CN112323773A - Rigid-flexible composite uplift pile and installation method thereof - Google Patents

Rigid-flexible composite uplift pile and installation method thereof Download PDF

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Publication number
CN112323773A
CN112323773A CN202011345515.7A CN202011345515A CN112323773A CN 112323773 A CN112323773 A CN 112323773A CN 202011345515 A CN202011345515 A CN 202011345515A CN 112323773 A CN112323773 A CN 112323773A
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China
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pile
rigid
uplift
flexible
uplift pile
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Inventor
孙爱斌
王亚坤
张雪磊
孙兆刚
张国祥
辛建忠
张伟康
李婧
于进庆
卢业旭
李超
吴海刚
赵津茂
管朝鹏
王欣
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China Railway Design Corp
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China Railway Design Corp
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    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
    • E02D5/22—Piles
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D27/00—Foundations as substructures
    • E02D27/10—Deep foundations
    • E02D27/12—Pile foundations
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
    • E02D5/22—Piles
    • E02D5/34—Concrete or concrete-like piles cast in position ; Apparatus for making same
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
    • E02D5/22—Piles
    • E02D5/34—Concrete or concrete-like piles cast in position ; Apparatus for making same
    • E02D5/46—Concrete or concrete-like piles cast in position ; Apparatus for making same making in situ by forcing bonding agents into gravel fillings or the soil

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  • Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Mining & Mineral Resources (AREA)
  • Paleontology (AREA)
  • Civil Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Piles And Underground Anchors (AREA)

Abstract

The invention provides a rigid-flexible composite uplift pile, which comprises a plurality of uplift pile units, wherein each uplift pile unit comprises a rigid uplift pile and a flexible pile, the number of the rigid uplift piles is 1, and the rigid uplift piles are positioned in the center; the number of the flexible piles is multiple, and the flexible piles are arranged around the rigid uplift pile; the rigid uplift pile and the flexible pile are mutually meshed, and the size of meshing is 0.15-0.2 m; adjacent flexible piles are mutually meshed, the size of meshing is not less than 0.25m, and at least two rows of flexible piles are arranged; the uplift pile units are arranged in a ring or grid mode, and the distance between the rigid uplift piles of two adjacent uplift pile units is not less than six times of the diameter of the rigid uplift pile. The invention not only reduces the disturbance to the soil mass or soft soil mass easy to liquefy when the rigid pile is constructed, but also greatly increases the side frictional resistance of the rigid pile compared with the condition that the rigid pile is directly contacted with the soil mass or soft soil mass easy to liquefy, and simultaneously increases the side frictional resistance of the flexible pile.

