摘要
利用原状多年冻土在不同切样角度下的直剪试验,探讨-2℃条件下青藏地区2种不同土性(粉土、粉质黏土)冻土的直剪力学特性。结果表明:原状冻结粉土含冰量变化较小,内部为层状构造,而原状冻结粉质黏土含冰量变化较大,可以看到冻土中有冰块;原状冻结粉土、原状冻结粉质黏土剪切位移(Δl)-剪应力(τ)曲线表现为硬化型;原状粉质黏土随着含冰量增加呈现脆性破坏的趋势;原状冻结粉土的抗剪强度受剪切角度的影响较大,在200 kPa法向应力作业下,不同剪切角度下得到的原状冻结粉土抗剪强度τ_(max)是τ_(min)的1.22倍。通过理论分析可知,在层理面上开展直剪试验,其抗剪强度最小;因此,对于高温原状多年冻土的抗剪强度的取值应考虑切样角度的影响。
The direct shear characteristics of two kinds of soils(silty soil and silty clay)under the condition of-2℃in Qinghai-Tibet region are tested by direct shear tests at different cutting angles of undisturbed permafrost.The results show that the ice content of undisturbed frozen silty soil varies little and has layered structure inside,while the ice content of undisturbed frozen silty clay varies greatly,indicating that there are ice cubes in the frozen soil.The shear displacement(Δl)-shear stress(τ)curves of undisturbed frozen silty clay and undisturbed frozen silty clay display strain hardening characteristics,and the original silty clay shows a brittle failure trend with the increase of ice content.During the experiment,the shear strength of undisturbed frozen silt is greatly affected by shear angle.Under the normal stress of 200 kPa,the shear strength τ_(max) of undisturbed frozen silt obtained at different shear angles is 1.22 times that of τ_(min).According to the theoretical analysis,when the direct shear test is tested on the bedding plane,the shear strength is the smallest.Therefore,the influence of sample cutting angle should be considered in the value of shear strength of undisturbed permafrost at high temperature.
作者
朱锋盼
赵晓东
李俊虎
付俊武
ZHU Fengpan;ZHAO Xiaodong;LI Junhu;FU Junwu(State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology,Xuzhou 221116,China;Jinhua Polytechnic,Jinhua 321017,China;China Construction Tunnel Co.,Ltd.,Chongqing 401320,China)
出处
《成都理工大学学报（自然科学版）》
CAS
CSCD
北大核心
2022年第5期616-622,640,共8页
Journal of Chengdu University of Technology: Science & Technology Edition
基金
国家自然科学基金项目(51304209)
住房和城乡建设部科学技术计划项目(2020-K-149)。
关键词
切样角度
高温原状多年冻土
直剪试验
抗剪强度
cutting angles
warm undisturbed permafrost
direct shear test
shear strength
