CN101979776B - Method for measuring control dynamic shearing strain in fatigue dynamic tri-axial test - Google Patents
Method for measuring control dynamic shearing strain in fatigue dynamic tri-axial test Download PDFInfo
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- CN101979776B CN101979776B CN 201010520219 CN201010520219A CN101979776B CN 101979776 B CN101979776 B CN 101979776B CN 201010520219 CN201010520219 CN 201010520219 CN 201010520219 A CN201010520219 A CN 201010520219A CN 101979776 B CN101979776 B CN 101979776B
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Abstract
The invention discloses a method for measuring control dynamic shearing strain in a fatigue dynamic tri-axial test. The method comprises the following steps of: (1) charging a soil sample and draining and solidifying the soil sample; (2) closing a drain valve and applying vertical static stress and corresponding vertical dynamic stress in turn, wherein the cycle index of the vertical dynamic stress is more than or equal to 10,000; (3) recording the total vertical dynamic strain corresponding to each cycle index under the action of the vertical dynamic stress; (4) unloading the vertical dynamic stress so as to recover the structure of the soil sample; (5) correspondingly changing the magnitudes of the vertical static stress and the vertical dynamic stress, repeating the steps (2) to (4) and measuring and recording the total vertical dynamic strain corresponding to each cycle index under the actions of different vertical dynamic stress and vertical static stress; and (6) calculating a dynamic modulus and drawing relation curves between the dynamic modulus corresponding to different vertical dynamic stress and the cycle index under the same coordinate system so as to calculate the control dynamic shearing strain of the soil sample according to each curve. The method is simple and fast and has low cost.
Description
Technical field
The present invention relates to the soil test technique field of foundation soil kinematic behavior, relate in particular to the method that the moving triaxial test of a kind of fatigue is measured the moving shearing strain of control.
Background technology
The long-term kinetic stability evaluation method of railway bed mainly contains three kinds at present: critical dynamic stress method, effective vibration velocity method and moving shearing strain method.Wherein, the most frequently used is critical dynamic stress method and moving shearing strain method.
Subgrade bed soil can produce moving shearing strain under train dynamics, cyclic load effect.When moving shearing strain hour, the bedding dynamic stiffness increases with the increase of shake frequency; When moving shearing strain increased to above some values, dynamic stiffness reduced with the increase of shake frequency, and the moving shearing strain value of this boundary is called as the moving shearing strain of control.When the shearing strain of subgrade bed was moved shearing strain less than said control, the soil body produced strain hardening, and subgrade bed is stable under long-term dynamic load effect; When the shearing strain of subgrade bed during greater than the moving shearing strain of said control, the soil body produces strain softening, subgrade bed under long-term dynamic load effect with unstability.This shows that the moving shearing strain of control is the very important parameter of long-term kinetic stability of estimating railway bed.The moving shearing strain of the control of existing mensuration soil sample mainly is to adopt resonant column test.Yet because the testing expenses of resonant column test machine are higher, general soil mechanics laboratory and research institutions all do not have the resonant column test machine, and the problem that the resonant column test machine is difficult to popularize has restricted the foundation soil Research on Dynamic Characteristics to a great extent.And, adopt the resonant column test machine to measure the moving shearing strain of control, it is numerous to relate to parameter, and process is very complicated.Therefore, demand urgently providing a kind of simple efficiency test mensuration method that shearing strain is moved in control to overcome above-mentioned defective.
Summary of the invention
The technical matters that the present invention will solve is to provide the moving triaxial test of a kind of simple and effective fatigue to measure the method for the moving shearing strain of control; This method adopts dynamic triaxial apparatus to test the kinematic behavior of soil sample; Obtain the moving shearing strain of control of foundation soil; Greatly improve the test efficiency that railway bedding kinetic stability is estimated, and can effectively reduce testing expenses.
