CN112362008B - Method for measuring pile foundation displacement and axial force under condition of humidifying expansive soil foundation - Google Patents

Method for measuring pile foundation displacement and axial force under condition of humidifying expansive soil foundation Download PDF

Info

Publication number
CN112362008B
CN112362008B CN202011160979.0A CN202011160979A CN112362008B CN 112362008 B CN112362008 B CN 112362008B CN 202011160979 A CN202011160979 A CN 202011160979A CN 112362008 B CN112362008 B CN 112362008B
Authority
CN
China
Prior art keywords
pile
soil
displacement
axial force
section
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
CN202011160979.0A
Other languages
Chinese (zh)
Other versions
CN112362008A (en
Inventor
刘云龙
李明宇
王增辉
雷雪
胡少磊
张帅兵
杨舒
于小淞
刘椿杨
刘乃铭
刘愈宽
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Zhengzhou University
Original Assignee
Zhengzhou University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Zhengzhou University filed Critical Zhengzhou University
Priority to CN202011160979.0A priority Critical patent/CN112362008B/en
Publication of CN112362008A publication Critical patent/CN112362008A/en
Application granted granted Critical
Publication of CN112362008B publication Critical patent/CN112362008B/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B21/00—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant
    • G01B21/02—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D33/00—Testing foundations or foundation structures
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/10—Geometric CAD
    • G06F30/13—Architectural design, e.g. computer-aided architectural design [CAAD] related to design of buildings, bridges, landscapes, production plants or roads
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Geometry (AREA)
  • Structural Engineering (AREA)
  • Theoretical Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Civil Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Architecture (AREA)
  • Paleontology (AREA)
  • Mining & Mineral Resources (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Computational Mathematics (AREA)
  • Mathematical Analysis (AREA)
  • Mathematical Optimization (AREA)
  • Pure & Applied Mathematics (AREA)
  • Evolutionary Computation (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Force Measurement Appropriate To Specific Purposes (AREA)
  • Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)

Abstract

本发明提供一种膨胀土地基增湿条件下桩基位移和轴力的测量方法，包括步骤1，将膨胀土体中不同土层的垂直位移采用线性函数拟合；步骤2，确定不同土层中桩侧传力弹簧刚度；步骤3，测定膨胀土体在增湿条件下的材料参数，计算桩土界面剪切强度；步骤4，根据桩体截面处轴力和桩侧摩阻力相等关系以及该截面处的位移与轴力的关系，得到桩基的微分控制方程；步骤5，将膨胀土体中不同土层的垂直位移与得出的桩位移方程相结合，得出桩体相邻段之间的位移和轴力关系，步骤6，得出桩体的位移和轴力方程；步骤7，得出桩端处的轴力根据桩体底部第n段的轴力和位移，进而累计各段的轴力和位移情况，得出增湿条件下土体膨胀引起桩基轴力和位移的分布情况。

Figure 202011160979

The invention provides a method for measuring pile foundation displacement and axial force under the condition of humidification of expansive soil foundation, comprising step 1, fitting the vertical displacements of different soil layers in the expansive soil body with a linear function; step 2, determining different soil layers Step 3: Determine the material parameters of the expansive soil under humidified conditions, and calculate the shear strength of the pile-soil interface; Step 4, according to the equal relationship between the axial force at the pile section and the pile side friction resistance and The relationship between the displacement at the section and the axial force, the differential control equation of the pile foundation is obtained; step 5, the vertical displacement of the different soil layers in the expansive soil is combined with the obtained pile displacement equation, and the adjacent section of the pile body is obtained. The relationship between the displacement and the axial force, step 6, obtain the displacement and axial force equation of the pile; step 7, obtain the axial force at the pile end according to the axial force and displacement of the nth section at the bottom of the pile, and then accumulate each The axial force and displacement of the section are obtained, and the distribution of the axial force and displacement of the pile foundation caused by soil expansion under humidification conditions is obtained.

