Double-pile-casing structure for shallow geology prone to hole collapse and construction method

Abstract

The invention discloses a double-pile-casing structure for shallow geology prone to hole collapse and a construction method, and belongs to the technical field of pile construction. The double-pile-casing structure comprises an outer casing, an outer casing flange connecting piece is arranged at the upper end of the outer casing, and through a structure provided with a mud blocking groove, the outer casing flange connecting piece can be connected with the outer casing flange connecting piece by rotating the mounting angle of two insertion ends; by arranging the first rotating rod and the second rotating rod, the inclination angle of the first rotating rod and the inclination angle of the second rotating rod can be controlled, so that when the inner sleeve is arranged, the connecting position between the inner sleeve and the outer sleeve can be stably supported, and concentricity is effectively kept; the connecting positions of the connecting ends and the inserting ends of the two inner sleeves can generate corresponding spaces at the positions of the mud blocking grooves according to different inserting depths of the connecting grooves and the connecting pieces, and cement mortar in the inner sleeves can flow into the spaces to be solidified into square concrete structures, so that the stability of the formed cement column can be improved.

Description

Technical Field

[0001] This invention relates to the field of pile construction technology, and more specifically, to a double-casing structure and construction method for shallow, easily collapsible geology. Background Technology

[0002] In the field of construction engineering, double-casing structures are a commonly used solution for construction in shallow, easily collapsible geological conditions. These structures aim to ensure the stability of the borehole wall during drilling, prevent borehole collapse, and thus guarantee the smooth progress of pile foundation construction. However, existing double-casing structures and construction methods for shallow, easily collapsible geological conditions have some problems that cannot be ignored.

[0003] Firstly, construction in shallow, easily collapsible geological conditions presents challenges. During the installation of the inner cylinder, the bottom soil layer is relatively soft, and without proper anchoring, the entire structure is prone to tilting. Controlling the concentricity between the inner and outer cylinders is also difficult. Traditional double-casing structures lack effective positioning and restraint measures. During descent, the inner cylinder is easily affected by geological conditions such as soil heterogeneity and groundwater flow, leading to displacement and making precise concentricity with the outer cylinder difficult. Poor concentricity not only affects the overall stability of the double-casing structure but can also cause uneven stress on the drill bit during drilling, resulting in borehole deviation and severely impacting the pile foundation's bearing capacity and project quality.

[0004] Secondly, the fixing effect of the inner cylinder during construction is not ideal. When constructing in shallow, easily collapsible geological conditions, sand is often filled between the inner and outer cylinders to stabilize the soil layer in order to protect the internal concrete from tipping over during the setting process. However, as a result, a support structure cannot be set between the inner and outer cylinders. Otherwise, the sand will make it difficult to pull out the inner cylinder when it is being recycled. Without a support structure, the inner cylinder will be tilted due to uneven stress on the buried sand. Summary of the Invention

[0005] The purpose of this invention is to provide a double-casing structure and construction method for shallow, easily collapsible geology, in order to solve the problems mentioned in the background art.

[0006] A double-casing structure and construction method for shallow, easily collapsible geology includes an outer casing, an outer casing flange connecting piece at the upper end of the outer casing, an insertion groove corresponding to the outer casing flange connecting piece at the lower end of the outer casing, an inner casing in the middle of the outer casing, a connecting end at the upper end of the inner casing, and an insertion end at the lower end of the inner casing. Multiple inner sleeves can be spliced ​​together. The upper flange of the uppermost inner sleeve is provided with a positioning tenon groove. The upper end of the positioning tenon groove is provided with a connecting end. A pair of stabilizing devices are symmetrically arranged on the upper side of the inner sleeve. The stabilizing device includes a reinforcing member fixedly installed on the top of the inner sleeve. A first rotating rod is rotatably mounted on the upper end of the reinforcing member, and a second rotating rod is rotatably mounted on the upper end of the first rotating rod. A limit mounting member is rotatably mounted on the upper end of the second rotating rod. A mudguard groove is fixedly mounted on the outer side of the second rotating rod, and a rotating member is rotatably mounted on the side of the mudguard groove. A buffer member is slidably mounted on the side of the rotating member.