In order to solve the problems of the technologies described above, the invention provides the method that the moving triaxial test of a kind of fatigue is measured the moving shearing strain of control, it may further comprise the steps:
(1) in dynamic triaxial apparatus, installs soil sample, it is applied consolidation pressure and opens draining valve so that said soil sample discharging consolidation;
(2) close draining valve, apply vertical static stress σ
oAfter-applied corresponding vertical dynamic stress σ
d, said vertical dynamic stress σ
dCycle index more than or equal to 10000 times;
(3) be recorded in said vertical dynamic stress σ
dUnder the effect, the pairing vertical total dynamic strain ε of each cycle index
d
(4) the said vertical dynamic stress σ of removal
d, open draining valve, let soil sample leave standstill a period of time, so that the structure of soil sample is recovered fully;
(5) the vertical static stress σ of corresponding change
oWith vertical dynamic stress σ
dSize, repeating step (2)～(4) record and write down different vertical dynamic stress σ
dWith vertical static stress σ
oUnder the effect, the pairing vertical total dynamic strain ε of each cycle index
dWith
(6) calculate different vertical dynamic stress σ
dWith vertical static stress σ
oUnder the effect, the pairing modulus at rapid deformation E of different cycle indexes
d, under the same coordinate system, draw different vertical dynamic stress σ respectively
dCorresponding modulus at rapid deformation and the relation curve of cycle index, i.e. E
d～lgN curve is according to each E
dShearing strain γ is moved in the control of the said soil sample of～lgN curve calculation
Dc
The method that the moving triaxial test of fatigue of the present invention is measured the moving shearing strain of control adopts moving triaxial test instrument to carry out the tired dynamic test of foundation soil, obtains the moving shearing strain of control of foundation soil, can greatly improve the test efficiency that railway bedding kinetic stability is estimated.And moving triaxial test instrument popularization degree is high, can effectively reduce testing expenses.
Preferably, said step (6) specifically may further comprise the steps: (a) by formula
Calculate different vertical dynamic stress σ
dUnder the effect, the modulus at rapid deformation E that different cycle indexes are corresponding
d, wherein, μ is the Poisson ratio of soil sample; (b) in the same coordinate system, draw modulus at rapid deformation and the relation curve of cycle index, i.e. E under the different vertical dynamic stress effects respectively
d～lgN curve; (c) analyze each E
d～lgN curve is confirmed the modulus at rapid deformation when critical plastic yield takes place soil structures, then by formula
Calculate corresponding dynamic strain; (d) the vertical dynamic strain with soil sample is ε
D1=ε
d, the side direction dynamic strain is ε
D2=0.5 ε
D1, with
Be radius, with point
Be the center of circle, draw the strain Mohrcircle, read the moving shearing strain γ of corresponding maximum from Mohrcircle
Dmax, be the moving shearing strain γ of control
DcIt is few that this process relates to parameter, and computation process is simple, rapid and convenient.
Preferably, vertical static stress σ described in the said step (2)
oSize be corresponding said vertical dynamic stress σ
dHalf of size.
Preferably, the time of repose of the middle soil sample of said step (4) is greater than 1 hour, with the structure of abundant recovery soil sample.
Preferably, the dynamic triaxial apparatus in the said step (1) is a Stress Control formula dynamic triaxial apparatus.
Through following description and combine accompanying drawing, it is more clear that the present invention will become, and these accompanying drawings are used to explain embodiments of the invention.
Description of drawings
Fig. 1 measures the schematic flow sheet of an embodiment of the method for controlling moving shearing strain for the tired moving triaxial test of the present invention.
Embodiment
With reference now to accompanying drawing, describe embodiments of the invention, the similar elements label is represented similar elements in the accompanying drawing.As stated; The invention provides the moving triaxial test of a kind of simple and effective fatigue and measure the method for the moving shearing strain of control; The kinematic behavior that this method adopts dynamic triaxial apparatus to come test pattern; Obtain the moving shearing strain threshold value of volume of foundation soil, greatly improved the test efficiency that railway bedding kinetic stability is estimated, and can effectively reduce testing expenses.
