CN114526860B - Calibration method of simply supported beam type soil pressure sensor - Google Patents
Calibration method of simply supported beam type soil pressure sensor Download PDFInfo
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- CN114526860B CN114526860B CN202210169809.1A CN202210169809A CN114526860B CN 114526860 B CN114526860 B CN 114526860B CN 202210169809 A CN202210169809 A CN 202210169809A CN 114526860 B CN114526860 B CN 114526860B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L25/00—Testing or calibrating of apparatus for measuring force, torque, work, mechanical power, or mechanical efficiency
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- 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
- G01L5/0028—Force sensors associated with force applying means
Abstract
The invention discloses a calibration method of a simply supported beam type soil pressure sensor, which comprises the following steps: s1: measuring the width and the clear span length of a simply supported plate of the simply supported beam type soil pressure sensor; s2: applying concentrated loads to the simply supported beam type soil pressure sensor span step by step to obtain the strain of the middle and lower edges of the simply supported beam type soil pressure sensor span, and obtaining the linear slope of the concentrated loads acting on the simply supported beam type soil pressure sensor span and the strain of the middle and lower edges of the simply supported beam type soil pressure sensor span; s3: acquiring a sandy soil internal friction angle of a simply supported beam type soil pressure sensor embedding position; s4: acquiring a strain response value of a simply supported beam type soil pressure sensor buried in a soil body under the action of soil pressure; s5: and calibrating the soil pressure strength borne by the simply supported beam type soil pressure sensor. The method has high test precision and good reliability, and solves the technical problem of soil pressure test in the prior art that the influence of soil arching effect is not well considered.
Description
Technical Field
The invention belongs to the technical field of soil pressure sensor calibration, and particularly relates to a calibration method of a simply supported beam type soil pressure sensor.
Background
Soil pressure is an important index for representing the mechanical state of soil body, and accurate measurement of soil pressure is a key problem in the technical field of geotechnical engineering. The simple beam type soil pressure sensor is manufactured by pasting a strain gauge in the central area of a simple beam type plate, and is widely applied to scientific and technological research and engineering practice.
In the prior art, a simply supported beam type soil pressure sensor is calibrated under the action of concentrated load, namely: different mid-span concentration force F i Under the action of the micro strain epsilon of the cross-center lower edge of the sensor, the micro strain epsilon of the cross-center lower edge of the sensor is obtained i (ii) a With F i Is the ordinate, ε i Performing linear fitting on the abscissa to obtain a linear slope alpha; assuming that the soil pressure acting on the sensor is approximately uniformly distributed load, and based on the fact that the midspan bending moment generated under the action of uniformly distributed soil pressure p and concentrated force F is the same, the soil pressure strength of the sensor is obtained
Wherein l 0 The length of the simple support plate is clear, and the width of the simple support plate is b. It has the problems that: in the prior art, a simple beam type soil pressure sensor calibration method assumes that a soil pressure distribution mode is a uniform distribution mode. However, a large number of researches show that the actual working environment of the soil pressure sensor is complex, the soil pressure sensor is different from the rigidity of the soil body, the surface of the sensor is easy to generate obvious soil arching effect, the actual soil pressure acts on the sensor in a non-uniform distribution mode, the soil arching effect on the surface of the sensor is ignored in the existing calibration method, the change of the soil arching effect along with the strength of the soil body is not considered, the soil pressure test result is smaller, and the deviation is increased along with the increase of the strength of the soil body.
Disclosure of Invention
The invention provides a calibration method of a simply supported beam type soil pressure sensor in order to solve the problems.