Description

Rigid-flexible composite uplift pile and installation method thereof
Technical Field
The invention relates to the technical field of municipal engineering, in particular to a rigid-flexible composite uplift pile and an installation method thereof.
Background
In recent years, with the rapid development of urban construction, development and utilization of road traffic and underground spaces have become an inevitable trend of development. A large number of traffic structures penetrating through railways or highways downwards, such as U-shaped grooves or subway shield intervals, underground pipe galleries, underground garages and the like, are built, so that the anti-floating problem of the underground structure becomes very important. And the uplift pile is widely applied to the anti-floating design of the projects.
The main action mechanism of the uplift pile is to resist buoyancy by means of the friction force between the pile body and the surrounding soil layer and the self weight of the pile body. The standard value calculation formula of the uplift limit bearing capacity of the single pile is as follows: t isuk＝∑λi qsikuiliWherein λ isiIs the coefficient of resistance to plucking, qsikIs the standard value of the compression limit side resistance of the i-th layer soil on the surface of the pile side, uiThe circumference of the pile body is shown. In a soft soil area or an earthquake liquefaction area, when the reinforced concrete uplift pile is used alone for construction, the disturbance to the surrounding soil body is large, the standard value of the pile body side resistance is reduced more, the anti-floating effect of the uplift pile is weakened, and certain economic loss is caused.
Meanwhile, when the reinforced concrete uplift pile is used independently in an earthquake liquefied stratum and a soft soil stratum, because the underground water level is high, dewatering is needed firstly to carry out uplift pile drilling construction, but when a plurality of underground structures are close to high-speed rails or other important buildings at present, dewatering measures cannot be adopted, and then the uplift pile is difficult to form holes, and the holes are easily liquefied and collapsed or contracted in the construction process, even quicksand and local collapse are caused, and the pile forming quality of the uplift pile is influenced. Especially, the pile is formed by drilling in silt and fine sand layers below the underground water level, and the pore water pressure in the soil layer can be increased rapidly, so that a large soil squeezing effect is caused, the foundation of the adjacent building around the construction site is raised greatly, and the normal use of the adjacent building is influenced.
The application of the rigid uplift pile in the stratum is limited in economic efficiency and safety because the pile body is difficult to form a hole, the uplift force is reduced too much, the influence on the surrounding environment is large and the like when the rigid uplift pile is used alone for the easily liquefied earthquake and the soft soil stratum, particularly the soft soil with higher sensitivity.
Therefore, a technical scheme which solves the problems of soil extrusion effect, difficult hole forming, too much reduction of the pulling resistance and the like existing in the singly adopted rigid uplift pile and enables the anti-floating design to be more economical and reasonable is urgently needed in the prior art.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a rigid-flexible composite uplift pile and an installation method thereof.
In order to achieve the purpose, the invention is realized by the following technical scheme:
a rigid-flexible composite uplift pile comprises a plurality of uplift pile units, wherein each uplift pile unit comprises a rigid uplift pile and a flexible pile, the number of the rigid uplift piles is 1, and the rigid uplift piles are located in the center; the number of the flexible piles is multiple, and the flexible piles are arranged around the rigid uplift pile; the rigid uplift pile and the flexible pile are mutually meshed, and the size of meshing is 0.15-0.2 m; adjacent flexible piles are mutually meshed, the size of meshing is not less than 0.25m, and at least two rows of flexible piles are arranged; the uplift pile units are arranged in a ring or grid mode, and the distance between the rigid uplift piles of two adjacent uplift pile units is not less than six times of the diameter of the rigid uplift pile.
The section of the rigid uplift pile is circular or square.
The rigid uplift pile is a reinforced concrete drilled pile.
The diameter of the flexible pile is 0.5-0.6 m.
The spacing of the flexible piles is 0.2-0.4 m.
The flexible pile is one of a cement mixing pile, a high-pressure jet grouting pile or a CFG pile.
The invention also provides the following technical scheme.
A method for installing a rigid-flexible composite uplift pile comprises the following steps:
a. arranging a flexible pile;
b. grouting and reinforcing soil around the flexible pile;
c. testing the compressive strength of the flexible pile, and if the compressive strength of the flexible pile reaches the standard, arranging a rigid uplift pile in the center of the flexible pile;
d. grouting and reinforcing the part below 0.6m of the base of the rigid uplift pile;
e. and testing the compressive strength of the rigid uplift pile, if the compressive strength of the rigid uplift pile reaches the standard, removing floating slurry of a part of the rigid uplift pile, which does not meet the compressive strength, and the pile head, and then arranging the structural bottom plate at the top of the rigid uplift pile.
The thickness of the pile head of the rigid uplift pile embedded into the structural bottom plate is not less than 70nm, and in the embodiment, is 100 nm.
And the steel bars of the pile head of the rigid uplift pile are inserted into the structural bottom plate or the upper-layer main steel bars of the building foundation bottom plate.
