CN-122013761-A - Cement soil composite variable-diameter pile with spiral rib on inner core and construction method thereof

CN122013761ACN 122013761 ACN122013761 ACN 122013761ACN-122013761-A

Abstract

The invention discloses a cement-soil composite variable diameter pile with spiral ribs on an inner core and a construction method thereof, the composite pile comprises a peripheral cement-soil pile body and an inner core precast concrete pile, the inner core is a prestressed high-strength concrete pipe pile, and the outer wall of the inner core is axially provided with at least one continuous spiral rib. The peripheral cement soil pile body is formed by in-situ stirring cement soil, and the diameter of the pile body is set to be a variable diameter along the depth direction and comprises at least one expanding section with the diameter larger than that of the standard section. The inner core is implanted into the peripheral cement-soil pile body which is not initially set and is coaxial with the peripheral cement-soil pile body. The invention obviously enhances the mechanical engagement and side friction resistance of the inner core and the outer core through the spiral rib structure of the inner core, simultaneously the variable diameter design of the peripheral pile body can pointedly reinforce the soft soil layer, optimize the stress performance and the material consumption, and has the advantages of high bearing capacity, good pulling resistance, high construction efficiency, economy, environmental protection and the like.

Inventors

ZHU NAN
LIU AIMIN
LIU WENBIN
ZHUGE AIJUN
YU ZHIFA
ZHU YAOTING
WANG XUEKUI
ZHAO DONGHUI
CHEN JU

Assignees

中交天津港湾工程研究院有限公司
中交第一航务工程局有限公司
天津港湾工程质量检测中心有限公司

Dates

Publication Date: 20260512
Application Date: 20260327

Claims (9)

1. The cement soil composite reducing pile with the spiral rib on the inner core is characterized by comprising a peripheral cement soil pile body and an inner core precast concrete pile; The inner core precast concrete pile is a prestressed concrete pipe pile, and at least one continuously-protruding spiral rib is axially arranged on the outer wall of the inner core precast concrete pile; The peripheral cement soil pile body is a columnar body formed by in-situ stirring of cement soil, and the diameter of the pile body is set to be a variable diameter along the depth direction, and comprises at least one standard section and at least one diameter expansion section with the diameter larger than that of the standard section; The inner core precast concrete pile is coaxially implanted in the peripheral cement-soil pile body which is not initially set, and the spiral rib is embedded and meshed in the cement soil of the peripheral cement-soil pile body.
2. The cement-soil composite reducing pile with the spiral ribs on the inner core according to claim 1, wherein the cross section of each spiral rib is trapezoid, rectangular or semicircular, the height of each spiral rib is 10-50 mm, the width of each spiral rib is 20-80 mm, and the helix angle of each spiral rib is 15-45 degrees.
3. The cement-soil composite reducing pile with the spiral ribs on the inner core according to claim 1, wherein the inner core precast concrete pile is formed by connecting a plurality of sections of tubular piles through end plates and connecting pieces.
4. The cement-soil composite variable-diameter pile with the spiral ribs on the inner core of the pile according to claim 1, wherein the diameter-enlarging section is arranged at a depth position corresponding to a soft soil layer of a foundation, and the ratio D Expansion of /D Label (C) of the diameter D Expansion of of the diameter-enlarging section to the diameter D Label (C) of the standard section is 1.2-2.0.
5. The construction method of the cement-soil composite variable-diameter pile with the spiral rib on the inner core according to claim 1, which is characterized by comprising the following steps: s1, prefabricating an inner core, namely prefabricating a prestress high-strength concrete pipe pile section with spiral ribs in a factory; s2, pile position measurement and field leveling, namely determining pile positions and leveling construction sites; S3, constructing the peripheral cement-soil pile body, namely sinking, spraying and stirring the designed pile position by using a stirring drilling machine with a diameter-variable reaming function, and forming a diameter-variable peripheral cement-soil pile body without initial setting by controlling opening and closing of a wing-expanding mechanism of a drill bit to form a diameter-expanded section with an expanded diameter in a preset depth region of a weak soil layer; s4, inner core implantation preparation, namely immediately moving the static pile press to a pile position after the step S3 is completed, leveling and centering, and enabling a pressure pile point to coincide with the central axis of the peripheral cement soil pile body; S5, inner core implantation and connection, namely lifting the first section of precast tubular pile segment by a static pile machine before initial setting of cement soil in the peripheral cement soil pile body, vertically inserting the precast tubular pile segment into the peripheral cement soil pile body, and carrying out static pressure to a set depth; and S6, curing and molding, namely standing and curing, and forming the cement-soil composite variable-diameter pile with the spiral rib on the inner core after the peripheral cement-soil pile body is finally set and hardened.
6. The construction method of the cement soil composite variable diameter pile with the spiral rib on the inner core is characterized in that in the step S3, the stirring drilling machine comprises a drill rod and a variable diameter stirring drill bit arranged at the bottom end of the drill rod, the variable diameter stirring drill bit comprises at least two wing expanding cutters which can expand and contract or swing in the radial direction, and the expansion angle or the extension length of the wing expanding cutters is controlled in a hydraulic or mechanical mode so as to realize cutting and stirring of pile holes with different diameters.
7. The construction method of the cement-soil composite variable diameter pile with the spiral rib on the inner core according to claim 5, wherein in the step S5, when the static pressure pile machine is pressing the inner core precast concrete pile, the pile pressing force is monitored in real time, and the pile pressing force is maintained within a preset range by adjusting the static pressure speed, so that the deviation of the perpendicularity of the inner core is ensured to be less than 0.5%.
8. The construction method of the cement-soil composite variable diameter pile with the spiral ribs on the inner core is characterized in that cement slurry is formed by mixing, by weight, 100 parts of cement, 20-30 parts of fly ash, 5-10 parts of bentonite, 50-65 parts of water, 0.5-1.5 parts of a water reducing agent and 1-3 parts of an early strength agent.
9. The construction method of the cement soil composite variable diameter pile with the spiral rib on the inner core is characterized by further comprising the step S7 of pile cap and cushion layer construction after the step S6, namely, the step of chiseling off redundant parts to the designed elevation on the pile head of the composite pile, constructing a reinforced concrete pile cap, and then paving a mattress cushion layer and a concrete cushion layer on the pile top and the soil between the piles to form a commonly stressed composite foundation.

