CN109403392B - System and method for measuring and calculating horizontal counter force coefficient of soil body - Google Patents

System and method for measuring and calculating horizontal counter force coefficient of soil body Download PDF

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CN109403392B
CN109403392B CN201811004296.9A CN201811004296A CN109403392B CN 109403392 B CN109403392 B CN 109403392B CN 201811004296 A CN201811004296 A CN 201811004296A CN 109403392 B CN109403392 B CN 109403392B
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soil body
depth
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CN109403392A (en
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魏立峰
周健
潘炳成
叶居东
谢荣晖
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Ningbo Water Conservancy And Hydropower Planning And Design Institute Co ltd
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    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D33/00—Testing foundations or foundation structures
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D1/00—Investigation of foundation soil in situ
    • E02D1/08—Investigation of foundation soil in situ after finishing the foundation structure
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
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Abstract

The invention discloses a system and a method for measuring and calculating a horizontal counter force coefficient of a soil body, wherein the system for measuring and calculating the horizontal counter force coefficient of the soil body comprises the following steps: the device comprises at least one test pile, pile pressing equipment, horizontal load applying equipment and a data processor, wherein strain gauges and displacement sensors are arranged at different heights inside the test pile and used for measuring axial strain values and displacement values at different strain heights inside the test pile, the data processor is in communication connection with the displacement sensors and the strain gauges respectively, and the data processor is suitable for acquiring data measured by the displacement sensors and the strain gauges and calculating the relation between horizontal counter force of soil layers with different depths and soil body displacement. The invention has simple structure and lower cost, and realizes accurate measurement and calculation by an economic and effective mode to obtain the horizontal counter force coefficient of the soil body which can be applied to the actual engineering design.

Description

System and method for measuring and calculating horizontal counter force coefficient of soil body
Technical Field
The invention relates to the technical field of geotechnical engineering investigation, in particular to a system and a method for measuring and calculating a horizontal reaction force coefficient of a soil body.
Background
The horizontal counterforce coefficient of the soil body is a design parameter reflecting the relationship between the horizontal action and the deformation of the soil body borne by deep foundation structures such as foundation piles and the like in geotechnical engineering, reflects the relationship between the horizontal counterforce of soil layers with different depths and the displacement of the soil body, is an important parameter in geotechnical investigation design, and is directly related to the design of the foundation structure subjected to the horizontal action.
However, the existing method for measuring and calculating the horizontal reaction force coefficient of the soil body has some defects. In the prior art, the horizontal reaction force coefficient of the soil body is generally valued by two modes of a horizontal load test and a reference area experience. The horizontal load test has longer period and higher cost. Although the lateral pressure test and the flat shovel lateral expansion test in the conventional exploration means can reflect the horizontal stress-strain relationship of the soil body to a certain extent, the test data of the tests are measured under the deformation condition of a shallow foundation and have magnitude difference with the horizontal displacement of a deep foundation, so that the parameters obtained by the tests cannot directly guide the actual engineering design.
On the other hand, in the actual engineering design, for the engineering with a more urgent construction period or the temporary engineering, the value of the horizontal reaction force coefficient of the soil body is generally obtained according to the regional experience within the range of the standard guidance. However, the range of the standard guidance is generally wide, and taking the upper limit value and the lower limit value as guidance to take values of the horizontal reaction force coefficient of the soil body respectively often leads to completely different design calculation structures. Uncertainty in the guidance index usually involves higher risk or excessive cost investment.
Therefore, the soil horizontal reaction force coefficient which can guide the actual engineering design and is accurately measured and obtained has important research significance in geotechnical engineering.
Disclosure of Invention
The invention aims to provide a system and a method for measuring and calculating a horizontal counter force coefficient of a soil body, which have the advantages of simple structure and lower cost, and can accurately measure and calculate the horizontal counter force coefficient of the soil body in an economic and effective mode to be applied to actual engineering design.
According to one aspect of the present invention, there is provided a system for measuring horizontal soil reaction force coefficient, comprising:
the device comprises at least one test pile, strain gauges and displacement sensors are arranged at different heights inside the test pile and used for measuring axial strain values and displacement values at different strain heights inside the test pile;
the pile pressing equipment is used for penetrating the test pile into a specified position and depth in a test soil body;
the horizontal load applying equipment is used for applying a preset load in the horizontal direction to the pile top of the test pile; and
and the data processor is respectively in communication connection with the displacement sensor and the strain gauge and is suitable for acquiring data measured by the displacement sensor and the strain gauge and calculating the relationship between horizontal counter force of soil layers with different depths and soil displacement.
