Deformation and strength determination method of rubber particle mixed sand under cyclic load effect

Abstract

The invention belongs to the technical field of pavement and roadbed detection, and particularly relates to a method for determining deformation and strength of rubber particle mixed sand under cyclic loading, which comprises the following steps: firstly, preparing a test material and a sample, and completing installation and saturation of the sample; then a strength measuring device is used for conducting dynamic and static triaxial measurement on the test material and the sample under different measuring conditions, and the specific steps are as follows: firstly, the confining pressure and the back pressure are adjusted to a preset confining pressure value sigma3 and a preset back pressure value P0 through a confining pressure controller and a back pressure controller; when each group of confining pressure and back pressure reaches a test target value, applying a dynamic load or a static load through the upper computer; and finally, the upper computer processes the data acquired by each sensor, and outputs each group of measurement data generated in the test process by identifying the difference value between the actual value and the target value in the test process. By arranging the strength measuring device, the basic characteristic parameters of the waste tire rubber particle and sandy soil mixed sample can be accurately measured.

Description

Technical Field

[0001] The invention belongs to the technical field of road surface and subgrade detection, and in particular relates to a method for measuring deformation and strength of rubber particle mixed sand under cyclic load. Background Art

[0002] With the rapid growth of the number of cars in recent years, the number of waste tires generated during the use of cars has also increased. Waste tires are called black pollution, which will cause serious damage to the natural environment, so how to recycle and treat waste tires in an environmentally friendly and effective manner has become a difficult problem that countries around the world need to face; at present, the use of waste tires in the field of roadbed reinforcement has been effectively promoted after crushing them into particles; waste tire particles mixed with sand have been widely used in the field of civil engineering construction due to their light weight, strong permeability, high elasticity and low cost; especially the use of waste tire particles in roadbed engineering can not only reduce the amount of sand and soil used, but also improve the stability of the roadbed under cyclic loads, so it is necessary to mix rubber particles with rubber particles. The strength of the mixed sand roadbed is measured. In the existing roadbed strength measurement method, a Beckmann beam deflection meter is usually used for detection. The dial indicator bracket of the Beckmann beam deflection meter is close to the deflection area, so that the dial indicator and the detection head are both in the deflection area, resulting in deviations in the data of the dial indicator, thereby reducing the accuracy of the Beckmann beam deflection meter detection. The measurement method of the existing technology is only applicable to the traditional roadbed strength measurement. For the roadbed made of waste tire particles mixed with sand, the detection accuracy needs to be improved. For this reason, we propose a deformation and strength measurement method for rubber particle mixed sand under cyclic load. Summary of the invention

[0003] The purpose of the present invention is to provide a method for measuring the deformation and strength of rubber particle mixed sand under cyclic load. First, the test material and the sample are prepared, and the sample is installed and saturated; then, a strength measuring device is used to perform dynamic and static triaxial measurements on the test material and the sample under different measurement conditions. The specific steps are as follows: first, the confining pressure and the back pressure are adjusted to a pre-set confining pressure value σ by a confining pressure controller and a back pressure controller. 3 and back pressure value P 0; When each group of confining pressure and reverse pressure reaches the test target value, the host computer will apply dynamic load or static load by controlling force or displacement; finally, the host computer will process the data collected by each sensor according to the set calculation mode, and the host computer will output each group of measurement data generated during the test by identifying the difference between the actual value and the target value during the test. In summary, by setting up a strength measurement device and adopting the GDS dynamic triaxial instrument experimental principle, the strength measurement of the mixed roadbed of rubber particles made of waste tires and sand is completed. The axial force, axial strain, radial strain, effective consolidation confining pressure, consolidation ratio and deviatoric stress of the mixed roadbed can be accurately measured, and finally the basic characteristic parameters of the mixed sample of waste tire rubber particles and sand can be accurately measured, so that the detection accuracy is higher.

