边坡稳定分析中不平衡推力法的两种解法

不平衡推力法是我国独创的边坡稳定分析方法,在滑坡稳定分析和治理中得到广泛地应用.然而当边坡滑面为圆弧形时,不平衡推力法的精度与Bishop法相当,但是当滑面为不规则折线时安全系数与Bishop法可能相差很大,这会对工程的安全带来隐患.由于上述原因,对非圆弧形滑面最好不要单独使用不平衡推力法,而应采取多种方法进行综合分析.     

改进复合形法及其在边坡稳定分析中的应用

基本复合形法寻优考虑了复形顶点目标函数的改进,但忽略了保持复形顶点的多样性,从而有可能使算法易陷入局部极优．为此,进行了以下改进：对每个顶点构造寻优直线,即该顶点与其余顶点几何中心的连线;在该直线上寻找该顶点的改善点并替换掉该顶点构造新的复形;在构造的多个新复形中,选择多样性最强的新复形作为本次迭代产生的复形;如此迭代直至没有新的复形产生．顶点多样性采用复形相似距度量．通过对1个复杂边坡最小安全系数的搜索证明,这些改进措施是有效的．     

边坡稳定的三维极限平衡分析法

提出一种边坡稳定分析的三维极限平衡法,用其对小湾式岸坝前堆积体边坡进行稳定性分析,所得结论与离心模型试验及三维非线性有限元件计算结果基本吻合。由于该法需要较少的试验参数,适用于大面积复杂地形地质条件上的边坡稳定分析,全部计算过程可以编程进行,故有很好的应用价值。     

边坡下滑推力的计算分析

边坡的安全系数定义有两种:下滑力超载储备与强度储备的安全系数。现有工程规范中对边坡下滑推力计算方法是基于下滑力超载储备的安全系数,含义不清,而国际上能用的强度折减法,是基于强度储备的安全系数,力学意义明显,符合边坡破坏的实际情况。对比下滑推力的两种计算,规范法的计算结果随安全系数呈线性增长,比强度折减法大,导致工程不必要的浪费。     

对称破坏机制下的边坡稳定三维滑动场分析方法

针对现有边坡三维极限平衡分析方法,提出了一种对称破坏机制下的边坡稳定三维滑动场分析方法,该方法基于剩余推力法原理,采用优化控制理论求解危险滑面并进行评价.同时,结合矿山人工开挖边坡的特点,应用三维滑动场方法进行反向搜索,即在指定安全系数下计算最大允许坡角,从而实现边坡优化设计.     

随机多样复合形法及在边坡稳定分析中的应用

针对基本复合形法对任意初始复形寻优成功率较低的缺陷,规定当前复形中与其他顶点相似程度最大的顶点为被替换点,目标函数值有所改善的替换点在被替换点与其余顶点中任意几个的中心点连线上寻找,替换后构成新的复形,如此不断迭代构成了随机多样复合形法.利用随机多样复合形法以及基本复合形法对两个复杂、非均质土坡的最小安全系数进行了搜索,比较结果证明了随机多样复合形法的较强全局搜索能力.     

利用不平衡推力法分析昭山地区边坡稳定性

不平衡推力法作为一种重要的边坡稳定性分析的确定性方法,普遍应用于工程实际中.针对牵引式破坏和推移式破坏2种模式下土体条块间力的传递方式不同及相应安全系数的计算方式也存在差异的问题,引入条分法的概念,假定各条块间的相互作用力方向一致,根据这2种失稳模式下各条块间力和力矩的平衡关系,推导出相应边坡安全系数的计算公式.结合具体边坡实例,分析了这2种不同的潜在失稳模式下安全系数的差异,证实了潜在失稳模式对利用不平衡推力法评价边坡稳定性的结果影响较大.     

考虑整体力矩平衡的改进不平衡推力法

为了提高常用的剩余推力法的精度,通过引入比例因子确定条间力作用倾角,建立同时考虑力平衡和力矩平衡的联立方程组,求得边坡安全系数,并通过算例验证了其可靠性。研究表明:不平衡力矩和边坡安全系数均随着比例因子的变化而接近线性改变;相对于常规不平衡推力法而言,改进法求解安全系数时具有更高的精度和更快的收敛速度;在不考虑水平地震力时,条间力方向与条底滑面基本平行;考虑较大地震力作用时,条间力倾角变化主要集中发生在边坡后部的少数几个条块中。当比例因子为零时,改进不平衡推力法与常规不平衡推力法是一致的,故其可以视作常规法的扩展形式。     

岩质边坡稳定分析三维与二维的比较

提出岩质边坡沿软弱结构面滑移一剪切的三维稳定分析方法。在分析模型中,下滑体沿滑动面下滑,在其他的面上则产生剪切破坏。在结构面上满足莫尔库伦破坏准则,把剪切面上的摩阻力向下滑方向投影,由下滑体的力学平衡条件求解出未知力,通过迭代可以求得稳定系数。同时推导了摩阻力倾向与倾角的计算式,编制了相应的程序,并利用这个程序,研究了边坡长度、岩层与坡面夹角等因素对边坡稳定系数的影响,比较了三雏分析与二维分析的差别。     

