A method for cover-excavation top-down construction over existing pipelines

Abstract

The application discloses a cover-excavation top-down construction method of covering existing pipelines, and comprises the following steps: constructing a retaining diaphragm wall around a subway station, and constructing a steel pipe concrete column in the middle of the subway station; newly constructing a standby pipeline, and then connecting the existing pipeline to the standby pipeline; excavating and constructing a south roof and a north roof respectively; restoring the existing pipeline, and covering soil on the south roof; and constructing a main body structure by using a cover-excavation top-down method. The construction method can construct the south roof and the north roof respectively, and the traffic in the south roof area can be restored after the construction of the south roof is completed; only a soil hole needs to be reserved for the north roof, the enclosed area is small, the construction efficiency is high, the subsequent main body project is constructed by using the cover-excavation top-down method, and the occupation of the ground can be reduced to the maximum extent; the existing pipeline is connected to the standby pipeline in the construction process of the south roof, the normal use of the pipeline can be ensured, the limitation of the existing pipeline on the construction of the south roof can be avoided, and the construction efficiency can be further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of building construction, in particular to a cover-over existing pipeline cover-dig top-down construction method. BACKGROUND

[0002] Cover-dig top-down method is a new type of engineering construction method when underground engineering is constructed and needs to pass through roads, buildings and other obstacles. The top part is closed after excavation to a certain depth, and the remaining lower part is constructed under the closed top cover. Cover-dig top-down method is suitable for loose geological conditions and areas where the tunnel is above the groundwater level. This method only blocks ground traffic for a short time; but it is not convenient to excavate, the construction space is small, the construction speed is slow, the construction period is long, and the cost is high.

[0003] When the subway station construction site is selected to have pipelines, it is usually necessary to choose to avoid, for example, patent ZL202010044059.6 "Pipe cover-dig top-down construction method for subway station construction", which selects to avoid the existing pipeline on one side, then sets up a pipe cover to form a shed structure under the pipeline, and then constructs below. However, for some transportation hub areas, the underground pipeline is complex, and it is not possible to effectively avoid the existing pipeline, so the existing cover-dig top-down method cannot be effectively constructed. SUMMARY

[0004] In view of the above problems, the present application aims to provide a cover-over existing pipeline construction method suitable for the cover-dig top-down method of the entry-exit line transition single column section.

[0005] To achieve this technical purpose, the present application provides a cover-dig top-down construction method for overlying existing pipelines. A diaphragm wall is constructed around the subway station, and a steel pipe concrete column is constructed in the middle of the subway station. A new standby pipeline is constructed, and then the existing pipeline is connected to the standby pipeline. The south side roof and the north side roof are excavated and constructed respectively. The existing pipeline is restored, and the soil is covered on the south side roof. The main structure is constructed by cover-dig top-down method.

[0006] As a preferred, the specific steps are as follows:

[0007] S1, a standby pipeline is newly constructed on the north side of the existing pipeline;

[0008] Foundation piles and steel pipe concrete columns are arranged between the diaphragm walls, and a split diaphragm wall is constructed on the north side of the steel pipe concrete column. The split diaphragm wall serves as a temporary enclosure structure for south side excavation and construction, and finally the dewatering is performed.

[0009] S2, the existing pipeline is connected to the standby pipeline on the north side, the south side of the foundation pit of the split diaphragm wall is excavated to the specified position, and then the first steel support is erected, excavated to the design elevation; the south side of the subway station roof is constructed, and the waterproof layer is laid on the south side of the roof after the south side of the roof reaches the design strength; the topsoil is covered on the south side of the roof, and the existing pipeline is buried at the same time;

[0010] S3, construction on the north side of the split diaphragm wall, after excavating to the specified position, remove the first steel support on the south side and retain the topsoil retaining wall, erect the second steel support on the north side of the topsoil retaining wall, and restore the standby pipeline to the existing pipeline.

