the construction of the composite wall, the waterproof layer in the wall is damaged, and leakage will occur after the side wall of the main structure is cracked; the waterproof layer of the composite wall is difficult to form a continuous and sealed whole, and the structural integrity is difficult to guarantee; the waterproof effect of a single wall It mainly depends on the quality of concrete pouring, temperature and shrinkage cracks, and the waterproof performance is poor. The reinforced concrete structure still has the problem of cumbersome procedures such as binding steel bars as an enclosure structure. Although the steel cement-soil mixing wall can be pulled out and recycled in the later stage, on the one hand, it increases the engineering quantity and cost. On the other hand, the enclosure structure is only a temporary structure, which is not fully utilized in the later stage, resulting in a waste of underground space. To sum up, the two types of traditional deep foundation pit enclosure structures have the problems of complex construction technology, long period, high cost, large space occupation and insufficient waterproof performance.

Contents of the invention

In order to solve the above problems, the invention discloses a multi-cavity steel-concrete composite structure and method with two walls integrated into one. In order to simplify the construction process and improve the mechanical performance of the enclosure structure, the present invention proposes a multi-cavity H (cold-formed C) steel-concrete composite structure. The multi-cavity H (cold-formed C) steel-concrete composite The method of pouring concrete into the type H (cold-formed C) steel structure makes the surroundings of the concrete under the constraints of the H-shaped steel or cold-formed C-shaped steel cavity in a three-dimensional compression state, thereby improving the structural bearing capacity. At the same time, the steel plate in contact with the soil has good waterproof performance, and there is no need to set up a waterproof layer. Part of the steel structure in the multi-cavity H (cold-formed C) steel-concrete composite structure can be prefabricated in a factory and then transported to the site, which shortens the construction period and saves costs.

To achieve the above object, the technical solution of the present invention is:

A method for constructing a multi-cavity steel-concrete composite structure with two walls in one, comprising the following steps:

Step 1. The site is leveled;

Step two, guide wall construction;

Step 3, preparing mud;

Step 4, groove construction;

Step five, hoisting multi-cavity steel structure:

The multi-chamber shaped steel structure includes several shaped steel units, the shaped steel units are H-shaped steel units (2) or cold-formed C-shaped steel units; the flanges of the shaped steel units are welded and spliced to each other in sequence to form a multi-cavity shaped steel structure with openings at both ends; One end of the multi-cavity steel structure is formed with a horizontal joint, and the other end forms an engaging groove for matching with the horizontal joint; the middle part of the multi-cavity steel structure forms several cavities of the same size;

Step six, pouring underwater concrete:

Concrete is poured using the conduit method, and the number of pipe joints required is determined according to the excavation depth of the groove section. The number of bodies determines the number of required conduits. Each cavity needs to be lowered with a conduit, and the gap between the steel plate and the tank wall of the multi-cavity steel structure also needs to be filled with concrete. When the concrete is poured, first place a water-proof ball in the pipe so that the mud in the pipe can be discharged from the bottom of the pipe when the concrete is poured;

Step 7. Construction of the second multi-cavity steel concrete underground diaphragm wall:

Excavate the second unit groove section; hoist the second multi-cavity steel structure so that the horizontal joint of the second multi-cavity steel structure engages with the snap groove of the first multi-cavity steel structure, so that the two multi-cavity steel structures The connection of the cavity-type steel structure can withstand lateral loads, avoiding weak areas at the connection of the underground diaphragm wall, and improving the waterproof performance of the connection; to the connection of two multi-cavity steel structures and the second multi-cavity Concrete is poured into the cavity of the steel structure, and the construction of the second multi-cavity steel concrete underground diaphragm wall and horizontal joints is completed;

Step 8: Repeat step 7 until the construction of the multi-cavity steel-concrete composite structure with two walls integrated into one is completed.

As a further improvement, in step 5, when the height of the multi-cavity steel structure is lower than the depth of the enclosure structure, vertical joints are welded and fixed on the inner top of the cavity to form a multi-cavity steel structure welded with vertical joints , and then insert the cavity bottom of another multi-cavity steel structure into the vertical joint, and weld the connection. When it is equal to the depth of the enclosure structure, hoist the multi-cavity steel structure group into the preset groove section.

