【作者】 刘艳章；

【导师】 葛修润；

【作者基本信息】 中国科学院研究生院（武汉岩土力学研究所） ， 工程力学， 2007， 博士

【摘要】 边坡与坝基抗滑稳定分析一直都是岩土力学的一个经典研究领域,研究成果很多,根据各种不同的假定形成了各类不同的分析方法,但现有方法的分析基础,即采用抗滑力代数和与下滑力代数和之比定义安全系数,在大部分工程条件下缺乏必要的物理意义。工程中真正需要的是既有明确的物理意义和坚实的理论基础,又简单实用而能较好地服务于工程实际需要的边坡与坝基抗滑稳定分析方法,本文在此方面做了一些尝试性的研究与探讨工作。主要研究内容及结论如下:(1)阐明了边坡与坝基抗滑稳定分析的研究意义,简要回顾和评述了现有边坡与坝基抗滑稳定分析法和考虑爆破地震影响的边坡稳定分析方法,针对现有分析方法中存在的问题,提出了本文的主要研究内容。(2)对现有边坡与坝基抗滑稳定分析中两类安全系数——超载安全系数与强度折减安全系数的定义进行了讨论。两类安全系数的定义式中,沿滑动面对力简单叠加的力学意义不明确;强度折减法通常对岩土体的两个强度参数按同一比例进行折减与岩土体的真实强度特性有差别;沿不同方向增大荷载所计算的超载安全系数之间也没有合理的可比性,因为总荷载的大小和方向都发生了变化;超载法和强度折减法计算安全系数所依赖的应力分布是人为假定条件下得到的,而不是真实荷载与物理条件下的应力分布;因此,这两类安全系数定义的物理或力学意义值得商榷。(3)依据滑动的矢量特征,提出了边坡与坝基抗滑稳定的矢量和分析法,定义了矢量和法安全系数。在运用有限元分析得到应力分布的基础上,根据摩擦理论和滑动面的受力情况确定边坡与坝基的整体滑动趋势方向,以此方向作为计算方向,将矢量和法安全系数定义为,滑动面上各处抗滑力投影的代数和与滑动力在计算方向上投影的代数和之比,此安全系数定义的物理力学意义明确,且安全系数通过一个显示方程求解,计算过程简单,便于工程应用。(4)通过理论分析表明,在圆弧型和单直线滑动面的特殊情况下,将滑体视为刚体时,矢量和法安全系数的定义式与传统的刚体极限平衡分析法中依据滑动面上的抗滑力与滑动力代数和之比定义的安全系数的定义式等价。(5)运用边坡与坝基抗滑稳定的矢量和分析法对几道简单的边坡算例进行了分析。计算结果表明:本方法计算的矢量和法安全系数,在单直线与圆弧滑动面情况下与传统的极限平衡法依据力的代数和计算的结果一致,在其它情况下有一定的差别,且各算例的矢量和法安全系数都比有限元强度折减法的安全系数要低。(6)运用边坡与坝基抗滑稳定的矢量和分析法,计算了三峡工程左厂3#坝段坝基的深层抗滑稳定的矢量和法安全系数。计算结果表明:滑移路径越陡,其矢量和法安全系数越小;凡包含ABCFH段结构面的潜在滑移路径的矢量和法安全系数值都较低,这与已有的有限元强度折减法的定性分析成果相吻合。通过在实际工程中的应用,验证了边坡与坝基抗滑稳定分析方法的可行性与实用性。(7)在分析天然地震与爆破地震对边坡动力影响差异的基础上,提出了考虑爆破地震动荷载影响的边坡稳定矢量和分析法。该分析法将时程分析法与拟静力法相结合,运用有限元法分析在爆破振动惯性力荷载与静荷载共同作用下坡体内各点各时刻的应力分布,根据边坡与坝基抗滑稳定的矢量和分析法计算边坡的安全系数;该分析法较好地体现了爆破振动对边坡动态影响的实际特点,求解的矢量和法安全系数具有更明确的物理力学意义,且求解过程简单。(8)应用考虑爆破地震动荷载的边坡稳定矢量和分析法,求解了黄麦岭磷矿底板最终边帮在不同工况条件下的矢量和法安全系数。计算表明,就黄麦岭磷矿的单次爆破而言,爆破振动下的矢量和法安全系数与静载时相比,降低率在10%以内,现有生产爆破振动影响下矢量和法安全系数的最小值为1.119,与该边坡基本稳定的实际情况相符;而拟静力极限平衡法计算的安全系数只有0.669,与工程实际相差甚远。更多还原