Figure 202011160979

Description

Method for measuring pile foundation displacement and axial force under condition of humidifying expansive soil foundation
Technical Field
The invention relates to the field of pile foundation design in expansive soil, in particular to a method for measuring pile foundation displacement and axial force under the condition of humidifying an expansive soil foundation.
Background
With the acceleration of the large-scale engineering construction process in China, especially, most of the projects in China are in the expansive soil area, the soil body in the expansive soil area is deformed under the humidification effect under the humidification condition that natural precipitation events or other artificial activities (such as pipeline leakage in the expansive soil) humidify the soil body, and the safety and the stability of the projects can be directly influenced; therefore, geotechnical infrastructure engineering designed or built in expansive soil areas presents a major challenge, and the costs incurred in repairing, redesigning and rebuilding foundation engineering under such geological conditions are as high as billions of dollars each year. Particularly, under the condition of rainfall infiltration, when the pile foundation is in an expansive land area, the soil expansion effect can seriously affect the pile foundation, so that the foundation is unevenly deformed, and the upper structure is damaged. Therefore, the safety evaluation of the pile foundation in the expansive soil under the humidification effect has important significance for the construction of infrastructure.
In the past, a large number of researchers have carried out theoretical analysis work on the calculation of the internal force and the displacement of the pile foundation, but the existing load transmission mechanism analysis method of the pile foundation is based on the principle of saturated soil mechanics, the displacement and the internal force distribution condition of the pile foundation caused by the expansion of the expansive soil foundation are obtained through calculation, the influence of the change of the substrate suction force on the load transmission of the pile foundation under the humidification condition of the soil body and the softening phenomenon of the soil body caused by the increase of the water content of the soil body on the interface of the pile body and the soil are not considered, and therefore the pile body displacement relation and the axial force distribution condition of the pile foundation in the soil body are inaccurate. In the actual engineering, the soil bodies at different depths are deformed differently under the humidification condition of the expanded soil body, and the calculation result obtained by the analytic formula proposed by the past scholars is often in a larger difference with the actual engineering.
Therefore, there is a need to develop a method for measuring pile foundation displacement and axial force under the condition of humidifying the expansive soil foundation, so as to solve the above problems in the prior art.
Disclosure of Invention
The invention aims to provide a method for measuring pile foundation displacement and axial force under the condition of expansive soil foundation humidification, which can accurately and rapidly determine the pile foundation displacement and internal force distribution under the condition of expansive soil humidification.
The invention relates to a method for measuring pile foundation displacement and axial force under the condition of humidifying an expansive soil foundation, which comprises the following steps:
step 1, measuring the sizes and material parameters of the pile foundation and the expanded soil body before humidification, wherein the parameters comprise: rigidity E of pile bodypApThe thickness S of the expansion soil body where the length L of pile body section diameter d, pile body and pile body place divides the expansion soil body into n layers with the pile body, and according to the deformation condition of different soil layers, the vertical displacement of different soil layers in the expansion soil body adopts linear function fitting: Δ hn＝Hnzn+anWherein, Δ hnIs the vertical displacement of the n-th layer of soil, HnIs the expansion deformation coefficient of the n-th soil body, znThe distance between the nth layer of soil and the ground, anThe constant term of the expansion deformation of the nth layer of soil body is used;
step 2, measuring material parameters of pile side soil before humidification, determining the rigidity of a pile side force transfer spring in different soil layers, wherein the rigidity of the pile side force transfer spring is defined as pile side frictional resistance generated when a pile body with unit length and a soil body around the pile body generate unit relative displacement, and a calculation formula of the rigidity of the n-th layer of pile side force transfer spring is as follows:
Figure GDA0003375042580000021
wherein r is0The radius of the pile body is the radius of the pile body,
Figure GDA0003375042580000022