To combine accompanying drawing to set forth the technical scheme of the embodiment of the invention in detail below.As shown in Figure 1, the method that the moving triaxial test of the fatigue of present embodiment is measured the moving shearing strain of control may further comprise the steps:
Step S101: in dynamic triaxial apparatus, install soil sample, it is applied consolidation pressure and opens draining valve so that said soil sample discharging consolidation.Concrete, the working specification of (SL-237-032-1999) stipulating according to " dynamic triaxial test " installs soil sample in dynamic triaxial apparatus.Said dynamic triaxial apparatus is preferably Stress Control formula dynamic triaxial apparatus.
Step S102: close draining valve, apply vertical static stress σ
oAfter-applied corresponding vertical dynamic stress σ
d, said vertical dynamic stress σ
dCycle index more than or equal to 10000 times.Said vertical static stress σ
oSize be corresponding said vertical dynamic stress σ
dHalf of size.
Step S103: be recorded in said vertical dynamic stress σ
dUnder the effect, the pairing vertical total dynamic strain ε of each cycle index
d
Step S104: the said vertical dynamic stress σ of removal
d, open draining valve, let soil sample leave standstill a period of time, so that the structure of soil sample is recovered fully.The time of repose of said soil sample was greater than 1 hour, and the said vertical dynamic stress that applies is big more, and said time of repose is long more.
Step S105: the vertical static stress σ of corresponding change
oWith vertical dynamic stress σ
dSize, repeating step (2)～(4) record and write down different vertical dynamic stress σ
dWith vertical static stress σ
oUnder the effect, the pairing vertical total dynamic strain ε of each cycle index
d
Step S106: calculate different vertical dynamic stress σ
dWith vertical static stress σ
oUnder the effect, the pairing modulus at rapid deformation E of different cycle indexes
d, under the same coordinate system, draw different vertical dynamic stress σ respectively
dCorresponding modulus at rapid deformation and the relation curve of cycle index, i.e. E
d～lgN curve is according to each E
dShearing strain γ is moved in the control of the said soil sample of～lgN curve calculation
Dc
Further, this step comprises:
(a) by formula
Calculate different vertical dynamic stress σ
dUnder the effect, the modulus at rapid deformation E that different cycle indexes are corresponding
d, wherein, μ is the Poisson ratio of soil sample.For example, for soft moulding red clay, μ=0.38; For the plasticity red clay, μ=0.35; For hard plasticity red clay, μ=0.32.
(b) in the same coordinate system, draw modulus at rapid deformation and the relation curve of cycle index, i.e. E under the different vertical dynamic stress effects respectively
d～lgN curve;
(c) analyze each E
d～lgN curve is confirmed the modulus at rapid deformation when critical plastic yield takes place soil structures, then by formula
Calculate corresponding dynamic strain;
(d) the vertical dynamic strain with soil sample is ε
D1=ε
d, the side direction dynamic strain is ε
D2=0.5 ε
D1, with
Be radius, with point
Be the center of circle, draw the strain Mohrcircle, read the moving shearing strain γ of corresponding maximum from Mohrcircle
Dmax, be the moving shearing strain γ of control
DcIt is few that this process relates to parameter, and computation process is simple, rapid and convenient.
The moving shearing strain γ of control when using method of the present invention to measure the oral examination of Wuhan-Guangzhou passenger-dedicated line spring to test the worker and put the different consolidation ratio of red clay
Dc, the result sees the following form, and has wherein comprised under the different tests condition, different water cut is than the moving shearing strain threshold γ of the volume of red clay
Tv
The method that the moving triaxial test of fatigue of the present invention is measured the moving shearing strain of control adopts moving triaxial test instrument to carry out the tired dynamic test of foundation soil, obtains the moving shearing strain of control of foundation soil, can greatly improve the test efficiency that railway bedding kinetic stability is estimated.And advantage such as it is more universal that this method also has test apparatus, and testing expenses are lower, test is reliable has good popularizing application prospect.