[0011] S4, continue construction on the north side of the subway station, excavate while breaking the split diaphragm wall and the standby pipeline, and excavate to the design elevation;

[0012] S5, construction of the north side of the subway station roof is made on the north side of the south side of the roof, and the topsoil hole is reserved on the north side of the roof, and the topsoil retaining wall is retained, and the waterproof layer is laid on the north side of the roof after the north side of the roof reaches the specified design strength, then the topsoil is covered on the north side of the roof, and the second steel support is removed;

[0013] S6, using the cover-excavation reverse method, excavate from the topsoil hole to the specified elevation of the negative one layer, and construct the negative one side wall, the negative one side wall waterproof layer and the negative one layer plate of the subway station; continue to excavate to the specified elevation of the negative two layer, and construct the negative two side wall, the negative one side wall waterproof layer and the negative two layer plate of the subway station;

[0014] S7, continue to use the cover-excavation reverse method to excavate to the design pit bottom elevation, construct the cushion, bottom plate waterproof layer and bottom plate, construct the negative three side wall waterproof layer, negative three side wall and negative three partition wall, that is, the main structure of the station is completed.

[0015] As a preferred, the south side of the roof is constructed in step S2 before the completion of the construction of the south side of the roof, and the traffic of the south side of the roof area is restored after the restoration of the standby pipeline to the existing pipeline in step S3.

[0016] As a preferred, the south side of the roof is backfilled in step S2 after reaching 100% of the design strength;

[0017] In step S6, the negative one layer plate, the negative one side wall, the negative two layer plate and the negative two side wall reach 100% of the design strength before the next step of excavation construction.

[0018] As a preferred, the backfilling construction process of the south side of the roof in step S2 should be uniform and symmetrical, and should be layered and tamped to protect the waterproof layer and the existing pipeline.

[0019] As a preferred, after the installation of the steel pipe concrete column in step S1 is completed, the fine sand between the steel pipe concrete column and the pile hole is backfilled and compacted.

[0020] As preferred, a temporary support beam is erected between the negative second floor and the steel pipe concrete column in step S6 for transferring horizontal force and vertical force;

[0021] Auxiliary support columns are further arranged between the negative second floor and the negative first floor and between the negative second floor and the bottom plate, and auxiliary support beams are further arranged between the auxiliary support columns and the steel pipe concrete columns.

[0022] The construction method of the present application separately constructs the south side roof and the north side roof, and the traffic in the south side roof area can be restored after the construction of the south side roof is completed, and only a soil hole needs to be reserved for the north side roof, the enclosed area is small, the construction efficiency is high, and the subsequent main body engineering is constructed by the top-down method to minimize the occupation of the ground; during the construction of the south side roof, the existing pipeline is connected to the standby pipeline, which can not only ensure the normal use of the pipeline, but also avoid the limitation of the existing pipeline on the construction of the south side roof, and further improve the construction efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 Reference is made to the figure for the state of step S1 of the present application;

[0024] Figure 2 Reference is made to the figure for the state of step S2 of the present application;

[0025] Figure 3 Reference is made to the figure for the state of step S3 of the present application;

[0026] Figure 4 Reference is made to the figure for the state of step S4 of the present application;

[0027] Figure 5 Reference is made to the figure for the state of step S5 of the present application;

[0028] Figure 6 Reference is made to the figure for the state of step S6 of the present application;

[0029] Figure 7 Reference is made to the figure for the state of step S7 of the present application;

[0030] Figure 8 Reference is made to the figure for the construction state of the top view of steps S1-S4 of the present application. DETAILED DESCRIPTION

[0031] The present application will be further described in detail below in combination with the drawings and specific embodiments. In order to clearly and completely describe the technical solutions, the following embodiments are selected for description; the following embodiments are part of the embodiments of the present application; other embodiments obtained based on the present application without creative labor are also within the scope of protection of the present application.

[0032] In the following embodiments, it should be noted that the terms "upper", "lower", "left", "right", "inner", "outer", "top / bottom" and other orientation or position relationships are based on the orientation or position relationships shown in the drawings, and are only for the convenience of clearly describing the embodiments, and do not indicate or imply that the devices or elements referred to must have a particular orientation, so it cannot be understood as a limitation on the present application. At the same time, "first", "second" in the embodiments are only used for distinguishing description purposes, and do not represent relative importance.

