Permanent foundation pit supporting anti-seepage structure under high hole exposure rate and construction method

Abstract

The invention belongs to the field of karst engineering, and particularly relates to a permanent foundation pit supporting anti-seepage structure and a construction method.The permanent foundation pit supporting anti-seepage structure comprises a foundation pit body, an anti-seepage wall is arranged in the foundation pit body, an SWM construction method pile is arranged on the inner side of the anti-seepage wall, solidified soil is arranged on the inner side of the SWM construction method pile, and a waterproof layer is arranged on the inner side of the solidified soil; a structural wall body is arranged on the inner side of the waterproof layer, and a supporting assembly is arranged on the inner side of the structural wall body and used for supporting the structural wall body to improve the stability of the structural wall body; the material of the waterproof curtain is improved, cement grout is replaced with a mixture of natural sodium-based bentonite and cement, the characteristic that bentonite swells when encountering water to form colloid is utilized, the solution (soil) hole can be effectively blocked, the colloid formed by the bentonite is poor in fluidity and can be easily combined with surrounding soil once being formed, and therefore the waterproof curtain is not prone to falling off. Therefore, the liquid is prevented from overflowing out of a project site in the subsequent process, and potential safety risks are avoided.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of karst engineering, and particularly relates to a permanent foundation pit support anti-seepage structure under high cave rate and a construction method. BACKGROUND

[0002] In urban areas, when a house construction construction foundation pit support engineering is carried out in a karst landform region (limestone region), high cave rate geological conditions are often encountered, the terrain is narrow and adjacent to surrounding buildings, and in the construction process, cement slurry leakage is prone to occur in karst engineering, water-rich strata, especially water-rich high-permeability sandy strata, which can even lead to serious hole collapse, and corresponding foundation pit support technology needs to be used.

[0003] Common foundation pit support construction technology generally uses cement as a guniting material, and forms a cement-soil wall by mixing and stirring the cement slurry with the soil to achieve a water stopping function. However, the groundwater in limestone regions is very abundant, which can easily dilute the cement slurry, so that the actual water stopping effect cannot meet the design standard.

[0004] In addition, conventional side wall waterproof materials usually do not use root penetration resistant types, but in actual application, the owner often plants greenery in this area in pursuit of overall aesthetics. Due to the inherent limitations of the side wall coiled material, the plant roots can penetrate the material and damage its waterproof performance.

[0005] Therefore, the application provides a permanent foundation pit support anti-seepage structure under high cave rate and a construction method. SUMMARY

[0006] In order to make up for the deficiencies of the prior art and solve at least one technical problem raised in the background art.

[0007] The technical scheme adopted by the application to solve the technical problems is: a permanent foundation pit support anti-seepage structure under high cave rate, comprising a foundation pit body, an anti-seepage wall arranged inside the foundation pit body, an SWM method pile arranged on the inner side of the anti-seepage wall, solidified soil arranged on the inner side of the SWM method pile, a waterproof layer arranged on the inner side of the solidified soil, and a structural wall arranged on the inner side of the waterproof layer.

[0008] The inner side of the structural wall is provided with a support assembly for supporting the structural wall to improve its stability.

[0009] Preferably, the waterproof layer comprises a waterproof coiled material and a waterproof protective layer, the waterproof coiled material is a waterproof coiled material layer, and the waterproof protective layer is a waterproof protective layer.

[0010] Preferably, the support assembly comprises a plurality of mounting plates fixed to the inner side of the structural wall, a support shell rotatably connected to one side of the mounting plate, a pull rod slidingly inserted into the inner cavity of the support shell, and an anchor plate rotatably connected to the bottom of the pull rod.

[0011] Preferably, the inner cavity of the support shell is in T-shaped cross section, and the pull rod is in T-shaped cross section.

