CN1333139C - Column supported underground continuous wall - Google Patents

Abstract

The present invention relates to a column supported underground continuous wall which adopts a basement inverse method to construct and comprises underground wall bodies arranged along the periphery of a basement. The present invention is characterized in that each underground wall body is composed of a shallow wall body and deep wall body, wherein each shallow wall body is positioned at the upper part of the underground continuous wall, has wall body structure of the common underground continuous wall, forms a closed type wall body along the periphery of the basement, and is used for blocking soil, blocking water, and preventing leakage when the basement inverse method is constructed. Each deep wall body is positioned below the shallow wall body, and a column supported wall body at a column supported rock inserted section is arranged by an intermittent method; each deep wall body is used for supporting a shallow wall body section, and serves as a vertical supporting structural member of a floor of the basement so as to effectively control the vertical deformation of upper structure of the underground continuous wall. Because the shallow wall bodies reduce the height of the underground continuous wall and the column supported wall bodies of the deep wall bodies reduce the numbers of intrude rock wall sections of the underground continuous wall with high cost and large difficulty, thereby, the present invention can greatly shorten construction time and can reduce cost.

Description

A pillar-supported underground continuous wall

technical field

The invention relates to an underground continuous wall of a building, in particular to a pillar-supported underground continuous wall constructed by a basement upside-down method.

Background technique

The underground diaphragm wall of a building is a kind of foundation pit support system of a water-retaining and soil-retaining structure applied to the construction of the basement structure in the reverse method. One of the most commonly used support techniques.

In the prior art, the multi-storey basements of high-rise buildings and other multi-storey underground structures are often constructed using the reverse construction method, that is, the floor structure of the basement, including beams, plates, columns, etc., and external wall structures are used as the level of the foundation pit enclosure structure. For the support system and the enclosure system, the base layer is used as the boundary in the reverse method, and the basement of each layer below the base layer is constructed from top to bottom, and the layers above the base layer can be constructed from bottom to top at the same time, so it is called the reverse method. Since the basement upside-down method needs to ensure that the basement built from top to bottom has sufficient horizontal rigidity and the deformation of the foundation pit is small, it is necessary to use a diaphragm wall as the foundation pit support for retaining soil in poor soil layers from the ground down during construction. protection system.

The underground diaphragm wall needs to use special equipment to excavate a trench with a certain width, thickness and depth along the deep foundation or the surrounding of the underground structure with a mud retaining wall. It is determined according to the design requirements of the building and the geological conditions. A reinforcement cage is set in the groove, concrete is poured in the mud by the conduit method, and a unit wall section several meters wide is built, and the construction is performed sequentially, and a continuous underground reinforced concrete wall is formed by connecting the unit wall sections by a certain joint method, In order to prevent seepage and retain soil during the excavation of the foundation pit, as a support for the foundation of adjacent buildings and directly become a part of the foundation structure bearing direct loads, the underground diaphragm wall is usually constructed into the rock layer more than 2 meters deeper than the basement floor. Its disadvantages are:

(1) Since the construction of the underground diaphragm wall requires large-scale special machinery, the groove section is generally formed by drilling and punching, and the wall is protected by mud, so the construction cost is relatively high.

(2) It is difficult for the diaphragm wall to excavate into grooves in hard soil and rock layers, especially when the rock layers are buried shallowly, that is, when the geological conditions are good, and in the case of a multi-layer basement, the increased cost of entering the rock is very large. The project cost increased greatly.

(3) Due to the close connection between the underground diaphragm wall and the reverse method technology, the high cost of the diaphragm wall directly affects the application and promotion of the basement reverse method technology. How to ensure the safety of the foundation pit project can shorten the construction period and at the same time control the project cost , has become a key issue affecting the development of reverse technology.

Contents of the invention

The object of the present invention is to provide a pillar-supported underground continuous wall which can shorten the construction period and control the construction cost under the condition of ensuring the safety of the foundation pit project.

