冻结岩石节理面剪切力学性质研究

发布时间：2018-01-25 16:33

本文关键词： 冻结岩石节理面张开度粗糙度冰的粘附强度破坏形式峰值抗剪强度　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着国家西部大开发战略及振兴东北老工业基地战略的实施,在多年冻土区及季节冻土区修建的隧道工程数量越来越多。这些隧道工程中,有超过70%出现了不同程度的拱顶漏水挂冰、路面鼓胀积冰、衬砌开裂、洞口边坡支挡结构冻胀开裂等冻害,威胁隧道围岩及洞口边坡的稳定性。通过调查发现,多年冻土区隧道衬砌冻害产生部位多为围岩节理较为发育的地段;同时,洞口边坡支挡结构冻害也多发生在含有控制性结构面的节理岩体边坡地质条件下。由此可见,冻结条件下岩石节理面的剪切力学特性差异是造成多年冻土区隧道及洞口边坡冻害的根本原因。本文以青海省G214国道姜路岭路段的凝灰岩节理作为研究对象,选取4组不同粗糙程度的岩石节理面进行研究,得出了不同法向应力和张开度条件下的冻结岩石节理面峰值剪切强度,总结和分析法向应力和张开度与峰值剪切强度的变化规律,并分析了粗糙度对剪切强度的影响。通过观察试件的破坏形式,从力学角度和冰的粘附强度理论角度两方面对其破坏机理进行了分析,最后提出了冻结岩石节理面峰值抗剪强度准则。本文主要取得的研究成果如下:(1)根据不同法向应力条件下剪切试验得到的剪切应力——剪切位移曲线,一般情况整个试验过程分成了4个阶段,分别为:瞬时变形阶段、应力持续增加阶段、屈服阶段和残余剪切阶段。(2)得出了冻结岩石节理面的峰值剪切强度随着张开度的增大而降低,两者成负相关的关系,达到峰值剪切强度时的剪切位移与张开度也成负相关关系。(3)分析了节理表面形貌对冻结岩石节理面的峰值剪切强度的影响,在本文研究的张开度条件下得出了岩石节理面粗糙度越大其峰值剪切强度越小。(4)通过对试验破坏后的试件观察,发现试件在不同张开度条件下节理面的破坏形式区别很大。由此,从力学角度和冰的粘附强度理论角度两方面对整个试验的破坏机理进行分析,根据试件破坏形式不同,得出了3种破坏形式,分别为:冰层脱离破坏、冰层剪断破坏和冰岩剪断破坏。(5)通过剪切试验得到的峰值剪切强度值,根据试验结束后试件的破坏形式,得出不同张开度条件下的峰值抗剪强度准则。
[Abstract]:With the implementation of the strategy of developing western China and revitalizing the old industrial base in Northeast China, more and more tunnel projects have been built in permafrost regions and seasonal frozen regions. There are more than 70% cases of frost damage, such as different degree of water leakage and ice hanging, bulging and ice accumulation, lining cracking, frost heaving cracking of retaining structure of the slope at the entrance of the tunnel, and so on. Through the investigation, it is found that the site of tunnel lining frost damage in permafrost region is the section where the joint of surrounding rock is relatively developed. At the same time, the freezing damage of the retaining structure of the slope at the mouth of the tunnel also occurs mostly under the geological conditions of the jointed rock slope containing the control structure surface, so it can be seen. The difference of shear mechanical properties of rock joints under freezing condition is the fundamental cause of freezing damage of tunnel and portal slope in frozen soil region for many years. The tuff joint of G214 National Highway in Qinghai Province is studied in this paper. Elephant. The peak shear strength of frozen rock joints under different normal stress and opening degree is obtained by selecting four groups of rock joints with different roughness. The influence of roughness on shear strength is analyzed by summarizing and analyzing the variation law of directional stress, opening degree and peak shear strength, and the failure mode of specimen is observed. In this paper, the failure mechanism of ice is analyzed from the point of view of mechanics and the theory of ice adhesion strength. Finally, the criterion of peak shear strength of frozen rock joints is proposed. The main research results in this paper are as follows: 1) the shear stress-shear displacement curves obtained by shear tests under different normal stress conditions. In general, the whole test process is divided into four stages, namely, the instantaneous deformation stage and the stress increasing stage. It is concluded that the peak shear strength of frozen rock joints decreases with the increase of opening degree, and there is a negative correlation between them. The effect of the surface morphology of joints on the peak shear strength of frozen rock joints was analyzed. Under the condition of opening degree studied in this paper, it is concluded that the greater the roughness of rock joint surface is, the smaller the peak shear strength is. It is found that the failure modes of the joints are very different under different opening conditions. Therefore, the failure mechanism of the whole test is analyzed from the angle of mechanics and the theory of the adhesion strength of ice. According to the different failure forms of the specimens, three kinds of failure forms are obtained, which are: ice sheet breakaway, ice shear failure and ice rock shear failure. 5) the peak shear strength obtained by shear test. According to the failure form of the specimen after the test, the criterion of peak shear strength under different opening degree is obtained.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U451.2

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