[0012] Preferably, the support assembly further comprises a plurality of positioning holes communicated with the top of the inner cavity of the support shell, an opening formed on the surface of the pull rod, an inner compartment formed in the pull rod at the bottom of the opening, an insertion block inserted into the inner cavity of the opening, a connecting rod fixed to the bottom of the insertion block, a connecting rod slidingly inserted between the opening and the connecting rod, a connecting block fixed to the bottom of the connecting rod, and a limiting component acting on the connecting block, the bottom of the connecting rod is fixed to the bottom of the inner wall of the opening, and the top of the connecting rod is fixed to the surface of the connecting rod.

[0013] Preferably, the limiting component comprises a first threaded rod slidingly inserted into the inner cavity of the inner compartment and a first threaded rod threadedly connected to the inner wall of the support shell, one end of the first threaded rod is rotatably connected to the surface of the abutting block, one side of the top of the abutting block is in a beveled surface, and the bottom of the connecting block is in a beveled surface.

[0014] Preferably, the support assembly further comprises a central shaft arranged between the four anchor plates, a limiting groove formed on both sides of the central shaft, a sliding disc slidingly inserted into the inner cavity of the limiting groove, a second threaded rod rotatably connected to one side of the sliding disc, a threaded hole formed on one side of the four anchor plates, and a second spring fixed to the side of the sliding disc away from the adjacent position of the second threaded rod, one side of the second spring is fixed to the inner wall of the limiting groove, one side of the second threaded rod extends to the inside of the adjacent position of the threaded hole, the support assembly further comprises a guide rod penetratingly inserted into the sliding disc at the upper and lower ends of the second threaded rod, and both sides of the guide rod are fixed to the inner wall of the limiting groove.

[0015] The construction method of the permanent foundation pit support anti-seepage structure, which adopts the permanent foundation pit support anti-seepage structure, comprises the following steps:

[0016] S1: using a double-pipe rotary jet pile machine technology to construct a seepage prevention wall;

[0017] S2: inserting an I-steel into the pile body formed by a triaxial mixing pile machine to construct a SWM method pile;

[0018] S3: the structural wall is made of concrete with a permeability resistance grade of C to ensure the compactness of the concrete pouring and vibrating process;

[0019] S4: After the surface of the structural wall is treated, waterproof membrane is laid to ensure there are no hollow areas, and then a waterproof protective layer is laid.

[0020] S5: Clean the side wall base, carry out the pouring of solidified soil, and after the pouring is completed, carry out appropriate curing measures;

[0021] S6: Install support components to support the structural wall.

[0022] The beneficial effects of this invention are as follows:

[0023] 1. By improving the material of the water-stop curtain, the cement grout is replaced with a mixture of natural sodium bentonite and cement. The property of bentonite to expand when it comes into contact with water and form a colloid can effectively seal the karst (soil) cave. It has a better water-stopping effect and cost-effectiveness than the traditional cement grouting method for karst caves. It also has less disturbance to the surrounding environment and is more adaptable to old urban areas and complex geological scenarios.

[0024] 2. Because the colloid formed by bentonite has poor fluidity and easily combines with the surrounding soil once formed, it ensures that the liquid will not overflow the project site in the subsequent process, avoiding potential safety risks and further reducing the impact on the surrounding environment.

[0025] 3. Mineral-based cementitious solidifying agents are used to form solidified soil from waste engineering mud. The resulting material is similar to foamed concrete, which effectively solves the problem of insufficient backfill compaction caused by narrow side wall space.

[0026] 4. The sidewall waterproofing material uses solidified soil, which, after hardening, not only effectively protects the waterproofing material but also has its own seepage prevention function. Attached Figure Description

[0027] The invention will now be further described with reference to the accompanying drawings.

[0028] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0029] Figure 2 In this invention Figure 1 Enlarged structural diagram at point A;

[0030] Figure 3 In this invention Figure 1 Enlarged structural diagram at point B;

[0031] Figure 4 This is a three-dimensional structural diagram of the support component in this invention;

[0032] Figure 5 This is a partial three-dimensional structural cross-sectional view of the support component in this invention;

[0033] Figure 6 In this invention Figure 5 Enlarged schematic diagram of the structure at point C;

[0034] Figure 7 This is a three-dimensional cross-sectional view of the central axis in this invention;

[0035] Figure 8 This is a schematic diagram of the construction method of the present invention.