As a further improvement, the hoisting method of the multi-cavity steel structure group is as follows: use a crane to hoist the welded multi-cavity steel structure to the opening of the slot section, and then hoist the upper section of the multi-cavity steel structure and insert it into the vertical joint For positioning welding, lift the connected multi-cavity steel structure group to the bottom of the tank after the weld seam cools down. The specific method of hoisting is: the main and auxiliary cranes are placed at the two ends of the multi-cavity steel structure group along the length direction, and the multi-cavity steel structure group is slowly hoisted horizontally, then the main crane continues to rise, and the auxiliary crane Continue to descend until the multi-cavity steel structure group is turned from the horizontal direction to the vertical direction, adjust the multi-cavity steel structure group to align with the slot opening, and then slowly lower it to complete the multi-cavity steel structure.

As a further improvement, the vertical joint is a square steel pipe (13).

As a further improvement, the axial compression bearing capacity of the section steel unit satisfies the following conditions:

N ₀ ＝f _sc ·(A _sc –(A _s –A _ssn ))+(A _s –A _ssn )·f _y (1)

f _sc ＝(1.212+Bθ+Cθ ² )·f _c (2)

θ＝A _ss1 f _y /A _c f _c (3)

A _ss1 =min{t ₁ ,t ₂ ,t ₃ }·2(b+d) (4)

A _ssn ＝min{t ₁ ,t ₂ ,t ₃ }·2(n·b+d) (5)

B＝0.131f _y /213+0.723 (6)

C=0.026-0.07 f _c /14.4 (7)

In the formula: b is the width of the steel unit; d is the thickness of the steel unit; n is the number of cavities of the steel unit; t ₁ , t ₂ , and t ₃ are the thicknesses of the upper steel plate, web plate and lower steel plate of the steel unit; A _ss1 is the effective confinement steel area of a single cavity, A _ssn is the effective confinement steel area of n cavities; f _y is the yield strength of steel; f _c is the concrete compressive strength; A _c is the concrete cross-sectional area in a single cavity; B , C is the influence coefficient of section shape on the hoop effect; θ is the hoop coefficient of a single cavity; f _sc is the design value of the compressive strength of multi-chamber steel concrete; N ₀ is the axial compressive bearing capacity of multi-chamber steel concrete Design value, A _sc is the total cross-sectional area of the member, and A _s is the cross-sectional area of the steel;

The shear bearing capacity satisfies:

V _u =n·0.71f _sv A _sc -(n-1)·0.58f _y t ₂ (dt ₁ -t ₂ ) (8)

f _sv ＝1.547f _y α _sc /(α _sc +1) (9)

α _sc =A _s /A _c (10)

In the formula: V _u is the shear bearing capacity of multi-cavity steel concrete; f _sv is the design value of the shear capacity of steel concrete in a single cavity; α _sc is the steel content of a single cavity.

The flexural capacity satisfies:

M _u ＝γ _m W _sc f _sc +{max{t ₁ ,t ₃ }-min{t ₁ ,t ₃ }}·b·f _y ·(dt ₁ /2-t ₃ /2), (11)

When t ₂ =min{t ₁ ,t ₂ ,t ₃ };

M _u ＝γ _m W _sc f _sc +(t ₃ -t ₁ )·b·f _y ·(dt ₁ /2-t ₃ /2)+(n+1)·(t ₂ -t ₁ )·f _y ·(dt ₁ -t ₃ ) ² /4 (12)

When t ₁ =min{t ₁ ,t ₂ ,t ₃ };

W _sc =b·d ² /6 (14)

Among them, M _u is the design value of the flexural bearing capacity of the member, W _sc is the section modulus of the flexural member, max{t ₁ ,t ₃ } represents the larger value of t ₁ and t ₃ , min{t ₁ ,t ₃ } represents the smaller value of t ₁ and t ₃ , and γ _m is the plastic development coefficient.

