CN114991219A

CN114991219A - Anti-seepage structure for ground wall joint position in ultra-deep foundation pit engineering and construction method

Info

Publication number: CN114991219A
Application number: CN202210674844.9A
Authority: CN
Inventors: 翁其平; 李靖; 王卫东; 戴斌
Original assignee: East China Architectural Design and Research Institute Co Ltd
Current assignee: East China Architectural Design and Research Institute Co Ltd
Priority date: 2022-06-15
Filing date: 2022-06-15
Publication date: 2022-09-02

Abstract

The invention belongs to an anti-seepage structure and a construction method for a ground wall joint position in ultra-deep foundation pit engineering in the field of urban underground space development. The technical scheme is as follows: an interface exists between the first underground continuous wall and the second underground continuous wall; a first steel reinforcement cage of the first underground continuous wall and a second steel reinforcement cage of the second underground continuous wall are respectively provided with a first water-stopping embedded part and a second water-stopping embedded part at the positions, close to the interface, of the inner side of the foundation pit; the bottoms of the first water stopping embedded part and the second water stopping embedded part extend to the base position of the foundation pit; the stagnant water steel sheet sets up the seepage position at the interface, and the both sides of stagnant water steel sheet are buried the piece and are welded with first stagnant water respectively with the second stagnant water. The structure and the construction method are applied to the development of the ultra-deep underground space in the high underground water level center urban area, the risk of water leakage of the underground diaphragm wall can be effectively reduced, and further the influence of foundation pit excavation on the surrounding environment is reduced.

Description

Anti-seepage structure for ground wall joint position in ultra-deep foundation pit engineering and construction method

Technical Field

The invention belongs to the field of urban underground space development, and particularly relates to a reinforced water stop structure and a construction method in the development of an ultra-deep underground space in an urban area of a high-groundwater-level center, which can ensure the effective protection of the surrounding environment and the safe and smooth implementation of foundation pit engineering.

Background

With the acceleration of the urbanization process, many cities begin to seek opportunities for space expansion towards deep underground spaces under the condition that shallow underground space development tends to be saturated. New projects for deep underground spaces have emerged with increasing space requirements for cities, expanding city capacity in the vertical direction. Shanghai is one of cities with early underground space development and utilization in China, and the utilization of deep underground space is ahead of most cities in China. At present, the subway station in the Shanghai region reaches more than 40 meters underground, and the depth of a foundation pit of the world expo transformer substation reaches 34 meters underground. The north cross channel of the upper sea, which is the second main artery of the east-west direction of the upper sea, has also reached 48 meters in depth using the underground space, and a section of the underground portion exceeding 40 meters in depth reaches 2.6 kilometers. In addition, a major project, namely construction of a Suzhou river section deep drainage storage regulating pipeline system project, is carried out in the Shanghai region, wherein the test section project implemented in advance is a nursery garden-Yunling section first-level storage regulating pipeline and matched comprehensive facilities, the total length is about 1.67km, and the depths of vertical shaft foundation pits at two ends are close to the excavation depth of 60 m.

Due to the outstanding advantages of large rigidity, deep wall forming depth, reliable quality and the like, the underground continuous wall is the most widely applied enclosure structure form in ultra-deep foundation pit construction at present. The construction process of the underground continuous wall needs to be implemented successively in different groove sections, and the joint positions among the groove sections of the underground continuous wall often become weak nodes of water leakage. Particularly, for ultra-deep foundation pit engineering, the stratum conditions are more complicated, and the problem of water leakage at the position of a ground wall joint is more prominent in the stratum with stronger water permeability. Leakage water occurs in foundation pit engineering, on one hand, the water level outside the pit is reduced, and then soil outside the pit is solidified and settled; on the other hand, fine-grained silt can enter the pit along with the leakage water, so that soil outside the pit can be lost. Therefore, if water leakage occurs in the foundation pit engineering, the surrounding ground surface is inevitably settled, and the safety of surrounding structures, roads and underground pipelines is threatened. Meanwhile, the safe and smooth construction of foundation pit engineering is greatly influenced by the water leakage of the underground diaphragm wall. In recent years, safety accidents such as inclination cracking of surrounding buildings and road collapse due to water leakage from foundation pits have been continued. At present, the most common solution is to separately set a waterproof curtain on the outer side of the ground wall, or to set a waterproof structure measure at the joint position on the outer side of the ground wall, but the existing technical measure cannot completely avoid the problem of water leakage of the ground wall, and the manufacturing cost of the foundation pit enclosure structure is greatly increased.

