连拱隧道围岩压力机理研究

发布时间：2018-03-25 13:37

本文选题：连拱隧道　切入点：压力拱　出处：《石家庄铁道大学》2014年硕士论文

【摘要】：近年来，随着我国铁路、公路和城市地铁的蓬勃发展，连拱隧道修建的数量也日趋增多。在大量建设的同时，设计和施工中的很多问题也暴露出来，因此有必要对其围岩压力计算方法展开研究。本文首先依据隧道弹塑性力学理论，采用数值模拟分析的方法，研究了隧道围岩内压力拱的形成规律，从而得到了单洞隧道围岩压力的计算方法，随后又讨论了施工过程对围岩压力的影响，进而得到了连拱隧道的围岩压力计算方法。论文主要研究工作及成果如下： (1)运用数值模拟软件建立单洞隧道的二维平面模型，研究压力拱的传力机理，以弹塑性理论为依据，确定出压力拱的影响范围，并进一步确定出压力拱的内外边界。压力拱内边界的判断条件为：将切向应力曲线与原岩应力曲线相交的位置为压力拱的内边界，如果开挖前后的切向应力不存在交点，则以隧道轮廓作为内边界。压力拱外边界的判断条件为：将开挖后的切向应力与原岩应力做差值，若得到的差值曲线的驻点前后斜率均很小，曲线平滑且稳定，则认为拱顶以上土体形成了有效的压力拱，差值曲线的驻点处即为压力拱的外边界。 (2)根据压力拱的受力机理研究，确定出基于压力拱理论的围岩压力计算方法。该方法认为围岩压力由二个部分组成：一部分为压力拱内边界以下的松动土体在自重的作用下产生的围岩压力，另一部分为压力拱内部由于形变产生的围岩压力。并参照Winkler模型的理论，详细阐述了由于压力拱的形变产生的围岩压力的计算方法。最后将这一计算方法与规范推荐的公式进行了比较与分析。 (3)基于压力拱理论的围岩压力计算方法会受到隧道埋深、隧道的跨度以及围岩物理力学参数等多个因素的影响，运用敏感性分析将以上因素进行逐个比较可以得到每个因素对围岩压力影响的强弱。考虑到隧道的围岩压力是由多个因素共同作用下的结果，为了找出各个因素与围岩压力的关系需要进行大量的相关计算，，由于考虑的因素较多，为了能在不影响分析结果的前提下减少试验次数，将正交试验作为研究手段，最后运用MATLAB软件的多元线性回归计算模块对正交试验得到的数据进行分析，得出便于工程实际应用的围岩压力计算公式。 (4)考虑施工过程对围岩压力的影响，利用有限元软件模拟隧道施工过程，主要分析先行导洞的形成对后行导洞上方围岩产生的扰动，进而对后行导洞围岩压力的影响。随后将考虑施工影响的隧道围岩压力计算结果与相同条件下单洞隧道的围岩压力计算结果进行比较，以围岩压力的比值作为连拱隧道施工过程的影响系数，最后将影响系数添加到基于压力拱理论的单洞隧道围岩压力计算公式中，得出适用于连拱隧道的围岩压力计算公式。
[Abstract]:In recent years, with the rapid development of railway, highway and urban subway in our country, the number of multi-arch tunnels is increasing day by day. At the same time, many problems in design and construction are also exposed. Therefore, it is necessary to study the calculation method of surrounding rock pressure. Firstly, according to the theory of elastic-plastic mechanics of tunnel, the formation law of pressure arch in tunnel surrounding rock is studied by using numerical simulation analysis method. Thus, the calculation method of surrounding rock pressure of single-hole tunnel is obtained, then the influence of construction process on surrounding rock pressure is discussed, and the calculation method of surrounding rock pressure of multi-arch tunnel is obtained. The main research work and results are as follows:. 1) the two-dimensional plane model of single-hole tunnel is established by using numerical simulation software, and the force transfer mechanism of pressure arch is studied. Based on elastic-plastic theory, the influence range of pressure arch is determined. The internal and external boundary of the pressure arch is further determined. The judgment condition of the inner boundary of the pressure arch is that the position where the tangential stress curve intersects with the original rock stress curve is the inner boundary of the pressure arch, if there is no intersection point between the tangential stress before and after excavation, Then the tunnel contour is taken as the inner boundary. The judgment condition of the external boundary of the pressure arch is as follows: the difference between the tangential stress after excavation and the stress of the original rock is made, if the slope of the difference curve before and after the stop point is very small, the curve is smooth and stable. It is considered that the soil above the arch has formed an effective pressure arch, and the rest point of the difference curve is the outer boundary of the pressure arch. 2) according to the stress mechanism of the pressure arch, The calculation method of surrounding rock pressure based on the theory of pressure arch is established. The method considers that the pressure of surrounding rock is composed of two parts: one is the pressure of the loose soil below the inner boundary of the pressure arch under the action of self-weight. The other part is about the surrounding rock pressure caused by deformation in the pressure arch, and referring to the theory of Winkler model, The calculation method of surrounding rock pressure caused by deformation of pressure arch is described in detail. Finally, the calculation method is compared and analyzed with the formula recommended by the code. 3) the calculation method of surrounding rock pressure based on pressure arch theory will be affected by many factors, such as tunnel depth, tunnel span and physical and mechanical parameters of surrounding rock, etc. Using sensitivity analysis to compare the above factors one by one, we can get the influence of each factor on the surrounding rock pressure, considering that the surrounding rock pressure of the tunnel is the result of the combined action of many factors. In order to find out the relationship between various factors and surrounding rock pressure, a large number of relevant calculations are needed. Because there are many factors to be considered, in order to reduce the number of tests without affecting the analysis results, orthogonal test is regarded as a research method. Finally, the data obtained by orthogonal test are analyzed by using the multivariate linear regression calculation module of MATLAB software, and the calculation formula of surrounding rock pressure is obtained, which is convenient for engineering application. (4) considering the influence of construction process on surrounding rock pressure, the tunnel construction process is simulated by finite element software, and the disturbance of the formation of pilot tunnel to surrounding rock above the rear guide tunnel is analyzed. Then, the influence of surrounding rock pressure on the surrounding rock pressure of the rear guide tunnel is compared with that of the single tunnel under the same conditions, and the calculation results of the surrounding rock pressure of the tunnel considering the influence of construction are compared with that of the single tunnel under the same conditions. The ratio of surrounding rock pressure is taken as the influence coefficient of the construction process of multi-arch tunnel. Finally, the influence coefficient is added to the calculation formula of surrounding rock pressure of single-hole tunnel based on pressure arch theory, and the calculation formula of surrounding rock pressure suitable for multi-arch tunnel is obtained.
【学位授予单位】：石家庄铁道大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U452.1

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