【作者】 李远；

【导师】 乔兰；

【作者基本信息】 北京科技大学 ， 岩土工程， 2008， 博士

【摘要】 在地下工程项目中,水电站地下厂房的建设由于其规模庞大、空间组成复杂、洞室间相互影响而关系到整个电站的安全运营和巨大的经济效益。对其设计方法和稳定性分析方法的研究已成为当前地下工程建设中亟待解决和值得深入探讨的重大课题。本文从大型洞室群所处岩体地应力场分布规律及其与地质构造关系、复杂几何体建模、本构关系推演等方面对大型洞室群围岩稳定性展开系统研究,并以辽宁本溪桓仁电站建设为工程背景对地下厂房开挖和支护的稳定性进行分析和探讨。在现场测量和室内实验的基础上得出地应力场分布与区域构造的关系;提出了复杂几何体构形及空间面、体关系运算算法,实现了FLAC3D软件复杂几何体直接建模和地质界面后期插入的功能;通过对厂房区地应力场的分布进行拟合研究获得了多种构造位移影响下的整体应力场分布规律;针对统一强度理论在岩石力学中应用较少和FLAC3D有限差分软件中缺少统一双剪力学模型的情况,推导出了基于统一双剪强度理论的有限差分计算形式,开发了FLAC3D的非关联统一双剪理论的力学模块,并据此开展统一双剪强度理论下的厂房区大型洞室群开挖和支护的稳定性分析。取得的主要成果有:(1)对桓仁电站地下厂房区采用空心包体应变计法进行了地应力测量,并结合室内和现场的实验分析,得到了厂房区地应力大小和方向,经过分析得出该地区地应力分布主要受新华夏系构造控制,最大主应力方向为北北西,大小为5~7MPa的结论;(2)针对FLAC3D模拟软件在复杂几何体建模上的困难,提出了二次切割下的准三维拉伸、四面体子块划分等建模前处理和后处理算法,实现了FLAC3D复杂几何体空间直接构形和地质界面后期插入的功能,扩展了FLAC3D建模功能,为厂房区地应力场拟合及大型洞室群稳定性分析建模进行了准备;(3)根据地应力实测数据和现场地质构造条件、地形地貌特征,对区域地应力场进行了数值模拟分析,以多元线性回归法实现了由点到体的电站地下厂房区地应力场拟合的计算,得到了各个单位构造位移的影响系数。以边界荷载提取法实现了应力边界和位移边界的变换,并以此实现了多种构造位移同时影响下的整体地应力场的模拟,得到了其分布规律并将其作为厂房洞室群稳定性计算中边界条件选取依据;(4)针对FLAC3D缺少统一双剪模型和统一强度理论的强度准则在岩石力学领域应用较少的情况,结合统一强度理论基本原理和有限差分计算迭代原则,推导出统一强度理论的有限差分计算形式。并考虑关联和非关联本构关系在岩土工程中的适用情况,提出了一种适合此理论有限差分计算的非关联流动法则,并开发了FLAC3D中统一双剪强度理论的塑性模块,使统一双剪这一新的塑性理论在有限差分计算中得以实现,也拓展了FLAC3D力学分析的适用性。采用数值模拟的方法对统一双剪力学模块进行检测验证,结果显示此模块很好的体现出了统一强度理论中第二主应力效应这一特点;(5)以统一双剪强度理论为塑性破坏依据,以边界荷载提取法取得模型精确的边界条件,开展了基于统一强度理论的桓仁电站地下厂房洞室群开挖和支护的稳定性分析,得到了洞室群开挖破坏区发展、分布规律和位移变化情况。更多还原

【Abstract】 In underground engineering, the construction of underground powerhouse in a hydropower station is often related to the safe operation of the whole station and enormous benefits because of its large scale, complicated space composing and effects between caverns. The theories in stability analyses and the methods of design are urgent heated issues.The effects of irregular surface, in-situ stress field’s distribution and different constitutive relations on stability have been studied in this paper. The stability of large caverns during the excavation and supported was analyzed in the case of the construction of Huanren powerhouse The relationships between the in-situ stresses and geological structures have been established by the data acquired from in-situ measurements and laboratory tests; the algorithms to establish the model under complex geologic conditions and to judge the relationships between faces and zones are proposed, and the pre-processing and post-processing functions of complex model’s assembling and interfaces’inserting were realized; the factors effecting on the value of in-situ stresses, and the model of the stress field’s distribution in powerhouse zone by multiple linear regression were analyzed, the distribution of the whole stress field effected by many factors was obtained; since the unified strength theory has seldom been used in rock mechanics, there’s not corresponding constitutive models in FLAC3D, the special unified double shear modules with a non-associated flow rule for the FLAC3D was developed, base on the unified strength theory the stability of the underground caverns with large scale was analyzed. The main achievements are shown as below:(1) The values and directions of the in-situ stresses in powerhouse area were measured with the method of CSIRO cells, the relationships between the stress and the new cathaysian structures were established. The direction of the max principal stress is about 280o, and the corresponding range of the value is about from 5 to 7MPa.(2) According to the difficult of FLAC3D software in building models with irregular surfaces, the algorithms of quasi-three dimension models’stretching after zones’sub-divided and tetrahedron shaped sub-zones’dividing to establish the models with irregular surfaces and to insert the interfaces to the assembled zones were proposed. (3) According to the data acquired from the measurements and the geological conditions, distribution of the in-situ stress field was obtained by multiple linear regression, which can be served as the basis of boundary conditions.(4) Based on the principles of united strength theory and fast lagrangian analysis of continua in 3D, finite-difference forms of the unified strength theory was deduced, and non-associated flow rule for the calculation was established. The special module is developed for numerical simulation.(5) Under the conditions of united strength theory as the plastic rule and boundary conditions obtained by boundary-loading-extracting, the stability of the powerhouse caverns during its’excavation and supporting was analyzed.The development and distribution of plastic zones were similuated, acquire the change process of displacement was obtained.更多还原