期刊文献+
共找到21篇文章
< 1 2 >
每页显示 20 50 100
Cyclic shear behavior of en-echelon joints under constant normal stiffness conditions 被引量:1
1
作者 Bin Wang Yujing Jiang +3 位作者 Qiangyong Zhang Hongbin Chen Richeng Liu Yuanchao Zhang 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第9期3419-3436,共18页
To reveal the mechanism of shear failure of en-echelon joints under cyclic loading,such as during earthquakes,we conducted a series of cyclic shear tests of en-echelon joints under constant normal stiffness(CNS)condit... To reveal the mechanism of shear failure of en-echelon joints under cyclic loading,such as during earthquakes,we conducted a series of cyclic shear tests of en-echelon joints under constant normal stiffness(CNS)conditions.We analyzed the evolution of shear stress,normal stress,stress path,dilatancy characteristics,and friction coefficient and revealed the failure mechanisms of en-echelon joints at different angles.The results show that the cyclic shear behavior of the en-echelon joints is closely related to the joint angle,with the shear strength at a positive angle exceeding that at a negative angle during shear cycles.As the number of cycles increases,the shear strength decreases rapidly,and the difference between the varying angles gradually decreases.Dilation occurs in the early shear cycles(1 and 2),while contraction is the main feature in later cycles(310).The friction coefficient decreases with the number of cycles and exhibits a more significant sensitivity to joint angles than shear cycles.The joint angle determines the asperities on the rupture surfaces and the block size,and thus determines the subsequent shear failure mode(block crushing and asperity degradation).At positive angles,block size is more greater and asperities on the rupture surface are smaller than at nonpositive angles.Therefore,the cyclic shear behavior is controlled by block crushing at positive angles and asperity degradation at negative angles. 展开更多
关键词 En-echelon joint cyclic shear tests Shear stress Normal displacement Constant normal stiffness(CNS)
下载PDF
Experimental investigation on shear strength deterioration at the interface between different rock types under cyclic loading
2
作者 Qiong Wu Zhiqi Liu +6 位作者 Huiming Tang Liangqing Wang Xiaoxue Huo Zhen Cui Shiyu Li Bo Zhang Zhiwei Lin 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第8期3063-3079,共17页
The shear strength deterioration of bedding planes between different rock types induced by cyclic loading is vital to reasonably evaluate the stability of soft and hard interbedded bedding rock slopes under earthquake... The shear strength deterioration of bedding planes between different rock types induced by cyclic loading is vital to reasonably evaluate the stability of soft and hard interbedded bedding rock slopes under earthquake;however,rare work has been devoted to this subject due to lack of attention.In this study,experimental investigations on shear strength weakening of discontinuities with different joint wall material(DDJM)under cyclic loading were conducted by taking the interface between siltstone and mudstone in the Shaba slope of Yunnan Province,China as research objects.A total of 99 pairs of similar material samples of DDJM(81 pairs)and discontinuities with identical joint wall material(DIJM)(18 pairs)were fabricated by inserting plates,engraved with typical surface morphology obtained by performing three-dimensional laser scanning on natural DDJMs sampled from field,into mold boxes.Cyclic shear tests were conducted on these samples to study their shear strength changes with the cyclic number considering the effects of normal stress,joint surface morphology,shear displacement amplitude and shear rate.The results indicate that the shear stress vs.shear displacement curves under each shear cycle and the peak shear strength vs.cyclic number curves of the studied DDJMs are between those of DIJMs with siltstone and mudstone,while closer to those of DIJMs with mudstone.The peak shear strengths of DDJMs exhibit an initial rapid decline followed by a gradual decrease with the cyclic number and the decrease rate varies from 6%to 55.9%for samples with varied surface morphology under different testing conditions.The normal stress,joint surface morphology,shear displacement amplitude and shear rate collectively influence the shear strength deterioration of DDJM under cyclic shear loading,with the degree of influence being greater for larger normal stress,rougher surface morphology,larger shear displacement amplitude and faster shear rate. 展开更多
关键词 Discontinuities with different joint wall material(DDJM) Discontinuities with identical joint wall material(DIJM) cyclic shear test Shear strength deterioration Joint surface morphology Shear displacement amplitude Shear rate Normal stress
下载PDF
Numerical analysis of loess and weak intercalated layer failure behavior under direct shearing and cyclic loading 被引量:3
3
作者 ZHANG Ze-lin WANG Tao 《Journal of Mountain Science》 SCIE CSCD 2020年第11期2796-2815,共20页
