CN110820732A - Cast-in-situ bored pile suitable for karst area with connectivity channel and pile forming method - Google Patents

Cast-in-situ bored pile suitable for karst area with connectivity channel and pile forming method Download PDF

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Publication number
CN110820732A
CN110820732A CN201911052550.7A CN201911052550A CN110820732A CN 110820732 A CN110820732 A CN 110820732A CN 201911052550 A CN201911052550 A CN 201911052550A CN 110820732 A CN110820732 A CN 110820732A
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China
Prior art keywords
pile
reinforcement cage
cladding
pressure
karst
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CN201911052550.7A
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Chinese (zh)
Inventor
梅国雄
陆志宇
张福友
甘霖
赵艳林
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Guangxi University
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Guangxi University
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Priority to CN201911052550.7A priority Critical patent/CN110820732A/en
Publication of CN110820732A publication Critical patent/CN110820732A/en
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    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D5/00Bulkheads, piles, or other structural elements specially adapted to foundation engineering
    • E02D5/22Piles
    • E02D5/34Concrete or concrete-like piles cast in position ; Apparatus for making same
    • E02D5/38Concrete or concrete-like piles cast in position ; Apparatus for making same making by use of mould-pipes or other moulds
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D27/00Foundations as substructures
    • E02D27/32Foundations for special purposes
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D5/00Bulkheads, piles, or other structural elements specially adapted to foundation engineering
    • E02D5/22Piles
    • E02D5/48Piles varying in construction along their length, i.e. along the body between head and shoe, e.g. made of different materials along their length
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D2300/00Materials
    • E02D2300/0004Synthetics
    • E02D2300/0018Cement used as binder
    • E02D2300/002Concrete
    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D2300/00Materials
    • E02D2300/0085Geotextiles

Abstract

The cast-in-situ bored pile comprises a pile body and a coating piece, wherein the pile body at least comprises a concrete pile body and a reinforcement cage, the coating piece is a composite geotextile with a closed bottom and an open top, the coating piece is coated outside the reinforcement cage before the pile body is formed, the coating piece is arranged in a surrounding manner by an annular iron wire and is lightly buckled on the reinforcement cage, concrete grout is injected into the reinforcement cage at high pressure, the high-pressure concrete grout pushes part of the coating piece to bulge towards the connectivity channel to form a branch-shaped structure like a branch fork, and the pile is formed after the grout is condensed and hardened; the diameter of the cladding is greater than the diameter of the reinforcement cage and the length of the cladding is greater than the length of the reinforcement cage. The cast-in-situ bored pile is provided with the coating piece to wrap the grout, so that the phenomena of grout leakage, diameter reduction and the like during the manufacture of the cast-in-situ bored pile in a karst area are avoided, the pile forming quality is effectively ensured, the integrity of the pile and the karst with a communication channel is improved, and the bearing capacity of the pile is greatly improved.

Description

Cast-in-situ bored pile suitable for karst area with connectivity channel and pile forming method
Technical Field
The invention relates to the field of constructional engineering, in particular to a cast-in-situ bored pile suitable for a karst area with a communication channel and a pile forming method.
Background
Karst is a general term for geological actions of water on soluble rocks such as carbonate rock, gypsum, rock salt and the like, mainly based on chemical erosion action and assisted by mechanical actions such as flowing water erosion, undermining, collapse and the like, and phenomena resulting from these actions. The karst area of China is mainly concentrated in the southwest area, the area of the karst area of the southwest area accounts for more than one third of the area of the whole southwest area, and the geological condition of the karst area is extremely complex. When infrastructure design and construction are carried out in a karst area, the design requirement is high, the construction difficulty is large, the period is long, construction accidents are easy to happen, and the design and construction cost is greatly increased. How to design and construct foundation engineering meeting the requirement of bearing capacity of buildings or structures in areas of karst areas is a difficult problem to be solved in the front of design and construction personnel.
Aiming at the complex engineering geological condition of a karst area, the common foundation engineering form at present adopts a pile foundation, and the common form of the pile foundation is a common manual hole digging cast-in-place pile, a mechanical hole drilling cast-in-place pile and the like.
