Composite bamboo joint drainage pile and construction method thereof

Abstract

The invention discloses a composite bamboo joint drainage pile and a construction method thereof. The composite bamboo joint drainage pile comprises a pile body of a prefabricated bamboo joint pile, a pile shoe is fixed to the bottom end of the pile body, a plurality of grooves are formed in bamboo joints of the pile body, each groove vertically penetrates through all the bamboo joints of the pile body, and a plastic drainage belt is vertically arranged in each groove. The upper end of each plastic drainage belt is used for being connected with an earth surface vacuum drainage system, the lower end of each plastic drainage belt is communicated with the annular drainage coil, and the bottom of each plastic drainage belt and the annular drainage coil are fixed to the bottom end of the pile body through the pile shoe. The composite bamboo joint drainage pile structure with bearing and vertical drainage consolidation functions can be formed, and a combined action channel of pile end annular drainage consolidation and pile side vertical drainage consolidation is constructed, so that the pile end resistance and the pile side resistance of the bamboo joint pile are improved at the same time. The composite bamboo joint drainage pile and the construction method thereof are wide in application range and particularly suitable for reinforcement and treatment engineering of high-compressibility foundations in soft soil and coastal areas and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soft soil foundation treatment and pile foundation engineering, and particularly relates to a composite bamboo joint drainage pile and a construction method thereof. BACKGROUND

[0002] Engineering construction in coastal areas is very active. Pile foundation is one of the common soft soil foundation treatment methods in coastal areas and is the main bearing structure of various buildings and structures. However, the soft soil layer in the coastal area often has the characteristics of large thickness, high water content, poor permeability, high compressibility and low strength, and under the action of external load, it is easy to produce excessive settlement or uneven settlement, which seriously affects the bearing capacity of the pile foundation and the safety of the engineering structure. In order to accelerate the consolidation of soft soil, shorten the construction period and improve the bearing capacity of the pile foundation, a drainage pile technology system of collaborative application of “pile foundation” and “drainage consolidation” has been gradually formed in engineering.

[0003] The so-called “drainage pile” is a composite reinforcement method that accelerates the dissipation of pore water pressure to promote the strength growth of the soil around the pile by means of the collaborative layout of bearing piles and vertical drainage bodies in soft soil foundation. The typical implementation methods mainly include the following two types: (1) Separate scheme: pile foundation and vertical drainage well (mainly refers to plastic drainage belt, referred to as vertical well) are separately drilled in soft soil foundation, and there is a certain distance between the pile and the vertical well. The pile bears the load, and the vertical well accelerates the consolidation of the soft soil foundation; (2) Integrated scheme: the vertical well and the pile body are closely combined (such as binding, embedding or depending on the pile body groove / pile end member), and the vertical drainage channel is buried synchronously in the pile forming or pile sinking process, which shortens the radial drainage path, accelerates the consolidation of the soil around the pile, and improves the bearing capacity of the pile foundation. The construction process of the separate scheme is relatively independent, but it is complex and the construction period is long; the integrated scheme has obvious advantages in construction period, but it puts forward higher requirements for the reliable connection and protection of the plastic drainage belt. Especially in the high compressibility soil layer such as coastal reclamation area and silt soil, ensuring the continuity and stability of the drainage channel is the key link for the drainage pile technology to play its role.

[0004] At present, the plastic drainage belt (PVD) commonly used in engineering is composed of a core skeleton (board core) and a filter coating layer (filter membrane). The plastic drainage belt is buried in soft soil to form a vertical drainage channel and is connected with a surface vacuum unit or a horizontal drainage system. Under the action of preloading or vacuum negative pressure, the pore water in the soil is discharged through the drainage belt, thereby significantly shortening the consolidation time and improving the strength of the soft soil foundation. In the "pile-drainage" cooperative system, whether the spatial position of the drainage belt is accurate, whether the connection with the pile body is firm, and whether the drainage belt can remain in place / detach during the drainage consolidation process directly affects the effectiveness of the drainage pile technology. However, the existing technology still has deficiencies in the combination of the drainage belt and the pile body: the connection relies mainly on simple binding or external components, and the stability is poor; construction disturbance easily causes the displacement or damage of the drainage belt; and the long-term service is also prone to failure due to shearing, corrosion or pulling. In addition, the existing drainage pile technology only considers the drainage consolidation of the soil around the pile, thereby improving the side friction of the pile, but the effect of improving the bearing capacity of the pile is limited. In fact, according to the principles of soil mechanics and foundation engineering, the end resistance of the precast pile has a great influence on the bearing capacity of the pile. If the drainage consolidation of the soil around the pile is coupled with the drainage consolidation of the soil at the end of the pile, the synchronous drainage consolidation of the soil around the pile and the soil at the end of the pile will further improve the bearing capacity of the pile foundation in coastal areas. In view of this, the present application provides a composite bamboo joint drainage pile and a construction method thereof. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a composite bamboo joint drainage pile and a construction method thereof to overcome the deficiencies of the prior art, form a composite bamboo joint drainage pile structure with bearing and vertical drainage consolidation functions, construct a combined channel for the ring drainage consolidation at the end of the pile and the vertical drainage consolidation around the pile, and simultaneously improve the end resistance and side resistance of the bamboo joint pile, which is particularly suitable for reinforcement and treatment engineering of soft soil and high compressibility foundation in coastal areas.