[0007] Furthermore, the lower end of the outer sleeve is provided with several plug-in buckles at equal intervals, the upper end of the outer sleeve is provided with an outer sleeve flange connection groove corresponding to the plug-in buckles, the lower side of the outer sleeve is provided with several plug-in buckles at equal intervals, the side of the outer sleeve flange connection piece is provided with a circular groove corresponding to the plug-in buckles, and the multiple outer sleeves are fixedly connected by a first connecting bolt.

[0008] By adopting the above technical solution, multiple outer sleeves can be connected to each other by flanges. The outer sleeve flange connecting piece at the upper end of the outer sleeve can be inserted into the insertion groove opened at the bottom of another outer sleeve on the upper side, and then the two outer sleeves can be fixed by the outer sleeves.

[0009] Furthermore, the outer sleeves can be inserted into each other to provide support for the outer side of the pit inner wall. The upper end of the top outer sleeve is provided with a pressure-resistant outer sleeve component, which is connected to the upper flange of the outer sleeve. The lower end of the pressure-resistant outer sleeve component has the same insertion buckle as the lower end of the outer sleeve. The pressure-resistant outer sleeve component and the outer sleeve are fixedly connected by a first connecting bolt. The pressure-resistant outer sleeve component is a flared horn-shaped component made of tungsten carbide alloy (WC-Co).

[0010] By adopting the above technical solution, the designer can protect the upper connection position of the first connecting bolt by using the pressure-resistant outer cylinder, thereby protecting the connection position of the outer sleeve. This allows the outer sleeve to be fixed downwards under the impact of the pressure head. The trumpet-shaped pressure-resistant outer cylinder can increase the downward pressure surface and facilitate the subsequent erection of the inner sleeve. During construction, the second hydraulic clamp on the front side of the static pile driver can clamp and limit the movement.

[0011] Furthermore, the upper flange connection of the positioning tenon groove is provided with a pressure-resistant inner cylinder, the upper end of which is a trumpet-shaped tungsten carbide component, and the lower end of which has the same flange connection structure as the insertion end.

[0012] By adopting the above technical solution, when it is necessary to install internal pipelines, the pressure head force can be dispersed by the pressure-resistant inner cylinder, thereby effectively protecting the pressure-resistant inner cylinder. During construction, the first hydraulic clamp on the front side of the static pile driver can fix and limit the pressure-resistant inner cylinder.

[0013] Furthermore, a return spring is provided between the buffer and the rotating member, and one end of the buffer is inserted into the interior of the rotating member.

[0014] By adopting the above technical solution, when the first rotating rod and the second rotating rod are rotating and deforming, the buffer component moves upward in an arc shape. When the buffer component contacts the side of the outer sleeve, the buffer component compresses the return spring within a certain limit, so that the buffer component can eventually move to a suitable position to support the inside of the outer sleeve.

[0015] Furthermore, the connecting end includes a connecting piece disposed on the upper end of the inner sleeve. The connecting piece is a symmetrically descending sheet-like structure. The lower end of the insertion end is provided with connecting grooves at equal intervals. The connecting grooves are groove structures symmetrically provided with the connecting pieces. The sides of the connecting pieces are provided with corresponding sliding grooves according to their height. The inner side of the sliding groove is provided with a sliding bolt. The sliding bolt includes a sliding element, and the front side of the sliding element is threaded with an inner bolt.

[0016] By adopting the above technical solution, the connecting groove and connecting piece are arranged symmetrically and alternately. When the connecting groove and connecting piece are rotated, the connecting groove and connecting piece at different heights are inserted into each other. Thus, the flange connection height of the two inner sleeves can be adjusted by rotating the flange connection, while maintaining the connection stability between the two inner sleeves. When the two inner sleeves are separated, the sliding bolt will move up and down in the middle of the sliding groove.

[0017] Furthermore, the lower end of the inner sleeve is provided with several triangular positioning tenons at equal intervals, and the upper end of the inner sleeve is fixedly installed with several phase stakes corresponding to the positioning tenons at equal intervals.

