CN-117306500-B - Construction method for deep foundation pit of water-rich weak stratum

CN117306500BCN 117306500 BCN117306500 BCN 117306500BCN-117306500-B

Abstract

Aiming at the water-rich weak stratum, the invention explores an underground continuous wall construction method and a deep foundation pit construction method of the water-rich weak stratum based on the underground continuous wall construction method. The TAD construction method is utilized to construct the canal type cutting assembly type underground diaphragm wall at the periphery, so that the effect of rapid water stopping can be achieved, rapid support is formed on the periphery water-rich soft stratum, conditions are provided for cast-in-situ construction of the inner layer cast-in-situ underground diaphragm wall, and the influence of underground water on inner cement and soil can be reduced. Under the protection of the peripheral canal type cutting assembly type underground continuous wall, the cast-in-place construction mode is adopted to cast the inner layer cast-in-place underground continuous wall at intervals, so that the construction efficiency is improved, and meanwhile, the influence of water on cast-in-place concrete can be completely avoided. The designed precast sheet pile can enable the cast-in-place concrete to enter the reserved channel, the canal type cutting assembly type underground continuous wall and the cast-in-situ underground continuous wall are connected into a whole, the thickness and the strength of the whole underground continuous wall are ensured, and the advantage performance of the precast sheet pile and the cast-in-situ continuous wall is integrated.

Inventors

ZHANG GUANHONG
ZHAO HAIFEI
XU ZHIMIN
JIANG TAO
YIN XIAOPENG
SHI SIWEN

Assignees

内蒙古电力勘测设计院有限责任公司

Dates

Publication Date: 20260512
Application Date: 20231101

Claims (8)

1. The construction method of the underground diaphragm wall is characterized by comprising the following steps of: S11, determining the construction width of the underground diaphragm wall to meet the requirements of deep foundation pit enclosure, dividing the underground diaphragm wall into peripheral canal-type cutting assembly type underground diaphragm walls and inner-layer cast-in-situ underground diaphragm walls in the width direction; S12, processing prefabricated sheet piles, wherein the prefabricated sheet piles comprise a main body which is integrally in a cuboid shape, a penetrating type reserved passage is arranged in the main body along the height direction, and a plugging bottom plate is arranged at the bottom of the reserved passage; S13, constructing a canal type cutting assembly type underground continuous wall at the periphery by adopting a TAD construction method, wherein the canal type cutting assembly type underground continuous wall comprises a prefabricated continuous wall formed by connecting prefabricated sheet piles, outer cement soil outside the prefabricated continuous wall and inner cement soil in the prefabricated continuous wall; S14, determining the single maximum excavation length of the cast-in-situ continuous wall soil body, wherein the single maximum excavation length of the cast-in-situ continuous wall soil body refers to the maximum excavation length of the cast-in-situ continuous wall soil body under the condition that the excavation width and depth of the cast-in-situ continuous wall soil body and the channel type cutting assembly type underground continuous wall can stably support peripheral soil bodies are determined; Dividing the cast-in-situ continuous wall soil body into a plurality of sections along the trend, numbering, wherein the length of each section is a single safe excavation length, constructing communication holes for the cast-in-situ continuous wall soil body from the inside of a reserved passage, and performing excavation and cast-in-situ construction work in a spaced excavation mode.
2. The method of claim 1, wherein the peripheral trench cut fabricated underground diaphragm wall has a width smaller than the width of the cast-in-place underground diaphragm wall of the inner layer.
3. The method for constructing the underground diaphragm wall according to claim 1, wherein the upper end and the lower end of the precast sheet pile are fixedly connected with metal joints, the outline of each metal joint is the same as that of the end of the precast sheet pile, steel bars are further arranged on the main body of the precast sheet pile along the height direction, and the ends of the steel bars are connected with the metal joints.
4. The underground diaphragm wall construction method according to claim 1 or 3, wherein one side of the prefabricated sheet pile is provided with a first tenon, a third tenon groove, a second tenon, a third tenon groove and a first tenon in sequence along the width direction, and the other side is provided with the first tenon groove, the third tenon groove, the second tenon groove, the third tenon groove and the first tenon groove in corresponding sequence along the width direction.
5. The method according to claim 4, wherein the second tenons and the second mortises are respectively provided with a first sealing groove and a second sealing groove which are corresponding to each other, the first sealing grooves and the second sealing grooves are butted to form a sealing groove which is sealed in the circumferential direction, and a waterproof plate is placed in the sealing groove.
6. The underground diaphragm wall construction method according to claim 1 or 3, wherein a groove-shaped space with a set width and depth is dug out on the ground by a TRD machine, cement soil is formed by synchronous grouting, a plurality of prefabricated sheet piles connected with each other in the height direction are lifted up together and inserted into the cement soil, and adjacent prefabricated sheet piles are sequentially inserted into the cement soil along the trend direction through mortise and tenon structures to form the prefabricated diaphragm wall.
7. The method according to claim 1 or 3, wherein the odd-numbered sections are excavated first, and the continuous wall soil construction communication holes are cast in situ from the inside of the reserved passage, and the concrete is cast in situ, and the even-numbered sections are excavated, and the continuous wall soil construction communication holes are cast in situ from the inside of the reserved passage, and the concrete is cast in situ.
8. A construction method of a deep foundation pit of a water-rich weak stratum comprises the following steps: s1, constructing an underground diaphragm wall enclosure structure by adopting the underground diaphragm wall construction method according to any one of claims 1-7; s2, excavating earthwork layer by layer, constructing a crown beam, a concrete retaining wall, an anchor rope and a waist beam, and arranging drainage ditches and water collecting wells around the foundation pit.

