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首页> 中文期刊> 《山地学报》 >震区砾石土泥石流起动临界状态与力学性状

震区砾石土泥石流起动临界状态与力学性状

         
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摘要

Although gravel soils generated by seismic shaking in Wenchuan earthquake area have subjected to natural consolidation process for nearly ten years,geological hazards,such as slope failures with ensuing debris flows,frequently are haunting the area.To understand the nature of geohazard initiation,in this paper,artificial flume experiments and triaxial tests were used to make close observation on gravel soil samples,which were collected at Niujuan valley,Yingxiu Town of Wenchuan County,Sichuan Province,China.Based on the mechanical property analysis of gravel soil samples,some results relevant to the micro-macro property,action of coarse-fine particles content on dry density,and critical state of gravel soils in the process of motivating debris flow were confirmed:(1) The timing and patterns of debris flow initiations were closely related to their initial dry densities,and initiation processes were accompanied with a variation of dry density and void ratio;(2) Fine particle migration in soil and coarse-fine particle content rearrangement contributed to the internal micro structure reorganization,which was supposed to be the main reason for variation of dry density and void ratio;(3) Gravel soils with unchanged grain compositions,if under the same hydrostatic compression,they approached to an identical critical void ratio theshold to fail;(4) The mechanical state of certain sort of gravel soil can be identified by its relative position between state parameter (e,p') and ec-p'planar critical state line;(5) Gravel soil slope failed and then evolved into debris flow under lasting rainfall leaching,while in gravel slope there co-existed soil dilatation and contraction,but the dilatation was dominant.Above research findings not only could be used to interpret debris flow initiation but also would provide an insight for debris flow warning forecast of gravel slope in seismic area.%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ec-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.

著录项

  • 来源
    《山地学报》 |2017年第4期|506-516|共11页
  • 作者

    廖丽萍; 朱颖彦; 杨志全; 杨云川; 胡进; 邹代华; 罗晓宏;

  • 作者单位

    广西大学土木建筑工程学院,南宁530004;

    工程防灾与结构安全教育部重点实验室,南宁530004;

    广西防灾减灾与工程安全重点实验室,南宁530004;

    中国科学院成都山地灾害与环境研究所,成都610041;

    昆明理工大学国土资源工程学院昆明650093;

    广西大学土木建筑工程学院,南宁530004;

    工程防灾与结构安全教育部重点实验室,南宁530004;

    广西防灾减灾与工程安全重点实验室,南宁530004;

    苏州市伟基基础工程有限公司,江苏苏州215100;

    Department of Civil and Resource Engineering, Dalhousie University, Halifax,NS,Canada B3 H4 K5;

    湖北交通职业技术学院,武汉430074;

  • 原文格式 PDF
  • 正文语种 chi
  • 中图分类 工程地质学;
  • 关键词

    汶川震区; 砾石土; 泥石流; 临界状态; 力学性状;

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