震区砾石土泥石流起动临界状态与力学性状

发布时间：2018-05-01 09:22

本文选题：汶川震区 + 砾石土　；参考：《山地学报》2017年04期

【摘要】：虽然汶川震区的松散砾石土历经近10年的自然固结过程,坡面植被恢复良好,但灾后持续活跃的泥石流等地质灾害告诉我们,了解这类因地震产生的砾石土的力学性状,仍然是理解灾区地质灾害肆虐的最重要的方面之一。本文以汶川县映秀镇牛圈沟泥石流源区的砾石土为研究对象,采用人工水槽模型试验与三轴测试,观察泥石流起动时砾石土的宏细观现象,分析粗细颗粒含量变化对砾石土干密度的影响,并从临界状态土力学角度,探讨了泥石流起动时砾石土的力学性状,提出砾石土临界状态数学表达式。结果表明:(1)泥石流起动时间、模式与初始干密度密切相关,其过程伴随着干密度和孔隙比的变化;(2)细颗粒迁移与粗细颗粒含量调整引起土体内部细观结构重组是干密度与孔隙比变化的主要原因;(3)相同级配的砾石土在等同围压条件下排水剪切,会近似达到一个临界孔隙比;(4)砾石土力学性状可根据其状态参数(e,p')与e_c-p'平面临界状态线的相对位置来判断;(5)砾石土边坡在降雨淋溶下失稳形成泥石流,坡体内同时存在剪胀与剪缩两种力学性状,且以剪胀为主。本文研究成果一方面能对泥石流起动机理的理论体系进行完善与补充,另一方面能为震区砾石土泥石流的防治预警预报提供初步依据。
[Abstract]:Although the loose gravel soil in Wenchuan earthquake area has undergone a natural consolidation process for nearly 10 years, and the vegetation on the slope has recovered well, the continuous and active geological disasters such as debris flow after the disaster tell us to understand the mechanical properties of this kind of gravel soil caused by the earthquake. It is still one of the most important aspects of understanding the ravages of geological disasters in disaster areas. In this paper, the gravel soil of Niuhuanggou debris flow source area in Yingxiu Town, Wenchuan County, is taken as the research object, and the macroscopical phenomenon of gravel soil during debris flow starting is observed by using artificial flume model test and triaxial test. The influence of coarse and fine particle content on dry density of gravel soil is analyzed. From the point of view of critical soil mechanics, the mechanical properties of gravel soil during debris flow starting are discussed, and the mathematical expression of critical state of gravel soil is put forward. The results show that the starting time and model of debris flow are closely related to the initial dry density. The process is accompanied by the change of dry density and porosity ratio.) Fine particle migration and the adjustment of coarse particle content are the main reasons for the change of dry density and porosity ratio. The gravel soil with the same gradation is the same. Drainage shear under confining pressure, The mechanical properties of gravel soil can be estimated according to the relative position between the critical state line and the critical state line of ec-p' plane. There are two kinds of mechanical properties in the slope, shear expansion and shearing contraction, and the shear dilatancy is the main one. On the one hand, the research results of this paper can perfect and supplement the theoretical system of debris flow starter, on the other hand, it can provide a preliminary basis for early warning and forecast of debris flow in gravel soil in earthquake area.
【作者单位】：广西大学土木建筑工程学院;工程防灾与结构安全教育部重点实验室;广西防灾减灾与工程安全重点实验室;中国科学院成都山地灾害与环境研究所;昆明理工大学国土资源工程学院;苏州市伟基基础工程有限公司;Department
【基金】：国家自然科学基金项目(41071058;41402272;51609041) 广西科技厅基金(2015 GXNSFBA139222) 广西防灾减灾与工程安全重点实验室项目(2016 ZDX09)~~
【分类号】：P642.23

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