The construction process of the manual hole digging cast-in-place pile is relatively simple, the technical requirement is not high, the construction cost is low, the hole forming quality can be checked, and the concrete pouring quality is guaranteed, but the manual hole digging cast-in-place pile has certain limitation, is only suitable for about 6m to 20m long, has higher requirements on safety, such as harmful gas, inflammable gas, air rarefied and the like, and has special requirements on electric leakage protection when the underground water level in the karst cave is higher and the underground water level is also required to be pumped and dug. When meeting the area with larger connectivity karst or the foundation engineering with higher requirement on the bearing capacity, the pile length of the manual hole digging sometimes cannot meet the design requirement.
The mechanical drilling bored concrete pile uses large-scale mechanical drilling, the construction cycle is short, the speed is fast, the process is mature, the process is relatively safe and reliable, the pile length of the method construction can reach more than 20m, but because the excavation of the bored concrete pile belongs to the hidden project, the quality standard is difficult to control, and because many karst caves are distributed in the karst area, and the distribution is uneven, the size is different, and many channels with connectivity are still provided, therefore, in the actual grouting construction process, if the construction is improper, the phenomena of slurry leakage, hole treading, hole shrinkage, pile hole deflection and the like easily exist, and if the karst area with complex geological conditions is met, the commonly used pile foundation can not meet the requirement of bearing capacity, and the effect of the pile foundation can not be exerted.
Disclosure of Invention
The invention aims to solve the technical problem that the existing cast-in-situ bored pile is inapplicable in a karst area, and provides the cast-in-situ bored pile suitable for the karst area with the connectivity channel and the pile forming method, which can not only avoid the phenomena of slurry leakage, diameter reduction and the like when the cast-in-situ bored pile is manufactured in the karst area with the connectivity channel, but also effectively ensure the pile forming quality of the cast-in-situ bored pile, improve the integrity of the pile and the karst with the connectivity channel and greatly improve the bearing capacity of the pile.
The technical scheme adopted by the invention for solving the technical problems is as follows:
the cast-in-situ bored pile suitable for the karst area with the connectivity channel comprises a pile body and a cladding piece, wherein the pile body is a reinforced concrete pile and at least comprises a concrete pile body and a reinforcement cage, the reinforcement cage is an elongated cage which is surrounded by longitudinal reinforcements and stirrups, and the reinforcement cage is used as a prefabricated reinforcement framework before the pile body is formed into the pile; the covering piece is a composite geotextile (elastic cloth bag) with a closed bottom and an open top, the covering piece covers the outside of a reinforcement cage before the pile body is formed, the covering piece is arranged in a surrounding manner through an annular iron wire and is lightly buckled on the reinforcement cage, concrete grout is injected into the reinforcement cage (corresponding to the preset position of a pile hole) at high pressure, the high-pressure concrete grout pushes part of the covering piece to bulge towards the position of the communication channel to form a branch-shaped structure in the form of a branch fork, and the pile is formed after the high-pressure concrete grout is condensed and hardened; the diameter of the cladding is greater than the diameter of the reinforcement cage and the length of the cladding is greater than the length of the reinforcement cage.
According to the scheme, when a communication channel or a karst cave exists at the bottom of a pile hole, a pile end assembly is additionally arranged at the bottom of the cladding part and used for preventing the bottom of the cladding part from being stretched downwards to break due to excessive vertical pressure; the pile end assembly is two circular steel plates, and a circular steel plate welds in steel reinforcement cage bottom, and outside the cladding piece was arranged in to a circular steel plate, the cladding piece is equidistant to open with circular steel plate has four round holes that supply the screw steel pipe to pass, and screw steel pipe both ends are tightened up the steel sheet to cliping the cladding piece with the nut (reach control cladding piece bottom and do not produce the deformation, make the pile body does not extend to the effect that the cladding piece destroyed downwards infinitely).
According to the scheme, the diameter of the cladding piece is larger than that of the reinforcement cage before the pile body is formed into a pile by more than 0.2 m.
