CN108318351A - A kind of test method for testing rock shearing mechanical property under normal direction Excavation - Google Patents
A kind of test method for testing rock shearing mechanical property under normal direction Excavation Download PDFInfo
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- CN108318351A CN108318351A CN201810007660.0A CN201810007660A CN108318351A CN 108318351 A CN108318351 A CN 108318351A CN 201810007660 A CN201810007660 A CN 201810007660A CN 108318351 A CN108318351 A CN 108318351A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/24—Investigating strength properties of solid materials by application of mechanical stress by applying steady shearing forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0014—Type of force applied
- G01N2203/0025—Shearing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
- G01N2203/0075—Strain-stress relations or elastic constants
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/025—Geometry of the test
- G01N2203/0258—Non axial, i.e. the forces not being applied along an axis of symmetry of the specimen
Abstract
The present invention relates to a kind of test methods of rock shearing mechanical property under test normal direction Excavation, during experiment, vertical and horizontal pressure head is set to be contacted with shear box first, then apply normal stress to initial normal stress design value, apply shear stress again to initial shear stress design value, normal stress is finally unloaded until sample is destroyed with constant speed, before sample failure by shear, normal stress is gradually reduced and shear stress remains unchanged.This method load mode is simple and practicable, it being capable of shear fracture caused by simulation rock off-load, the intensity and deformation behaviour of rock under normal direction Excavation can be obtained using this method, understand peculiar shearing mechanical property of the rock under Excavation, theoretical foundation is provided for engineering rock mass stability control and unstability early warning.
Description
Technical field
The present invention relates to rock shearing mechanical properties under rock mechanics field more particularly to a kind of test normal direction Excavation
Test method.
Background technology
In underground chamber, slope excavating and valley trenching etc. artificially and under effect of natural environment, rock mass generates strong off-load and makees
With thus the disasters such as caused wall rock destabilization, landslide even rock burst often occur.Behavior Under Unloading Condition is that engineering rock mass damage is very heavy
The form wanted.Due to the heterogeneous discontinuous feature of rock, intensity and deformation behaviour tool of the rock under off-load and loading effect
There are significant difference, i.e. stress path that can influence the mechanical behavior of rock.Therefore, for the mechanical behavior of rock under Excavation
Research be very necessary, scholars have done a large amount of research work in the field.
Mostly using three axis unloader tests to the research of rock Unloading Mechanics behavior at present, (Zhang Liming, Wang Quan, Sun Hui wait
Deformation behaviour and constitutive model [J] coal journals of Rock Behavior Under Unloading Condition, 2009 (12):1626-1631.), three axis off-loads examination
Proved recipe method is broadly divided into two steps：(1) it loads confining pressure and axis is depressed into desired value；(2) unloading confining pressure is until sample destruction.Three axis off-loads
The main study subject of experiment is off-load compressive strength, deformation and the energy dissipation of rock.However, either still being unloaded in load
Under the conditions of lotus, the failure by shear of rock is its important failure mode always, and the shearing mechanical behavior of rock is that rock mechanics is closed
One of emphasis of note.It is unable to the shear fracture under simulation rock Excavation using three axis unloader tests, needs to propose a kind of energy
The method of enough simulation rock Excavation down cut ruptures, studies rock Excavation down cut mechanical behavior.
Invention content
The purpose of the present invention is to propose to a kind of test methods of rock shearing mechanical property under test normal direction Excavation.It should
Method load mode is simple and practicable, can shear fracture caused by simulation rock off-load, normal direction can be obtained using this method and unloaded
The intensity and deformation behaviour of rock under the conditions of lotus understand peculiar shearing mechanical property of the rock under Excavation, are engineering rock
Body stability control and unstability early warning provide theoretical foundation.
The technical scheme is that：A kind of test method for testing rock shearing mechanical property under normal direction Excavation,
During experiment, vertical and horizontal pressure head is made to be contacted with shear box first, then applies normal stress to initial normal stress and set
Evaluation, then apply shear stress to initial shear stress design value, normal stress is finally unloaded until sample destruction, examination with constant speed
Before sample failure by shear, normal stress is gradually reduced and shear stress remains unchanged.