The present invention is a pillar-supported underground continuous wall constructed by the upside-down method of the basement, which includes an underground wall arranged along the periphery of the basement. The wall is located on the upper part of the underground diaphragm wall, and has a common underground diaphragm wall structure, forming a closed wall along the periphery of the basement, which is used for retaining soil, retaining water, and impermeability during the reverse construction of the basement; the deep wall is located at Under the shallow wall, the column-supported rock-socketed section of the column-supported wall is set intermittently, which is used to support the shallow wall section and as a vertical supporting structural member of the basement floor, which can effectively control the vertical deformation of the upper structure of the underground continuous wall . Because the shallow wall reduces the height of the underground diaphragm wall, the deep wall pillar wall reduces the number of expensive and difficult underground diaphragm walls entering the rock wall, thereby greatly shortening the construction period and reducing costs (see Figure 2, 3).

In the present invention, the underground diaphragm wall is divided into shallow wall and deep wall. The shallow wall at the position of unfavorable soil still adopts the existing underground diaphragm wall structure, while the deep wall at the position with good geological conditions is no longer The continuous wall structure in the prior art is adopted, but the discontinuous wall structure is adopted. This technical solution is realized on the basis of two major characteristics of the basement upside-down method. The two major features mentioned are: (1) the existence of the soil arch effect; (2) the internal support of the underground diaphragm wall is guaranteed in the reverse method, that is, the overall structure formed by the underground diaphragm wall, floor beams, slabs and columns, utilizes Its lateral stiffness has a strong fixed horizontal support effect on the lateral earth pressure of the foundation pit. The feasibility of the present invention is verified by systematically and exhaustively carrying out a large amount of finite element numerical simulation analysis, monitoring data verification and actual engineering application practice on the technology and concept of the present invention.

In the reverse construction of the basement, the first construction is the underground continuous wall around the basement, and at the same time, pour or lay down the intermediate support piles and columns at the relevant positions inside the building (the intersection of columns or partition walls, etc., calculated according to needs) During the construction period, before the base plate is sealed, it bears the self-weight of the upper structure and the support of the applied load. After the underground diaphragm wall and piles are completed, the excavation of the foundation pit and the construction of floor beams and slabs are carried out layer by layer from top to bottom. The beam-slab floor structure of the reference floor is constructed first to form the first horizontal support on the upper part of the surrounding underground diaphragm wall. The huge horizontal rigidity of the floor structure becomes a great support for the underground diaphragm wall. Excavate the earthwork layer by layer and pour the underground structure of each layer until the bottom plate is sealed. In this construction process, no matter whether temporary horizontal support is added to the underground diaphragm wall to balance the earth pressure acting on the underground diaphragm wall, every time a floor beam slab is completed, an additional horizontal support will be formed on the underground diaphragm wall , so that the internal support of the underground diaphragm wall is guaranteed, that is, the underground diaphragm wall, floor beams, slabs and piles form an overall space structure with huge rigidity, which can play a role in the lateral earth pressure acting on the underground diaphragm wall. Strong fixed horizontal support effect.

Although the geological conditions of each building construction are different, the geological conditions of general building construction include two parts of soil. One part of the soil is unfavorable soil located on the upper part of the ground, with strong water permeability and loose soil. , the internal friction angle α representing the stability of the soil (see Figure 1) is small, and when the foundation pit is excavated in an open manner, it is easy to cause soil landslides, and the angle of the landslide coincides with the internal friction angle α of the soil . Miscellaneous fill soil layers, silt layers, sand layers, plastic silty clay layers, etc. all belong to unfavorable soil bodies. The other part of the soil is good soil located under the bad soil. The soil (rock) is dense, high in strength and hardness, poor in water permeability or even impervious to water, and the internal friction angle α is relatively large. rock formations. The depth of unfavorable soil in different regions will be different. According to the geological differences between the north and the south of my country, the depth difference of unfavorable soil in the south and north can reach as much as 20 to 30 meters, and the depth of unfavorable soil in the south is smaller , the depth of unfavorable soil in the north is greater.