As a further improvement, several stud units (5) are fixed on the inner side of the flange of the steel unit; the horizontal joint includes H-shaped steel (8), and the upper surface and the lower surface of the H-shaped steel (8) are welded and fixed with clip joints. Steel plate (6); the engaging groove is formed by welding a fixed steel plate (61) inside the H-shaped steel unit (2) or directly formed by cold-formed C-shaped steel unit.

As a further improvement, the stud units (5) on the upper part and the stud units (5) on the lower part of the section steel unit are arranged alternately.

As a further improvement, said step 1 includes the following steps:

After clearing the ground and underground obstacles and removing the accumulated water on the ground, the natural elevation of the construction site can meet the requirements of the design elevation through excavation, filling, and leveling;

Described step 2 comprises the following steps:

First use the total station to measure and set out to determine the position of the underground diaphragm wall; after measuring and positioning, excavate the guide groove with an excavator; then manually repair the groove in the local area; Cast-in-place overall reinforced concrete structure; the construction method of the guide wall is as follows: After the trench is excavated to the preset position, the steel bars are bound, and each node is checked step by step to see if it is fixed in place. The support is fixed, and after passing the quality inspection, proceed to the next step of construction to ensure that the guide wall meets the design requirements for clear distance and verticality; finally pour concrete; after the measured strength of the guide wall concrete reaches 85% of the strength design value, the formwork can be removed. Set the upper and lower wooden frame supports behind the formwork, and backfill in time to prevent the excavated guide wall from being deformed by lateral extrusion;

Described step four comprises the following steps:

After determining the position of each section of the groove, use the supporting positioning frame of the milling machine to fix the milling machine on the groove section to ensure the attitude and plane position of the milling bucket entering the groove. The teeth are milled to cut the stratum, and the soil and rock are broken into small pieces. After mixing with the mud in the tank section, the recovered mud is processed by the mud discharge pump and the mud-sand separation system. After the treatment, the clean mud is pumped back into the tank for recycling. , until the final hole is slotted; adopt the construction method of first milling the two ends of the slot section, and then milling the middle. In order to ensure that the verticality will not change greatly due to the cumulative deviation during the milling process, multiple slot measurements are used for different slot sections Deviation correction is used to control the overall verticality of the groove section. In order to ensure the accuracy of ultrasonic groove measurement, the groove section is replaced with mud before each groove measurement to reduce the specific gravity and sand content of the mud in the groove section.

A two-wall-in-one multi-cavity steel-concrete composite structure manufactured by the construction method of the above-mentioned two-wall-in-one multi-cavity steel-concrete composite structure.

Advantages of the present invention:

The present invention replaces traditional steel bars with H (cold-formed C) section steel, which does not need to consider cracking as the outer wall, and the steel has good waterproof performance, which can reduce the enclosure cost caused by water seepage in the later stage, and at the same time, due to the existence of steel as the outer wall during construction , It can avoid the concrete mud phenomenon caused by the hole collapse. The core concrete is constrained by the multi-cavity H-shaped steel or cold-formed C-shaped steel structure, and is in a three-dimensional compression state. The cracking of the concrete is limited, and the compressive bearing capacity, waterproof performance and durability are significantly improved. In addition, the steel structure components in the novel multi-cavity H (cold-formed C) steel-concrete composite structure of the present invention can be prefabricated in the factory, shortening the construction period and simplifying the construction process.

Description of drawings

Figure 1 is a three-dimensional diagram of an H-shaped steel unit;

Figure 2 is a cross-sectional view of the H-shaped steel unit

Fig. 3 is a schematic diagram of a multi-cavity H-shaped steel structure unit;

Fig. 4 is a schematic diagram of a multi-cavity H-shaped steel-concrete composite structure;

Figure 5 is a cross-sectional view of a multi-cavity H-shaped steel-concrete composite structure;

Fig. 6 is the vertical joint form of the H-shaped steel-concrete composite structure;

Fig. 7 is the horizontal joint form of the H-shaped steel-concrete composite structure;

Fig. 8 is a three-dimensional diagram of a cold-formed C-shaped steel unit;

Fig. 9 is a schematic diagram of a multi-cavity cold-formed C-shaped steel structure unit;

Fig. 10 is a three-dimensional diagram of a multi-cavity cold-formed C-shaped steel-concrete composite structure.

