基于物理模拟的山岭隧道外水压力分布规律研究

发布时间：2018-06-02 19:11

本文选题：山岭隧道外水压力物理模拟轴对称理论 + 　；参考：《成都理工大学》2017年硕士论文

【摘要】：外水压力作为山岭隧道建设可行性分析中不可忽略的关键因素,无论是对隧道选址方案还是其自身设计方案都会产生重要影响。由于对压力的监测难度较大,缺乏基于工程验证的隧道外水压力计算方法,因此目前对隧道外水压力的估算主要仍依靠经验对静水压力折减或采用纯理论公式估算,因而估算值与实际值往往相差甚远。因此,本文在简要讨论和总结山岭隧道物理模拟试验简化及分析所需的理论基石-地下水等效连续介质渗流模型理论体系的基础上,着重分析与讨论了地下水等效连续介质渗流模型在裂隙岩体中的适用条件为存在REV值且待测试样尺寸不小于该REV值及渗流为稳定渗流。然后基于对前人已有相关研究成果的分析与总结,通过举例及对比论证,分析得出了水文地质结构及边界条件等隧道区渗流水文地质控制要素对隧道外水压力的控制作用。最终以处于隧道轴线两侧等水头均质岩体水文地质控制要素(A1)和隧道轴线两侧等水头近水平均质层状水文地质控制要素(B1)中的隧道为研究对象,通过近似等效的静力学物理模拟试验讨论分析得出隧道在毛洞全排、零排水全封堵及衬砌堵排结合工况下,外水压力的分布规律如下:1毛洞全排工况下,无论隧道处于两种水文地质控制要素下的哪一种,其近场外水压力相对于边界水头在相应深度产生的静水压力有较大的折减,然而产生相应的问题就是过大的涌水量,长此以往易造成生态环境地质问题;且在同一边界水位条件下,围岩整体渗透性越小,隧道近场外水压力越大。2无论隧道处于A1还是B1类水文地质控制要素下,由于隧道上方的水位形态特征受隧道围岩渗透性影响较大,不易形成近水平的水面。因此在毛洞全排工况下,轴对称解析法估算衬砌测压水头只适用于在围岩渗透性较小的情况。3零排水全封堵工况下,隧道外水压力值即为其相应位置的静水压力值,只与隧道水下埋深有关。4对隧道采取衬砌堵排结合措施时,无论隧道处于A1类水文地质控制要素下还是处于B1类水文地质控制要素下,同一工况隧道衬砌表面上任意点测压水头近似相同,且与其他条件与之相同的毛洞工况隧道相比,其测压水头折减程度较小。5衬砌堵排结合工况下,对处于A1类水文地质控制要素的隧道采用轴对称理论解析法估算隧道衬砌的测压水头时,若两侧边界水位相对隧道中心位置高度不大于114m且衬砌渗透系数不大于0.008m/d,则估算值与实测值相比偏大且误差不大于2%。6衬砌堵排结合工况下,在上述结论的基础上并结合实测数据,采用假设及对比分析法可知:当隧道处于B1类水文地质控制要素下且位于底层渗透介质时,可近似采用轴对称理论解析法估算衬砌水压力,且kw值应近似取底层渗透介质的渗透系数。
[Abstract]:As a key factor in the feasibility analysis of mountain tunnel construction, the external water pressure will have an important impact on both the tunnel site selection scheme and its own design scheme. Because of the difficulty of monitoring the pressure and the lack of the calculation method of the tunnel water pressure based on engineering verification, the estimation of the tunnel external water pressure still mainly depends on the experience to reduce the hydrostatic pressure or to use the pure theoretical formula to estimate the pressure. As a result, the estimated value and the actual value are often far from each other. Therefore, this paper briefly discusses and summarizes the theoretical system of groundwater equivalent continuum seepage model, which is needed to simplify and analyze the physical simulation test of mountain tunnel. The suitable condition of groundwater equivalent continuum seepage model in fractured rock mass is the existence of REV value and the size of the sample to be tested is not less than the REV value and the seepage flow is stable seepage. Then based on the analysis and summary of the previous related research results, through the examples and comparative demonstration, the control effect of the hydrogeological control elements on the external water pressure in the tunnel area, such as the hydrogeological structure and boundary conditions, is obtained. Finally, the research object is the tunnel which is located in the hydrogeological control elements of the isobaric homogeneous rock mass on both sides of the tunnel axis (A1) and the near-horizontal homogeneous layered hydrogeological control element (B1) on both sides of the tunnel axis. Through the analysis of the approximate equivalent static physical simulation test, it is concluded that the distribution of external water pressure is as follows under the working conditions of the total row of the tunnel under the combined conditions of gross tunnel, zero drainage and lining plugging, and the pressure of the outer water is as follows: 1: 1 under the condition of the complete arrangement of the tunnel, No matter which of the two hydrogeological control elements the tunnel is under, the near field water pressure has a great reduction relative to the hydrostatic pressure produced by the boundary water head at the corresponding depth, but the corresponding problem is the excessive water discharge. Under the same boundary water level condition, the smaller the overall permeability of surrounding rock is, the greater the water pressure near the field of tunnel is, regardless of whether the tunnel is under A1 or B1 hydrogeological control elements. Because the water level over the tunnel is influenced by the permeability of surrounding rock, it is not easy to form near horizontal water surface. Therefore, the axisymmetric analytical method can only be used to estimate the hydrostatic pressure of the lining pressure head in the case of low permeability of surrounding rock and zero drainage under the condition of the full discharge of the tunnel, and the external water pressure of the tunnel is the hydrostatic pressure in the corresponding position. When the tunnel is only related to the underwater burial depth of tunnel, the tunnel is under the A1 hydrogeological control element or B1 hydrogeological control element, when the tunnel adopts the combined measures of lining and drainage, and the tunnel is under the hydrogeological control element of class A1 or the hydrogeological control element of the B1 class. The pressure measuring head at any point on the surface of the tunnel lining under the same working condition is approximately the same, and compared with other tunnel with the same conditions, the pressure measuring water head reduction degree is smaller than that of the tunnel under the combined condition of 5. 5 liner plugging and drainage. In this paper, the pressure head of tunnel lining is estimated by axisymmetric analytical method for the tunnel with A1 hydrogeological control elements. If the height of the water level on both sides of the boundary is not more than 114 m relative to the center of the tunnel and the permeability coefficient of the lining is not greater than 0.008 m / d, the estimated value is larger than the measured value and the error is not greater than that of the measured value. On the basis of the above conclusions and combined with the measured data, the hypothesis and comparative analysis method are used to show that when the tunnel is under the B1 hydrogeological control element and is located in the underlying permeable medium, The analytical method of axisymmetric theory can be used to estimate the water pressure of the lining, and the KW value should approximate the permeability coefficient of the underlying permeable medium.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U452.11

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