Disclosure of Invention

In order to solve the technical problems, the invention provides an anti-seepage structure and a construction method for a ground wall joint position in ultra-deep foundation pit engineering.

The technical scheme of the invention comprises two methods.

The first technical scheme is as follows: an anti-seepage structure for a ground wall joint position in ultra-deep foundation pit engineering is disclosed, wherein an underground continuous wall comprises a first underground continuous wall constructed in an early stage and a second underground continuous wall constructed in a later stage, and an interface exists between the first underground continuous wall and the second underground continuous wall; a first steel reinforcement cage of the first underground continuous wall and a second steel reinforcement cage of the second underground continuous wall are respectively provided with a first water-stopping embedded part and a second water-stopping embedded part at the positions, close to the interface, of the inner side of the foundation pit; the bottoms of the first water stopping embedded part and the second water stopping embedded part extend to the position of the foundation pit base; the stagnant water steel sheet sets up the seepage position at the interface, and the both sides of stagnant water steel sheet weld with first stagnant water buries piece and second stagnant water buries the piece respectively.

Based on the technical characteristics: and a compressible water stopping material is arranged between the water stopping steel plate and the wall surface of the underground continuous wall.

Based on the technical characteristics: the surface of the water stop steel plate is provided with holes and is provided with a drainage filter screen.

The construction method of the anti-seepage structure based on the technical scheme comprises the following steps:

step 1: respectively welding a first water-stopping embedded part and a second water-stopping embedded part at positions of the first reinforcement cage and the second reinforcement cage close to the adjacent interface of the inner side of the foundation pit;

and 2, step: after the grooving of the underground continuous wall is finished, a first reinforcement cage with a first water-stop embedded part and a second reinforcement cage with a second water-stop embedded part are together put into the groove section of the underground continuous wall; sequentially pouring the first underground continuous wall and the second underground continuous wall;

and step 3: when the foundation pit is excavated to a stratum with strong water permeability, fixing a water stop steel plate at the leakage position of the interface; two sides of the water stop steel plate are respectively welded with the first water stop embedded part and the second water stop embedded part; and a compressible water stopping material is arranged between the underground continuous wall and the water stopping steel plate.

Based on the technical characteristics: and step 3, pre-drilling holes on the water stop steel plate, and arranging a drainage filter screen in the holes.

The second technical scheme is as follows: the underground continuous walls comprise a first underground continuous wall constructed in the early period and a second underground continuous wall constructed in the later period, and an interface exists between the first underground continuous wall and the second underground continuous wall; the first underground continuous wall is a rigid joint, and a second steel reinforcement cage of the second underground continuous wall is provided with a second water stop embedded part at the position, close to the interface, of the inner side of the foundation pit; the bottom of the second water stop embedded part extends to the position of the foundation pit base; the water stop steel plate is arranged at the leakage position of the interface, and the two sides of the water stop steel plate are respectively welded with the rigid joint and the second water stop embedded part.

The construction method based on the second anti-seepage structure of the technical scheme comprises the following steps:

step 1: welding a second water-stop embedded part at a position, close to the inner side of the foundation pit and adjacent to the interface, of the second reinforcement cage;

step 2: after the grooving of the underground continuous wall is finished, the rigid joint and a second reinforcement cage with a second water stop embedded part are together put into the groove section of the underground continuous wall; sequentially pouring the first underground continuous wall and the second underground continuous wall;

and step 3: when the foundation pit is excavated to a stratum with strong water permeability, fixing a water stop steel plate at the leakage position of the interface; two sides of the water stop steel plate are respectively welded with the rigid joint and the second water stop embedded part; and a compressible water stopping material is arranged between the underground continuous wall and the water stopping steel plate.