[0033] The specific embodiment of the present application is a cover-excavation top-down construction method for overlying existing pipelines, a fender diaphragm wall is constructed around the subway station, and a steel pipe concrete column is constructed in the middle of the subway station; a new standby pipeline is built, and then the existing pipeline is connected to the standby pipeline; the south side roof and the north side roof are excavated and constructed respectively; the existing pipeline is restored, and the soil is covered on the south side roof; the main structure is constructed by using the cover-excavation top-down method.

[0034] Embodiment one

[0035] As shown in Figures 1-8 , a cover-excavation top-down construction method for overlying existing pipelines, the specific steps are as follows:

[0036] S1, a standby pipeline 3 is newly built on the north side of the existing pipeline 4, and a fender diaphragm wall 1 is constructed around the subway station as the fender structure of the subway station;

[0037] Foundation piles 7 and steel pipe concrete columns 2 are arranged between the fender diaphragm walls 1, and a split diaphragm wall 8 is constructed on the north side of the steel pipe concrete column 2, which serves as a temporary fender structure for the excavation construction on the south side, and finally the dewatering is performed; after the steel pipe concrete column is installed, the fine sand between the steel pipe concrete column and the pile hole is backfilled and compacted.

[0038] S2, the existing pipeline 4 is connected to the standby pipeline 3 on the north side, the south side foundation pit of the split diaphragm wall 8 is excavated to the specified position, then the first steel support 9 is erected, and the excavation is performed to the design elevation; the south side roof 5 of the subway station is constructed, the south side roof can be backfilled and covered after reaching 100% of the design strength; a waterproof layer is laid on the south side roof 5, and a roof retaining wall 16 is constructed on the top of the north side of the south side roof 5; the soil is covered on the south side roof 5, and the existing pipeline 4 is buried at the same time; the backfilling construction process of the south side roof should be uniform and symmetrical, and should be layered and compacted, in order to protect the waterproof layer and the existing pipeline. The south side roof area is surrounded and constructed before the construction of the south side roof is completed.

[0039] S3, construction on the north side of the framed wall 8, excavate to the designated position, then remove the first steel support 9 on the south side to retain the roof retaining wall 16, erect the second steel support 10 on the north side of the roof retaining wall 16, and change the standby pipeline 3 back to the existing pipeline 4. After the standby pipeline is changed back to the existing pipeline, the traffic in the south roof area is restored.

[0040] S4, continue construction on the north side of the subway station, excavate while breaking the framed wall 8 and the standby pipeline 3, and excavate to the design elevation;

[0041] S5, construct the north roof 11 on the north side of the south roof 5 of the subway station, reserve the soil hole 12 on the north roof 11, and retain the roof retaining wall 16. When the north roof 11 reaches the specified design strength, lay the waterproof layer on the north roof 11, then cover the soil on the north roof 11, and remove the second steel support 10;

[0042] S6, excavate from the soil hole 12 to the specified elevation of the negative one floor using the top-down method, construct the negative one side wall, the negative one side wall waterproof layer, and the negative one floor 13 of the subway station. Continue to excavate to the specified elevation of the negative two floor, construct the negative two side wall, the negative one side wall waterproof layer, and the negative two floor 14 of the subway station. After the negative one floor, the negative one side wall, the negative two floor, and the negative two side wall reach 100% of the design strength, the next step of excavation construction can be performed. A temporary support beam 19 is erected between the negative two floor 14 and the steel pipe concrete column 2 for transmitting horizontal force 0 and vertical force; auxiliary support columns 18 are also provided between the negative two floor 114 and the negative one floor 13, and between the negative two floor 14 and the bottom floor 15. Auxiliary support beams 17 are also provided between the auxiliary support columns 18 and the steel pipe concrete column 2.

[0043] S7, continue to excavate to the design pit bottom elevation using the top-down method, construct the cushion layer, the bottom floor waterproof layer, and the bottom floor 15, construct the negative three side wall waterproof layer, the negative three side wall, and the negative three partition wall, i.e., the main structure construction of the station is completed.

[0044] The construction method constructs the south roof and the north roof respectively. After the construction of the south roof is completed, the traffic in the south roof area is restored. The north roof only needs to reserve the soil hole, the enclosed area is small, the construction efficiency is high, the subsequent main project is constructed using the top-down method, which can minimize the occupation of the ground. In the construction process of the south roof, the existing pipeline is connected to the standby pipeline, which can ensure the normal use of the pipeline and avoid the limitation of the existing pipeline on the construction of the south roof, and can further improve the construction efficiency.

