CN102866071A - Building method of ice layer dynamic settlement prediction model - Google Patents
Building method of ice layer dynamic settlement prediction model Download PDFInfo
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- CN102866071A CN102866071A CN2012104068447A CN201210406844A CN102866071A CN 102866071 A CN102866071 A CN 102866071A CN 2012104068447 A CN2012104068447 A CN 2012104068447A CN 201210406844 A CN201210406844 A CN 201210406844A CN 102866071 A CN102866071 A CN 102866071A
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Abstract
The invention provides a building method of an ice layer dynamic settlement prediction model. The method aims at fatigue failure effect of vibration of running back and forth of trains on the Chinese qinghai-tibet railway on the ice layer containing soil below permafrost subgrade, gives consideration to influence of various factors of minus temperature, amplitude, frequency, vibration duration and the like on dynamic residual deformation of the ice layer and is based on low-temperature dynamic triaxial tests, and the dynamic settlement prediction model of ice under long-term effect of rail transit power is built. The building method of the ice layer dynamic settlement prediction model is important for studying reasonable prediction of settlement amount generated by ice residual deformation under the effect of long-term power load and accumulates basic test achievements for studying of permafrost dynamics.
Description
Technical field: the present invention sets up the sunken forecast model that shakes of ice sheet under the long-term dynamic action of train load, is a pith in Geotechnical Engineering field.
Background technology:
Shaking that (shake) fall into is the residual deformation that is caused soil layer by dynamic load function, and as one of power foundation shock hazards, in the sixties in last century, Chinese scholars has mainly been carried out correlative study take weak soil such as saturated clay, mud as object.Because the existence of ice phase, frozen soil has flowability usually under dead load, and the rheological problem of frozen soil will be more outstanding under the long-term dynamic loading.At present, about the research work of frozen soil power Rheological Problems seldom, and more have no bibliographical information for the achievement in research of frozen soil place roadbed train driving kinetic stability.Yet, the round dynamic load of travelling of train is on the existing example of the impact of frozen soil place subgrade deformation, contain such as Qinghai-Tibet Railway 134km high temperature high ice content highway section and to contain in a large number native ice sheet, train driving is open to traffic and part frozen soil section subgrade settlement and cracking phenomena just occurs less than two months, thereby causes that railway interests pays much attention to; 1962, the accident that subgrade settlement 1.4m causes locomotive to slide down in 5 hours once occured in tooth timberline tide crow section 8 km places; 1.5 m that once sink also occured in tooth timberline K197 place, the accident that forces passenger train to stop 4 hours.Given this, the present invention's fatigure failure effect that directly round vibration of travelling produces containing native ice sheet under frozen earth roadbed for the Qinghai-Tibet railway in China train, consider that ice sheet power residual deformation is subjected to subzero temperature, amplitude, frequency, the various factors such as when vibration is held, based on the moving triaxial test of low temperature, set up the sunken forecast model that shakes of icing under a kind of track traffic power long term.This research is significant for the settling amount that is produced by the ice residual deformation under the long-term dynamic load function of reasonable prediction, and is permafrost dynamics research accumulation basic test achievement.
Summary of the invention:
Test resulting icicle body overstrain and number of loading according to indoor dynamic
NRelation calculate the laboratory experiment method of permanent strain, have intuitive and reliable, calculate the outstanding advantages such as simple, can be used for containing under the Qinghai-Tibet Railway in Permafrost roadbed under the periodicity load long term such as train shaking of Tu Bingcengchu and fall into and predict.
The present invention adopts the laboratory experiment method to set up the sunken forecast model that shakes of ice.The fast fetching ice sample is mounted to the low temperature three-axis tester during test, puts isotonic consolidation 10 min in the three axle low-temperature pressure chambeies into, tests.Axial dynamic load is sinusoidal wave for pressure-die mould, is determined by maximum stress, minimum stress and frequency.In order to simulate better traffic loading to the impact of strain rate, with maximum stress as variable; certain one-level load of getting the kinetic parameter test of ice is the loading standard; only add the amplitude cycling cycling vibration load such as one-level until termination criteria, studies under the long-term dynamic load function ice deformation characteristic and shakes sunken forecast model.The controlling test condition sees Table 1, and totally 11 soil samples are got confined pressure
=0.3MPa considers the deformation characteristic experiment under three kinds of different subzero temperatures-0.5 C ,-1.0 C ,-1.5 C, three kinds of different frequency 1 Hz, 2 Hz, 3 Hz, three kinds of different dynamic stress amplitude 0.166 MPa, 0.333 MPa, 0.499 MPa.Get axial dynamic strain and the termination criteria of largest loop shake frequency N=20000 for testing of 10 %.