is the maximum value of the shear strength of the pile-soil interface, wcrThe relative displacement of the corresponding pile soil when the shear strength of the pile soil interface is maximum;
step 3, measuring material parameters of the expanded soil body under the humidifying condition, and calculating the shear strength of the pile-soil interface, namely the pile side friction resistance value tau under the maximum displacement of the pile body and the soil body around the pile bodysu，τsuThe calculation formula is as follows:
Figure GDA0003375042580000023
wherein c'aFor effective cohesion, δ' is the effective internal friction angle, upsilon is the Poisson ratio, u is the effective internal friction angleaIs pore pressure, uwIs the pore water pressure, (u)a-uw)rIs the suction of the matrix, theta is the water content of the current soil body, thetarIs the residual water content, θsTo saturated water content, σsIs under normal stress, PsFor soil expansion pressure, EaThe compression modulus of the soil body;
step 4, analyzing the stress condition of the pile body in the pile foundation, dividing the pile body and the expansive soil body into n sections, and according to the equal relation between the axial force at the section of the pile body and the side frictional resistance of the pile:
Figure GDA0003375042580000024
and the relationship of displacement at this section to axial force:
Figure GDA0003375042580000025
obtaining a differential control equation of the pile foundation:
Figure GDA0003375042580000026
wherein P isznIs the axial force of a certain section of the pile body, ApIs the cross-sectional area of the pile body, EpThe modulus of elasticity of the pile body is,
Figure GDA0003375042580000027
for a displacement of a section of the pile body, τsnRepresenting the pile side friction resistance value corresponding to the nth layer of soil; solving a differential control equation of the pile foundation to obtain a pile displacement equation:
Figure GDA0003375042580000028
wherein
Figure GDA0003375042580000029
A. B is undetermined coefficient;
and 5, combining the vertical displacement of different soil layers in the expanded soil body with the obtained pile displacement equation to obtain the displacement equation of the nth section of pile body:
Figure GDA0003375042580000031
axial force equation:
Figure GDA0003375042580000032
conversion to matrix form:
Figure GDA0003375042580000033
wherein
Figure GDA0003375042580000034
According to the characteristic that the displacement and the axial force of the contact surface between two adjacent sections of the pile body are equal, namely the stress conditions of the top of the nth section of the pile body and the bottom of the (n-1) th section of the pile body are the same, the undetermined constants at the contact surface are the same,
Figure GDA0003375042580000035
obtaining the relation between the displacement and the axial force between adjacent sections of the pile body,
Figure GDA0003375042580000036
step 6, because the water content of the expanded soil body is increased under the humidification condition, the pile-soil interface strength can generate a softening phenomenon, and according to the relation between the relative displacement and the shearing strength of the pile-soil interface measured in the step 2, the shearing strength of the pile-soil interface after the interface is softened is reduced to tauspAnd finally obtaining the displacement and axial force equation of the pile body:
Figure GDA0003375042580000037
wherein tau issp(n)Humidifying soft for pile soil interfaceThe shear strength of the pile-soil interface after chemical modification, wherein L is the length of a pile body, and d is the diameter of the section of the pile body;
and 7, measuring material parameters of a soil body at the pile end, wherein for a pile foundation, the end part of the pile body generally acts in a stable underlying layer area, and the axial force P at the pile endzbBy settling displacement w of pile foundationbTo obtain:
Figure GDA0003375042580000038
wherein G issbIs the shear modulus of the lower horizontal layer soil body of the pile foundation, upsilonbThe Poisson ratio of the soil body of the lower lying layer of the pile foundation is shown; and accumulating and solving the axial force and displacement conditions of the nth section, the nth-1 section, the nth-2 section … … the 2 nd section and the 1 st section according to the axial force and displacement of the nth section at the bottom of the pile body to obtain the distribution condition of the axial force and displacement of the pile foundation caused by soil body expansion under the condition of humidifying the expansive soil foundation.
The invention has the beneficial effects that:
(1) the method considers the change of the expansive deformation of the expansive soil along the depth under the humidification effect, the expansive soil is a soil body which can be expanded and deformed when encountering water, and the deformation condition has a great relationship with the infiltration condition of the soil body. According to the method, the soil layer is divided into different sections, and the deformation conditions of the soil body of the different sections are considered. Effectively avoids the rough judgment of the expansion deformation of the soil body in the prior method and fully considers the deformation of the soil body under the humidification condition of the actual engineering.
(2) The method considers the change of the shear strength of the pile soil interface of the expansive soil under the humidification action. When the soil body is changed from an unsaturated state to a saturated state, the suction force of the matrix in the soil body is changed, so that the pile-soil interface strength is softened. The method analyzes the strength change after the pile-soil interface generates the softening phenomenon, and considers the interaction relation of the pile and the soil, so that the method is more consistent with the actual engineering.
(3) The method divides the pile body into n sections for calculation, and the solving method is a semi-analytical method. Compared with the traditional method, the method has small calculated amount, and the obtained result can clearly show the displacement and internal force distribution conditions of different positions of the pile body and know the load transfer rule in the pile foundation.
Drawings
FIG. 1 is a schematic flow chart of a measurement method of the present invention;
FIG. 2 is a diagram showing the numerical calculation results in the experimental example of the present invention.
Detailed Description
The present invention is further illustrated by the following specific examples, which are intended to be illustrative, not limiting and are not intended to limit the scope of the invention.
An embodiment of a method for measuring pile foundation displacement and axial force under the condition of humidifying an expansive soil foundation is shown in figures 1 and 2, and the method comprises the following steps:
step 1, measuring the sizes and material parameters of the pile foundation and the expanded soil body before humidification, wherein the parameters comprise: rigidity E of pile bodypApThe thickness S of the expansion soil body where the length L of pile body section diameter d, pile body and pile body place divides the expansion soil body into n layers with the pile body, and according to the deformation condition of different soil layers, the vertical displacement of different soil layers in the expansion soil body adopts linear function fitting: Δ hn＝Hnzn+anWherein, Δ hnIs the vertical displacement of the n-th layer of soil, HnIs the expansion deformation coefficient of the n-th soil body, znThe distance between the nth layer of soil and the ground, anThe constant term of the expansion deformation of the nth layer of soil body is used;
step 2, measuring material parameters of pile side soil before humidification, determining the rigidity of a pile side force transfer spring in different soil layers, wherein the rigidity of the pile side force transfer spring is defined as pile side frictional resistance generated when a pile body with unit length and a soil body around the pile body generate unit relative displacement, and a calculation formula of the rigidity of the n-th layer of pile side force transfer spring is as follows:
Figure GDA0003375042580000041
wherein r is0The radius of the pile body is the radius of the pile body,
Figure GDA0003375042580000042
is the maximum value of the shear strength of the pile-soil interface, wcrThe relative displacement of the corresponding pile soil when the shear strength of the pile soil interface is maximum;
step 3, measuring material parameters of the expanded soil body under the humidifying condition, and calculating the shear strength of the pile-soil interface, namely the pile side friction resistance value tau under the maximum displacement of the pile body and the soil body around the pile bodysu，τsuThe calculation formula is as follows:
Figure GDA0003375042580000051
wherein c'aFor effective cohesion, δ' is the effective internal friction angle, upsilon is the Poisson ratio, u is the effective internal friction angleaIs pore pressure, uwIs the pore water pressure, (u)a-uw)rIs the suction of the matrix, theta is the water content of the current soil body, thetarIs the residual water content, θsTo saturated water content, σsIs under normal stress, PsFor soil expansion pressure, EaThe compression modulus of the soil body;
step 4, analyzing the stress condition of the pile body in the pile foundation, dividing the pile body and the expansive soil body into n sections, and according to the equal relation between the axial force at the section of the pile body and the side frictional resistance of the pile:
Figure GDA0003375042580000052
and the relationship of displacement at this section to axial force:
Figure GDA0003375042580000053
obtaining a differential control equation of the pile foundation:
Figure GDA0003375042580000054
wherein P isznIs the axial force of a certain section of the pile body, ApIs the cross-sectional area of the pile body, EpThe modulus of elasticity of the pile body is,