[0036] In the diagram: 1. Excavation pit body; 2. Anti-seepage wall; 3. SWM method pile; 4. Stabilized soil; 5. Waterproof layer; 51. Waterproof membrane; 52. Waterproof protective layer; 6. Structural wall; 7. Support shell; 8. Mounting plate; 9. Tie rod; 10. Anchor plate; 11. Positioning hole; 12. Opening; 13. Insert block; 14. Connecting rod; 15. First spring; 16. Connecting block; 17. Inner chamber; 18. Abutment block; 19. First threaded rod; 20. Central shaft; 21. Second threaded rod; 22. Threaded hole; 23. Limiting groove; 24. Sliding disc; 25. Guide rod; 26. Second spring. Detailed Implementation

[0037] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0038] Example 1:

[0039] like Figures 1 to 7 As shown, the permanent foundation pit support seepage prevention structure with high hole exposure rate according to the embodiment of the present invention includes a foundation pit body 1, a seepage prevention wall 2 is provided inside the foundation pit body 1, an SWM method pile 3 is provided inside the seepage prevention wall 2, a solidified soil 4 is provided inside the SWM method pile 3, a waterproof layer 5 is provided inside the solidified soil 4, a structural wall 6 is provided inside the waterproof layer 5, and a support component is provided inside the structural wall 6 to support the structural wall 6 and improve its stability.

[0040] The waterproof layer 5 includes a waterproof membrane 51 and a waterproof protective layer 52. The waterproof membrane 51 is a waterproof membrane layer, and the waterproof protective layer 52 is a waterproof protective layer.

[0041] The seepage-proof wall 2 replaces the traditional cement mixing pile as the water-stopping curtain. At the same time, the improved material is changed from cement grout to natural sodium bentonite + 10% cement. The grouting pressure is 18-22 MPa. A double-pipe jet grouting machine is used. The SWM method pile 3 adopts a three-axis mixing pile + I-beam to improve the overall rigidity of the foundation pit. The solidified soil 4 is formed by mixing engineering waste soil and grout, and adding mineral-based cementitious curing agents. The waterproof layer 5 adopts a double-layer structure. The waterproof membrane 51 is a fiber-reinforced root-penetration resistant modified bitumen waterproof membrane 2mm thick. The waterproof protective layer 52 is an ALC precast panel. The structural wall 6 is cast with anti-seepage C30 concrete.

[0042] By improving the materials of the waterproofing curtain, cement grout is replaced with a mixture of natural sodium-based bentonite and cement. Utilizing the property of bentonite to swell and form a colloid upon contact with water, cavities in the soluble soil can be effectively sealed. Because the bentonite colloid has poor fluidity and easily combines with the surrounding soil once formed, it ensures that liquid will not overflow the project site during subsequent processes, avoiding potential safety risks. Mineral-based gelling agents are used to form solidified soil from waste engineering slurry. The resulting material is similar to foamed concrete, effectively solving the problem of insufficient backfill compaction caused by narrow sidewall spaces. The solidified soil used for the sidewall waterproofing not only effectively protects the waterproofing material after hardening but also possesses its own seepage-proof function.

[0043] This can solve the problem of cement grout leakage that is prone to occur in karst engineering and water-rich strata, especially water-rich and highly permeable sandy strata, which can lead to serious hole collapse. Compared with the traditional cement grouting method for karst caves, it has better water-stopping effect and cost-effectiveness, and causes less disturbance to the surrounding environment. It is also more adaptable to old urban areas and complex geological scenarios.

