CN108535113B - A Comprehensive Determination Method for Deformation Parameters of Horizontally Layered Rock Mass - Google Patents

Abstract

The invention relates to a method for comprehensively determining deformation parameters of a horizontally layered rock mass, and belongs to the technical field of rock mass deformation parameter testing. The method is carried out in a test hole at the construction site, and includes the following steps: 1), preparing test components, selecting a test position in the test hole, and preparing for the field test; 2), carrying out layered rock samples in the test hole 3) Carry out the vertical bearing plate test and the horizontal bearing plate test in the test hole and record the data and pressure ～Drawing the deformation curve; 4) According to the uniaxial test results of the layered rock mass and the pressure-deformation curve of the vertical bearing plate test and the horizontal bearing plate test, use the commercial finite element calculation program to carry out numerical inverse analysis, and finally determine Five deformation indexes that reflect the transverse isotropy of the horizontal layered rock mass; 5), determine the elastic modulus of the layered rock mass in combination with the field rock structure investigation results and empirical formulas to verify the rock mass deformation index determined earlier. The invention is a comprehensive determination method of deformation parameters of horizontal layered rock mass.

Description

A Comprehensive Determination Method for Deformation Parameters of Horizontally Layered Rock Mass

technical field

The invention relates to a method for comprehensively determining deformation parameters of a horizontally layered rock mass, and belongs to the technical field of rock mass deformation parameter testing.

Background technique

Layered rock mass is often encountered in tunnel or roadway construction. Different from homogeneous rock mass, the mechanical properties of layered rock mass are significantly anisotropic, and there are many independent variables of rock mass deformation parameters, which are difficult to measure. At present, there is no method that can accurately measure the deformation parameters of layered rock mass, which can provide reliable basic data for the engineering design and construction of layered rock mass.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a comprehensive method for determining the deformation parameters of horizontal layered rock mass based on the combination of rock mass uniaxial compression test, field rigid bearing plate test and numerical inversion,

In order to achieve the above object, the technical scheme adopted in the present invention is:

A method for comprehensively determining deformation parameters of a horizontally layered rock mass, the method is carried out in a test cave at a construction site, and includes the following steps:

1) Prepare the test components, select the test position in the test hole, and prepare for the field test;

2) Carry out the uniaxial compression test of the layered rock samples in the test cave, record the axial pressure-deformation curve, the axial deformation-lateral deformation curve, and determine the vertical elastic modulus and Poisson of the horizontal layered rock mass. Compare;

3), in the test hole vertical bearing plate test and horizontal bearing plate test and record the data and draw the pressure-deformation curve;

4) According to the uniaxial test results of the layered rock mass and the pressure-deformation curve of the vertical bearing plate test and the horizontal bearing plate test, use the finite element calculation program to carry out numerical inverse analysis, and finally comprehensively determine the reaction of the horizontal layered rock mass 5 deformation indexes of transverse isotropy;

5) Determine the elastic modulus of the layered rock mass in combination with the survey results of the rock mass structure on site and the empirical formula to verify the rock mass deformation index determined earlier.

The further improvement of the technical scheme of the present invention is: the test system used in the rock mass uniaxial compression test and the pressure-bearing plate test includes three parts: the adding system, the force transmission system and the measuring system; the pressurizing system includes a high-pressure oil pump, a hydraulic pressure regulator , hydraulic jacks, electric or hand-operated oil pumps, high-pressure oil pipes and high-pressure quick connectors, and pressure gauges with a range of 10-50Mpa; the force transmission system includes a pressure bearing plate, a force transmission column and a steel backing plate; the measurement system includes a gauge Brackets, magnetic watch stands or universal watch stands and dial indicators, rock mass lateral deformation measuring lines.

The further improvement of the technical scheme of the present invention is: 2-3 hydraulic jacks, 2-3 electric or hand-operated oil pumps, 2-3 pressure gauges; 2-4 measuring gauge brackets, magnetic watch frame or universal There are 5 to 7 watch frames and 5 to 7 dial indicators; the thickness of the bearing plate is 3 cm to 4 cm, and the thickness of the steel backing plate is 2 cm to 3 cm.

The further improvement of the technical solution of the present invention is that: in step 2, the specific operation of the uniaxial compression test of the rock mass is to stack the pressure-bearing plate, the jack, the steel backing plate, the force-transmitting plate and the force-transmitting plate in sequence from bottom to top on the upper part of the processed cubic rock sample. Column and steel backing plate, the uppermost steel backing plate is anchored on the top wall of the test hole with an anchor; Place the gauge bracket of the dial indicator, the dial indicator is fixed on the gauge bracket by the magnetic gauge frame or the universal gauge frame, and four dial gauges are arranged at the four corners of the pressure-bearing plate to measure the vertical deformation of the surface of the test piece; Circumferential survey lines test the lateral deformation of the rock sample under axial compression.