The mechanical behavior of the joints inside a loess layer is greatly important in weak intercalation studies owing to its involvement in a wide range of landslides in the loess region in China.The shear behavior of t... The mechanical behavior of the joints inside a loess layer is greatly important in weak intercalation studies owing to its involvement in a wide range of landslides in the loess region in China.The shear behavior of the joints in the loess stratum during direct shear and cyclic loadings was investigated using the PFC2D discrete element software.Loess mudstone and mudstone with weak intercalated layer materials were subjected to direct testing,and cyclic shear tests were conducted with consideration to the influence of normal stress and shear velocity.The macroscopic properties and damage patterns were obtained for six numerical configurations;namely,loess-weathered mudstone with 0°,10°,and-10°joints and weathered mudstone with 0°,10°,and-10°weak intercalated layers.The numerical test results revealed that,in the direct shear tests,the shear stress and shear displacement of the samples increased with the normal stress.In the cyclic shear tests with a total cycle number N=20,the shear stress-shear strain curve of the six different configurations exhibited a hysteresis loop.The numerical tests also revealed that,under cyclic shear,the normal stress and shear velocity affected the shear strength.The degree of damage increased as the shear velocity decreased from 0.1 mm/s to 0.005 mm/s for all six numerical configurations.Compared with the damage pattern of the direct shear tests,the damage of the cyclic shear tests mainly comprised shear cracks and fractures,some shaking consolidation settlement and fewer shear strain occurred around the joints.In the direct shear tests,more compression cracks and fractures occurred in the samples.The damage mainly developed along the joints,and shearing-off damage occurred.The results obtained by this study further elucidate the failure mechanism and microscopic damage response of the joints in the loess stratum in Northwest China. 展开更多
关键词 LOESS MUDSTONE Weak intercalated layer Direct shear test cyclic shear test PFC2D
下载PDF
Experimental Studies on Cyclic Shear Behavior of Steel-Clay Interface Under Constant Normal Load
4
作者 YU Shi-wen WANG Jie +1 位作者 LIU Jun-wei WANG Teng 《China Ocean Engineering》 SCIE EI CSCD 2023年第3期519-524,共6页
The degradation of the shear stress between pile-clay interface caused by undrained cyclic jacking affects the jacking force.A series of large displacement monotonic shear,cyclic shear and post-cyclic monotonic steel ... The degradation of the shear stress between pile-clay interface caused by undrained cyclic jacking affects the jacking force.A series of large displacement monotonic shear,cyclic shear and post-cyclic monotonic steel plate-clay interface shear te sts were performed under the constant normal load(CNL)condition to inve stigate the effects of normal stre ss,cyclic amplitude,and number of cycles on a steel plate-clay interface using the GDS multi-function interface shear tester.Based on the experimental results,in monotonic shear tests,change of shear stress took place in the specimen,the shear stress rapidly reached the peak value at shear displacement of 1 mm,and then abruptly decreased to the residual value.In cyclic shear te sts,accumulated displacement was a better parameter to describe the soil degradation characteristics,and the degradation degree of shear stress became greater with the increasing of normal stress and accumulated displacement.Shear stress in post-cyclic monotonic shear tests did not generate a peak value and was lower than that in monotonic shear tests under the same normal stress.The soil was completely disturbed and reached the residual strength when the cumulative displacement approached 6 m.An empirical equation to evaluate shear stress degradation mechanism was formulated and the procedure of parameter identification was presented. 展开更多
关键词 cyclic shear steel-clay interface constant normal load cumulative displacement residual strength
下载PDF
Assessment of liquefaction potential based on shear wave velocity:Strain energy approach
5
作者 Mohammad Hassan Baziar Mahdi Alibolandi 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第9期3733-3745,共13页
