原状黄土剪缩性测试与理论分析  

TESTING AND THEORETICAL ANALYSIS ON CONTRACTIVE BEHAVIOR OF UNDISTURBED LOESS

作　　者：周跃峰[1,2] 谭国焕[2] 甄伟文[2] 

机构地区：[1]长江科学院水利部岩土力学与工程重点实验室,湖北武汉430010 [2]香港大学土木工程系

出　　处：《岩石力学与工程学报》2015年第6期1242-1249,共8页Chinese Journal of Rock Mechanics and Engineering

基　　金：香港研究资助局资助项目(HKU7140/08E)

摘　　要：为揭示剪切过程中黄土的应力–剪缩规律,在黑方台典型滑坡后壁获取原状试样,开展饱和黄土的等压固结不排水试验、等压固结排水试验与非饱和黄土的常含水率试验,探讨该黄土的应力–应变规律和临界状态强度,调查该黄土的状态参数与剪缩/剪胀行为,并进一步结合经典剪胀方程进行对比研究。研究结果表明:(1)该饱和黄土在上覆荷载应力范围以内的临界状态线可近似为一条直线,在94~100 kPa基质吸力条件下非饱和黄土的临界状态线也可简化为一条与前者平行的直线;(2)该黄土总体表现为剪缩趋势或剪缩变形,但是受初始孔隙比、初始应力水平影响,该黄土可能表现出剪胀行为;(3)该原状土可用土的状态参数描述,且亦可表现出剪缩–剪胀的相转化行为;(4)剑桥模型的剪胀方程总体上能够反映该黄土的剪缩行为。To reveal the contraction of loess in shearing,undisturbed specimens were obtained from the backwall of a typical landslide in Heifangtai. Three series of triaxial tests were carried out, including the isotropically consolidated undrained tests, isotropically consolidated drained tests for saturated loess and the constant water content tests for unsaturated loess. The stress-strain relationship and the critical state strength of the loess were explored. The state parameters and the contractive/dilative behavior of the loess were investigated. The contraction/dilation of the loess was studied based on the classical dilation equations. The unique critical state line of the saturated soil represented the major stress level corresponding to the thickness of Heifangtai loess. The critical state line for the unsaturated soil with the suction of 94 to 100 kPa was found to roughly parallel to the saturated one. The loess demonstrated normally a tendency of shearing contraction, but showed a tendency of dilation sometimes due to the initial void ratio and initial stress level. The undisturbed loess was described with the state parameters to reflect the transition from contraction to dilation. The contractive behavior of the loess was described with the dilation equation in the Cam-clay model.

关 键 词：土力学 黄土 非饱和土 临界状态 剪缩 剪胀理论 状态参数 

分 类 号：TU444[建筑科学—岩土工程]