Cast-in-place pile structure with sleeve

Abstract

The utility model relates to the technical field of cast-in-place piles, discloses a cast-in-place pile structure with a sleeve, and aims at solving the technical problems that a traditional cast-in-place pile is insufficient in bearing capacity, low in side wall friction resistance and poor in long-term stability in a peat soil layer. The cast-in-place pile structure comprises a cylindrical pile body, and the pile body sequentially penetrates through a soil filling layer, a surface soil layer and a peat soil layer from the ground and then extends to the bottom of a clay layer. And a sleeve is fixedly sleeved on the peaty soil layer section of the pile body. The sleeve inhibits lateral deformation of the pile body through annular constraint, the concrete compressive strength and the pile-soil interface friction resistance are improved, and the pile length requirement is reduced. Through layered reinforcement design, sleeve constraint is specifically applied to a soft soil layer section, compared with a traditional full-pile-section steel reinforcement framework or steel casing scheme, steel can be saved, the pile length can be shortened, the comprehensive manufacturing cost can be reduced, meanwhile, the advantages of efficient bearing and economical efficiency are achieved, and the structure is suitable for complex stratum pile foundation engineering.

Description

TECHNICAL FIELD

[0001] The utility model relates to a cast-in-place pile technical field, especially in a cast-in-place pile structure with sleeve. BACKGROUND

[0002] Bored cast-in-place pile is widely used in bridge, building and other engineering fields due to its flexible adjustment of pile diameter and length, no noise pollution, excellent bearing performance and other characteristics. It forms a pile body through mechanical hole forming, reinforcement cage hoisting and concrete pouring, which can effectively disperse the upper structure load and control the foundation settlement. However, when applied in complex strata (such as areas containing peat soil layer), the traditional cast-in-place pile technology still has the following technical bottlenecks:

[0003] 1. Insufficient bearing capacity of soft soil layer: peat soil layer has the characteristics of high water content, low strength and high compressibility, and the pile body is prone to lateral deformation when passing through this layer, resulting in reduced compressive strength of the pile body, which requires increasing the pile length or configuring dense reinforcement cages to meet the bearing requirements, significantly increasing the engineering cost.

[0004] 2. Limited side wall friction: traditional cast-in-place pile relies on the friction of pile-soil interface to transfer load, but the loose structure of peat soil layer leads to insufficient side wall friction, which requires additional setting of stirrups or expanding the pile diameter, significantly increasing the construction complexity and material consumption.

[0005] 3. Pile body stability risk: in soft soil layer, the pile body is easily affected by soil creep, pore water pressure change and other factors, resulting in long-term bearing capacity decline, even causing pile body cracking or settlement overrun and other problems.

[0006] The existing technology mainly uses full-pile-section reinforcement cage or steel casing full-coating process to solve the above problems, but it has the defects of serious material waste, low construction efficiency and poor economy. Therefore, there is an urgent need for a cast-in-place pile structure that can specifically strengthen the performance of soft soil layer section of the pile body and balance the bearing efficiency and economy. INVENTION CONTENTS

[0007] The utility model aims at solving the above technical problem, and proposes a cast-in-place pile structure with sleeve, which applies circumferential constraint to the pile body by setting a sleeve in the peat soil layer section, improves the compressive strength and side wall friction of the pile body, and optimizes the structural design to reduce the engineering cost.

[0008] The technical scheme adopted by the utility model is as follows:

[0009] A cast-in-place pile structure with sleeve, the cast-in-place pile structure with sleeve comprises a pile body in a cylindrical structure; the top of the pile body is exposed to the ground, and the bottom extends to the clay layer after passing through the fill layer, topsoil layer and peat soil layer in turn; a sleeve in a cylindrical structure is fixedly sleeved on the pile body, and the sleeve is located in the peat soil layer.

[0010] Further, the bottom of the pile body is formed with a reinforcing body, the reinforcing body is located in the clay layer, is fixedly connected with the pile body, and the diameter of the reinforcing body is greater than that of the pile body.

[0011] Further, the top of the pile body is provided with a top cover, the top cover is fixedly connected with the pile body, and the top cover is provided with a plurality of grouting through holes which are the same as the inside of the pile body.