Liquefaction assessment based on strain energy is significantly superior to conventional stress-based methods.The main purpose of the present study is to investigate the correlation between shear wave velocity and str... Liquefaction assessment based on strain energy is significantly superior to conventional stress-based methods.The main purpose of the present study is to investigate the correlation between shear wave velocity and strain energy capacity of silty sands.The dissipated energy until liquefaction occurs was calculated by analyzing the results of three series of comprehensive cyclic direct simple shear and triaxial tests on Ottawa F65,Nevada,and Firoozkuh sands with varying silt content by weight and relative densities.Additionally,the shear wave velocity of each series was obtained using bender element or resonant column tests.Consequently,for the first time,a liquefaction triggering criterion,relating to effective overburden normalized liquefaction capacity energy(WL=s’c)to effective overburden stresscorrected shear wave velocity(eVs1)has been introduced.The accuracy of the proposed criteria was evaluated using in situ data.The results confirm the ability of shear wave velocity as a distinguishing parameter for separating liquefied and non-liquefied soils when it is calculated against liquefaction capacity energy(WL=s’c).However,the proposed WL=s’c-Vs1 curve,similar to previously proposed cyclic resistance ratio(CRR)-Vs1 relationships,should be used conservatively for fields vulnerable to liquefaction-induced lateral spreading. 展开更多
关键词 LIQUEFACTION Strain energy capacity Shear wave velocity cyclic triaxial test cyclic direct simple shear test Resonant column test Bender element test
下载PDF
Effect of rock joint roughness on its cyclic shear behavior 被引量:16
6
作者 S.M.Mahdi Niktabar K.Seshagiri Rao Amit Kumar Shrivastava 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2017年第6期1071-1084,共14页
Rock joints are often subjected to dynamic loads induced by earthquake and blasting during mining and rock cutting. Hence, cyclic shear load can be induced along the joints and it is important to evaluate the shear be... Rock joints are often subjected to dynamic loads induced by earthquake and blasting during mining and rock cutting. Hence, cyclic shear load can be induced along the joints and it is important to evaluate the shear behavior of rock joint under this condition. In the present study, synthetic rock joints were prepared with plaster of Paris(Po P). Regular joints were simulated by keeping regular asperity with asperity angles of 15°-15° and 30°-30°, and irregular rock joints which are closer to natural joints were replicated by keeping the asperity angles of 15°-30° and 15°-45°. The sample size and amplitude of roughness were kept the same for both regular and irregular joints which were 298 mm×298 mm×125 mm and 5 mm, respectively. Shear test was performed on these joints using a large-scale direct shear testing machine by keeping the frequency and amplitude of shear load under constant cyclic condition with different normal stress values. As expected, the shear strength of rock joints increased with the increases in the asperity angle and normal load during the first cycle of shearing or static load. With the increase of the number of shear cycles, the shear strength decreased for all the asperity angles but the rate of reduction was more in case of high asperity angles. Test results indicated that shear strength of irregular joints was higher than that of regular joints at different cycles of shearing at low normal stress. Shearing and degradation of joint asperities on regular joints were the same between loading and unloading, but different for irregular joints. Shear strength and joint degradation were more significant on the slope of asperity with higher angles on the irregular joint until two angles of asperities became equal during the cycle of shearing and it started behaving like regular joints for subsequent cycles. 展开更多
关键词 cyclic shear test Shear behavior Shear strength Regular joint Irregular joint Joint dilation Asperity degradation
下载PDF
Experimental Study on Cyclic Mechanics Characteristic of Saturated Soft Clay Strata 被引量:6
7
作者 李驰 王建华 石明磊 《Transactions of Tianjin University》 EI CAS 2006年第2期137-141,共5页
Failure criterion of saturated soft clay is studied under cyclic loads through different experiments. A large number of cyclic torsional shear and cyclic triaxial tests on saturated soft clay under unconsolidated undr... Failure criterion of saturated soft clay is studied under cyclic loads through different experiments. A large number of cyclic torsional shear and cyclic triaxial tests on saturated soft clay under unconsolidated undrained condition are conducted. From the test result analysis, it is seen that the failure of saturated soft clay under static and cyclic loads satisfies Mises criterion. The result from different test stress states is not related to the test stress states or confining pressures. It can be applied in general stress states. Then according to the Mises criterion, the equivalent relationship on failure moment between the test stress state and the general stress state can be established. So the cyclic mechanics characteristics of saturated soft clay at failure moment are clarified in this paper. Furthermore, a theory basis is provided for using pseudo-static elasto-plastic cyclic strength model to evaluate cyclic bearing capacity. 展开更多
关键词 ocean soil dynamics cyclic mechanics characteristic cyclic torsional shear test cyclic triaxial test failure criterion
下载PDF