For the underground continuous wall in the form of the conventional fore shaft pipe joint, an interface is inevitably formed between the underground continuous wall constructed in the early stage and the underground continuous wall constructed in the later stage. In the construction process of the ultra-deep foundation pit in the high underground water level area, particularly when the foundation pit is excavated to a stratum with stronger water permeability, the interface of the two underground continuous walls often becomes a weak link for water leakage. The water stop embedded part is arranged on the reinforcement cage close to the interface at the inner side of the foundation pit, and when water leakage occurs in the underground diaphragm wall, the water stop steel plate is welded in time, so that the water leakage can be quickly blocked. As the surface of the underground continuous wall is uneven in actual construction, compressible water stopping materials such as foam plastics or rubber sheets can be placed between the water stopping steel plate and the underground continuous wall, and the reliability of water stopping is further ensured. Through the construction measure, the leakage position can be effectively blocked in time, so that the underground water level outside the foundation pit can not be reduced and the soil body can not be lost due to the leakage of the underground diaphragm wall in the process of excavation of the foundation pit and precipitation in the pit, and the peripheral building, roads and underground pipelines can not generate large additional deformation due to stratum settlement. Meanwhile, the technology can also reduce the construction cost of the foundation pit enclosure increased by independently adding the waterproof curtain. When the stratum water yield of seepage position place is very abundant, the great water yield leads to the direct coverage stagnant water steel sheet to be difficult for the construction, but under the local seepage can not cause the circumstances that the water level descends outside the hole, can trompil on the stagnant water steel sheet to at downthehole drainage filter screen that sets up. The drainage filter screen has the functions of preventing fine-particle silt outside the pit from entering the pit along with leakage water, so that stratum settlement caused by loss of soil outside the pit is prevented; on the other hand, the quick construction of the welding connection between the water stop steel plate and the water stop embedded part can be ensured.

The beneficial effects of the invention are as follows: firstly, the settlement of peripheral stratums caused by water leakage of underground continuous walls can be avoided in the construction process of foundation pit engineering, and the safety of peripheral building structures, roads and underground pipelines can be further ensured; secondly, the technical measures can ensure that when the underground continuous wall has the problem of water leakage, effective plugging treatment can be carried out in time, and the normal construction of the foundation pit is ensured; in addition, the waterproof curtain measures on the outer side of the conventional underground continuous wall can be further optimized by adopting the technical measures, so that the construction cost is saved.

Drawings

Fig. 1 is a schematic plan view of the construction measures of the underground diaphragm wall and the joint water-stop seepage-proofing node in the first technical scheme of the invention.

Fig. 2 is a schematic view of the vertical arrangement of the underground diaphragm wall and the joint water-stop seepage-proofing node construction measures in the first technical scheme of the invention.

Fig. 3 is a schematic plan view of the construction measures of the underground diaphragm wall and the joint water-stop seepage-proofing node in the second technical scheme of the invention.

The reference numbers in the figures denote: a first underground diaphragm wall 1; a second underground continuous wall 2; an interface 3; a first reinforcement cage 41; a second reinforcement cage 42; a first water stopping buried member 51; a second water stop buried member 52; a foundation pit base position 6; a highly water permeable formation 7; a water stop steel plate 8; a compressible water stop material 9; a drainage strainer 10; an H-shaped steel joint structure 11.

Detailed Description

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings. These embodiments are merely illustrative of the present invention and are not intended to limit the present invention.

In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; may be a mechanical connection; the two components can be directly connected or indirectly connected through an intermediate medium, and the two components can be communicated with each other. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.

The anti-seepage structure is arranged at the position of the ground wall joint in the ultra-deep foundation pit engineering, so that the safety of surrounding building structures, roads and underground pipelines in the construction process of the foundation pit engineering can be ensured; the method ensures that the underground continuous wall can be effectively blocked and treated in time when the problem of water leakage occurs, and ensures the normal construction of the foundation pit; meanwhile, waterproof curtain measures on the outer side of the conventional underground diaphragm wall can be optimized, and the construction cost is saved. The following two technical schemes are specifically explained by combining the accompanying drawings respectively:

first, technical scheme

As shown in fig. 1 to 2, an interface 3 between a first underground continuous wall 1 constructed in advance and a second underground continuous wall 2 constructed in later stage often becomes a weak link of water leakage in the process of excavation construction of a foundation pit; arranging water-stop buried parts at positions, close to the interface 3, of the inner sides of foundation pits, of reinforcement cages of a first underground continuous wall 1 constructed in the early stage and a second underground continuous wall 2 constructed in the later stage; namely, a first water stop embedded part 51 is arranged at the first reinforcement cage 41 of the first underground continuous wall 1; a second water stop insert 52 is provided at the second reinforcement cage 42 of the second underground diaphragm wall 2.