The technical scheme of the invention is as follows: a calibration method of a simply supported beam type soil pressure sensor comprises the following steps:
s1: measuring the width and the clear span length of a simply supported plate of the simply supported beam type soil pressure sensor;
s2: applying concentrated loads to the simply supported beam type soil pressure sensor span step by step to obtain the strain of the middle and lower edges of the simply supported beam type soil pressure sensor span, and obtaining the linear slope of the concentrated loads acting on the simply supported beam type soil pressure sensor span and the strain of the middle and lower edges of the simply supported beam type soil pressure sensor span;
s3: acquiring a sandy soil internal friction angle of a burying position of a simply supported beam type soil pressure sensor;
s4: acquiring a strain response value of a simply supported beam type soil pressure sensor buried in a soil body under the action of soil pressure;
s5: calibrating the soil pressure strength born by the simply supported beam type soil pressure sensor according to the width of the simply supported plate of the simply supported beam type soil pressure sensor, the net span length of the simply supported plate of the simply supported beam type soil pressure sensor, the concentrated load acting in the simply supported beam type soil pressure sensor, the linear slope of the strain of the middle lower edge of the corresponding simply supported beam type soil pressure sensor, the sandy soil internal friction angle of the embedded position of the simply supported beam type soil pressure sensor and the strain response value of the simply supported beam type soil pressure sensor embedded in a soil body under the action of soil pressure.
Further, in step S2, a specific method for acquiring the concentrated load acting in the simply supported beam type earth pressure sensor span and the slope of the strain straight line of the corresponding simply supported beam type earth pressure sensor span center lower edge is as follows: and taking the concentrated load acting in the simply supported beam type soil pressure sensor span as a vertical coordinate, taking the strain of the middle lower edge of the corresponding simply supported beam type soil pressure sensor span as a horizontal coordinate, and performing linear fitting to obtain the linear slope of the concentrated load acting in the simply supported beam type soil pressure sensor span and the strain of the middle lower edge of the corresponding simply supported beam type soil pressure sensor span.
Further, in step S3, a sandy soil internal friction angle of the simply supported beam type soil pressure sensor burying position is obtained through a soil test.
Further, in step S5, the calculation formula of the soil pressure strength p borne by the simply supported beam type soil pressure sensor is:
wherein b represents the width of the simply supported plate of the simply supported beam type soil pressure sensor, and l 0 Representing the net span length of a simple beam earth pressure sensor,
the method comprises the steps of representing a sandy soil internal friction angle of a simply supported beam type soil pressure sensor burying position, representing a strain response value of the simply supported beam type soil pressure sensor buried in a soil body under the action of soil pressure, and representing a linear slope of a concentrated load acting in a simply supported beam type soil pressure sensor span and strain of a corresponding middle lower edge of the simply supported beam type soil pressure sensor span.
Further, the calibration method is suitable for the range of internal friction angle
The sandy soil of (1).
The invention has the beneficial effects that: the method not only considers the non-uniform distribution of the soil pressure caused by the soil arching effect, but also obtains the soil pressure calibration formula of the sensor suitable for different soil body strengths according to the difference of the soil arching effect. The soil pressure tested by the method is verified with a theoretical calculated value, and the relative error is very small, which shows that the method has high test precision and good reliability, solves the technical problem of soil pressure test that the influence of soil arching effect is not well considered in the prior art, can test the soil pressure more accurately, and reduces the deviation caused by the soil arching effect.
Drawings
FIG. 1 is a flow chart of a calibration method of a simply supported beam type soil pressure sensor;
FIG. 2 is a diagram of a symmetrical zigzag-shaped non-uniform distribution pattern of sandy soil in a loose state;
FIG. 3 is a diagram of a symmetrical triangular non-uniform distribution pattern when sandy soil is in a medium density state;
FIG. 4 is a diagram of a symmetrical parabolic non-uniform distribution mode when sandy soil is in a compact state.
Detailed Description
The embodiments of the present invention will be further described with reference to the accompanying drawings.
As shown in FIG. 1, the invention provides a calibration method of a simply supported beam type soil pressure sensor, which comprises the following steps:
s1: measuring the width and the clear span length of a simply supported plate of the simply supported beam type soil pressure sensor;
s2: applying concentrated loads to the simply supported beam type soil pressure sensor span step by step to obtain the strain of the middle and lower edges of the simply supported beam type soil pressure sensor span, and obtaining the linear slope of the concentrated loads acting on the simply supported beam type soil pressure sensor span and the strain of the middle and lower edges of the simply supported beam type soil pressure sensor span;
s3: acquiring a sandy soil internal friction angle of a simply supported beam type soil pressure sensor embedding position;
s4: acquiring a strain response value of a simply supported beam type soil pressure sensor buried in a soil body under the action of soil pressure;
s5: the soil pressure strength borne by the simply supported beam type soil pressure sensor is calibrated according to the width of a simply supported plate of the simply supported beam type soil pressure sensor, the net span length of the simply supported plate of the simply supported beam type soil pressure sensor, the concentrated load acting in the simply supported beam type soil pressure sensor, the linear slope of the strain of the middle and lower edges of the simply supported beam type soil pressure sensor, the sandy soil internal friction angle of the embedding position of the simply supported beam type soil pressure sensor and the strain response value of the simply supported beam type soil pressure sensor embedded in a soil body under the action of soil pressure.
