Gravel pile forming structure and method suitable for soft soil foundation

Abstract

The invention belongs to the technical field of pile forming structures, and particularly relates to a gravel pile forming structure and method suitable for a soft soil foundation. The sleeve is arranged on the lower portion of the pile pipe in a sleeved mode, sliding grooves are formed along the circumference of the sleeve at equal intervals, the anti-loosening bolts penetrate through the sliding grooves to be fixed to the pile pipe, and the hinge is arranged on the pile pipe through the pin shaft. By means of the collaborative design of the pile pipe, the sleeve, the sliding groove, the check bolt and the hinge, soft soil can be effectively prevented from invading the hole wall, the problems that in soft soil foundation construction, necking and pile breaking of a pile foundation are likely to happen, gravel is difficult to come out of the pipe, and the compactness of a pile body is insufficient are fundamentally solved, the pile forming quality of the immersed tube compaction gravel pile is remarkably improved, and the construction period is shortened. The pile body structure is stable and reliable.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of pile-forming structure, and particularly relates to a gravel pile-forming structure and method suitable for soft soil foundation. BACKGROUND

[0002] In the construction of water conservancy and hydropower projects, the treatment of soft soil foundation is a key link of foundation and foundation engineering. Soft soil foundation has the characteristics of low strength, high compressibility and poor water permeability. If not properly treated, it is easy to cause problems such as foundation settlement and insufficient bearing capacity. At present, the treatment methods of soft soil foundation mainly include replacement cushion method, preloading method, rolling and tamping method, vibration compaction method, gravel pile method, CFG pile method, cement mixing pile method and the like. Among them, the gravel pile method is a flexible pile body formed by using gravel (gravel, sand and gravel, etc.) as the main material. It has the advantages of simple construction technology, easy quality guarantee, remarkable effect of soft soil foundation reinforcement, low engineering cost, and the soil between piles can be drained and consolidated through the pile body, and the post-strength of the composite foundation can be continuously increased. It is widely used in engineering.

[0003] However, when the gravel pile is applied to the construction of soft soil foundation, due to the extremely low strength of soft soil, the unbalanced stress of the soil body on the hole wall can easily lead to insufficient stability, and further cause the phenomenon of soft soil intrusion into the hole wall. This problem will directly cause the necking of the pile foundation, the breaking of the pile, the insufficient density of the gravel pile body and other defects, which seriously affects the quality and reliability of the foundation treatment. In addition, the intrusion of soft soil will also cause the difficulty of gravel out of the pipe, increase the construction difficulty, reduce the pile-forming efficiency, and even need to be reworked, further increasing the engineering cost.

[0004] Therefore, how to solve the problems of necking and breaking of the gravel pile, insufficient density and low construction efficiency in the construction of soft soil foundation has become a technical difficulty to be improved in the field. There is a lack of a gravel pile-forming structure with simple structure, low cost and effective adaptation to the characteristics of soft soil foundation in the prior art, and a new technical scheme is urgently needed to improve the pile-forming quality and construction efficiency. SUMMARY

[0005] The purpose of the present application is to provide a gravel pile-forming structure and method suitable for soft soil foundation to solve the problems in the background art.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a gravel pile-forming structure suitable for soft soil foundation, comprising a pile pipe, a sleeve, a sliding groove, a locking bolt and a loose leaf; the sleeve is sleeved on the lower part of the pile pipe, the sliding groove is equidistantly arranged along the circumference of the sleeve, the locking bolt passes through the sliding groove and is fixed on the pile pipe, and the loose leaf is arranged on the pile pipe through a pin shaft.

[0007] Preferably, the inner diameter of the sleeve is 4-6mm larger than the outer diameter of the pile pipe, and the steel material with the same wall thickness and the same quality as the pile pipe is used for manufacturing.

[0008] Preferably, the number of the sliding grooves is not less than 3, and the direction of the sliding grooves is consistent with the direction of the sleeve.

[0009] Preferably, the height of the sliding groove is consistent with the height of the reverse insertion of the pile tube; the distance from the lower end of the sliding groove to the bottom of the sleeve is equal to the distance from the anti-loose bolt to the bottom of the pile tube.

[0010] Preferably, the diameter of the anti-loose bolt is slightly smaller than the diameter of the sliding groove, and the height of the anti-loose bolt exceeds the sleeve by a certain height.

[0011] Preferably, the diameter of the loose-leaf unfolding is slightly smaller than the inner diameter of the pile tube.

[0012] A method for forming a gravel pile in a soft soil foundation by using the structure, comprising the following steps: (1) Vibration sinking: the pile tube and the sleeve are synchronously vibrated and sunk under the constraint of the anti-loose bolt until reaching the designed foundation bottom, at which time the loose-leaf is in a closed state; (2) Feeding: the gravel is loaded into the pile tube, and the loose-leaf is kept closed to temporarily store the gravel; (3) Lifting: the pile tube is lifted upward while vibrating, the loose-leaf is opened under the action of the self-weight of the gravel and the vibration, the gravel flows out of the pile tube, and the sleeve is kept in place to block the soft soil from invading by being extruded by the soft soil; when the anti-loose bolt moves to the top of the sliding groove, the sleeve is synchronously lifted until the distance from the bottom of the sleeve to the designed pile bottom is equal to the single pile forming height; (4) Reverse insertion: the pile tube moves downward, the loose-leaf is closed, and the gravel is extruded by vibration to compact the pile body and expand the pile diameter; (5) Repeating steps (2)-(4) until the whole pile construction is completed.

