Excavation supporting structure for water inlet and hole face located on soft foundation

Abstract

The utility model provides an excavation supporting structure for a water inlet and a hole face sitting on a soft foundation, a gentle slope is pre-excavated at the upper part of a water inlet pre-excavation area at the position of a dam foot reservoir bottom, a row pile structure is vertically and downwards arranged on a platform formed at the bottom of the gentle slope, and the row pile structure is arranged on two sides of the pre-excavated water inlet. A pile foundation is arranged in the pile-in-row structure in a driving mode, a tunnel face retaining wall is vertically and downwards arranged in a tunnel face pre-excavation area of the platform, the tunnel face retaining wall is divided into an upper structure and a lower structure which are connected with each other in the vertical direction, and an inclined supporting pier fixedly connected with the pile-in-row structure is arranged on the side edge of the upper structure of the tunnel face retaining wall. For the soil foundation pit which cannot be excavated in a large area, the pile foundation and the hole face retaining wall need to be used for excavating the water inlet and the hole face, gentle slope excavation is replaced by the pile foundation, the pile foundation is supported by the soil anchor cable, soil pressure on the left side and the right side of the foundation pit is transmitted to the pile foundation, and finally stress is jointly borne by the embedded part of the pile foundation and the soil anchor cable.

Description

Technical Field

[0001] The utility model relates to the technical field of excavation and support engineering of hydraulic structures, in particular to an excavation and support structure of a water inlet and a hole face sitting on a soft foundation. Background Art

[0002] When excavating foundation pits for hydraulic structures located on soft foundations, the usual practice is to use the method of slowing down the slope during excavation, spraying concrete on the soil slope and adding drainage holes, and sometimes it is necessary to set up frame beams to stabilize the slope. The obvious disadvantage of this method is that the opening line is too large, which will lead to excessive excavation in cases where the terrain is complex. This method is not suitable for areas with complex terrain and areas where the excavation range itself is limited. For example, when the land acquisition range is limited or the excavation of the reservoir bottom affects the foundation of the dam, other options need to be considered. For the water inlet of a hydraulic structure, if it is located on a soft foundation, it is necessary to consider the excavation of the water inlet itself and the excavation of the hole face, which will lead to a problem: how to ensure that the water inlet and the hole face are vertically excavated while ensuring safety. Therefore, it is necessary to design the excavation support structure of the water inlet and the hole face located on the soft foundation to solve the above practical engineering problems. Utility Model Content

[0003] The purpose of the utility model is to provide an excavation support structure that can vertically excavate the water inlet and the hole face on the soft foundation, and has high safety and reasonable force. To this end, the utility model adopts the following technical solutions:

[0004] The excavation support structure of the water inlet and the tunnel face sitting on the soft foundation is pre-excavated with a gentle slope on the upper part of the pre-excavated area of ​​the water inlet at the bottom of the dam foot reservoir, and a pile structure is vertically arranged downward on the platform formed at the bottom of the gentle slope. The pile structure is arranged on both sides of the pre-excavated water inlet, and pile foundations are driven inside the pile structure. The bottom elevation of the pile foundation is lower than the bottom elevation of the bottom plate of the water inlet. The platform is vertically arranged with a tunnel face retaining wall in the pre-excavated area of ​​the tunnel face. The tunnel face retaining wall is divided into an upper structure and a lower structure connected to each other in the vertical direction, and an inclined support pier fixedly connected to the pile structure is arranged on the side of the upper structure of the tunnel face retaining wall.

[0005] Furthermore: a cap beam is commonly arranged on the top of the pile foundations in the same direction of the water inlet flow direction to integrally connect the pile foundations on the same side and to connect them with the oblique supporting piers.

[0006] Furthermore: a sprayed concrete layer is arranged between the pile foundations in the same direction as the flow direction of the water inlet, and the sprayed concrete layer covers the soil between the pile foundations.

[0007] Furthermore: a soil anchor cable is arranged in the pile row structure, one end of the soil anchor cable is fixed on the pile foundation, and the other end extends into the soil.

[0008] Furthermore: drainage holes are provided between the cast-in-place piles in the sprayed concrete layer obliquely upward.

[0009] Furthermore: a steel arch frame is preset in the upper structure of the tunnel face retaining wall, and the elevation of the bottom of the steel arch frame is higher than or equal to the elevation of the tunnel axis of the tunnel.