In the embodiment of the present invention, in step S2, a specific method for acquiring the gradient of the concentrated load acting in the simply supported beam type soil pressure sensor span and the strain straight line of the mid-span lower edge of the corresponding simply supported beam type soil pressure sensor span includes: and taking the concentrated load acting in the simply-supported beam type soil pressure sensor span as a vertical coordinate, taking the strain of the middle lower edge of the corresponding simply-supported beam type soil pressure sensor span as a horizontal coordinate, and performing linear fitting to obtain the linear slope of the concentrated load acting in the simply-supported beam type soil pressure sensor span and the strain of the middle lower edge of the corresponding simply-supported beam type soil pressure sensor span.
In the embodiment of the invention, in step S3, the sandy soil internal friction angle of the burying position of the simply supported beam type soil pressure sensor is obtained through a soil test.
In the embodiment of the present invention, in step S5, the calculation formula of the soil pressure strength p borne by the simply supported beam type soil pressure sensor is:
wherein b represents the width of the simply supported plate of the simply supported beam type soil pressure sensor, and l 0 Representing the net span length of a simple beam earth pressure sensor,
the method comprises the steps of representing a sandy soil internal friction angle of a simply supported beam type soil pressure sensor burying position, representing a strain response value of the simply supported beam type soil pressure sensor buried in a soil body under the action of soil pressure, and representing a linear slope of a concentrated load acting in a simply supported beam type soil pressure sensor span and strain of a corresponding middle lower edge of the simply supported beam type soil pressure sensor span.
Simply supported plate width b and clear span length l of simply supported beam type soil pressure sensor 0 The unit is m; concentrated load F acting on span of simply-supported beam type soil pressure sensor in process of acquiring slope alpha of straight line i The unit is N, and the strain epsilon of the mid-span lower edge of the corresponding simply supported beam type soil pressure sensor i Unit is 10 -6 (ii) a The unit of the strain response value epsilon is 10 -6 (ii) a Internal friction angle of sandy soil
Unit of (d) is °; the unit of the soil pressure strength p is pa.
In the embodiment of the invention, the calibration method is suitable for the range of the internal friction angle
The sandy soil of (1).
The principle of the method of the invention is described below: the calibration of the simply supported beam type soil pressure sensor is realized by applying concentrated force in the span of the simply supported beam plate, and the acting force born by the actual soil pressure sensor is distributed load and must be converted by adopting a reasonable method, so the calibration is carried out based on the following principle:
(a) The stress mode of the simply supported beam type soil pressure sensor is a simply supported beam;
(b) Concentrated loadThe strain of the sensor mid-span lower edge is the same as that of the sensor mid-span lower edge generated under the action of distributed load, namely the mid-span bending moment M generated by the sensor under the action of concentrated load F And the midspan bending moment M under the action of distributed load q Equal, M F ＝M q ；
(c) Considering the soil arch effect, the soil pressure acting on the sensor is in a non-uniform distribution mode, and the specific distribution mode changes along with different strength of sandy soil.
1. Non-uniform distribution mode and equivalent uniform distribution strength p of soil pressure of sandy soil acting on sensor in loose state
By using
The loose sandy soil is subjected to a calibration test, the soil pressure acting on the sensor is approximately in a symmetrical zigzag non-uniform distribution mode as shown in figure 2, and the midspan soil pressure is about half of the soil pressure q on two sides.