[0018] By adopting the above technical solution, when multiple inner sleeves are connected to each other, they can be aligned and fixed by positioning tenons and phase stakes.

[0019] Furthermore, the upper end of the limiting mounting component is connected to the inner sleeve via a second connecting bolt, and the lower end of the insertion end is provided with a threaded groove corresponding to the second connecting bolt, depending on the height of the internal connecting groove.

[0020] By adopting the above technical solution, when the limiting mounting component is installed and fixed by rotating different connection positions, the limiting mounting component is set to different positions.

[0021] Furthermore, it includes the following steps; Step 1: Use drilling to determine the depth of the collapsed borehole and the water content of the soil layer, draw a geological profile, and determine the number of splicing sections of the outer and inner sleeves based on the extent of the collapsed borehole. Step 2: Assemble the static pile driver and adjust the clamping accuracy of the first and second hydraulic clamps; Step 3: Pre-assemble the outer sleeve: Insert the outer sleeve flange connecting piece into the insertion slot of the adjacent outer sleeve, and use the first connecting bolt to fix the plug-in buckle to the outer sleeve flange connecting slot.

[0022] Inner sleeve pre-connection: Align with the phase pile through the positioning tenon, insert the connecting piece into the connecting groove, and rotate the adjusting sliding bolt to the design height; Step 4: Using a total station for positioning, place the first outer sleeve vertically at the borehole opening with the pressure-resistant outer sleeve facing upwards. Start the static pile driver and use the second hydraulic clamp to hold the outer sleeve and press it down at a speed of 0.5 to 1 m / min. The pressure-resistant outer sleeve disperses the impact force of the soil layer. After installing the outer and inner sleeves in step 5, a layer of sand can be injected between the inner and outer sleeves, and then concrete can be injected into the inside of the inner sleeve. Step 6: After the concrete has initially set, a crane can be used to lift the outer sleeve and the inner sleeve in sequence. When the inner sleeve is lifted, the first and second rotating rods inside will bend and retract, and the cement mortar inside will overflow from the connection point, filling the space and forming a cement protrusion in the sand space, thus completing the construction.

[0023] Compared with the prior art, the advantages of this invention are: 1. In this invention, by providing a mudguard groove, when installing outer sleeves of different sizes, the tilt angle of the first rotating rod and the second rotating rod can be controlled by rotating the installation angle of the two insertion ends. Thus, when installing the inner sleeve, there can be stable support at the connection position between the inner sleeve and the outer sleeve, effectively maintaining concentricity.

[0024] 2. In this invention, by providing a structure with a connecting end and an insertion end, when pulled upwards, the connection positions of the connecting ends and insertion ends of the two inner sleeves will generate corresponding spaces at the mudguard groove position according to the insertion depth of different connecting grooves and connecting pieces. The first rotating rod and the second rotating rod will synchronously retract to form a space, and the cement mortar inside the inner sleeve will flow into the space and solidify into a square concrete structure, which can increase the stability of the cement column after molding. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is an overall structural diagram of the outer sleeve of the present invention; Figure 3 This is a schematic diagram of the inner sleeve structure of the present invention; Figure 4 This is a structural schematic diagram showing the location of the connecting piece in this invention; Figure 5 For the present invention Figure 5 A schematic diagram of the structure in section A; Figure 6 This is a schematic diagram of the insertion slot of the present invention; Figure 7 This is a schematic diagram of the internal bolt of the present invention.