A five-parameter constitutive model for hysteresis shearing and energy dissipation of rock joints 被引量:3
8
作者 Yikun Li Tongbin Zhao +1 位作者 Yifei Li Yang Chen 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2022年第4期737-746,共10页
Rock joints exhibit hysteresis shearing behavior and produce energy dissipation under shear cyclic loads,which however cannot be accurately depicted by existing constitutive models. This paper establishes a constituti... Rock joints exhibit hysteresis shearing behavior and produce energy dissipation under shear cyclic loads,which however cannot be accurately depicted by existing constitutive models. This paper establishes a constitutive model for hysteresis shearing and associated energy dissipation of rock joints. Analytical expressions of the model during cyclic shearing processes are derived. Derivation of the model indicates no energy dissipation in the elastic stage. When the shear load exceeds elastic boundary, nonlinear energy dissipation takes place. Validations with experiments show that the proposed model provides good conformities with direct shear curves and hysteresis loops, and can predict the energy dissipation characteristics of rock joints under different working conditions. Compared to the constitutive models using Weibull's distribution, the proposed one is smooth at the elastic boundary and can accurately capture the maximum shear stress. Unlike the existing incremental-type models, the proposed one provides clear and direct analytical expressions for both shear stress and energy dissipation during the whole displacement domain, which is more convenient in application. 展开更多
关键词 Iwan model Rock joint cyclic shear HYSTERESIS Energy dissipation
下载PDF
Constitutive Model of Saturated Soft Clay with Cyclic Loads under Unconsolidated Undrained Condition 被引量:3
9
作者 李书兆 王建华 《Transactions of Tianjin University》 EI CAS 2013年第4期260-266,共7页
An equivalent visco-elastic model of saturated soft clay was studied under unconsolidated undrained (UU) condition, which can be used to evaluate the stability of ocean foundation. Cyclic triaxial compression and exte... An equivalent visco-elastic model of saturated soft clay was studied under unconsolidated undrained (UU) condition, which can be used to evaluate the stability of ocean foundation. Cyclic triaxial compression and extension tests were conducted to study the parameters of the model. Results showed that the relationships of the damping ratio and the octahedral shear modulus with the octahedral cyclic shear strain were nearly unique, when the initial octahedral shear stress ratios of specimens were equal to 0.3, 0.5 and 0.7. The relationships of the damping ratio and the octahedral shear modulus with the octahedral cyclic shear strain determined from the cyclic triaxial compression tests were basically the same as those determined from the cyclic triaxial extension tests. Furthermore, the relationships were not related to the initial stress condition, the test stress state and the octahedral cyclic shear stress ratio. The relationships determined from the cyclic triaxial tests under no deviatoric stress were basically the same as those determined from the cyclic triaxial tests under deviatoric stress. The change of the octahedral cyclic accumulative strain with the number of cycles was unique under different tests stress states. An equivalent visco-elastic constitutive model of saturated soft clay under UU condition was initially established. 展开更多
关键词 visco-elastic constitutive model damping ratio octahedral cyclic shear modulus octahedral cyclic shear strain octahedral cyclic accumulative strain cyclic triaxial test
下载PDF
Probabilistic characterization of cyclic shear modulus reduction for normally to moderately over-consolidated clays 被引量:3
10
作者 Iok-Tong Ng Ka-Veng Yuen Ngai-Kuan Lao 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2016年第3期495-508,共14页
Evaluation of the cyclic shear modulus of soils is a crucial but challenging task for many geotechnical earthquake engineering and soil dynamic issues. Improper determination of this property unnecessarily drives up d... Evaluation of the cyclic shear modulus of soils is a crucial but challenging task for many geotechnical earthquake engineering and soil dynamic issues. Improper determination of this property unnecessarily drives up design and maintenance costs or even leads to the construction of unsafe structures. Due to the complexities involved in the direct measurement, empirical curves for estimating the cyclic shear modulus have been commonly adopted in practice for simplicity and economical considerations. However, a systematic and robust approach for formulating a reliable model and empirical curve for cyclic shear modulus prediction for clayey soils is still lacking. In this study, the Bayesian model class selection approach is utilized to identify the most significant soil parameters affecting the normalized cyclic shear modulus and a reliable predictive model for normally to moderately over-consolidated clays is proposed. Results show that the predictability and reliability of the proposed model out performs the well-known empirical models. Finally, a new design chart is established for practical usage. 展开更多