(1) Based on principle (a), concentrated load F acts on bending moment in span
Midspan bending moment under action of symmetrical polygonal line-shaped non-uniformly distributed load
(2) From principle (b), M F ＝M q To obtain
(3) The resultant force of the equivalent equipartition soil pressure intensity p acting on the sensor is equal to the resultant force of the symmetrical fold-line shaped unevenly distributed load, i.e.
Soil pressure strength measured by simply supported beam type soil pressure sensor
2. Non-uniform distribution mode of soil pressure and equivalent uniform distribution strength p of sandy soil acting on sensor in medium-density state
By using
The sandy soil in the medium density state is subjected to a calibration test, the soil pressure acting on the sensor is approximately in a symmetrical triangular non-uniform distribution mode as shown in figure 3, and the cross-soil pressure is 0.
(1) Based on principle (a), concentrated load F acts on bending moment in span
Midspan bending moment under action of symmetrical triangular non-uniformly distributed load
(2) From principle (b), M F ＝M q To obtain
(3) The resultant force of the equivalent equipartition soil pressure intensity p acting on the sensor is equal to the resultant force of the symmetrical triangular non-uniformly distributed load, i.e.
Soil pressure strength measured by simply supported beam type soil pressure sensor
3. Non-uniform distribution mode of soil pressure and equivalent uniform distribution strength p of sandy soil acting on sensor in compact state
By using
The dense sandy soil is subjected to a calibration test, the soil pressure acting on the sensor is approximately in a symmetrical parabolic non-uniform distribution mode as shown in figure 4, and the cross-middle soil pressureThe force is 0, if the coordinate system is established with the midspan as the origin, the parabolic equation is
(1) Based on principle (a), concentrated load F acts on bending moment in span
Midspan bending moment under action of symmetrical parabola non-uniformly distributed load
(2) From principle (b), M F ＝M q To obtain
(3) The resultant force of the equivalent equipartition soil pressure intensity p acting on the sensor is equal to the resultant force of the symmetrical parabola non-uniformly distributed load, i.e.
Soil pressure strength measured by simply supported beam type soil pressure sensor
In summary, the earth pressure intensity p can be expressed by the formula for sandy soils with different intensities
And (4) calculating to determine the size of the coefficient beta according to the strength of the soil arching effect.
β =2.25;
when, β =3;
when β =4. Taking the beta as a dependent variable, and taking the beta as a dependent variable,
linear fitting is carried out on independent variables to obtain a relation formula of the independent variables and the independent variables
Determining the coefficient R 2 =0.995,. Beta.and
In a linear relationship. Therefore, the simple beam type soil pressure sensor can adopt a formula
And (5) calibrating.
Through analysis and tests, the soil pressure borne by the sensor is in a non-uniform distribution mode due to the soil arch effect, and the soil arch effect is enhanced along with the increase of the soil body strength. However, in the prior art, the calibration method of the simply supported beam type soil pressure sensor considers the soil pressure according to an even distribution mode, and ignores the soil arch effect of the interaction between the sensor and the soil body. The test results of the method of the present invention for calibrating the pressure of the sandy soil wall against the soil are given below.
Obtaining the width b and the clear span length l of a simply supported beam type soil pressure sensor through an indoor soil test 0 Concentrated load F acting on span of simply supported beam type soil pressure sensor i Corresponding mid-span lower edge strain epsilon i Linear slope alpha, and sandy soil internal friction angle of soil pressure sensor burying position
And the strain response value epsilon of the simply supported beam type soil pressure sensor under the action of soil pressure. The soil pressure strength p calibrated by the method of the present invention, the soil pressure strength p 'calibrated according to the prior art and the theoretically calculated value p' are different, as shown in Table 1.
TABLE 1
As can be seen from the above, the deviations of the soil pressure strength p of M1 to M3 calibrated by the method of the invention from the theoretical calculation value p' are only 4.77%, -3.52% and 1.82%, respectively, and the average is 3.37%. The deviations of the soil pressure strength p 'of M1-M3 determined by the calibration method of the prior art and the theoretical value p' are respectively-6.87%, -35.68% and-49.09%, and the average deviation is smaller than 30.55%. The method has high test precision and good reliability, and solves the technical problem of soil pressure test in the prior art that the influence of soil arching effect is not well considered.
