Foundation pit supporting structure in ultra-deep sludge state and earth excavation construction method

Abstract

The invention relates to the technical field of building construction, in particular to a foundation pit supporting structure in an ultra-deep sludge state and an earth excavation construction method.The foundation pit supporting structure in the ultra-deep sludge state comprises a foundation soil nailing wall, the foundation soil nailing wall comprises a slope surface and a platform surface, a single-shaft stirring pile waterproof curtain is arranged below the platform surface, and a reinforcing soil body is arranged below the single-shaft stirring pile waterproof curtain at the bottom; a positioning ring is arranged on the top surface of the platform surface; the construction method has the beneficial effects that the positioning ring is arranged on the platform surface, and the inner ring opening of the positioning ring definitely defines an area in which the single-shaft stirring pile is required to be constructed as the water cut-off curtain. The conical heads fixed to the bottom face of the lifting ring penetrate through the bottom plate of the positioning ring and then are inserted into the surface of the platform face, the positioning ring is firmly limited to the platform face, displacement of the positioning ring in the construction process is effectively avoided, and therefore precise fixed-point limiting of the single-shaft stirring pile serving as a water cut-off curtain in construction is achieved; the construction quality of the water cut-off curtain is guaranteed, and the waterproof performance of the foundation pit is improved.

Description

Technical Field

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[0001] The present invention relates to the technical field of building construction, and specifically to a foundation pit support structure and an earthwork excavation construction method in a super-deep silt state. Background Technique

[0002] In the construction of foundation pits in a super-deep silt state, many challenges are faced. Due to the extremely high water content of the silt layer, slope slippage is extremely likely to occur during the excavation process, which poses a serious threat to the stability of the foundation pit. To prevent such problems from occurring, soil reinforcement measures are usually required, and the single-axis mixing pile is one of the commonly used reinforcement means.

[0003] When using a single-axis mixing pile for soil reinforcement, dry operation is required to ensure the construction quality of the mixing pile. At the same time, a single-axis mixing pile is set at the slope platform as a water cutoff curtain to prevent groundwater from seeping into the foundation pit. To ensure the water cutoff effect, the mixing piles need to be mutually interlocked. However, in the actual construction process, how to ensure that the single-axis mixing pile can be accurately constructed as a water cutoff curtain and avoid the displacement of the positioning ring on the platform surface, so as to achieve fixed-point limiting, is an urgent problem to be solved. If the positioning is inaccurate, it may cause holes in the water cutoff curtain, affecting the waterproof effect of the foundation pit, and further affecting the safety and stability of the entire foundation pit project. Summary of the Invention

[0004] The purpose of the present invention is to provide a foundation pit support structure and an earthwork excavation construction method in a super-deep silt state to solve the problems raised in the above background technique.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A foundation pit support structure in a super-deep silt state, including a foundation soil nail wall. The foundation soil nail wall includes a slope surface and a platform surface. Below the platform surface, there is a single-axis mixing pile water cutoff curtain. Below the bottom single-axis mixing pile water cutoff curtain, there is a reinforced soil body. On the top surface of the platform surface, there is a positioning ring. The positioning ring is a "convex"-shaped circular ring plate. A lifting ring is sleeved on the top of the positioning ring. A plurality of cone heads are fixed on the bottom surface of the lifting ring. The cone heads penetrate through the bottom plate of the positioning ring and are inserted into the surface of the platform surface. The top of the lifting ring is rotatably connected to a screwed ring, and the screwed ring is sleeved and screwed on the top end of the foundation soil nail wall.

[0006] Preferably, a plurality of through holes are opened on the bottom plate of the positioning ring, and the through holes and the cone heads correspond one by one. The height of the cone head is greater than the thickness of the bottom plate of the positioning ring. The cone head penetrates through the through hole and is inserted into the top of the platform surface.

[0007] Preferably, the cone head is of a cylindrical structure. A conical structure is integrally formed at the bottom end of the cone head. A plurality of card slots are opened on the rod body of the cone head. The card slots are annular grooves, and the plurality of card slots are arranged in a vertical distribution.

