Construction method of special-shaped foundation pit of commercial and station complex

Abstract

The invention discloses a construction method for a special-shaped foundation pit of a commercial and station complex, and relates to the technical field of foundation pit construction. Comprising the following steps that S1, a commercial and station complex large foundation pit is divided into six small foundation pits to be sequentially constructed; s2, the foundation pit is excavated into six blocks, and the ground wall of the station body foundation pit reaches the ground; s3, firstly, a first station foundation pit is constructed and excavated, after construction is completed, a sixth foundation pit, a fourth foundation pit, a third foundation pit, a second foundation pit and a fifth foundation pit on the two sides are constructed, and after the first station foundation pit is completed, shield construction of adjacent intervals is synchronously conducted; s4, surface earthwork of the station foundation pit I is excavated firstly, and ring beams and concrete supports are constructed; when the supporting strength of the first concrete reaches the design strength, first-layer earth excavation is started, and slope excavation is carried out according to the gradient smaller than 1: 3 during earth excavation; and S5, commercial foundation pits are excavated, and the excavation sequence is the sixth foundation pit, the fourth foundation pit, the third foundation pit, the second foundation pit and the fifth foundation pit in sequence. According to the construction method of the foundation pit, the water and sand gushing risk in the foundation pit excavation process can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of foundation pit construction, and in particular to a construction method for a special-shaped foundation pit of a commercial and station complex. Background Art

[0002] The existing Sports Park Station is a special-shaped foundation pit for the station and the commercial complex. The station is located in a water-rich silty fine sand stratum. The station base is mainly located in the silty clay layer, and the toe of the underground continuous wall is mainly located in the silty sand and silty soil layer. The geological conditions are poor; the underground groundwater is supplemented by the surrounding water system; the base is located in a weak impermeable layer, and the impermeable layer has been exposed at the end of the long mileage in the impermeable layer, and the groundwater layer is interconnected with the confined water layer.

[0003] The design plan for this type of station is open-cut construction, that is, the construction sequence of "commercial first, then station, small pit in the big pit" is adopted. The risk of foundation pit construction is extremely high, especially the settlement of surrounding buildings and the safety of the foundation pit itself. The probability of leakage and quicksand during the foundation pit excavation is extremely high. Once such a situation occurs, the rescue conditions are extremely unfavorable; at the same time, the construction organization of the combined pit plan is relatively complex and requires a large investment of resources.

[0004] The existing Sports Park Station is a large irregular foundation pit that is excavated all at once to the bottom, and then the structure is backbuilt. There are great risks in the construction of large foundation pits. Therefore, it is necessary to provide a construction method for special-shaped foundation pits for commercial and station complexes that can reduce the risk of water and sand gushing during foundation pit excavation. Summary of the invention

[0005] The main purpose of the present invention is to provide a construction method for special-shaped foundation pits of commercial and station complexes to solve the problems existing in the prior art.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A construction method for a special-shaped foundation pit for a commercial and station complex comprises the following steps:

[0008] S1: Use underground continuous wall as partition wall to divide the large foundation pit of commercial and station complex into 6 small foundation pits for construction in sequence;

[0009] S2: The foundation pit is excavated in six sections, from the main station foundation pit wall to the ground;

[0010] S3: The construction process is to first excavate the station foundation pit 1. After the construction of the station foundation pit 1 is completed, the construction of the foundation pits 6, 4, 3, 2 and 5 on both sides is carried out in sequence. After the completion of the station foundation pit 1, the shield construction of the adjacent sections is carried out simultaneously;

[0011] S4: When the station foundation pit is excavated, the surface earthwork is excavated first, and the ring beam and concrete support are constructed; when the strength of the first concrete support reaches the design strength, the first layer of earthwork excavation begins, and the first, second, third, fourth, fifth, and sixth layers of earthwork are excavated according to the slope less than 1:3;

[0012] S5: Excavation of commercial foundation pits, the excavation order is Pit 6, Pit 4, Pit 3, Pit 2, and Pit 5.

[0013] Furthermore, the standard section of the station foundation pit one has 6 supports, and the end section has 7 supports. The excavation and support erection of the station foundation pit one are carried out in sections and layers. The longitudinal excavation and support erection are divided into eight sections, and the vertical excavation of the east and west end shield shaft sections is divided into seven layers, and the standard section is divided into six layers, except for the surface earth excavation. Each layer of soil in each construction section is excavated in small sections. The platform width of each small section excavation is determined according to the horizontal distance of the support, and the excavation width is not less than 6m; the excavation depth is determined according to the vertical spacing of the support, and the soil at the steel support is constructed by the trenching method; each small section of soil is excavated within 16 hours, and then the support erection and prestressing are completed within 8 hours.

