CN103076245A - Method for measuring change law and values of deep-buried hard rock mechanical parameters - Google Patents

Abstract

The invention solves technical problems by providing a method for measuring the change law and the values of deep-buried hard rock mechanical parameters. The method is fulfilled by adopting an axial stress overall-process circulatory loading and unloading experiment in the existence of confining pressure, is mainly used for solving the technical problem of measuring the change law and the values of the mechanical parameters of rock in the surrounding rock damaged zone in underground chambers with deep-buried hard rock, can effectively acquire the change law of the mechanical parameters of rock in the excavation damaged zone, and measures the value of rock mechanical parameters at different variation stages.

Description

The assay method of a kind of buried hard rock mechanics parameter Changing Pattern and value

Technical field

The present invention relates to buried hard rock mechanics study technical field, refer to particularly the assay method of a kind of buried hard rock mechanics parameter Changing Pattern and value.

Technical background

Buried hard rock underground chamber adds in the uninstall process at excavation, easily forms excavation damage zone (excavation damaged zone is called for short EDZ) in country rock certain depth scope.The formation of this EDZ of cavern is that the acting in conjunction of the strong release of Blasting Excavation vibrations and coupling terrestrial stress causes.In the rock mass of EDZ inside, the original joint crack is progressively expanded, and new crack constantly produces, and causes rock mass mechanics behavior generation significant change, and the inner bearing capacity of the wall rock of simultaneous EDZ reduces with the increase of Rock Damage.In this course, the rock mechanics parameters of EDZ inside such as deformation parameter and strength parameter be corresponding changing also, how to measure and assess this change procedure and the rule of rock mechanics parameters, and obtain the technical barrier that corresponding mechanics parameter value is present not yet effective solution.In addition, the Changing Pattern of rock mechanics parameters and value are significant to the appraisal of buried hard rock underground rock cavern stability, can assist and carry out the deep-buried underground engineering optimal design.

In fact, hard rock because the generation of opening, expand, gathering nuclear or new crack of rock interior crackle etc. can form certain irrecoverable distortion, has namely produced plastic yield in adding the unloading test process.Be accompanied by the generation of plastic yield, damage of rock increases gradually, and the mechanics parameter of rock progressively changes.This process can add unloading test by the rock circulation and measure.Add the distortion that forms in the uninstall process at rock and be divided into recoverable elastic deformation and expendable plastic yield, elastic deformation wherein can be recovered after unloading is finished, and plastic yield is because irrecoverable, adds progressively accumulation in the uninstall process in repeatedly circulation.This accumulation of plastic yield can add by circulating at a rock sample unloading test and record.But how utilizing circulation to add Changing Pattern and the value that unloading test obtains buried hard rock underground rock cavern damage zone rock mechanics parameters, is the key technical problem of being badly in need of solution.

Summary of the invention

Purpose of the present invention is exactly the assay method that a kind of buried hard rock mechanics parameter Changing Pattern and value will be provided, the method utilization circulation adds Changing Pattern and the value that unloading test obtains buried hard rock underground rock cavern damage zone rock mechanics parameters, provides technical support for improving yield of deep-buried cavities stability and optimization of support design.

For realizing this purpose, the buried hard rock mechanics parameter Changing Pattern that the present invention is designed and the assay method of value, it comprises the steps:

Step 1: drill through at the scene buried hard rock core, and the hard rock core is processed into cylindrical rock sample;

Step 2: above-mentioned cylindrical rock sample is carried out three axles loading test, and set the confined pressure predetermined value in the three axles loading test, thereby obtain the peak strength of cylindrical rock sample when different confined pressure predetermined value;

Step 301, the cylindrical rock sample that step 1 is obtained is installed on the servocontrol rock implosion test machine, at this cylindrical rock sample shaft position sensor and hoop displacement transducer is installed, and can be guaranteed real-time transmission data;

Step 302, control servocontrol rock implosion test machine, cylindrical rock sample is carried out the circulation of axial stress overall process add the unloading test, in the test before arriving the rock sample peak strength, the load phase of servocontrol rock implosion test machine is pressed displacement control mode control, and unloading phase adopts axial stress control, when the axial stress of cylindrical rock sample more than or equal to cylindrical rock sample peak strength 80 ~ 90% the time, unloading phase adopts displacement control, and load phase also adopts displacement control;