Among them, 1. Core concrete unit, 2. H-shaped steel unit, 3. H-shaped steel fillet weld unit, 4. H-shaped steel spliced weld unit, 5. Stud unit, 6. Clamping steel plate, 61. Fixed steel plate, 7 , Steel plate and H (cold-formed C) steel splicing fillet weld unit, 8, H-shaped steel (horizontal joint), 9, multi-cavity H-shaped steel structure unit, 10, cold-formed C-shaped steel unit, 11, C-shaped steel horn-shaped Weld seam unit, 12. Multi-cavity cold-formed C-shaped steel structure unit, 13. Square steel pipe.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Example

The specific manufacturing process of the multi-cavity H (cold-formed C) steel concrete underground continuous wall with two walls in one is as follows:

1. The site is level

After clearing the above-ground and underground obstacles and removing the accumulated water on the ground, the natural elevation of the construction site can meet the design elevation requirements through excavation, filling, and leveling. In the process of leveling the site, establish necessary infrastructure such as water supply, drainage, power supply, roads and temporary buildings that can meet the construction requirements, so that the necessary conditions required in the construction can be fully met.

2. Guide wall construction

First use the total station to measure and set out to determine the position of the underground diaphragm wall. Considering the construction error and the convergence of the support structure during the construction stage, the guide wall should be placed outside properly; after the measurement and positioning, excavate the guide groove with an excavator. The soil on both sides of the guide wall will not be disturbed to prevent the side wall from collapsing; the grooves in some areas will be trimmed manually; After the excavation has a certain strength, start to bind the steel bars, and gradually check whether the fixation of each node is in place. After confirming that it is correct, start to support the formwork, and use lateral supports on the outside of the formwork to fix it. After passing the quality inspection, proceed to the next step of construction to ensure that the guide wall reaches the clear distance The design requirements for verticality and verticality; the final pouring of concrete; the formwork can be removed after the measured strength of the guide wall concrete reaches 85% of the strength design value. The guide wall is deformed by lateral extrusion.

3. Preparation of mud

Set up a mud factory according to the actual needs of the project, and prepare the mud in advance before excavating the trench section. The mud can generate certain hydrostatic pressure on the tank wall, resist the lateral earth pressure and water pressure acting on the tank wall, and prevent the tank wall from collapsing and falling off; in addition, the mud can also act as a lubricant to reduce the Reduce the loss of digging machines and improve the efficiency of trench section excavation.

4. Groove construction

After determining the position of each section, use the supporting positioning frame of the slot milling machine to fix the slot milling machine on the slot section to ensure the attitude and plane position of the milling bucket entering the slot. The slot milling machine cuts the strata through the milling teeth of different shapes and hardnesses installed on the milling wheel, breaks the soil and rocks into small pieces, mixes them with the mud in the slot section, and then processes and recycles them through the mud discharge pump and mud-sand separation system Slurry, the clean mud after treatment is pumped back into the tank for recycling until the final hole is formed into a slot. The construction method of milling both ends of the groove section first, and then milling the middle is adopted. In order to ensure that the verticality will not change greatly due to the cumulative deviation during the milling process, for different slot sections, multiple slot measurement corrections are used to control the overall verticality of the slot section. In order to ensure the accuracy of ultrasonic slot measurement, each slot measurement Mud replacement is performed on the tank section beforehand to reduce the specific gravity and sand content of the mud in the tank section.