[0026] The following are the labeling instructions in the diagram: 1. Pressure head; 2. First hydraulic clamp; 3. Second hydraulic clamp; 4. Outer sleeve; 401. Insertion buckle; 402. Insertion groove; 5. Static pile driver; 6. First connecting bolt; 7. Pressure-resistant outer cylinder; 8. Pressure-resistant inner cylinder; 9. Inner sleeve; 901. Positioning tenon; 902. Phase pile; 10. Connecting end; 1001. Connecting piece; 1002. Sliding groove; 11. Insertion end; 1101. Connecting groove; 12. Outer cylinder flange connecting groove; 13. Outer cylinder flange connecting piece; 14. Reinforcing member; 15. First rotating rod; 16. Second rotating rod; 17. Limiting installation member; 18. Second connecting bolt; 19. Mudguard groove; 20. Rotating member; 21. Return spring; 22. Buffer member; 23. Sliding bolt; 2301. Inner bolt; 2302. Sliding member. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] like Figure 1 - Figure 7 As shown, the embodiment of the present invention provides: including an outer sleeve 4, an outer sleeve flange connecting piece 13 is provided at the upper end of the outer sleeve 4, an insertion groove 402 corresponding to the outer sleeve flange connecting piece 13 is provided at the lower end of the outer sleeve 4, an inner sleeve 9 is provided in the middle of the outer sleeve 4, a connecting end 10 is provided at the upper end of the inner sleeve 9, and an insertion end 11 is provided at the lower end of the inner sleeve 9. Multiple inner sleeves 9 can be spliced ​​together. The upper flange of the uppermost inner sleeve 9 is provided with a positioning tenon 901. The upper end of the positioning tenon 901 is provided with a connecting end 10. A pair of stabilizing devices are symmetrically arranged on the upper side of the inner sleeve 9. The stabilizing device includes a reinforcing member 14 fixedly installed on the top of the inner sleeve 9. A first rotating rod 15 is rotatably mounted on the upper end of the reinforcing member 14. A second rotating rod 16 is rotatably mounted on the upper end of the first rotating rod 15. A limit mounting member 17 is rotatably mounted on the upper end of the second rotating rod 16. A mud-blocking groove 19 is fixedly mounted on the outer side of the second rotating rod 16. A rotating member 20 is rotatably mounted on the side of the mud-blocking groove 19. An arc-shaped mud-blocking plate for guiding cement slurry is provided. A rotating support arm is hinged to the side wall of the rotating member 20. A buffer member 22 is slidably mounted on the side of the rotating member 20. The lower end of the outer sleeve 4 is provided with several plug-in buckles 401 at equal intervals. The upper end of the outer sleeve 4 is provided with an outer sleeve flange connection groove 12 corresponding to the plug-in buckles 401. The lower side of the outer sleeve 4 is provided with several plug-in buckles 401 at equal intervals. The side of the outer sleeve flange connection piece 13 is provided with a circular groove corresponding to the plug-in buckles 401. Multiple outer sleeves 4 are fixedly connected by the first connecting bolt 6. Multiple outer sleeves 4 can be flange connected to each other. The outer sleeve flange connection piece 13 at the upper end of the outer sleeve 4 can be inserted into the insertion groove 402 at the bottom of another outer sleeve 4 on the upper side. Then, the two outer sleeves 4 can be fixed by the outer sleeve 4. The outer sleeves 4 can be interlocked to provide support for the outer side of the inner wall of the foundation pit. The upper end of the top outer sleeve 4 is provided with a pressure-resistant outer sleeve 7. The pressure-resistant outer sleeve 7 is connected to the upper flange of the outer sleeve 4. The lower end of the pressure-resistant outer sleeve 7 is provided with the same plug-in buckle 401 as the lower end of the outer sleeve 4. The pressure-resistant outer sleeve 7 and the outer sleeve 4 are fixedly connected by the first connecting bolt 6. The pressure-resistant outer sleeve 7 is a flared component made of tungsten carbide alloy (WC-Co). The pressure-resistant outer sleeve 7 can protect the upper connection position of the first connecting bolt 6, thereby protecting the connection position of the outer sleeve 4. This allows the outer sleeve 4 to be fixed downward under the impact of the pressure head 1. The flared pressure-resistant outer sleeve 7 can increase the downward pressure