In the reverse construction of the basement, the unfavorable soil located on the upper part of the foundation pit has a huge rigidity due to the overall structure of the basement formed by the underground continuous wall, floor beams, piles, etc., which is sufficient to prevent the slippage of the soil layer . Therefore, the sliding damage of the side wall of the foundation pit in the unfavorable soil position is almost non-existent. And when the better soil (rock) layer continues to excavate downward, the unexcavated lower soil is used as the supporting point of the exposed foundation pit soil, and the upper basement of the rigid body is used as the upper supporting point of the foundation pit. , after being supported up and down, a soil arch effect will be formed in the soil body of the excavation surface (see Figure 4), so that the resultant force of earth pressure acting on the enclosure structure at this position is small, which can prevent the unsupported soil body from slipping and uplifting role. Using this technology within a suitable height range can reasonably use the physical properties of the better soil layer itself to achieve its own stabilization effect, and the requirements for retaining soil on this part can be greatly reduced. If the entry is unweathered or slightly weathered The rock strata may not even need to consider the soil retaining requirements, and after entering the impermeable soil (rock) layer, there is no need for water stop requirements. The underground diaphragm wall at this position actually only plays a load-bearing role, so there is no need for all The wall sections are all embedded in the hard soil layer, and only need to set the pillars at a certain distance to support the wall, so that the load-bearing and vertical support components can be realized, so that most of the conventional retaining wall components can be omitted in this position. possible.

The height of the shallow wall in the present invention is based on the depth of the unfavorable soil in actual geology, and its height should be sufficient to cover all unfavorable soil layers, so as to ensure that the shallow wall section can fully play the role of retaining water and soil.

The shallow wall section of the present invention is preferably able to extend below the basement floor elevation at the maximum depth of the unfavorable soil body, so as to ensure the stability of the support system.

The height of the deep wall section according to the present invention is from below the shallow wall section to the rock formation below the foundation pit floor, and the boundary between the shallow wall section and the deep wall section should be set within the range of 300-1500mm below the elevation of the basement floor, preferably The range is 400-1000mm.

The present invention can make the following improvements: in the deep wall part, the distance between every two adjacent pillar walls is in the range of 10-30 meters; the preferred range is 15-20 meters.

The present invention can be improved as follows: due to the discontinuous column-supported wall of the deep wall of the present invention, the wall section between the two column-supported walls of the shallow wall becomes a suspended wall section, and the shallow wall The entire underground diaphragm wall is formed by dividing the entire underground diaphragm wall into multiple unit widths, and the walls of each unit are generally joined longitudinally by I-shaped steel or similar components. Therefore, in order to strengthen the transverse strength of the underground diaphragm wall, all The underground diaphragm wall and the basement wall are combined into a whole. The basement wall is referred to as the inner wall for short. The transverse reinforcement structure of the inner wall constructed layer by layer is used to improve the transverse strength of the suspended wall section of the underground diaphragm wall. The specific technical measure is to pre-embed a plurality of steel bars used to connect the inner wall on the inner surface of the underground diaphragm wall, the inner wall is formed close to the underground diaphragm wall, and a part of the pre-embedded steel bars of the underground diaphragm wall extends into the inner wall , is fixed in it when the inner wall is poured, so that the two walls are combined into a whole.

The present invention can further install the first-floor ring beam on the top of the shallow wall section of the underground continuous wall, and the top of the shallow wall is provided with longitudinal steel bars, which are connected with the first-floor ring beam, and the transverse strength of the ring beam is used to improve the shallow wall. The other ring beams of each layer are embedded in the inner wall of the underground diaphragm wall and poured together to form a complete and firm one, so that the combined shallow wall suspended wall section and the inner wall become a continuous deep beam, further strengthening the underground The structural strength of the suspended wall section of the shallow wall body of the diaphragm wall.

In the underground continuous wall according to the present invention, PVC pipes are pre-embedded at all joints with the floor frame beams so that the subsequent process can be cut open to connect with the frame beams. Rigid connection with the underground diaphragm wall, instead of the old method of using steel beam box embedded parts, can save a lot of steel and simplify the process.