[0004] The technical solution adopted by the present invention is as follows:

[0005] The method for determining the deformation and strength of rubber granule mixed sand under cyclic loading comprises the following steps:

[0006] Step 1: Set up the strength measurement device;

[0007] Step 2: Prepare test materials and specimens, and complete the installation and saturation of the specimens;

[0008] Step 3: Use the strength measuring device to perform dynamic and static triaxial tests on the test materials and specimens under different test conditions. The specific steps are as follows:

[0009] Step 301: Specifically, the confining pressure and the back pressure are adjusted to a preset confining pressure value σ by a confining pressure controller and a back pressure controller. 3 and back pressure value P 0 ,

[0010] Step 302: When the confining pressure and reverse pressure of each group reach the test target value, the host computer applies a dynamic load or a static load by controlling the force or the displacement;

[0011] Step 303: The host computer processes the data collected by each sensor according to the set calculation mode. The host computer outputs each group of measurement data generated during the test by identifying the difference between the actual value and the target value during the test.

[0012] Preferably, the strength measuring device includes a data acquisition component, an external control component and a host computer; the external control component includes an axial force controller, a pressure chamber, a confining pressure controller, and a back pressure controller; the data acquisition component includes a signal receiver, an axial force sensor, and a pore water pressure sensor.

[0013] Preferably, a pressure cover is provided on the pressure chamber, the axial force sensor is installed on the top of the pressure cover, and the pore water pressure sensor is installed on the side of the pressure cover.

[0014] Preferably, the axial force controller, the confining pressure controller and the back pressure controller are all connected to the pressure hood.

[0015] Preferably, the host computer is electrically connected to the confining pressure controller, the back pressure controller, the axial force controller, the pressure chamber and the signal receiver, and the signal receiver is electrically connected to the axial force sensor and the pore water pressure sensor.

[0016] Preferably, in step 2, a dry density control method is used to prepare the sample ratio during the preparation of the rubber mixed sand sample; when different contents of rubber particles are added to the sand particles, the dry density of the sand in the rubber mixed sand sample is always equal to the dry density of the pure sand sample; the ratio calculation formula is shown in the following formula:

[0017]

[0018] Where: V o Represents the total volume of rubber mixed with sand; V x Indicates the volume of rubber; V S Represents the volume of sand; V k represents the pore volume between particles; M o Indicates the total mass of the sample; M S Indicates the mass of sand particles; M x Indicates the mass of rubber particles.

[0019] Preferably, in step 2, before installing the sample, the mixed rubber sand is loaded by wet loading method, the rubber sand mixed particles weighed according to the ratio are boiled with water and cooled for 12 hours for use; then the strength measuring point is tested to see if the device is normal.

[0020] Preferably, during the sample installation process in step 2, a permeable stone is placed on the base of the pressure cover, and a soaked filter paper is placed on the permeable stone; after the three-petal mold is installed, the rubber sand particles are started to be filled; the boiled and cooled mixed sand and soil are loaded into the rubber membrane; after the loading is completed, the back pressure is set to -30kPa, and the three-petal mold is removed after the back pressure loading is stable, and the outer pressure cover is covered and filled with water and the axial force sensor value is set to 0.005KN. At this time, the base of the pressure cover will rise and contact the top sensor. When the axial force reaches 0.005kN, the base of the pressure cover will no longer rise, and the exhaust hole plug on the top of the pressure chamber is opened, and the water inlet valve is opened to fill the pressure chamber with water. After filling, the inlet valve and the exhaust hole plug are closed.

[0021] Preferably, in the process of saturating the sample in step 2, the sample is saturated by the water head saturation and back pressure saturation methods. First, water head saturation is performed; the drain valve of the pressure shield base is connected to the drain valve of the water container; the container drain valve is opened, so that the distilled water after boiling and cooling will flow from the pressure shield base into the bottom of the sample, the water will fill some of the pores between the sample particles and discharge the air in the sample, the saturation of the sample will gradually increase, and finally the distilled water will flow out from the top of the sample into a container prepared in advance.

[0022] Back pressure saturation: The air in the sample can be dissolved into the water by applying five levels of back pressure saturation. The back pressure saturation is completed after the five levels of back pressure loading are completed.