[0006] The technical solution adopted by the present application to solve the above technical problem is: a composite bamboo joint drainage pile, comprising a pile body of a precast bamboo joint pile, a pile shoe fixed at the bottom end of the pile body, a plurality of grooves arranged at the bamboo joints of the pile body, each groove vertically penetrating all the bamboo joints of the pile body, a plastic drainage belt vertically arranged in each groove, the upper end of each plastic drainage belt being used for connecting a surface vacuum drainage system, the lower end of each plastic drainage belt being communicated with a ring-shaped drainage coil, and the bottom of each plastic drainage belt and the ring-shaped drainage coil being fixed to the bottom end of the pile body through the pile shoe.

[0007] The present application sets grooves at the bamboo joints of the pile body of the bamboo joint pile, arranges plastic drainage belts in the grooves, connects ring-shaped drainage coils at the lower end of the plastic drainage belts, and fixes the bottom of each plastic drainage belt and the ring-shaped drainage coil to the bottom end of the pile body through the pile shoe, so that the pile body has both bearing and drainage consolidation functions.

[0008] The bamboo joint structure of the composite bamboo joint drainage pile of the present application forms strong mechanical bite force and end bearing force in the foundation soil body, which can significantly improve the compression resistance and uplift resistance of the pile body; the groove provides a reliable protection space for the plastic drainage belt, effectively avoiding damage to the plastic drainage belt caused by pile sinking construction, and ensuring the verticality and continuity of the drainage channel. The plastic drainage belt forms a vertical drainage channel, which is connected with the annular drainage coil at the pile end to form a vertical-toroidal composite drainage channel at the pile end and the pile side, thereby realizing toroidal confluence and vertical drainage of pore water, accelerating the pressure dissipation of soil pore water, promoting the consolidation of soil around the pile, and simultaneously improving the pile end resistance and pile side resistance.

[0009] As a preferred, the pile shoe comprises a pile end plate and a plurality of angle steels, the pile end plate and the plurality of angle steels are fixed to the bottom end of the pile body by a plurality of anchor fasteners, the horizontal part of each of the angle steels is located on the lower side of the pile end plate, the vertical part of each of the angle steels is located on the radial outer side of the bottom of the pile body, the bottom of each of the plastic drainage belts is vertically clamped between the vertical part of one of the angle steels and the pile body, and the annular drainage coil is horizontally clamped between the pile end plate and the horizontal parts of the plurality of angle steels. The vertical part of the angle steel and the pile body form a clamping channel for the bottom of the plastic drainage belt, which is used for the introduction and fixation of the plastic drainage belt, and the structure is simple, which can reduce the repeated operation of "inserting the plate first and then piling" or "piling first and then binding", shorten the construction period and reduce the construction investment, in addition, the anchor fasteners form a stable and reliable connection between the pile end plate, the angle steels and the bottom end of the pile body, which can effectively avoid the damage to the bottom of the plastic drainage belt during the pile sinking construction.

[0010] As a preferred, the bottom end of the pile body is provided with a plurality of reserved holes, the pile end plate is provided with a plurality of butt joints, and the horizontal part of each of the angle steels is provided with a mounting hole, the plurality of anchor fasteners are a plurality of expansion bolts, and each of the expansion bolts is inserted into one of the reserved holes through one of the mounting holes and one of the butt joints and is expanded and locked. The expansion bolt is used as the anchor fastener to fix the pile shoe and the pile body, and to reliably clamp the plastic drainage belt and the annular drainage coil, which is simple in construction operation and good in effect.