A new double reduction method for slope stability analysis简

The core of strength reduction method （SRM） involves finding a critical strength curve that happens to make the slope globally fail and a definition of factor of safety （FOS）. A new double reduction method, including a detailed calculation procedure and a definition of FOS for slope stability was developed based on the understanding of SRM. When constructing the new definition of FOS, efforts were made to make sure that it has concise physical meanings and fully reflects the shear strength of the slope. Two examples, slopes A and B with the slope angles of 63~ and 34~ respectively, were given to verify the method presented. It is found that, for these two slopes, the FOSs from original strength reduction method are respectively 1.5% and 38% higher than those from double reduction method. It is also found that the double reduction method predicts a deeper potential slide line and a larger slide mass. These results show that on one hand, the double reduction method is comparative to the traditional methods and is reasonable, and on the other hand, the original strength reduction method may overestimate the safety of a slope. The method presented is advised to be considered as an additional option in the practical slope stability evaluations although more useful experience is required.     

容重增加法在边坡稳定性分析中的应用

通过逐步增加容重的方法使边坡达到极限平衡状态,基于D-P准则,采用关联流动法则,用非线性有限元法进行数值模拟.将坡顶水平位移随容重增加系数的变化关系曲线上位移陡然增大作为边破的破坏标准,用一个区间描述边坡稳定安全系数.该法无须事先对滑动面的位置和形状作出任何假定,能够考虑土体的材料非线性和几何非线性,有助于了解边坡的破坏机理.同时由于用一个区间描述边坡稳定安全系数,避免了数值计算中真实安全系数的丢失.算例分析表明,用容重增加法得到的安全系数与传统方法相近,并建议安全系数区间的长度取为0.03.     

土坡稳定可靠度分析

简述了可靠度分析的“ＪＣ”法,介绍了一种典型的土坡稳定分析模型的极限状态方程,编写了一套完整的计算程序,并结合算例,对该法应用中的一些问题进行了讨论     

基于强度折减法的不同坡角边坡稳定性分析

介绍了强度折减法的基本原理,在此基础上运用强度折减法分析边坡坡角对边坡稳定性的影响,运用ANSYS软件模拟不同坡角的边坡,分析计算不同坡角边坡的安全系数,通过计算得出不同坡角边坡围岩极限破坏时的折减强度参数,分析研究边坡坡角与边坡安全系数F、边坡围岩极限破坏凝聚力c’及极限破坏摩擦角‘φ’之间的关系。     

局部安全系数法中约束对土坡稳定分析的影响

为研究局部安全系数法中不同约束条件对土坡稳定分析的影响,结合两典型土坡,对局部安全系数法这一双重优化问题中的约束条件进行了分析,约束条件主要包括极大化问题中条块间法向力、剪切力、条底法向力需满足的约束以及极小化问题中可行滑动面需满足的约束条件,研究结果表明,限制条块间法向力为正,而允许条间剪切力为负条件下,局部安全系数法所得结果较为合理.     

Discontinuous flying particle swarm optimization algorithm and its application to slope stability analysis

A new version of particle swarm optimization (PSO) called discontinuous flying particle swarm optimization (DFPSO) was proposed, where not all of the particles refreshed their positions and velocities during each iteration step and the probability of each particle in refreshing its position and velocity was dependent on its objective function value. The effect of population size on the results was investigated. The results obtained by DFPSO have an average difference of 6% compared with those by PSO, whereas DFPSO consumes much less evaluations of objective function than PSO does.     

Couple analysis on strength reduction theory and rheological mechanism for slope stability

Considering the rheological properties of rock and soil body,and exploiting the merit of strength reduction technique,a theory of couple analysis is brought forward on the basis of strength reduction theory and rheological properties.Then,the concept and the calculation procedure of the safety factor are established at different time.Making use of finite element software ANSYS,the most dangerous sliding surface of the slope can be obtained through the strength reduction technique.According to the dynamic safety factor based on rheological mechanism,a good forecasting could be presented to prevent and cure the landslide.The result shows that the couple analysis reveals the process of the slope failure with the time and the important influence on the long-term stability due to the rheological parameters.     

Upper bound analysis of slope stability with nonlinear failure criterion based on strength reduction technique

Based on the upper bound limit analysis theorem and the shear strength reduction technique, the equation for expressing critical limit-equilibrium state was employed to define the safety factor of a given slope and its corresponding critical failure mechanism by means of the kinematical approach of limit analysis theory. The nonlinear shear strength parameters were treated as variable parameters and a kinematically admissible failure mechanism was considered for calculation schemes. The iterative optimization method was adopted to obtain the safety factors. Case study and comparative analysis show that solutions presented here agree with available predictions when nonlinear criterion reduces to linear criterion, and the validity of present method could be illuminated. From the numerical results, it can also be seen that nonlinear parameter m, slope foot gradient β, height of slope H, slope top gradient α and soil bulk density γ have significant effects on the safety factor of the slope.