A further improvement of the technical solution of the present invention is that: in step 4, the specific operation of the vertical bearing plate test is to select the test position and then stack the bearing plate, jack, steel backing plate, The force transmission column and the steel backing plate, the uppermost steel backing plate is anchored on the top wall of the test hole with the anchor rod; then the supports for placing the meter brackets are respectively set on both sides of the bearing plate and fixed on the supports A gauge bracket for placing the dial gauge. The dial gauge is fixed on the gauge bracket by a magnetic gauge frame or a universal gauge frame. Four dial gauges are arranged at the four corners of the pressure-bearing plate to measure the vertical deformation of the surface of the test piece. ; The test system is installed and debugged and tested and processed after a certain period of maintenance.

The further improvement of the technical solution of the present invention is: the specific operation of the horizontal bearing plate test in step 4 is to make a horizontal bearing platform in the test hole and select a test position, and at the test position, the horizontal direction of the test position is sequentially arranged. The bearing plate, the jack, the steel backing plate, the force transmission column and the steel backing plate in contact with the rock wall on the other side are placed in contact with the wall; For the gauge brackets at the top and bottom, two horizontal gauge brackets are welded between the two vertical gauge brackets; 4 dial gauges are arranged at the four corners of the pressure-bearing plate, and the surface of the test piece is horizontally deformed during the test; The test system is installed and debugged and tested after a certain period of maintenance.

The further improvement of the technical solution of the present invention is that: the specific steps of installing and debugging the testing system and carrying out the testing test after a certain period of maintenance are as follows:

(1), preparation work

Determine the maximum test pressure according to 1.2 times the design pressure; measure and read the initial readings of each meter, read once every 10 minutes before pressurization, and start pressurizing if the readings remain unchanged for three consecutive times;

(2), rock mass uniaxial compression test

In the pre-compression stage of the rock mass, a certain pressure is applied to the rock mass to pre-press the rock mass to close the micro-cracks in the rock mass; the test rock sample is subjected to a graded loading test, and the axial pressure-deformation curve, axial deformation- The lateral deformation curve is used to obtain the vertical elastic modulus E _y and Poisson's ratio μ _y of the horizontal layered rock mass.

(2) The first loading and unloading of the bearing plate test

Divide the determined maximum pressure into 6 levels and apply pressure in stages; the pressurization method adopts multiple small cycles of loading and unloading step by step; for the vertical loading test, except that the pressure of the last stage is unloaded to zero, all other pressures should be retained The contact pressure is 0.1MPa to ensure safe operation and avoid the tipping of the force transmission column.

(3) Repeat the loading and unloading process of the bearing plate test

After the first stage pressure is discharged, the next stage pressure is applied, and so on until the last stage pressure.

(4) Test record and observation of bearing plate

During the test, read and record while reading, and observe the deformation and failure of the specimen; draw the 6-level cyclic loading and unloading pressure-deformation curves in the vertical and horizontal bearing plate tests respectively.

The further improvement of the technical solution of the present invention is: in step 4 of the method for comprehensively determining the deformation parameters of the horizontal layered rock mass, the specific steps of determining five deformation indexes reflecting the transverse isotropy of the horizontal layered rock mass are as follows:

1), build a three-dimensional numerical model

The size of the three-dimensional numerical model is determined by 3 to 5 times the size of the test hole, and the top surface of the model is the actual ground shape of the test site; the transverse isotropic mechanics of the layered rock mass is input with the aid of the anisotropic medium-joint rock mass constitutive model in the finite element program. Indicators, including the vertical elastic modulus Ey, Poisson's ratio μy determined by uniaxial compression test, assumed horizontal elastic modulus Ex, Poisson's ratio μx and shear modulus G; according to the horizontal and vertical bearing plate The position, shape and size of the bearing plate model are established in the model, and three physical and mechanical parameters of density, elasticity model and Poisson's ratio are assigned;

2) According to the test loading scheme of the vertical bearing plate, the simulation test of the vertical bearing plate loading and unloading is carried out in the numerical model test.

3) According to the loading plan of the horizontal bearing plate test, carry out the grading loading and unloading simulation test of the horizontal bearing plate in the numerical model test.

4), record and extract the pressure and deformation data in the vertical and horizontal bearing plate numerical simulation test, and draw the pressure-deformation curve.

5) Compare with the pressure-deformation curve measured on site, modify the rock mass deformation parameters in the numerical model according to the data deviation, re-run the numerical loading test, and compare the results; repeat the numerical test until the error is less than 10%;

6) According to the rock mass isotropic parameters input in the numerical model, the deformation indexes Ex, Ey, μx, μy and G of the horizontal layered rock mass are finally determined;

The further improvement of the technical solution of the present invention is: in step 5, the RQD values and empirical formulas of the vertical and horizontal directions of the horizontal layered rock mass are measured on site, and the elastic modulus Ex and Ey values of the horizontal layered rock mass are estimated to verify the values. The elastic modulus value determined by the inverse analysis.