[0014] Furthermore, once the station foundation pit is excavated, the structural construction will be carried out in a timely manner, which is divided into excavation construction and structural backbuilding from both ends to the middle.

[0015] Furthermore, excavation of foundation pit six began after the middle plate of the station foundation pit was closed, and the excavation of the remaining commercial foundation pits was started after the middle plate of the commercial foundation pit was closed.

[0016] Furthermore, the commercial foundation pit excavation method is to first excavate the surface earth, construct ring beams and concrete supports; when the strength of the first concrete support reaches the design strength, start excavating the first layer of earth, excavate to the bottom of the second concrete support, and construct the second concrete support; excavate the second layer of earth to the bottom of the pit, of which the second layer of earth in the low section of the wind pavilion is excavated to the bottom of the third concrete support, and then excavate to the base.

[0017] Furthermore, when the commercial foundation pit is excavated, the first and second layers of earthwork are excavated according to a slope of less than 1:3, and the third layer of earthwork in the low section of the wind pavilion is excavated directly to the bottom.

[0018] Furthermore, the standard section of the commercial foundation pit has 2 concrete supports, the low section of the wind pavilion has 3 concrete supports, and the excavation of the commercial foundation pit and the erection of supports are carried out in sections and layers.

[0019] Furthermore, the longitudinal excavation and support erection of the commercial foundation pit are divided into sections of 15m according to the length of the foundation pit; the vertical excavation is carried out in 2 layers, the low-lying section of the wind pavilion is 3 layers, and each layer of soil in each construction section is excavated in small sections. The excavation width of each small section is not more than 6m, and the excavation depth is determined according to the vertical spacing of the concrete support; each small section of soil is excavated within 16 hours, and then the support erection and prestressing are completed within 8 hours.

[0020] Furthermore, the vertical excavation of the commercial foundation pit first removes the surface soil of the foundation pit to the bottom of the first concrete support, constructs the cap beam and the first concrete support, and starts the excavation of the first layer of earthwork after the concrete support strength reaches the design strength. The first and second layers of earthwork are excavated in sections with a slope of 1:3.

[0021] Furthermore, the support system of the large foundation pit of the commercial and station complex is a structure of underground continuous wall plus internal support.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] Divide the large and irregular foundation pits of commercial and station complexes into multiple small foundation pits to reduce the risk management during the foundation pit excavation process and improve the safety of foundation pit excavation.

[0024] The construction of underground continuous walls in water-rich sand layers can effectively prevent various common defects in underground continuous walls and reduce the risks of water and sand gushing during foundation pit excavation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the construction of a special-shaped foundation pit for a commercial and station complex according to the present invention. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0027] Example

[0028] Combination Figure 1 The present invention provides a construction method for a special-shaped foundation pit of a commercial and station complex, comprising the following steps:

[0029] S1: Use underground continuous wall as partition wall to divide the large foundation pit of commercial and station complex into 6 small foundation pits which are constructed sequentially.

[0030] S2: The foundation pit is excavated in six sections, from the main foundation pit wall of the station to the ground.

[0031] S3: The construction process is to first excavate the station foundation pit one. After the construction of the station foundation pit one is completed, the commercial foundation pits of foundation pit six, foundation pit four, foundation pit three, foundation pit two and foundation pit five on both sides are constructed in sequence. After the completion of the station foundation pit one, the shield construction of the adjacent sections is carried out simultaneously. The excavation of commercial foundation pit six begins after the middle plate of the station foundation pit is closed. The remaining commercial foundation pits are excavated after the middle plate of the commercial foundation pit is closed.

[0032] The standard section of the station foundation pit one has 6 supports, and the end section has 7 supports. The excavation and support erection of the station foundation pit one are carried out in sections and layers. The longitudinal excavation and support erection are divided into eight sections. The vertical excavation of the east and west end shield shaft sections is divided into seven layers, and the standard section is divided into six layers, except for the surface earth excavation. Each layer of soil in each construction section is excavated in small sections. The platform width of each small section excavation is determined according to the horizontal distance of the support, and the excavation width is not less than 6m; the excavation depth is determined according to the vertical spacing of the support, and the soil at the steel support is constructed by the trenching method; each small section of soil is excavated within 16 hours, and then the support is erected and prestressed within 8 hours.

