Foundation pit support and construction method over deeply buried large pipeline in water-rich soft soil area

Abstract

The present invention discloses a foundation pit support and construction method for a deep-buried large pipeline in a water-rich soft soil area. Double rows of normal section foundation pit retaining piles are arranged at positions on both sides of the foundation pit corresponding to the pipeline, and multiple pipeline section foundation pit retaining piles are arranged at positions directly above the corresponding pipelines; large-diameter MJS piles that form a gravity retaining wall with the corresponding pipeline section foundation pit retaining piles are arranged outside the pipeline section foundation pit retaining piles; a row of MJS piles that are effectively overlapped with the gravity retaining wall formed by multiple large-diameter MJS piles to form a water-stop curtain are respectively driven on both sides of the pipeline. During construction, normal section foundation pit retaining piles and pipeline section foundation pit retaining piles are constructed first; after the MJS piles on both sides of the pipeline are completed to form reinforcement and water-stop curtain piles, large-diameter MJS piles are constructed to form a gravity retaining wall; finally, the crown beam and the first concrete support are constructed, and the foundation pit is excavated. The present invention avoids the relocation of deep-buried large pipelines across foundation pits in water-rich soft soil areas, and reduces the impact of foundation pit excavation on existing pipelines.

Description

Technical Field

[0001] The present invention relates to the technical field of underground engineering construction, and in particular to a foundation pit support and construction method for a deep-buried large pipeline in a water-rich soft soil area. Background Art

[0002] With the continuous development of cities, traffic congestion at intersections is becoming increasingly serious. In order to solve the traffic capacity of intersection nodes, more and more grade-separated intersections (overpasses or underpasses) are set up at intersection nodes. In order to avoid the impact of intersection overpasses on the surrounding environment, road design prefers to use underpasses to solve the problem.

[0003] Currently, there are numerous pipelines at intersections in China. With the rapid development of cities, many municipal pipelines are buried deeper and deeper. The cost of relocating many pipelines is inherently high, especially for high-voltage lines and deeply buried stormwater and sewage pipes. To avoid the impact of these pipelines on underpasses, construction methods such as open-cut overpasses or trenchless underpasses are generally used. Trenchless underpasses typically involve excavation using methods such as rectangular pipe jacking, shallow buried tunneling, and pipe curtains. These methods carry significant risks, long construction times, and high costs. Therefore, open-cut construction is preferred.

[0004] However, due to the large size of the pipeline, traditional foundation pit support measures are difficult to implement, and the soft soil area itself has poor soil stability and abundant water resources.

[0005] Therefore, how to avoid relocating existing pipelines during foundation pit excavation, take measures that cause relatively little disturbance to the pipelines, and protect the pipelines from being affected has become a technical problem that technical personnel in this field urgently need to solve. Summary of the Invention

[0006] In view of the above-mentioned defects of the prior art, the present invention provides a foundation pit support and construction method for deep-buried large pipelines in water-rich soft soil areas. The purpose is to effectively avoid the relocation of deep-buried large pipelines across foundation pits in water-rich soft soil areas. At the same time, the foundation pit support scheme can also serve as a protection measure for deep-buried large pipelines, effectively reducing the impact of foundation pit excavation on existing deep-buried underground large pipelines.

[0007] To achieve the above object, the present invention discloses a foundation pit support system for crossing a deep-buried large pipeline in a water-rich soft soil area; a plurality of normal section foundation pit retaining piles and a plurality of pipeline section foundation pit retaining piles are arranged on both sides of the foundation pit;

[0008] At the intersection of the foundation pit and the pipeline, two rows of normal section foundation pit retaining piles are arranged corresponding to the positions on both sides of the pipeline, so that the foundation pit retaining pile close to the pipeline forms an L-shaped load-bearing structure on the horizontal plane;

[0009] Directly above the pipeline, a plurality of pipeline section foundation pit retaining piles are set corresponding to positions on both sides of the foundation pit, and the depth of each of the pipeline section foundation pit retaining piles is driven to 200mm±5% directly above the pipeline, and each of the pipeline section foundation pit retaining piles is connected into one by a crown beam to form a plurality of T-beam load-bearing structures;

[0010] Two to three rows of large-diameter MJS piles are arranged along the direction of the pipeline on the outside of the plurality of pipeline section foundation pit retaining piles on both sides of the foundation pit;

[0011] The plurality of large-diameter MJS piles together with the corresponding pipeline section foundation pit retaining piles form a gravity retaining wall, and each of the large-diameter MJS piles is arranged on a support system outside the double-row normal section foundation pit retaining pile range;

[0012] At the junction of the foundation pit and the pipeline, a row of MJS piles are driven on both sides of the pipeline;

[0013] The two rows of MJS piles and the gravity retaining wall formed by the plurality of large-diameter MJS piles are effectively overlapped, so that the part of the foundation pit located above the pipeline is effectively closed to form a water-stop curtain.

[0014] Preferably, a normal section foundation pit water-stop curtain is provided on the outer sides of the normal section foundation pit retaining piles on both sides of the portion of the foundation pit that does not intersect with the pipeline.