Step 303, set cycle index and mode that above-mentioned axial stress overall process circulation adds the unloading test, wherein to add the cycle index of unloading test be 15 ~ 20 times for axial stress overall process circulation, during each unloading, axially deviatoric stress is offloaded to 0.1MPa, then begin to load, guarantee continuity and the integrality of process of the test;

Step 304, apply confined pressure to a certain predetermined value, keep confined pressure constant, cylindrical rock sample is carried out the circulation of axial stress overall process add the unloading test, wherein in 30% of cylindrical rock sample peak previous peaks intensity, 40%, 50%, 60% and 70% respectively once circulates adds unloading, 80% of peak strength, 85%, 90%, 95% and 100% respectively once circulates adds unloading, descending branch is carried out 4 ~ 6 circulations and is added unloading behind the peak of cylindrical rock sample peak value, the residual strength section is carried out 3 ~ 4 circulations and is added unloading behind the peak of cylindrical rock sample peak value, records confined pressure, each adds unloading circulation maximum axial stress, axial displacement and lateral shift parameter;

Step 401 is according to elastic modulus

, Poisson ratio , bulk modulus

, modulus of shearing

Calculate above-mentioned each circulation and add unloading rock deformation parameter value, wherein, Δ σ ₁, Δ ε ₁, Δ ε ₃Represent respectively axial stress increment, axial strain increment and the lateral strain increment of one section of the 5 ~ 10MPa of whenever being separated by in the loading section that above-mentioned each circulation adds unloading; Δ σ _m, Δ ε _m, Δ τ ₈, Δ γ ₈Represent respectively mean normal stress increment, average normal strain increment, octahedral shear stress increment and the octohedral shear strain increment of one section of the 5 ~ 10MPa of whenever being separated by in the loading section that above-mentioned each circulation adds unloading; Add the axial plastic strain ε that obtains cylindrical rock sample the unloading test from above-mentioned axial stress overall process circulation ₁ ^pWith side direction plastic strain ε ₃ ^p, then according to generalized plasticity strain formula Calculate each the circulation and add the generalized plasticity strain of unloading; Add the elastic modulus that unloading obtains with circulate at every turn

, Poisson ratio

, bulk modulus

And modulus of shearing

Parameter is depicted as respectively curve map with corresponding generalized plasticity strain, obtains the Changing Pattern of these deformation parameters and generalized plasticity strain by above-mentioned curve map, and can obtain the value of corresponding elastic modulus, Poisson ratio, bulk modulus and modulus of shearing;

Step 402, each corresponding with the generalized plasticity strain facies under the different confined pressures added unloading circulation maximum axial stress be depicted as curve map, adopt interpolation method obtain under the different confined pressures identical generalized plasticity strain corresponding each add unloading circulation maximum axial stress, and adopt mole-enclosed pasture yield criteria, return and obtain cohesive strength c corresponding to this generalized plasticity strain and angle of internal friction

Value increases the generalized plasticity strain value, analogizes one by one, can obtain many group corresponding cohesive strength c of different generalized plasticity strains and angle of internal friction

Value is with cohesive strength c and angle of internal friction

Value is depicted as respectively curve map with corresponding generalized plasticity strain, by this curve description cohesive strength c and angle of internal friction

With the Changing Pattern of generalized plasticity strain, and obtain corresponding cohesive strength c and angle of internal friction Value.

In the described step 302, before arriving the rock sample peak strength, the load phase of servocontrol rock implosion test machine is pressed displacement control mode control in the test, and the rate of displacement of its loading is 0.001mm/s, unloading phase adopts axial stress control, and the unloading rate of stressing is 0.1MPa/s; When the axial stress of cylindrical rock sample more than or equal to cylindrical rock sample peak strength 80 ~ 90% the time, unloading phase adopts displacement control, rate of debarkation is 0.01mm/s, load phase also adopts displacement control, loading speed is 0.01mm/s.

In the described step 304, the predetermined range that applies confined pressure is 5MPa ~ 40MPa.

In the described step 1, the buried hard rock core that drills through is processed into diameter and aspect ratio is the cylindrical rock sample of 1:2.

The diameter of described cylindrical rock sample is 50 mm, highly for 100mm.

