CN109959563A - A kind of p test methods such as high-precision frozen soil - Google Patents

A kind of p test methods such as high-precision frozen soil Download PDF

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Publication number
CN109959563A
CN109959563A CN201711336520.XA CN201711336520A CN109959563A CN 109959563 A CN109959563 A CN 109959563A CN 201711336520 A CN201711336520 A CN 201711336520A CN 109959563 A CN109959563 A CN 109959563A
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China
Prior art keywords
test
precision
frozen soil
strain
level
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Pending
Application number
CN201711336520.XA
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Chinese (zh)
Inventor
刘万福
张海宁
曹阳
曹春诚
晨光
张松
徐湘田
白瑞强
杨宗维
张伟东
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Inner Mongolia East Power Design Co Ltd
State Grid Corp of China SGCC
Inner Mongolia University
Economic and Technological Research Institute of State Grid Inner Mongolia Electric Power Co Ltd
State Grid Eastern Inner Mongolia Power Co Ltd
Original Assignee
Inner Mongolia East Power Design Co Ltd
State Grid Corp of China SGCC
Inner Mongolia University
Economic and Technological Research Institute of State Grid Inner Mongolia Electric Power Co Ltd
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Application filed by Inner Mongolia East Power Design Co Ltd, State Grid Corp of China SGCC, Inner Mongolia University, Economic and Technological Research Institute of State Grid Inner Mongolia Electric Power Co Ltd filed Critical Inner Mongolia East Power Design Co Ltd
Priority to CN201711336520.XA priority Critical patent/CN109959563A/en
Publication of CN109959563A publication Critical patent/CN109959563A/en
Pending legal-status Critical Current

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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02Details
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/08Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • G01N3/18Performing tests at high or low temperatures
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0014Type of force applied
    • G01N2203/0016Tensile or compressive
    • G01N2203/0019Compressive
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02Details not specific for a particular testing method
    • G01N2203/022Environment of the test
    • G01N2203/0222Temperature
    • G01N2203/0228Low temperature; Cooling means

Abstract

The invention discloses a kind of methods for realizing the p such as high-precision frozen soil test, comprising: frozen soil sample is put into low temperature triaxial apparatus pressure chamber by (a), is consolidated under given confining pressure;(b) correction area is first calculated every level-one axle power is arranged by axial strain, realizes approximate equal p test, body strain is calculated after load, correction area is calculated according to axial strain and body strain, obtains actual mean stress p;(c) whether the p investigated in step (b) is constant in precision allowed band, if so, off-test, otherwise uses high-precision Function Fitting axial strain ε1With the relationship of specimen cross sectional area A;(d) according to ε obtained by step (c)1Every level-one axle power is arranged in the relationship of-A and confining pressure carries out waiting p test, calculates true cross-sectional area and p after the test, if p may be regarded as constant in precision allowed band, which is equal p test, otherwise according to new ε1- A relationship carries out equal p test again, iterates, until resulting p value may be regarded as constant.