[0045] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any slight modification, equivalent replacement, and improvement made according to the technical essence of the present application to the above embodiment shall be included in the protection scope of the technical solution of the present application.

Claims

1. A method of top-down construction over an existing pipeline, characterized by: The fender diaphragm wall is constructed around the subway station, and the steel pipe concrete column is constructed in the middle of the subway station; the standby pipeline is newly built, and then the existing pipeline is connected to the standby pipeline; the north and south side roof are excavated respectively; the existing pipeline is restored, and the soil is covered on the south side roof; the main structure is constructed by using the cover-excavation reverse construction method; The specific steps are as follows: S1, a standby pipeline is newly built on the north side of the existing pipeline; The foundation pile and the steel pipe concrete column are arranged between the fender diaphragm walls, and the split diaphragm wall is constructed on the north side of the steel pipe concrete column, which serves as the temporary fender structure for the excavation construction on the south side, and finally the dewatering is performed; S2, the existing pipeline is connected to the standby pipeline on the north side, the south side foundation pit of the split diaphragm wall is excavated to the specified position, then the first steel support is erected, and the excavation is performed to the design elevation; the south side roof of the subway station is constructed, the waterproof layer is laid on the south side roof after the south side roof reaches the design strength, and the roof retaining wall is constructed on the top of the south side roof towards the north; the soil is covered on the south side roof, and the existing pipeline is buried at the same time; S3, the construction is performed on the north side of the split diaphragm wall, the first steel support on the south side is removed after the excavation to the specified position, the top retaining wall is reserved, the second steel support is erected on the north side of the top retaining wall, and the standby pipeline is connected to the existing pipeline; S4, the construction of the north side of the subway station is continued, the split diaphragm wall and the standby pipeline are removed while excavating, and the excavation is performed to the design elevation; S5, the north side roof is constructed on the north side of the south side roof of the subway station, the soil hole is reserved on the north side roof, and the top retaining wall is reserved, the waterproof layer is laid on the north side roof after the north side roof reaches the specified design strength, then the soil is covered on the north side roof, and the second steel support is removed; S6, the cover-excavation reverse construction method is used to excavate from the soil hole to the specified elevation of the negative one floor, the negative one side wall, the waterproof layer of the negative one side wall and the negative one floor are constructed; the excavation is continued to the specified elevation of the negative two floor, the negative two side wall, the waterproof layer of the negative one side wall and the negative two floor are constructed; S7, the cover-excavation reverse construction method is continued to excavate to the design bottom elevation, the cushion layer, the waterproof layer of the bottom floor and the bottom floor are constructed, the waterproof layer of the negative three side wall, the negative three side wall and the negative three partition wall are constructed, that is, the main structure construction of the station is completed.

2. The topdown construction method over an existing pipeline according to claim 1, characterized in that: The south side roof region is surrounded and constructed before the construction of the south side roof in step S2 is completed, and the traffic of the south side roof region is restored after the existing pipeline is connected to the standby pipeline in step S3.

3. The topdown construction method over an existing pipeline according to claim 1, characterized in that The south side roof can be backfilled and covered after reaching 100% of the design strength in step S2. The negative one floor, the negative one side wall, the negative two floor and the negative two side wall can be excavated and constructed in the next step after reaching 100% of the design strength in step S6.

4. The topdown construction method over an existing pipeline according to claim 1, characterized in that The backfilling construction process of the south side roof in step S2 should be uniform and symmetrical, and should be layered and tamped, so as to protect the waterproof layer and the existing pipeline.

5. The topdown construction method over an existing pipeline according to claim 1, characterized in that The fine sand between the steel pipe concrete column and the pile hole is backfilled and compacted after the installation of the steel pipe concrete column in step S1.

6. The topdown construction method over an existing pipeline according to claim 1, characterized in that The temporary support beam is erected between the negative two floor and the steel pipe concrete column in step S6 for transmitting horizontal force and vertical force; Auxiliary support columns are arranged between the negative second floor and the negative first floor and between the negative second floor and the bottom floor. Auxiliary support beams are arranged between the auxiliary support columns and the steel pipe concrete columns.

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