surface and facilitate the subsequent erection of the inner sleeve 9. During construction, the second hydraulic clamp 3 on the front side of the static pile driver 5 can clamp and limit the movement. The upper flange connection of the positioning tenon groove 901 is provided with a pressure-resistant inner cylinder 8. The upper end of the pressure-resistant inner cylinder 8 is a trumpet-shaped tungsten carbide component, and the lower end of the pressure-resistant inner cylinder 8 is provided with a flange connection structure identical to that of the insertion end 11. When it is necessary to install internal pipes, the pressure of the pressure head 1 can be dispersed through the pressure-resistant inner cylinder 8, thereby effectively protecting the pressure-resistant inner cylinder 8. During construction, the first hydraulic clamp 2 on the front side of the static pile driver 5 can fix and limit the pressure-resistant inner cylinder 8. A return spring 21 is fixedly installed between the buffer member 22 and the rotating member 20. One end of the return spring 21 is fixedly connected to the rotating member 20, and the other end is fixedly connected to the buffer member 22. One end of the buffer member 22 is inserted into the interior of the rotating member 20. When the first rotating rod 15 and the second rotating rod 16 are rotating and deforming, the buffer member 22 moves upward in an arc shape. When the buffer member 22 contacts the side of the outer sleeve 4, the buffer member 22 compresses the return spring 21 within a certain limit, so that the buffer member 22 can finally move to a suitable position to support the interior of the outer sleeve 4. The connecting end 10 includes a connecting piece 1001 disposed on the upper end of the inner sleeve 9. The connecting piece 1001 is a symmetrically descending plate structure. The lower end of the insertion end 11 has equidistant connecting grooves 1101, which are symmetrically formed with the connecting piece 1001. The sides of the connecting piece 1001 are provided with corresponding sliding grooves 1002 according to their height. A sliding bolt 23 is disposed inside the sliding groove 1002. The sliding bolt 23 includes a sliding element 2302. The front thread is provided with an inner bolt 2301. The connecting groove 1101 and the connecting piece 1001 are arranged alternately and symmetrically. When the connecting groove 1101 and the connecting piece 1001 are rotated, the connecting groove 1101 and the connecting piece 1001 at different heights are inserted into contact. Thus, the flange connection height of the two inner sleeves 9 can be adjusted by rotating the flange connection, while maintaining the connection stability between the two inner sleeves 9. When the two inner sleeves 9 are separated, the sliding bolt 23 will move up and down in the middle of the sliding groove 1002. The lower end of the inner sleeve 9 is provided with several triangular positioning tenons 901 at equal intervals, and the upper end of the inner sleeve 9 is fixedly installed with several phase stakes 902 corresponding to the positioning tenons 901 at equal intervals. When multiple inner sleeves 9 are connected to each other, they can be aligned and fixed by the positioning tenons 901 and the phase stakes 902. The upper end of the limiting mounting part 17 is connected to the inner sleeve 9 by the second connecting bolt 18. The lower end of the insertion end 11 is provided with a threaded groove corresponding to the second connecting bolt 18 according to the different heights of the internal connecting groove 1101. When the limiting mounting part 17 is installed and fixed by rotating different connection positions, the limiting mounting part 17 is set to different positions. Step 1: Use drilling to determine the depth of the collapsed borehole (usually ≤5m) and the soil moisture content, draw a geological profile, and determine the number of splicing sections of the outer sleeve 4 and the inner sleeve 9 based on the extent of the collapsed borehole. Step 2: Assemble the static pile driver 5 and adjust the clamping accuracy of the first hydraulic clamp 2 and the second hydraulic clamp 3; Step 3: Pre-assemble the outer sleeve 4: Insert the outer sleeve flange connecting piece 13 into the insertion groove 402 of the adjacent outer sleeve 4, and use the first connecting bolt 6 to fix the plug-in buckle 401 to the outer sleeve flange connecting groove 12.