[0044] like Figures 1 to 7 As shown, the support assembly includes multiple mounting plates 8 fixed to the inner side of the structural wall 6, a support housing 7 rotatably connected to one side of the mounting plates 8, a tie rod 9 slidably inserted into the inner cavity of the support housing 7, and an anchor plate 10 rotatably connected to the bottom of the tie rod 9. The cross-section of the inner cavity of the support housing 7 is T-shaped, and the cross-section of the tie rod 9 is T-shaped.

[0045] After the structural wall 6 is poured, a set of screw holes are pre-set on the inner side of the structural wall 6, and the mounting plate 8 is fixed to the inner side of the structural wall 6 with bolts. Then, the length of the tie rod 9 inside the support shell 7 is adjusted, and the angle of the anchor plate 10 is adjusted by rotating the anchor plate 10 so that it is parallel to the bottom surface of the foundation pit. Since the total length of the tie rod 9 and the support shell 7 can be adjusted, it can meet the needs of foundation pits of various depths. Then, the anchor rods pre-set on the surface of the anchor plate 10 are hammered into the soil deep in the foundation pit, which can support the structural wall 6, improve the stability of the structural wall 6, and prevent the structural wall 6 from deforming or cracking under stress. Furthermore, due to the shape setting of the inner cavity of the support shell 7 and the tie rod 9, the tie rod 9 can be prevented from detaching from the inner cavity of the support shell 7 by the contact between the top surface of the tie rod 9 and the bottom of the inner cavity of the support shell 7.

[0046] like Figures 1 to 7 As shown, the support assembly also includes multiple positioning holes 11 communicating with the top of the inner cavity of the support housing 7, an opening 12 on the surface of the pull rod 9, an inner compartment 17 located at the bottom of the opening 12 inside the pull rod 9, a plug 13 inserted into the inner cavity of the opening 12, a connecting rod 15 fixed to the bottom of the plug 13, a connecting rod 14 slidably inserted between the opening 12 and the connecting rod 15, a connecting block 16 fixed to the bottom of the connecting rod 14, and a limiting component acting on the connecting block 16. The bottom of the connecting rod 15 is fixed to the bottom of the inner wall of the opening 12, and the top of the connecting rod 14 is fixed to the surface of the connecting rod 14.

[0047] When the sliding rod 9 slides within the cavity of the support housing 7, the insertion block 13 slides into the opening 12 due to the contact between the inner wall of the positioning hole 11 and the inner wall of the support housing 7. This compresses the adjacent connecting rod 15, causing it to deform. Furthermore, the contact between the connecting rod 14 and the hole wall between the opening 12 and the connecting block 16 limits the insertion block 13. After adjusting the total length of the mounting plate 8 and the rod 9, the insertion block 13 is inserted into the cavity of the adjacent positioning hole 11 under the rebound force of the connecting rod 15. This positions the mounting plate 8 and, through the limiting component, contacts the connecting block 16, thus fixing the mounting plate 8 in the positioned position and ensuring that the total length of the mounting plate 8 and the rod 9 remains constant.

[0048] like Figures 1 to 7 As shown, the limiting components include a first threaded rod 19 that is slidably inserted into the inner cavity of the inner compartment 17 and a first threaded rod 19 that is threadedly connected to the inner wall of the support housing 7. One end of the first threaded rod 19 is rotatably connected to the surface of the abutment block 18. One side of the top of the abutment block 18 is inclined, and the bottom of the connecting block 16 is inclined.

[0049] After the insert 13 is inserted into the adjacent positioning hole 11 to limit the pull rod 9, the first threaded rod 19 is rotated to extend into the depth of the inner cavity of the support housing 7 through the cooperation of the threaded structure with the inner wall of the pull rod 9. Since the abutment block 18 is limited by the inner cavity of the inner chamber 17, the abutment block 18 moves towards the connecting block 16 until the top surface of the abutment block 18 abuts against the bottom surface of the connecting block 16. This limits the height of the insert 13 and the connecting rod 14. Since the abutment block 18 and the connecting block 16 are set at an angle, the contact area between the abutment block 18 and the surface of the connecting block 16 is increased, which improves the stability of the abutment block 18 supporting the connecting block 16. Furthermore, since the threaded structure of the first threaded rod 19 and the pull rod 9 can limit the position of the abutment block 18, the total length of the mounting plate 8 and the pull rod 9 remains constant.

