Secant pile wall type foundation pit supporting structure crossing large underground pipeline

Abstract

The utility model discloses a secant pile wall type spanning large underground pipeline foundation pit supporting structure which is mainly composed of a front-row secant pile wall, a rear-row secant pile wall and a plain secant pile web wall, and the front-row secant pile wall and the rear-row secant pile wall are connected through the plain secant pile web wall, a connecting beam of the plain secant pile web wall and an inter-beam plate. The front-row secant pile wall is formed by connecting plain concrete piles and reinforced concrete piles which are arranged at intervals and meshed with each other through a front crown beam, and the rear-row secant pile wall is formed by connecting plain concrete piles and reinforced concrete piles which are arranged at intervals and meshed with each other through a rear crown beam; a notch is reserved in the front-row secant pile wall at the position of the shallow-buried large underground pipeline under the foundation pit, and the rear-row secant pile wall is disconnected at the position of the shallow-buried large underground pipeline under the foundation pit. The foundation pit supporting structure has the advantages of being large in lateral rigidity, high in bending resistance and shearing resistance and the like, has the soil blocking and water stopping functions, and can solve the supporting problem that the foundation pit supporting structure at the position of the underlying large underground pipeline of the deep foundation pit bottom of an urban foundation pit crosses the large underground pipeline.

Description

Technical Field

[0001] The utility model belongs to the technical field of foundation pit support structures in geotechnical engineering, in particular to an interlocking pile-wall type foundation pit support structure spanning a large underground pipeline. Background Art

[0002] Deep foundation pits for newly constructed structures in urban renewal projects in older urban areas often require foundation pit support. With technological advancements, interlocking pile wall retaining structures, a more economical and water-retaining support structure than underground continuous walls, have become increasingly popular in foundation pit support projects. However, when large underground pipelines are buried close to the bottom of a deep foundation pit, the underground space above these pipelines is often not fully utilized due to the difficulty of foundation pit support, resulting in a waste of urban underground space resources.

[0003] In order to solve the problem of foundation pit support at large underground pipelines, the Chinese patent "Support Structure for Foundation Pit Across Large Underground Pipelines" (patent number 202020950941.2, announcement date June 18, 2021) adopts a spatial rigid frame structure formed by connecting front piles, rear piles and reverse retaining plates and their crown beams and connecting beams to bear the horizontal earth pressure of the missing sections of the retaining piles at the underground pipelines under the foundation pit, and has achieved good results. However, this support structure has only crown beams and connecting beams connecting the piles, and its stiffness is relatively low. It only has a retaining effect and does not have a water-stopping function, and its application scenarios are limited. For example, it is not suitable for deep foundation pit support in soft soil strata or sandy soil strata rich in groundwater, and it cannot solve the problem of deep foundation pit support with water-stopping needs. Furthermore, due to its relatively low stiffness, it is difficult to meet the foundation pit support requirements of ultra-large underground pipelines such as subway tunnels under the foundation pit. In addition, cast-in-place piles are constructed using rotary drilling rigs or long spiral drills, which cause relatively large construction vibrations and disturbances, and are prone to cause collapse in soft soil or sandy soil strata. This may cause accidents such as excessive deformation and cracking of super-large underground pipelines such as prefabricated and assembled subway shield tunnel structures. Summary of the Invention

[0004] The technical problem to be solved by the utility model is to provide a occlusal pile wall type foundation pit support structure spanning a large underground pipeline which has greater rigidity and has both soil retaining and water stopping functions.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] The interlocking pile wall type foundation pit support structure spanning a large underground pipeline is mainly composed of a front-row interlocking pile wall, a rear-row interlocking pile wall and a plain interlocking pile web wall. The front-row interlocking pile wall and the rear-row interlocking pile wall are connected by the plain interlocking pile web wall, its connecting beam and the beam inter-plate; the front-row interlocking pile wall is composed of plain concrete piles and reinforced concrete piles arranged at intervals and interlocked with each other and connected by a front crown beam; the rear-row interlocking pile wall is composed of plain concrete piles and reinforced concrete piles arranged at intervals and interlocked with each other and connected by a rear crown beam; a gap is reserved in the front-row interlocking pile wall at the shallow-buried large underground pipeline under the foundation pit, and the rear-row interlocking pile wall is disconnected at the shallow-buried large underground pipeline under the foundation pit.

[0007] The plain interlocking pile web wall is composed of multiple plain concrete interlocking piles interlocking with each other. The plain concrete interlocking piles on the front and rear sides of the plain interlocking pile web wall are interlocked and connected with the plain concrete piles of the front row interlocking pile wall and the rear row interlocking pile wall respectively.

[0008] The front crown beam is located at the top of the front row of interlocking pile wall; the rear crown beam is located at the top of the rear row of interlocking pile wall; and the connecting beam is located at the top of the web wall of the plain interlocking pile.

[0009] The front crown beam, rear crown beam, connecting beam and the plates between beams are located at the same elevation and are interconnected to form a whole.