[0011] As a preferred, each of the mounting holes is an oblong hole to compensate for the construction error.

[0012] As a preferred, the inner side of the vertical part of each of the angle steels is provided with anti-slip tooth patterns to enhance the clamping reliability of the plastic drainage belt.

[0013] As a preferred, the pile end plate is an annular plate, and the outer peripheral surface of the pile end plate is flush with the outer peripheral surface of the pile body, so as to increase the clamping area of the plastic drainage belt and achieve a more stable clamping effect.

[0014] As preferred, the radial outer side of the pile body is bound with several turns of binding belts, each of the turns of the binding belts is sleeved at one of the bamboo joints of the pile body, and the several turns of the binding belts are used for limiting and fixing the several plastic drainage belts, so that the plastic drainage belts are prevented from being displaced during construction and drainage consolidation.

[0015] As preferred, the diameter of the pile body is 300-500 mm, the diameter of the bamboo joint is 350-550 mm, the length of the pile body is 10-30 m, and the groove width of each of the grooves is 80-120 mm. The diameter of the pile body, the diameter of the bamboo joint and the length of the pile body are determined according to the engineering requirements.

[0016] The construction method of the composite bamboo joint drainage pile has the following steps. S1, pile sinking: vertically sinking the composite bamboo joint drainage pile into the foundation soil; S2, connecting the drainage system: connecting the upper end of each of the plastic drainage belts with the surface vacuum drainage system through the surface drainage pipeline; S3, vacuum preloading drainage: starting the surface vacuum drainage system, using the vacuum preloading method, gradually applying negative pressure to the foundation soil through the several plastic drainage belts to drain the pore water of the soil body, and monitoring the negative pressure, drainage flow and pore water pressure in real time until the foundation consolidation and settlement meet the design requirements; S4, sealing and finishing: removing the surface drainage pipeline, and sealing the upper end of each of the plastic drainage belts with sealing tape.

[0017] The advantages of the construction method of the present application mainly include: 1) high efficiency: through the "integrated construction", the pile body bearing and the drainage system construction are completed at the same time, avoiding the traditional two processes, reducing the construction links and period; 2) low disturbance: the integrated pile sinking method reduces the entry and exit of mechanical equipment, reduces the disturbance to the foundation soil, and is especially suitable for soft soil foundation; 3) high quality: the plastic drainage belt is embedded in the groove, ensuring accurate installation position and reducing the risk of damage or distortion on the construction site; 4) high bearing capacity: the pile end and pile side drainage consolidation are synchronized, improving the bearing capacity of the pile foundation and composite foundation.

[0018] As preferred, the pile body is prefabricated by high-strength concrete through centrifugal casting.

[0019] Compared with the prior art, the present application has the following advantages: 1. The application can realize the combination of two aspects: one is to combine the bamboo joint pile with the plastic drainage belt by opening a groove at the bamboo joint, forming a composite bamboo joint drainage pile structure with bearing and vertical drainage consolidation functions; the other is to construct a combined channel of pile end ring drainage consolidation and pile side vertical drainage consolidation, thereby improving the pile end resistance and pile side resistance of the bamboo joint pile at the same time. 2. The construction method can realize integrated construction, and has simple steps and high construction effect. The method can complete the introduction and end anchoring of the plastic drainage belt simultaneously in the pile sinking process, can shorten the total construction period of foundation treatment and pile foundation engineering, and avoid the defects of easy loosening and inaccurate positioning of traditional binding or buckle mode, thereby ensuring the continuity of the drainage channel. 3. The composite bamboo joint drainage pile and the construction method thereof have wide application range, and are particularly suitable for reinforcement and treatment engineering of soft soil and high compressibility foundation in coastal areas. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a longitudinal section view of the effect after the construction of the composite bamboo joint drainage pile in embodiment 1. Figure 2 is Figure 1 is an enlarged view of A in the middle. Figure 3 is a structure schematic view of the pile end after the construction of the composite bamboo joint drainage pile in embodiment 1. Figure 4 is an appearance schematic view of the angle steel in embodiment 1. Figures 1-4 In the specific drawing marks, the following are included: 1-pile body, 11-bamboo joint, 12-reserved hole, 2-pile shoe, 21-pile end plate, 22-angle steel, 23-horizontal part, 24-vertical part, 25-anti-skid tooth pattern, 26-butting hole, 27-mounting hole, 3-plastic drainage belt, 4-ring drainage coil, 5-expansion bolt, 6-surface vacuum drainage system, 61-surface drainage pipeline, 7-ground soil body. DETAILED DESCRIPTION

[0021] The application will be further described in detail in combination with the embodiments of the drawings.