Preferably, the pile pressing equipment is a static pile pressing machine, and the horizontal load applying equipment is a horizontal jack.
Preferably, two strain gauges and one displacement sensor are provided at each preset height inside the test pile.
According to the preferred embodiment of the invention, the pile tops are kept flush after the pile pressing equipment penetrates into the test soil body, and the lengths of different test piles are different.
Preferably, the pile body material of the test pile is one or a combination of ultrahigh-performance reinforced concrete (UHPC), ultrahigh-performance concrete (UHPC) and a steel structure.
Preferably, the test pile adopts a rectangular cross section symmetrical reinforcing bar design to strengthen the overall strength.
Preferably, the pile top part of the test pile is subjected to steel plate head covering treatment so as to protect the pile top position of the test pile from being damaged easily due to penetration force and preset load in the horizontal direction; the tip part of the pile head of the test pile is also treated by a steel plate packet head, so that the test pile can be conveniently penetrated into a test soil body.
According to another aspect of the present invention, the present invention further provides a method for measuring and calculating a horizontal counterforce coefficient of a soil body, which comprises the following steps:
(S1) penetrating the test pile into the test soil at a designated position and depth;
(S2) applying a preset load F in the horizontal direction to the pile top portion of the test pile;
(S3) measuring the horizontal surface of the test pile on the test soil body through a strain gaugeLower depth ziAxial strain value epsilon ofiFor the depth z of the test pile below the horizontal surface of the test soil bodyiThe strain section of the test soil body is established with a bending moment balance equation, and the surface and the depth z of the test soil body are measured and calculated by combining a bending moment calculation formulaiHorizontal counter force p of soil body distributed among placesi(z)，
Wherein the bending moment equilibrium equation is as follows:
Figure BDA0001783664700000031
the bending moment calculation formula is as follows:
Figure BDA0001783664700000032
wherein the depth of the horizontal surface of the test soil body is set to 0, MiIs a depth ziBending moment, p, experienced at the cross-section at strain heighti(z) is the horizontal surface and depth z of the test soil bodyiHorizontal counter-force of soil body distributed between locations, ziFor the depth of the cross section with different strain heights below the horizontal surface of the test soil body, 2h and b are respectively the length and width of the rectangular strain cross section of the test pile, F is the preset load in the horizontal direction, and z is the preset load in the horizontal direction0The length of the test pile is higher than the horizontal surface of the test soil body, z is the depth value under the horizontal surface of the test soil body, E is the elastic modulus of the material of the pile body of the test pile, and h0The length of the strain gauge from the central axis of the test pile is epsiloniDepth z measured for the strain gaugeiThe axial strain value of the point can be obtained by the formulas (1) and (2) to obtain the surface and depth z of the tested soil bodyiHorizontal counter force p of soil body distributed among placesi(z)；
(S4) measuring the depth z by a displacement sensoriThe corresponding displacement value;
(S5) changing the depth ziAnd (5) repeating the steps (S3) to (S4) to obtain the relation between the horizontal reaction force of soil layers with different depths and the soil displacement.
Preferably, in order to improve the estimation accuracy, the method for estimating the horizontal reaction force coefficient of the soil further comprises the following steps:
(S6) changing the size of the preset load F, repeating the steps (S3) to (S5), and measuring multiple groups of experimental data so as to establish the relationship between the horizontal counter forces of multiple groups of soil layers with different depths and the soil displacement.
Preferably, in order to improve the measurement and calculation accuracy, in the step (S1), test piles with different lengths may be driven into the test soil body by the pile pressing device and the pile tops may be kept flush, and a horizontal load applying device is used to apply a preset load in the horizontal direction to a plurality of test piles, so that on one hand, a plurality of sets of measurement and calculation data may be measured and used for mutual verification, and on the other hand, the effect of fixing the horizontal load applying device may also be achieved.
Preferably, in the step (S1), the test pile is static-pressed into the test soil body by a static pile press; in the step (S2), a preset load in the horizontal direction is applied to the pile top portion of the test pile by using a horizontal jack.
According to a preferred embodiment of the invention, two strain gauges and at least one displacement sensor are provided at each preset height inside the test pile for measuring axial strain and displacement values at different strain heights inside the test pile.
The above and other objects, features, and advantages of the present invention will become further apparent from the following detailed description, the accompanying drawings, and the appended claims.