关键词 Bayesian analysis cyclic shear modulus empirical model geotechnical earthquake engineering normally tomoderately over-consolidated clays
下载PDF
Cyclic Shear Tests on Key Connection Joints of Modularized Constructions
11
作者 Deshen Chen Xiaofei Jin +3 位作者 Huajie Wang Hongliang Qian Deci Chang Feng Fan 《Journal of Harbin Institute of Technology(New Series)》 CAS 2022年第3期13-20,共8页
Modularized construction is a new type of prefabricated building system with green environmental protection and excellent performance. There are few studies on the seismic performance of its key connection joint. This... Modularized construction is a new type of prefabricated building system with green environmental protection and excellent performance. There are few studies on the seismic performance of its key connection joint. This paper presents a new type of assembled connection joint for the high-rise modularized construction. Cyclic shear tests of full-scale joints were carried out, and the key indexes of their seismic performances including the hysteretic performance, ductility, and energy dissipation capacity were analyzed and obtained. The results show that the hysteresis loops of longitudinal and lateral cyclic shear tests were both plump in shapes. The ductility coefficients were 4.54 and 4.98, and the energy dissipation coefficients were 1.83 and 1.43, respectively. The test joint had good ductility and energy dissipation capacity. The positions of yield failure of specimens were mainly concentrated in the connection areas between the column and short beam or end-plate. The research can provide the technical reference for the seismic design and engineering application of related modularized constructions. 展开更多
关键词 modularized construction assembled connection joint cyclic shear test seismic performance
下载PDF
Critical Cyclic Stress Ratio of Undisturbed Saturated Soft Clay in the Yangtze Estuary under Complex Stress Conditions
12
作者 刘功勋 栾茂田 +2 位作者 唐小微 王忠涛 郭莹 《Transactions of Tianjin University》 EI CAS 2010年第4期295-303,共9页
There exists a critical cyclic stress ratio when sand or clay is subjected to cyclic loading. It is an index dis-tinguishing stable state or failure state. The soil static and dynamic universal triaxial and torsional ... There exists a critical cyclic stress ratio when sand or clay is subjected to cyclic loading. It is an index dis-tinguishing stable state or failure state. The soil static and dynamic universal triaxial and torsional shear apparatus de-veloped by Dalian University of Technology in China was employed to perform different types of tests on saturated soft marine clay in the Yangtze estuary. Undisturbed samples were subjected to undrained cyclic vertical and torsional coupling shear and cyclic torsional shear after three-directional anisotropic consolidation with different initial consoli-dation parameters. The effects of initial orientation angle of major principal stress, initial ratio of deviatoric stress,initial coefficient of intermediate principal stress and stress mode of cyclic shear on the critical cyclic stress ratio wereinvestigated. It is found that the critical cyclic stress ratio decreases significantly with increasing initial orientation angle of major principal stress and initial ratio of deviatoric stress. Compared with the effects of the initial orientationangle of major principal stress and initial ratio of deviatoric stress, the effect of initial coefficient of intermediate prin-cipal stress is less evident. Under the same consolidation condition, the critical cyclic stress ratio from the cyclic cou-pling shear test is lower than that from the cyclic torsional shear test, indicating that the stress mode of cyclic shear has an obvious effect on the critical cyclic stress ratio. The main reason is that the continuous rotation in principal stressdirections during cyclic coupling shear damages the original structure of soil more than the cyclic torsional shear does. 展开更多
关键词 complex stress condition undisturbed saturated soft clay critical cyclic stress ratio three-directional anisotropic consolidation cyclic coupling shear cyclic torsional shear
下载PDF
Atomic-Scale Insights into Damage Mechanisms of GGr15 Bearing Steel Under Cyclic Shear Fatigue
13
作者 Qiao-Sheng Xia Dong-Peng Hua +6 位作者 Qing Zhou Ye-Ran Shi Xiang-Tao Deng Kai-Ju Lu Hai-Feng Wang Xiu-Bing Liang Zhao-Dong Wang 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2024年第7期1265-1278,共14页