Owing to having adopted the above-mentioned technical scheme, the technical effects obtained by the present invention are as follows:

The method of the invention combines the rock mass uniaxial compression test, the on-site bearing plate test data and the numerical inverse analysis of the finite element calculation program, and can finally determine five deformation indexes reflecting the transverse isotropy of the horizontal layered rock mass. Among them, the rock mass uniaxial compression test mainly determines the vertical elastic modulus Ey and Poisson’s ratio μy of the layered rock mass, and the numerical inversion model is mainly used to determine the horizontal elastic modulus Ex, Poisson’s ratio μx and shear ratio of the rock mass. Modulus G. The vertical elastic modulus Ey and the horizontal elastic modulus Ex of the rock mass estimated by the RQD value statistics and empirical formulas confirm the numerical inverse analysis results.

The invention proposes a comprehensive determination method for the deformation parameters of horizontal layered rock mass based on the combination of rock mass uniaxial compression test, field rigid bearing plate test and numerical inversion, which provides basic data for layered rock mass engineering design and construction .

Description of drawings

Fig. 1 is the three-dimensional schematic diagram of vertical bearing plate test of the present invention;

Fig. 2 is the front view of the vertical bearing plate test of the present invention

Fig. 3 is the three-dimensional schematic diagram of the horizontal pressure-bearing plate test of the present invention;

Fig. 4 is the front view of the horizontal pressure-bearing plate test of the present invention;

Fig. 5 is the schematic diagram of uniaxial compression test of the present invention;

Among them, 1. Bearing plate, 2. Jack, 3. Steel backing plate, 4. Force transmission column, 5. Gauge bracket, 6. Dial indicator, 7. Test hole, 8. Horizontal bearing platform.

Detailed ways

The present invention is described in further detail below in conjunction with the accompanying drawings and specific embodiments:

The invention discloses a method for comprehensively determining deformation parameters of a horizontally layered rock mass. The method obtains test data by carrying out a uniaxial compression test, a vertical pressure-bearing plate test and a horizontal pressure-bearing plate test in an on-site test hole, and at the same time The numerical inverse analysis was carried out by using the finite element calculation program, and the five deformation indexes reflecting the transverse isotropy of the horizontal layered rock mass were comprehensively determined based on the field test results. The method can accurately measure the deformation parameters of horizontally layered rock mass.

A method for comprehensively determining the deformation parameters of a horizontally layered rock mass, the method is carried out in a test hole on a construction site, and the test systems used in the uniaxial compression test and the bearing plate test include a pressure system, a force transmission system and a measurement system 3 parts; the pressurization system includes high-pressure oil pump, hydraulic pressure regulator, hydraulic jack, electric or hand-operated oil pump, high-pressure oil pipe and several high-pressure quick connectors and pressure gauges with a range of 10-50MPa; the force transmission system includes a pressure-bearing plate , force transmission column and steel backing plate; the measurement system includes meter bracket, magnetic meter rack or universal meter rack, dial indicator, and rock mass lateral deformation measurement line. Among them, there are 2 to 3 hydraulic jacks, 2 to 3 electric or hand-operated oil pumps, 2 to 3 pressure gauges, 2 to 4 gauge brackets, and 5 to 7 magnetic or universal gauge frames. There are 5 to 7 dial indicators; the thickness of the bearing plate is 3cm to 4cm, and the thickness of the steel backing plate is 2cm to 3cm. Include the following steps,

1) Prepare the test components, select the test position in the test hole, and prepare for the field test;

2) Carry out the uniaxial compression test of the layered rock samples in the test cave, record the axial pressure-deformation curve, the axial deformation-lateral deformation curve, and determine the vertical elastic modulus and Poisson of the horizontal layered rock mass. Compare.

The specific operation of the rock mass uniaxial compression test in this step is to stack the pressure-bearing plate, the jack, the steel backing plate, the force-transmitting column and the steel backing plate on the upper part of the processed cubic rock sample from bottom to top. The steel backing plate is anchored on the top wall of the test hole with anchor rods; then the supports for placing the gauge brackets are respectively set on both sides of the bearing plate, and the gauge brackets for placing the dial gauge are fixed on the supports. The dial gauge is fixed on the test gauge support through a magnetic gauge frame or a universal gauge frame, and four dial gauges are arranged at the four corners of the pressure-bearing plate to measure the vertical deformation of the surface of the specimen; Deforms laterally under compression.

The specific steps to carry out the test after the test system is installed and debugged and maintained for a certain period of time are as follows:

(1), preparation work

Determine the maximum test pressure according to 1.2 times of the design pressure; measure the initial reading of each meter, read once every 10 minutes before pressurization, and start to pressurize if the readings remain unchanged for three consecutive times; prepress, before the formal loading, first The rock mass is preloaded in advance;

(2), first loading and unloading

Divide the determined maximum pressure into 6 grades and apply pressure in stages; the pressurization method adopts multiple small cycles of loading and unloading step by step; read once immediately after the pressurization, and then record the load value and the corresponding load value during the loading and unloading process every 10min as needed. The vertical and lateral deformation values are determined until the deformation is stable and the pressure is relieved; when the difference between the two adjacent readings of the gauges on all the pressure-bearing plates, △Wi, and the first reading under the same pressure and the reading under the previous pressure When the ratio of the difference Wi is less than 5%, it is considered to be stable; the reading requirements during the pressure relief process are the same as those for pressurization; for the vertical loading test, except the last stage pressure is discharged to zero, the other stages of pressure should retain the contact pressure 0.1MPa to ensure safe operation and prevent the power transmission column from tipping over.