[0050] like Figures 1 to 7 As shown, the support assembly also includes a central shaft 20 disposed between four sets of anchor plates 10, a limiting groove 23 opened on both sides of the central shaft 20, a sliding disk 24 slidably inserted into the cavity of the limiting groove 23, a second threaded rod 21 rotatably connected to one side of the sliding disk 24, a threaded hole 22 opened on one side of one of the four anchor plates 10, and a second spring 26 fixed to the side of the sliding disk 24 away from the adjacent position of the second threaded rod 21. One side of the second spring 26 is fixed to the inner wall of the limiting groove 23, and one side of the second threaded rod 21 extends into the interior of the adjacent position of the threaded hole 22.

[0051] After the multiple supporting shells 7 are installed, a central shaft 20 is placed between two anchor plates 10 located at the four corners of the inner side of the structural wall 6. The second threaded rod 21 and the sliding plate 24 are slid so that the second threaded rod 21 can approach the adjacent threaded hole 22. The second threaded rod 21 is rotated so that it can extend into the inside of the threaded hole 22 through the cooperation of the threaded structure between the second threaded rod 21 and the threaded hole 22. This allows the central shaft 20 to be fixed between the two adjacent anchor plates 10. Furthermore, the second spring 26 is provided and its rebound force ensures the vibration force at the four corners of the structural wall 6, thereby improving the stability of the four corners of the inner side of the structural wall 6.

[0052] like Figures 1 to 7 As shown, the support assembly also includes a guide rod 25 that is inserted through the sliding disk 24 at the upper and lower ends of the second threaded rod 21, and the two sides of the guide rod 25 are fixed to the inner wall of the limiting groove 23;

[0053] The guide rod 25 supports the sliding disk 24 and limits its movement, thus making the movement of the second threaded rod 21 and the sliding disk 24 more stable.

[0054] Example 2:

[0055] like Figure 8 As shown in Example 1, another embodiment of the present invention is as follows:

[0056] A construction method for a permanent foundation pit support and seepage prevention structure under high void ratio conditions, the method using the aforementioned permanent foundation pit support and seepage prevention structure includes the following steps:

[0057] S1` uses double-pipe jet grouting pile technology to construct a seepage-proof wall 2;

[0058] S2` uses a three-axis mixing pile machine to form a pile body, and then inserts an I-beam to construct the SWM method pile 3;

[0059] The S3` structural wall 6 uses C30 impermeability grade concrete to ensure the compactness of the concrete during pouring and vibration.

[0060] S4` After the surface treatment of the structural wall is completed, the waterproof membrane 51 is laid to ensure that there are no hollow areas, and then the waterproof protective layer 52 is laid.

[0061] S5` Clean the side wall base and pour the solidified soil 4. After pouring, carry out appropriate curing measures.

[0062] S6` provides support for the structural wall 6 by installing the support components.

[0063] The terms "front," "back," "left," "right," "top," and "bottom" all refer to the figures in the accompanying drawings. Figure 1 Based on the perspective of the observer, the side of the device facing the observer is defined as the front, the left side of the observer is defined as the left, and so on.

[0064] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A permanent foundation pit support and seepage prevention structure with high void ratio, characterized in that: The foundation pit includes a foundation pit body (1), an anti-seepage wall (2) is provided inside the foundation pit body (1), SWM method piles (3) are provided on the inner side of the anti-seepage wall (2), solidified soil (4) is provided on the inner side of the SWM method piles (3), a waterproof layer (5) is provided on the inner side of the solidified soil (4), and a structural wall (6) is provided on the inner side of the waterproof layer (5). The inner side of the structural wall (6) is provided with a support component to support the structural wall (6) and improve its stability.