Table 1 ice shake fall into experiment control condition and fitting parameter (
=0.3MPa)
Annotate:
Be axial circulation dynamic stress amplitude,
=(
-
)/2
The definition of the power overstrain of under long-term dynamic load function, icing
Dynamic residual strain is that the dynamic stress effect stops the residual strain value of rear ice test specimen, then is the ratio of sample elemental height before the difference in height of sample before and after the dynamic stress effect and the dynamic stress effect in the moving triaxial test of the problem that falls into is shaken in research.Usually get the axial circulation dynamic stress width of cloth
The time strain be overstrain, namely
KThe point strain is the dynamic residual strain of definition
(see figure 1).
Ice deformation relation is complicated, and is subjected to the various factors such as subzero temperature, frequency, dynamic stress amplitude, and test figure is analyzed with MATLAB7.0 and obtained dynamic residual strain and shake frequency relation curve shown in Fig. 2 ~ 4.The dynamic residual strain that can find out generally ice from figure increases with the increase of shake frequency, the overstrain value begins to increase fast, the dynamic residual strain rate of rise of high shake frequency level (tangent slope of curve point) is significantly less than the regularity cognitions such as dynamic residual strain speed of low shake frequency level, and analysis can think that dynamic load has an initial densification process to test specimen when just having begun to load behind the isotonic consolidation.
Based on shop experiment, obtain the axial overstrain of icicle body under the different circulation dynamic stress effect shake frequency N effect
, carry out regretional analysis with MATLAB7.0 and set up the shake sunken forecast model of ice under the Long-term Vibration load action:
In the formula:
Be axial overstrain,
Be circulation dynamic stress effect shake frequency,
B, cBe the shake sunken parameter relevant with subzero temperature, the dynamic stress width of cloth, confined pressure and shake frequency.Known by the Creep of Frozen Soil theory, the 1st expression subordinate phase (viscoplastic flow) creep in the formula (1), the 2nd expression primary creep, creep namely decays.So, parameter
B, cClear and definite physical significance is also arranged.Parameter
bBe average creep rate of the second creep stage, it represents the ultimate value of the minimized creep rate that frozen soil produces under certain external load effect; Parameter
cBe the creep attenuation coefficient.
Shaking of gained fallen into curve and seen Fig. 2 with matched curve under various test conditions, and as can be seen from the figure empirical curve and matched curve are well identical, and fitting precision is high.Fitting parameter sees Table 1, and ice deformation characteristic and influence factor labor are as follows under the long-term dynamic load function.
Subzero temperature
Under identical vibration frequency, confined pressure, dynamic stress amplitude condition, the sunken curve that shakes of different temperatures is seen Fig. 2.As seen from the figure, during ice subzero temperature-0.5 ℃, overstrain gathers way obviously faster than-1.5 ℃, shows that temperature is higher, and the ice fatigue resistance is lower, and anti-dynamic load performance is poorer.
The sunken prediction model parameters that shakes of different temperatures is seen Fig. 3, table 1.As seen from the figure, viscoplastic flow creep rate b and creep attenuation coefficient c reduce with the reduction of temperature.
The dynamic stress width of cloth
Under identical vibration frequency, confined pressure and subzero temperature condition, shaking under the different dynamic stress spoke parts fallen into curve and seen Fig. 4.As seen from the figure, the dynamic stress amplitude is larger, and the overstrain of ice gathers way faster, and the dynamic stress amplitude is extremely remarkable on the residual strain impact.In addition, the overstrain increment when dynamic stress width of cloth increment is identical under three kinds of subzero temperatures of contrast from figure can find out that also in the identical shake frequency situation, ice temperature is higher by (0.5
0C) overstrain is than Low-temperature Ice (1.5
0C) obviously much larger, high temperature ice is more responsive to the increase of the dynamic stress width of cloth.The main cause of this phenomenon is that the dynamic stress width of cloth is larger, and vibrational energy is larger, and the distortion that frozen soil produces is just larger; Because vibrational energy is converted into heat energy, and the ice crystal body heat is melted, i.e. the growth of micro-crack reduces the contiguity of intergranular again, causes the ice structure reduction.
Shaking under the different stress ratio conditions fallen into prediction model parameters and seen Fig. 5, table 1.As seen from the figure, viscoplastic flow creep rate
bWith the creep attenuation coefficient
cHour increase with the increase of circulation dynamic stress amplitude at pulsating stress, when cyclic stress amplitude is larger (
=0.5567), viscoplastic flow creep rate
bIncrease comparatively fast, creep attenuation coefficient c slightly reduces.