Description

A kind of p test methods such as high-precision frozen soil
Technical field:
The invention belongs to the technical fields of soil test, and in particular to be one kind in frozen soil realize high-precision etc. p examination The method tested provides new test side to investigate mechanical behavior and Constitutive Model of Frozen Soil verifying of the frozen soil under complicated stress environment Method
Background technique:
Equal p test refers to the holding mean stress p=(σ in Geotechnical materials triaxial test123)/3 are the examination of constant It tests, which can be used for investigating influence of the equivalent shear stress to rock-soil material deformation characteristic under different p values, it can also be used to rock The verifying of soil material constitutive model, in certain elastic-plastic constitutive relations for melting soil, need with etc. p test test result come true Determine yield surface and hardening law.Currently, outer in addition to carrying out the p such as minority test in melting soil, not yet there are equal p to try in frozen soil The report tested, and melt and not yet consider body strain in axle power setting in the equal p test in soil, test accuracy is restricted.Freeze Soil is by ice, does not freeze water, a kind of special soil body of soil particle and gas composition, group structure complexity, mechanical behavior by temperature plus The influence of the factors such as rate, stress condition is carried, mainly applies two kinds of simple stress roads of uniaxial compression and mechanical property at present Diameter is tested to investigate its mechanical property, it is difficult to understand its deformation and failure rule under locating complex stress condition in practical projects Rule, and Accurate Prediction and description frozen soil are also difficult in complex stress by being fitted resulting Constitutive Model of Frozen Soil under simple stress path Mechanical behavior under path.With the deep development of frozen soil engineering and frozen soil mechanics research, it is multiple to need equal p test of exploitation etc. Frozen soil mechanics test method under miscellaneous stress path investigates the mechanical property of frozen soil comprehensively and establishes reasonable this structure of frozen soil mould Type.
Summary of the invention:
The present invention lacks the status of complicated stress environment test in order to change in frozen soil mechanics test method, provide one kind The p test method such as high-precision frozen soil.The present invention is the mechanical behavior investigated frozen soil under complicated stress environment and the modeling of frozen soil bullet Property constitutive model provide a kind of new test method.This method considers body in specimen cross sectional area amendment and axle power setting Strain does not consider that body strain has higher test accuracy than melting in the p such as soil test, and principle and step can be applied to The frozen soil mechanics of other any straight line stress paths is tested, and corresponding test method also can be applied to melt soil.
The realization of the object of the invention is completed by following technical scheme:
A kind of pair of frozen soil realizes the accurate method for waiting p test, it is characterised in that this method comprises:
Step 1: frozen soil sample is put into low temperature triaxial apparatus when test, confining pressure is applied to the p examinations such as test objective value carries out It tests;
Step 2: according to axial strain ε1Much larger than body strain εvThe fact, every level-one is only calculated with axial strain first The cross-sectional area of frozen soil sample calculates the cross-sectional area of every level-one frozen soil sample, thus by Δ p=Δ F/A+2 Δ σ3=0 really The axle power increment △ F and corresponding confining pressure increment Delta σ of fixed every level-one3To carry out equal p test;
Step 3: calculating body strain ε using the test result in second stepv, then axial strain and bulk strain are used simultaneously The true cross-sectional area A of sample in second step test is calculated, and by p=(F/A+2 σ3)/3 calculate entire test process In mean stress p value;
If constant can be regarded as in precision allowed band by calculating resulting p value, the test in second step can be made For the enough equal p tests of precision;It, can be according to second step if the value of p changes greatly during the test cannot be considered as constant Test result is with high-precision Function Fitting shaft to strain stress1With the relationship of specimen cross sectional area A.
Step 4: the ε according to obtained in third step1The A of every level-one is arranged in~A relationship, and the Δ of every level-one is thus arranged F、Δσ3Carry out equal p test.
True A and p is calculated after the test, if the variation of p value can be regarded as constant in precision allowed band, The test is exactly equal p test;If not, then according to new ε1~A relationship carries out equal p test again, iterates, until the value of p Meet until really waiting p experimental condition.
The preparation of the frozen soil sample uses the method for making sample in frozen soil mechanics test.
The low temperature triaxial apparatus is while having three axis of low temperature of Stress Control, strain controlling and multi-way contral mode Instrument.
Every level-one axial strain ε during the second step test1Value is not more than 0.05%, ensure that every level-one A's ' Variation is little.
Innovation of the invention is:
(1) the invention proposes a kind of method of the p such as high-precision frozen soil test, this method may be implemented high-precision etc. The vacancy that the not yet p such as development are tested in frozen soil has been filled up in p test.