5. Hoisting multi-cavity H (cold-formed C) steel structure

If the enclosure structure is deep and the length of the multi-cavity H (cold-formed C) steel structure cannot meet the requirements, vertical joints are required to vertically splice the multi-cavity H (cold-formed C) steel structure. The square steel pipe is used as the vertical joint spot welding and fixed on the multi-cavity H (cold-formed C) steel structure below, and the welded multi-cavity H (cold-formed C) steel structure is hoisted to the opening of the slot section by a crane , and then hang the upper section of multi-cavity H (cold-formed C) steel structure and insert it into the vertical joint for positioning welding with the lower section of multi-cavity H (cold-formed C) steel structure. After the weld is cooled, the connected The multi-cavity H (cold-formed C) steel structure is hoisted to the bottom of the tank. The specific method of hoisting is: the main and auxiliary cranes are placed on the two ends of the multi-cavity H (cold-formed C) steel structure along the length direction, and the multi-cavity H (cold-formed C) steel structure is slowly hoisted horizontally at the same time. Then the main crane continues to rise, and the auxiliary crane continues to descend until the multi-cavity H (cold-formed C) steel is turned from the horizontal direction to the vertical direction, and the multi-cavity steel structure is adjusted slowly after aligning with the slot mouth. Lowering to complete the hoisting of multi-cavity steel.

6. Pour underwater concrete

Concrete is poured into the underground diaphragm wall using the conduit method. The number of pipe joints required is determined according to the excavation depth of the groove section. The number of cavities inside determines the number of required conduits. Each cavity needs to be lowered with a conduit, and the gap between the multi-chamber H (cold-formed C) steel structural steel plate and the tank wall also needs to be placed with a conduit. Pour concrete. When the concrete starts pouring, first place a water-proof ball in the pipe so that the mud in the pipe can be discharged from the bottom of the pipe when the concrete is poured. During the concrete pouring process, the concrete should be continuously and uniformly fed, and the concrete surface elevation and the buried depth of the conduit should be observed and measured at any time during the pouring process, and the conduit mouth should not be lifted out of the concrete surface.

7. Construction of the second multi-cavity H (cold-formed C) steel concrete underground diaphragm wall

Excavate the second unit groove section according to step 4; weld the horizontal joint and the steel plate at the head end of the multi-cavity H (cold-formed C) steel structure, and the horizontal joint consists of H-shaped steel, H-shaped steel fillet welds, steel plates, and the splicing of steel plates and H-shaped steel The fillet weld consists of four parts. Weld the flange of the horizontal joint (H-shaped steel) with the steel plate at the head end of the multi-cavity H (cold-formed C) steel structure; follow step 5 to weld the welded multi-cavity H (cold-formed C) C) The shaped steel structure is hoisted to the second trough section, so that the steel plate of the horizontal joint can occlude with the steel plate at the end of the first multi-cavity H (cold-formed C) underground diaphragm wall. There are weak areas at the junction of the continuous wall, in addition to improving the waterproof performance of the junction; concrete is poured into the horizontal junction and the multi-chamber H (cold-formed C) steel structure cavity to complete the second multi-chamber type Construction of H (cold-formed C) steel-concrete underground diaphragm walls and horizontal joints.

Use the acoustic wave transmission method to test the quality of the wall concrete. The number of tested wall sections should not be less than 20% of the total number of wall sections under the same conditions, and should not be less than 3 pieces. The number of pre-embedded ultrasonic tubes for each tested wall section should not be less At least 4, and should be arranged at the midpoint of the four sides of the wall section; when the quality of the wall determined by the sound wave transmission method is unqualified, the core drilling method should be used for verification.

When designing a multi-cavity steel structure, its compressive bearing capacity meets:

N ₀ ＝f _sc ·(A _sc –(A _s –A _ssn ))+(A _s –A _ssn )·f _y (1)

f _sc ＝(1.212+Bθ+Cθ ² )·f _c (2)

θ＝A _ss1 f _y /A _c f _c (3)

A _ss1 =min{t ₁ ,t ₂ ,t ₃ }·2(b+d) (4)

A _ssn ＝min{t ₁ ,t ₂ ,t ₃ }·2(n·b+d) (5)