[0008] Preferably, the outer diameter of the lifting ring is smaller than the outer diameter of the base plate of the positioning ring. The top surface of the lifting ring is provided with a slot, which is an annular groove. A connecting plate is inserted into the inside of the slot. The connecting plate is a "convex" shaped circular plate. The top of the connecting plate is fixed to the bottom surface of the screw ring. Both the inner and outer annular surfaces of the slot are fixed with retaining rings at the groove opening. The two retaining rings are of different sizes.

[0009] Preferably, the inner ring surface of the screw ring is provided with an internal thread, and the top plate of the positioning ring is provided with an external thread on the side wall, with the external thread and the internal thread engaging and connecting.

[0010] Preferably, the outer wall of the screw ring is fixed with two elastic traction plates, which are arc-shaped and symmetrically distributed about the screw ring. The bottom surface of the positioning ring has a bottom groove at the outer ring, which is an annular groove. The bottom end of the elastic traction plate is integrally formed with a retaining strip, which is an arc strip with a right-angled trapezoidal end face. One side of the retaining strip is inserted into the bottom groove, and the other side of the bottom end of the elastic traction plate is fixed with a pull ring.

[0011] Preferably, the screw ring has multiple notches on the outer ring of the top surface, a reserved groove on the bottom surface of the notch, and a limiting shaft is fixed between two parallel sidewalls of the notch. A handle is inserted into the notch, the limiting shaft passes through one end of the handle, and a rubber clip is fixed to one end of the handle. The rubber clip is held between the handle and the sidewall of the notch and undergoes elastic deformation.

[0012] A method for earthwork excavation includes the following steps: Based on the excavation depth and geotechnical investigation report, the pit height is divided into two slopes, with a 1500mm wide platform reserved between the first and second slopes. Single-axis cement-soil mixing piles are used to reinforce the weak parts of the soil around the pit, the pit within the pit, and the vehicle ramp. Foundation soil nailing walls are installed at the slopes for reinforcement. Positioning rings are installed on the platform for the construction of double-row single-axis cement-soil mixing piles.

[0013] Compared with the prior art, the beneficial effects of the present invention are: The present invention proposes a construction method for foundation pit support structure and earthwork excavation in ultra-deep silt conditions. By setting a positioning ring on the platform surface, the inner opening of the positioning ring clearly defines the area where single-axis mixing piles will be used as a cutoff wall. Multiple cones fixed to the bottom of a lifting ring penetrate the base plate of the positioning ring and are then inserted into the platform surface, firmly limiting the positioning ring to the platform surface. This effectively prevents displacement of the positioning ring during construction, thereby achieving precise positioning of the single-axis mixing piles as a cutoff wall, ensuring the construction quality of the cutoff wall, and improving the waterproofing performance of the foundation pit.

[0014] A threaded ring is rotatably connected to the top of the lifting ring, which is screwed onto the top of the foundation soil nailing wall. By turning the handle, the lifting ring extends from the notch. Holding the handle with both hands, the threaded ring is turned downwards along the positioning ring. As the threaded ring falls along the positioning ring, it pushes the lifting ring down, thus inserting the cone head into the platform surface. When the threaded ring is unscrewed, the lifting ring is lifted by the connecting plate, allowing the lifting ring to pull multiple cone heads out of the platform surface. This operation method is simple and convenient, greatly improving construction efficiency and reducing the labor intensity of construction workers.

[0015] Two elastic traction plates, symmetrically distributed around the bolted ring, are fixed to the outer wall of the bolted ring. When the bolted ring falls along the foundation soil nailing wall, pushing the lifting ring to overlap the base plate of the positioning ring, the integrally formed retaining strip at the bottom end of the elastic traction plate is inserted into the bottom groove of the outer ring of the positioning ring. By tractioning the bolted ring with the elastic traction plates, upward loosening of the bolted ring is effectively prevented, ensuring stable compression of the lifting ring by the bolted ring, further guaranteeing the limiting effect of the positioning ring, and enhancing the stability of the entire foundation pit support structure.