[0012] The pile body has the advantages that:

[0013] The sleeve bored pile structure provided by the utility model realizes the following remarkable technical effects through innovative design:

[0014] 1. Strengthen the compression resistance of the pile body and the side wall friction: the sleeve is arranged in the peat soil layer section, the lateral deformation of the pile body is inhibited through the annular constraint, and the compression strength of the concrete is improved; meanwhile, the sleeve and the soil form a composite interface, the side wall friction is increased, the length of the pile can be reduced compared with the traditional process, and the material and construction costs are reduced.

[0015] 2. Optimize the bearing mechanism of the soft soil layer: the sleeve isolates the pile body from the peat soil, avoids the adverse effects of soil creep and pore water pressure fluctuation on the pile body, and improves the long-term bearing stability; in cooperation with the bottom reinforcing body, the load is transmitted to the stable clay layer through the reinforcing body, forming a cooperative bearing system of upper constraint and lower anchoring.

[0016] 3. Simplify the construction process and reduce the cost: the longitudinal reinforcement and the stirrup of the traditional steel reinforcement cage are cancelled, the sleeve is used to replace the shear resistance function, and the amount of steel is reduced; the top cover integrates the grouting through hole, the uniform pouring of the concrete in the gap between the pile body and the sleeve is realized, the construction efficiency is improved, and the risk of hole blockage is avoided.

[0017] 4. Environmental adaptability and economy are prominent: the sleeve is only applied to the soft soil layer section, and the steel material is saved compared with the whole pile section steel casing scheme; the reinforcing body adopts the enlarged head anchoring, adapts to different geological conditions, reduces the comprehensive cost, and has environmental protection and economic benefits.

[0018] The utility model cracks the technical problems that the traditional bored pile has insufficient bearing capacity in complex stratum and serious material waste through the layered strengthening design concept, and provides an efficient and economical solution for soft soil layer pile foundation engineering. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is the whole structure schematic view of the utility model sleeve bored pile structure;

[0020] In the drawing: 100, clay layer; 101, reinforcing body; 200, peat soil layer; 300, topsoil layer; 400, fill layer; 500, pile body; 600, sleeve; 700, top cover; 701, grouting through hole. DETAILED DESCRIPTION

[0021] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0022] To address the technical problems of insufficient bearing capacity, low sidewall friction, and poor long-term stability of traditional cast-in-place piles in peat soil layers, this embodiment provides a cast-in-place pile structure with a sleeve. For example... Figure 1 As shown, the sleeved cast-in-place pile structure includes a cylindrical pile body 500. The pile body 500 uses a precast steel cage with main reinforcement bars of Φ16-25mm, HRB400 grade. The main reinforcement bars are arranged along the axial direction of the pile body 500, eliminating traditional stirrups and retaining only longitudinal main reinforcement bars to save steel. The steel cage is formed into the pile body 500 by cast-in-place concrete. The top of the pile body 500 is exposed above the ground, and the bottom extends through the fill layer 400, the topsoil layer 300, and the peat soil layer 200 before reaching the clay layer 100.

[0023] like Figure 1 As shown, in this embodiment, a cylindrical sleeve 600 is fixedly fitted onto the pile body 500. Specifically, the sleeve 600 is a Q345B steel cylinder with a thickness of 8-12mm. The inner diameter of the sleeve 600 matches the outer diameter of the pile body 500, with a gap ≤5mm. The sleeve 600 is fixed to the reinforcing cage of the pile body 500 by welding, and as shown... Figure 1 As shown, it is necessary to ensure that the sleeve 600 is located in the peat soil layer 200. The function of the sleeve 600 is to suppress the lateral deformation of the pile 500 through circumferential restraint, thereby improving the compressive strength of the concrete; at the same time, the sleeve 600 forms a composite interface with the soil, increasing the side wall friction resistance, which can reduce the pile length and lower material and construction costs compared to traditional methods. In addition, the sleeve 600 can isolate the pile 500 from the peat soil, avoiding the adverse effects of soil creep and pore water pressure fluctuations on the pile 500, thus improving the bearing stability. By using the sleeve 600 to improve shear resistance, the number of longitudinal bars and stirrups in the pile 500 reinforcement cage can be reduced, thereby reducing the amount of steel used and saving steel.