(3) Repeat the loading and unloading process

After the first stage pressure is discharged, the next stage pressure is applied, and so on until the last stage pressure.

(4), record and observe

During the test, read and record while reading, and observe the deformation and failure of the specimen; draw the vertical pressure-deformation curve and the axial deformation-lateral deformation curve respectively.

3), in the test hole vertical bearing plate test and horizontal bearing plate test and record the data and draw the pressure-deformation curve;

The specific operation of the vertical pressure-bearing plate test in this step is to select the test position and then stack the pressure-bearing plate, the jack, the steel backing plate, the force-transmitting column and the steel backing plate at the test position from bottom to top. The upper steel backing plate is anchored to the top wall of the test hole with anchor rods; then the supports for placing the gauge brackets are respectively set on both sides of the bearing plate, and the gauges for placing the dial gauge are fixed on the supports. The bracket, the dial indicator is fixed on the test bracket by the magnetic table frame or the universal indicator frame, and four dial indicators are arranged at the four corners of the pressure plate to measure the vertical deformation of the surface of the test piece; the test system is installed and debugged after a certain period of time. After the maintenance, test experiments and data processing are carried out.

The specific operation of the horizontal bearing plate test in this step is to make a horizontal bearing platform in the test hole and select the test position, and at the test position, the bearing plates and jacks that are in contact with the rock wall of the test position are sequentially arranged in the horizontal direction. , a steel backing plate, a force transmission column and a steel backing plate in contact with the rock wall on the other side; Weld 2 horizontal gauge supports between the two vertical gauge supports; 4 dial gauges are arranged at the four corners of the bearing plate, and the surface of the test piece is horizontally deformed during the test; the test system is installed and debugged after a certain period of time. After curing, carry out the test test.

The specific steps to carry out the test after the test system is installed and debugged and maintained for a certain period of time are as follows:

(1), preparation work

Determine the maximum test pressure according to 1.2 times the design pressure; measure and read the initial readings of each meter, read once every 10 minutes before pressurization, and start pressurizing if the readings remain unchanged for three consecutive times;

(2), first loading and unloading

Divide the determined maximum pressure into 6 grades and apply pressure in stages; the pressurization method adopts multiple small cycles of loading and unloading step by step; read once immediately after the pressurization, and then record the load value and the corresponding load value during the loading and unloading process every 10min as needed. Deformation value until the deformation is stable and then unloaded; when the ratio of the difference between the two adjacent readings of the gauges on all the pressure-bearing plates, △Wi, and the difference between the first reading under the same pressure and the reading under the previous pressure, is less than 5%, it is considered to be stable; the reading requirements during the pressure relief process are the same as those for pressurization; for the vertical loading test, except the last stage pressure is released to zero, the other stages of pressure should retain the contact pressure of 0.1MPa to ensure Safe operation, avoid the power transmission column toppling.

(3) Repeat the loading and unloading process

After the first stage pressure is discharged, the next stage pressure is applied, and so on until the last stage pressure.

(4), record and observe

During the test, read and record while reading, and observe the deformation and failure of the specimen; draw the 6-level cyclic loading and unloading pressure-deformation curves in the vertical and horizontal bearing plate tests respectively.

4) Use the finite element calculation program to carry out numerical inverse analysis, and comprehensively determine the five deformation indicators reflecting the transverse isotropy of the horizontal layered rock mass based on the field test results.

The specific sub-steps in the operation of this step are:

1), build a three-dimensional numerical model

The size of the three-dimensional numerical model is determined by 3 to 5 times the size of the test hole, and the top surface of the model is the actual surface shape of the test site; the transverse isotropic deformation of the layered rock mass is input by means of the anisotropic medium-joint rock mass constitutive model in the finite element program Indicators, including the vertical elastic modulus Ey, Poisson’s ratio μy measured according to uniaxial compression test, assumed horizontal elastic modulus Ex, Poisson’s ratio μx and shear modulus G; according to the horizontal and vertical bearing plate The position, shape and size of the bearing plate model are established in the model, and three physical and mechanical parameters of density, elasticity model and Poisson's ratio are assigned;

2) According to the test loading scheme of the vertical bearing plate, the simulation test of the vertical bearing plate loading and unloading is carried out in the numerical model test.

3) Strictly follow the loading plan of the horizontal bearing plate test, and carry out the hierarchical loading and unloading simulation test of the horizontal bearing plate in the numerical model test.

4), record and extract the pressure and deformation data in the vertical and horizontal bearing plate numerical simulation test, and draw the pressure-deformation curve.

