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| ANALYSIS OF DYNAMIC STRESS STATE AND EFFECTIVE WORKING RADIUS IN SUBGRADE UNDER CONCENTRATED LOAD |
| TANG Liansheng1,2,LIN Peiyuan1,2,WU Ke1,DENG Xibin1,DING Qingfeng1,DENG Zhongwei1 |
(1. Department of Earth Science,Sun Yat-sen University,Guangzhou,Guangdong 510275,China;
2. Guangdong Province Key Laboratory of Geological Processes and Mineral Resources,Guangzhou,Guangdong 510275,China) |
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Abstract Based on the classical Boussinesq analytical solutions,a set defined by stress and strain state of points,when subjected to concentrated load,with varied spatial location in semi-infinite elastic subgrade and constrained by certain conditions,is employed to characterize the stress and strain state of a fixed point in the subgrade during the loading-unloading process induced by a single vehicle load. Dynamics,consequently,is transformed into quasi-statics,and analysis model,which is supposed to be convenient and practical for verifying subgrade dynamic behaviors,is established. Stress state and effective working radius are approached and determined during a loading—unloading process in subgrade. Results indicate:(1) curves of dynamic normal stress differences( ) and ( ) are pulse shape,while( ) changes in a twin peak manner;(2) the maximum principal stress might whirl abruptly about z axis,and the angle intersected with z axis rotates gradually and continuously by 180°;the orientation of minimum principal stress turns in a relatively smooth pattern and its rotation features are less remarkably;while the intermediate principal stress direction alters elusively;(3) effective working radius,which represents the limit of impacts exerted by a single vehicle loads on subgrade,pavement system,is suggested to a length of 10 m,and the influenced area can be considered as a semi-sphere with a radius of 10 m and whose center sited at the point of load. At last,the validity of effective working radius,which is defined by 10 m under one vehicle loading,is specified by in situ monitoring data.
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Received: 20 May 2011
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