拉西瓦水电站地下厂房洞群监测资料反演分析与稳定性评价研究-岩土工程专业论文.docx

AbstractBACK Abstract BACK ANALYSIS AND盯ABlUTY ASSESSMENT FOR UⅨMfA UNDERGROUND POWERHOUSE SUBJECT：Geotechnlca-Engineering Date： Advisor：LI Ning Signature： Author：Jing Maogui Signature： It’s very difficult to accurately determine the mechanics parameters of the caves，the boundary and iIli廿al conditions,the best construction scheme and Sl：IPPoft parameters before the caves are excavated,SO there are a lOt of blindness,diseconomy and hiddan risks in the predasign of the caves．Based Oil the displacement measurement during the excavation process,the j11itial stress and mechanics parameters of the laxiwa under舀ound powerhouse are studied by the back analysis．Finally,the parameters by back analysis are used to predict the stability of surrounding rock mass of the caves during the later excavation．The major results in this paper can be summed up in following： (1)According to the regression and back analysis,the initial stress oflaxiwa吼derground powerhouse has been achieved,the three-dimensional distributing rule for initial stress is proposed，and is used in the later analysis，the stress data between the calculation and the measurement show a good coherence，which proves the feasibility ofthe simulation method． (2)Through change the k(modulus of horizontal slress)and the 11，1001igh to span)，this paper gives a systemic research on the deformation rule and plastic region by establishing a dyrmmie multi．step finite element model to simulate excavation process oflaxiwa underground powerhouse． (3)On foundation ofthe excavatiOn，displacement and deformation rule,the deformation and strength parameters ofdifferent areas are proposed in the back analysis。 (4)Aim atthe characteristic oflaxiwaundergroundpowerhouse，theestimatemethodsand standard晰 given in this paper． (5)Finally,the results ofback analysis ate used to predict the stability ofsurrounding rock mass during the later excavation；the prediction analyses results indicate that the whole stability of surrounding rock of undergrou