Figure GDA0003375042580000055
for a displacement of a section of the pile body, τsnRepresenting the pile side friction resistance value corresponding to the nth layer of soil; solving a differential control equation of the pile foundation to obtain a pile displacement equation:
Figure GDA0003375042580000056
wherein
Figure GDA0003375042580000057
A. B is undetermined coefficient;
and 5, combining the vertical displacement of different soil layers in the expanded soil body with the obtained pile displacement equation to obtain the displacement equation of the nth section of pile body:
Figure GDA0003375042580000058
axial force equation:
Figure GDA0003375042580000059
conversion to matrix form:
Figure GDA00033750425800000510
wherein
Figure GDA00033750425800000511
According to the characteristic that the displacement and the axial force of the contact surface between two adjacent sections of the pile body are equal, namely the stress conditions of the top of the nth section of the pile body and the bottom of the (n-1) th section of the pile body are the same, the undetermined constants at the contact surface are the same,
Figure GDA00033750425800000512
obtaining the relation between the displacement and the axial force between adjacent sections of the pile body,
Figure GDA00033750425800000513
step 6, because the water content of the expanded soil body is increased under the humidification condition, the pile-soil interface strength can generate a softening phenomenon, and according to the relation between the relative displacement and the shearing strength of the pile-soil interface measured in the step 2, the shearing strength of the pile-soil interface after the interface is softened is reduced to tauspAnd finally obtaining the displacement and axial force equation of the pile body:
Figure GDA0003375042580000061
wherein tau issp(n)The shear strength of the pile-soil interface after the pile-soil interface is humidified and softened is shown, wherein L is the length of a pile body, and d is the diameter of the section of the pile body;
and 7, measuring material parameters of a soil body at the pile end, wherein for a pile foundation, the end part of the pile body generally acts in a stable underlying layer area, and the axial force P at the pile endzbBy settling displacement w of pile foundationbTo obtain:
Figure GDA0003375042580000062
wherein G issbIs the shear modulus of the lower horizontal layer soil body of the pile foundation, upsilonbThe Poisson ratio of the soil body of the lower lying layer of the pile foundation is shown; and accumulating and solving the axial force and displacement conditions of the nth section, the nth-1 section, the nth-2 section … … the 2 nd section and the 1 st section according to the axial force and displacement of the nth section at the bottom of the pile body to obtain the distribution condition of the axial force and displacement of the pile foundation caused by soil body expansion under the condition of humidifying the expansive soil foundation.
Test example:
model experiments were performed using Guangxi Nanning soil. The test was carried out in a cylindrical tub of diameter 50cm and height 87cm, the bottom of which was filled with 10cm of gravel, 16cm of medium sand and 58cm of swelling soil. The model pile adopts a PVC pipe with the diameter of 5cm, the PVC pipe is filled with a fly ash mixture, the pile length is 64cm, the pile is buried in a soil body for 58cm, stress sheets are attached to the periphery of the pile body, a soil pressure box is placed at the pile end, and soil for a model test is artificially irrigated from the ground surface for 230 hours to enable the soil body to reach a saturated state.
Model Material parameters are shown in Table 1
TABLE 1 model test Material parameters
Figure GDA0003375042580000063
The test result shows that the top surface of the expansive soil is raised by 4.12cm, and the upward displacement of the pile body is 0.359 cm. The vertical expansion pressure was 400 kPa. Meanwhile, numerical simulation calculation is adopted, and the depth of the soil body uplift from the ground surface to 30cm is in a linear relation.
The method is adopted to calculate and divide the pile body into 8 sections, and the pile-soil relative displacement corresponding to the shear strength of the peak pile-soil interface is 0.01 m. FIG. 2 is a diagram showing the result of numerical calculation, where depth is depth, Pile axial stress is Pile axial force, Experiment is Experiment, Simulation is Simulation, and deployed method is the method of the present embodiment. As can be seen from fig. 2, the method of the present scheme is better in agreement with the test data, and meanwhile, it can be seen that the maximum axial force position of the pile body obtained by the method is close to the test result, which indicates that the method can better estimate the pile side friction force and the bearing capacity of the underlying layer. The method can better estimate the position of the maximum axial force of the pile body.
It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.