[0023] Preferably, in step 3, the initial diameter D0 and initial height H0 of the triaxial specimen are assumed; the formula for calculating the initial area A0 and volume V0 of the specimen is as follows:

[0024]

[0025] In the dynamic triaxial test, the diameter of the specimen is D, the height is H, and the area and volume are A and V respectively; it can be concluded that the volume change of the specimen is △V=V0-V, and the back pressure controller is connected to the specimen, so the change of dynamic pore water pressure is related to the volume change of water in the back pressure controller, that is, the volume change data of the back pressure controller is the data change of pore water pressure, and there is also the following derivation formula; actual specimen axial force: σ=F / A+σ3; effective stress derived from pore water pressure: σ'3=σ3-u w ; Effective axial stress: σ'=σ-u w ; Axial strain: ε a =(△H / H0)×100%; radial strain:

[0026] ε r =[(-D+D0) / D0]×100%; effective consolidation confining pressure σ'3 and consolidation ratio K c The deviatoric stress is obtained as follows: σ1=σ'3×K c -σ'3.

[0027] The technical effects achieved by the present invention are:

[0028] In the present invention, the test material and the sample are first prepared, and the sample is installed and saturated; then, a strength measuring device is used to perform dynamic and static triaxial tests on the test material and the sample under different test conditions. The specific steps are as follows: first, the confining pressure and the back pressure are adjusted to a pre-set confining pressure value σ by a confining pressure controller and a back pressure controller. 3 and back pressure value P 0; When each group of confining pressure and reverse pressure reaches the test target value, the host computer will apply dynamic load or static load by controlling force or displacement; finally, the host computer will process the data collected by each sensor according to the set calculation mode, and the host computer will output each group of measurement data generated during the test by identifying the difference between the actual value and the target value during the test. In summary, by setting up a strength measurement device and adopting the GDS dynamic triaxial instrument experimental principle, the strength measurement of the mixed roadbed of rubber particles made of waste tires and sand is completed. The axial force, axial strain, radial strain, effective consolidation confining pressure, consolidation ratio and deviatoric stress of the mixed roadbed can be accurately measured, and finally the basic characteristic parameters of the mixed sample of waste tire rubber particles and sand can be accurately measured, so that the detection accuracy is higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a flow chart of the method for measuring deformation and strength of rubber particle mixed sand under cyclic load of the present invention;

[0030] Figure 2 It is a system block diagram of a measuring device in a method for measuring deformation and strength of rubber particle mixed sand under cyclic load of the present invention;

[0031] Figure 3 The present invention is a five-level back pressure loading change curve diagram;

[0032] Figure 4 The present invention is a flow chart of the use of a measuring device in a method for measuring deformation and strength of rubber particle mixed sand under cyclic load. DETAILED DESCRIPTION

[0033] In order to make the objects and advantages of the present invention more clearly understood, the present invention is specifically described below in conjunction with embodiments; it should be understood that the following text is only used to describe one or several specific implementations of the present invention, and does not strictly limit the scope of protection specifically requested by the present invention.

[0034] like Figure 1 As shown, the method for determining the deformation and strength of rubber particle mixed sand under cyclic load comprises the following steps:

[0035] Step 1: Set up the strength measurement device;

[0036] Step 2: Prepare test materials and specimens, and complete the installation and saturation of the specimens;

[0037] Step 3: Use the strength measuring device to perform dynamic and static triaxial tests on the test materials and specimens under different test conditions, such as Figure 4 As shown, the specific steps are as follows:

[0038] Step 301: Specifically, the confining pressure and the back pressure are adjusted to a preset confining pressure value σ by a confining pressure controller and a back pressure controller. 3 and back pressure value P 0 ,

[0039] Step 302: When the confining pressure and reverse pressure of each group reach the test target value, the host computer applies a dynamic load or a static load by controlling the force or the displacement;

[0040] Step 303: The host computer processes the data collected by each sensor according to the set calculation mode. The host computer outputs each group of measurement data generated during the test by identifying the difference between the actual value and the target value during the test.

[0041] In the present invention, by setting a strength measuring device and adopting the GDS dynamic triaxial instrument experimental principle, the strength measurement of the mixed roadbed of rubber particles made of waste tires and sand is completed, and the axial force, axial strain, radial strain, effective consolidation confining pressure, consolidation ratio and deviatoric stress of the mixed roadbed can be accurately measured, and finally the basic characteristic parameters of the mixed sample of waste tire rubber particles and sand are accurately measured, so that the detection accuracy is higher.