Described step 2 comprises the steps:

Step 2.1, carrying out before axial stress overall process circulation adds unloading test, engineering zone terrestrial stress value according to actual measurement or inverting acquisition, design at least 4 kinds of confined pressure predetermined values, every kind of required rock sample of confined pressure is 3 ~ 5, is convenient to utilize mole-enclosed pasture yield criteria to obtain cohesive strength and the angle of internal friction equal strength parameter of rock;

Step 2.2, according to the confined pressure of setting, carry out the normal triaxial load test of cylindrical rock sample under the different confined pressures, the peak strength of the cylindrical rock sample that obtains when different confined pressure predetermined value is so that definite axial stress overall process circulation adds the axial stress value when unloading beginning when unloading test at every turn.

A kind of buried hard rock mechanics parameter Changing Pattern that the present invention proposes and the assay method of value, can accurately and reliably obtain buried hard rock mechanics parameter Changing Pattern and value, effectively solve the Changing Pattern of buried hard rock underground rock cavern damage zone rock mechanics parameters and the determination techniques problem of value, the buried hard rock mechanics parameter Changing Pattern and the corresponding value that obtain are applied to buried hard rock underground rock cavern estimation of stability, can significantly improve reliability and the accuracy of deep-buried underground engineering optimal design, reduce construction costs.

Description of drawings

Fig. 1 is that the circulation of marble 40MPa confined pressure adds the axial deviatoric stress of unloading and strain stress relation figure;

Fig. 2 marble elastic modulus-generalized plasticity strain curve figure;

Fig. 3 marble Poisson ratio-generalized plasticity strain curve figure;

Fig. 4 marble axial stress-generalized plasticity strain curve figure;

Fig. 5 marble angle of internal friction-generalized plasticity strain curve figure;

Fig. 6 marble cohesive strength-generalized plasticity strain curve figure.

Ordinate is axial deviatoric stress among Fig. 1, horizontal ordinate is strain, and ordinate is elastic modulus among Fig. 2, and horizontal ordinate is the generalized plasticity strain, ordinate is Poisson ratio among Fig. 3, horizontal ordinate is the generalized plasticity strain, and ordinate is axial stress among Fig. 4, and horizontal ordinate is the generalized plasticity strain, ordinate is angle of internal friction among Fig. 5, horizontal ordinate is the generalized plasticity strain, and ordinate is cohesive strength among Fig. 6, and horizontal ordinate is the generalized plasticity strain.

Embodiment

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

The assay method of a kind of buried hard rock mechanics parameter Changing Pattern and value is characterized in that it comprises the steps:

Step 1: drill through at the scene buried hard rock core, and the hard rock core is processed into cylindrical rock sample;

Step 2: above-mentioned cylindrical rock sample is carried out conventional three axles loading test, and set the confined pressure predetermined value in the three axles loading test, thereby obtain the peak strength of cylindrical rock sample when different confined pressure predetermined value;

Step 301, the cylindrical rock sample that step 1 is obtained is installed on the existing servocontrol rock implosion test machine, at this cylindrical rock sample shaft position sensor and hoop displacement transducer is installed, and can be guaranteed real-time transmission data;

Step 302, control servocontrol rock implosion test machine, cylindrical rock sample is carried out the circulation of axial stress overall process add the unloading test, in the test before arriving the rock sample peak strength, the load phase of servocontrol rock implosion test machine is pressed displacement control mode control, and unloading phase adopts axial stress control, when the axial stress of cylindrical rock sample more than or equal to cylindrical rock sample peak strength 80 ~ 90% the time, unloading phase adopts displacement control, and load phase also adopts displacement control;

Step 303, set cycle index and mode that above-mentioned axial stress overall process circulation adds the unloading test, wherein to add the cycle index of unloading test be 15 ~ 20 times for axial stress overall process circulation, during each unloading, axially deviatoric stress is offloaded to 0.1MPa, then begin to load, guarantee continuity and the integrality of process of the test;