5) Compare with the pressure-deformation curve measured on site, modify the rock mass deformation parameters in the numerical model according to the data deviation, re-run the numerical loading test, and compare the results; repeat the numerical test until the error is less than 10%;

6) Integrate field tests and data processing, and finally determine the deformation parameters Ex, Ey, μx, μy and G of the horizontal layered rock mass.

5) Determine the elastic modulus of the layered rock mass in combination with the survey results of the rock mass structure on site and the empirical formula to verify the rock mass deformation index determined earlier.

In this step, according to the vertical and horizontal RQD values and empirical formulas of the horizontal layered rock mass measured on site, the elastic modulus Ex and Ey values of the horizontal layered rock mass are estimated, and the elastic modulus value determined by the numerical inverse analysis is confirmed.

The method of the invention combines the field test data and the numerical inverse analysis of the finite element calculation program, and can finally determine five deformation indexes reflecting the transverse isotropy of the horizontal layered rock mass. Among them, the rock mass uniaxial compression test mainly determines the vertical elastic modulus Ey and Poisson’s ratio μy of the layered rock mass, and the numerical inversion model is mainly used to determine the horizontal elastic modulus Ex, Poisson’s ratio μx and shear ratio of the rock mass. Modulus G. The rock mass RQD value statistics and empirical formulas are used to estimate the rock mass's normal elastic modulus Ey and horizontal elastic modulus Ex, which confirms the results of numerical inverse analysis.

The following are specific examples:

First, select a special test hole on the site. The test hole is about 2m high and about 3.5m wide. Based on the principle of convenient test operation, the rock mass test hole with good integrity can be excavated into a flat-topped rectangular section, and the rock mass with poor integrity can be excavated. The body test hole can be excavated into a straight wall arch. The components used in preparing the test, the test system used in the pressure-bearing plate test includes three parts: the pressure system, the force transmission system and the measurement system; the pressure system includes a high-pressure oil pump, a hydraulic pressure regulator, and a hydraulic jack 3 sets, 3 sets of electric or hand-operated oil pumps, several high-pressure oil pipes and high-pressure quick connectors, and 3 pressure gauges with a range of 10 to 50Mpa; the force transmission system includes a pressure bearing plate with a thickness of 3cm to 4cm, a force transmission column and a thickness of It is a steel backing plate of 2cm to 3cm; the measuring system includes 4 measuring watch brackets, 7 magnetic watch frames or universal watch frames and 7 dial indicators. Among them, the steel backing plate and the bearing plate are made of steel plate, and the meter bracket can be made of steel pipe or I-beam.

After the preparations are made, a specific test is carried out, including the following steps,

1), prepare the test components, select the test position in the test hole 7, and prepare for the field test. Usually, the middle part of the ground of the test hole 7 is selected as the test position of the vertical bearing plate 1 test.

2) Carry out the uniaxial compression test of the layered rock samples in the test cave, record the axial pressure-deformation curve, the axial deformation-lateral deformation curve, and determine the vertical elastic modulus and Poisson of the horizontal layered rock mass. Compare.

The specific operation of the uniaxial compression test of the rock mass in this step is to stack the pressure bearing plate 1, the jack 2, the steel backing plate 3, the force transmission column 4 and the steel backing plate on the upper part of the processed cubic rock sample from bottom to top. 3. The uppermost steel backing plate 3 is anchored to the top wall of the test hole 7 with an anchor rod; then two sides of the bearing plate 1 are respectively provided with supports for placing the meter brackets and fixedly set on the supports for placing The gauge stand 5 of the dial gauge 6, the dial gauge 6 is fixed on the gauge stand 5 by a magnetic gauge stand or a universal gauge stand, and four dial gauges are arranged at the four corners of the pressure-bearing plate 1 to measure the vertical dimension of the rock sample surface. The lateral deformation of the rock sample under axial compression is tested by using the circumferential survey line. Specifically as shown in Figure 5.

The specific steps to carry out the test after the test system is installed and debugged and maintained for a certain period of time are as follows:

(1), preparation work

Determine the maximum test pressure according to 1.2 times of the design pressure; measure the initial reading of each meter, read once every 10 minutes before pressurization, and start to pressurize if the readings remain unchanged for three consecutive times; prepress, before the formal loading, first The rock mass is preloaded in advance;

(2), first loading and unloading

Divide the determined maximum pressure into 6 grades and apply pressure in stages; the pressurization method adopts multiple small cycles of loading and unloading step by step; read once immediately after the pressurization, and then record the load value and the corresponding load value during the loading and unloading process every 10min as needed. The vertical and lateral deformation values are determined until the deformation is stable and the pressure is relieved; when the difference between the two adjacent readings of the gauges on all the pressure-bearing plates, △Wi, and the first reading under the same pressure and the reading under the previous pressure When the ratio of the difference Wi is less than 5%, it is considered to be stable; the reading requirements during the pressure relief process are the same as those for pressurization; for the vertical loading test, except the last stage pressure is discharged to zero, the other stages of pressure should retain the contact pressure 0.1MPa to ensure safe operation and prevent the power transmission column from tipping over.