Drawings
FIG. 1 is a schematic configuration of a system for estimating a horizontal soil counterforce coefficient according to a preferred embodiment of the invention;
fig. 2 is a schematic diagram of the displacement of a test pile after being subjected to a preset load in the horizontal direction according to a preferred embodiment of the present invention;
fig. 3 is a schematic view of the force analysis of a test pile after a preset load in the horizontal direction according to a preferred embodiment of the present invention, showing ziStress conditions at depth;
FIG. 4 is a rootZ of test piles according to the preferred embodiment of the present inventioniA schematic of a strain cross section at depth;
FIG. 5 is a schematic flow chart of a method for measuring and calculating a horizontal soil reaction force coefficient according to a preferred embodiment of the invention;
in the figure: a test pile 10; a pile top 11; a pile head 12; a horizontal load applying device 20; a data processor 30; a strain gauge 40; a displacement sensor 50; the test soil horizontal surface 60.
Detailed Description
The invention is further described with reference to the drawings and the detailed description, and it should be noted that any combination of the embodiments or technical features described below can be used to form a new embodiment without conflict.
The following description is presented to disclose the invention so as to enable any person skilled in the art to practice the invention. The preferred embodiments in the following description are given by way of example only, and other obvious variations will occur to those skilled in the art. The basic principles of the invention, as defined in the following description, may be applied to other embodiments, variations, modifications, equivalents, and other technical solutions without departing from the spirit and scope of the invention.
It will be understood by those skilled in the art that in the present disclosure, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in an orientation or positional relationship indicated in the drawings for ease of description and simplicity of description, and do not indicate or imply that the referenced devices or components must be in a particular orientation, constructed and operated in a particular orientation, and thus the above terms are not to be construed as limiting the present invention.
It is understood that the terms "a" and "an" should be interpreted as meaning that a number of one element or element is one in one embodiment, while a number of other elements is one in another embodiment, and the terms "a" and "an" should not be interpreted as limiting the number.
Referring to fig. 1 to 4 of the drawings, a system for measuring and calculating a horizontal counter force coefficient of a soil body according to a preferred embodiment of the present invention will be explained in the following description, which has a simple structure and low cost, and can accurately measure and calculate the horizontal counter force coefficient of the soil body applicable to actual engineering design in an economical and effective manner.
As shown in fig. 1, the system for measuring and calculating the horizontal reaction force coefficient of the soil body comprises at least one test pile 10, a pile pressing device (not shown in the figure), a horizontal load applying device 20 and a data processor 30, wherein strain gauges 40 and displacement sensors 50 are arranged at different heights inside the test pile 10 and used for measuring axial strain values and displacement values at different strain heights inside the test pile 10.
The pile pressing equipment is used for penetrating the test pile 10 to the designated position and depth in the test soil body, and the horizontal load applying equipment 20 is used for applying a preset load in the horizontal direction to the pile top 11 of the test pile 10.
Preferably, in this embodiment, the pile pressing device is a static pile pressing machine, and the horizontal load applying device 20 is a horizontal jack.
The data processor 30 is respectively connected with the displacement sensor 50 and the strain gauge 40 in a communication way, and the data processor 30 is suitable for acquiring data measured by the displacement sensor 50 and the strain gauge 40 at different heights in the test pile 10 and calculating the relationship between horizontal counter force of soil layers with different depths and soil displacement.
Preferably, the test pile 10 is made of an ultrahigh-performance reinforced concrete material, and a rectangular-section symmetrical reinforcement design is adopted to enhance the overall strength and avoid the influence of deformation of the test pile 10 in the stress process on the accuracy of the measurement result. It is easily understood by those skilled in the art that the pile body material of the test pile 10 is not limited in the present embodiment, and in other possible preferred embodiments, the test pile 10 may also be made of, but not limited to, Ultra High Performance Concrete (UHPC), steel structure, etc.
Preferably, the pile top 11 of the test pile 10 is treated by a steel plate toe cap to protect the pile top 11 of the test pile 10 from being damaged by the penetration force and the preset load in the horizontal direction, and the tip 12 of the pile head of the test pile 10 is also treated by the steel plate toe cap to facilitate the penetration of the test pile 10 into the test soil.
In order to improve the accuracy of the measurement, two strain gauges 40 and one displacement sensor 50 are preferably provided at each predetermined height inside the test pile 10.