Step 304, apply confined pressure to a certain predetermined value, keep confined pressure constant, cylindrical rock sample is carried out the circulation of axial stress overall process add the unloading test, wherein in 30% of cylindrical rock sample peak previous peaks intensity, 40%, 50%, 60% and 70% respectively once circulates adds unloading, 80% of peak strength, 85%, 90%, 95% and 100% respectively once circulates adds unloading, descending branch is carried out 4 ~ 6 circulations and is added unloading behind the peak of cylindrical rock sample peak value, the residual strength section is carried out 3 ~ 4 circulations and is added unloading behind the peak of cylindrical rock sample peak value, record confined pressure, each adds unloading circulation maximum axial stress, axial displacement and lateral shift parameter, as shown in Figure 1;

Step 401 is according to elastic modulus

, Poisson ratio

, bulk modulus , modulus of shearing

Calculate above-mentioned each circulation and add unloading rock deformation parameter value, wherein, Δ σ ₁, Δ ε ₁, Δ ε ₃Represent respectively axial stress increment, axial strain increment and the lateral strain increment of one section of the 5 ~ 10MPa of whenever being separated by in the loading section that above-mentioned each circulation adds unloading; Δ σ _m, Δ ε _m, Δ τ ₈, Δ γ ₈Represent respectively mean normal stress increment, average normal strain increment, octahedral shear stress increment and the octohedral shear strain increment of one section of the 5 ~ 10MPa of whenever being separated by in the loading section that above-mentioned each circulation adds unloading; Add the axial plastic strain ε that obtains cylindrical rock sample the unloading test from above-mentioned axial stress overall process circulation ₁ ^pWith side direction plastic strain ε ₃ ^p, then according to generalized plasticity strain formula

Calculate each the circulation and add the generalized plasticity strain of unloading; Add the elastic modulus that unloading obtains with circulate at every turn , Poisson ratio

, bulk modulus

And modulus of shearing

Parameter is depicted as respectively curve map with corresponding generalized plasticity strain, obtain the Changing Pattern of these deformation parameters and generalized plasticity strain by above-mentioned curve map, and can obtain the value of corresponding elastic modulus, Poisson ratio, bulk modulus and modulus of shearing, wherein, elastic modulus-generalized plasticity strain curve as shown in Figure 2, Poisson ratio-the generalized plasticity strain curve is as shown in Figure 3;

Step 402, each corresponding with the generalized plasticity strain facies under the different confined pressures added unloading circulation maximum axial stress be depicted as curve map, as shown in Figure 4, adopt interpolation method obtain under the different confined pressures identical generalized plasticity strain corresponding each add unloading circulation maximum axial stress, and adopt mole-enclosed pasture yield criteria, return and obtain cohesive strength c corresponding to this generalized plasticity strain and angle of internal friction

Value increases the generalized plasticity strain value, analogizes one by one, can obtain many group corresponding cohesive strength c of different generalized plasticity strains and angle of internal friction

Value is with cohesive strength c and angle of internal friction Value is depicted as respectively curve map with corresponding generalized plasticity strain, by this curve description cohesive strength c and angle of internal friction

With the Changing Pattern of generalized plasticity strain, shown in Fig. 6 and 5, and obtain corresponding cohesive strength c and angle of internal friction Value.

In the step 302 of technique scheme, in the test before arriving the rock sample peak strength, the load phase of servocontrol rock implosion test machine is pressed displacement control mode control, the rate of displacement of its loading is 0.001mm/s, unloading phase adopts axial stress control, and the unloading rate of stressing is 0.1MPa/s; When the axial stress of cylindrical rock sample more than or equal to cylindrical rock sample peak strength 80 ~ 90% the time, unloading phase adopts displacement control, rate of debarkation is 0.01mm/s, load phase also adopts displacement control, loading speed is 0.01mm/s.

In the step 304 of technique scheme, the predetermined range that applies confined pressure is 5MPa ~ 40MPa.

In the step 1 of technique scheme, the buried hard rock core that drills through is processed into diameter and aspect ratio is the cylindrical rock sample of 1:2.The diameter of this cylindrical rock sample is 50mm, highly for 100mm.