[0016] When the two sets of positioning rings are not installed, they can be stacked. In this case, the cone at the bottom of the upper positioning ring inserts into the slot on the top lifting ring of the lower positioning ring, thus achieving an aligned stacking of the two sets of positioning rings. This storage method saves space, facilitates the transportation and storage of positioning rings, and improves the utilization rate of the construction site. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 for Figure 1 Sectional view of the structure at point AA; Figure 3 for Figure 2 Enlarged schematic diagram of the structure at point B; Figure 4 This is a schematic diagram of the connection structure between the positioning ring and the screw ring of the present invention; Figure 5 This is a schematic diagram of the lifting ring structure of the present invention; Figure 6 This is a schematic diagram of the screw ring structure of the present invention.

[0018] In the diagram: 1. Foundation soil nailing wall, 101. Slope surface, 102. Platform surface, 2. Single-axis mixing pile water-stop curtain, 3. Reinforced soil, 4. Positioning ring, 401. Perforation, 402. Bottom trench, 5. Lifting ring, 501. Cone head, 502. Slot, 503. Retaining ring, 504. Threaded ring, 6. Connecting plate, 601. Notched groove, 602. Reserved groove, 603. Limiting shaft, 604. Handle, 605. Rubber clamp strip, 606. Elastic traction plate, 7. Clamping strip, 701. Pull ring, 702. Detailed Implementation

[0019] In order to clearly and completely describe the objectives, technical solutions of the present invention and make the advantages more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are part of the embodiments of the present invention, rather than all of the embodiments. They are only used to explain the embodiments of the present invention and are not used to limit the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0020] Please refer to Figures 1 to 6 , the present invention provides a technical solution: a foundation pit support structure in a super-deep silt state, including a foundation soil nail wall 1. The foundation soil nail wall 1 includes a slope surface 101 and a platform surface 102. Below the platform surface 102, there is a single-axis mixing pile water-stop curtain 2. Below the bottom single-axis mixing pile water-stop curtain 2, there is a reinforced soil body 3. On the top surface of the platform surface 102, there is a positioning ring 4. The positioning ring 4 is a "convex"-shaped circular ring plate. A lifting ring 5 is sleeved on the top of the positioning ring 4. A plurality of conical heads 501 are fixed on the bottom surface of the lifting ring 5. The conical heads 501 penetrate through the bottom plate of the positioning ring 4 and are inserted into the surface of the platform surface 102. A plurality of through holes 401 are opened on the bottom plate of the positioning ring 4. The through holes 401 and the conical heads 501 correspond one by one. The height of the conical head 501 is greater than the thickness of the bottom plate of the positioning ring 4. After the conical head 501 penetrates through the through hole 401, it is inserted into the top of the platform surface 102; the conical head 501 is of a cylindrical structure, and a conical structure is integrally formed at the bottom end of the conical head 501. A plurality of clamping grooves 502 are opened on the rod body of the conical head 501. The clamping grooves 502 are annular grooves, and the plurality of clamping grooves 502 are arranged vertically.

[0021] Since the moisture content of the silt layer is high for soil reinforcement, in order to prevent slope sliding during the excavation process, dry operation is adopted to ensure the construction quality of the mixing piles; 2 rows of single-axis mixing piles are arranged at the slope platform as a water-stop curtain. To ensure the water-stop effect, the mixing piles are mutually occluded; the positioning ring 4 is placed on the platform surface 102. The inner ring opening of the positioning ring 4 is the area where the single-axis mixing pile is required for water-stop curtain construction. The lifting ring 5 is pressed downward so that the conical head 501 is inserted into the platform surface 102, thereby limiting the positioning ring 4 on the platform surface 102 and preventing the positioning ring 4 from shifting on the platform surface 102, thus realizing the fixed-point limit of the single-axis mixing pile for water-stop curtain construction.