Specifically, a preset load F in the horizontal direction is applied to the pile top 11 portion of the test pile 10 by the horizontal load applying apparatus 20. As shown in fig. 2 to 4, the test pile 10 is displaced in the test soil under the load. The depth z of the test pile 10 below the horizontal test soil surface 60 is then measured by the strain gauge 40 disposed inside the test pile 10iAxial strain value epsilon ofiFor said test pile 10, depth z below horizontal surface 60 of test soil bodyiThe strain section of the test soil body is established with a bending moment balance equation, and the surface 60 and the depth z of the test soil body are measured and calculated by combining a bending moment calculation formulaiHorizontal counter force p of soil body distributed among placesi(z)。
Wherein the bending moment equilibrium equation is as follows:
Figure BDA0001783664700000071
the bending moment calculation formula is as follows:
Figure BDA0001783664700000072
wherein the depth at the horizontal surface 60 of the test soil mass is set to 0, MiIs a depth ziBending moment, p, experienced at the cross-section at strain heighti(z) is the horizontal surface 60 and depth z of the test soiliHorizontal counter-force of soil body distributed between locations, ziTest soil body water for different strain height cross sectionsDepth below the flat surface 60, 2h and b being the length and width, respectively, of the rectangular strain section of the test pile, F being the predetermined load in the horizontal direction, z0The length of the test pile 10 is higher than the horizontal surface 60 of the test soil body, z is the depth value under the horizontal surface 60 of the test soil body, E is the elastic modulus of the pile body material of the test pile 10, and h0The length of the strain gauge 40 from the central axis of the test pile 10, epsiloniFor the axial strain values measured by the strain gauge 40 at different strain heights, the test soil surface 60 and the depth z can be obtained from the equations (1) and (2)iHorizontal counter force p of soil body distributed among placesi(z)；
Then, the depth z is measured by the displacement sensor 50 provided inside the test pile 10iAt a corresponding displacement value and, finally, the depth z is changediThe above operations are repeated to obtain the relationship between the horizontal counter force of the soil layers with different depths and the displacement of the soil body.
In the preferred embodiment, the test pile 10 is a square pile with a rectangular cross-section, so 2h and b are the length and width, respectively, of the rectangular cross-section of the test pile 10. However, it is easily understood by those skilled in the art that the cross-sectional shape of the test pile 10 is not limited in the present invention, and in other possible preferred embodiments, the cross-sectional shape of the test pile 10 may be, but is not limited to, circular, triangular, oval, etc., and other cross-sectional shapes are also applicable to the method for calculating the horizontal reaction force coefficient of the soil body disclosed in the present invention.
In order to improve the measurement precision by acquiring different measurement data, a plurality of groups of experimental data can be measured by changing the preset load F in the horizontal direction, so that the relationship between the horizontal counter force of a plurality of groups of soil layers with different depths and the soil displacement is established.
In addition, the test piles 10 with different lengths can be penetrated into the test soil body through the pile pressing equipment and the pile tops are kept flush, and meanwhile, one horizontal load applying equipment 20 is shared to apply preset loads in the horizontal direction to a plurality of test piles, so that on one hand, a plurality of groups of measurement and calculation data can be measured and used for mutual checking, and on the other hand, the effect of fixing the horizontal load applying equipment can also be achieved.
As shown in fig. 5, the present invention further provides a method for measuring and calculating a horizontal counterforce coefficient of a soil body, which comprises the following steps:
(S1) penetrating the test pile into the test soil at a designated position and depth;
(S2) applying a preset load F in the horizontal direction to the pile top portion of the test pile;
(S3) measuring the depth z of the test pile below the horizontal surface of the test soil body through a strain gaugeiAxial strain value epsilon ofiFor the depth z of the test pile below the horizontal surface of the test soil bodyiThe strain section of the test soil body is established with a bending moment balance equation, and the surface and the depth z of the test soil body are measured and calculated by combining a bending moment calculation formulaiHorizontal counter force p of soil body distributed among placesi(z)，
Wherein the bending moment equilibrium equation is as follows:
Figure BDA0001783664700000091
the bending moment calculation formula is as follows:
Figure BDA0001783664700000092
wherein the depth of the horizontal surface of the test soil body is set to 0, MiIs a depth ziBending moment, p, experienced at the cross-section at strain heighti(z) is the horizontal surface and depth z of the test soil bodyiHorizontal counter-force of soil body distributed between locations, ziFor the depth of the cross section with different strain heights below the horizontal surface of the test soil body, 2h and b are respectively the length and width of the rectangular strain cross section of the test pile, F is the preset load in the horizontal direction, and z is the preset load in the horizontal direction0The length of the test pile is higher than the horizontal surface of the test soil body, z is the depth value under the horizontal surface of the test soil body, E is the elastic modulus of the material of the pile body of the test pile, and h0The length of the strain gauge from the central axis of the test pile is epsiloniDepth z measured for the strain gaugeiAxial direction ofThe strain value can be obtained by the formulas (1) and (2) to obtain the surface and depth z of the tested soil bodyiHorizontal counter force p of soil body distributed among placesi(z)；
(S4) measuring the depth z by a displacement sensoriThe corresponding displacement value;
(S5) changing the depth ziAnd (5) repeating the steps (S3) to (S4) to obtain the relation between the horizontal reaction force of soil layers with different depths and the soil displacement.