The step 2 of technique scheme comprises the steps:

Step 2.1, carrying out before axial stress overall process circulation adds unloading test, engineering zone terrestrial stress value according to actual measurement or inverting acquisition, design at least 4 kinds of confined pressure predetermined values, every kind of required rock sample of confined pressure is 3 ~ 5, guarantee the reliability of test findings, be convenient to utilize mole-enclosed pasture yield criteria to obtain cohesive strength and the angle of internal friction equal strength parameter of rock;

Step 2.2, according to the confined pressure of setting, carry out the normal triaxial load test of cylindrical rock sample under the different confined pressures, the peak strength of the cylindrical rock sample that obtains when different confined pressure predetermined value is so that definite axial stress overall process circulation adds the axial stress value when unloading beginning when unloading test at every turn.

Above-mentioned formulation process is as follows: hard rock is comprised of elastic deformation and plastic yield in the distortion that the circulation of axial stress overall process adds in the unloading test.For elastic deformation, but according to law recklessly:

${{\mathrm{\ϵ}}_1}^e=\frac{1}{E}[{\mathrm{\σ}}_1-v({\mathrm{\σ}}_2+{\mathrm{\σ}}_3)]---\left(1\right)$

${{\mathrm{\ϵ}}_2}^e=\frac{1}{E}[{\mathrm{\σ}}_2-v({\mathrm{\σ}}_1+{\mathrm{\σ}}_3)]---\left(2\right)$

${{\mathrm{\ϵ}}_3}^e=\frac{1}{E}[{\mathrm{\σ}}_3-v({\mathrm{\σ}}_1+{\mathrm{\σ}}_2)]---\left(3\right)$

ε in the formula ₁ ^e, ε ₂ ^e, ε ₃ ^eRepresent the principal strain under the elastic stage, σ ₁, σ ₂, σ ₃Represent principle stress, E represents elastic modulus, and v represents Poisson ratio.

Add the unloading circulation for each, E and v have in the linear elasticity section value that loads the position

$E=\frac{{\mathrm{\Δ\σ}}_1}{{\mathrm{\Δ\ϵ}}_1}---\left(4\right)$

And $v=\left|\frac{{\mathrm{\Δ\ϵ}}_3}{{\mathrm{\Δ\ϵ}}_1}\right|---\left(5\right)$

, ε in the formula _mRepresent average normal strain, σ _mRepresent mean normal stress, K is bulk modulus, wherein ε _mAnd σ _mCalculating formula is as follows respectively:

${\mathrm{\ϵ}}_m=\frac{1}{3}({\mathrm{\ϵ}}_1+{\mathrm{\ϵ}}_2+{\mathrm{\ϵ}}_3)---\left(6\right)$

Wherein, ε, ε ₂, ε ₃Represent the principal strain of three directions.

${\mathrm{\σ}}_m=\frac{1}{3}({\mathrm{\σ}}_1+{\mathrm{\σ}}_2+{\mathrm{\σ}}_3)---\left(7\right)$

Add the unloading circulation for each, K has in the linear elasticity section value that loads the position

$K=\frac{{\mathrm{\Δ\σ}}_m}{3{\mathrm{\Δ\ϵ}}_m}---\left(8\right)$

τ ₈=G γ ₈, τ in the formula ₈Be octahedral shear stress, γ ₈Be octohedral shear strain, G is shear elasticity, wherein τ ₈And γ ₈Calculating formula is as follows respectively:

${\mathrm{\τ}}_8=\frac{1}{3}\sqrt{[{({\mathrm{\σ}}_1-{\mathrm{\σ}}_2)}^2+{({\mathrm{\σ}}_2-{\mathrm{\σ}}_3)}^2+{({\mathrm{\σ}}_3-{\mathrm{\σ}}_1)}^2]}---\left(9\right)$

${\mathrm{\γ}}_8=\frac{1}{3}\sqrt{[{({\mathrm{\ϵ}}_1-{\mathrm{\ϵ}}_2)}^2+{({\mathrm{\ϵ}}_2-{\mathrm{\ϵ}}_3)}^2+{({\mathrm{\ϵ}}_3-{\mathrm{\ϵ}}_1)}^2]}---\left(10\right)$

Add the unloading circulation for each, G has in the linear elasticity section value that loads the position

$G=\frac{{\mathrm{\Δ\τ}}_8}{{\mathrm{\Δ\γ}}_8}---\left(11\right)$

Record adds unloading circulation at every turn finish after the axial plastic strain ε of correspondence ₁ ^eWith side direction plastic strain ε ₃ ^e, utilize generalized plasticity strain computing formula

