膨胀性黄土隧道大变形演化特征及支护对策研究

发布时间：2018-04-14 01:09

本文选题：膨胀性黄土隧道 + 大变形演化特征　；参考：《山东大学》2014年硕士论文

【摘要】：自人类在黄土地区开展工程建设以来,黄土的力学特性及防护一直都是科学家们千百年来奋斗的科学问题。但由于在工程施工前期,对黄土膨胀特性及围岩大变形机理认识不清,往往出现常规设计、施工无法保证隧道施工安全的问题。因此,研究膨胀性黄土隧道大变形演化特征,提出有效控制膨胀性黄土隧道大变形的支护技术是黄土地区隧道建设亟需解决的核心技术难题。本文依托2011年度铁道部科技研究开发计划课题“膨胀性黄土隧道大变形演化特征及施工关键技术研究”,以某膨胀性黄土隧道为工程背景,针对膨胀性黄土隧道大变形演化特征及支护对策的研究,采用了现场观测、监测试验和数值模拟相结合的研究方法开展了相关研究。 (1)利用条分法分析隧道塌方与山体滑坡关系,对比研究隧道理论松动荷载值与实际围岩压力值,揭示出膨胀力是造成该隧道塌方的主要因子；基于收敛-约束理论,向围岩特征曲线中引入膨胀力,建立了降雨诱发上覆湿陷性黄土湿陷开裂,形成入渗通道,引起隧道围岩膨胀性黄土膨胀泥化,产生的膨胀力导致隧道常规支护强度不足,引起隧道膨胀性围岩大变形演化发展,诱发大体积塌方的破坏模式。 (2)基于热膨胀与增湿膨胀外在形式的相似性,利用ABAQUS具有的材料热膨胀理论模拟了膨胀性黄土隧道洞周土体膨胀变形,基于强度折减法,开展了膨胀性黄土隧道在不同膨胀应力作用下的隧道大变形演化过程研究,并求解了隧道围岩储备安全系数,综合现场实际记录和数值模拟结果提出了相应隧道初期支护施工建议。 (3)基于膨胀性黄土隧道的破坏模式及围岩变形规律,提出了“钢拱架+钢格栅”联合支护技术。利用前人的研究成果从不同角度分析了钢拱架与钢格栅的不同,利用数值模拟技术模拟了四种支护工况的支护性能,开展了“钢拱架+钢格栅”联合支护机理研究。 (4)以太兴铁路某膨胀性黄土隧道为依托,工程应用了“一榀型钢拱架+一榀钢格栅”的联合支护技术,通过拱架应力监测、现场围岩变形监测对联合支护技术的支护效果进行了评价,评价结果表明联合支护技术对膨胀性黄土隧道围岩变形有良好的控制作用,可以应用于现场实践。
[Abstract]:The mechanical properties and protection of loess have been a scientific problem for thousands of years since the engineering construction was carried out in loess area.However, in the early stage of engineering construction, the problem of tunnel construction safety can not be guaranteed because of the unclear understanding of loess expansion characteristics and large deformation mechanism of surrounding rock, which is often caused by conventional design.Therefore, studying the evolution characteristics of large deformation of expansive loess tunnel and putting forward the supporting technology of controlling the large deformation of expansive loess tunnel is the key technical problem that needs to be solved in tunnel construction in loess area.In this paper, the engineering background of an expansive loess tunnel is based on the project of the Ministry of Railways Research and Development Program of Science and Technology in 2011, "study on the Evolution characteristics of large deformation and key Construction Technology of expansive Loess Tunnel", and take a certain expansive loess tunnel as the engineering background.Based on the study of evolution characteristics of large deformation and supporting countermeasures of expansive loess tunnel, the research methods of field observation, monitoring test and numerical simulation are used to carry out related research.1) analyze the relationship between tunnel collapse and landslide by slice method, compare the theoretical loosening load value with the actual surrounding rock pressure value, reveal that the expansion force is the main factor causing the tunnel collapse, based on the convergence-constraint theory,The expansion force is introduced into the characteristic curve of surrounding rock, the overlying collapsible loess collapsibility cracking induced by rainfall is established, and the infiltration channel is formed, which causes the swelling loess swelling mudding of surrounding rock of tunnel, which results in the insufficient conventional support strength of the tunnel.It leads to the evolution and development of large deformation of tunnel expansive surrounding rock and the failure mode of mass collapse.2) based on the similarity of the external forms of thermal expansion and humidification expansion, the swelling deformation of soil around the cavity of expansive loess tunnel is simulated by using the material thermal expansion theory of ABAQUS, which is based on the strength reduction method.In this paper, the evolution process of large deformation of expansive loess tunnel under different expansive stress is studied, and the safety factor of tunnel surrounding rock reserve is solved.Based on the actual site records and numerical simulation results, the corresponding initial supporting construction suggestions are put forward.Based on the failure mode of expansive loess tunnel and the deformation law of surrounding rock, the combined support technology of steel arch frame steel grid is put forward.The difference between steel arch frame and steel grid is analyzed from different angles by using the previous research results. The support performance of four kinds of supporting conditions is simulated by numerical simulation technology, and the mechanism of "steel arch frame steel grid" combined support is studied.Based on an expansive loess tunnel of Taixing railway, the combined support technology of "one steel arch frame and one steel grid" is applied in the project, and the stress of the arch frame is monitored.The effect of combined support technology is evaluated by monitoring the deformation of surrounding rock on site. The evaluation results show that the combined support technology has good control effect on surrounding rock deformation of expansive loess tunnel and can be applied to field practice.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U451;U455.7

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