2. The permanent foundation pit support and seepage prevention structure with high void ratio according to claim 1, characterized in that: The waterproof layer (5) includes a waterproof membrane (51) and a waterproof protective layer (52), wherein the waterproof membrane (51) is a waterproof membrane layer and the waterproof protective layer (52) is a waterproof protective layer.

3. The permanent foundation pit support and seepage prevention structure with high void ratio according to claim 1, characterized in that: The support assembly includes multiple mounting plates (8) fixed to the inner side of the structural wall (6), a support housing (7) rotatably connected to one side of the mounting plate (8), a tie rod (9) slidably inserted into the inner cavity of the support housing (7), and an anchor plate (10) rotatably connected to the bottom of the tie rod (9).

4. The permanent foundation pit support and seepage prevention structure with high void ratio according to claim 3, characterized in that: The cross-section of the inner cavity of the support housing (7) is T-shaped, and the cross-section of the tie rod (9) is T-shaped.

5. The permanent foundation pit support and seepage prevention structure with high void ratio according to claim 4, characterized in that: The support assembly further includes a plurality of positioning holes (11) communicating with the top of the inner cavity of the support housing (7), an opening (12) opened on the surface of the pull rod (9), an inner compartment (17) opened inside the pull rod (9) at the bottom of the opening (12), a plug (13) inserted into the inner cavity of the opening (12), a connecting rod (15) fixed to the bottom of the plug (13), a connecting rod (14) slidably inserted between the opening (12) and the connecting rod (15), a connecting block (16) fixed to the bottom of the connecting rod (14), and a limiting component acting on the connecting block (16). The bottom of the connecting rod (15) is fixed to the bottom of the inner wall of the opening (12), and the top of the connecting rod (14) is fixed to the surface of the connecting rod (14).

6. The permanent foundation pit support and seepage prevention structure with high void ratio according to claim 5, characterized in that: The limiting component includes a first threaded rod (19) slidably inserted into the inner cavity of the inner compartment (17) and a first threaded rod (19) threadedly connected to the inner wall of the supporting housing (7). One end of the first threaded rod (19) is rotatably connected to the surface of the abutment block (18). One side of the top of the abutment block (18) is inclined, and the bottom of the connecting block (16) is inclined.

7. The permanent foundation pit support and seepage prevention structure with high void ratio according to claim 6, characterized in that: The support assembly also includes a central shaft (20) disposed between four sets of anchor plates (10), a limiting groove (23) opened on both sides of the central shaft (20), a sliding disk (24) slidably inserted into the cavity of the limiting groove (23), a second threaded rod (21) rotatably connected to one side of the sliding disk (24), a threaded hole (22) opened on one side of one of the four anchor plates (10), and a second spring (26) fixed to the side of the sliding disk (24) away from the adjacent position of the second threaded rod (21). One side of the second spring (26) is fixed to the inner wall of the limiting groove (23), and one side of the second threaded rod (21) extends into the interior of the adjacent position of the threaded hole (22). The support assembly also includes a guide rod (25) inserted through the sliding disk (24) at the upper and lower ends of the second threaded rod (21). Both sides of the guide rod (25) are fixed to the inner wall of the limiting groove (23).

8. The construction method of the permanent foundation pit support and seepage prevention structure under high void ratio according to claim 7, wherein the method uses the permanent foundation pit support and seepage prevention structure according to claim 7, and includes the following steps: S1` uses double-pipe jet grouting pile technology to construct a seepage-proof wall (2); S2` is formed by a three-axis mixing pile machine, and then an I-beam is inserted to construct the SWM method pile (3); The S3` structural wall (6) uses C30 impermeability grade concrete to ensure the compactness of the concrete during pouring and vibration. After the structural wall surface is treated, waterproof membrane (51) is laid to ensure that there are no hollow areas, and then waterproof protective layer (52) is laid. S5` Clean the side wall base and pour the solidified soil (4). After pouring, carry out appropriate curing measures. S6` installs the support components to support the structural wall (6).

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