The invention has the beneficial effects that: the method not only considers the non-uniform distribution of the soil pressure caused by the soil arching effect, but also obtains the soil pressure calibration formula of the sensor suitable for different soil body strengths according to the difference of the soil arching effect. The soil pressure tested by the method is verified with a theoretical calculated value, and the relative error is very small, which shows that the method has high test precision and good reliability, solves the technical problem of soil pressure test that the influence of soil arching effect is not well considered in the prior art, can test the soil pressure more accurately, and reduces the deviation caused by the soil arching effect.
It will be appreciated by those of ordinary skill in the art that the embodiments described herein are intended to assist the reader in understanding the principles of the invention and are to be construed as being without limitation to such specifically recited embodiments and examples. Those skilled in the art can make various other specific changes and combinations based on the teachings of the present invention without departing from the spirit of the invention, and these changes and combinations are within the scope of the invention.
Claims (4)
1. A calibration method of a simply supported beam type soil pressure sensor is characterized by comprising the following steps:
s1: measuring the width and the clear span length of a simply supported plate of the simply supported beam type soil pressure sensor;
s2: gradually applying a concentrated load to the span of the simply supported beam type soil pressure sensor step by step, acquiring the strain of the middle lower edge of the corresponding simply supported beam type soil pressure sensor span, and acquiring the linear slope of the concentrated load acting on the span of the simply supported beam type soil pressure sensor and the strain of the middle lower edge of the corresponding simply supported beam type soil pressure sensor span;
s3: acquiring a sandy soil internal friction angle of a burying position of a simply supported beam type soil pressure sensor;
s4: acquiring a strain response value of a simply supported beam type soil pressure sensor buried in a soil body under the action of soil pressure;
s5: calibrating the soil pressure strength born by the simply supported beam type soil pressure sensor according to the width of the simply supported plate of the simply supported beam type soil pressure sensor, the net span length of the simply supported plate of the simply supported beam type soil pressure sensor, the concentrated load acting in the simply supported beam type soil pressure sensor, the linear slope of the strain of the middle and lower edges of the simply supported beam type soil pressure sensor, the sandy soil internal friction angle of the embedding position of the simply supported beam type soil pressure sensor and the strain response value of the simply supported beam type soil pressure sensor embedded in a soil body under the action of soil pressure;
in the step S5, a calculation formula of the soil pressure strength p borne by the simply supported beam type soil pressure sensor is as follows:
wherein b represents the width of the simply supported plate of the simply supported beam type soil pressure sensor, l 0 Representing the net span length of a simple beam earth pressure sensor,
the method comprises the steps of representing a sandy soil internal friction angle of a simply supported beam type soil pressure sensor burying position, representing a strain response value of the simply supported beam type soil pressure sensor buried in a soil body under the action of soil pressure, and representing a linear slope of a concentrated load acting in a simply supported beam type soil pressure sensor span and strain of a corresponding middle lower edge of the simply supported beam type soil pressure sensor span.
2. The method for calibrating the simply supported beam type soil pressure sensor according to claim 1, wherein in the step S2, the specific method for acquiring the concentrated load acting in the simply supported beam type soil pressure sensor span and the slope of the strain straight line of the corresponding simply supported beam type soil pressure sensor span middle and lower edge is as follows: and taking the concentrated load acting in the simply-supported beam type soil pressure sensor span as a vertical coordinate, taking the strain of the middle lower edge of the corresponding simply-supported beam type soil pressure sensor span as a horizontal coordinate, and performing linear fitting to obtain the linear slope of the concentrated load acting in the simply-supported beam type soil pressure sensor span and the strain of the middle lower edge of the corresponding simply-supported beam type soil pressure sensor span.
3. The method for calibrating the SIMOX cantilever beam type soil pressure sensor as recited in claim 1, wherein in the step S3, the internal friction angle of sandy soil at the embedded position of the SIMOX cantilever beam type soil pressure sensor is obtained through a soil test.
4. The method for calibrating a SIMILAR BEAM-TYPE EARTH PRESSURE SENSOR as recited in claim 1, wherein said method is adapted for use in a range of internal friction angles
The sandy soil.
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