The present invention can also be further improved: a spray-anchor support composite member is arranged between the two adjacent pillar walls of the deep wall, that is, when the geological conditions are good, the upper support and the excavation surface soil A favorable soil arch effect can be formed between the holes, and the side wall of the foundation pit between every two pillar wall sections embedded in the rock layer below the bottom plate is sprayed and anchored, including fixing the metal mesh on the side of the foundation pit with anchor rods or soil nails The wall and sprayed concrete form a thin wall structure with a certain soil retaining effect. It can be applied to the side walls of deep basement pits with a depth of more than 10 meters, and can save a lot of investment in the reverse construction of ultra-deep foundation pits.

Compared with the prior art, the present invention has the following advantages:

1. The present invention adopts a column-supported underground diaphragm wall including shallow wall and deep wall structure as foundation pit enclosure components, and the shallow wall applies conventional underground diaphragm wall technology, combined with the column-supported underground diaphragm wall arranged at intervals of the deep wall. The wall, using the good soil arch effect and the similar rigid horizontal support on the upper part of the underground diaphragm wall, not only ensures the stability of the lower soil itself, but also effectively reduces the depth of the diaphragm wall and reduces the high cost, The quantity of the difficult underground diaphragm wall entering the rock wall is reduced by 20% to 40%, thereby reducing the amount of materials and enclosure measures, shortening the construction period, and greatly reducing the project cost.

2. The present invention can combine the underground diaphragm wall and the basement wall into a whole, which not only strengthens the lateral strength of the suspended wall section of the shallow wall of the underground diaphragm wall, but also saves the separately established enclosure wall, and can maximize the space within the scope of land use. Greatly expand the effective use area of the basement;

3. In the present invention, the ring beams on the first floor or each floor and the inner wall at the suspended wall section of the shallow wall are poured together and integrated firmly. In design, the column-supported wall section can be regarded as the support of the suspended wall. The suspended wall section and the inner wall are combined to form a continuous deep beam, which is then supported by vertical beams and anchors to form a stable space frame system, which solves the problem of simply using the underground continuous wall as foundation pit support. high problem

4. The present invention combines the underground diaphragm wall with the sprayed-anchor support composite component to realize the soil retaining effect at the discontinuous space of the deep wall at a lower cost, and can be applied to the side wall of the deep basement pit more than 10 meters deep. It saves a lot of investment in the reverse construction of ultra-deep foundation pit.

5. The present invention is mainly used in the design and construction of basements with more than three floors. It has been successfully applied to deep foundation pit projects of many high-rise (super high-rise) buildings, and has obtained remarkable economic benefits. The reverse method design and construction of deep foundation pits The development of technology and the improvement of the research on the mechanism of deep foundation pit soil and structure have great academic significance, and have broad application prospects in engineering practice.

Description of drawings

Fig. 1 is the earth pressure schematic diagram of the underground diaphragm wall with horizontal support;

Fig. 2 is the top view structure schematic diagram of the underground continuous wall of embodiment 1 of the present invention;

Fig. 3 is a 1/4 partial three-dimensional structural schematic diagram of the basement overall structure in which the underground diaphragm wall shown in Fig. 2 is combined with the floor covering, beams and columns;

Fig. 4 is a 1/4 partial three-dimensional structural schematic diagram of the combination of the underground diaphragm wall and the beam shown in Fig. 2;

Fig. 5 is the schematic front view of the basement structure showing the arching action of the lower layer of soil in Embodiment 1 of the present invention;

Fig. 6 is a schematic front view of the basement structure of Embodiment 2 of the present invention;

Fig. 7 removes the three-dimensional structural diagram of the negative second floor floor and the inner wall for the underground diaphragm wall shown in Fig. 6;

Fig. 8 is a top view structural diagram of the connection between the underground diaphragm wall and the inner wall according to Embodiment 2 of the present invention;

Fig. 9 is a schematic diagram of the front view of the connection between the underground diaphragm wall and the inner wall according to Embodiment 2 of the present invention;

Fig. 10 is a schematic diagram of the connection between the underground continuous wall and the ring beam and the floor beam slab according to Embodiment 2 of the present invention.