(3) Repeat the loading and unloading process

After the first stage pressure is discharged, the next stage pressure is applied, and so on until the last stage pressure.

(4), record and observe

During the test, read and record while reading, and observe the deformation and failure of the specimen; draw the axial pressure-deformation curve and the axial deformation-lateral deformation curve respectively. Among them, the lateral deformation can take the average value of the test results of the three measuring lines

When loading and unloading, it is necessary to strictly follow the test specifications.

3) In the test hole, test the vertical bearing plate 1 and the horizontal bearing plate 1 and record the data and draw the pressure deformation curve.

The specific operation of the vertical bearing plate 1 test in this step is to smooth the surface of the test position with cement mortar mixed with a quick-setting agent, and then stack the bearing plate 1 and the jack 2 at the test position from bottom to top. , steel backing plate 3, force transmission column 4 and steel backing plate 3, the uppermost steel backing plate 3 is anchored on the top wall of the test hole 7 with an anchor rod. During installation, attention should be paid to keep all components of the entire test system on the same axis and consistent with the direction of compression and the normal direction of the horizontal layered rock mass; the steel plate between the force transmission column 4 and the surrounding rock at the top of the cave can be anchored by bolts On the surface of the surrounding rock, depending on the flatness of the surrounding rock, the surface of the surrounding rock at the anchoring position can be smoothed with mortar before the steel backing plate 3 is anchored. Then it is the layout of the measuring system. Five measuring gauges are placed between the two sides of the bearing plate 1, which is supported by a simply supported beam. The fulcrum of the fixed bracket must be placed outside the range of influence of the test; Four dial indicators 6 are arranged at the four corners, and the surface of the test piece is vertically deformed during the test. Specifically, the two sides of the pressure-bearing plate 1 are respectively provided with supports for placing the gauges 5, and the gauges 5 for placing the dial gauge 6 are fixedly arranged on the supports, and the dial gauge 6 passes through. The magnetic meter stand or universal meter stand is fixed between the test meters 5, and four dial indicators 6 are arranged at the four corners of the pressure plate 1 to measure the vertical deformation of the surface of the test piece; the test system is installed and debugged and maintained for a certain period of time. After the test experiment and data processing. Specifically, as shown in Figure 1 and Figure 2.

The specific operation of the test of the horizontal bearing plate 1 in this step is to first make a horizontal bearing platform with a height of about 1.5m, a width of 50cm and a length of the width of the test hole 7 in the test hole 7, and select the side wall of the test hole 7 as the test position . If the side wall of the test hole 7 is not flat, use the cement mortar mixed with the accelerator to smooth the test surface of the rock mass, and then place the bearing plate 1 vertically and tap it to make it closely combined. At the test position, the bearing plate 1, the jack 2, the steel backing plate 3, the force transmission column 4 and the steel backing plate 3 in contact with the rock wall on the other side are sequentially arranged in the horizontal direction at the test position. Then, on both sides of the bearing plate 1, the two ends are vertically placed between the measuring gauges 5 at the top and bottom of the test hole 7, respectively, and two horizontal measuring gauges are welded between the two vertical measuring gauges 5. 5 between the tables; 4 dial indicators 6 are arranged at the four corners of the pressure-bearing plate 1, and the surface of the specimen is horizontally deformed during the test and test; the test system is installed and debugged and tested after a certain period of maintenance. During installation, attention should be paid to keeping all components of the entire test system on the same axis and consistent with the direction of compression and the direction of the horizontal layered rock mass. The position where the concrete is used needs to be cured for a period of time before the test can be carried out. Specifically, as shown in Figure 3 and Figure 4.

The specific steps to carry out the test after the test system is installed and debugged and maintained for a certain period of time are as follows:

(1), preparation work

Determine the maximum test pressure according to 1.2 times the design pressure; measure and read the initial readings of each meter, read once every 10 minutes before pressurization, and start pressurizing if the readings remain unchanged for three consecutive times;

(2), first loading and unloading

Divide the determined maximum pressure into 6 grades and apply pressure in stages; the pressurization method adopts multiple small cycles of loading and unloading step by step; read once immediately after the pressurization, and then record the load value and the corresponding load value during the loading and unloading process every 10min as needed. Deformation value until the deformation is stable and then unloaded; when the difference between the two adjacent readings of the measuring gauges on all the pressure plates 1, △Wi and the difference between the first reading under the same pressure and the reading under the previous pressure Wi ratio When it is less than 5%, it is considered to be stable; the reading requirements during the pressure relief process are the same as those for pressurization; for the vertical loading test, except the last stage pressure is released to zero, the other stages of pressure should retain the contact pressure of 0.1MPa, with a minimum of 0.1MPa. To ensure safe operation, to prevent the power transmission column 4 from tipping over.

(3) Repeat the loading and unloading process

After the first stage pressure is discharged, the next stage pressure is applied, and so on until the last stage pressure.

