Study On Wall Rock Broken Zone's Earthquake Response Of Underground Chamber

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.