【作者】 周江平；

【导师】 赵善锐；

【作者基本信息】 西南交通大学 ， 岩土工程， 2004， 博士

【摘要】 本论文是在深入系统地研究了土石坝抗滑稳定的可靠度理论和地基砂层的地震液化的可靠度理论基础上，结合本人承担或参加的冶勒堆石坝抗滑稳定的可靠度研究、永乐水电站厂房地基处理及砂层液化研究、紫坪铺水库淹没区213国道改线工程石门坎滑坡稳定性研究等试验、科研和施工项目的进行而完成的。土石坝的可靠度分析因涉及坝基多种土层与坝体多种材料的岩土参数的统计特征，加上所受荷载复杂，进行可靠度稳定分析难度较高。在遭遇渗流和地震等动力荷载时，坝基砂土液化判别是很复杂的，其可靠度分析难度更高。本文旨在建立坝体和坝基抗滑稳定的可靠度、地基土液化稳定的可靠度模式，解决其可靠度计算问题。主要进行以下几方面的研究工作并取得了相应成果。 岩土的物理性质和力学参数为随机变量，在母体分布拟合优度检验中存存一组数据同时通过多个概率分布模型的可能。为解决选择母体分布类型问题，可用似然比检验来进行分布择优。论文以冶勒水库土石坝为例分别对坝基土体与坝体填筑材料的物理性质和力学参数概率特征与概率分布模型进行的分析研究。对于大致均匀的土层或性质差别不大的土层，其土工参数应具有相同或相近的自相关特性，表现为有相同的自相关函数形式及相关范围。 Cornell定义的结构可靠度指标β=（μ_M）/（σ_M），β的取值依赖于特定展开点的选择。Hasofer和Lind建议根据临界破坏面而不是极限状态方程定义失效模式的可靠度指标β。Rackwitz和Fiessler提出了推广的H-L算法，考虑到变量可能为正态分布，对数正态分布和极值I型分布等分布类型，R-F算法被国际结构安全性联合会（JCSS）所推荐，又叫JC法。Monte-Carlo模拟方法的基本思想是：若已知随机变量X₁，X₂，…，X_k的概率分布，根据随机变量X₁，X₂，…，X_k的分布利用Monte-Carlo方法产生相应分布的一组随机数X₁，X₂，…，X_k，代替试验值。将这组随机数代入极限状态方程Z=（X₁，X₂，…，X_k），便可得到随机变量Z的一个样本Z₁．Z₂，…，Z_n，其中Z_j=g(X_1i，X_2i，…，X_ki)，若Z₁，Z₂，…，Z_n中有M个z＜0，则破坏概率的第V页西南交通大学博士学位研究生论文估计量、随机变量z的均值和均方差的估计量分别为弃一M‘N，户:=土丫Z‘N廿‘在估计失效概率的标准差时，可用其估计量弃来代替Pr。用Jacob‘数学变换方法将互为相关的岩土参数r、。、f转换为相互独立的随机变量，使问题简化为按独立空间计算失效概率Pf和可靠度指标p。 从材料的细观力学特性入手，到宏观的统计尺寸效应，讨论了岩土工程试验中存在不同尺寸的试样，其试验成果有明显的差异。在岩土参数取值中引入了纤维束理论解决试验的尺寸效应，用纤维束理论讨论了小尺寸、中尺寸、大尺寸试样的尺寸效应关系，通过Monte一Carlo随机抽样的模拟验证，土体强度存在尺寸效应，集团抽样方式反证了小尺寸试样强度的平均值不能代表中尺寸、大尺寸试样的强度，中尺寸和大尺寸试样的强度代表性更好。并与工程中边坡稳定性分析结合，岩土参数取值考虑尺寸效应，则土坡有一致的抗滑稳定安全系数水平。文中用一实例示范了尺寸效应如何影响边坡稳定性计算结果。 推导了简化毕肖普法的极限状态方程，对边坡稳定的可靠度以1个工程实例进行了示范，即冶勒土石坝的稳定性计算与稳定可靠性分析，以大尺寸的现场原位试验数据为基础，在合理划分样本总体的情况下，岩土体物理性质指标和力学参数作为随机变量的概率特征与概率分布模型合理，并可以得到变异系数较小的土性参数统计值。考虑随机变量间的相关性，采用Jacobi正交变换法将相关的随机变量转变为相互独立的随机变量。实例比较了常规稳定性分析与可靠度稳定分析的差异性;在抗滑稳定分析中，考虑渗透压力的计算结果更精确;对同一工况下安全系数k=1 .0时存在多个滑面，但各滑面稳定的可靠性指标 （p）不相同。 砂层地震液化的判别分为初判和复判两步，初步判别按土层的地质条件或土层剪切波速度Vs与土层的上限剪切波速度Vs:的比值进行判别。当该砂层初判为可能液化，则应进行复判。复判方法有两类:一类是依据现场试验的静力触探强度和标准贯入试验的击数方法;二类是依据室内实验的三轴动强度的动剪西南交通大学博士学位研究生论文第Vl页应力比法。对砂土液化评判的方法进行了系统总结，并以永乐水电站为例，用砂土液化的综合判别指导了永乐水电站厂房地基处理。提出了旋喷桩施工过程中高压水气产生的上体液化与基坑内的渗透液化的祸合问题，分析了液化的祸合的机理，提出了防止液化的祸合的条件为:保持基坑内的水力坡降今义（浮容重厂，水容重入，）。推导了基于动力三轴试验的动剪应力比的液化极限状态方程。指出无量纲动强度:刹对液化判别的机理，编制了液化可靠度计算程序，在Monte一Carlo随机模拟方法中，当抽样量MM达到1火1 04一1又l护次时，计算结果收敛。以民治水电站闸坝地基液化为例进行了液化的可靠水准I与水准H的分析:利用标准贯入试验液化判别，考虑到了土体的随机性，引进了具有概率意义的液化指数，计算的场地液化指数和?更多还原