Alternating shear stress is a critical factor in the accumulation of damage during rolling contact fatigue,severely limiting the service life of bearings.However,the specific mechanisms responsible for the cyclic shea... Alternating shear stress is a critical factor in the accumulation of damage during rolling contact fatigue,severely limiting the service life of bearings.However,the specific mechanisms responsible for the cyclic shear fatigue damage in bearing steel have not been fully understood.Here the mechanical response and microstructural evolution of a model GGr15 bearing steel under cyclic shear loading are investigated through the implementation of molecular dynamics simulations.The samples undergo 30 cycles under three different loading conditions with strains of 6.2%,9.2%,and 12.2%,respectively.The findings indicate that severe cyclic shear deformation results in early cyclic softening and significant accumulation of plastic damage in the bearing steel.Besides,samples subjected to higher strain-controlled loading exhibit higher plastic strain energy and shorter fatigue life.Additionally,strain localization is identified as the predominant damage mechanism in cyclic shear fatigue of the bearing steel,which accumulates and ultimately results in fatigue failure.Furthermore,simulation results also revealed the microstructural reasons for the strain localization(e.g.,BCC phase transformation into FCC and HCP phase),which well explained the formation of white etching areas.This study provides fresh atomic-scale insights into the mechanisms of cyclic shear fatigue damage in bearing steels. 展开更多
关键词 cyclic shear fatigue Molecular dynamic simulation Bearing steels Plastic damage accumulation
原文传递
The Mechanism Analysis of Seafloor Silt Liquefaction Under Wave Loading 被引量:8
14
作者 Yang Shaoli , Shen Weiquan Yang Zuosheng \Assistant, The Institute of Estuarine and Coastal Studies, Ocean University of Qingdao, Qingdao 266003 . Professor, The Institute of Estuarine and Coastal Studies, Ocean University of Qingdao, Qingdao 266003 《China Ocean Engineering》 SCIE EI 1995年第4期375-386,共12页
The sediment in Chengbei area of the Huanghe (Yellow River) subaqueous delta is the object of a reseach project in this article. The accumulating and dissipating effects following the change of time are considered fir... The sediment in Chengbei area of the Huanghe (Yellow River) subaqueous delta is the object of a reseach project in this article. The accumulating and dissipating effects following the change of time are considered first in the study area and the distributing curves of excess pore water pressure along with time and depth in the soil stratum are gained; the possibility of silt liquefaction is evaluated using the computing values and the affecting depth of liquefaction is given. This paper quantitatively analyzes the dynamic response of seafloor soil under the cyclic loading of waves and makes an inquiry into the instable mechanism of soil. 展开更多
关键词 dynamic water pressure cyclic shear stress excess pore water pressure LIQUEFACTION structure connection
下载PDF
Stiffness Degradation of Undisturbed Saturated Soft Clay in the Yangtze Estuary Under Complex Stress Conditions 被引量:6
15
作者 栾茂田 刘功勋 +1 位作者 王忠涛 郭莹 《China Ocean Engineering》 SCIE EI 2010年第3期523-538,共16页
Stiffness degradation will occur due to the generation of accumulated pore pressure in saturated soft clays under cyclic loading. The soil static-dynamic multi-purpose triaxial and torsional shear apparatus in Dalian ... Stiffness degradation will occur due to the generation of accumulated pore pressure in saturated soft clays under cyclic loading. The soil static-dynamic multi-purpose triaxial and torsional shear apparatus in Dalian University of Technology was employed to perform different types of test on the saturated soft marine clay in the Yangtze Estuary. Undisturbed samples of the clay were subjected to undrained cyclic vertical and torsional coupling shear and cyclic torsional shear after three-directional anisotropic consolidation with different initial consolidation parameters. Investigated were the effects of the initial orientation angle of the major principal stress, initial ratio of deviatoric stress, initial coefficient of intermediate principal stress and continuous rotation of principal stress axes on the stiffness degradation. It is found that the degradation index decreases (or degradation degree increases) significantly with increasing initial orientation angle of the major principal stress and initial ratio of deviatoric stress. Compared with the effects of the initial orientation angle of the major principal stress and initial ratio of deviatoric stress, the effect of initial coefficient of intermediate principal stress is less evident and this trend is more clearly reflected by the results of the cyclic torsional shear tests than those of the cyclic coupling shear tests. At the same cycle number, the degradation index obtained from the cyclic torsional shear test is higher than that from the cyclic coupling shear test. The main reason is that the continuous rotation in principal stress directions during cyclic coupling shear damages the original structure of the soil more than the cyclic torsional shear does.Based on a series of experiments, a mathematical model for stiffness degradation is proposed and the relevant parameters are determined. 展开更多