[0010] Furthermore: a pipe rack is set in the end surface of the tunnel face retaining wall obliquely upward toward the inside of the tunnel, and the axis of the pipe rack is inclined toward the side away from the tunnel relative to the axial direction of the tunnel.

[0011] Furthermore: a drainage hole of the gentle slope section extending into the soil body is provided in the gentle slope.

[0012] Compared with the prior art, the utility model has the following beneficial effects:

[0013] The utility model is aimed at soil foundation pits that cannot be excavated on a large scale. It is necessary to use pile foundations and hole face retaining walls to excavate the water inlet and hole face. By using pile foundations to replace gentle slope excavation, the pile foundations are supported by soil anchor cables, and the soil pressure on the left and right sides of the foundation pit is transmitted to the pile foundations. The final force is borne by the buried part of the pile foundation and the soil anchor cables. Therefore, the impact range of large-scale excavation can be reduced, and the problem of soil foundations that cannot be excavated on a large scale is solved. At the same time, when the water inlet pile foundation and the hole face retaining wall are combined, the vertical excavation problem of the water inlet and the hole face is systematically solved, avoiding the unfavorable factors of slowing down the slope of the soil foundation pit, and ensuring construction safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is the plan view of the water inlet excavation of the utility model;

[0015] Figure 2 It is a longitudinal section view of the water inlet and tunnel of the utility model;

[0016] Figure 3 For this utility model Figure 2 Cross-sectional view of the water inlet at AA;

[0017] Figure 4 For this utility model Figure 3 Pile foundation section diagram of middle BB;

[0018] Figure 5 This is a front view of the hole face of the utility model;

[0019] Figure 6 For this utility model Figure 5 Cross-section of CC.

[0020] The markings in the attached figure are: 1-pile foundation; 2-cap beam; 3-gentle slope; 4-dam foot; 5-hole face retaining wall; 6-tunnel; 7-soil anchor cable; 8-drainage hole in gentle slope section; 9-prism monitoring; 10-drainage hole between cast-in-place piles; 11-oblique support pier; 12-sprayed concrete layer; 13-fiberglass anchor rod; 14-pipe shed; 15-advance drainage hole; 16-platform; 17-steel arch frame. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0022] like Figure 1-6 As shown, the excavation support structure of the water inlet and the tunnel face sitting on the soft foundation, a gentle slope 3 is pre-excavated on the upper part of the water inlet pre-excavation area within the reservoir bottom range of the dam foot 4, and the opening line is determined on the principle of not affecting the top dam foot 4 or avoiding large-scale excavation. The gentle slope section is supported by sprayed concrete, and a pile structure is vertically arranged downward on the platform 16 formed at the bottom of the gentle slope 3. The pile structure is arranged on both sides of the pre-excavated foundation pit, and a pile foundation 1 is driven into the pile structure. The bottom elevation of the pile foundation 1 is lower than the bottom elevation of the water inlet bottom plate, so that the water inlet side wall is supported by the vertical pile foundation 1, and the soil pressure on the left and right sides of the foundation pit can be transmitted to the pile foundation 1. The platform 16 is vertically arranged downward in the tunnel face pre-excavation area of ​​the tunnel 6. The tunnel face retaining wall 5 is divided into an upper structure and a lower structure in the vertical direction, and the boundary line between the upper structure and the lower structure is divided by the elevation of the tunnel axis of the tunnel 6 (such as Figure 5 As shown in the figure, the upper structure and the lower structure are cast in sequence so that the lower structure is connected with the upper structure to form the overall tunnel face retaining wall 5. The tunnel face, except for the heading face, is supported by the tunnel face retaining wall 5 of the concrete wall. The side of the upper structure of the tunnel face retaining wall 5 is provided with an inclined support pier 11 fixedly connected to the pile structure.

[0023] like Figure 1-3 As shown in Figures 3-6, in this embodiment, a crown beam 2 is commonly arranged on the top of the pile foundation 1 in the same direction of the water inlet flow direction. The crown beam 2 adopts a concrete crown beam without a seam to strengthen the connection of the pile foundation 1; the internal steel bars of the crown beam 2 are connected to the steel bars on the top of the pile foundation 1, so as to fix the pile foundation 1 on the same side as a whole through the crown beam 2, and to connect the pile foundation 1 with the oblique support pier 11 through the crown beam 2, so that the oblique support piers 11 on the left and right sides of the hole face retaining wall 5 sit on the crown beam 2 of the pile foundation 1.