[0033] S4: As soon as the station foundation pit is excavated, the surface earthwork is excavated first, and the ring beam and concrete support are constructed; when the strength of the first concrete support reaches the design strength, the first layer of earthwork excavation begins, and the first, second, third, fourth, fifth and sixth layers of earthwork are excavated according to a slope of less than 1:3; once the station foundation pit is excavated, the structure construction is carried out in a timely manner, divided into excavation construction from both ends to the middle and structural backbuilding.

[0034] S5: Excavation of commercial foundation pits, the excavation order is Pit 6, Pit 4, Pit 3, Pit 2, and Pit 5.

[0035] The commercial foundation pit excavation method is to first excavate the surface earth, construct ring beams and concrete supports; when the strength of the first concrete support reaches the design strength, start excavating the first layer of earth, excavate to the bottom of the second concrete support, and construct the second concrete support; excavate the second layer of earth to the bottom of the pit, of which the second layer of earth in the low section of the wind pavilion is excavated to the bottom of the third concrete support, and then excavate to the base.

[0036] When excavating the commercial foundation pit, the first and second layers of earthwork are excavated according to a slope of less than 1:3, and the third layer of earthwork in the low section of the wind pavilion is excavated directly to the bottom.

[0037] The standard section of the commercial foundation pit has 2 concrete supports, and the low section of the wind pavilion has 3 concrete supports. The excavation of the commercial foundation pit and the erection of supports are carried out in sections and layers.

[0038] The longitudinal excavation and support erection of the commercial foundation pit are divided into sections of 15m according to the length of the foundation pit; the vertical excavation is divided into 2 layers, the low-lying section of the wind pavilion is 3 layers, and each layer of soil in each construction section is excavated in small sections. The excavation width of each small section is not more than 6m, and the excavation depth is determined according to the vertical spacing of the concrete support; each small section of soil is excavated within 16 hours, and then the support erection and prestressing are completed within 8 hours.

[0039] The vertical excavation of the commercial foundation pit first removes the surface soil of the foundation pit to the bottom of the first concrete support, constructs the cap beam and the first concrete support, and starts the first layer of earthwork excavation after the concrete support strength reaches the design strength. The first and second layers of earthwork are excavated in sections with a slope of 1:3.

[0040] The support system of the large foundation pit of the commercial and station complex is an underground continuous wall plus internal support structure.

[0041] Preparation before foundation pit excavation:

[0042] (1) First, relocate and protect the pipelines, remove obstacles within the excavation range, repair the transportation access road within the construction site, and build a car wash station at the entrance and exit. Prepare the conditions for excavation, transportation and abandonment to ensure continuous excavation.

[0043] (2) Complete the acceptance of the ground-anchored wall sub-project before excavation; dewater the foundation pit 20 days before excavation to ensure that there is no water during excavation.

[0044] (3) Organize the entry of construction machinery: assemble and debug according to construction requirements, and put them in place according to the construction sequence; purchase various materials required for the project and stack them according to relevant regulations.

[0045] (4) Install monitoring points properly: During the excavation of the foundation pit, a detailed investigation of the buildings and underground pipelines within 3H (H is the excavation depth) around the station foundation pit is required, and a detailed monitoring and protection plan is prepared. According to the project monitoring requirements, the installation of monitoring points, calibration of monitoring instruments, and reading of initial data are carried out in advance.

[0046] (5) Before foundation pit construction, technical briefings shall be provided to all construction personnel so that they can be familiar with and master the various technical measures and technical standards implemented in this project.

[0047] The surrounding environment and geological conditions of deep foundation pits are complex. During the construction process, safety problems such as foundation pit leakage, deformation, and sudden surges are very likely to occur. It is necessary to divide the large special-shaped foundation pits of stations and commercial complexes into multiple small foundation pits to reduce the risk management during foundation pit excavation and improve the safety of foundation pit excavation.

[0048] The present invention discloses a construction method for a special-shaped foundation pit of a commercial and station complex. Before excavating the foundation pit, the underground continuous wall enclosure structure and the partition wall in the sub-pit are constructed, and the entire complex large foundation pit is divided into 6 small foundation pits. After the water level in each small foundation pit reaches the excavation condition, the excavation and backfilling of each small foundation pit are carried out in turn, and after the middle plate in each foundation pit is closed, the next foundation pit is excavated.

[0049] The present invention divides the large commercial and station complex foundation pit into multiple small foundation pits, reduces the risk management during the foundation pit excavation process, and improves the safety of foundation pit excavation. The construction of underground continuous wall in water-rich sand layer can effectively prevent various common defects in the ground continuous wall and reduce the risk of water and sand gushing during foundation pit excavation.