Description

Cement soil composite variable-diameter pile with spiral rib on inner core and construction method thereof Technical Field The invention relates to the technical field of foundation treatment and pile foundation construction of constructional engineering, in particular to a cement-soil composite variable-diameter pile with spiral ribs in an inner core, which is suitable for reinforcing a soft soil foundation, can remarkably improve bearing performance and has economic and environment-friendly characteristics, and a construction method thereof. Background Soft soil layers with larger thickness, such as silt, mucky soil, soft clay and the like, are widely distributed in coastal, river-along and inland lake deposition areas. The soft soil has the characteristics of high natural water content, large pore ratio, high compressibility, low shear strength, poor permeability and the like. Engineering construction such as highway, railway, port and dock, high-rise building, etc. is performed on the foundation, and the foundation must be reinforced to meet the requirements of bearing capacity and deformation control. Cement-soil mixing piles and prestressed high-strength concrete piles (PHC piles) are two common foundation treatment modes. The cement soil mixing pile forcedly mixes the soft soil and the curing agent in the deep part of the foundation by special mixing machinery, and the soft soil is hardened into a high-quality foundation with integrity, water stability and certain strength by utilizing the physical-chemical reaction between the curing agent and the soft soil. The method has the advantages that the construction is free of vibration, noise and pollution, the bearing capacity of the foundation can be effectively improved, the pile body strength is relatively low, the bearing capacity is limited, and the pile forming quality is greatly influenced by soil uniformity and construction operation. The PHC pipe pile has the advantages of high pile body strength, high bearing capacity, high construction speed, stable and reliable quality and the like, but the pile sinking in soft soil can generate a larger soil squeezing effect, thereby causing adverse effects on the surrounding environment, and the performance of high strength of the PHC pipe pile is often not fully exerted because the side friction resistance provided by soft soil around the pile is too low. In order to combine the advantages of both pile types and overcome the respective disadvantages, various forms of composite piles or composite piles have been developed in the prior art. For example, a construction method of a cement-soil mixing pile-embedded prestressed pipe pile composite foundation is disclosed in the published patent, wherein a composite pile is formed by embedding a prestressed pipe pile before the cement-soil mixing pile is initially set. The technology provides a construction channel and lateral constraint for the pipe pile by using the cement-soil mixing pile, and meanwhile, the pipe pile makes up the defect of low strength of the cement-soil mixing pile. However, the existing composite piles still have technical bottlenecks to be broken through. First, the performance of the inner and outer core bonding surfaces is critical. The traditional smooth surface pipe pile and the cement soil are mainly adhered by means of cementing force and interfacial friction force, and due to solidification and shrinkage of the cement soil, a tiny gap is formed between the cement soil and the smooth surface pipe pile, so that interfacial side friction resistance is insufficient, and under the action of vertical load, the pipe pile and the cement soil can slide relatively, and real cooperative work cannot be realized. Secondly, the stress of the pile body is not good in matching with geological conditions. Deep soft soil layers tend not to be uniform and there may be multiple layers of soft soil or layers of different properties. The pile body with the same diameter cannot locally strengthen the weakest soil layer, so that material waste or insufficient local bearing capacity is caused. Thirdly, the refinement and automation level of the construction process are to be improved, and particularly in terms of ensuring the perpendicularity of the inner core and the concentricity of the inner core and the outer core, the traditional mode relying on manpower and experience is difficult to ensure high-quality piling. Therefore, development of a novel composite pile and a construction method thereof, which can effectively enhance the interface binding force of the inner core and the outer core, realize the optimal matching of the pile body bearing capacity and the geological conditions, and have high construction precision and high efficiency, are needed. Disclosure of Invention The invention aims to solve the defects in the prior art and provides a cement soil composite variable-diameter pile with a spiral rib on an inner core and a construction method ther