(4), record and observe

During the test, read and record while reading, and observe the deformation and damage of the specimen, and correct and deal with it in time if any problem is found. After the test, according to the recorded data, the 6-level cyclic loading and unloading pressure-deformation curves in the vertical and horizontal bearing plate 1 test were drawn respectively.

When loading and unloading, it is necessary to strictly follow the test specifications.

4) Use the finite element calculation program to carry out numerical inverse analysis, and comprehensively determine the five deformation indicators reflecting the transverse isotropy of the horizontal layered rock mass based on the field test results.

The specific sub-steps in the operation of this step are:

1), build a three-dimensional numerical model

The size of the three-dimensional numerical model is determined by 3 to 5 times the size of the test hole 7, and the top surface of the model is the actual ground shape of the test site; the transverse isotropy of the layered rock mass is input by means of the anisotropic medium-joint rock mass constitutive model in the finite element program Mechanical indicators, including the vertical elastic modulus Ey, Poisson’s ratio μy measured according to uniaxial compression test, assumed horizontal elastic modulus Ex, Poisson’s ratio μx and shear modulus G; The plate position, shape and size are established in the model to establish the bearing plate model, and three physical and mechanical parameters are assigned to the density, elastic model and Poisson's ratio;

2) According to the test loading scheme of the vertical bearing plate 1, the simulation test of the hierarchical loading and unloading of the vertical bearing plate 1 is carried out in the numerical model test.

3) Strictly follow the test loading plan of the horizontal bearing plate 1, and carry out the hierarchical loading and unloading simulation test of the horizontal bearing plate 1 in the numerical model test.

4), record and extract the pressure and deformation data in the numerical simulation test of the vertical and horizontal bearing plate 1, and draw the pressure-deformation curve diagram.

5) Compared with the pressure-deformation curve measured on site, modify the rock mass deformation parameters in the numerical model according to the data deviation, re-run the numerical loading test, and compare the results; repeat the numerical test until the error is less than 10%;

6) Based on the field test and numerical inversion results, the rock mass deformation parameters used in the numerical simulation are the deformation parameters Ex, Ey, μx, μy and G of the horizontal layered rock mass.

7) Estimate the elastic modulus Ex and Ey values of the horizontal layered rock mass according to the vertical and horizontal RQD values and empirical formulas of the horizontal layered rock mass measured on site, and verify the elastic modulus value of the rock mass determined by the numerical inverse analysis. .

In this embodiment, the deformation parameters Ex, Ey, μx, μy and G of the horizontal layered rock mass can be finally determined, which provides basic data for the engineering design and construction of the layered rock mass.

Claims (3)

