【作者】 李明；

【导师】 贺少辉；

【作者基本信息】 北京交通大学 ， 地下工程， 2012， 硕士

【摘要】 本文以新京张城际铁路八达岭地下车站为依托,查阅相关资料,对大跨度地下工程的研究现状、基于模糊数学的围岩分类的研究现状等有了一个基本的认识,然后根据前期的勘察和实验资料做了如下相关工作并且得到了一些研究成果：1.根据实验和勘察资料,在RMR分级的基础上通过模糊数学再次对围岩级别进行研究,根据评价结果可知,八达岭地下车站围岩,可以认为是三级偏弱,也可认为是四级偏强,如果考虑经济效益可选用三级围岩进行设计,如果考虑施工安全可选用四级围岩进行设计。2.根据八达岭地区花岗岩的常规三轴试验数据,对不同强度准对实验数据进行拟合。根据拟合结果,建议在工程实际中可采用Drucker-Prager强度准则。3.通过定性的方式研究跨度对围岩塑性区的影响。研究结果显示,第二主应力和地质条件等对塑性区有一定的影响。4.研究不同跨度、不同计算理论下作用在支护结构上的围岩压力。从围岩压力计算结果可知,普氏理论对于岩石坚固系数的依赖较高,计算结果偏于不安全；按太沙基理论和Bieniawski理论计算出的围岩压力最大,在深埋地下工程中不是很适用；按《公路隧道设计规范》计算出的围岩压力处于中间,具有一定的平均效果,可作为设计的参考。5.基于层次分析法研究断面形状和扁平率对围岩强度的影响。结果可知,不同断面的权重排序为：D3(椭圆形)>D4(圆形)>D2(马蹄形)>D1(矩形),即椭圆形断面方案最优。6.对扁平率为0.5-0.9的椭圆形断面的围岩应力状态进行对比,最后确定最优的扁平率。根据数值模拟结果的,结合国内外以往修建的大跨度地下工程的实际经验,发现埋深较大的大跨度地下工程扁平率控制在0.6-0.8之间较为合理,对八达岭地下车站,建议采用扁平率0.70进行设计施工7.研究不同施工步中围岩应力的变化,提出合理的开挖施工和支护方案。根据数值模拟的计算结果可知,随着施工的进行可能导致已开挖的部分拱顶稳定性变差,拱腰处应力集中程度变强,拱底有可能鼓起,所以施工过程中要加强对已开挖部分的监控量测,当发现不稳定迹象时及时采用支护措施进行处理。更多还原

【Abstract】 This paper is based on the engineering of Badaling underground station of the new Jing Zhang Inter-city rail. Read some relevant information and have a basic understanding about the current situation of large-span underground engineering and rock classification based on fuzzy mathematics, and then do the following work according to the pre-survey and experimental data k and get some research results:1. According to the experimental data and survey material, study the surrounding rock level again by fuzzy mathematics based on the RMR classification. According to the evaluation results known that the surrounding rock of the Badaling underground station can be considered the three on the weak side or four on the strong side, select the three level to design if consider the economic benefits, select the four level to design if consider the construction safety.2. Fit the different strength criterion based on the conventional triaxial test data of the Bdaling granite. According to the fitting results, it is recommended that the strength criterion of Drucker-Prager can be used in engineering.3. Study the impact of plastic zone by span of underground engineering through qualitative style. The results show that the second principal stress and geological conditions have a certain impact on the plastic zone.4. Study the rock pressure on the supporting structure by different span and different computing theory. Through the calculation results of the rock pressure, the Platt’s theory rely on a higher on coefficient of rock solid and the results of calculations are unsafe; the results of the calculations of the rock pressure by Terzaghi’s theory and Bieniawski’s theory rock pressure are maximum and are not fit to deeply engineering; the results of the calculations by Highway tunnel design specifications are in the middle and have some average effect, so it can be used as a reference design.5. Study the impact of rock strength by section shape and flat rate depending on the analytic hierarchy process. From the results get the order of the weight of the different sections:D₃（Oval）> D₄（Round）> D₂（horseshoe）> D₁（rectangular）, the shape of oval is the best.6. Study the surrounding rock stress state through changing the flat rate of the oval-shaped section from0.5to0.9and get the optimal flat rate by the results of the calculations. Through the numerical simulation results and combined with practical experience of large span underground works in the past, the flat rate of the large and depth span underground engineering should be controlled in the range of0.6to0.8. Chose the flat rate of0.70for the design and construction to the Badaling underground stations.7.Study the change of the surrounding rock stress of different construction steps and propose a suggestion of excavation、construction and support. According to the calculation results of the numerical simulation, the dome will become unstable and the degree of stress concentration of the arch waist will become higher and the arch bottom will muster with the conduct of the construction, so the monitoring and measurement should be strengthened, and the timely deal with supporting measures to when the discovery of signs of instability.更多还原