【Abstract】 The paper is based on researching reliability theory both the stability of earth and rock-filled dam and the liquefaction of sand foundation. The paper is finished combining with research projects and building projects, including reliability stability of Yele Earth and Rock-filled Dam, improvement research of sand foundation of Yongle Hydroelectric Power Station and stability investigation of Shimenkan slope on the National Road 213 in flood area in Zipingpu Reservoir. The reliability research of tall earth and rock-filled dam is tough task, because the analysis needs statistical data from many kinds of soil of the dam foundation and natural building materials. Especially when the dam encounter earthquake, the reliability analysis is more difficult. The liquefaction judge of sand foundation of dams is difficult problem. The reliability analysis of the problem is more difficult when the dam encounter earthquake plus seepage. The paper aims at building a series of model of reliability analysis, solving the computing of reliability both the stability of slope and the liquefaction of sand foundation. The following aspects of research work are done, and the research achievements are gained.Data of both the physical feature and the strength in soil and rock mass, which are used as foundation of the dam and natural building materials of dam, is random variable. The paper taken YeLe earth and rock-filled dam as an example, and the probability distribution models of the data is checked, and the statistical character of the data is analyzed.The paper have introduced three methods of reliability analysis: 1) Using First Order Second Moment (JC method) recommended by JCSS organization and national codes computes both failure probability and reliability index for independent variable; 2) Using Monte-Carlo random simulation calculates both failure probability and reliability index for independent variable; 3) Using Jacobi transfer method changes dependent variable into independent variable.Three scale type of soil strength tests; small, middle and big size is extensively existed in engineering practice. The data from different project have indicated the statistical scale effect of soil strength. In order to solve the dimension size effect inxperiment, the facsimile theory is adopted in determination the rock parameters. It is also used in discussing the size effect relationship of small, medium and large size samples. The results of research express that the strength of medium and large size samples have more suitable representative. The calculation results of an example explain how the size effect to influence the slope stability.The limit function of Bishop’s Simplified method is deduced. The paper has taken stability analyses of practice engineering as an example. The example is Yele Earth and Rock-filled Dam. The coefficient of variation of soil strength is less, when the data from in-site tests with big size is reasonably divided into statistical groups. The model of probability distribution was checked. Jacobi transfer method is used to change dependant variable into independent. The results computed by the engineering example show that the deterministic stability method is consistent with reliability stability method. The seepage must be calculated in both the deterministic stability method and reliability stability method. The critical circles, factor of safety equate to 1.00, is more than one, but index of reliability ( ) in the critical circles is not equal.The liquefaction evaluating process of sand foundation for earthquake includes preliminary judge and precis judge. The methods of liquefaction evaluation are systematically summarized. The paper has taken Yongle Hydroelectric Power Station as an example, the results of liquefaction analysis aid to improve foundation of the powerhouse. Liquefaction couple from the seepage liquefaction of groundwater in the foundation pit and the liquefaction for jetting grounded pile with high-pressure gasified water was discovered during foundation pit excavated. The mechanism of liq更多还原