Frequency
Under identical dynamic stress amplitude, confined pressure and subzero temperature condition, the sunken curve that shakes of different frequency is seen Fig. 6.As seen, overstrain gathers way and comparatively fast (sees HBY-14) during low frequency; The overstrain increase was the slowest when frequency was 3Hz.In addition, also can find out from figure, obviously much larger when overstrain is than high frequency during low frequency in the identical shake frequency situation, low frequency more easily makes ice sample generation overstrain.Frequency has reflected time effect to the impact of overstrain.The intensity time of ice can decay, and like this, loading speed just has a great impact the intensity of ice.Frequency is less, and the speed that loads and unload is all slow, and the various intensity of ice are also less, and rigidity is also poor, and dynamic modulus of elasticity is just little, and distortion is just large.In the time of in loading frequency is in high-frequency range, the speed that loads and unload is all larger, and above-mentioned time effect is all not obvious, so the value of residual deformation changes not quite.
Shaking under the different frequency condition fallen into prediction model parameters and seen Fig. 7, table 1, as seen from the figure, and the viscoplastic flow creep rate
bIncrease with circulation dynamic stress frequency increases, the creep attenuation coefficient
cIncrease with frequency reduces.
Based on above-mentioned test findings, be not difficult to find out the viscoplastic flow creep rate of ice
b, the creep attenuation coefficient
cAlso should be subjected to the combined effect of the factors such as subzero temperature, stress ratio, frequency, can be expressed as the function between each factor.Accordingly, to above test result, adopt Multiple Regression Analysis Method, can obtain parameter
b,
cWith each influence factor Relations Among suc as formula shown in (2), the formula (3).
In the formula,
Be respectively the viscoplastic flow creep rate of ice
bSubzero temperature, stress ratio, frequency correction factor, calculated by following formula:
Be respectively the creep attenuation coefficient of ice
cSubzero temperature, stress ratio, frequency correction factor, calculated by following formula:
Calculate the viscoplastic flow creep rate of ice according to above given fitting formula
B,The creep attenuation coefficient
cContrast sees Table 2 between regressand value and the trial value.
Shaking of table 2 ice falls into model parameter experiment value and regressand value contrast
Remarks:
=0.3MPa; Experiment value is the parameter according to test data fitting; Regressand value is to determine by formula (2), (3).
Description of drawings:
The definition of the axial dynamic residual strain of Fig. 1
Ice dynamic residual strain and shake frequency Relations Among curve under Fig. 2 condition of different temperatures
Fig. 3 subzero temperature falls into the impact of prediction model parameters on shaking
Ice dynamic residual strain and shake frequency Relations Among curve under the different stress ratio conditions of Fig. 4
Fig. 5 stress ratio falls into the impact of prediction model parameters on shaking
Frozen soil dynamic residual strain under Fig. 6 different frequency condition and shake frequency Relations Among curve
Fig. 7 frequency falls into the impact of prediction model parameters on shaking
Embodiment:
Three shaft material testing machines of the present invention are the MTS-810 type oscillation three axis Material Testing Machine that American MTS company produces, be furnished with automatic numerical control and data acquisition system (DAS), confined pressure scope 0 ~ 20MPa, the subzero temperature scope is normal temperature ~-30 ℃, frequency range is 0 ~ 50Hz, the maximum axial load is 250kN, and maximum axial displacement is 50mm.
Ice sample that the present invention adopts is for icing test specimen according to Standard for test methods of earthworks (GB/T50123-1999), Code for measurement method of dynamic properties of subsoil (GB/T 50269-1997) preparation engineering with artificial freezing method respectively.For guaranteeing the comparability of test findings, adopt standard method to prepare in batches test specimen, the ice sample of selecting is that the artificial isotropy Polycrystalline Ice of particle diameter＜2 mm is made cylindric ice sample, diameter 61.8 mm, length 125 mm, average density is 0.87 g.cm-3.Ice sample is put into constant temperature oven with the rubber membrane sealing, and more than constant temperature 48 h under the given test temperature, temperature error is ± 0.1 ℃.