(2) present invention has been included in body strain factor when correcting specimen cross sectional area.
(3) present invention is when correcting specimen cross sectional area, using last axial strain ε1With the pass of cross-sectional area A System cannot consider the difficulty of bulk strain to be modified when avoiding current load.
(4) present invention is the precision of p test such as to control by being similar to the method for iteration, and the area of each iteration is repaired Last body strain factor is just all being contained, is tending to result constantly accurately, i.e., arbitrary accuracy is being obtained by iteration several times Equal p test result.
(5) the principle of the present invention and step can be applied to the frozen soil mechanics examination of other any straight line stress paths It tests, the frozen soil mechanics experimental study of complicated stress environment may be implemented.
Detailed description of the invention:
Attached drawing 1 is present invention test process flow diagram flow chart;
Attached drawing 2 is the test value and theoretical value comparison diagram of the inferior p test of p=2MPa;
Specific embodiment:
Feature of present invention and other correlated characteristics are described in further detail below by way of specific test process, in order to The understanding of researcher of the same trade:
The present invention uses water content to make test specimen for 16.68% frozen Lanzhou loess to carry out the equal p test of frozen soil, has Steps are as follows for body:
1, the preparation of frozen soil sample
Soil is first configured to the scattered soil body of target water content, and keeps about 6h in the case where limiting evaporation conditions, makes moisture in soil In body uniformly, it is then layered die-filling, by the dry density of test requirements document by rammed earth densification, high 125mm, diameter 61.8mm is made Cylindrical specimens.Sample gang mould tool is put into togerther refrigeration case, the quick freezing in -30 DEG C of environment, freezes sample after about 48h Demoulding, then sample is placed in constant temperature 12h or more under test temperature and is tested.
2, test procedure
Step 1: frozen soil sample is put into low temperature triaxial apparatus when test, confining pressure is applied into target value and carries out isotonic consolidation, into The p such as row test;
Step 2: the cross-sectional area of every level-one frozen soil sample is calculated with axial strain to calculate every level-one frozen soil sample Cross-sectional area, thus by Δ p=Δ F/A+2 Δ σ3=0 determines the axle power increment △ F and corresponding confining pressure increment Delta σ of every level-one3 It is tested to carry out equal p, the axial strain increment ε of every level-one is taken during test1=0.05% guarantees the A ' variation of every level-one Less.
Step 3: calculating bulk strain ε using the test result in second stepv, then answered simultaneously with axial strain and volume Become and calculate the true cross-sectional area A of sample in second step test, and by p=(F/A+2 σ3)/3 calculate entire test process In mean stress p value.
3, test result is analyzed, correlation curve is drawn
The present invention is tested in the case where initial confining pressure is the stress level of 2MPa using low temperature triaxial apparatus.Fig. 2 is that test is answered The comparison of power path and theoretical stress path.
Shown by Fig. 2 almost the same in initial trial value and theoretical value.This is because in the initial stage of test, Since axial strain is smaller, the p test accuracy requirements such as second step of the invention just has sufficiently high precision to meet;It is answered when axially The test value in the path p begins to deviate from theoretical value when becoming larger etc., this illustrates that biggish change has occurred in the cross-sectional area of sample at this time Become, the area correction in second step, which is not able to satisfy, waits the requirement of p test accuracy, needs using the area correction in third step of the present invention Method setting test, the 4th step tested can just obtain satisfied test result.
Shown at lower p value (p=2MPa) by Fig. 2, the initial trial value and theoretical value of second step in the present invention Almost the same, only the test value with theoretical value in the path p are just begun to deviate from when axial strain is larger etc., this explanation is in lower p Under value, the p test accuracy requirements such as second step of the present invention just has sufficiently high precision to meet;When p value is larger, in the initial stage Test value and theoretical value begin to deviate, this explanation under higher p value, the correction of area in second step it is impossible to meet etc. The requirement of p test accuracy need to correct specimen cross sectional area setting test using third step of the present invention, and proceed to the 4th of test Step can just obtain satisfied test result.
Although the invention has been described by way of example and in terms of the preferred embodiments, but it is not for limiting the present invention, any this field Technical staff without departing from the spirit and scope of the present invention, may be by the methods and technical content of the disclosure above to this hair Bright technical solution makes possible variation and modification, therefore, anything that does not depart from the technical scheme of the invention, and according to the present invention Technical spirit any simple modifications, equivalents, and modifications to the above embodiments, belong to technical solution of the present invention Protection scope.

