The resilient and plastic behavior of subgrade soils under repeated loading and its model development.

• Main Authors: Shu-Jung Yang, 楊樹榮
• Other Authors: Wei-Hsing Huang
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/28309132970520575685

碩士 === 國立中央大學 === 土木工程研究所 === 90 === ABSTRACT The subgrade soil failures due to excessive permanent deformation produced by high stresses in the pavement. However, lack of reasonable mode distinguishes the critical stress in subgrade soil. This paper describes the shakedown behavior of cohesive subgrade soil under repeated loading. The main goal is to define the critical stress level of subgrade soil under repeated loading. According to the shakedown concept, this level is termed the shakedown limit, and it can be distinguish on bases of resilient, plastic, hysteretic, and shakedown behavior by repeated triaxial test. Besides, to select the deviatoric stress model and bilinear model predict the resilient modulus of subgrade soil. The test results show the bilinear model is better than the deviatoric stress model. The determination of critical stress can rely on the behavior of soil under repeated loading, such as dissipated energy and the type of plastic strain accumulation. Below the critical stress, the plastic strain is steady to accumulate, and the dissipated energy is more and more small as the number of load cycles increase. As the stress level advancing above the critical stress, the plastic strain is suddenly increases, and the dissipated energy rises again after specific load applications. Besides, the method of description for plastic strain rate versus plastic strain also can effectively distinguish the shakedown behavior. According to the shakedown concept, subgrade soil is from plastic creep shakedown to incremental collapse. The critical stress level is between two behaviors, and it decreases with increasing water content, increases with increasing confining pressure.