[0022] In order to facilitate pushing the lifting ring 5 downward to drive the conical head 501 to be inserted into the surface of the platform surface 102, it is proposed that: A screw ring 6 is rotatably connected to the top of the lifting ring 5, and the screw ring 6 is screwed onto the top of the foundation soil nailing wall 1. The outer diameter of the lifting ring 5 is smaller than the outer diameter of the bottom plate of the positioning ring 4. A slot 503 is provided on the top surface of the lifting ring 5. The slot 503 is an annular groove. A connecting plate 601 is inserted into the inside of the slot 503. The connecting plate 601 is a "convex" shaped annular plate. The top of the connecting plate 601 is fixed to the bottom surface of the screw ring 6. A retaining ring 504 is fixed at the groove opening on both the inner and outer annular surfaces of the slot 503. The two retaining rings 504 are of different sizes. The inner annular surface of the screw ring 6 is provided with an inner... The top plate of the positioning ring 4 has external threads on its side wall, and the external threads and internal threads are connected in a mating manner; the screw ring 6 has multiple notches 602 on the outer ring of the top surface, and a reserved groove 603 is opened on the bottom surface of the notch 602. A limiting shaft 604 is fixed between two parallel side walls of the notch 602. A handle 605 is inserted into the notch 602. The limiting shaft 604 passes through one end of the handle 605. A rubber clamp 606 is fixed to one end of the handle 605. The rubber clamp 606 is clamped between the handle 605 and the side wall of the notch 602 and undergoes elastic deformation.

[0023] The handle 605 is rotated around the limiting shaft 604 on the outside of the notch 602. When the handle 605 extends out of the notch 602, both hands hold the handle 605 and rotate the screw ring 6 downward along the positioning ring 4. When the screw ring 6 falls along the positioning ring 4, it pushes the lifting ring 5 down, thereby inserting the cone 501 into the platform surface 102. When the screw ring 6 is tightened back, the lifting ring 5 is lifted by the connecting plate 601, thereby pulling multiple cones 501 out of the platform surface 102. When the two sets of positioning rings 4 are not installed, the two sets of positioning rings 4 can be stacked. At this time, the cone 501 at the bottom of the upper positioning ring 4 is inserted into the slot 503 on the top lifting ring 5 of the lower positioning ring 4, so that the two sets of positioning rings 4 are stacked in an upright position.

[0024] To achieve the relaxation limit after the screw ring 6 is unscrewed, the following is proposed: Two elastic traction plates 7 are fixed to the outer wall of the screw ring 6. The elastic traction plates 7 are arc-shaped and the two elastic traction plates 7 are symmetrically distributed about the screw ring 6. The bottom surface of the positioning ring 4 has a bottom groove 402 at the outer ring. The bottom groove 402 is an annular groove. The bottom end of the elastic traction plate 7 is integrally formed with a retaining strip 701. The retaining strip 701 is an arc strip with a right-angled trapezoidal end face. One side of the retaining strip 701 is inserted into the bottom groove 402. The other side of the bottom end of the elastic traction plate 7 is fixed with a pull ring 702.

[0025] When the bolted ring 6 falls down along the foundation soil nail wall 1 and pushes the lifting ring 5 to overlap the bottom plate of the positioning ring 4, the clamping strip 701 is inserted into the bottom groove 402. The bolted ring 6 is pulled by the elastic traction plate 7 to prevent the bolted ring 6 from loosening upward, thereby ensuring that the bolted ring 6 stably squeezes the lifting ring 5.