Detailed ways

Example 1

As shown in Figures 2 to 5, a pillar-supported underground continuous wall constructed by the reverse construction method of the basement is one of the embodiments of the present invention, which includes an underground wall arranged along the periphery of the basement, and is characterized in that the underground wall consists of shallow The wall body 11 and the deep wall body 12 are composed, and the shallow wall body 11 is located at the upper part of the underground diaphragm wall 1, has a common underground diaphragm wall body structure, forms a closed wall body along the periphery of the basement, and covers all unfavorable soil bodies A, It is used for soil retaining, water retaining and anti-seepage in basement reverse construction. The superstructure of the basement composed of the shallow wall, the floor 4, the beam 5 and the column 3 has a huge lateral rigidity, and the displacement of the lateral earth pressure is small, so it can be regarded as a fixed horizontal support of the soil.

The deep wall 12 extends from the lower part of the shallow wall to the rock-socketed, using the completed superstructure of the basement as the upper support, and the hard soil (rock) at the bottom of the pit as the lower support, under the action of lateral earth pressure , to form the soil arch effect C to ensure its own stability, so that the water retaining and soil retaining structures of this part can be omitted, and the pillar walls of the pillar-supported rock-socketed section are set in an intermittent manner, and every two adjacent pillar walls The distance between the bodies is 18 meters, which is used for the support of the soil layer part B of the foundation pit with good geological conditions, supporting the shallow wall body 11 and serving as the vertical supporting structural member of the basement floor, effectively controlling the upper structure of the underground diaphragm wall. Vertical deformation.

Example 2

The column-supported underground diaphragm wall shown in Figures 6 to 10 is the second embodiment of the present invention. The difference from the previous example is that between two column-supported walls adjacent to the deep wall body 12 of the underground diaphragm wall The spacing is 20 meters, and the sprayed anchor support composite member 2 is set in this spacing, that is, the sprayed anchor support is used between adjacent column walls, that is, the metal mesh is fixed on the side wall of the foundation pit with soil nails 21 Then spray concrete to form a thin wall structure with a certain soil retaining effect. In addition, an anchor rod 22 is driven into the lower part of the shallow wall to further strengthen the horizontal support of the shallow wall.

As shown in Figures 6, 8, and 9, the shallow wall of the underground diaphragm wall is formed by dividing the entire underground diaphragm wall into multiple unit widths and constructing them one by one. The walls of each unit are generally joined by I-shaped steel 13. Steel trusses 14 and transverse and vertical ribs 15 and 16 are all arranged in each unit wall. The underground diaphragm wall 1 and the inner wall 6 are combined into a whole, and the inner wall 6 is formed close to the underground diaphragm wall, and its height is from the top of the shallow wall 11 to the bottom of the deep wall 12, and the inner wall is set in the same way There are horizontal and vertical ribs 61 and 62, but the difference is that the horizontal ribs 61 are continuous throughout the wall. The thickness of the inner wall 6 is small at the shallow wall 11, and when it reaches the deep wall 12, the shallow wall between the two pillar walls is suspended below the wall, and the inner wall 6 is also close to the spray anchor support The layer is formed to fill the space under the suspended wall of the shallow wall.

As shown in Figure 9, on the inner surface of the underground diaphragm wall 1, many connecting steel bars 7 for connecting the inner wall 6 are pre-buried. Into the shallow wall 11, the two ends of the pre-embedded section are cross-folded towards the inner surface of the shallow wall, and the folded ends 72 are pulled out to extend into the inner wall area in the form of an "X" during the construction of the inner wall. The inner wall is fixed in it when pouring and forming, and the inner wall is formed close to the underground continuous wall, and the two walls are combined into a whole under the action of the connecting steel bar 7 . The inner wall is equipped with complete vertical reinforcement and transverse reinforcement, which can improve the lateral strength of the suspended wall section of the shallow wall.