$\stackrel{\‾}{{\mathrm{\ω}}^p}=\frac{2}{3}({{\mathrm{\ϵ}}_1}^p-{{\mathrm{\ϵ}}_2}^p)---\left(12\right)$

Obtain the generalized plasticity strain that the circulation of axial stress overall process adds unloading test, can obtain elastic modulus-generalized plasticity strain, Poisson ratio-generalized plasticity strain, bulk modulus-generalized plasticity strain, the modulus of shearing-curve maps such as generalized plasticity strain, select suitable mathematical model to describe respectively the Changing Pattern of these deformation parameters and generalized plasticity strain, and can obtain the value of corresponding deformation parameter.

Each corresponding with the generalized plasticity strain facies under the different confined pressures added unloading circulation maximum axial stress be depicted as curve map, adopt interpolation method to obtain the corresponding axial stress of identical generalized plasticity strain under the different confined pressures, adopt mole-enclosed pasture yield criteria formula

, τ is corresponding to the shear stress on the cylindrical rock sample destruction face in the formula, and σ is corresponding to the normal stress on the cylindrical rock sample destruction face,

Be angle of internal friction, c is cohesive strength, and wherein the computing formula of τ and σ is as follows respectively

The method that adopt to return, calculate c corresponding to identical generalized plasticity strain and , increase the generalized plasticity strain value, analogize one by one, can obtain many group corresponding cohesive strength c of different generalized plasticity strains and angle of internal friction

Value is with cohesive strength c and angle of internal friction

Value is depicted as respectively curve map with corresponding generalized plasticity strain, selects suitable mathematical model to describe respectively cohesive strength c and angle of internal friction

With the Changing Pattern of generalized plasticity strain, and can obtain the value of respective strengths parameter.

The content that instructions is not described in detail belongs to the known prior art of this area professional and technical personnel.

Claims (6)

1. the assay method of a buried hard rock mechanics parameter Changing Pattern and value is characterized in that it comprises the steps:

Step 1: drill through at the scene buried hard rock core, and the hard rock core is processed into cylindrical rock sample;

Step 2: above-mentioned cylindrical rock sample is carried out three axles loading test, and set the confined pressure predetermined value in the three axles loading test, thereby obtain the peak strength of cylindrical rock sample when different confined pressure predetermined value;

Step 301, the cylindrical rock sample that step 1 is obtained is installed on the servocontrol rock implosion test machine, at this cylindrical rock sample shaft position sensor and hoop displacement transducer is installed, and can be guaranteed real-time transmission data;

Step 302, control servocontrol rock implosion test machine, cylindrical rock sample is carried out the circulation of axial stress overall process add the unloading test, in the test before arriving the rock sample peak strength, the load phase of servocontrol rock implosion test machine is pressed displacement control mode control, and unloading phase adopts axial stress control, when the axial stress of cylindrical rock sample more than or equal to cylindrical rock sample peak strength 80 ~ 90% the time, unloading phase adopts displacement control, and load phase also adopts displacement control;

Step 303, set cycle index and mode that above-mentioned axial stress overall process circulation adds the unloading test, wherein to add the cycle index of unloading test be 15 ~ 20 times for axial stress overall process circulation, during each unloading, axially deviatoric stress is offloaded to 0.1MPa, then begin to load, guarantee continuity and the integrality of process of the test;

Step 304, apply confined pressure to a certain predetermined value, keep confined pressure constant, cylindrical rock sample is carried out the circulation of axial stress overall process add the unloading test, wherein in 30% of cylindrical rock sample peak previous peaks intensity, 40%, 50%, 60% and 70% respectively once circulates adds unloading, 80% of peak strength, 85%, 90%, 95% and 100% respectively once circulates adds unloading, descending branch is carried out 4 ~ 6 circulations and is added unloading behind the peak of cylindrical rock sample peak value, the residual strength section is carried out 3 ~ 4 circulations and is added unloading behind the peak of cylindrical rock sample peak value, records confined pressure, each adds unloading circulation maximum axial stress, axial displacement and lateral shift parameter;