[0010] The bottom of the interlocking pile wall at the notch in the front row of interlocking pile wall is embedded in the soil at the bottom of the foundation pit and the net distance between it and the large underground pipeline is not less than 0.3m. The net distance between the large underground pipeline and the interlocking pile wall at the notch on both sides is not less than 0.3m; the net distance between the large underground pipeline and the interlocking pile wall on both sides at the break in the rear row of interlocking pile wall is not less than 0.3m.

[0011] In view of the problems that the existing foundation pit support structure crossing large underground pipelines has low rigidity, only has soil retaining function but no water-stopping function, and has large construction vibration and disturbance, is difficult to be used for super-large underground pipelines such as subway tunnels under the foundation pit, and is not suitable for foundation pit support that requires water stopping, the inventor has designed a bite pile wall type foundation pit support structure crossing large underground pipelines, which is mainly composed of a front-row bite pile wall, a rear-row bite pile wall and a plain bite pile web wall. The front-row bite pile wall and the rear-row bite pile wall are connected by the plain bite pile web wall and its connecting beam and beam interplate; the front-row bite pile wall is composed of plain concrete piles and reinforced concrete piles arranged at intervals and interlocked with each other and connected by a front crown beam, and the rear-row bite pile wall is composed of plain concrete piles and reinforced concrete piles arranged at intervals and interlocked with each other and connected by a rear crown beam; the front-row bite pile wall has a gap reserved at the shallow-buried large underground pipeline under the foundation pit, and the rear-row bite pile wall is disconnected at the shallow-buried large underground pipeline under the foundation pit.

[0012] Compared with the prior art, the outstanding advantages of the present invention are:

[0013] (1) The support structure of the present invention reserves a gap at the underground pipeline through the front-row interlocking pile wall, thereby avoiding the need to construct a reverse retaining wall above the underground pipeline with low construction efficiency in the prior art. It has the functions of retaining soil and stopping water, and has the characteristics of greater lateral stiffness, stronger bending and shearing resistance, etc. It has stronger and wider applicability, solves the problem of foundation pit support that requires water stopping, and solves the problem of foundation pit support at super-large underground pipelines such as shallow buried subway tunnels under the foundation pit.

[0014] (2) The interlocking pile wall in the support structure of the present invention is constructed using a full-casing and full-rotation construction process. The drilling and cutting of the interlocking piles are both performed by rotating the casing to cut the soil to form holes and also serve as casing. The construction vibration and disturbance are small, and there will be no hole collapse causing loss of stratum and causing excessive deformation or cracking of the adjacent underground pipeline structure. This solves the problem of engineering accidents caused by the support of shallow buried large underground pipelines under deep urban foundation pits in sensitive strata such as soft soil foundations and water-rich sandy soil foundations, and enables the full utilization of urban underground space resources above super-large underground pipelines. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The utility model is a schematic plan view of a foundation pit support structure of a large underground pipeline spanned by an interlocking pile wall.

[0016] Figure 2 The utility model is a schematic elevation diagram of a foundation pit support structure for spanning a large underground pipeline using an interlocking pile wall type.

[0017] Figure 3 The utility model is a cross-sectional schematic diagram of a foundation pit support structure for spanning a large underground pipeline using an interlocking pile wall type.

[0018] In the figure: 1 front row interlocking pile wall, 1ai (i = 1, 2, 3, ...) plain concrete piles of the front row interlocking pile wall, 1bi (i = 1, 2, 3, ...) reinforced concrete piles of the front row interlocking pile wall, 2 rear row interlocking pile wall, 2ai (i = 1, 2, 3, ...) plain concrete piles of the rear row interlocking pile wall, 21bi (i = 1, 2, 3, ...) reinforced concrete piles of the rear row interlocking pile wall, 3 plain interlocking pile web wall, 4 front crown beam, 5 rear crown beam, 6 connecting beam, 7 beam spacer, 8 large underground pipeline, H1 ground elevation, H2 foundation pit bottom elevation, H3 elevation of the bottom of the interlocking pile wall at the notch of the front row interlocking pile wall. DETAILED DESCRIPTION

[0019] 1. Basic structure

[0020] like Figures 1 to 3As shown in the figure, the present invention's interlocking pile wall type foundation pit support structure for spanning large underground pipelines is mainly composed of a front row interlocking pile wall 1, a rear row interlocking pile wall 2, and a plain interlocking pile web wall 3. The front row interlocking pile wall and the rear row interlocking pile wall are connected by the plain interlocking pile web wall and its connecting beam 6 and the beam inter-plate 7 to form a retaining and water-stopping structure with huge lateral stiffness.

[0021] The front-row interlocking pile wall is composed of plain concrete piles and reinforced concrete piles arranged at intervals and interlocked with each other and connected by a front crown beam 4, serving as a continuous underground interlocking pile wall foundation pit support retaining and water-stopping enclosure structure; the rear-row interlocking pile wall is composed of plain concrete piles and reinforced concrete piles arranged at intervals and interlocked with each other and connected by a rear crown beam 5, serving as a continuous underground interlocking pile wall component; the front-row interlocking pile wall reserves a gap at the shallow-buried large underground pipeline under the foundation pit to meet the passage of the large underground pipeline, and the rear-row interlocking pile wall is disconnected at the shallow-buried large underground pipeline under the foundation pit.