Preferably, in order to improve the estimation accuracy, the method for estimating the horizontal reaction force coefficient of the soil further comprises the following steps:
(S6) changing the size of the preset load F, repeating the steps (S3) to (S5), and measuring multiple groups of experimental data so as to establish the relationship between the horizontal counter forces of multiple groups of soil layers with different depths and the soil displacement.
In the preferred embodiment, the test pile is a square pile with a rectangular cross section, so 2h and b are the length and width of the rectangular cross section of the test pile, respectively. However, it is easily understood by those skilled in the art that the cross-sectional shape of the test pile is not limited in the present invention, and in other possible preferred embodiments, the cross-sectional shape of the test pile may be, but is not limited to, circular, triangular, oval, etc., and other cross-sectional shapes are also applicable to the method for measuring and calculating the horizontal reaction force coefficient of the soil body disclosed in the present invention.
Preferably, in order to improve the measurement and calculation accuracy, in the step (S1), test piles with different lengths may be driven into the test soil body by the pile pressing device and the pile tops may be kept flush, and a horizontal load applying device is used to apply a preset load in the horizontal direction to a plurality of test piles, so that on one hand, a plurality of sets of measurement and calculation data may be measured and used for mutual verification, and on the other hand, the effect of fixing the horizontal load applying device may also be achieved.
Preferably, in the step (S1), the test pile is static-pressed into the test soil body by a static pile press; in the step (S2), a preset load in the horizontal direction is applied to the pile top portion of the test pile by using a horizontal jack.
Preferably, two strain gauges and at least one displacement sensor are arranged at each preset height inside the test pile and used for measuring and obtaining axial strain values and displacement values at different strain heights inside the test pile.
It will be appreciated by persons skilled in the art that the embodiments of the invention described above and shown in the drawings are given by way of example only and are not limiting of the invention. The objects of the invention have been fully and effectively accomplished. The functional and structural principles of the present invention have been shown and described in the examples, and any variations or modifications of the embodiments of the present invention may be made without departing from the principles.

Claims (8)

1. A system for estimating horizontal soil reaction force coefficients, comprising:
the device comprises at least one test pile, strain gauges and displacement sensors are arranged at different heights inside the test pile and used for measuring axial strain values and displacement values at different strain heights inside the test pile;
the pile pressing equipment is used for penetrating the test pile into a specified position and depth in a test soil body;
the horizontal load applying equipment is used for applying a preset load in the horizontal direction to the pile top of the test pile; and
the data processor is respectively in communication connection with the displacement sensor and the strain gauge and is suitable for acquiring data measured by the displacement sensor and the strain gauge and calculating the relationship between horizontal counter force of soil layers with different depths and soil displacement; the data processor measures the depth z of the test pile below the horizontal surface of the test soil body by acquiring the strain gaugeiAxial strain value epsilon ofiFor the depth z of the test pile below the horizontal surface of the test soil bodyiThe strain section of the test soil body is established with a bending moment balance equation, and the surface and the depth z of the test soil body are measured and calculated by combining a bending moment calculation formulaiHorizontal counter force p of soil body distributed among placesi(z)，
Wherein the bending moment equilibrium equation is as follows:
Figure FDA0002900792870000011
the bending moment calculation formula is as follows:
Figure FDA0002900792870000012
wherein the depth of the horizontal surface of the test soil body is set to 0, MiIs a depth ziBending moment, p, experienced at the cross-section at strain heighti(z) is the horizontal surface and depth z of the test soil bodyiHorizontal counter-force of soil body distributed between locations, ziFor the depth of the cross section with different strain heights below the horizontal surface of the test soil body, 2h and b are respectively the length and width of the rectangular strain cross section of the test pile, F is the preset load in the horizontal direction, and z is the preset load in the horizontal direction0The length of the test pile is higher than the horizontal surface of the test soil body, z is the depth value under the horizontal surface of the test soil body, E is the elastic modulus of the material of the pile body of the test pile, and h0The length of the strain gauge from the central axis of the test pile is epsiloniDepth z measured for the strain gaugeiThe axial strain value of the point can be obtained by the formulas (1) and (2) to obtain the surface and depth z of the tested soil bodyiHorizontal counter force p of soil body distributed among placesi(z); and measuring the depth z by means of a displacement sensoriThe corresponding displacement value; the data processor for changing the depth ziThe relationship between the horizontal counter force of soil layers with different depths and the displacement of the soil body is obtained according to the size of the soil body.