[0013] Preferably, the vibration sinking frequency in step (1) is adapted to the compactness of the soft soil foundation to ensure the vertical sinking of the pile tube.

[0014] Preferably, the lifting speed of the pile tube in step (3) is 0.5-1.5 m / min, and the continuous vibration is kept during the lifting process.

[0015] Preferably, the reverse insertion depth in step (4) is 1 / 2-2 / 3 of the lifting height of the pile tube, and the vibration frequency during the reverse insertion is increased by 10%-20% compared with that in the lifting stage.

[0016] The present application has the beneficial effects that: through the cooperative design of the pile tube, the sleeve, the sliding groove, the anti-loose bolt and the loose-leaf, the present application can effectively block the soft soil from invading the hole wall, fundamentally solves the problems of pile necking, broken pile, difficulty in gravel outflow and insufficient compactness of the pile body in the soft soil foundation construction, significantly improves the pile forming quality of the pipe sinking extruded gravel pile, and ensures the stable and reliable structure of the pile body.

[0017] Meanwhile, the structure is simple in design, each component is made of conventional steel material and is simple in connection mode, thereby reducing manufacturing cost and simplifying construction process. Through relative sliding of the sleeve and the pile pipe, opening and closing of the hinge, the gravel filling and compaction process is efficient and orderly, thereby greatly improving pile construction efficiency and meeting the actual needs of soft soil foundation treatment in water conservancy and hydropower engineering. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a structural diagram of the present application; Figure 2 is an exploded view of the present application; Figure 3 is a working state schematic diagram of the present application; Figure 4 is a schematic diagram of the sleeve in the lower part of the present application; Figure 5 is a schematic diagram of the sleeve in the lifting state of the present application. DETAILED DESCRIPTION

[0019] In the description of the present disclosure, it needs to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present disclosure.

[0020] The terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present disclosure, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0021] In the description of the present disclosure, it needs to be explained that, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrally connected, it can be mechanically connected, or it can be electrically connected, or it can be communicatively connected, it can be directly connected, or it can be indirectly connected through an intermediate medium, it can be the communication or interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present disclosure can be understood according to the specific circumstances.

[0022] The specific embodiments of the present application will be described in detail below in combination with the drawings and preferred embodiments.

[0023] As Figures 1-4 shown, a gravel pile forming structure suitable for soft soil foundation includes a pile pipe 1, a sleeve 2, a sliding groove 3, a locking bolt 4 and a hinge 5. The pile pipe 1 is the core component of the pile forming structure, made of steel material, and the lower part of its outer side is sleeved with the sleeve 2. The sleeve 2 and the pile pipe 1 are made of steel material with the same wall thickness and the same quality, and the inner diameter of the sleeve 2 is 4-6mm larger than the outer diameter of the pile pipe 1, so as to ensure that there is a relative sliding gap between the two. Along the circumferential direction of the sleeve 2, not less than 3 sliding grooves 3 are processed at equal intervals, and the extension direction of the sliding groove 3 is consistent with the length direction of the sleeve 2 (i.e. the vertical direction); the height of the sliding groove 3 is consistent with the sinking height during the reverse insertion operation of the pile pipe 1, and the distance L1 from the lowermost end of the sliding groove 3 to the bottom of the sleeve 2 is equal to the distance L2 from the locking bolt 4 to the bottom of the pile pipe 1, so as to ensure that the sliding stroke of the sleeve 2 matches the operation rhythm of the pile pipe 1.

[0024] The locking bolt 4 is vertically fixed on the outer side wall of the pile pipe 1 after passing through the sliding groove 3 on the sleeve 2, and its diameter is slightly smaller than that of the sliding groove 3, so that the sleeve 2 can freely slide up and down along the pile pipe 1 under the joint constraint of the locking bolt 4 and the sliding groove 3; at the same time, the top of the locking bolt 4 exceeds the outer surface of the sleeve 2 by a certain height, so as to prevent the sleeve 2 from being pulled out of the sliding groove 3 during the sliding process. The hinge 5 is hinged to the inner side wall of the pile pipe 1 through a pin shaft, and the maximum diameter of the hinge 5 in the unfolded state is slightly smaller than the inner diameter of the pile pipe 1, so that the hinge 5 can be flexibly opened and closed around the pin shaft, and when closed, it can block the bottom of the pile pipe 1 to prevent gravel from leaking out in advance, and when opened, it allows gravel to flow out smoothly.

[0025] Construction process Vibration sinking stage: the pile pipe 1 and the sleeve 2 sink synchronously under the driving of the locking bolt 4 until reaching the designed foundation bottom; at this time, the hinge 5 is in the closed state, and the pile pipe 1 extrudes the surrounding soil during the sinking process to form a pile space.