[0029] Inner sleeve pre-connection: Align the positioning tenon 901 with the phase pile 902, insert the connecting piece 1001 into the connecting groove 1101, and rotate the adjusting sliding bolt 23 to the design height; Step 4: Using a total station for positioning, the first outer sleeve 4 is placed vertically at the borehole opening with the pressure-resistant outer sleeve 7 facing upwards. The static pile driver 5 is started, and the outer sleeve 4 is clamped by the second hydraulic clamp 3 and pressed down at a speed of 0.5 to 1 m / min. The pressure-resistant outer sleeve 7 disperses the impact force of the soil layer. After installing the outer sleeve 4 and the inner sleeve 9 in step 5, a layer of sand can be injected between the inner sleeve 9 and the outer sleeve 4, and then concrete can be injected into the inside of the inner sleeve 9. Step 6: After the concrete has initially set, a crane can be used to lift the outer sleeve 4 and the inner sleeve 9 in sequence. When the inner sleeve 9 is lifted, the first rotating rod 15 and the second rotating rod 16 inside it bend and retract, and the cement mortar inside will overflow from the connection position, filling the space and forming a cement protrusion in the sand space, thus completing the construction.

[0030] The working principle of this invention is as follows: The operator can pre-assemble two outer sleeves 4 and an inner sleeve 9. A positioning tenon 901 is fixedly installed on the upper side of the top inner sleeve 9 using a first connecting bolt 6. A total station and pressure head 1 are used for positioning and pre-embedding of the assembled inner sleeve 9. Then, the excavation device can be switched to excavate the soil from the middle of the inner sleeve 9. When pre-embedding pipes of level three or higher, the upper pressure-resistant outer sleeve component 7 of the outer sleeve 4 can be removed. Then, the required outer sleeve 4 is installed on the upper end of the outer sleeve 4. The pressure-resistant outer sleeve component 7 is installed on the upper end of the newly installed outer sleeve 4 using bolts, thus continuing the pre-embedding of the outer sleeve 4. After the outer sleeve 4 is pre-embedded and the internal soil layer is excavated, the two inner sleeves 9 are pre-assembled. The operator can then... The splicing angle of the two inner sleeves 9 is adjusted by rotating the inner sleeve 4 according to the internal pipe diameter. The connecting end 10 includes a connecting piece 1001 set on the upper end of the inner sleeve 9. The connecting piece 1001 is a symmetrically descending plate structure. The lower end of the insertion end 11 is provided with connecting grooves 1101 at equal intervals. The connecting grooves 1101 are groove structures symmetrically provided with the connecting piece 1001. The sides of the connecting piece 1001 are provided with corresponding sliding grooves 1002 according to their height. The inner side of the sliding groove 1002 is provided with a sliding bolt 23. The sliding bolt 23 includes a sliding element 2302. The front side of the sliding element 2302 is threaded with an inner bolt 2301. The connecting grooves 1101 and the connecting piece 1001 are arranged symmetrically and alternately. When the connecting grooves 1101 and the connecting piece 1001 rotate... During setup, the connecting grooves 1101 and connecting pieces 1001 at different heights are inserted into each other, allowing the flange connection height of the two inner sleeves 9 to be adjusted via a rotating flange connection. This also maintains a stable connection between the two inner sleeves 9. When the two inner sleeves 9 separate, the sliding bolt 23 moves up and down in the middle of the sliding groove 1002. A total station can be used to position the inner sleeves 9. Since the connecting piece 1001 has three symmetrical heights, the longest connecting piece 1001 has three sliding grooves 1002, with the next few sliding grooves decreasing in size. By adjusting the unfolding angles of the first rotating rod 15 and the second rotating rod 16, the inner diameter of the outer sleeve 4 is accommodated. Then, the inner bolt 2301 and sliding piece 2302 are used to connect the two inner sleeves. The inner sleeves 9 are fixed in place so that when the two inner sleeves 9 are joined, the angle at which the first rotating rod 15 and the second rotating rod 16 extend outwards is equal to the diameter of the outer sleeve 4. Simultaneously, when the two inner sleeves 9 are separated, the first rotating rod 15 and the second rotating rod 16 remain vertical. When the inner sleeve 9 is inserted into the outer sleeve 4, if the lower inner sleeve 9 does not touch the bottom of the pit, the first rotating rod 15 and the second rotating rod 16 are vertical, and the mud-blocking groove 19 faces downwards. When the inner sleeve 9 touches the ground, the first rotating rod 15 and the second rotating rod 16 are forced to rotate outwards, the mud-blocking groove 19 expands outwards, and the buffer 22 gradually forms an arc shape, contacting the interior of the outer sleeve 4. This keeps the inner sleeve 9 in the middle position of the outer sleeve 4. After the inner sleeve 9 is pre-embedded...A layer of sand can be filled between the inner sleeve 9 and the outer sleeve 4. After the sand is filled, concrete mortar can be injected into the inner sleeve 9. When the mortar begins to solidify, the operator can use a crane to lift the outer sleeve 4 upwards, completely detaching it. Then, the crane can lift the inner sleeve 9 upwards. During the lifting process, the separation of the inner sleeve 9 will cause the first rotating rod 15 and the second rotating rod 16 to return to a vertical position. During this return process, the original voids in the sand layer will be exposed. The high pressure of the concrete mortar will cause it to flow outwards into the exposed voids in the sand layer, forming a square concrete structure. This increases the stability of the cement column after molding. The mud-blocking groove 19 will not generate excessive resistance to the upward lifting of the inner sleeve 9. At the same time, when the inner sleeve 9 is completely lifted, the concrete will fuse with the square concrete structure.