[0026] Method of using foundation pit support structure in ultra-deep silt state: Given the high water content of the silt layer, in order to prevent slope slip during excavation, dry operation is adopted for soil reinforcement to ensure the construction quality of the mixing piles. Two rows of single-axis mixing piles are set at the slope platform as a water cutoff curtain, ensuring that the mixing piles are interlocked with each other to guarantee the water cutoff effect. Place the positioning ring 4 on the platform surface 102, making the inner ring opening of the positioning ring 4 align with the area where single-axis mixing piles are to be constructed as a water cutoff curtain. Insert the connecting disc 601 into the slot 503 opened on the top surface of the lifting ring 5. Since retaining rings 504 with different sizes are fixed at the notch of the inner ring surface and the outer ring surface of the slot 503, it can ensure the stable insertion of the connecting disc 601. The connecting disc 601 is a "convex"-shaped circular ring plate, and its top end is fixed to the bottom surface of the screwed ring 6. The screwed ring 6 is sleeved and screwed on the top end of the foundation soil nail wall 1, and the inner ring surface of the screwed ring 6 has internal threads. The top plate body of the positioning ring 4 has external threads on the side wall, and the two are connected in cooperation.拨动把手605,使其以限位轴604为中心轴向缺槽602的外侧转动,当把手605从缺槽602伸出后,双手均手持把手605拨动螺接环6沿着定位环4向下旋拧。(此句原文表述有误,已修正为:Pull the handle 605 to rotate it axially outward of the notch 602 with the limiting shaft 604 as the center. When the handle 605 extends out of the notch 602, hold the handle 605 with both hands and turn the screwed ring 6 downward along the positioning ring 4.)When the screwed ring 6 drops along the positioning ring 4, it squeezes and pushes the lifting ring 5 to drop. The multiple cone heads 501 fixed to the bottom surface of the lifting ring 5 penetrate through the corresponding perforations 401 opened on the bottom plate of the positioning ring 4 and are inserted into the surface of the platform surface 102, thereby realizing the limitation of the positioning ring 4 on the platform surface 102 and preventing the positioning ring 4 from shifting on the platform surface 102, achieving fixed-point limitation for the construction of single-axis mixing piles as a water cutoff curtain. The cone head 501 is of a cylindrical structure, with a conical structure integrally formed at the bottom end, and multiple annular grooves and card slots 502 arranged vertically are opened on the rod body. When the screwed ring 6 drops along the foundation soil nail wall 1 and squeezes and pushes the lifting ring 5 to overlap on the bottom plate of the positioning ring 4, two elastic traction pieces 7 symmetrically distributed about the screwed ring 6 and fixed to the outer wall of the screwed ring 6, and the arc-shaped strip card slots 701 with a right-angled trapezoid end face integrally formed at their bottom ends are inserted into the annular bottom groove 402 opened at the outer ring of the bottom surface of the positioning ring 4. The screwed ring 6 is pulled by the elastic traction piece 7 to prevent the screwed ring 6 from loosening upward and ensure the stable extrusion of the screwed ring 6 on the lifting ring 5. The pull ring 702 fixed to the other side of the bottom end of the elastic traction piece 7 can be used when the limit needs to be released. When the construction of the single-axis mixing pile as a water cutoff curtain is completed, turn the screwed ring 6 back, and through the connecting disc 601, pull the lifting ring 5 to lift, thereby realizing the lifting of the lifting ring 5 to pull out the multiple cone heads 501 from the platform surface 102. When the two groups of positioning rings 4 are not installed, the two groups of positioning rings 4 can be stacked. At this time, the cone heads 501 at the bottom of the upper positioning ring 4 are inserted into the slots 503 on the lifting ring 5 at the top of the lower positioning ring 4, realizing the correct stacking of the two groups of positioning rings 4.

[0027] Example 2, based on Example 1, proposes: A method for earth excavation construction, including the following steps: Based on the excavation depth and geotechnical investigation report, the pit height is divided into two slopes, with a 1500mm wide platform 102 reserved between the first and second slopes. Single-axis cement-soil mixing piles are used to reinforce the weak parts of the soil around the pit, the pit within the pit, and the vehicle ramp. Foundation soil nailing walls 1 are installed at the slope for reinforcement. Positioning rings 4 are installed on the platform 102 for the construction of double-row single-axis cement-soil mixing piles.

[0028] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A foundation pit support structure in ultra-deep silt conditions, comprising a foundation soil nailing wall (1), the foundation soil nailing wall (1) comprising a slope surface (101) and a platform surface (102), a single-axis mixing pile water-stop curtain (2) provided below the platform surface (102), and a reinforced soil body (3) provided below the single-axis mixing pile water-stop curtain (2) at the bottom, characterized in that: A positioning ring (4) is provided on the top surface of the platform surface (102). The positioning ring (4) is a "convex"-shaped circular ring plate. A lifting ring (5) is sleeved on the top of the positioning ring (4). A plurality of conical heads (501) are fixed on the bottom surface of the lifting ring (5). The conical heads (501) penetrate through the bottom plate of the positioning ring (4) and are inserted into the surface of the platform surface (102). A screwing ring (6) is rotatably connected to the top of the lifting ring (5). The screwing ring (6) is sleeved and screwed on the top end of the basic soil nailing wall (1).