关键词 undisturbed saturated soft clay complex stress condition stiffness degradation three-directional anisotropic consolidation continuous rotation of principal stress axes cyclic coupling shear test cyclic torsional shear test
下载PDF
Effect of Initial Principal Stress Direction on the Dynamic Characteristics of Carbonate Sand 被引量:1
16
作者 Yu Haizhen Zhao Wenguang +2 位作者 Wang Ren Li Jianguo He Yang 《Journal of China University of Geosciences》 SCIE CSCD 2005年第4期340-344,共5页
The dynamic characteristics of carbonate sand under wave loads are very important for constructions on the ocean floor. The initial principal stress direction has been known to exert some influence on the dynamic char... The dynamic characteristics of carbonate sand under wave loads are very important for constructions on the ocean floor. The initial principal stress direction has been known to exert some influence on the dynamic characteristics of sand during cyclic loading. In an effort to investigate this aspect of the problem, several series of cyclic undrained tests were carried out on a saturated and loose sample of carbonate sand using a geotechnical static and dynamic universal triaxial shear apparatus. In this test apparatus, a hollow cylindrical sand specimen is subjected to a simultaneous application of both triaxial and torsional modes of shear stresses, which brings about the continuous rotation of principal stress axes. The test results indicated that the initial principal stress direction has a considerable influence on the dy- namic strength of loose carbonate sand and with the increase of initial orientation of principal stress, dynamic strength will be reduced, the cyclic pore pressure increased, but the residual pore pressure reduced. 展开更多
关键词 triaxial-and-torsional coupling cyclic shear tests carbonate sand initial principal stressdirection cyclic strength anisotropic consolidation.
下载PDF
Characteristics of Pore Water Pressure of Saturated Silt Under Wave Loading 被引量:1
17
作者 高玉峰 张健 +1 位作者 沈扬 闫俊 《China Ocean Engineering》 SCIE EI 2010年第1期161-172,共12页
The characteristics of dynamic stress in the seabed under wave loading are constant principal stress and continuous rotation of the principal stress direction. Cyclic triaxial-torsional coupling shear tests were peffo... The characteristics of dynamic stress in the seabed under wave loading are constant principal stress and continuous rotation of the principal stress direction. Cyclic triaxial-torsional coupling shear tests were pefformed on saturated silt by the hollow cylinder apparatus under different relative densities, deviator stress ratios and vibration frequencies to study the development of pore water pressure of the saturated silt under wave loading. It was found that the development of pore water pressure follows the trend of "fast - steady - drastic". The turning point from fast to steady stage is not affected by relative density and deviator stress ratio. However, the turning point from steady to drastic stage relies on relative density and deviator stress ratio. The vibration cycle for the liquefaction of saturated silt decreases with increasing deviator stress ratio and increases with relative density. The vibration cycle for the liquefaction of the saturated silt increases with vibration frequency and reaches a peak value, after which it decreases with increasing vibration frequency for the relative density of 70%. But the vibration cycle for the liquefaction of saturated silt increases with vibration frequency for the relative density of 30%. The development of pore water pressure of the saturated silt is influenced by relative density and vibration frequency. 展开更多
关键词 SILT wave loading pore water pressure vibration frequency cyclic triaxial-torsional coupling shear rotation of principal stress
下载PDF
Experimental study on the shear behavior of the interface between cushion materials and the concrete raft 被引量:1
18
作者 Li Yaokun Han Xiaolei +1 位作者 Khaled Galal Ji Jing 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2018年第1期165-178,共14页
Cushion is a layer of granular materials between the raft and the ground. The shear behavior of the interface between the cushion and the raft may influence the seismic performance of the superstructure. In order to q... Cushion is a layer of granular materials between the raft and the ground. The shear behavior of the interface between the cushion and the raft may influence the seismic performance of the superstructure. In order to quantify such influences, horizontal shear tests on the interfaces between different cushion materials and concrete raft under monotonic and cyclic loading were carried out. The vertical pressure P_v, material type and cushion thickness h_c were taken as variables. Conclusions include: 1) under monotonic loading, P_v is the most significant factor; the shear resistance P_(hmax) increases as P_v increases, but the normalized factor of resistance μ_n has an opposite tendency; 2) for the materials used in this study, μ_n varies from 0.40 to 0.70, the interface friction angle δ_s varies from 20° to 35°, while u_(max) varies from 3 mm to 15 mm; 3) under cyclic loading, the interface behavior can be abstracted as a "three-segment" back-bone curve, the main parameters include μ_n, the displacement u_1 and stiffness K_1 of the elastic stage, the displacement u_2 and stiffness K_2 of the plastic stage; 4) by observation and statistical analysis, the significance of different factors, together with values of K_1, K_2 and μ_n have been obtained. 展开更多