[0031] 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 preferred examples and are not intended to limit 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 claimed invention.

Claims

1. A double-casing structure for shallow, easily collapsible geological formations, comprising an outer casing (4), characterized in that: The upper end of the outer sleeve (4) is provided with an outer sleeve flange connecting piece (13), the lower end of the outer sleeve (4) is provided with an insertion groove (402) corresponding to the outer sleeve flange connecting piece (13), the middle part of the outer sleeve (4) is provided with an inner sleeve (9), the upper end of the inner sleeve (9) is provided with a connecting end (10), and the lower end of the inner sleeve (9) is provided with an insertion end (11). Multiple inner sleeves (9) can be spliced ​​together. The upper flange of the uppermost inner sleeve (9) is provided with a positioning tenon (901). The upper end of the positioning tenon (901) is provided with a connecting end (10). A pair of stabilizing devices are symmetrically arranged on the upper side of the inner sleeve (9). The stabilizing device includes a reinforcing member (14) fixedly installed on the top of the inner sleeve (9). A first rotating rod (15) is rotatably provided on the upper end of the reinforcing member (14). A second rotating rod (16) is rotatably provided on the upper end of the first rotating rod (15). A limit mounting member (17) is rotatably provided on the upper end of the second rotating rod (16). A mudguard groove (19) is fixedly installed on the outer side of the second rotating rod (16). A rotating member (20) is rotatably provided on the side of the mudguard groove (19). A buffer member (22) is slidably provided on the side of the rotating member (20).

2. The double-casing structure for shallow, easily collapsible geological formations according to claim 1, characterized in that: The lower end of the outer sleeve (4) is provided with several plug-in buckles (401) at equal intervals. The upper end of the outer sleeve (4) is provided with an outer sleeve flange connection groove (12) corresponding to the plug-in buckles (401). The lower side of the outer sleeve (4) is provided with several plug-in buckles (401) at equal intervals. The side of the outer sleeve flange connection piece (13) is provided with a circular groove corresponding to the plug-in buckles (401). The multiple outer sleeves (4) are fixedly connected by a first connecting bolt (6).

3. The double-casing structure for shallow, easily collapsible geology according to claim 1, characterized in that: The outer sleeves (4) can be inserted into each other to provide support for the outer side of the pit inner wall. The upper end of the top outer sleeve (4) is provided with a pressure-resistant outer sleeve (7). The pressure-resistant outer sleeve (7) is connected to the upper flange of the outer sleeve (4). The lower end of the pressure-resistant outer sleeve (7) is provided with the same insertion buckle (401) as the lower end of the outer sleeve (4). The pressure-resistant outer sleeve (7) and the outer sleeve (4) are fixedly connected by the first connecting bolt (6). The pressure-resistant outer sleeve (7) is a flared component made of tungsten carbide alloy (WC-Co).