According to the scheme, the length of the cladding piece is more than 2m greater than that of the reinforcement cage before the pile body is formed into the pile.
The invention also provides a pile forming method of the cast-in-situ bored pile suitable for the karst region with the communication channel, which comprises the following steps:
(1) firstly, sheathing the cladding member outside the reinforcement cage, and lightly buckling the cladding member outside the reinforcement cage by using an annular iron wire with a certain furling degree, wherein the furling degree of the annular iron wire is not only capable of ensuring that the cladding member does not fall off in the process of placing the reinforcement cage, but also capable of ensuring that the annular iron wire is broken off by the pressure of slurry in the process of high-pressure grouting;
(2) hoisting a reinforcement cage lightly buckled with a cladding member into a preset position (a position where a pile is formed in advance) of a pile hole by using a hoisting tool, wherein the hoisting tool does not move any more after the reinforcement cage reaches a specified position, so that the position of the reinforcement cage is ensured to be fixed;
(3) pumping concrete with certain solidification time into the reinforcement cage directly or through a PPR pipe positioned in the middle of the reinforcement cage, adding an early-setting agent into the concrete according to specific construction requirements, then injecting concrete grout under high pressure, and filling and plugging the cladding member into a passage in a karst area with connectivity under the action of grouting pressure;
(4) the injection of the high-pressure concrete grout increases the pressure of the cladding part, the cladding part expands and breaks loose the annular iron wire, the expanded cladding part stops volume expansion when contacting the side wall of the drilled hole, the cladding part is attached to the side wall to form a cylinder, when the side wall is drilled in a karst region with a communication channel or a karst cave, the high-pressure concrete grout pushes the part of the cladding part to bulge towards the channel to form a dendritic body structure in a branch shape, the dendritic body structure is restrained by the pressure of the concrete grout and the cladding part at the same time, the pressure borne by the dendritic body structure is equal to the restraining force provided by the cladding part when the part bulges to a certain degree, at the moment, the dendritic body structure stops expansion, and a pile is formed after the high-pressure concrete grout is solidified and hardened.
According to the scheme, in the step (1), the annular iron wire manufacturing method includes the steps that an iron wire with the diameter of about 4mm is wound around a circle along the outer portion of the cladding piece and is slightly folded, and the cladding piece is folded outside the reinforcement cage through the annular iron wire, so that the cladding piece is prevented from touching the hole wall and being damaged in the subsequent lowering process.
Compared with the prior art, the invention has the following beneficial effects:
1. the cast-in-situ bored pile is provided with a coating part, namely composite geotextile coating slurry, when the composite geotextile with a closed bottom and an open top is subjected to high-pressure grouting, the composite geotextile can be swelled, the expanded composite geotextile stops expanding in volume when contacting the side wall of a drilled hole, and the expanded composite geotextile is attached to the side wall to form a cylinder; when a connectivity channel or a karst cave is formed on the side wall, the high-pressure concrete grout pushes the part of geotextile to protrude towards the channel, and a pile is formed after the high-pressure concrete grout is condensed and hardened, so that compared with the conventional cast-in-situ bored pile used in a karst area, the problems of grout loss, grout leakage, necking and the like in the conventional cast-in-situ bored pile construction in the karst area are effectively solved, the pile forming quality is greatly improved, the integrity of the cast-in-situ bored pile and rocks in the karst area with the connectivity channel can be greatly improved, the bearing capacity of the pile is greatly improved, and the safety of a pile foundation in the karst area is ensured;
2. the cladding part is made of composite geotextile with good physical and mechanical performance indexes such as tensile strength, tear resistance, puncture resistance and the like, higher strength and better extensibility, the composite geotextile made of the material can well play a role in flexibility, and has larger deformation modulus, when a connectivity channel or a karst cave exists at the side wall, the combination of a reinforced concrete pile and a karst area foundation rock foundation with a connectivity channel is enhanced by a dendritic body structure formed by the concrete slurry bulges, the contact area between the pile and the foundation is increased, the two pile bodies can achieve the purpose of jointly bearing, the pile side frictional resistance of the pile foundation is obviously improved, and the integral bearing capacity of the foundation is improved; meanwhile, the coating has the characteristics of good acid and alkali resistance, corrosion resistance, aging resistance, good permeability and the like;
3. the cast-in-situ bored pile can also be suitable for karst areas with a connectivity channel, which are difficult to completely find out the geological conditions of the engineering, and can also fully improve the integrity of the pile and the rock, thereby ensuring the bearing capacity requirement of basic engineering;
4. the cast-in-situ bored pile has the advantages of simple construction method and fewer construction steps, can enable workers to construct easily, ensures the requirements of construction quality and bearing capacity, can save construction time and engineering cost, and improves construction efficiency.