Include the following steps：
A. cutting polishing rock sample；
B. rock sample is placed in shear, shear is placed in shear testing maschine and prepares to load；
C. the vertical pressure head of shear testing maschine is adjusted, vertical loading system applies normal force by vertical pressure head to sample,
Vertical pressure head is set to be contacted with shear box；
D. the horizontal pressure head of shear testing maschine is adjusted, horizontal addload system, which is applied by horizontal pressure head to sample, to be sheared, and is made
Horizontal pressure head is contacted with shear box；
E. Stress Control pattern is used, applies normal stress to initial normal stress design value σni, and remain unchanged；
F. Stress Control pattern is used, applies shear stress to initial shear stress design value τni, and remain unchanged；
G. Stress Control pattern is used to unload normal stress, until sample destroys；
H. after sample destroys, testing machine loading system is closed immediately.When loading system is closed, horizontal addload system should be first closed
System, is then shut off vertical loading system.
Setting at least five groups of initial shear stress are tested, and repeat the above steps b- step h, the result of at least five groups experiments
By fitting a straight line, strength envelope is obtained.
The sample is cuboid sample, and sample machining accuracy and surface smoothness meet GB standard；
The size of normal force and shearing applied in step c and step d is 0.1kN.
Compared with prior art, the beneficial effects of the invention are as follows：
The present invention is suitable for simulating the experiment of rock shearing mechanical behavior under normal direction Excavation；It is tried with traditional three axis off-loads
It tests lower rock compressed and destroys difference, using the test method of rock shearing mechanical behavior under above-mentioned test normal direction Excavation, energy
The normal stress and shear stress state and rock unloading shear destructive process that enough simulation rocks are born before destroying；It can obtain not
With rock failure mechanism of rock normal stress under stress condition, rock shear strength and primary stress relationship under Excavation, under Excavation
Rock Normal Displacement and cut change in displacement rule.By this experimental method, engineering rock mass rock off-load item can be become more apparent upon
Shearing mechanical behavior under part recognizes rock strength and deformation behaviour under Excavation, is underground engineering, slope excavating and river valley
Rock Mass Unloading unstability caused by incision etc. provides early warning and control is suggested.
Description of the drawings
Fig. 1 be during experiment normal stress and shear stress plus uninstall process schematic diagram；
Fig. 2 is test model stress time curve；
Fig. 3 is test sample displacement-time curve；
Fig. 4 is test sample intensity and strength envelope.
In figure, normal stress 1, shear stress 2, initial normal stress 3, initial shear stress 4, Normal Displacement 5 cuts displacement 6, anti-
Cut strength test value 7, strength envelope 8.
Specific implementation mode
In order to keep the purpose of the present invention and technical solution clearer, in conjunction with the accompanying drawings and embodiments to the present invention into advance one
The explanation of step, but should not be construed the above-mentioned subject area of the present invention and be only limitted to following embodiments.Not departing from, the present invention is above-mentioned
In the case of technological thought, according to ordinary skill knowledge and customary means, various replacements and change are made, should all include
Within the scope of the present invention.
The present invention tests the test method (abbreviation method) of rock shearing mechanical property under normal direction Excavation, includes mainly
Following steps：
A., collected Rock cutting is polished into the cuboid sample of Pass Test standard first；
B. the sample polished is placed in shear, shear is placed in shear testing maschine and prepares to add
It carries；
C. the vertical pressure head for adjusting shear testing maschine, applies the normal force of 0.1kN by vertical pressure head to sample, makes vertical
Pressure head is contacted with shear box；
D. the horizontal pressure head of shear testing maschine is adjusted, applies the shearing of 0.1kN to sample by horizontal pressure head, makes horizontal pressure head
It is contacted with shear box；
E. Stress Control pattern is used, applies normal stress 1 to initial normal stress 3, and remain unchanged, specifically applied
Journey as shown in Figure 1,
F. Stress Control pattern is used, applies shear stress 2 to initial shear stress 4, and remain unchanged, it is specific to apply process such as
Shown in Fig. 1；
G. Stress Control pattern is used to unload normal stress, normal stress when sample destroys, and record destroys
And shearing strength, while exporting the Normal Displacement of rock under normal direction Excavation and cutting displacement；Corresponding shear stress when destruction
For the off-load shearing strength of sample；
H. after sample destroys, testing machine loading system is closed immediately.When loading system is closed, horizontal addload system should be first closed
System, is then shut off vertical loading system.