In the formula: b is the width of the member; d is the thickness of the member; n is the number of cavities; t ₁ , t ₂ , and t ₃ are the thicknesses of the upper steel plate, web plate, and lower steel plate of the multi-cavity H-shaped steel concrete. C-shaped steel concrete t ₁ , t ₂ , and t ₃ are the same; A _ss1 is the effective confinement steel area of a single cavity, and A _ss1 is the effective confinement steel area of n cavities; f _y is the yield strength of steel; f _c is the concrete compressive strength _Strength ; A _c concrete area; the definition and value method of B and D are the same as the concrete filled steel pipe specification; _θ is the hoop coefficient of a single cavity; The design value of concrete strength consists of two parts, one part is the area of effectively constrained steel and the bearing capacity of concrete components, and the other is non-effectively constrained steel (the thickness of any steel is t, the thickness of non-effectively constrained steel is t-min{t ₁ , t ₂ , t ₃ }), the formula considers that the restraint of steel on concrete depends on the thinnest steel plate around the concrete in the cavity, and the thickest steel plate only takes the same thickness as the thinnest steel plate as the effective restraint of concrete. The first item of the equation, and the steel not included in the first item bears the axial force as the second item.

The shear bearing capacity satisfies:

V _u ＝n·0.71f _sv A _sc -(n-1)·0.58f _y t ₂ (dt ₁ -t ₂ ) (6)

f _sv ＝1.547f _y α _sc /(α _sc +1) (7)

α _sc =A _s /A _c (8)

In the formula: V _u is the shear bearing capacity of multi-cavity steel concrete, and the bearing capacity of n cavities is the superposition of the shear bearing capacity of n rectangular steel tube concrete, minus the shared (n-1) web Shear bearing capacity; f _sv is the design value of the shear bearing capacity of single cavity steel concrete (single cavity steel concrete, namely rectangular steel tube concrete), and the remaining symbols are the same as those in the axial compression bearing capacity formula.

The flexural capacity satisfies:

M _u ＝γ _m W _sc f _sc +{max{t ₁ ,t ₃ }-min{t ₁ ,t ₃ }}·b·f _y ·(dt ₁ /2-t ₃ /2), (9)

When t ₂ =min{t ₁ ,t ₂ ,t ₃ };

M _u ＝γ _m W _sc f _sc +(t ₃ -t ₁ )·b·f _y ·(dt ₁ /2-t ₃ /2)+(n+1)·(t ₂ -t ₁ )·f _y ·(dt ₁ -t ₃ ) ² /4 (10)

When t ₁ =min{t ₁ ,t ₂ ,t ₃ };

W _sc =b·d ² /6 (12)

In the formula: in order to make full use of the concrete in the compression zone, t ₃ will not be the smallest under normal circumstances; γ _m is the plastic development coefficient; W _sc is the section modulus of the flexural member; Therefore, it is determined by the web thickness of a single cavity, and the second item is the flexural bearing capacity of the non-effectively constrained steel; the first item in formula (10) is determined by the thickness of the steel flange plate in the compression zone, and the second The first term is to consider the flexural capacity of the non-effectively restrained steel in the tension zone, and the third term is to consider the flexural capacity of the non-effectively restrained steel in the web to achieve full-section plasticity.

Although the embodiment of the present invention has been disclosed as above, it is not limited to the use listed in the specification and embodiment, it can be applied to various fields suitable for the present invention, and it can be easily understood by those skilled in the art Further modifications can be effected, so the invention is not limited to the specific details and examples shown and described herein without departing from the general concept defined by the claims and their equivalents.

Claims (8)