[0022] The plain interlocking pile web wall is composed of multiple plain concrete interlocking piles that are interlocked with each other. The plain concrete interlocking piles on the front and back sides of the plain interlocking pile web wall are respectively interlocked and connected with the plain concrete piles of the front row interlocking pile wall and the rear row interlocking pile wall, so that two I-shaped underground continuous pile walls are formed on both sides of the large underground pipeline and connected side by side.

[0023] The front crown beam is located at the top of the front row of interlocking pile walls, further strengthening the connection between them. The rear crown beam is located at the top of the rear row of interlocking pile walls, further strengthening the connection between them. The coupling beam is located at the top of the plain interlocking pile web walls, further strengthening the connection between them. The front crown beam, rear crown beam, coupling beam, and their inter-beam plates are located at the same elevation and connected to form a single unit.

[0024] 2. Construction method

[0025] <1> Construction of the front and rear interlocking pile walls: After the site is leveled, a full-casing, full-rotation drill is used to sequentially rotate and cut the rock and soil to form holes and cast 1ai (i=1, 2, 3, ...) plain concrete piles for the front interlocking pile wall. Then, 1bi (i=1, 2, 3, ...) reinforced concrete piles for the front interlocking pile wall are sequentially constructed. A gap is reserved for the large underground pipeline beneath the foundation pit in the front interlocking pile wall to allow the large underground pipeline 8 to pass through (the distance between the two sides of the gap and the underground pipeline structure is no less than 0.3m, and the distance between the bottom of the interlocking pile wall at the gap and the underground pipeline is no less than 0.3m). Similarly, the rear interlocking pile walls are constructed on both sides of the underground pipeline using the same method (the net distance between the large underground pipeline and the interlocking pile wall at the disconnection point is no less than 0.3m).

[0026] <2> Construction of front crown beam, rear crown beam, connecting beam and inter-beam slab: excavate the soil and remove the over-concrete of the front row piles and rear piles to the designed pile top elevation, and make the cast-in-place pile reinforcement cage expose 35 times the diameter of the reinforcement and anchor it into the crown beam and connecting beam at the top of each pile. Use the foundation as the ground formwork to tie the crown beam, cross beam and inter-beam slab reinforcement, set up the side formwork of the crown beam and cross beam, pour concrete and maintain it to the designed strength, so that the front row piles and rear piles are fixed to form a spatial rigid frame structure and then excavation of the foundation pit can be carried out.

Claims

1. A occlusal pile wall type foundation pit support structure spanning a large underground pipeline, characterized by It is mainly composed of a front-row interlocking pile wall, a rear-row interlocking pile wall and a plain interlocking pile web wall. The front-row interlocking pile wall and the rear-row interlocking pile wall are connected by the plain interlocking pile web wall, its connecting beam and the beam interplate; the front-row interlocking pile wall is composed of plain concrete piles and reinforced concrete piles arranged at intervals and interlocked with each other and connected by a front crown beam, and the rear-row interlocking pile wall is composed of plain concrete piles and reinforced concrete piles arranged at intervals and interlocked with each other and connected by a rear crown beam; the front-row interlocking pile wall is provided with a gap at the shallow-buried large underground pipeline under the foundation pit, and the rear-row interlocking pile wall is disconnected at the shallow-buried large underground pipeline under the foundation pit.

2. The foundation pit supporting structure according to claim 1, characterized in that: The plain interlocking pile web wall is composed of multiple plain concrete interlocking piles interlocking with each other. The plain concrete interlocking piles on the front and rear sides of the plain interlocking pile web wall are respectively interlocked and connected with the plain concrete piles of the front row interlocking pile wall and the rear row interlocking pile wall.

3. The foundation pit supporting structure according to claim 1, characterized in that: The front crown beam is located at the top of the front row of interlocking pile walls; the rear crown beam is located at the top of the rear row of interlocking pile walls; and the connecting beam is located at the top of the web wall of the plain interlocking piles.

4. The foundation pit supporting structure according to claim 3, characterized in that: The front crown beam, rear crown beam, connecting beam and the inter-beam plates thereof are located at the same elevation and are interconnected to form a whole.

5. The foundation pit supporting structure according to claim 4, characterized in that: The bottom of the interlocking pile wall at the notch in the front row of interlocking pile wall is embedded in the soil at the bottom of the foundation pit and has a net distance of not less than 0.3m from the large underground pipelines thereunder, and the net distance between the large underground pipelines on both sides and the interlocking pile wall at the notch is not less than 0.3m; the net distance between the large underground pipelines on both sides and the interlocking pile wall at the disconnection point in the rear row of interlocking pile wall is not less than 0.3m.

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