[0022] Example 1: A composite bamboo-joint drainage pile includes a prefabricated bamboo-joint pile body 1 with a diameter of 300-500 mm, a bamboo joint diameter of 350-550 mm, and a pile length of 10-30 m. A pile shoe 2 is fixed to the bottom end of the pile body 1. Two grooves are provided at the bamboo joints 11 of the pile body 1, each groove being 80-120 mm wide. Each groove vertically penetrates all the bamboo joints 11 of the pile body 1. A plastic drainage strip 3 with a width of 80-120 mm and a thickness of 4-6 mm is vertically arranged in each groove. The plastic drainage strip 3 is tightly fitted to the groove. The upper end of each plastic drainage strip 3 is used to connect to the surface vacuum drainage system 6, and the lower end of each plastic drainage strip 3 is connected to the annular drainage coil 4. The bottom of each plastic drainage strip 3 and the annular drainage coil 4 are both fixed to the bottom end of the pile body 1 by the pile shoe 2. In this embodiment, the annular drainage coil 4 is made of polypropylene (PP) or polyester (PET), has a circular cross-section, and a cross-sectional diameter of 4-6 mm.

[0023] In Example 1, the pile shoe 2 includes a pile end plate 21 and two angle steels 22. Both the pile end plate 21 and the two angle steels 22 are fixed to the bottom end of the pile body 1 by two anchors. The pile end plate 21 is an annular plate, and its outer circumferential surface is flush with the outer circumferential surface of the pile body 1. The horizontal portion 23 of each angle steel 22 is located below the pile end plate 21, and the vertical portion 24 of each angle steel 22 is located radially outward from the bottom of the pile body 1. The inner surface of the vertical portion 24 of each angle steel 22 is provided with anti-slip teeth 25. The bottom of each plastic drainage strip 3... The vertical part 24 of an angle steel 22 is clamped between the vertical part 24 and the pile body 1. The annular drainage coil 4 is clamped horizontally between the pile end plate 21 and the horizontal part 23 of the two angle steels 22. Specifically, the bottom end of the pile body 1 is provided with several reserved holes 12, the pile end plate 21 is provided with several docking holes 26, and the horizontal part 23 of each angle steel 22 is provided with an installation hole 27. The two anchors are two expansion bolts 5. Each expansion bolt 5 passes through an installation hole 27 and a docking hole 26 and extends into a reserved hole 12 to expand and lock.

[0024] In a further optimized implementation scheme, several loops of binding tape can be tied to the radial outer side of the pile body 1, with each loop of binding tape fitted onto a section 11 of the pile body 1. The loops of binding tape are used to limit and fix several plastic drainage belts 3. Each mounting hole 27 can be an elongated hole. The main body of the pile shoe 2 can be made of stainless steel or corrosion-resistant alloy steel and treated with anti-corrosion. Wedges or pressure strips can be added in the trench to increase the clamping force on the plastic drainage belts 3.

[0025] Example 2: A construction method for the composite bamboo-joint drainage pile of Example 1, comprising the following steps: S1, pile sinking: the pile body 1 is obtained by high-strength concrete through centrifugal casting, then the plastic drainage belt 3, pile shoe 2 and annular drainage coil 4 and other components are assembled on the pile body 1 to obtain a composite bamboo joint drainage pile; according to the design drawing, the pile position is accurately discharged, and the position is marked by using a total station or GNSS positioning; then the composite bamboo joint drainage pile is vertically sunk into the foundation soil by using a static pile machine, a hammer pile machine or a vibrating pile machine; S2, connecting the drainage system: the upper end of each plastic drainage belt 3 is connected with the ground vacuum drainage system 6 through the ground drainage pipeline 61; S3, vacuum preloading drainage: the ground vacuum drainage system 6 is started, and the vacuum preloading method is used to gradually apply negative pressure to the foundation soil through the two plastic drainage belts 3 to drain the pore water of the soil body, and the changes of negative pressure, drainage flow and pore water pressure are monitored in real time until the consolidation and settlement of the foundation reach the design requirements; S4, sealing and finishing: the ground drainage pipeline is removed, and the upper end of each plastic drainage belt 3 is sealed with sealing tape to complete the construction of the current composite bamboo joint drainage pile.