Claims (1)

1. A method for measuring pile foundation displacement and axial force under the condition of humidifying an expansive soil foundation is characterized by comprising the following steps:
step 1, measuring the sizes and material parameters of the pile foundation and the expanded soil body before humidification, wherein the parameters comprise: rigidity E of pile bodypApThe thickness S of the expansion soil body where the length L of pile body section diameter d, pile body and pile body place divides the expansion soil body into n layers with the pile body, and according to the deformation condition of different soil layers, the vertical displacement of different soil layers in the expansion soil body adopts linear function fitting: Δ hn＝Hnzn+anWherein, Δ hnIs the vertical displacement of the n-th layer of soil, HnIs the expansion deformation coefficient of the n-th soil body, znThe distance between the nth layer of soil and the ground, anThe constant term of the expansion deformation of the nth layer of soil body is used;
step 2, measuring material parameters of pile side soil before humidification, determining the rigidity of a pile side force transfer spring in different soil layers, wherein the rigidity of the pile side force transfer spring is defined as pile side frictional resistance generated when a pile body with unit length and a soil body around the pile body generate unit relative displacement, and a calculation formula of the rigidity of the n-th layer of pile side force transfer spring is as follows:
Figure FDA0003375042570000011
wherein r is0The radius of the pile body is the radius of the pile body,
Figure FDA0003375042570000012
is the maximum value of the shear strength of the pile-soil interface, wcrThe relative displacement of the corresponding pile soil when the shear strength of the pile soil interface is maximum;
step 3, measuring material parameters of the expanded soil body under the humidifying condition, and calculating the shear strength of the pile-soil interface, namely the pile side friction resistance value tau under the maximum displacement of the pile body and the soil body around the pile bodysu，τsuThe calculation formula is as follows:
Figure FDA0003375042570000013
wherein c'aFor effective cohesion, δ' is the effective internal friction angle, upsilon is the Poisson ratio, u is the effective internal friction angleaIs pore pressure, uwIs the pore water pressure, (u)a-uw)rIs the suction of the matrix, theta is the water content of the current soil body, thetarIs the residual water content, θsTo saturated water content, σsIs under normal stress, PsFor soil expansion pressure, EaThe compression modulus of the soil body;
step 4, analyzing the stress condition of the pile body in the pile foundation, dividing the pile body and the expansive soil body into n sections, and according to the equal relation between the axial force at the section of the pile body and the side frictional resistance of the pile:
Figure FDA0003375042570000014
and the relationship of displacement at this section to axial force:
Figure FDA0003375042570000015
obtaining a differential control equation of the pile foundation:
Figure FDA0003375042570000016
wherein P isznIs the axial force of a certain section of the pile body, ApIs the cross-sectional area of the pile body, EpThe modulus of elasticity of the pile body is,
Figure FDA0003375042570000021
for a certain section of pile bodyDisplacement, τsnRepresenting the pile side friction resistance value corresponding to the nth layer of soil; solving a differential control equation of the pile foundation to obtain a pile displacement equation:
Figure FDA0003375042570000022
wherein
Figure FDA0003375042570000023
A. B is undetermined coefficient;
and 5, combining the vertical displacement of different soil layers in the expanded soil body with the obtained pile displacement equation to obtain the displacement equation of the nth section of pile body:
Figure FDA0003375042570000024
axial force equation:
Figure FDA0003375042570000025
conversion to matrix form:
Figure FDA0003375042570000026
wherein
Figure FDA0003375042570000027
According to the characteristic that the displacement and the axial force of the contact surface between two adjacent sections of the pile body are equal, namely the stress conditions of the top of the nth section of the pile body and the bottom of the (n-1) th section of the pile body are the same, the undetermined constants at the contact surface are the same,
Figure FDA0003375042570000028
obtaining the relation between the displacement and the axial force between adjacent sections of the pile body,
Figure FDA0003375042570000029
step 6, because the water content of the expanded soil body is increased under the humidifying condition, the pile-soil interface strength can generate the softening phenomenon, and the pile-soil interface relative displacement and the shear measured in the step 2 are used for measuring the pile-soil interface relative displacement and the shearShear strength relationship, the shear strength of the pile-soil interface after the interface is softened is reduced to tauspAnd finally obtaining the displacement and axial force equation of the pile body:
Figure FDA00033750425700000210
wherein tau issp(n)The shear strength of the pile-soil interface after the pile-soil interface is humidified and softened is shown, wherein L is the length of a pile body, and d is the diameter of the section of the pile body;
and 7, measuring material parameters of a soil body at the pile end, wherein for a pile foundation, the end part of the pile body generally acts in a stable underlying layer area, and the axial force P at the pile endzbBy settling displacement w of pile foundationbTo obtain:
Figure FDA00033750425700000211
wherein G issbIs the shear modulus of the lower horizontal layer soil body of the pile foundation, upsilonbThe Poisson ratio of the soil body of the lower lying layer of the pile foundation is shown; and accumulating and solving the axial force and displacement conditions of the nth section, the nth-1 section, the nth-2 section … … the 2 nd section and the 1 st section according to the axial force and displacement of the nth section at the bottom of the pile body to obtain the distribution condition of the axial force and displacement of the pile foundation caused by soil body expansion under the condition of humidifying the expansive soil foundation.
CN202011160979.0A 2020-10-27 2020-10-27 Method for measuring pile foundation displacement and axial force under condition of humidifying expansive soil foundation Expired - Fee Related CN112362008B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202011160979.0A CN112362008B (en) 2020-10-27 2020-10-27 Method for measuring pile foundation displacement and axial force under condition of humidifying expansive soil foundation