[0050] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A construction method for a special-shaped foundation pit for a commercial and station complex, characterized in that: The following steps are involved: S1: Use underground continuous wall as partition wall to divide the large foundation pit of commercial and station complex into 6 small foundation pits for construction in sequence; S2: The foundation pit is excavated in six sections, from the main station foundation pit wall to the ground; S3: The construction process is to first excavate the station foundation pit 1. After the construction of the station foundation pit 1 is completed, the construction of the foundation pits 6, 4, 3, 2 and 5 on both sides is carried out in sequence. After the completion of the station foundation pit 1, the shield construction of the adjacent sections is carried out simultaneously; S4: When the station foundation pit is excavated, the surface earthwork is excavated first, and the ring beam and concrete support are constructed; when the strength of the first concrete support reaches the design strength, the first layer of earthwork excavation begins, and the first, second, third, fourth, fifth, and sixth layers of earthwork are excavated according to the slope less than 1:3; S5: Excavation of commercial foundation pits, the excavation order is Pit 6, Pit 4, Pit 3, Pit 2, and Pit 5.

2. The construction method of a special-shaped foundation pit for a commercial and station complex as claimed in claim 1, characterized in that: The standard section of the station foundation pit one has 6 supports, and the end section has 7 supports. The excavation and support erection of the station foundation pit one are carried out in sections and layers. The longitudinal excavation and support erection are divided into eight sections. The vertical excavation of the east and west end shield shaft sections is divided into seven layers, and the standard section is divided into six layers, except for the surface earth excavation. Each layer of soil in each construction section is excavated in small sections. The platform width of each small section excavation is determined according to the horizontal distance of the support, and the excavation width is not less than 6m; the excavation depth is determined according to the vertical spacing of the support, and the soil at the steel support is constructed by the trenching method; each small section of soil is excavated within 16 hours, and then the support is erected and prestressed within 8 hours.

3. The construction method of a special-shaped foundation pit for a commercial and station complex as claimed in claim 2, characterized in that: As soon as the station foundation pit is excavated, structural construction will be carried out in a timely manner, which is divided into excavation construction and structural backbuilding from both ends to the middle.

4. The construction method of a special-shaped foundation pit for a commercial and station complex as claimed in claim 3, characterized in that: Excavation of foundation pit six began after the middle plate of the station foundation pit was closed, and the excavation of the remaining commercial foundation pits began after the middle plate of the commercial foundation pit was closed.

5. The construction method of a special-shaped foundation pit for a commercial and station complex as claimed in claim 4, characterized in that: The commercial foundation pit excavation method is to first excavate the surface earth, construct ring beams and concrete supports; when the strength of the first concrete support reaches the design strength, start excavating the first layer of earth, excavate to the bottom of the second concrete support, and construct the second concrete support; excavate the second layer of earth to the bottom of the pit, of which the second layer of earth in the low section of the wind pavilion is excavated to the bottom of the third concrete support, and then excavate to the base.

6. The construction method of a special-shaped foundation pit for a commercial and station complex as claimed in claim 5, characterized in that: When excavating the commercial foundation pit, the first and second layers of earthwork are excavated according to a slope of less than 1:3, and the third layer of earthwork in the low section of the wind pavilion is excavated directly to the bottom.

7. The construction method of a special-shaped foundation pit for a commercial and station complex as claimed in claim 6, characterized in that: The standard section of the commercial foundation pit has 2 concrete supports, and the low section of the wind pavilion has 3 concrete supports. The excavation of the commercial foundation pit and the erection of supports are carried out in sections and layers.

8. The construction method of a special-shaped foundation pit for a commercial and station complex as claimed in claim 7, characterized in that: The longitudinal excavation and support erection of the commercial foundation pit are divided into sections of 15m according to the length of the foundation pit; the vertical excavation is divided into 2 layers, and the low-lying section of the wind pavilion is 3 layers. Each layer of soil in each construction section is excavated in small sections. The excavation width of each small section is not more than 6m, and the excavation depth is determined according to the vertical spacing of the concrete support; each small section of soil is excavated within 16 hours, and then the support erection and prestressing are completed within 8 hours.

9. The construction method of a special-shaped foundation pit for a commercial and station complex as claimed in claim 8, characterized in that: The vertical excavation of the commercial foundation pit first removes the surface soil of the foundation pit to the bottom of the first concrete support, constructs the cap beam and the first concrete support, and starts the first layer of earthwork excavation after the concrete support strength reaches the design strength. The first and second layers of earthwork are excavated in sections with a slope of 1:

3.

10. The construction method of a special-shaped foundation pit for a commercial and station complex as claimed in claim 1, characterized in that: The support system of the large foundation pit of the commercial and station complex is an underground continuous wall plus internal support structure.

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