摘要
为揭示降雨入渗条件下膨胀土膨胀各向异性对边坡破坏的作用机理,引入2个与基质吸力相关的弹性模量描述膨胀的各向异性行为,对非饱和土非线性弹性模型进行修正,并通过室内膨胀试验结果对模型的可靠性进行验证。通过二次开发和有限元计算软件,建立可考虑膨胀各向异性的非饱和膨胀土边坡数值计算方法。依托湖北安猇路实体工程,针对膨胀各向异性、膨胀各向同性和不考虑膨胀这3种工况,通过数值模拟得到降雨7 d内的膨胀土边坡内部湿度场和应力场分布与演变规律。根据摩尔-库仑强度理论,对比分析降雨入渗条件下边坡坡脚、坡中、坡顶处的应力状态变化。研究结果表明:侧向力预测结果与实测结果的相关性系数均大于0.9,修正后的本构模型可用于后续非饱和膨胀土边坡的数值模拟分析;与膨胀各向异性工况相比,膨胀各向同性和不考虑膨胀的工况下侧向应力最大值分别偏小20.8%~38.3%和73.9%~88.3%;膨胀土增湿过程中产生的膨胀压力将导致边坡内的应力重新分布,主应力轴由竖向旋转至侧向;坡脚将先于坡中和坡顶出现局部被动破坏;上部土体将失去坡脚的支撑并承受拉应力,致使破裂面逐步向上延拓,继而出现渐进式破坏。
In order to reveal the mechanism of slope damage caused by swelling anisotropy of expansive soil under the condition of rainfall infiltration,two elastic modulus with respect to matric suction were introduced to modify the non-linear elastic model of unsaturated soil,and the reliability of the modified model was verified by the results of laboratory swelling test.A numerical calculation method for unsaturated expansive soil slope considering the swelling anisotropy was established through subroutine development and FE software.Based on the engineering project of Anxiao Road in Hubei Province,the distribution and evolution of humidity field and stress field in expansive soil slope within 7 d due to rainfall were obtained by numerical simulation,considering anisotropic swelling condition,isotropic swelling condition and non-swelling condition,respectively.According to Mohr-Coulomb strength theory,the change of stress state at the foot slope,middle slope and top slope during rainfall infiltration were compared and analyzed.The results show that the correlation coefficient between the predicted lateral pressure and the measured lateral pressure is more than 0.9,the modified constitutive model can be used for the subsequent numerical simulation of unsaturated expansive soil slope.The maximum value of lateral pressure calculated in isotropic swelling condition and non-swelling condition would be underestimated by 20.8%−38.3%and 73.9%−88.3%,respectively,compared with the anisotropic swelling condition.The swelling pressure generated during the wetting process of expansive soil leads to the stress redistribution in the slope,and the major principal stress axis would rotate from the vertical direction to the lateral direction.Partial passive failure firstly occurs at the foot of the slope rather than the middle or the top of the slope.The upper part of the soil loses the support of the foot of the slope and bears the tensile stress,which causes the fracture surface to extend upward gradually,followed by progressive fa
作者
刘正楠
张锐
刘昭京
郑健龙
LIU Zhengnan;ZHANG Rui;LIU Zhaojing;ZHENG Jianlong(School of Traffic and Transport Engineering,Changsha University of Science and Technology,Changsha 410114,China;China Railway Nanning Group Co.Ltd.,Nanning 530029,China)
出处
《中南大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2022年第1期114-125,共12页
Journal of Central South University:Science and Technology
基金
国家自然科学基金资助项目(51978085)
中国国家铁路集团有限公司科技研究开发计划课题(K2020G036)
云南省交通运输厅科技创新及示范项目([2021]62)。
关键词
膨胀土
膨胀各向异性
数值模拟
边坡稳定性
浅层渐进式破坏
expansive soil
swelling anisotropy
numerical simulation
slope stability
shallow progressive failure