[0024] Furthermore, such as Figure 1As shown, in this embodiment, a reinforcing body 101 is also arranged at the bottom of the pile body 500, which is located in the clay layer 100 and has an enlarged head shape, with a diameter of 1.5-2 times the diameter of the pile body 500. For example, when the diameter of the pile body 500 is 800 mm, the diameter of the reinforcing body 101 can be selected as 1200-1600 mm. The reinforcing body 101 is fixedly connected with the bottom of the pile body 500 by field pouring of high-strength concrete with a strength of C40 or more or pre-embedding implantation, to form a pile end bearing core. The reinforcing body 101 cooperates with the sleeve 600 and the pile body 500 to form a synergistic bearing system with upper restraint and lower anchoring. The reinforcing body 101 has an enlarged head shape, so that the load can be transmitted to the stable clay layer 100 through the reinforcing body 101, thereby adapting to different geological conditions.

[0025] In addition, considering the convenience of grouting of the pile body 500, the sleeve 600 is arranged on the pile body 500. Figure 1 As shown, in this embodiment, a top cover 700 is arranged at the top of the pile body 500, which is made of a 20-30 mm thick steel plate. The top cover 700 is welded after being anchored by a Φ16 mm HRB400 grade U-shaped steel rod pre-embedded at the top of the pile body 500, and full welding process is used at the welding position to ensure the sealing property. As shown, Figure 1 A plurality of grouting through holes 701 are arranged on the top cover 700, which are the same as the internal structure of the pile body 500, for concrete pouring and air exhaust of the pile body 500.

[0026] The construction process of the sleeve-equipped cast-in-place pile structure is as follows:

[0027] First, a rotary drilling rig is used to drill through the fill layer 400, the topsoil layer 300 and the peat soil layer 200 to the designed depth of the clay layer 100. The sleeve 600 is lowered in the peat soil layer 200 section, and is pressed into the soil layer by a static pressure device to ensure that the sleeve 600 closely fits the hole wall. An enlarged head hole is drilled at the bottom of the clay layer 100, and C40 concrete is poured to form the reinforcing body 101 after hole cleaning. Then, the reinforcement cage of the pile body 500 is inserted and vibrated to be compacted. Finally, C30 concrete is poured into the gap between the sleeve 600 and the hole wall, and then the concrete of the pile body 500 is continuously poured through the grouting through holes 701 of the top cover 700, to exhaust air and excess slurry. After pouring is completed, the top cover 700 and the concrete at the top of the pile body 500 are simultaneously maintained, to form an integrated sleeve-equipped cast-in-place pile structure.

[0028] The sleeve-equipped cast-in-place pile structure is sleeved on the pile body 500 by the sleeve 600, which can exert a circumferential restraint force on the pile body 500, increase the compressive strength of the material of the pile body 500 and the frictional resistance of the pile body side wall, so as to reduce the pile length. At the same time, the sleeve-equipped cast-in-place pile structure can fully utilize the bearing capacity of the soil between piles to jointly act, without the need to additionally arrange longitudinal reinforcement and hoop steel skeleton, and effectively reduce the pile length, thereby reducing the cost of the pile foundation.

[0029] The basic principle, main features and advantages of the present application are shown and described above. It should be understood by those skilled in the art that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A socketed cast-in-place pile structure, characterised in that: The sleeve bored pile structure comprises a pile body in a cylindrical structure; the top of the pile body is exposed to the ground, the bottom of the pile body extends to the clay layer after passing through the fill layer, the topsoil layer and the peat soil layer in sequence; a sleeve in a cylindrical structure is fixedly sleeved on the pile body, and the sleeve is located in the peat soil layer.

2. A socketed cast-in-place pile construction according to claim 1, characterised in that: The bottom of the pile body is formed with a reinforcing body, the reinforcing body is located in the clay layer, is fixedly connected with the pile body, and the diameter of the reinforcing body is greater than the diameter of the pile body.

3. A socketed cast-in-place pile construction according to claim 1, characterised in that: The top of the pile body is provided with a top cover, the top cover is fixedly connected with the pile body, and the top cover is provided with a plurality of grouting through holes which are the same as the inside of the pile body.

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