2. The system for estimating horizontal soil reaction force coefficients of claim 1 wherein said pile pressing apparatus is a static pile press and said horizontal load applying apparatus is a horizontal jack.
3. The system for measuring and calculating the horizontal soil reaction force coefficient of claim 1 wherein two strain gauges and one displacement sensor are provided at each predetermined height inside the test pile.
4. The system for measuring and calculating the horizontal reaction force coefficient of a soil body according to claim 1, wherein the pile body material of the test pile is one or a combination of ultra-high performance reinforced concrete (UHPC), ultra-high performance concrete (UHPC) and a steel structure, a rectangular section symmetrical reinforcement design is adopted, and the pile top part and the pile head tip part are treated by a steel plate toe cap.
5. A method for measuring and calculating a horizontal counter force coefficient of a soil body is characterized by comprising the following steps:
(S1) penetrating the test pile into the test soil at a designated position and depth;
(S2) applying a preset load F in the horizontal direction to the pile top portion of the test pile;
(S3) measuring the depth z of the test pile below the horizontal surface of the test soil body through a strain gaugeiAxial strain value epsilon ofiFor the depth z of the test pile below the horizontal surface of the test soil bodyiThe strain section of the test soil body is established with a bending moment balance equation, and the surface and the depth z of the test soil body are measured and calculated by combining a bending moment calculation formulaiHorizontal counter force p of soil body distributed among placesi(z)，
Wherein the bending moment equilibrium equation is as follows:
Figure FDA0002900792870000021
the bending moment calculation formula is as follows:
Figure FDA0002900792870000031
wherein the depth of the horizontal surface of the test soil body is set to 0, MiIs a depth ziBending moment, p, experienced at the cross-section at strain heighti(z) is the horizontal surface and depth z of the test soil bodyiHorizontal counter-force of soil body distributed between locations, ziFor the depth of the cross section with different strain heights below the horizontal surface of the test soil body, 2h and b are respectively the length and width of the rectangular strain cross section of the test pile, F is the preset load in the horizontal direction, and z is the preset load in the horizontal direction0The length of the test pile is higher than the horizontal surface of the test soil body, z is the depth value under the horizontal surface of the test soil body, E is the elastic modulus of the material of the pile body of the test pile, and h0The length of the strain gauge from the central axis of the test pile is epsiloniDepth z measured for the strain gaugeiThe axial strain value of the point can be obtained by the formulas (1) and (2) to obtain the surface and depth z of the tested soil bodyiHorizontal counter force p of soil body distributed among placesi(z)；
(S4) measuring the depth z by a displacement sensoriThe corresponding displacement value;
(S5) changing the depth ziAnd (5) repeating the steps (S3) to (S4) to obtain the relation between the horizontal reaction force of soil layers with different depths and the soil displacement.
6. The method for estimating a soil horizontal counterforce coefficient of claim 5, further comprising the steps of:
(S6) changing the size of the preset load F, repeating the steps (S3) to (S5) and establishing the relationship between the horizontal counter forces of a plurality of groups of soil layers with different depths and the soil displacement.
7. The method for estimating a horizontal soil reaction force coefficient according to claim 5 wherein in said step (S1), said test pile is hydrostatic-inserted into the test soil by means of a hydrostatic pile press; in the step (S2), a preset load in the horizontal direction is applied to the pile top portion of the test pile by using a horizontal jack.
8. The method for measuring and calculating the horizontal soil reaction force coefficient according to claim 5, wherein two strain gauges and at least one displacement sensor are arranged at each preset height inside the test pile for measuring the axial strain value and the displacement value at different strain heights inside the test pile.
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