[0024] like Figure 4As shown, in this embodiment, a sprayed concrete layer 12 is arranged between the pile foundations 1 in the same direction as the flow direction of the water inlet, and the sprayed concrete layer 12 covers the soil between the pile foundations 1, so that the gaps between the pile foundations 1 are supported by sprayed concrete, and the soil between the pile foundations 1 is separated from the water inlet. The overall sprayed concrete layer 12 is arranged in layers from top to bottom during casting. Among them, the drainage holes 10 between the cast-in-place piles are opened obliquely upward in the sprayed concrete layer 12, and the drainage holes 10 between the cast-in-place piles extend obliquely into the soil between the piles.

[0025] like Figure 3 As shown, in this embodiment, soil anchor cables 7 are arranged in the pile row structure. The soil anchor cables 7 are also arranged in layers. One end of the soil anchor cable 7 is fixed to the pile body of the pile foundation 1, and the other end extends into the soil. The anchoring force between the soil anchor cable 7 and the soil provides stable support for the pile foundation 1.

[0026] like Figure 5 As shown, in this embodiment, a steel arch frame 17 is preset in the upper structure of the tunnel face retaining wall 5, and the bottom elevation of the steel arch frame 17 is above the tunnel axis elevation of the tunnel 6.

[0027] like Figure 2 As shown, in this embodiment, a pipe shed 14 is obliquely set in the end face of the tunnel face retaining wall 5 toward the inside of the tunnel 6, and the axis of the pipe shed 14 is inclined toward the side away from the tunnel 6 relative to the axial direction of the tunnel 6. In addition, the pipe shed 14 at the top of the tunnel face 6 is set on the upper half of the outer periphery of the tunnel 6 working face, obliquely outward at a certain angle, and all the pipe sheds 14 are arranged in a fan shape as a whole.

[0028] like Figure 3 As shown, in this embodiment, a gentle slope section drainage hole 8 extending into the soil is provided in the gentle slope 3.

[0029] like Figure 2 As shown, a prism monitoring system is also provided on the top of the crown beam 2, and the deformation of the pile foundation 1 is analyzed by monitoring the prism 9 to ensure safety.

[0030] like Figure 5 As shown, the tunnel 6 heading face is excavated vertically from top to bottom in layers, and glass fiber anchors 13 are immediately driven after excavation to support the heading face.

[0031] See also Figure 1-6 When constructing the excavation support structure on the soft foundation, the specific construction is as follows:

[0032] S1: excavate the gentle slope 3 in the upper part in advance and set drainage holes 8 in the gentle slope section. Determine the opening line in principle without affecting the top dam foundation or avoiding large-scale excavation. Excavate from top to bottom. The water inlet slope adopts the type of upper gentle slope excavation and lower vertical excavation to minimize the depth of the pile foundation 1 and reduce the difficulty of constructing the pile foundation 1.

[0033] S2: spray concrete support on the gentle slope 3. After the excavation and support of the upper gentle slope 3 is completed, pile foundations 1 are set on the lower platform 16. The length and spacing of the pile foundations 1 are determined according to the retaining pressure, and the soil squeezing effect is considered so that the pile foundations 1 are not too thin and the soil is squeezed out;

[0034] S3: Complete the pouring of the crown beam 2 on the top of the pile foundation 1, and ensure that the steel bars on the top of the pile foundation 1 are connected with the steel bars of the crown beam 2 to strengthen the integrity of the pile foundation 1 and the crown beam 2;

[0035] S4: vertical local trenching is performed at the tunnel face position to form the installation range of the steel arch frame 17. The trenching is only dug to the elevation of the tunnel axis. After the steel bars are erected, the upper structure of the tunnel face retaining wall 5 and the oblique support pier 11 are cast. The steel casing of the pipe shed 14 is pre-buried in the tunnel face retaining wall 5;

[0036] S5: After the concrete structure strength of the tunnel face retaining wall 5 meets the requirements, the pre-buried steel casing in the tunnel face retaining wall 5 is used to drive the pipe shed 14 at a small angle toward the tunnel direction;