[0042] like Figure 2 As shown, the strength measuring device includes a data acquisition component, an external control component and a host computer; the external control component includes an axial force controller, a pressure chamber, a confining pressure controller and a back pressure controller; the data acquisition component includes a signal receiver, an axial force sensor and a pore water pressure sensor; a pressure cover is provided on the pressure chamber, the axial force sensor is installed on the top of the pressure cover, and the pore water pressure sensor is installed on the side of the pressure cover; the axial force controller, the confining pressure controller and the back pressure controller are all connected to the pressure cover; the host computer is electrically connected to the confining pressure controller, the back pressure controller, the axial force controller, the pressure chamber and the signal receiver, and the signal receiver is electrically connected to the axial force sensor and the pore water pressure sensor.

[0043] In the present invention, Figure 2 As shown, the host computer directly uses a computer, and GDSLAP software runs inside the computer. Data processing is completed through the GDSLAP software, thereby improving the accuracy of the measurement results.

[0044] In step 2, the dry density control method is used to prepare the sample ratio in the process of preparing the rubber mixed sand sample; when different contents of rubber particles are added to the sand particles, the dry density of the sand in the rubber mixed sand sample is always equal to the dry density of the pure sand sample; the ratio calculation formula is shown in the following formula:

[0045]

[0046] Where: V o Represents the total volume of rubber mixed with sand; Vx Indicates the volume of rubber; V S Represents the volume of sand; V k represents the pore volume between particles; M o Indicates the total mass of the sample; M S Indicates the mass of sand particles; M x Indicates the mass of rubber particles.

[0047] In the present invention, a dry density control method is adopted to carry out sample preparation and proportioning in the process of preparing rubber mixed sand samples, so as to ensure that the arrangement properties of sand particles in each group of samples are consistent, thereby ensuring that when the test method tests rubber mixed sand samples with different proportions, the results can guarantee a certain degree of accuracy.

[0048] Step 2 Before installing the sample, use the wet loading method to load the mixed rubber sand. Add water to the rubber sand mixed particles weighed according to the ratio and boil them. After cooling for 12 hours, set them aside. Then test the strength to determine whether the device is normal.

[0049] It should be noted that during the test strength determination process, first check whether the equipment is plugged in and working normally, turn on the DCS controller and the confining pressure and back pressure controllers; then open the valves connecting the pressure cover to the sample, including the orifice pressure valve, drain valve, confining pressure valve and back pressure valve, and pass water into each pipe to check whether the drainage pipe is blocked.

[0050] In the present invention, before measuring, the equipment is checked to avoid measuring errors and improve the measuring accuracy.

[0051] Step 2 During the sample installation process, place a permeable stone on the base of the pressure cover, and then place a soaked filter paper on the permeable stone; after installing the three-petal mold, start filling the rubber sand particles; slowly load the boiled and cooled mixed sand and soil into the rubber membrane; the loading process should be uniform and slow; after the loading is completed, set the back pressure to -30kPa, and remove the three-petal mold after the back pressure loading is stable. At this time, the sample can be in an upright state due to the negative pressure; cover the outer pressure cover, fill it with water and set the axial force sensor value to 0.005KN. At this time, the base of the pressure cover will rise and contact the top sensor. When the axial force reaches 0.005kN, the base of the pressure cover will no longer rise, and the sample will contact the axial force sensor; open the vent plug on the top of the pressure chamber, open the water inlet valve to fill the pressure chamber with water, and close the inlet valve and vent plug after filling.

[0052] Step 2: During the sample saturation process, the sample is saturated using the head saturation and back pressure saturation methods to increase the saturation of the mixed sand sample; the sample saturation is performed in two steps, firstly, the head saturation is performed; the drain valve of the pressure shield base is connected to the drain valve of the water container; the container drain valve is opened, so that the distilled water after boiling and cooling will flow from the pressure shield base into the bottom of the sample, the water will fill some of the pores between the sample particles and discharge the air in the sample, the saturation of the sample will gradually increase, and finally the distilled water will flow out from the top of the sample into the container prepared in advance.

[0053] Back pressure saturation: After the water head saturation in the previous step, a small amount of air will remain inside the sample. By applying five levels of back pressure saturation, the air in the sample can be dissolved in the water. Figure 3 It is a curve diagram of the five-level back pressure loading change; the effective confining pressure is always maintained at 20kPa during the back pressure loading process; the confining pressure is set to be greater than the back pressure in order to prevent the dynamic pore pressure inside the specimen from being overloaded and causing damage to the specimen. The five-level loading process can minimize the disturbance of the test pressure hood loading on the specimen; the back pressure saturation is completed after the five-level back pressure loading is completed.

