国家自然科学基金项目41102180;成都理工大学地质灾害防治与地质环境保护国家重点实验室开放基金项目SKLGP2010K004;北京高等学校“青年英才计划”项目YETP0932;国家留学基金委公派访问学者项目No.201506435041.This work was supported by the National Natural Science Foundation of China41102180;the Open Foundation from State Key Laboratory of Geo-hazard Prevention and Geo-environment Protection of China,Chengdu University of TechnologySKLGP2010K004;the Young Elite Foundation of Universities in Beijing,ChinaYETP0932;the State Scholarship Fund for a Visiting Scholar from China Scholarship Council201506435041