2. The foundation pit support structure under ultra-deep silt conditions according to claim 1, characterized in that: A plurality of through holes (401) are formed in the bottom plate of the positioning ring (4). The through holes (401) and the conical heads (501) correspond to each other one by one. The height of the conical head (501) is greater than the thickness of the bottom plate of the positioning ring (4). The conical head (501) penetrates through the through hole (401) and is inserted into the top of the platform surface (102).

3. The foundation pit support structure under ultra-deep silt conditions according to claim 2, characterized in that: The conical head (501) has a cylindrical structure. A conical structure is integrally formed at the bottom end of the conical head (501). A plurality of card slots (502) are formed on the rod body of the conical head (501). The card slots (502) are annular grooves. The plurality of card slots (502) are arranged vertically.

4. The foundation pit support structure under ultra-deep silt conditions according to claim 1, characterized in that: The outer diameter of the lifting ring (5) is smaller than the outer diameter of the bottom plate of the positioning ring (4). A slot (503) is formed on the top surface of the lifting ring (5). The slot (503) is an annular groove. A connecting disc (601) is inserted into the slot (503). The connecting disc (601) is a "convex"-shaped circular ring plate. The top end of the connecting disc (601) is fixed to the bottom surface of the screwing ring (6). Retaining rings (504) are fixed at the inner ring surface and the outer ring surface of the slot (503) at the slot opening. The two retaining rings (504) have different sizes.

5. The foundation pit support structure under ultra-deep silt conditions according to claim 1, characterized in that: Internal threads are provided on the inner ring surface of the screwing ring (6). External threads are provided on the side wall of the top plate of the positioning ring (4). The external threads and the internal threads are in mating connection.

6. The foundation pit support structure under ultra-deep silt conditions according to claim 1, characterized in that: Two elastic traction pieces (7) are fixed on the outer wall of the screwing ring (6). The elastic traction pieces (7) are circular arc-shaped pieces. The two elastic traction pieces (7) are symmetrically distributed with respect to the screwing ring (6). A bottom groove (402) is formed at the outer ring of the bottom surface of the positioning ring (4). The bottom groove (402) is an annular groove. A card strip (701) is integrally formed at the bottom end of the elastic traction piece (7). The card strip (701) is an arc-shaped strip with a right trapezoid end face. One side of the card strip (701) is inserted into the bottom groove (4). The other side of the bottom end of the elastic traction piece (7) is fixed with a pull ring (702).

7. The foundation pit support structure under ultra-deep silt conditions according to claim 1, characterized in that: A plurality of missing grooves (602) are formed at the outer ring of the top surface of the screwing ring (6). A reserved groove (603) is formed at the bottom surface of the missing groove (602). A limiting shaft (604) is fixed between the two parallel side walls of the missing groove (602). A handle (605) is inserted into the missing groove (602). The limiting shaft (604) penetrates through one end of the handle (605). A rubber clamping strip (6) is fixed at one end of the handle (605). The rubber clamping strip (606) is elastically deformed when clamped between the handle (605) and the side wall of the missing groove (602).

8. A method for earthwork excavation, employing the foundation pit support structure in ultra-deep silt conditions as described in any one of claims 1-7, characterized in that: The method includes the following steps: Based on the excavation depth and geotechnical investigation report, the height of the foundation pit is divided into two sections for sloping. A platform surface (102) with a width of 1500mm is reserved between the first and second slopes. Single-axis cement-soil mixing piles are used to reinforce the weak parts of the soil around the foundation pit, the pit within the pit, and the car ramp. Foundation soil nailing walls (1) are set up at the slope for reinforcement. Positioning rings (4) are installed on the platform surface (102) for the construction of double-row single-axis cement-soil mixing piles.

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