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202011160979.0A CN112362008B (en) 2020-10-27 2020-10-27 Method for measuring pile foundation displacement and axial force under condition of humidifying expansive soil foundation

Publications (2)

Publication Number Publication Date
CN112362008A CN112362008A (en) 2021-02-12
CN112362008B true CN112362008B (en) 2022-01-18

Family

ID=74510541

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202011160979.0A Expired - Fee Related CN112362008B (en) 2020-10-27 2020-10-27 Method for measuring pile foundation displacement and axial force under condition of humidifying expansive soil foundation

Country Status (1)

Country Link
CN (1) CN112362008B (en)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113191013B (en) * 2021-05-19 2022-04-19 中国海洋大学 Monitoring method suitable for foundation scouring depth of tension leg type marine fan
CN114154320A (en) * 2021-11-24 2022-03-08 广东省高速公路有限公司 Method and equipment for measuring deformation characteristic parameters of saturated soil foundation
CN114491740B (en) * 2021-12-31 2022-09-02 清华大学 Physical and multi-modal data driven building structure generation method and equipment
CN115081089B (en) * 2022-07-27 2023-01-31 中国长江三峡集团有限公司 Method for determining axial force distribution model of reinforced material of reinforced retaining wall and distribution calculation method
CN117973165B (en) * 2024-04-02 2024-06-28 湖南大学 Method for calculating pile internal force and displacement of horizontal loaded pile in deep soft soil area

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0849405A1 (en) * 1988-12-29 1998-06-24 Takechi Engineering Co., Ltd. Methods of determining capability and quality of foundation piles and of designing foundation piles, apparatus for measuring ground characteristics, method of making hole for foundation pile such as cast-in-situ pile and apparatus therefor
CN106202980A (en) * 2016-08-24 2016-12-07 山西省交通科学研究院 A kind of swelled ground is humidified under Condition of Rainfall Infiltration and expands method for numerical simulation
CN109736157A (en) * 2019-02-25 2019-05-10 长沙理工大学 Deformation prediction method of highway expansive soil subgrade based on moisture balance