Compared with the prior art, the invention has the beneficial effects that: on the basis of a traditional rigid uplift pile, the rigid pile is constructed in the range of the reinforced soil body after the reinforced soil body reaches a certain strength by constructing the flexible pile, and the rigid pile is connected with the flexible pile in an occluded manner, so that the rigid-flexible composite uplift pile with a larger outer pile diameter is formed, the contact soil body area of the uplift pile is further increased, the pile side frictional resistance of the rigid-flexible composite uplift pile is larger than that of a single rigid uplift pile with the same diameter, the disturbance to the easily liquefied soil body or soft soil is reduced during the construction of the rigid pile, the side frictional resistance of the rigid pile is greatly increased compared with the condition that the rigid pile is directly contacted with the easily liquefied soil body or soft soil, and the side frictional resistance of the flexible pile is also increased; the pile body self weight of the rigid-flexible composite uplift pile is also improved, and the uplift resistance is further increased; in the construction process, no precipitation measure is needed, so that the adverse effects of construction pumping precipitation on the settlement of the surrounding environment and the like are greatly reduced; in the process of drilling and pile forming, a rigid protective cylinder is not needed, so that the engineering cost is reduced, the foundation is reinforced, and the bearing capacity of the foundation is improved.
Drawings
Fig. 1 is a sectional view of a rigid-flexible composite uplift pile.
Fig. 2 is a vertical sectional view of the rigid-flexible composite uplift pile.
Fig. 3 is a plan view of the rigid-flexible composite uplift pile.
Detailed Description
The invention is further illustrated by the following specific embodiments.
The rigid-flexible composite uplift pile shown in fig. 1-3 comprises a plurality of uplift pile units, wherein each uplift pile unit comprises a rigid uplift pile 1 and a flexible pile 2, the number of the rigid uplift piles 1 is 1, and the rigid uplift piles 1 are located in the center; the number of the flexible piles 2 is multiple, and the flexible piles 2 are arranged around the rigid uplift pile 1; the rigid uplift pile 1 and the flexible pile 2 are mutually occluded, and the size of occlusion is 0.15-0.2 m; adjacent flexible piles 2 are mutually meshed, the size of meshing is not less than 0.25m, and at least two rows of flexible piles 2 are shown in figure 1, and the number of the flexible piles is two in the embodiment; the uplift pile units are arranged in a ring shape. In other embodiments of the present invention, as shown in fig. 3, the uplift pile units are arranged in a grid form, with a longitudinal spacing of L1 and a transverse spacing of L2. The distance between the rigid uplift piles 1 of the two adjacent uplift pile units is not less than six times of the diameter of the rigid uplift pile 1. The diameter of the flexible pile 2 is 0.5-0.6m, in this embodiment 0.5 m. The flexible piles 2 are spaced at a distance of 0.2-0.4m, in this example 0.3 m. The flexible pile 2 is one of a cement mixing pile, a high-pressure jet grouting pile or a CFG pile, and in the embodiment, is a cement mixing pile. The cross section of the rigid uplift pile 1 is circular or square, in this embodiment, the cross section is circular, the diameter of the rigid uplift pile 1 is 1m, and the length of the rigid uplift pile 1 is not less than 20 m. The rigid uplift pile 1 is a reinforced concrete drilled pile.
When the uplift pile is used, a calculation model is established according to project geological conditions, stratum mechanical parameters and the like, the structure meets the uplift force requirement by adjusting parameters such as the diameter of the rigid uplift pile, the pile plane arrangement form, the pile distance, the pile length and the like, and soil around the uplift pile is reinforced by selecting a flexible pile according to the plane arrangement form and the stratum condition of the uplift pile in design, wherein the installation method of the rigid-flexible composite uplift pile comprises the following steps:
a. arranging the flexible pile 2;
b. grouting and reinforcing the soil around the flexible pile 2; according to the diameter, the pile length and the stratum condition of the rigid uplift pile 1, for example, when the pile length is longer, the pile diameter is larger and the stratum at the pile side is worse, the row number and the diameter of the flexible pile 2 can be increased;
c. testing the compressive strength of the flexible pile 2, and if the compressive strength of the flexible pile 2 reaches the standard, arranging a rigid uplift pile 1 in the center of the flexible pile 2;
d. grouting and reinforcing the part below 0.6m of the base of the rigid uplift pile 1;
e. testing the compressive strength of the rigid uplift pile 1, if the compressive strength of the rigid uplift pile 1 reaches the standard, removing floating slurry of a part of the pile head and the part which do not meet the compressive strength on the rigid uplift pile 1, and then arranging the structural bottom plate at the top of the rigid uplift pile 1, wherein the thickness of the pile head of the rigid uplift pile 1 embedded into the structural bottom plate is not less than 70nm, 100nm in the embodiment, and the reinforcing steel bar of the pile head of the rigid uplift pile 1 is inserted into the structural bottom plate. In other embodiments of the invention, the steel bars of the pile head of the rigid uplift pile 1 are inserted into the position of the upper main bars of the foundation slab of the building.
When measuring the compressive strength of the flexible pile 2 and the rigid uplift pile 1, a core sample method is adopted to extract a concrete core sample test piece for detection, and the compressive strength calculation mode of the concrete core sample test piece is as follows:
Figure BDA0002799699920000041
fcoris the compressive strength (MPa) of a concrete core sample specimen,
p is the breaking load (N) measured by the compression test of the core sample specimen,
d is the average diameter (mm) of the core specimen.
And when the compressive strength of the concrete core sample test piece reaches the standard value, the compressive strength reaches the standard.
The above is only a preferred embodiment of the present invention, but the present invention is not limited to the above-mentioned specific embodiments, and those skilled in the art can make several variations and modifications without departing from the inventive concept of the present invention, which fall into the protection scope of the present invention.