As shown in Figures 6, 7, and 10, the ring beam 51a on the first floor of the basement is installed on the top of the shallow wall section of the underground diaphragm wall. The top of the shallow wall is provided with longitudinal reinforcement, which is connected with the ring beam on the first floor. strength to improve the lateral strength of the shallow wall; the remaining ring beams 51b of each layer are embedded in the inner wall of the suspended wall section of the underground diaphragm wall and poured into a complete and firm one, so that the combined shallow wall suspended wall section And the inner wall becomes a continuous deep beam.

The underground diaphragm wall is pre-embedded with PVC pipes and reinforced steel bars at all joints with the floor frame beams, so that connection gaps are cut out, and the frame beam steel bars 52 are stretched in, which can make the floor frame beams and the underground diaphragm wall rigid. Connection, instead of the old method of using steel beam box embedded parts, can save a lot of steel and simplify the process.

Claims (10)

1. A pillar-supported underground continuous wall, comprising an underground wall arranged along the basement periphery, characterized in that said underground wall is made up of a shallow wall (11) and a deep wall (12), and said shallow wall The body (11) is located on the upper part of the underground diaphragm wall (1), has a common underground diaphragm wall structure, forms a closed wall along the periphery of the basement, and is used for retaining soil, retaining water, and preventing seepage during the reverse construction of the basement; The deep wall (12) is located below the shallow wall, and the column-supported wall of the column-supported rock-socket section is arranged intermittently to support the shallow wall section and as a vertical support structural member for the basement floor. 2. The column-supported underground continuous wall according to claim 1, characterized in that: the height of the shallow wall (11) is sufficient to cover all unfavorable soil layers. 3. The column-supported underground continuous wall according to claim 2, characterized in that: the shallow wall section extends below the basement floor elevation at the maximum depth of the unfavorable soil body, so as to facilitate the stability of the support system . 4. The column-supported underground continuous wall according to claim 3, characterized in that: the height of the deep wall section is from below the shallow wall section to the rock formation below the bottom of the foundation pit, at the boundary between the shallow wall section and the deep wall section It is set within the range of 300-1500mm below the elevation of the basement floor. 5. The column-supported underground continuous wall according to claim 4, characterized in that: in the part of the deep wall (12), the distance between every two adjacent column-supported walls is 10-30 meters In the range. 6. The column-supported underground continuous wall according to claim 5, characterized in that: in the part of the deep wall (12), the distance between every two adjacent column-supported walls is 15-30 meters In the range. 7. The column-supported underground diaphragm wall according to claim 5, characterized in that: on the inner surface of the underground diaphragm wall (1), several steel bars for connecting the inner walls (6) are pre-embedded, and the inner walls (6) It is formed close to the underground diaphragm wall, and a part of the pre-embedded steel bars of the underground diaphragm wall extends into the inner wall (6), and is fixed in it when the inner wall (6) is poured, so that the two walls are combined as a whole. 8. The pillar-supported underground diaphragm wall according to claim 7, characterized in that: the connecting steel bar (7) for connecting the inner wall (6) is pre-embedded on the inner surface of the underground diaphragm wall (1). During the construction of the inner wall (6), the connecting steel bars pre-buried on the inner surface of the diaphragm wall in the basement are pulled out and extended into the area of the inner wall (6) in the form of "X", and are fixed on the inner wall (6) when it is poured into shape. Wherein, the inner wall (6) is formed close to the underground continuous wall, and the two walls are combined into a whole under the action of the beard tendons. 9. The pillar-supported underground continuous wall according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8, characterized in that two pillars adjacent to the deep wall (12) A shotcrete anchor support combination member (2) is arranged between the walls, and the spray anchor support includes fixing the reinforcement mesh on the side wall of the foundation pit with an anchor rod (22) or soil nails (21) and sprayed concrete, Form a thin wall structure with a certain soil retaining effect. 10. The column-supported underground diaphragm wall according to claim 9, characterized in that: the first floor ring beam (51a) is installed on the top of the shallow wall section of the underground diaphragm wall (1), and the shallow wall (11) The top is provided with longitudinal reinforcement, which is connected with the ring beam (51a) of the first layer; the remaining ring beams of each layer are embedded in the inner wall (6) and poured to form a complete and firm body.

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