[0015] The present invention also provides a construction method for foundation pit support over a deeply buried large pipeline in a water-rich soft soil area, comprising the following steps:

[0016] Step 1: Construction preparation;

[0017] Step 2: constructing the normal section foundation pit retaining piles and the pipeline section foundation pit retaining piles on both sides of the pipeline, and constructing the normal section foundation pit water-stop curtain;

[0018] Step 3: construct the MJS piles on both sides of the pipeline to form reinforcement and water-stopping curtain piles;

[0019] Step 4: constructing a plurality of large-diameter MJS piles outside the pipeline section foundation pit retaining piles on both sides of the foundation pit, and forming a gravity retaining wall together with the plurality of large-diameter MJS piles and the corresponding pipeline section foundation pit retaining piles;

[0020] Step 5: construct the crown beam and the first concrete support;

[0021] Step 6: excavate the foundation pit, supporting it as it is excavated, until the bottom of the foundation pit is reached;

[0022] Step 7: Build the structure to the top plate and cover it with soil to the designed elevation.

[0023] Preferably, in step 3, during construction, each of the MJS piles should be inclined at an angle of 5° to 30° relative to the vertical direction to ensure that each of the MJS piles within the bottom range of the pipeline can be effectively overlapped, and the overlap thickness is not less than 250 mm;

[0024] Preferably, in step 3, the depth of the reinforcement and water-stopping curtain piles meets the following requirements: the depth above and below the pipeline is not less than 3m, and is greater than 1 times the outer diameter of the pipeline.

[0025] Preferably, in step 5, column piles are added according to the calculated structure of the foundation pit support system.

[0026] Beneficial effects of the present invention:

[0027] The present invention relies on existing support measures and adopts comprehensive treatment measures to solve the problem of the intersection of foundation pit and pipeline in the prior art, which can avoid the relocation of existing pipelines. The relevant treatment measures all adopt measures that cause relatively little disturbance to the pipelines, and can also play a role in protecting the pipelines during the foundation pit excavation process.

[0028] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The figure shows the plan layout of pipelines and foundation pits in one embodiment of the present invention.

[0030] Figure 2 A cross-sectional view showing a portion of a foundation pit that does not intersect with a pipeline in one embodiment of the present invention.

[0031] Figure 3 A cross-sectional view of the intersection of a foundation pit and a pipeline in one embodiment of the present invention is shown.

[0032] Figure 4 Shown are elevation views of the retaining piles for the normal section of the pipeline and the retaining piles for the pipeline section on both sides of the pipeline in one embodiment of the present invention.

[0033] Figure 5 A vertical view of a gravity retaining wall at the intersection of a foundation pit and pipelines in one embodiment of the present invention is shown. DETAILED DESCRIPTION

[0034] Example

[0035] like Figures 1 to 4 As shown, the foundation pit support is provided on the deep buried large pipeline in the water-rich soft soil area; multiple normal section foundation pit retaining piles 1 and multiple pipeline section foundation pit retaining piles 2 are provided on both sides of the foundation pit;

[0036] At the intersection of the foundation pit and the pipeline, two rows of normal section foundation pit retaining piles 1 are set at the positions corresponding to both sides of the pipeline, so that the foundation pit retaining piles close to the pipeline form an L-shaped load-bearing structure on the horizontal plane;

[0037] Directly above the pipeline, multiple pipeline segment foundation pit retaining piles 2 are set at the corresponding positions on both sides of the foundation pit, and the depth is driven to 200mm±5% directly above the pipeline. Each pipeline segment foundation pit retaining pile 2 is connected into one by a crown beam 6 to form a multiple T-beam load-bearing structure;

[0038] On the outside of the multiple pipeline section foundation pit retaining piles 2 on both sides of the foundation pit, there are 2 to 3 rows of large-diameter MJS piles 4 set along the direction of the pipelines;

[0039] Multiple large-diameter MJS piles 4 form a gravity retaining wall together with the corresponding pipeline section foundation pit retaining piles 2, and each large-diameter MJS pile 4 is set on the support system within the range of the non-double-row normal section foundation pit retaining piles 1;

[0040] At the junction of the foundation pit and the pipeline, a row of MJS piles 3 are driven on both sides of the pipeline;

[0041] The gravity retaining wall formed by two rows of MJS piles 3 and multiple large-diameter MJS piles 4 is effectively overlapped, so that the part of the foundation pit above the pipeline is effectively closed to form a water-stop curtain.

[0042] A multi-point support system is formed by using piles and supports on both sides of the pipeline, and is reinforced with a water-stop curtain and gravity retaining wall support system in the middle area to form effective support for the pipeline area.

[0043] In some embodiments, normal section foundation pit water-stop curtains 5 are provided on the outer sides of the normal section foundation pit retaining piles 1 on both sides of the portion where the foundation pit does not intersect with the pipeline.