The water-stopping embedded part is connected with a reinforcement cage of the underground continuous wall to form a whole, after grooving of the underground continuous wall is finished, the water-stopping embedded part and the reinforcement cage are together transferred into a groove section of the underground continuous wall, and the bottom depths of the first water-stopping embedded part 51 and the second water-stopping embedded part 52 are the same as the position 6 of the foundation pit base. In the subsequent excavation process of the foundation pit, when the foundation pit is excavated to a stratum 7 with strong water permeability, the problem of water leakage often occurs at the position of an interface 3 between a first underground continuous wall 1 constructed in the previous period and a second underground continuous wall 2 constructed in the later period, at this time, a water stop steel plate 8 can be arranged at the position where the water leakage occurs, and the water stop steel plate 8 is respectively connected with the first water stop embedded part 51 and the second water stop embedded part 52 through welding to complete the leakage plugging construction; the top and the bottom of the water stop steel plate 8 are covered with the stratum 7 with strong water permeability. The highly permeable stratum 7 is typically silt or sandy soil; or strong water permeability of the soil layer due to external environmental reasons, such as geographical reasons of being arranged at the edge of a river, etc.

Due to the fact that the surface of the underground continuous wall is not flat, a compressible water stopping material 9 is arranged between the water stopping steel plate 8 and the underground continuous wall.

When the water amount at the leakage position of the interface 3 is large, a hole is formed on the water stop steel plate 8 at the corresponding position, and a drainage filter screen 10 is arranged in the hole. After the water stop steel plate 8 and the water stop embedded part 5 are connected, the leaked water can be guided and drained through the drainage filter screen 10, and then the water can be naturally drained out of the water stop steel plate 8 through the drainage filter screen 10; measures can be taken to close the drainage screen 10, i.e. to block the openings in the water-stop steel plate 8.

Second, technical scheme two

As shown in fig. 3, the first underground diaphragm wall 1 is a rigid joint, and as shown in fig. 3, the H-beam joint structure 11, the interface 3 between the pre-constructed underground diaphragm wall 1 and the post-constructed underground diaphragm wall 2 also becomes a weak link for water leakage. In this case, the second water stop buried member 52 is only required to be arranged at a position close to the interface 3 of the second reinforcement cage 42 of the second underground continuous wall 2 constructed at a later stage. The water stop steel plate 8 is arranged at the leakage position of the interface 3, and both sides of the water stop steel plate 8 are respectively welded with the H-shaped steel joint structure 11 and the second water stop embedded part 52.

The construction method comprises the following steps: the H-shaped steel joint structure 11 and the second reinforcement cage 42 of the first underground continuous wall 1 constructed in advance are connected into a whole and are put into the groove section of the underground continuous wall together; at this time, the second water stop embedded part 52 is only required to be arranged at the end part of the reinforcement cage 4 of the second underground continuous wall 2 constructed in the later period; when the foundation pit is excavated to the stratum 7 with strong water permeability, if the problem of water leakage occurs, arranging a water stop steel plate 8 at the position where the water leakage occurs; one end of the water stop steel plate 8 is connected with the H-shaped steel joint structure 11, and the other end is connected with the second water stop embedded part 52; due to the fact that the surface of the underground continuous wall is not flat, a compressible water stopping material 9 is arranged between the water stopping steel plate 8 and the underground continuous wall.

Of course, the water stop steel plate 8 may be perforated and the drainage filter screen 10 may be disposed in the hole, similarly to the first embodiment.

In conclusion, by adopting the technical measure of arranging the anti-seepage node structure at the position of the ground wall joint in the ultra-deep foundation pit engineering, the invention can firstly ensure that the peripheral stratum can not be settled due to the water leakage of the ground wall in the construction process of the foundation pit engineering, thereby ensuring the safety of peripheral building structures, roads and underground pipelines; secondly, the technical measures can ensure that when the underground continuous wall has the problem of water leakage, effective plugging treatment can be carried out in time, and the normal construction of the foundation pit is ensured; in addition, the waterproof curtain measures on the outer side of the conventional underground continuous wall can be further optimized by adopting the technical measures, so that the construction cost is saved.

The above is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and substitutions can be made without departing from the technical principle of the present invention, and these modifications and substitutions should also be regarded as the protection scope of the present invention.