Drawings
FIG. 1 is a geological profile adapted for use in a karst area having connected passageways according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of pile boring suitable for a karst area with connectivity channels according to an embodiment of the invention;
fig. 3 is a schematic diagram of a reinforcement cage before pile forming of the pile body suitable for a karst area with a connectivity channel according to an embodiment of the invention;
FIG. 4 is a schematic diagram of a bored pile suitable for use in a karst area having connectivity channels according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a pile end assembly additionally arranged at the bottom of a reinforcement cage when a bored pile suitable for a karst area with a connectivity channel meets a communication channel or a karst cave before a pore channel according to an embodiment of the invention;
in fig. 4, 1-bedrock, 2-connectivity channel, 3-karst cave, 4-pile, 5-composite geotextile, 6-concrete, 7-reinforcement cage, 8-pile end component, 9-PPR pipe, 10-ring iron wire, 11-grouting pipe orifice, 12-hanger interface, 13-dendritic structure.
Detailed Description
The following detailed description of the present invention is provided in conjunction with the accompanying drawings, but it should be understood that the scope of the present invention is not limited to the specific embodiments. Throughout the specification and claims, unless explicitly stated otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or component but not the exclusion of any other element or component.
As shown in fig. 1 to 5, a bored pile suitable for a karst region having a connectivity channel according to an embodiment of the present invention is suitable for a karst region having a connectivity channel, and a bedrock 1 of the karst region having a connectivity channel includes a connectivity channel 2 and a cavern 3.
The bored pile includes: the pile body 4 is a reinforced concrete pile, and comprises concrete (before and after setting and hardening) 6, a reinforcement cage 7 and a pile end assembly 8 which can be arranged, if a communication channel 2 or a karst cave 3 exists in front of a pore channel, the pile end assembly 8 is additionally arranged at the bottom of the reinforcement cage 7, as shown in figure 5, and is arranged in a communication karst area; the covering piece is a composite geotextile 5 with a closed bottom and an open top, the composite geotextile 5 covers the outside of the reinforcement cage 7 before the pile body is formed, the composite geotextile 5 is slightly encircled on the reinforcement cage 7 by an annular iron wire 10, the diameter of the composite geotextile 5 is larger than the diameter of the reinforcement cage 7 before the pile body is formed, and the length of the composite geotextile 5 is larger than the height of the reinforcement cage 7 before the pile body is formed. The diameter of the composite geotextile 5 is more than 0.2m larger than the diameter of the reinforcement cage 7 before the pile body is formed, and the length of the composite geotextile 5 is more than 2m larger than the length of the reinforcement cage 7 before the pile body is formed.
In a use state, the lifting appliance is connected with a lifting appliance interface 12 arranged on the reinforcement cage 7, the lifting appliance fills and blocks the reinforcement cage 7 and the composite geotextile 5 into the connectivity channel 2 in the connectivity karst area under the action of high-pressure concrete slurry, and the composite geotextile 5 extending to the connectivity channel is filled with concrete 6 to form a dendritic body structure 13.