[0026] Material feeding stage: gravel is loaded into the pipe through the feeding port of the pile pipe 1, and during this period, the hinge 5 remains closed to ensure that the gravel is temporarily stored in the pile pipe 1.

[0027] Lifting stage: after the pile tube 1 is filled with the gravel, it is lifted upwards while vibrating; during the lifting process, the hinge 5 is opened under the action of the self-weight of the gravel and the vibration, the gravel flows out of the pile tube 1 and enters the cavity below the pile tube 1; during this process, the sleeve 2 remains in the original position and continuously blocks the soft soil from invading the hole wall due to the gap between the sleeve 2 and the pile tube 1 and the extrusion of the surrounding soft soil; when the pile tube 1 is lifted to the position where the locking bolt 4 moves to the top of the chute 3, the sleeve 2 is synchronously moved upwards by the locking bolt 4 until the height from the bottom of the sleeve 2 to the designed pile bottom is equal to the designed pile height each time, and then the pile tube 1 stops being lifted.

[0028] Reverse insertion stage: the pile tube 1 starts to move downwards, and the hinge 5 is closed at this time; the pile tube 1 extrudes the gravel in the cavity, and the gravel is compacted under the action of the vibration, and at the same time, the pile diameter is expanded under the extrusion, and the pile body of this section is completed.

[0029] The above steps of feeding, lifting and reverse insertion are repeated until the whole pile construction is completed.

[0030] It should be pointed out that, for those skilled in the art, a number of improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as falling within the scope of the present application.

Claims

1. A gravel pile structure suitable for soft soil foundation, characterized in that: The invention comprises a pile pipe (1), a sleeve (2), a chute (3), an anti-loosening bolt (4) and a loose-leaf (5); the sleeve (2) is sleeved on the lower part of the pile pipe (1), and the chute (3) is equidistantly provided along the circumference of the sleeve (2); the anti-loosening bolt (4) passes through the chute (3) and is fixed on the pile pipe (1); and the loose-leaf (5) is arranged on the inner wall (6) of the pile pipe (1) through a pin shaft.

2. The gravel pile structure suitable for soft soil foundation according to claim 1, characterized in that: The inner diameter of the sleeve (2) is 4-6 mm larger than the outer diameter of the pile pipe (1), and is made of steel with the same wall thickness and quality as the pile pipe.

3. The gravel pile structure suitable for soft soil foundation according to claim 1, characterized in that: The number of the slide grooves (3) is not less than 3, and the direction of the slide grooves (3) is consistent with the direction of the sleeve (2).

4. The gravel pile structure suitable for soft soil foundation according to claim 1, characterized in that: The height of the chute (3) is consistent with the height of the reverse insertion of the pile pipe (1); the distance L1 between the lower end of the chute (3) and the bottom of the sleeve (2) is equal to the distance L2 between the anti-loosening bolt (4) and the bottom of the pile pipe (1).

5. The gravel pile structure suitable for soft soil foundation according to claim 1, characterized in that: The diameter of the anti-loosening bolt (4) is slightly smaller than the diameter of the slide groove (3), and the height of the anti-loosening bolt (4) exceeds the height of the sleeve (2) by a certain height.

6. The gravel pile structure suitable for soft soil foundation according to claim 1, characterized in that: The unfolded diameter of the loose leaf (5) is slightly smaller than the inner diameter of the pile pipe (1).

7. A method for constructing gravel piles on soft soil foundation using the structure according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) Vibration sinking: The pile pipe and sleeve sink synchronously under the constraint of anti-loosening bolts until they reach the bottom of the designed foundation, at which time the loose-leaf is in a closed state; (2) Feeding: Load crushed stone into the pile tube, and keep the loose-leaf closed to temporarily store the crushed stone; (3) Lifting: The pile pipe is lifted upward while vibrating. The loose-leaf opens under the action of the gravel's own weight and vibration, and the gravel flows out of the pile pipe. The sleeve is squeezed by the soft soil and remains in place to prevent the soft soil from invading. When the anti-loosening bolt moves to the top of the chute, it drives the sleeve to be lifted synchronously until the height of the sleeve bottom from the designed pile bottom is equal to the single pile height. (4) Reverse insertion: The pile tube moves downward, the hinge closes, and the gravel is squeezed by vibration to compact the pile body and expand the pile diameter; (5) Repeat steps (2) to (4) until the entire pile construction is completed.

8. The method according to claim 7, characterized in that The frequency of the vibration sinking in step (1) is adapted to the density of the soft soil foundation to ensure that the pile pipe sinks vertically.

9. The method according to claim 7, characterized in that In step (3), the pile pipe is lifted at a speed of 0.5-1.5 m / min, and continuous vibration is maintained during the lifting process.

10. The method according to claim 7, characterized in that In step (4), the reverse insertion depth is 1 / 2-2 / 3 of the pile pipe lifting height, and the vibration frequency during reverse insertion is increased by 10%-20% compared with the lifting stage.

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