Setting at least five groups of initial shear stress are tested, and the b-h processes are repeated, and at least five groups of experiments are quasi- by straight line
It closes, obtains strength envelope.
The sample is cuboid sample, and sample machining accuracy and surface smoothness meet GB standard；
Shearing mechanical property in the application refers to cutting displacement, Normal Displacement, destroying under normal stress and off-load under off-load
Shearing strength.The present invention can carry out grinding for the shearing mechanical behavior under rock normal direction Excavation by adding uninstall process
Study carefully.
Normal stress 1 and shear stress 2 are applied to initial design values come before simulation rock off-load by control in the present invention
Stress, one smaller power of application makes shear box pressure head corresponding with shear testing maschine contact during this, this is smaller
Power rule of thumb value, principle are the intensity of far smaller than sample.In unloading process, the normal stress 1 that sample is born is gradual
Reduce, and shear stress 2 remains unchanged, and until sample destruction, restores unloading shear rupture process caused by engineering excavation.Sample accords with
GB standard is closed, Stress Control, loading velocity meet GB standard, and unloding speed simulates work according to the practical progress value of engineering
The practical unloading conditions of Cheng Yanti.
The shear is identical as traditional direct shear test shear, including upper and lower shear box and antifriction apparatus.
Initial normal stress design value σ in the present inventionni, initial shear stress design value τniRule of thumb design, it is different
The different rocks tested needed for experimental evidence are selected accordingly, and sample may not destroy initial value value at that time,
It needs to redesign initial value, repeats experiment process.
Embodiment：
It is main to wrap present embodiment discloses a kind of test method of rock shearing mechanical property under test normal direction Excavation
Include following steps：
A., collected Rock cutting is polished into the cuboid sample of Pass Test standard first；
B. the sample polished is placed in shear, shear is placed in shear testing maschine and prepares to add
It carries；
C. the vertical pressure head for adjusting shear testing maschine, applies the normal force of 0.1kN by vertical pressure head to sample, makes vertical
Pressure head is contacted with shear box；
D. the horizontal pressure head for adjusting shear testing maschine, is applied the shearing of 0.1kN to sample by horizontal pressure head, makes horizontal pressure
Head is contacted with shear box；
E. Stress Control pattern is used, applies normal stress 1 to initial normal stress 3, initial normal stress 3 is 24MPa,
And remain unchanged, loading speed 0.05kN/s, specific application process is as shown in Figure 2；
F. Stress Control pattern is used, applies shear stress 2 to initial shear stress 4, initial shear stress 4 is 15MPa, and is kept
Constant, it is as shown in Figure 2 specifically to apply process by loading speed 0.05kN/s；
G. Stress Control pattern is used to unload normal stress with constant rate of speed, until sample destroys, rate of debarkation is
0.05kN/s；
H. after sample destroys, testing machine loading system is closed immediately, and normal stress is 8.5MPa when sample destroys.
Through this embodiment, shear testing maschine automatically records data, obtains Normal Displacement 5 under the conditions of unloading shear
With cut 6 versus time curve of displacement as shown in figure 3, obtaining corresponding shearing strength when initial shear stress is 15MPa simultaneously
Test value 7.
15,17,19,21 and 23MPa, five groups of initial shear stress 4 are arranged in the present embodiment altogether, repeat step b-h respectively,
The shearing strength test value 7 under five Excavations is obtained, carrying out fitting a straight line to this five data obtains loosening strength envelope
Line 8, as shown in Figure 4.