关键词 cushion/raft interface shear behavior monotonic test cyclic test "three-segment" back-bone curve
下载PDF
Elastoplastic behavior of frozen sand-concrete interfaces under cyclic shear loading 被引量:1
19
作者 Jian CHANG Jian-kun LIU +2 位作者 Ya-li LI Qi WANG Zhong-hua HAO 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2022年第9期683-703,共21页
The resilient modulus,accumulated plastic strain,peak shear stress,and critical shear stress are the elastoplastic behaviors of frozen sand–concrete interfaces under cyclic shear loading.They reflect the bearing capa... The resilient modulus,accumulated plastic strain,peak shear stress,and critical shear stress are the elastoplastic behaviors of frozen sand–concrete interfaces under cyclic shear loading.They reflect the bearing capacity of buildings(e.g.highspeed railways)in both seasonal frozen and permafrost regions.This study describes a series of direct shear experiments conducted on frozen sand–concrete interfaces.The results indicated that the elastoplastic behaviors of frozen sand–concrete interfaces,including the resilient modulus,accumulated plastic strain,and shear strength,are influenced by the boundary conditions(constant normal loading and constant normal height),initial normal stress,negative temperature,and cyclic-loading amplitude.The resilient modulus was significantly correlated with the initial normal stress and negative temperature,but not with the cyclic-loading amplitude and loading cycles.The accumulated plastic shear strain increased when the initial normal stress and cyclic-loading amplitude increased and the temperature decreased.Moreover,the accumulated plastic shear strain increment decreased when the loading cycles increased.The accumulated direction also varied with changes in the initial normal stress,negative temperature,and cyclic-loading amplitude.The peak shear stress of the frozen sand–concrete interface was affected by the initial normal stress,negative temperature,cyclic-loading amplitude,and boundary conditions.Nevertheless,a correlation was observed between the critical shear stress and the initial normal stress and boundary conditions.The peak shear stress was higher,and the critical shear stress was lower under the constant normal height boundary condition.Based on the results,it appears that the properties of frozen sand–concrete interfaces,including plastic deformation properties and stress strength properties,are influenced by cyclic shear stress.These results provide valuable information for the investigation of constitutive models of frozen soil–structure interfaces. 展开更多
关键词 Frozen sand-concrete interface cyclic direct shear test Elastoplastic behavior Direction of accumulated plastic strain Boundary condition
原文传递
Macro- and micromechanical evaluation of cyclic simple shear test by discrete element method 被引量:1
20
作者 Mozhgan Asadzadeh Abbas Soroush 《Particuology》 SCIE EI CAS CSCD 2017年第2期129-139,共11页
Direct simple shear tests are considered to be simple laboratory tests that are capable of imposing a cyclic loading that is analogous to that induced by earthquakes. A realistic evaluation of the test results demands... Direct simple shear tests are considered to be simple laboratory tests that are capable of imposing a cyclic loading that is analogous to that induced by earthquakes. A realistic evaluation of the test results demands a profound micromechanical investigation of specimens. Three-dimensional discrete element method models of a stacked-ring simple shear test were constructed, in which monotonic and cyclic loadings were applied under constant-volume conditions, and good agreement between the monotonic and cyclic macromechanical behaviors was noted. Micromechanical properties of specimens that were subjected to a cyclic loading are discussed in terms of lateral and intermediate principal stress development, fabric anisotropy, and principal stress rotation. The stress and strain states inside the specimen were investigated and it was shown that despite the uniform stress distribution inside the specimen, the volumetric strain distributes non-uniformly during loading and the non-uniformity grows with cycling, which leads to localized zones of dilative and contractive behavior. 展开更多
关键词 Discrete element method Direct shear test Simple shear test cyclic loading
原文传递
上一页 1 2 下一页 到第
使用帮助 返回顶部