Step 401 is according to elastic modulus

, Poisson ratio

, bulk modulus

, modulus of shearing

Calculate above-mentioned each circulation and add unloading rock deformation parameter value, wherein, Δ σ ₁, Δ ε ₁, Δ ε ₃Represent respectively axial stress increment, axial strain increment and the lateral strain increment of one section of the 5 ~ 10MPa of whenever being separated by in the loading section that above-mentioned each circulation adds unloading; Δ σ _m, Δ ε _m, Δ τ ₈, Δ γ ₈Represent respectively mean normal stress increment, average normal strain increment, octahedral shear stress increment and the octohedral shear strain increment of one section of the 5 ~ 10MPa of whenever being separated by in the loading section that above-mentioned each circulation adds unloading; Add the axial plastic strain ε that obtains cylindrical rock sample the unloading test from above-mentioned axial stress overall process circulation ₁ ^pWith side direction plastic strain ε ₃ ^p, then according to generalized plasticity strain formula

Calculate each the circulation and add the generalized plasticity strain of unloading; Add the elastic modulus that unloading obtains with circulate at every turn

, Poisson ratio

, bulk modulus

And modulus of shearing

Parameter is depicted as respectively curve map with corresponding generalized plasticity strain, obtains the Changing Pattern of these deformation parameters and generalized plasticity strain by above-mentioned curve map, and can obtain the value of corresponding elastic modulus, Poisson ratio, bulk modulus and modulus of shearing;

Step 402, each corresponding with the generalized plasticity strain facies under the different confined pressures added unloading circulation maximum axial stress be depicted as curve map, adopt interpolation method obtain under the different confined pressures identical generalized plasticity strain corresponding each add unloading circulation maximum axial stress, and adopt mole-enclosed pasture yield criteria, return and obtain cohesive strength c corresponding to this generalized plasticity strain and angle of internal friction

Value increases the generalized plasticity strain value, analogizes one by one, can obtain many group corresponding cohesive strength c of different generalized plasticity strains and angle of internal friction

Value is with cohesive strength c and angle of internal friction

Value is depicted as respectively curve map with corresponding generalized plasticity strain, by this curve description cohesive strength c and angle of internal friction

With the Changing Pattern of generalized plasticity strain, and obtain corresponding cohesive strength c and angle of internal friction

Value.

2. the assay method of buried hard rock mechanics parameter Changing Pattern according to claim 1 and value, it is characterized in that: in the described step 302, in the test before arriving the rock sample peak strength, the load phase of servocontrol rock implosion test machine is pressed displacement control mode control, the rate of displacement of its loading is 0.001mm/s, unloading phase adopts axial stress control, and the unloading rate of stressing is 0.1MPa/s; When the axial stress of cylindrical rock sample more than or equal to cylindrical rock sample peak strength 80 ~ 90% the time, unloading phase adopts displacement control, rate of debarkation is 0.01mm/s, load phase also adopts displacement control, loading speed is 0.01mm/s.

3. the assay method of buried hard rock mechanics parameter Changing Pattern according to claim 1 and value, it is characterized in that: in the described step 304, the predetermined range that applies confined pressure is 5MPa ~ 40MPa.

4. the assay method of buried hard rock mechanics parameter Changing Pattern according to claim 1 and value is characterized in that: in the described step 1, the buried hard rock core that drills through is processed into diameter and aspect ratio is the cylindrical rock sample of 1:2.

5. the assay method of buried hard rock mechanics parameter Changing Pattern according to claim 4 and value is characterized in that: the diameter of described cylindrical rock sample is 50 mm, highly is 100mm.

6. the assay method of buried hard rock mechanics parameter Changing Pattern according to claim 1 and value, it is characterized in that: described step 2 comprises the steps:

Step 2.1, carrying out before axial stress overall process circulation adds unloading test, engineering zone terrestrial stress value according to actual measurement or inverting acquisition, design at least 4 kinds of confined pressure predetermined values, every kind of required rock sample of confined pressure is 3 ~ 5, is convenient to utilize mole-enclosed pasture yield criteria to obtain cohesive strength and the angle of internal friction equal strength parameter of cylindrical rock sample;

Step 2.2, according to the confined pressure of setting, carry out the normal triaxial load test of cylindrical rock sample under the different confined pressures, the peak strength of the cylindrical rock sample that obtains when different confined pressure predetermined value is so that definite axial stress overall process circulation adds the axial stress value when unloading beginning when unloading test at every turn.

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