[0026] After the construction of the above-mentioned composite bamboo joint drainage pile, the bamboo joint structure forms strong mechanical gripping force and end bearing force in the foundation soil 7, which can significantly improve the compression and uplift resistance of the pile body; the groove provides a reliable protection space for the plastic drainage belt 3, effectively avoiding damage to the plastic drainage belt 3 caused by pile sinking construction, and ensuring the perpendicularity and continuity of the drainage channel. The plastic drainage belt 3 forms a vertical drainage channel, which is connected with the annular drainage coil 4 at the pile end to form a vertical-circumferential composite drainage channel at the pile end and the pile side, thereby realizing the circumferential convergence and vertical drainage of pore water, accelerating the pressure dissipation of soil pore water, promoting the consolidation of soil around the pile, and simultaneously improving the pile end resistance and pile side resistance.

Claims

1. A composite bamboo-joint drainage pile, characterized in that, The pile body includes a precast bamboo-joint pile, with a pile shoe fixed to the bottom end of the pile body. Several grooves are provided at the bamboo joints of the pile body. Each groove vertically penetrates all the bamboo joints of the pile body. A plastic drainage strip is vertically arranged in each groove. The upper end of each plastic drainage strip is used to connect to a surface vacuum drainage system. The lower end of each plastic drainage strip is connected to an annular drainage coil. The bottom of each plastic drainage strip and the annular drainage coil are both fixed to the bottom end of the pile body by the pile shoe.

2. The composite bamboo-joint drainage pile according to claim 1, characterized in that, The pile shoe includes a pile end plate and several angle steels. The pile end plate and several angle steels are fixed to the bottom end of the pile body by several anchors. The horizontal part of each angle steel is located below the pile end plate, and the vertical part of each angle steel is located radially outside the bottom of the pile body. The bottom of each plastic drainage strip is vertically sandwiched between the vertical part of an angle steel and the pile body. The annular drainage coil is horizontally sandwiched between the pile end plate and the horizontal part of the several angle steels.

3. The composite bamboo-joint drainage pile according to claim 2, characterized in that, The bottom end of the pile body is provided with several reserved holes, the pile end plate is provided with several docking holes, each of the angle steels is provided with an installation hole on its horizontal part, and the several anchors are several expansion bolts. Each expansion bolt passes through an installation hole and a docking hole and extends into a reserved hole to expand and lock.

4. The composite bamboo-joint drainage pile according to claim 3, characterized in that, Each of the mounting holes is an oblong hole.

5. The composite bamboo-joint drainage pile according to claim 2, characterized in that, The inner surface of the vertical part of each angle steel piece is provided with anti-slip serrations.

6. The composite bamboo-joint drainage pile according to claim 2, characterized in that, The pile end plate is an annular plate, and the outer circumferential surface of the pile end plate is flush with the outer circumferential surface of the pile body.

7. The composite bamboo-joint drainage pile according to claim 1, characterized in that, The pile body is bound with several loops of binding tape on its radial outer side. Each loop of binding tape is fitted onto a section of the pile body. The loops of binding tape are used to limit and fix several plastic drainage belts.

8. A composite bamboo-joint drainage pile according to claim 1, characterized in that, The diameter of the pile body is 300-500 mm, the diameter of the bamboo joint is 350-550 mm, the pile length is 10-30 m, and the width of each trench is 80-120 mm.

9. A construction method for a composite bamboo-joint drainage pile according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Pile driving: Vertically drive composite bamboo-joint drainage piles into the foundation soil; S2. Connecting to the drainage system: Connect the upper end of each of the plastic drainage strips to the surface vacuum drainage system through a surface drainage pipe; S3. Vacuum preloading drainage: Start the surface vacuum drainage system and use the vacuum preloading method to gradually apply negative pressure to the foundation soil through several plastic drainage strips to drain the pore water in the soil. Monitor the negative pressure, drainage flow rate and pore water pressure changes in real time until the foundation consolidation and settlement meet the design requirements. S4. Sealing and finishing: Remove the surface drainage pipes and then seal the upper end of each plastic drainage strip with sealing tape.

10. The construction method of the composite bamboo-joint drainage pile according to claim 9, characterized in that, The pile body is prefabricated from high-strength concrete using a centrifugal casting method.

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