Claims (8)

1. A rigid-flexible composite uplift pile comprises a plurality of uplift pile units and is characterized in that the uplift pile units comprise rigid uplift piles and flexible piles, the number of the rigid uplift piles is 1, and the rigid uplift piles are located in the center; the number of the flexible piles is multiple, and the flexible piles are arranged around the rigid uplift pile; the rigid uplift pile and the flexible pile are mutually meshed, and the size of meshing is 0.15-0.2 m; adjacent flexible piles are mutually meshed, the size of meshing is not less than 0.25m, and at least two rows of flexible piles are arranged; the uplift pile units are arranged in a ring or grid mode, and the distance between the rigid uplift piles of two adjacent uplift pile units is not less than six times of the diameter of the rigid uplift pile.
2. The rigid-flexible composite uplift pile according to claim 1, wherein the cross section of the rigid uplift pile is circular or square.
3. The rigid-flexible composite uplift pile according to claim 1, wherein the rigid uplift pile is a reinforced concrete bored pile.
4. The rigid-flexible composite uplift pile according to claim 1, wherein the diameter of the flexible pile is 0.5-0.6 m.
5. The rigid-flexible composite uplift pile according to claim 1, wherein the flexible piles have a pitch of 0.2-0.4 m.
6. The rigid-flexible composite uplift pile according to claim 1, wherein the flexible pile is one of a cement mixing pile, a high-pressure jet grouting pile or a CFG pile.
7. A method for installing a rigid-flexible composite uplift pile is characterized by comprising the following steps:
a. arranging a flexible pile;
b. grouting and reinforcing soil around the flexible pile;
c. testing the compressive strength of the flexible pile, and if the compressive strength of the flexible pile reaches the standard, arranging a rigid uplift pile in the center of the flexible pile;
d. grouting and reinforcing the part below 0.6m of the base of the rigid uplift pile;
e. and testing the compressive strength of the rigid uplift pile, if the compressive strength of the rigid uplift pile reaches the standard, removing floating slurry of a part of the rigid uplift pile, which does not meet the compressive strength, and the pile head, and then arranging the structural bottom plate at the top of the rigid uplift pile.
8. The method of installing a rigid-flexible composite uplift pile according to claim 7, wherein the thickness of the pile head of the rigid uplift pile embedded in the structural bottom plate is not less than 70 nm.
CN202011345515.7A 2020-11-26 2020-11-26 Rigid-flexible composite uplift pile and installation method thereof Pending CN112323773A (en)

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Application Number Priority Date Filing Date Title
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CN112323773A true CN112323773A (en) 2021-02-05

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