【作者】 孙涛；

【导师】 栾茂田； 洪勇；

【作者基本信息】 大连理工大学 ， 岩土工程， 2008， 硕士

【摘要】 滑坡是地质灾害的主要类型之一,其中很多边坡发生了高速、长距离的滑动破坏,其滑动距离长达几十米、甚至上百米,这类滑坡造成的危害和损失也是最大的。因此,有必要对这种高速、长距离的滑坡灾害进行详细的试验研究。由于常规直剪仪和三轴仪受其应变范围所限无法满足这种大剪切位移的试验条件,而作为主要用于研究土在大剪切位移条件下土的力学特性的环剪仪具有其独特的设计构造和试验功能,已经逐渐扩展到涉及与土体剪切破坏过程相关的研究当中。目前,环剪仪在土的应变软化研究方面正发挥着越来越重要的作用。本文是在广泛查阅和收集资料的基础上,借鉴国内外的研究成果,利用吉林大学的大型高速环剪仪对典型的长春第四纪粉质黏土进行了试验研究,并得出了一些有意义的结论,为今后的研究工作提供了一定的参考。论文具体完成的内容:(1)回顾了国内外在峰后软化、残余强度、循环荷载对黏土抗剪强度的影响等方面的研究成果,针对实际的工程现状,阐述了本文的现实研究意义。(2)详细研究了环剪仪的发展历史、基本组成和主要功能,并对试验用料、试样制备等方面的内容进行了详细的阐述。(3)广泛查阅有关测定黏土残余强度的试验方法,并对各种试验方法进行了分析比较,同时总结了影响残余强度的主要因素。(4)通过多组试验,得出了超固结比、法向应力和剪切速率对超固结饱和黏土的峰值强度、残余强度和软化特性的影响结果,同时得到了残余强度在施加循环荷载前后的变化情况。试验还得到了频率、振动方向两个主要影响因素对循环荷载下土体应变软化和残余强度的影响结果。更多还原

【Abstract】 Landslide is one of the main geological disasters. Many landslides occur high speed and long distance sliding failure, and the sliding distance often amount to more than ten meters, even upper hundred meters. Damage and loss that this landslide brings about are also the maximal. Therefore, it’s necessary to carry out detailed experiments on this high speed and long distance landslide disaster.Since conventional direct shear apparatus and triaxial apparatus can’t satisfy this long shear displacement by whose strain range, as being used to study soil mechanics in large shear distance, ring shear apparatus has distinctive design and test functions, and already expand to the research field involving soil shear failure process. At present, ring shear apparatus play an important role in research on strain softening aspect.This paper is based on looking up and collecting datum broadly, and use home and abroad researches for reference. Researches were conducted on representative Changchun Q₂ silty clay by employing ring shear apparatus in Jilin University. Tests reached a few meaningful conclusions, and it will provide certain reference to further researches. The main work is following as:（1） Looking back to the history and development of researches on aspects of softening, residual strength and impact of cyclic load over clay shear strength. Be aimed at actual projects, research significance of this paper were set forth.（2） Detailed researches were carried out on history, fundamental composition and main functions of ring shear apparatus, and detailed expounding on material and sample preparation was also carried out（3） Look up experiment method about measuring clay residual strength broadly, and carried out analysis and comparison on various experiment methods. Meanwhile, the major factors affecting clay residual strength were summed up.（4） Tests reach results of peak strength, residual strength and softening characters of over-consolidation clays influenced by over-consolidation ratio, normal stress and shearing speed. Meanwhile, the variation of residual strength before and after applying cyclic load was reached. This paper also got the results of soil strain softening and residual strength under cyclic load influenced by frequency and vibrating direction.更多还原