Description

Construction method for deep foundation pit of water-rich weak stratum Technical Field The invention belongs to the field of foundation pits, and particularly relates to an underground continuous wall construction method and a deep foundation pit construction method for a water-rich weak stratum based on the underground continuous wall construction method, which are suitable for the construction of the water-rich weak stratum, in particular to the deep foundation pit. Background The underground diaphragm wall is a common enclosure structure in foundation pit engineering and is mainly divided into a prefabricated underground diaphragm wall and a cast-in-situ underground diaphragm wall, wherein the prefabricated underground diaphragm wall is prefabricated on the ground, is slightly influenced by external factors during maintenance, has high wall forming quality, and has high construction speed, but has poor adaptability to geological conditions. The water-rich weak stratum is one of geological terrains commonly encountered in foundation pit construction, and due to the fact that soil bodies are weak, the construction thickness of the continuous wall is generally relatively wide so as to provide sufficient support for the weak soil bodies, especially under the condition of deep foundation pit construction. Aiming at water-rich weak stratum, the prefabricated underground continuous wall has certain advantages, and can avoid the influence of water on concrete maintenance. The TAD construction method in the prior art, also called as canal cutting assembly type underground diaphragm wall construction method, is a construction process for forming an assembly type underground diaphragm wall by embedding reinforced concrete prefabricated parts into canal cutting cement soil diaphragm walls, has the advantages of small occupied space, strong adaptability, quick construction and the like, and can be used for water-rich stratum. However, the TRD machine used in the TAD method is generally of a specific model, the width of the constructed continuous wall is limited to a certain extent, and when the construction width is large, a relatively wide prefabricated sheet pile needs to be prepared, which is not beneficial to construction work such as lifting and verticality control, and cement soil on two sides of the prefabricated plate is still affected by stratum water, so that cement soil is lost, and the problem of low strength of the continuous wall formed by cement soil is caused. Disclosure of Invention In order to solve the problems of low construction efficiency and insufficient construction strength of an underground diaphragm wall during construction of a deep foundation pit in a water-rich and weak stratum, the invention combines a TAD construction method with a cast-in-situ underground diaphragm wall, and explores a construction method of the underground diaphragm wall in the water-rich and weak stratum and a construction method of the deep foundation pit in the water-rich and weak stratum based on the construction method of the underground diaphragm wall, which are suitable for construction of the deep foundation pit in the water-rich and weak stratum, especially for the construction of the deep foundation pit, and can ensure the construction strength of the underground diaphragm wall, and the concrete technical scheme of the invention is as follows: a construction method of an underground continuous wall comprises the following steps: S11, determining the construction width of the underground diaphragm wall to meet the requirements of deep foundation pit enclosure, dividing the underground diaphragm wall into peripheral canal-type cutting assembly type underground diaphragm walls and inner-layer cast-in-situ underground diaphragm walls in the width direction; S12, processing prefabricated sheet piles, wherein each prefabricated sheet pile comprises a main body which is integrally cuboid, a penetrating type reserved passage is arranged in the main body along the height direction, and a plugging bottom plate is arranged at the bottom of the reserved passage; S13, constructing a canal type cutting assembly type underground continuous wall at the periphery by adopting a TAD construction method, wherein the canal type cutting assembly type underground continuous wall comprises a prefabricated continuous wall formed by connecting prefabricated sheet piles, outer cement soil outside the prefabricated continuous wall and inner cement soil in the prefabricated continuous wall; S14, determining the single maximum excavation length of the cast-in-situ continuous wall soil body, wherein the single maximum excavation length of the cast-in-situ continuous wall soil body refers to the maximum excavation length of the cast-in-situ continuous wall soil body under the condition that the excavation width and depth of the cast-in-situ continuous wall soil body and the channel type cutting assembly type underground continuous wall ca