【Abstract】 Stability analysis of slope and dam foundation against sliding is a classic research field in rock and soil mechanics. Although there are a lot of research results in this field, the analytical basis of commonly used methods, defining their safety factors with the ratio of the algebraic sum of forces against sliding to that of forces driving sliding, lacks physical meaning under most engineering conditions. the stability analysis method meeting engineering needs is the method that is of clear physical significance and solid theoretical foundation, as well as simple and practicable. This thesis attempts to do some studies and discussions on this issue. The main studies and conclusions of this thesis are as follows.(1) State the significance of stability analyses of slope and dam foundation against sliding. The stability analysis methods, available in the literature, are reviewed. Aiming at the problems of common analytical methods of stability analyses, the main studies in this thesis are presented.(2) Discuss the definitions of two kinds of safety factors, the overload safety factor and the strength reduction safety factor, in common analytical methods of stability analyses. The force integral of the two safety factor definitions along the slip surface is ambiguous in mechanics. It is different from the real strength properties of rock and soil masses reducing the two strength parameters with a same coefficient as applying the strength reduction method. The overload safety factors calculated by overloading at different directions are out of comparability. The stress state with which the safety factors of the two definitions are calculated is obtained in terms of arbitrary assumptions. Thus the significance of the two safety factor definitions is questionable.(3) Put forward the vector sum analysis method of slope and dam foundation stability against sliding (VAM), and define the vector sum method safety factor (VF), based on the vector characteristic of the sliding motion. After the stress distribution calculated with the finite element analysis, on the basis of the friction theory and the slip surface stress, the direction of the sliding tendency of slope and dam foundation as a whole can be determined. Taking the direction as the calculating direction, the VF is defined as the ratio of the algebraic sum of the projections of anti-sliding forces to that of sliding forces along the slip surface at the calculating direction. The significance of the VF is clear in physics. The calculating process of the VF is simple and that facilitates the application of this analysis method in engineering. (4) Theoretical analysis shows: under the special condition of the circular or single line slip surface, the formula of VF and that of the safety factor defined with the ratio of the algebraic sum of anti-sliding forces to that of sliding forces in rigid body limit equilibrium methods are equivalent, as taking the slope as the rigid body sliding.(5) Apply the VAM to analyzing the stability of several simple slope cases. The results indicate: the calculated values of the safety factors applying VAM are close to that applying the limit equilibrium method under the circular slip surface or the single line surface condition, but there is some difference between them under other slip surface conditions, and the value of each case’s VF is less than that of the strength reduction method of FEM.(6) Apply the VAM to calculating the VF of the deep sliding stability of 3# dam foundation of the left power house of the Three Gorges Project. The results show: the more steep and deep the potential slip surface is, the less the VF value is; the VF value of the potential slip surface that contains joints ABCFH is less than that of others, and it is coincident with the qualitative analysis results with finite element strength reduction method available in literature. The application of the VAM to the practical engineering verifies its feasibility and practicability.(7) Propose the vector sum analysis method of the slope stability taking the dynamic loads induced by blasting seism into account (BVAM), based on analyzing the dynamic effect differences between the natural seism and the blasting seism. The BVAM calculates the VF with VAM, combining the time history method and the pseudo-static method, and analyzing the state stress inside the slope at any point and at any time by FEM with the coaction of inertia forces due to blasting vibration and static loads on the slope. The BVAM well reflects the time history characteristic of the slope under blasting vibration.(8) Solve the VF of the bottom final wall slope of Huangmailing Phosphrite Mine with the BVAM on different work conditions. The results show: in terms of an individual blasting, the VF influenced by the blasting vibration decreases within 10 percent compared with that of the static loads; that the minimum of the VF under the blasting conditions of the Mine is 1.119 is coincident with the real state of the slope that the slope is generally stable now; but that the safety factor value calculated with the pseudo-static limit equilibrium method is merely 0.669 is too far away from the real state of the slope.更多还原