[0037] S6: vertical excavation of the foundation pit is performed in layers, and monitoring prisms 9 are pre-set on the side of the crown beam 2 as a monitoring means for monitoring. When the excavation reaches the anchor cable position of each layer, soil anchor cables 7 are installed, and the soil between the piles of the pile foundation 1 is sprayed with mesh concrete to form a sprayed concrete layer 12. At the same time, drainage holes 10 between the cast-in-place piles are installed obliquely upward. After completion, the excavation of the next layer of the foundation pit is continued until the bottom plate of the water inlet is dug;

[0038] S7: Excavate vertically layer by layer in the tunnel face area, drive glass fiber anchor rods 13 after each layer is excavated, and at the same time, drive advance drainage holes 15 of the tunnel section, excavate layer by layer until the bottom plate elevation is reached;

[0039] S8: Complete the trench excavation of the lower structure of the tunnel face retaining wall 5, erect steel bars and cast the lower structure reinforced concrete side walls and bottom plate of the tunnel face retaining wall 5 (below the tunnel axis elevation), and thus complete the vertical excavation of the entire water inlet side wall and the vertical excavation support of the tunnel face and heading.

[0040] The above embodiment is only a preferred technical solution of the present invention. Those skilled in the art should understand that the technical solutions or parameters in the embodiments can be modified or replaced without departing from the principle and essence of the present invention, and all should be included in the protection scope of the present invention.

Claims

1. The excavation support structure of the water inlet and the hole face sitting on the soft foundation is characterized by: A gentle slope (3) is pre-excavated above the pre-excavated area of ​​the water inlet at the bottom of the reservoir at the foot of the dam (4), and a pile row structure is vertically arranged on a platform (16) formed at the bottom of the gentle slope (3). The pile row structure is arranged on both sides of the pre-excavated water inlet, and a pile foundation (1) is driven into the pile row structure. A tunnel face retaining wall (5) is vertically arranged in the pre-excavated area of ​​the tunnel face (6) on the platform (16). The tunnel face retaining wall (5) is divided into an upper structure and a lower structure connected to each other in the vertical direction, and an oblique support pier (11) fixedly connected to the pile row structure is arranged on the side of the upper structure of the tunnel face retaining wall (5).

2. The excavation support structure of the water inlet and the hole face sitting on the soft foundation according to claim 1 is characterized in that: A cap beam (2) is commonly arranged on the top of the pile foundations (1) in the same direction of the water inlet flow direction to integrally connect the pile foundations (1) on the same side and to connect them to the oblique support pier (11).

3. The excavation support structure of the water inlet and the hole face sitting on the soft foundation according to claim 1 is characterized in that: A sprayed concrete layer (12) is provided between the pile foundations (1) in the same direction as the water inlet flow direction, and the sprayed concrete layer (12) covers the soil between the pile foundations (1).

4. The excavation support structure of the water inlet and the hole face sitting on the soft foundation according to claim 1 is characterized in that: A soil anchor cable (7) is arranged in the pile row structure, one end of the soil anchor cable (7) is fixed on the pile foundation (1), and the other end extends into the soil.

5. The excavation support structure of the water inlet and the hole face sitting on the soft foundation according to claim 3 is characterized in that: Drainage holes (10) between the cast-in-place piles are provided in the sprayed concrete layer (12) obliquely upward.

6. The excavation support structure of the water inlet and the hole face sitting on the soft foundation according to claim 1 is characterized in that: A steel arch frame (17) is preset in the upper structure of the tunnel face retaining wall (5), and the bottom elevation of the steel arch frame (17) is higher than or equal to the elevation of the tunnel axis of the tunnel (6).

7. The excavation support structure of the water inlet and the hole face sitting on the soft foundation according to claim 1 is characterized by: A pipe shed (14) is obliquely installed in the end surface of the tunnel face retaining wall (5) toward the inside of the tunnel (6), and the axis of the pipe shed (14) is inclined toward a side away from the tunnel (6) relative to the axial direction of the tunnel (6).

8. The excavation support structure of the water inlet and the hole face sitting on the soft foundation according to claim 1 is characterized by: The gentle slope (3) is provided with a gentle slope section drainage hole (8) extending into the soil body.

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