Claims

1. An impermeable construction for a ground wall joint position in ultra-deep foundation pit engineering, an underground continuous wall comprises a first underground continuous wall (1) constructed in advance and a second underground continuous wall (2) constructed in later period, and an interface (3) exists between the first underground continuous wall (1) and the second underground continuous wall (2); the method is characterized in that: a first water stop embedded part (51) and a second water stop embedded part (52) are respectively arranged at the positions, close to the interface (3), of a first reinforcement cage (41) of the first underground continuous wall (1) and a second reinforcement cage (42) of the second underground continuous wall (2) on the inner side of the foundation pit; the bottoms of the first water stopping embedded part (51) and the second water stopping embedded part (52) extend to a foundation pit base position (6); the water stop steel plate (8) is arranged at the leakage position of the interface (3), and the two sides of the water stop steel plate (8) are respectively welded with the first water stop embedded part (51) and the second water stop embedded part (52).

2. The anti-seepage construction for the ground wall joint position in the ultra-deep foundation pit engineering according to claim 1, characterized in that: and a compressible water stopping material (9) is arranged between the water stopping steel plate (8) and the wall surface of the underground continuous wall.

3. The seepage-proofing structure for the ground wall joint position in the ultra-deep foundation pit engineering according to claim 1 or 2, wherein: the surface of the water stop steel plate (8) is provided with holes and is provided with a drainage filter screen (10).

4. The construction method of an impermeable construction according to claim 1, characterized in that:

step 1: welding the first water stop buried part (51) and the second water stop buried part (52) at positions, close to the interface (3) on the inner side of the foundation pit, of the first reinforcement cage (41) and the second reinforcement cage (42) respectively;

and 2, step: after the underground continuous wall is grooved, the first reinforcement cage (41) with the first water-stop buried part (51) and the second reinforcement cage (42) with the second water-stop buried part (52) are together lowered into the groove section of the underground continuous wall; successively pouring the first underground continuous wall (1) and the second underground continuous wall (2);

and step 3: when the foundation pit is excavated to a strong water permeability stratum (7), fixing the water stop steel plate (8) at the leakage position of the interface (3); two sides of the water stop steel plate (8) are respectively welded with the first water stop embedded part (51) and the second water stop embedded part (52); and a compressible water stopping material (9) is arranged between the underground continuous wall and the water stopping steel plate (8).

5. The construction method of an impermeable construction according to claim 4, characterized in that: in the step 3, a hole is formed in the water stop steel plate (8) in advance, and a drainage filter screen (10) is arranged in the hole.

6. An anti-seepage structure for a ground wall joint position in ultra-deep foundation pit engineering is disclosed, an underground continuous wall comprises a first underground continuous wall (1) constructed in advance and a second underground continuous wall (2) constructed in later period, and an interface (3) exists between the first underground continuous wall (1) and the second underground continuous wall (2); the method is characterized in that: the first underground continuous wall (1) is a rigid joint, and a second steel reinforcement cage (42) of the second underground continuous wall (2) is provided with a second water stop buried part (52) at the position, close to the interface (3), of the inner side of the foundation pit; the bottom of the second water stop embedded part (52) extends to a foundation pit base position (6); the water stop steel plate (8) is arranged at the leakage position of the interface (3), and two sides of the water stop steel plate (8) are respectively welded with the rigid joint and the second water stop embedded part (52).

7. The seepage-proofing structure for the ground wall joint position in the ultra-deep foundation pit engineering according to claim 6, wherein: and a compressible water stopping material (9) is arranged between the water stopping steel plate (8) and the wall surface of the underground continuous wall.

8. An impermeable construction for a ground wall joint position in ultra-deep foundation pit engineering according to claim 6 or 7, characterized in that: the surface of the water stop steel plate (8) is provided with holes and is provided with a drainage filter screen (10).

9. The construction method of an impermeable construction according to claim 7, characterized in that:

step 1: welding the second water stop buried part (52) at a position, close to the interface (3), on the inner side of the foundation pit, of the second reinforcement cage (42);

step 2: after the underground continuous wall is grooved, the rigid joint and the second reinforcement cage (42) with the second water stop embedded part (52) are together lowered into the groove section of the underground continuous wall; successively pouring the first underground continuous wall (1) and the second underground continuous wall (2);

and step 3: when the foundation pit is excavated to a strong water permeability stratum (7), fixing the water stop steel plate (8) at the leakage position of the interface (3); two sides of the water stop steel plate (8) are respectively welded with the rigid joint and the second water stop embedded part (52); and a compressible water stopping material (9) is arranged between the underground continuous wall and the water stopping steel plate (8).

10. The construction method of an impermeable construction according to claim 9, characterized in that: in the step 3, a hole is formed in the water stop steel plate (8) in advance, and a drainage filter screen (10) is arranged in the hole.