1. A construction method of a multi-cavity steel-concrete composite structure with two walls in one, is characterized in that, comprises the steps: Step 1. The site is leveled; Step two, guide wall construction; Step 3, preparing mud; Step 4, groove construction; Step five, hoisting multi-cavity steel structure: The multi-chamber shaped steel structure includes several shaped steel units, the shaped steel units are H-shaped steel units (2) or cold-formed C-shaped steel units; the flanges of the shaped steel units are welded and spliced to each other in sequence to form a multi-cavity shaped steel structure with openings at both ends; One end of the multi-cavity steel structure is formed with a horizontal joint, and the other end forms an engaging groove for matching with the horizontal joint; the middle part of the multi-cavity steel structure forms several cavities of the same size; The axial compression bearing capacity of the section steel unit satisfies the following conditions: N ₀ =f _sc ·(A _sc -(A _s -A _ssn ))+(A _s -A _ssn )·f _y (1) f _sc ＝(1.212+Bθ+Cθ ² )·f _c (2) θ＝A _ss1 f _y /A _c f _c (3) A _ss1 = min{t ₁ , t ₂ , t ₃ }·2(b+d) (4) A _ssn = min{t ₁ , t ₂ , t ₃ }·2(n·b+d) (5) B＝0.131f _y /213+0.723 (6) C=0.026-0.07 f _c /14.4 (7) In the formula: b is the width of the multi-cavity steel structure; d is the thickness of the multi-cavity steel structure; n is the number of cavities of the multi-cavity steel structure; t ₁ , t ₂ , t ₃ are the upper Thickness of steel plate, web plate, and lower steel plate; A _ss1 is the effective confinement steel area of a single cavity, A _ssn is the effective confinement steel area of n cavities; f _y is the yield strength of steel; f _c is the compressive strength of concrete; A _c is The cross-sectional area of concrete in a single cavity; B and C are the influence coefficients of the section shape on the hoop effect; θ is the hoop coefficient of a single cavity; f _sc is _the design value of the compressive strength of multi-cavity steel concrete; The design value of the axial compressive bearing capacity of steel concrete, A _sc is the total cross-sectional area of the member, and A _s is the cross-sectional area of the steel; The shear bearing capacity satisfies: V _u =n·0.71f _sv A _sc -(n-1)·0.58f _y t ₂ (dt ₁ -t ₂ ) (8) f _sv ＝1.547f _y α _sc /(α _sc +1) (9) α _sc =A _s /A _c (10) In the formula: Y _u is the design value of the shear bearing capacity of the multi-cavity steel concrete member; f _{sv is} the design value of the shear strength of the single cavity steel concrete; α _sc is the steel content of a single cavity; The flexural capacity satisfies:

W _sc =b·d ² /6 (14) Among them, _Mu is the design value of the flexural bearing capacity of the member, W _sc is the section modulus of the flexural member, max{t ₁ , t ₃ } represents the larger value of t ₁ and t ₃ , min{t ₁ , t ₃ } represents the smaller value among t ₁ and t ₃ , and γ _m is the plastic development coefficient; Step six, pouring underwater concrete: Concrete is poured using the conduit method, and the number of pipe joints required is determined according to the excavation depth of the groove section. The number of bodies determines the number of pipes required. Each chamber needs to be lowered with a pipe, and the gap between the steel plate and the tank wall of the multi-chamber steel structure is also placed in a pipe to pour concrete; when the concrete starts pouring, first Place a water-proof ball in the conduit so that the mud in the pipe can be discharged from the bottom of the conduit when the concrete is poured; Step 7. Construction of the second multi-cavity steel concrete underground diaphragm wall: Excavate the second unit groove section; hoist the second multi-cavity steel structure so that the horizontal joint of the second multi-cavity steel structure engages with the snap groove of the first multi-cavity steel structure, so that the two multi-cavity steel structures The connection of the cavity-type steel structure bears lateral loads, avoids weak areas at the connection of the underground diaphragm wall, and improves the waterproof performance of the connection; to the connection of two multi-cavity steel structures and the second multi-cavity steel Concrete is poured into the cavity of the structure, and the construction of the second multi-cavity steel concrete underground diaphragm wall and horizontal joints is completed; Step 8: Repeat step 7 until the construction of the multi-cavity steel-concrete composite structure with two walls integrated into one is completed. 2. The construction method of the multi-cavity type steel-concrete composite structure with two walls in one as claimed in claim 1, wherein, in the step 5, when the height of the multi-cavity type steel structure is lower than the depth of the enclosure structure, Vertical joints are welded and fixed on the top of the inner side of the cavity to form a multi-cavity steel structure welded with vertical joints, and then the cavity bottom of another multi-cavity steel structure is inserted into the vertical joints and connected by welding. Several multi-cavity steel structures are connected to form a multi-cavity steel structure group. When the multi-cavity steel structure group is greater than or equal to the depth of the enclosure structure, the multi-cavity steel structure group is hoisted into the preset groove section. 3. The construction method of the multi-cavity type steel-concrete composite structure with two walls in one as claimed in claim 2, characterized in that, the hoisting method of the multi-cavity type steel structure group is as follows: use a crane to weld the multi-cavity Hoist the cavity-type steel structure to the mouth of the groove section, and then hoist the upper section of the multi-cavity type steel structure and insert it into the vertical joint for positioning welding. After the weld is cooled, hoist the connected multi-cavity type steel structure group to the bottom of the groove; The specific method of hoisting is: the main and auxiliary cranes are placed at the two ends of the multi-cavity steel structure group along the length direction, and the multi-cavity steel structure group is slowly hoisted horizontally, then the main crane continues to rise, and the auxiliary crane Continue to descend until the multi-cavity steel structure group is turned from the horizontal direction to the vertical direction, adjust the multi-cavity steel structure group to align with the slot opening, and then slowly lower it to complete the multi-cavity steel structure. 4. The construction method of the multi-cavity steel-concrete composite structure with two walls in one as claimed in claim 2, characterized in that, the vertical joint is a square steel pipe (13). 5. the construction method of the multi-cavity type steel-concrete composite structure with two walls in one as claimed in claim 1, is characterized in that, the flange inboard of described steel unit is fixed with some stud units (5); The joint includes H-shaped steel (8), and the upper surface and the lower surface of the H-shaped steel (8) are welded and fixed with clamping steel plates (6); ) or formed directly from cold-formed C-shaped steel units. 6. The construction method of the multi-cavity steel-concrete composite structure with two walls in one as claimed in claim 5, characterized in that, the stud unit (5) at the top of the steel unit and the stud unit (5) at the bottom interlaced with each other. 7. The construction method of the multi-cavity steel-concrete composite structure with two walls in one as claimed in claim 1, wherein said step one comprises the following steps: After clearing the ground and underground obstacles and removing the accumulated water on the ground, the natural elevation of the construction site can meet the requirements of the design elevation through excavation, filling, and leveling; Described step 2 comprises the following steps: First use the total station to measure and set out to determine the position of the underground diaphragm wall; after measuring and positioning, excavate the guide groove with an excavator; then manually repair the groove in the local area; The cast-in-place overall reinforced concrete structure; the construction method of the guide wall is as follows: after the trench is excavated to the preset position, start to tie the steel bars, check whether each node is fixed in place step by step, start to support the formwork after confirming that it is correct, and use lateral supports on the outside of the support formwork Fix it, pass the quality inspection and then enter the next step of construction to ensure that the guide wall meets the design requirements for clear distance and verticality; finally pour concrete; after the measured strength of the guide wall concrete reaches 85% of the strength design value, the formwork can be removed. Finally, set the upper and lower wooden beam supports, and backfill in time to prevent the excavated guide wall from being deformed by lateral extrusion; Described step four comprises the following steps: After determining the position of each section of the groove, use the supporting positioning frame of the milling machine to fix the milling machine on the groove section to ensure the attitude and plane position of the milling bucket entering the groove. The teeth are milled to cut the stratum, and the soil and rock are broken into small pieces. After mixing with the mud in the tank section, the recovered mud is processed by the mud discharge pump and the mud-sand separation system. After the treatment, the clean mud is pumped back into the tank for recycling. , until the final hole is slotted; adopt the construction method of first milling the two ends of the slot section, and then milling the middle. In order to ensure that the verticality will not change greatly due to the cumulative deviation during the milling process, multiple slot measurements are used for different slot sections Deviation correction is used to control the overall verticality of the groove section. In order to ensure the accuracy of ultrasonic groove measurement, the groove section is replaced with mud before each groove measurement to reduce the specific gravity and sand content of the mud in the groove section. 8. A two-wall-in-one multi-cavity steel-concrete composite structure manufactured by the construction method of any one of claims 1-7.

Images