Claims (5)
1. an ice sheet shakes and falls into the method for building up of forecast model, it is characterized in that:
The first step, axial dynamic load is sinusoidal wave for pressure-die mould, is determined by maximum stress, minimum stress and frequency;
In order to simulate better traffic loading to the impact of strain rate, with maximum stress as variable; certain one-level load of getting the kinetic parameter test of ice is the loading standard; only add the amplitude cycling cycling vibration load such as one-level until termination criteria, studies under the long-term dynamic load function ice deformation characteristic and shakes sunken forecast model;
Totally 11 soil samples are got confined pressure
=0.3MPa considers the deformation characteristic experiment under three kinds of different subzero temperatures-0.5 C ,-1.0 C ,-1.5 C, three kinds of different frequency 1 Hz, 2 Hz, 3 Hz, three kinds of different dynamic stress amplitude 0.166 MPa, 0.333 MPa, 0.499 MPa; Get axial dynamic strain and the termination criteria of largest loop shake frequency N=20000 for testing of 10 %;
Second step based on shop experiment, obtains the axial overstrain of icicle body under the different circulation dynamic stress effect shake frequency N effect
, carry out regretional analysis with MATLAB7.0 and set up the shake sunken forecast model of ice under the Long-term Vibration load action:
In the formula:
Be axial overstrain,
Be circulation dynamic stress effect shake frequency,
B, cBe the shake sunken parameter relevant with subzero temperature, the dynamic stress width of cloth, confined pressure and shake frequency;
Known by the Creep of Frozen Soil theory, the 1st expression subordinate phase (viscoplastic flow) creep in the formula (1), the 2nd expression primary creep, creep namely decays;
So, parameter
B, cClear and definite physical significance is also arranged;
Parameter
bBe average creep rate of the second creep stage, it represents the ultimate value of the minimized creep rate that frozen soil produces under certain external load effect; Parameter
cBe the creep attenuation coefficient;
In the 3rd step, obtain under identical vibration frequency, confined pressure, dynamic stress amplitude condition the sunken curve that shakes of different temperatures, the sunken prediction model parameters that shakes of different temperatures according to experimental result
b,
cAnd under identical vibration frequency, confined pressure and subzero temperature condition, the sunken curve that shakes under the different dynamic stress spoke parts, the sunken prediction model parameters that shakes under the different stress ratio conditions
b,
cAnd under identical dynamic stress amplitude, confined pressure and subzero temperature condition, the sunken curve that shakes of different frequency, the sunken prediction model parameters that shakes under the different frequency condition
b,
c
The 4th step, to above test result, adopt Multiple Regression Analysis Method, can obtain parameter
b,
cWith each influence factor Relations Among suc as formula shown in (2), the formula (3);
In the formula,
Be respectively the viscoplastic flow creep rate of ice
bSubzero temperature, stress ratio, frequency correction factor, calculated by following formula:
Be respectively the creep attenuation coefficient of ice
cSubzero temperature, stress ratio, frequency correction factor, calculated by following formula
2. method for establishing model according to claim 1, it is characterized in that: the low temperature three-axis tester is the MTS-810 type oscillation three axis Material Testing Machine that American MTS company produces, be furnished with automatic numerical control and data acquisition system (DAS), confined pressure scope 0 ~ 20MPa, the subzero temperature scope is normal temperature ~-30 ℃, frequency range is 0 ~ 50Hz, and the maximum axial load is 250kN, and maximum axial displacement is 50mm.
3. described method for establishing model according to claim 1-2 is characterized in that: the ice sample that adopts for respectively according to Standard for test methods of earthworks (GB/T50123-1999), Code for measurement method of dynamic properties of subsoil (GB/T 50269-1997) preparation engineering with artificial freezing method ice test specimen.
4. described method for establishing model according to claim 1-3, it is characterized in that: adopt standard method to prepare in batches described ice sample, the ice sample of selecting is that the artificial isotropy Polycrystalline Ice of particle diameter＜2 mm is made cylindric ice sample, diameter 61.8 mm, length 125 mm, average density is 0.87 g.cm-3.
5. described method for establishing model according to claim 1-4 is characterized in that: described ice sample is put into constant temperature oven with the rubber membrane sealing, and more than constant temperature 48 h under the given test temperature, temperature error is ± 0.1 ℃.
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| CN106568661A (en) * | 2016-11-07 | 2017-04-19 | 株洲时代新材料科技股份有限公司 | Testing acquisition method of epsilon-N fatigue curve under rubber material typical bearing working conditions |
| CN107340110A (en) * | 2017-06-26 | 2017-11-10 | 天津航天瑞莱科技有限公司 | A kind of vibration integrated pilot system of accumulated ice sleet |
| CN114399113A (en) * | 2022-01-14 | 2022-04-26 | 成都秦川物联网科技股份有限公司 | Natural gas pipe network management method and system |
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Cited By (4)
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| CN106568661A (en) * | 2016-11-07 | 2017-04-19 | 株洲时代新材料科技股份有限公司 | Testing acquisition method of epsilon-N fatigue curve under rubber material typical bearing working conditions |
| CN106568661B (en) * | 2016-11-07 | 2019-06-21 | 株洲时代新材料科技股份有限公司 | A kind of rubber material typical case carries ε~N curve of fatigue under operating condition and tests acquisition methods |
| CN107340110A (en) * | 2017-06-26 | 2017-11-10 | 天津航天瑞莱科技有限公司 | A kind of vibration integrated pilot system of accumulated ice sleet |
| CN114399113A (en) * | 2022-01-14 | 2022-04-26 | 成都秦川物联网科技股份有限公司 | Natural gas pipe network management method and system |
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Application publication date: 20130109 |