1. a comprehensive method for determining the deformation parameters of a horizontal layered rock mass, is characterized in that: the method is carried out in the test hole of the construction site, comprising the following steps, 1) Prepare the test components, select the test position in the test hole, and prepare for the field test; 2) Carry out the uniaxial compression test of the layered rock samples in the test cave, record the axial pressure-deformation curve, the axial deformation-lateral deformation curve, and determine the vertical elastic modulus and Poisson of the horizontal layered rock mass. ratio; the test system used in the rock mass uniaxial compression test and the pressure bearing plate test includes three parts: pressure system, force transmission system and measurement system; the pressure system includes high pressure oil pump, hydraulic pressure stabilizer, hydraulic jack, electric or Hand-operated oil pump, high-pressure oil pipe and several high-pressure quick connectors, and pressure gauges with a range of 10 to 50Mpa; the force transmission system includes a pressure plate, a force transmission column and a steel backing plate; the measurement system includes a gauge stand, a magnetic gauge stand or Universal meter frame, dial indicator, and rock mass lateral deformation measurement line; the specific operation of the rock mass uniaxial compression test is to stack the bearing plate, jack, and steel pad from bottom to top on the upper part of the processed cube rock sample. Plate, force transmission column and steel backing plate, the uppermost steel backing plate is anchored on the top wall of the test hole with an anchor; A meter bracket for placing the dial indicator is fixed, and the dial indicator is fixed on the meter bracket by a magnetic meter bracket or a universal meter bracket, and four dial indicators are arranged at the four corners of the pressure-bearing plate to measure the vertical dimension of the surface of the test piece. The lateral deformation of the rock sample under axial compression is tested by using the circumferential measurement line; 3) Carry out the vertical bearing plate test and the horizontal bearing plate test in the test hole and record the data and draw the pressure-deformation curve; The specific steps of the test system installation and debugging and the test test after a certain period of maintenance are as follows: (1), preparation work Determine the maximum test pressure according to 1.2 times the design pressure; measure and read the initial readings of each meter, read once every 10 minutes before pressurization, and start pressurizing if the readings remain unchanged for three consecutive times; (2), rock mass uniaxial compression test In the pre-compression stage of the rock mass, a certain pressure is applied to the rock mass to pre-press the rock mass to close the micro-cracks in the rock mass; the test rock sample is subjected to a graded loading test, and the axial pressure-deformation curve, axial deformation- The lateral deformation curve is used to obtain the vertical elastic modulus Ey and Poisson’s ratio μy of the horizontal layered rock mass; (3) The first loading and unloading of the bearing plate test Divide the determined maximum pressure into 6 levels and apply pressure in stages; the pressurization method adopts multiple small cycles of loading and unloading step by step; for the vertical loading test, except that the pressure of the last stage is unloaded to zero, all other pressures should be retained The contact pressure is 0.1MPa to ensure safe operation and avoid the tipping of the force transmission column; (4) Repeat the loading and unloading process of the bearing plate test After the first-stage pressure is discharged, the next-stage pressure is applied, and this is repeated until the last-stage pressure, and the reading requirements under the pressure of each stage are the same; (5) Test record and observation of bearing plate During the test, read and record while reading, and observe the deformation and failure of the specimen; draw the 6-level cyclic loading and unloading pressure-deformation curves in the vertical and horizontal bearing plate tests respectively; 4) According to the uniaxial test results of the layered rock mass and the pressure-deformation curve of the vertical bearing plate test and the horizontal bearing plate test, use the finite element calculation program to carry out numerical inverse analysis, and finally comprehensively determine the reaction of the horizontal layered rock mass Five deformation indexes of transverse isotropy; the specific operation of the vertical bearing plate test is to select the test position, smooth the surface of the test part with cement mortar, and then stack the bearing plates at the test position from bottom to top. The pressure plate, jack, steel backing plate, force transmission column and steel backing plate, the uppermost steel backing plate is anchored on the top wall of the test hole with anchor rods; The support is fixed on the support, and a gauge bracket for placing the dial indicator is fixed on the support. It is used to measure the vertical deformation of the surface of the specimen; the test system is installed and debugged and tested and processed after a certain period of maintenance; The specific operation of the horizontal bearing plate test is to make a horizontal bearing platform in the test hole and select the test position, smooth the surface of the test part with cement mortar, and set up the horizontal direction at the test position in order to contact the rock wall of the test position. The bearing plate, the jack, the steel backing plate, the force transmission column and the steel backing plate in contact with the rock wall on the other side; Test meter bracket, weld 2 horizontal meter brackets between two vertical meter brackets; 4 dial indicators are arranged at the four corners of the pressure-bearing plate, and the surface of the test piece is horizontally deformed during the test; the test system is installed and debugged And after a certain period of maintenance, test and test; In this step, the specific steps for determining the five deformation indexes reflecting the transverse isotropy of the horizontal layered rock mass are as follows: (1), establish a three-dimensional numerical model The size of the three-dimensional numerical model is determined by 3 to 5 times the size of the test hole, and the top surface of the model is the actual surface form of the test site; the transverse isotropic mechanics of the layered rock mass is input by means of the anisotropic medium-joint rock mass constitutive model in the finite element program Indicators, including the vertical elastic modulus Ey, Poisson’s ratio μy measured according to uniaxial compression test, assumed horizontal elastic modulus Ex, Poisson’s ratio μx and shear modulus G; according to the horizontal and vertical bearing plate The position, shape and size of the bearing plate model are established in the model, and three physical and mechanical parameters of density, elasticity model and Poisson's ratio are assigned; (2) According to the test loading plan of the vertical bearing plate, the simulation test of the vertical bearing plate loading and unloading is carried out in the numerical model test; (3) According to the loading plan of the horizontal bearing plate test, the simulation test of the hierarchical loading and unloading of the horizontal bearing plate is carried out in the numerical model test; (4) Record and extract the pressure and deformation data in the vertical and horizontal bearing plate numerical simulation test, and draw the pressure-deformation curve; (5) Compared with the pressure-deformation curve measured by the on-site bearing plate test, modify the deformation parameters of the rock mass in the numerical model according to the data deviation, re-run the numerical loading test, and compare the results; repeat the numerical test until the error is less than 10%; (6) According to the isotropic deformation parameters of the rock mass input in the numerical model, the deformation indexes Ex, Ey, μx, μy and G of the horizontal layered rock mass are finally determined; 5) Determine the elastic modulus of the horizontal layered rock mass in combination with the investigation results of the rock mass structure on site and the empirical formula, so as to confirm the rock mass deformation index determined earlier. 2. The method for comprehensively determining the deformation parameters of a horizontally layered rock mass according to claim 1, wherein the number of hydraulic jacks is 2 to 3, the number of electric or hand-operated oil pumps is 2 to 3, and the pressure gauge is 2 ～3 pieces; 2～4 pieces of measuring watch brackets, 5～7 pieces of magnetic watch stand or universal watch stand, 5～7 pieces of dial indicator; the thickness of the bearing plate is 3cm～4cm, and the thickness of the steel backing plate is 2cm～ 3cm. 3. a kind of horizontal layered rock mass deformation parameter comprehensive determination method according to claim 1, is characterized in that: in step 5, be according to the RQD value and empirical formula of vertical and horizontal direction of horizontal layered rock mass measured on site, The elastic modulus Ex and Ey values of the horizontal layered rock mass are estimated, and the elastic modulus value determined by the numerical inverse analysis is confirmed.

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