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0849405A1 (en) * 1988-12-29 1998-06-24 Takechi Engineering Co., Ltd. Methods of determining capability and quality of foundation piles and of designing foundation piles, apparatus for measuring ground characteristics, method of making hole for foundation pile such as cast-in-situ pile and apparatus therefor
CN106202980A (en) * 2016-08-24 2016-12-07 山西省交通科学研究院 A kind of swelled ground is humidified under Condition of Rainfall Infiltration and expands method for numerical simulation
CN109736157A (en) * 2019-02-25 2019-05-10 长沙理工大学 Deformation prediction method of highway expansive soil subgrade based on moisture balance

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
The Mechanical Damage of Pavement Structure in the Humidification Deformation of Expansive Soil Roadbed;Jianguo, Wei;《International Conference on Intelligent System Design and Engineering Application (ISDEA 2010)》;20101231;全文 *
渗水作用下膨胀土中单桩承载变形特性研究;刘建新等;《铁道建筑技术》;20200420(第04期);全文 *

Also Published As

Publication number Publication date
CN112362008A (en) 2021-02-12

Similar Documents

Publication Publication Date Title
CN112362008B (en) Method for measuring pile foundation displacement and axial force under condition of humidifying expansive soil foundation
Indraratna et al. Soft ground improvement via vertical drains and vacuum assisted preloading
CN105735373B (en) Method for measuring ultimate bearing capacity of single precast pile
CN101220600B (en) Tangent modulus correcting method for non-linear sedimentation computation of foundation
CN106485012A (en) A kind of computational methods of soft soil foundation pit safety factor of stability
CN108374403A (en) The ultra high energy level that is humidified handles 25m or more collapsible loess foundation construction methods
Liu et al. Study on the lateral soil resistance acting on the buried pipeline
CN108169456A (en) A kind of collapsible loess estimates big pressure evaluation method
CN101845815A (en) Method for calculating and processing uprush plastic failures of confined water foundation pits of soft soil strata
Chou et al. Seasonal freezing-thawing process and hydrothermal characteristics of soil on the Loess Plateau, China
CN112597673B (en) Method for determining effect of servo support system on foundation pit deformation control under rainfall condition
CN110377935B (en) Method for predicting change of excess pore water pressure along depth of soil body around pile in pile sinking process
CN108121831A (en) The Computing Method for Vertical Bearing Capacity of the wide shallow formula bucket foundation cover bearing mode of major diameter
Gupta et al. Bearing capacity and settlement of footing resting on confined loose silty sands
CN109033622B (en) Method for determining uplift amount of bottom pile foundation of salinized soil road cutting bed after reinforcement
CN106570323A (en) Calculation method for vertical bearing capacity of major-diameter combined type bucket foundation
Wang et al. Experimental Analysis of Vertical Deformation and Bearing Characteristics of Bridge Piles in High and Steep Slopes
Yu et al. A groundwater flow model for excavation of coastal earthen sites: Case study Jintoushan site, China
Murison et al. Comparison of swell behaviour of highly expansive clay through field monitoring and centrifuge modelling
CN1587523A (en) Dynamic simulation design method for highway soft foundation treatment construction
CN110263366A (en) A kind of method that determining suspension type water-stop curtain is inserted into depth in precipitation water-bearing layer
Szymański et al. The factors determining the deformations of organic subsoil under embankment
Tommy et al. Py Curve for Estimation Lateral Bearing Capacity of Single Bored Pile in Overconsolidated Soils Using The Three-Dimensional Finite Element Method.
CN117312796A (en) Integral equation general solution method for vertical bearing characteristics of non-equilong pile composite foundation
Andhiska et al. THE EFFECT OF PILE CROSS-SECTION AREA AND STRAIGHTNESS ON FRICTION CAPACITY IN SOFT CLAY SOIL BASED ON LABORATORY MODEL SCALE

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant
CF01 Termination of patent right due to non-payment of annual fee

Granted publication date: 20220118

CF01 Termination of patent right due to non-payment of annual fee