摘要
本文通过直剪试验、干湿循环试验和数理统计分析相结合的方法,研究干湿循环条件下,加砂比例变化对云南红土抗剪强度及微结构特性的影响,为云南红土在实际工程中的应用提供参考。结果表明:(1)当干湿循环次数一定时,随加砂比例的增大,红土内摩擦角非线性增加,黏聚力非线性减小;抗剪强度呈减小-增大-减小的波动变化趋势,且在加砂比例约10%左右存在极大值。(2)当加砂比例分别为0、5%、10%和15%时,随干湿循环次数的增加,红土内摩擦角降幅依次为22.8%、30.9%、19.9%、32.6%;黏聚力降幅依次为26.6%、29.2%、17.3%、37.7%;抗剪强度降幅依次为:23.6%、25.6%、18.7%、28.2%。红土颗粒数量降幅依次为35.7%、28.1%、22.7%、20%;孔隙率增幅依次为40.4%、36.5%、28.9%、23.6%;孔隙面积增幅依次为50.8%、42.9%、35.5%、30.7%。(3)干湿循环与加砂会改变红土微结构,其中定向度与定向分维数两个微结构参数与红土黏聚力的变化关系较为紧密;平均圆形度、孔隙面积、孔隙率等微结构参数对内摩擦角的影响较为显著。这些微结构参数与红土黏聚力和内摩擦角均为负相关,相关系数最高为-0.972,最低为-0.928。干湿循环、加砂比例对红土微结构及抗剪强度有显著影响。
Under the dry-wet cycle condition,the effect of sand addition proportion on shear strength and microstructure of Yunnan laterite was studied by the test of direct shear and wet-dry cycle and mathematical statistics analysis in this paper.The results can offer some reference for the engineering application of Yunnan laterite.The results showed:(1)When the number of the dry-wet cycle was constant,increasing of the sand proportion in the laterite led to a nonlinear increasing of the internal friction angle and a nonlinear decreasing of the cohesive force of laterite.The shear strength showed the change of down-up-down fluctuation with increasing of the sand proportion and the shear strength reached its maximum value when the sand proportion was approximately 10%.(2)Under the condition of increasing the number of dry-wet cycle,corresponding to the sand proportion in the laterite of 0,5%,10%and 15%respectively,the change range for the correlated variables was:the reduction of the internal friction angle 22.8%,30.9%,19.9%and 32.6%,the decreasing amount of the cohesion force 26.6%,29.2%,17.3%and 37.7%,the reducing amount of the shear strength 23.6%,25.6%,18.7%and 28.2%,the reduction of the laterite particle number 35.7%,28.1%,22.7%and 20%,the increasing amount of the pore rate 40.4%,36.5%,28.9%and 23.6%and the increase of the pore area 50.8%,42.9%,35.5%and 30.7%,respectively.(3)Under the effect of both the dry-wet cycle and the sand adding,the laterite microstructure can be changed.The test results indicated that the microstructure parameters both the orientation degree and the directional fractal dimensions had a closely relationship with the cohesion force,the internal friction angle was effected by the microstructure parameters like the mean circular degree,the pore area and the pore rate,etc.These microstructure parameters were all negatively related to the cohesion force and the internal friction angle,with the maximum correlation coefficient of-0.972 and the minimum correlation coefficient of-0.928.In a word,the dry-wet cycle and the sand adding proportion all significantly affected the laterite microstructure and the shear strength.
作者
梁谏杰
张祖莲
黄英
袁强
LIANG Jianjie;ZHANG Zulian;HUANG Ying;YUAN Qiang(College of Electrical Engineering,Kunming University of Science and Technology,Kunming 650500,China)
出处
《山地学报》
CSCD
北大核心
2019年第6期848-857,共10页
Mountain Research
基金
国家自然科学基金地区基金项目(51269006)。
关键词
红土
干湿循环
黏聚力
内摩擦角
加砂比例
微结构
laterite
dry-wet cycle
cohesion force
internal friction angle
sand adding proportion
microstructure
