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地下硐室围岩松动圈的地震反应研究

Study on Wall Rock Broken Zone’s Earthquake Response of Underground Chamber

【作者】 孙有为

【导师】 薄景山;

【作者基本信息】 中国地震局工程力学研究所 , 岩土工程, 2010, 博士

【摘要】 地下空间大规模的开发和利用是当前城市发展建设的必然趋势。尽管我们的祖先在远古时代就学会了利用洞穴而居,但是人类从工程建设意义上开发和利用地下空间还不到2000年的历史。20世纪中后期是人类开发利用地下空间比较活跃的时期,在这期间科学界和工程界积累了大量的有关地下空间的勘测、设计和施工方面的知识。随着地下工程的增多,破坏性地震对地下工程损坏的震例不断增加,地下工程的抗震问题成为学术界和工程界关注焦点,是当前岩土工程抗震领域研究的热点问题之一。本文全面系统地归纳、总结和评述了当前地下工程抗震领域的前沿成果和相关文献,对该领域的国内外研究现状和发展方向有了基本的了解。系统的总结了国内外地下结构地震反应分析的方法,在分析归纳已有地下工程震害资料的基础上,总结了隧道工程的各种破坏形式。本文利用数值分析的方法,围绕地震作用下地下硐室围岩压力变化特征、硐室围岩松动圈的扩展方式和硐室围岩松动圈的判定三个方向开展研究工作,取得了如下主要研究成果。1、开发了用于地下工程地震稳定性分析的有限差分程序(FLAC软件)。在有限差分程序FLAC内置的动态分析模块的基础上,对本构模型、边界条件、动力荷载的输入和数值试验模型的设计以及表达方式进行了改造和处理,使其更加方便地用于地下工程的地震稳定性分析。2、研究了地震硐室围岩在不同强度的地震动输入下的动力反应。给出了硐室有衬砌和无衬砌两种情况下围岩压力的变化情况,并与围岩静压力进行了分析和比较,总结了地下硐室围岩压力随地震动强度的变化趋势。研究发现,硐室衬砌对地震反应有较大的影响,硐室衬砌在一定程度上削弱了地震动的影响。3、利用数值分析的方法,模拟了地下硐室围岩松动圈在地震作用下的扩展过程,展现了不同地震波作用下,不同时间过程的扩展图像,总结给出了地震作用地下硐室围岩松动圈的扩展过程和主要特征。4、本文提出了地震作用下地下硐室围岩松动圈的初步判定方法。这种方法主要是基于硐室开挖前后,在考虑衬砌的情况下,通过对比不同计算点的地震反应来判定地下硐室围岩松动圈的近似范围。本文提出了判定的标准以及松动圈的范围和地震动加速度峰值大小的近似关系。

【Abstract】 Exploitation and utilization of underground space is Inevitable trend of the current urban development. Although our ancestor has learned how to change caves habitable, the history, which the human being exploit and utilize underground space in the engineering sense, is less than 2,000 years. The late 20th century is an active period of underground space’s exploitation and utilization. During this period, the scientific and engineering researchers accumulated a lot of knowledge about the underground space exploration, design and construction. With the increase of underground constructions, the case of underground engineering disaster caused by destructive earthquake also increased. Underground seismic problems become the focus of academic and engineering research. They also become one of the hot points in geotechnical seismic engineering.The article summarizes and comments on latest results and related literature of underground seismic engineering comprehensively and systematically. It gives the readers basic understanding about current research and the future research interests in this field. It also summarized domestic and foreign analysis methods about underground structures earthquake response and failure modes of tunnel engineering that based on analyzing and summarizing current seismic hazard materials. By using numerical analysis, the article makes studies on three problems which are under earthquake: features of underground chamber’s wall rock pressure variation, broken zone’s extended mode of underground chamber’s wall rock and determination method of underground chamber’s broken zone.1. Enhanced finite difference software (FLAC) to do the analysis of seismic stability of underground engineering. Based on the dynamic analysis module of finite difference software (FLAC), the author has done some transformation and processing of constitutive model, boundary conditions, dynamic load of the input, numerical test model design and expression so as to make it more convenient for the underground seismic stability analysis.2. The article analysis the response of underground chamber’s wall rock pressure, which is caused by different levels of peak ground motion acceleration. It simulates the result of wall rock pressure’s variation in two conditions: lining cavity and no-lining cavity, then analyses the results and compares all them with static pressure. It summed up the trend of underground chamber’s wall rock pressure, which caused by ground motion intensity. The researches show that chamber lining has great impact on underground chamber’s earthquake response. It can weakened the impact of ground motion in some extent.3. By using numerical analysis method, the article simulates the broken zone’s extended mode of underground chamber’s wall rock. The results are some images of broken zone’s extended trend, which on different time and effected by different seismic waves. It gives expansion process and main features of underground chamber’s broken zone under earthquake.4. The article gives preliminary determination method of underground chamber’s broken zone under earthquake. The main idea of this method is comparing all monitoring points’ results of earthquake response, which are calculated under earthquake in the model of lining chamber before and after excavation, to determine the approximate range of underground chamber’s broken zone. The article puts forward a standard of judgment of underground chamber’s broken zone under earthquake and approximate relationship between the range of broken zone and peak acceleration of ground motion.

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