Claims (3)
1. the moving triaxial test of fatigue is measured the method that shearing strain is moved in control, it is characterized in that, may further comprise the steps:
(1) in dynamic triaxial apparatus, installs soil sample, it is applied consolidation pressure and opens draining valve so that said soil sample discharging consolidation;
(2) close draining valve, apply vertical static stress σ
oAfter-applied corresponding vertical dynamic stress σ
d, said vertical dynamic stress σ
dCycle index more than or equal to 10000 times;
(3) be recorded in said vertical dynamic stress σ
dUnder the effect, the pairing vertical total dynamic strain ε of each cycle index
d
(4) the said vertical dynamic stress σ of removal
d, open draining valve, let soil sample leave standstill a period of time, so that the structure of soil sample is recovered fully;
(5) the vertical static stress σ of corresponding change
oWith vertical dynamic stress σ
dSize, repeating step (2)～(4) record and write down different vertical dynamic stress σ
dWith vertical static stress σ
oUnder the effect, the pairing vertical total dynamic strain ε of each cycle index
dWith
(6) calculate different vertical dynamic stress σ
dWith vertical static stress σ
oUnder the effect, the pairing modulus at rapid deformation E of different cycle indexes
d, under the same coordinate system, draw different vertical dynamic stress σ respectively
dCorresponding modulus at rapid deformation and the relation curve of cycle index, i.e. E
d～lgN curve, wherein, N representes cycle index, according to each E
dShearing strain γ is moved in the control of the said soil sample of～lgN curve calculation
Dc
Said step (6) specifically may further comprise the steps:
(a) by formula
Calculate different vertical dynamic stress σ
dUnder the effect, the modulus at rapid deformation E that different cycle indexes are corresponding
d, wherein, μ is the Poisson ratio of soil sample;
(b) in the same coordinate system, draw modulus at rapid deformation and the relation curve of cycle index, i.e. E under the different vertical dynamic stress effects respectively
d～lgN curve;
(c) analyze each E
d～lgN curve is confirmed the modulus at rapid deformation when critical plastic yield takes place soil structures, then by formula
Calculate corresponding dynamic strain;
(d) the vertical dynamic strain with soil sample is ε
D1=ε
d, the side direction dynamic strain is ε
D2=0.5 ε
D1, with
Be radius, with point
Be the center of circle, draw the strain Mohrcircle, read the moving shearing strain γ of corresponding maximum from Mohrcircle
Dmax, be the moving shearing strain γ of control
Dc
2. method according to claim 1 is characterized in that, vertical static stress σ described in the said step (2)
oSize be corresponding said vertical dynamic stress σ
dHalf of size.
3. method according to claim 1 and 2 is characterized in that, the time of repose of soil sample was greater than 1 hour in the said step (4).
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Citations (3)
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|---|---|---|---|---|
| US4326409A (en) * | 1980-05-19 | 1982-04-27 | Hughes John M O | Situ bore hole test probe |
| CN85105332B (en) * | 1985-07-10 | 1988-06-01 | 武汉工学院 | Multipurpose test instrument for soil strength |
| CN101705678A (en) * | 2009-11-04 | 2010-05-12 | 广东永基建筑基础有限公司 | Cone penetration method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001147188A (en) * | 1999-11-19 | 2001-05-29 | Takenaka Komuten Co Ltd | Method of finding shearing rigidity lowering rate from fl value |
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2010
- 2010-10-26 CN CN 201010520219 patent/CN101979776B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4326409A (en) * | 1980-05-19 | 1982-04-27 | Hughes John M O | Situ bore hole test probe |
| CN85105332B (en) * | 1985-07-10 | 1988-06-01 | 武汉工学院 | Multipurpose test instrument for soil strength |
| CN101705678A (en) * | 2009-11-04 | 2010-05-12 | 广东永基建筑基础有限公司 | Cone penetration method |
Non-Patent Citations (2)
| Title |
|---|
| JP特开2001-147188A 2001.05.29 |
| 刘晓红，杨果林，方薇.武广客运专线路堑红粘土临界动应力疲劳试验研究.《湘潭大学自然科学学报》.2010,(第2期),57-62. * |
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