According to the cast-in-situ bored pile, the flexibility of the composite geotextile is utilized, when the composite geotextile 5 with the closed bottom and the open top is subjected to high-pressure grouting, the grouting is performed into the PPR pipe 9 through the grouting pipe opening 11, and the PPR pipe is left in the pile body 4 after the pile body is formed and serves as a longitudinal steel bar to increase the strength of the reinforcement cage. And during grouting, the part of the composite geotextile 5, which meets the connectivity channel, of the side wall of the pore channel is pushed by high-pressure slurry to fill and block the connectivity channel 2 in the karst to form a dendritic body structure 13, so that the reinforced concrete can be better combined with the whole rock in the connectivity karst area, the pile side frictional resistance of the pile foundation is obviously improved, and the whole bearing capacity of the foundation is improved. Compared with the existing cast-in-situ bored pile used in the karst area, the cast-in-situ bored pile effectively prevents the diseases such as slurry leakage and necking, and greatly improves the pile forming quality.
As shown in fig. 4-5, the method for forming the bored pile suitable for the karst region with the connected channels of the invention comprises the following steps:
(1) firstly, the cladding member is sleeved outside the reinforcement cage 7, and the cladding member is lightly buckled outside the reinforcement cage 7 by the annular iron wire in a certain furling degree, wherein the tightness degree of the annular iron wire can ensure that the cladding member does not fall off in the process of putting the reinforcement cage 7 downwards and can also ensure that the annular iron wire is broken off by the pressure of slurry in the process of high-pressure grouting (the cladding member is fixed on the reinforcement cage 7 and can be easily broken off under the action of the pressure of grouting); the manufacturing method of the annular iron wire comprises the steps that an iron wire with the diameter of about 4mm is wound around the outer part of the cladding piece in a circle and is slightly folded, and the cladding piece is folded outside the reinforcement cage 7 through the annular iron wire, so that the cladding piece is prevented from touching the hole wall and being damaged in the subsequent lowering process;
(2) hoisting a reinforcement cage 7 lightly buckled with a cladding member into a preset position (a position for pre-positioning a pile) of a pile hole by using a hoisting tool, wherein the hoisting tool does not move after the reinforcement cage 7 reaches a specified position, so that the position of the reinforcement cage 7 is ensured to be fixed;
(3) pumping concrete with certain solidification time into the reinforcement cage directly or through a PPR pipe positioned in the middle of the reinforcement cage, adding an early-setting agent into the concrete according to specific construction requirements, then injecting high-pressure concrete grout, and filling and plugging the cladding member into a passage in a karst area with connectivity under the action of grouting pressure;
(4) the pressure intensity of the coating piece is increased by injecting high-pressure concrete grout, the coating piece expands and breaks loose annular iron wires, the expanded coating piece stops volume expansion when contacting with the side wall of a drill hole, the coating piece is attached to the side wall to form a cylinder, when the side wall is drilled in a karst region with a communication channel or a karst cave, the high-pressure concrete grout pushes the part of the coating piece to bulge towards the channel to form a branch-shaped dendritic body structure 13, the dendritic body structure 13 is restrained by the pressure of the concrete grout and the coating piece at the same time, the pressure borne by the dendritic body structure 13 is equal to the restraining force provided by the coating piece when the part bulges to a certain degree, at the moment, the dendritic body structure 13 stops expansion, and a pile is formed after the high-pressure concrete grout is solidified and hardened.
When a communication channel 2 or a karst cave 3 exists at the bottom of a pile hole, a pile end assembly 8 is additionally arranged at the bottom of the reinforcement cage 7, and the structure of the pile end assembly 8 is shown in figure 5.
The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.

Claims (6)

1. The cast-in-situ bored pile suitable for the karst area with the connectivity channel is characterized by comprising a pile body and a cladding part, wherein the pile body is a reinforced concrete pile and at least comprises a concrete pile body and a reinforcement cage, the reinforcement cage is an elongated cage which is enclosed by longitudinal reinforcements and stirrups, and the reinforcement cage is used as a reinforcement cage prefabricated before the pile body is formed into the pile; the coating piece is a composite geotextile with a closed bottom and an open top, the coating piece is coated outside a reinforcement cage before the pile body is formed, the coating piece is arranged in a surrounding manner and is lightly buckled on the reinforcement cage through an annular iron wire, concrete grout is injected into the reinforcement cage at high pressure, the high-pressure concrete grout pushes part of the coating piece to bulge towards the position of the connectivity channel to form a branch-shaped structure in the form of branch bifurcation, and the pile is formed after the high-pressure concrete grout is condensed and hardened; the diameter of the cladding is greater than the diameter of the reinforcement cage and the length of the cladding is greater than the length of the reinforcement cage.