[0044] The present invention also provides a construction method for foundation pit support over a deeply buried large pipeline in a water-rich soft soil area, comprising the following steps:

[0045] Step 1: Construction preparation;

[0046] Step 2: construct the normal section foundation pit retaining piles 1 and the pipeline section foundation pit retaining piles 2 on both sides of the pipeline, and construct the normal section foundation pit water-stop curtain 5;

[0047] Step 3: construct MJS piles 3 on both sides of the pipeline to form reinforcement and water-stop curtain piles;

[0048] Step 4: construct large-diameter MJS piles 4 outside the multiple pipeline segment foundation pit retaining piles 2 on both sides of the foundation pit, and form a gravity retaining wall together with the multiple large-diameter MJS piles 4 and the corresponding pipeline segment foundation pit retaining piles 2;

[0049] Step 5: construct the crown beam 6 and the first concrete support 7;

[0050] Step 6: Excavate the foundation pit and support it as you go until you reach the bottom of the foundation pit;

[0051] Step 7: Build the structure to the top plate and cover it with soil to the designed elevation.

[0052] Preferably, in step 3, during construction, each MJS pile 3 should be inclined at an angle of 5° to 30° relative to the vertical direction to ensure that each MJS pile 3 within the bottom range of the pipeline can be effectively overlapped, and the overlap thickness is not less than 250 mm;

[0053] like Figure 5 As shown, in certain embodiments, in step 3, the depth of the reinforcement and water-stopping curtain piles meets the following requirements: the depth above and below the pipeline is not less than 3m, and is greater than 1 times the outer diameter of the pipeline.

[0054] In some embodiments, in step 5, column piles 8 are added according to the calculated structure of the foundation pit support system.

[0055] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A construction method for foundation pit support over a deep buried large pipeline in a water-rich soft soil area; it is characterized by: A plurality of normal section foundation pit retaining piles (1) and a plurality of pipeline section foundation pit retaining piles (2) are arranged on both sides of the foundation pit; At the intersection of the foundation pit and the pipeline, two rows of normal section foundation pit retaining piles (1) are arranged corresponding to the positions on both sides of the pipeline, so that the foundation pit retaining piles close to the pipeline form an L-shaped force-bearing structure on the horizontal plane; Directly above the pipeline, a plurality of pipeline section foundation pit retaining piles (2) are arranged corresponding to positions on both sides of the foundation pit, and the depth of each of the pipeline section foundation pit retaining piles (2) is driven to 200 mm ± 5% directly above the pipeline, and each of the pipeline section foundation pit retaining piles (2) is connected into one piece by a crown beam (6), forming a plurality of T-beam force-bearing structures; Two to three rows of large-diameter MJS piles (4) are arranged along the direction of the pipeline on the outside of the plurality of pipeline section foundation pit retaining piles (2) on both sides of the foundation pit; The plurality of large-diameter MJS piles (4) together with the corresponding pipeline section foundation pit retaining piles (2) form a gravity retaining wall, and each of the large-diameter MJS piles (4) is arranged on a support system that is not within the range of the double-row normal section foundation pit retaining piles (1); At the junction of the foundation pit and the pipeline, a row of MJS piles (3) are driven on both sides of the pipeline; The two rows of MJS piles (3) and the gravity retaining wall formed by the plurality of MJS piles (4) with a large diameter are effectively overlapped, so that the part of the foundation pit located above the pipeline is effectively closed to form a water-stop curtain; A normal section foundation pit water-stop curtain (5) is provided on the outer sides of the normal section foundation pit retaining piles (1) on both sides of the part of the foundation pit that does not intersect with the pipeline; The steps include: Step 1: Construction preparation; Step 2, constructing the normal section foundation pit retaining piles (1) and the pipeline section foundation pit retaining piles (2) on both sides of the pipeline, and constructing the normal section foundation pit water-stopping curtain (5); Step 3, constructing the MJS piles (3) on both sides of the pipeline to form reinforcement and water-stopping curtain piles; During construction, each of the MJS piles (3) should be inclined at an angle of 5° to 30° relative to the vertical direction to ensure that each of the MJS piles (3) within the bottom range of the pipeline can be effectively overlapped, and the overlap thickness is not less than 250 mm; The depth of the reinforcement and water-stopping curtain piles meets the following requirements: the depth above and below the pipeline is not less than 3m, and greater than 1 times the outer diameter of the pipeline; Step 4, constructing a plurality of large-diameter MJS piles (4) outside the pipeline section foundation pit retaining piles (2) on both sides of the foundation pit, and forming a gravity retaining wall together with the plurality of large-diameter MJS piles (4) and the corresponding pipeline section foundation pit retaining piles (2); Step 5: construct the crown beam (6) and the first concrete support (7); Step 6, excavating the foundation pit, supporting it as it is excavated, until the bottom of the foundation pit is excavated; Step 7: Build the structure to the top plate and cover it with soil to the designed elevation.

2. The construction method for foundation pit support over a deep buried large pipeline in a water-rich soft soil area according to claim 1 is characterized in that: In step 5, column piles (8) are added according to the calculated structure of the foundation pit support system.

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