The Normal Displacement of rock under normal direction Excavation has been obtained through this embodiment and cuts displacement in adding uninstall process
Change curve, the shearing strength and strength envelope of rock under normal direction Excavation.To engineering rock mass estimation of stability and control
Fixture has important directive significance.Apparent raising is had before the rock failure mechanism of rock for example, cutting displacement and increasing rate, this is carried for landslide
Method for early warning is supplied.
The present invention does not address place and is suitable for the prior art.
Claims (4)
1. the test method of rock shearing mechanical property under a kind of test normal direction Excavation, this approach includes the following steps：
A. cutting polishing rock sample；
B. rock sample is placed in shear, shear is placed in shear testing maschine and prepares to load；
C. the vertical pressure head of shear testing maschine is adjusted, vertical loading system applies normal force to sample by vertical pressure head, makes to erect
It is contacted to pressure head with shear box；
D. the horizontal pressure head of shear testing maschine is adjusted, horizontal addload system, which is applied by horizontal pressure head to sample, to be sheared, and level is made
Pressure head is contacted with shear box；
E. Stress Control pattern is used, applies normal stress to initial normal stress design value σni, and remain unchanged；
F. Stress Control pattern is used, applies shear stress to initial shear stress design value τni, and remain unchanged；
G. Stress Control pattern is used to unload normal stress, until sample destroys；
H. after sample destroys, testing machine loading system is closed immediately.
2. the test method of rock shearing mechanical property, feature under test normal direction Excavation according to claim 1
It is：Setting at least five groups of initial shear stress are tested, and repeat the above steps b- step h, and the result of at least five groups experiments is logical
Fitting a straight line is crossed, strength envelope is obtained.
3. the test method of rock shearing mechanical property, feature under test normal direction Excavation according to claim 1
It is：Sample in the step a is cuboid sample.
4. according to the test method of rock shearing mechanical property under any test normal direction Excavations of claim 1-3,
It is characterized in that：The size of normal force and shearing applied in step c and step d is 0.1kN.
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| CN201810007660.0A CN108318351B (en) | 2018-01-04 | 2018-01-04 | Test method for testing rock shearing mechanical property under normal unloading condition |
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| CN201810007660.0A CN108318351B (en) | 2018-01-04 | 2018-01-04 | Test method for testing rock shearing mechanical property under normal unloading condition |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112268817A (en) * | 2020-10-26 | 2021-01-26 | 长安大学 | Rock shear fracture judging method in normal unloading direct shear test |
| CN112611770A (en) * | 2020-11-30 | 2021-04-06 | 中国矿业大学 | Rock three-dimensional fracture network unloading shearing and deformation testing device and method |
| CN112683692A (en) * | 2020-12-02 | 2021-04-20 | 河北工业大学 | Multifunctional large-size shear test device and test method thereof |
| CN114778301A (en) * | 2022-06-17 | 2022-07-22 | 煤炭科学研究总院有限公司 | Rock mass stability determination method and device and electronic equipment |
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| CN1619285A (en) * | 2004-10-29 | 2005-05-25 | 成都理工大学 | Portable rock mechanic multifunction testing instrument |
| CN1632510A (en) * | 2004-11-26 | 2005-06-29 | 成都理工大学 | Direct shear test machine for rock |
| CN204086017U (en) * | 2014-09-29 | 2015-01-07 | 湖南科技大学 | A kind of rock twin shaft unloader test device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112268817A (en) * | 2020-10-26 | 2021-01-26 | 长安大学 | Rock shear fracture judging method in normal unloading direct shear test |
| CN112268817B (en) * | 2020-10-26 | 2024-04-09 | 长安大学 | Rock shearing fracture discrimination method in normal unloading direct shear test |
| CN112611770A (en) * | 2020-11-30 | 2021-04-06 | 中国矿业大学 | Rock three-dimensional fracture network unloading shearing and deformation testing device and method |
| CN112683692A (en) * | 2020-12-02 | 2021-04-20 | 河北工业大学 | Multifunctional large-size shear test device and test method thereof |
| CN114778301A (en) * | 2022-06-17 | 2022-07-22 | 煤炭科学研究总院有限公司 | Rock mass stability determination method and device and electronic equipment |
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| CN108318351B (en) | 2020-06-23 |
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