2. The bored pile suitable for karst areas with connectivity channels according to claim 1, wherein when there is connectivity channel or karst cave in the bottom of the pile hole, the bottom of the cladding is added with a pile tip assembly for preventing the bottom of the cladding from being pulled down to crack due to excessive vertical pressure; the pile end assembly is composed of two circular steel plates, one circular steel plate is welded to the bottom of the steel reinforcement cage, the other circular steel plate is arranged outside the cladding piece, four round holes for the threaded steel pipe to pass through are formed in the cladding piece and the circular steel plate at equal intervals, and the two ends of the threaded steel pipe are tightened to clamp the cladding piece through nuts.
3. The bored pile suitable for use in karst areas having a communication channel according to claim 1, wherein the diameter of the cladding is greater than the diameter of the reinforcement cage before the pile body is formed into a pile by more than 0.2 m.
4. The bored pile suitable for use in karst areas with a connective pathway of claim 1, wherein the length of the cladding is more than 2m greater than the length of the reinforcement cage before the pile body is formed.
5. A pile-forming method for bored pile suitable for karst area with connectivity channel according to claims 1-4, characterized by comprising the following steps:
(1) firstly, sheathing the cladding member outside the reinforcement cage, and lightly buckling the cladding member outside the reinforcement cage by using an annular iron wire with a certain furling degree, wherein the furling degree of the annular iron wire is not only capable of ensuring that the cladding member does not fall off in the process of placing the reinforcement cage, but also capable of ensuring that the annular iron wire is broken off by the pressure of slurry in the process of high-pressure grouting;
(2) hoisting a reinforcement cage lightly buckled with a cladding member into a preset position of the pile hole by using a hoisting tool, wherein the hoisting tool does not move any more after the reinforcement cage reaches a specified position, so that the position of the reinforcement cage is ensured to be fixed;
(3) pumping concrete with certain solidification time into the reinforcement cage directly or through a PPR pipe positioned in the middle of the reinforcement cage, adding an early-setting agent into the concrete according to specific construction requirements, then injecting concrete grout under high pressure, and filling and plugging the cladding member into a passage in a karst area with connectivity under the action of grouting pressure;
(4) the injection of the high-pressure concrete grout increases the pressure of the cladding part, the cladding part expands and breaks loose the annular iron wire, the expanded cladding part stops volume expansion when contacting the side wall of the drilled hole, the cladding part is attached to the side wall to form a cylinder, when the side wall is drilled in a karst region with a communication channel or a karst cave, the high-pressure concrete grout pushes the part of the cladding part to bulge towards the channel to form a dendritic body structure in a branch shape, the dendritic body structure is restrained by the pressure of the concrete grout and the cladding part at the same time, the pressure borne by the dendritic body structure is equal to the restraining force provided by the cladding part when the part bulges to a certain degree, at the moment, the dendritic body structure stops expansion, and the pile is formed after the high-pressure concrete grout is solidified and hardened.
6. The pile forming method for the bored pile suitable for the karst region with the communication channel as claimed in claim 5, wherein in the step (1), the annular iron wire is manufactured by surrounding an iron wire of about 4mm around the exterior of the covering member and slightly gathering the iron wire, and the covering member is gathered outside the reinforcement cage through the annular iron wire, so as to prevent the covering member from touching the hole wall and being damaged in the subsequent lowering process.
CN201911052550.7A 2019-10-31 2019-10-31 Cast-in-situ bored pile suitable for karst area with connectivity channel and pile forming method Pending CN110820732A (en)

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王新泉: "《工程地质学》", 31 July 2016 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112855029A (en) * 2021-04-26 2021-05-28 中铁九局集团第七工程有限公司 Goaf drilling external pipe expansion construction method

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