Claims (10)

1. p test methods such as a kind of high-precision frozen soil, it is characterised in that:
Step 1: frozen soil sample is put into low temperature triaxial apparatus when test, confining pressure is applied to the p tests such as test objective value carries out;
Equal p test passes through control mean stress increment Delta p=Δ (σ1+2σ3)=0 namely Δ σ1=-2 Δ σ3It realizes, and it is practical In loading procedure, confining pressure increment Delta σ3It can be directly controlled by confining pressure loading system, axial loading system can only control axle power increment Δ F, axial stress increment then need to be by Δ σ1=Δ F/A is calculated;With the increase of axial crushing deformation, frozen soil sample Cross-sectional area A can constantly increase, and accurately to calculate the Δ F that every level-one applies must just calculate sample when every level-one loads in advance Cross-sectional area A, cross-sectional area A are calculated according to bulk strain and axial strain;It thus can be according to Δ F=Δ σ1A=- 2Δσ3To calculate the axle power that every level-one need to apply;However bulk strain ε cannot be calculated when not completing by testingv, also can not just obtain To the A and Δ F when the load of every level-one, the present invention proposes a kind of method similar to iterative method to seek Δ F and A;
Step 2: according to ε1Much larger than εvThe fact, first only with axial strain come come the cross section that calculates every level-one frozen soil sample Product, thus by Δ p=Δ F/A+2 Δ σ3=0 determines the axle power increment △ F and corresponding confining pressure increment Delta σ of every level-one3Come carry out The p such as approximation test;
It should be by the axial strain increment ε of every level-one during test1It is little to obtain the sufficiently small A ' variation to guarantee every level-one, builds Discuss ε1Value is not more than 0.05%;
Step 3: calculating bulk strain ε using the test result in second stepv, then calculated the by axial strain and bulk strain The true cross-sectional area A of sample in the test of two steps, and by p=(F/A+2 σ3)/3 calculate averagely answering during entirely testing Power p;If the p value being calculated may be regarded as constant in precision allowed band, the test in second step can be used as precision Enough equal p tests;If the value of p changes greatly during the test cannot be considered as constant, can according to the test of second step at Fruit is with high-precision Function Fitting shaft to strain stress1With the relationship of specimen cross sectional area A;
Step 4: the ε according to obtained in third step1The A of every level-one is arranged in~A relationship, and the Δ F of every level-one, Δ σ is thus arranged3 Carry out equal p test;
True A and p is calculated after the test, if the variation of p value can be regarded as constant in precision allowed band, the examination Testing is exactly equal p test;If not, then according to new ε1~A relationship carries out equal p test again, iterates, until the value of p meets Until really waiting p experimental condition.
2. p test methods such as a kind of high-precision frozen soil according to claim 1, it is characterised in that: using with stress It controls, the low temperature triaxial apparatus of strain controlling and multi-way contral mode.
3. p test methods such as a kind of high-precision frozen soil according to claim 1, it is characterised in that: apply modified examination When sample cross-sectional area calculates axial stress, it is included in body strain.
4. p test methods such as a kind of high-precision frozen soil according to claim 1, it is characterised in that: horizontal in amendment sample When sectional area, using the axial strain ε of last time test1It is modified, avoids current with the relationship of cross-sectional area A The difficulty of body strain cannot be considered when load.
5. p test methods such as a kind of high-precision frozen soil according to claim 1, it is characterised in that: carrying out second step Test during every level-one axial strain increment ε1Value is not more than 0.05%, keeps the A ' variation of every level-one little, makes not yet It is included in resulting p value variation when body strain and less, to provide more accurate initial value, reduces iterative test number.
6. p test methods such as a kind of high-precision frozen soil according to claim 1, it is characterised in that: each sample is transversal The amendment of area all contains last body strain factor, and result is made constantly to tend to be accurate.
7. p test methods such as a kind of high-precision frozen soil according to claim 1, it is characterised in that: by successive ignition, High-precision equal p test may be implemented.
8. p test methods such as a kind of high-precision frozen soil according to claim 1, it is characterised in that: realize high-precision Equal p test is realized by a kind of method similar to iterative method.
9. p test methods such as a kind of high-precision frozen soil according to claim 1, it is characterised in that: this method is equally suitable Frozen soil mechanics for any straight line stress path is tested.
10. p test methods such as a kind of high-precision frozen soil according to claim 1, it is characterised in that: the principle of this method It can be applied to the high p such as soil that melt of required precision with test procedure to test.
CN201711336520.XA 2017-12-14 2017-12-14 A kind of p test methods such as high-precision frozen soil Pending CN109959563A (en)

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Publication number Priority date Publication date Assignee Title
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CN104913977A (en) * 2015-06-18 2015-09-16 兰州交通大学 Indoor frozen soil model pile static force loading experimental device and method
CN105300808A (en) * 2015-11-09 2016-02-03 重庆交通大学 Soil freezing and thawing cycle test device in triaxial test conditions and test method
CN106370596A (en) * 2016-08-19 2017-02-01 中国科学院寒区旱区环境与工程研究所 Device for measuring unfrozen water content of frozen soil on different stress paths

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN201780231U (en) * 2010-08-24 2011-03-30 清华大学 Equal strain incremental ratio test system
CN102331373A (en) * 2011-05-19 2012-01-25 中国科学院寒区旱区环境与工程研究所 Mobile temperature control constant stress loading testing device
CN104913977A (en) * 2015-06-18 2015-09-16 兰州交通大学 Indoor frozen soil model pile static force loading experimental device and method
CN105300808A (en) * 2015-11-09 2016-02-03 重庆交通大学 Soil freezing and thawing cycle test device in triaxial test conditions and test method
CN106370596A (en) * 2016-08-19 2017-02-01 中国科学院寒区旱区环境与工程研究所 Device for measuring unfrozen water content of frozen soil on different stress paths

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Application publication date: 20190702