[0054] In step 3, the initial diameter D0 and initial height H0 of the triaxial specimen are assumed; the formula for calculating the initial area A0 and volume V0 of the specimen is as follows:

[0055]

[0056] In the dynamic triaxial test, the diameter of the specimen is D, the height is H, and the area and volume are A and V respectively; it can be concluded that the volume change of the specimen is △V=V0-V. The back pressure controller of the test pressure cover is connected to the specimen, so the change of dynamic pore water pressure is related to the volume change of water in the back pressure controller, that is, the volume change data of the back pressure controller is the data change of pore water pressure, and the following derivation formula is also available; actual specimen axial force: σ=F / A+σ3; effective stress derived from pore water pressure: σ'3=σ3-u w ; Effective axial stress: σ'=σ-u w ; Axial strain: ε a =(△H / H0)×100%; radial strain: ε r =[(-D+D0) / D0]×100%; effective consolidation confining pressure σ'3 and consolidation ratio K c The deviatoric stress is obtained as follows: σ1=σ'3×K c -σ'3.

[0057] In the present invention, the test material and the sample are first prepared, and the sample is installed and saturated; then, a strength measuring device is used to perform dynamic and static triaxial tests on the test material and the sample under different test conditions. The specific steps are as follows: first, the confining pressure and the back pressure are adjusted to a pre-set confining pressure value σ by a confining pressure controller and a back pressure controller.3 and back pressure value P 0 ; When each group of confining pressure and reverse pressure reaches the test target value, the host computer will apply dynamic load or static load by controlling force or displacement; finally, the host computer will process the data collected by each sensor according to the set calculation mode, and the host computer will output each group of measurement data generated during the test by identifying the difference between the actual value and the target value during the test. In summary, by setting up a strength measurement device and adopting the GDS dynamic triaxial instrument experimental principle, the strength measurement of the mixed roadbed of rubber particles made of waste tires and sand is completed. The axial force, axial strain, radial strain, effective consolidation confining pressure, consolidation ratio and deviatoric stress of the mixed roadbed can be accurately measured, and finally the basic characteristic parameters of the mixed sample of waste tire rubber particles and sand can be accurately measured, so that the detection accuracy is higher.

[0058] The above are only preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications should also be considered as the protection scope of the present invention. The structures, devices and operating methods not specifically described and explained in the present invention shall be implemented according to conventional means in the art unless otherwise specified and limited.

Claims

1. A method for determining the deformation and strength of rubber granule mixed sand under cyclic loading, characterized in that: The following steps are involved: Step 1: Set up the strength measurement device; Step 2: Prepare test materials and specimens, and complete the installation and saturation of the specimens; Step 3: Use the strength measuring device to perform dynamic and static triaxial tests on the test materials and specimens under different test conditions. The specific steps are as follows: Step 301: Adjust the confining pressure and the back pressure to a preset confining pressure value σ through the confining pressure controller and the back pressure controller. 3 and back pressure value P 0 , Step 302: When the confining pressure and reverse pressure of each group reach the test target value, the host computer applies a dynamic load or a static load by controlling the force or the displacement; Step 303: The host computer processes the data collected by each sensor according to the set calculation mode. The host computer outputs each group of measurement data generated during the test by identifying the difference between the actual value and the target value during the test.

2. The method for measuring deformation and strength of rubber particle mixed sand under cyclic load according to claim 1, characterized in that: The strength measuring device includes a data acquisition component, an external control component and a host computer; the external control component includes an axial force controller, a pressure chamber, a confining pressure controller, and a back pressure controller; the data acquisition component includes a signal receiver, an axial force sensor, and a pore water pressure sensor.

3. The method for measuring deformation and strength of rubber particle mixed sand under cyclic load according to claim 2, characterized in that: A pressure cover is provided on the pressure chamber, the axial force sensor is installed on the top of the pressure cover, and the pore water pressure sensor is installed on the side of the pressure cover.