4. The double-casing structure for shallow, easily collapsible geological formations according to claim 1, characterized in that: The upper flange of the positioning tenon (901) is provided with a pressure-resistant inner cylinder (8). The upper end of the pressure-resistant inner cylinder (8) is a trumpet-shaped tungsten carbide component, and the lower end of the pressure-resistant inner cylinder (8) is provided with a flange connection structure that is the same as that of the insertion end (11).

5. A double-casing structure for shallow, easily collapsible geology according to claim 1, characterized in that: A return spring (21) is provided between the buffer (22) and the rotating member (20), and one end of the buffer (22) is inserted into the interior of the rotating member (20).

6. The double-casing structure for shallow, easily collapsible geological formations according to claim 1, characterized in that: The connecting end (10) includes a connecting piece (1001) disposed on the upper end of the inner sleeve (9). The connecting piece (1001) is a symmetrically descending sheet structure. The lower end of the insertion end (11) is provided with connecting grooves (1101) at equal intervals. The connecting grooves (1101) are groove structures symmetrically provided with the connecting piece (1001). The side of the connecting piece (1001) is provided with corresponding sliding grooves (1002) according to its height. The inner side of the sliding groove (1002) is provided with a sliding bolt (23). The sliding bolt (23) includes a sliding element (2302). The front thread of the sliding element (2302) is provided with an inner bolt (2301).

7. A double-casing structure for shallow, easily collapsible geological formations according to claim 1, characterized in that: The lower end of the inner sleeve (9) is provided with several triangular positioning tenons (901) at equal intervals, and the upper end of the inner sleeve (9) is fixedly installed with several phase stakes (902) corresponding to the positioning tenons (901).

8. A double-casing structure for shallow, easily collapsible geology according to claim 1, characterized in that: The upper end of the limiting installation part (17) is connected to the inner sleeve (9) by the second connecting bolt (18), and the lower end of the insertion end (11) is provided with a threaded groove corresponding to the second connecting bolt (18) according to the different heights of the internal connecting groove (1101).

9. A method for constructing a double-casing structure in shallow, easily collapsible geological formations, relating to the double-casing structure described in any one of claims 1-8, characterized in that... Including the following step; Step 1: Use drilling to determine the depth of the collapsed hole (usually ≤5m) and the water content of the soil layer, draw a geological profile, and determine the number of splicing sections of the outer sleeve (4) and the inner sleeve (9) according to the extent of the collapsed hole. Step 2: Assemble the static pile driver (5) and adjust the clamping accuracy of the first hydraulic clamp (2) and the second hydraulic clamp (3); Step 3: Pre-assemble the outer sleeve (4): Insert the outer sleeve flange connecting piece (13) into the insertion groove (402) of the adjacent outer sleeve (4), and fix the plug buckle (401) and the outer sleeve flange connecting groove (12) with the first connecting bolt (6).

10. Pre-connection of inner sleeve (9): Align the positioning tenon (901) with the phase pile (902), insert the connecting piece (1001) into the connecting groove (1101), and rotate the adjusting sliding bolt (23) to the design height; Step 4: Using a total station for positioning, place the first outer sleeve (4) vertically at the borehole opening with the pressure-resistant outer sleeve (7) facing upwards. Start the static pile driver (5) and clamp the outer sleeve (4) with the second hydraulic clamp (3) and press down at a speed of 0.5 to 1 m / min. The pressure-resistant outer sleeve (7) disperses the impact force of the soil layer. After installing the outer sleeve (4) and inner sleeve (9) in step 5, a layer of sand can be injected between the inner sleeve (9) and the outer sleeve (4), and then concrete can be injected into the inside of the inner sleeve (9). Step 6 After the concrete has initially set, a crane can be used to lift the outer sleeve (4) and the inner sleeve (9) in sequence. When the inner sleeve (9) is lifted, the first rotating rod (15) and the second rotating rod (16) inside it bend and retract, and the cement mortar inside will overflow from the connection position, filling the space and forming a cement protrusion in the sand space, thus completing the construction.

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