4. The method for measuring deformation and strength of rubber particle mixed sand under cyclic load according to claim 3, characterized in that: The axial force controller, the confining pressure controller and the back pressure controller are all connected to the pressure cover.

5. The method for measuring deformation and strength of rubber particle mixed sand under cyclic load according to claim 4, characterized in that: The host computer is electrically connected to the confining pressure controller, the back pressure controller, the axial force controller, the pressure chamber and the signal receiver, and the signal receiver is electrically connected to the axial force sensor and the pore water pressure sensor.

6. The method for measuring deformation and strength of rubber particle mixed sand under cyclic load according to claim 5, characterized in that: In the step 2, a dry density control method is used to prepare the sample ratio during the preparation of the rubber mixed sand sample; when different contents of rubber particles are added to the sand particles, the dry density of the sand in the rubber mixed sand sample is always equal to the dry density of the pure sand sample; The formula for calculating the ratio is as follows: Where: V o Represents the total volume of rubber mixed with sand; V x Indicates the volume of rubber; V S V represents the volume of sand; k represents the pore volume between particles; M o Indicates the total mass of the sample; M S Indicates the mass of sand particles; M x Indicates the mass of rubber particles.

7. The method for measuring deformation and strength of rubber particle mixed sand under cyclic load according to claim 6, characterized in that: In step 2, before installing the sample, the mixed rubber sand is loaded by wet loading method, the rubber sand mixed particles weighed according to the proportion are boiled with water and cooled for 12 hours for use; then the strength measuring point is tested to see if the device is normal.

8. The method for measuring deformation and strength of rubber particle mixed sand under cyclic load according to claim 7, characterized in that: In the step 2, during the sample installation process, a permeable stone is placed on the base of the pressure cover, and a soaked filter paper is placed on the permeable stone; after the three-petal mold is installed, rubber sand particles are started to be filled; the boiled and cooled mixed sand and soil are loaded into the rubber membrane; after the sample loading is completed, the back pressure is set to -30kPa, and after the back pressure loading is stable, the three-petal mold is removed, the outer pressure cover is covered and filled with water, and the axial force sensor value is set to 0.005KN, at which time the pressure cover base will rise and contact the top sensor, and when the axial force reaches 0.005kN, the pressure cover base will no longer rise, open the exhaust hole plug on the top of the pressure chamber, open the water inlet valve to fill the pressure chamber with water, and close the inlet valve and the exhaust hole plug after filling.

9. The method for measuring deformation and strength of rubber particle mixed sand under cyclic load according to claim 8, characterized in that: In the step 2, during the sample saturation process, the sample is saturated by the water head saturation and back pressure saturation methods. First, the water head saturation is performed; the pressure shield base drain valve is connected to the water container drain valve; the container drain valve is opened, so that the distilled water after boiling and cooling will flow from the pressure shield base into the bottom of the sample, the water will fill part of the pores between the sample particles and discharge the air in the sample, the saturation of the sample will gradually increase, and finally the distilled water will flow out from the top of the sample into the container prepared in advance; Back pressure saturation: The air in the sample can be dissolved into the water by applying five levels of back pressure saturation. The back pressure saturation is completed after the five levels of back pressure loading are completed.

10. The method for measuring deformation and strength of rubber particle mixed sand under cyclic load according to claim 9, characterized in that: In step 3, the initial diameter D0 and initial height H0 of the triaxial specimen are assumed; the formula for calculating the initial area A0 and volume V0 of the specimen is as follows: In the dynamic triaxial test, the diameter of the specimen is D, the height is H, and the area and volume are A and V respectively; it can be concluded that the volume change of the specimen is △V=V0-V. The back pressure controller is connected to the specimen, so the change of dynamic pore water pressure is related to the volume change of water in the back pressure controller, that is, the volume change data of the back pressure controller is the data change of pore water pressure, and the following derivation formula is also available; actual specimen axial force: σ=F / A+σ3; effective stress is derived from pore water pressure: σ'3=σ3-u w ; Effective axial stress: σ'=σ-u w ; Axial strain: ε a =(△H / H0)×100%; radial strain: ε r =[(-D+D0) / D0]×100%; effective consolidation confining pressure σ'3 and consolidation ratio K c The deviatoric stress is obtained as follows: σ1=σ'3×K c -σ'3.

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