应用强度折减有限元法分析土坡稳定的适应性

为深入研究土体采用的本构模型以及安全系数的控制标准．讨论了土体采用邓肯E—B模型和理想弹塑性的广义米塞斯模型时,强度折减有限元法分析土坡稳定的适应性．发现邓肯E—B模型的适应性较差,土坡内应变发展不均匀,不能形成明显的剪切带．而弹塑性的广义米塞斯模型则形成剪切带,剪切带两侧土体具有明显的相对滑移趋势．因此,弹塑性模型更适合干强度折减有限元法分析土坡稳定性．     

等厚抛石护坡时土坡临界坡度的判定

本文系根据Fellenius的土坡稳定理论分析的基本假设为基础,即假设土坡滑动曲面为圆弧面,并简化为平面问题,用静力平衡方法,按照土坡的主要特征条件,引入土坡临界坡度的概念,推求等厚抛石护坡适用与否的简易判别计算式。     

人工土坡非稳定渗流引起滑坡的分析及整治

通过研究非稳定渗流的渗透压力计算方法,提出了改进的计算方法,编制了土坡滑动稳定分析 Ｂ Ｓ Ｔ Ａ 计算程序．通过实际土坝上游滑坡事故实例分析,说明改进的方法能反映实际情况,可用于工程实际的土坡稳定校核设计和滑坡分析．     

强度折减有限元法分析成层土坡的适用性

通过实例讨论了强度折减有限元法分析成层土坡稳定的可行性,分析表明对于均质土坡,强度折减得到的安全系数在工程允许的范围之内,但折减后的应力场发生了变化,不能用于分析原土坡的稳定性;对于多层土坡,通过简单折减土的强度指标c,tanφ,不能得到正确的应力场,也不能得到土坡的安全系数.     

基于蒙特卡罗法的土坡稳定可靠度分析

采用可靠度分析的蒙特卡罗法,对土坡稳定可靠度进行了分析,并以工程事例为例,讨论了计算模型以及土性参数的均值和变异系数对可靠指标的不同影响,并对可靠指标和安全系数度量土坡稳定的合理性进行了一定的比较。     

强度折减有限元法分析成层土坡的适用性

通过实例讨论了强度折减有限元法分析成层土坡稳定的可行性,分析表明:对于均质土坡,强度折减得到的安全系数在工程允许的范围之内,但折减后的应力场发生了变化,不能用于分析原土坡的稳定性;对于多层土坡,通过简单折减土的强度指标c,tanφ,不能得到正确的应力场,也不能得到土坡的安全系数。     

三峡升船机结构简化力学模型

利用三维有限元方法计算的结构动力特性和简化结构的动力特性相等的原则修正升船机结构简化力学模型，并确定了等效的升船机简化结构模型和系统参数．分析和计算表明，建立的简化力学模型较好地反映了升船结构的动力特性和地震反应，建立的简化力学模型可用于升船机顶层厂房地震鞭梢效应的智能控制设计。     

附着式塔式起重机弹性二阶分析

讨论了附着式塔式起重机的一层、两层附着两种情况的弹性二阶受力性能,以FZQ2000Z型塔式起重机为研究对象，提出了相应的简化计算模型，对该简化模型进行了二阶效应分析并与有限元软件分析计算的结果进行了比较，计算结果最大相差3．9％．分析结果表明，所提出的简化模型能够反映实际塔式起重机的弹性二阶特征，同时塔式起重机当吊重较大时，二阶受力特点是明显的．     

阻滑桩加固土坡的极限设计方法

对日本学者Tomio基于塑性变形理论法计算滑面以上部分桩的侧向力计算公式的适用性进行了简单讨论,应用该公式计算桩的阻滑力,将简化Bishop法推广到用阻滑桩加固土坡的情况,同时假设实际发挥的阻滑力与土坡的安全系数有关,该方法能够同时反映因设置阻滑桩而引起土坡安全系数和最危险滑面位置的变化;最后,以一需要加固的码头岸坡为例,采用按上述方法编制的程序讨论了土坡中利用单排阻滑桩进行加固时桩径距比、布桩位置对码头岸坡安全系数的影响,提出了土坡中考虑桩土相互作用的阻滑桩设计方法的具体步骤。     

一种新并联主手的灵巧度分析

建立了基于Delta和3-RRR复合结构的双并联式主手平动与转动独立的运动学模型,并推导出各自的雅可比矩阵,给出了局部灵巧度和全局灵巧度的计算方法．在计算过程中,引入了MonteCarlo方法使计算过程简化,效率提高．给出了特定构型下的机构灵巧度分析结果,验证了上述方法的有效性,灵巧度的分析结果可直接用于主手的优化尺度综合．     

西安白鹿塬北缘黄土边坡稳定的可靠度分析

在西安白鹿塬北缘实测了14个黄土自然边坡断面,建立了地质模型,通过采样测试并收集已有的测试资料,获得了各时代黄土地层的物理力学参数,将Morgenstern-Price法稳定性计算公式作为极限状态方程,分别采用Monte-Carlo法和Duncan法进行了边坡稳定的可靠度分析。结果表明:采用Monte-Carlo法和Duncan法得到的14个边坡稳定系数分别为1.11～1.41和1.09～1.33,显示这些边坡处于基本稳定—稳定状态; 采用上述两种方法得到的边坡可靠指标分别为0.56～1.79和0.39～1.60,得到的失效概率分别为3.4%～29.0%和5.5%～34.8%,并且共有75%的边坡失效概率大于10%,失效可能性较大。统计结果表明:白鹿塬区边坡的坡高和坡度存在负相关性。低而陡的边坡潜在最危险滑面剪出口较高,失效概率较小; 坡高达到50 m及以上时,边坡高而缓,剪出口较低,失效概率较大,其中河流下切深,有N₂泥岩出露的极高边坡,稳定性最差。Duncan法求解的稳定系数略小于Monte-Carlo法求得的结果,而前者求解的失效概率略大于后者,两种方法计算结果较为接近。由于Duncan法理论简单,计算量小,更宜于在实际工程中应用。     

基于ABAQUS的边坡失稳综合判据法

在分析有限元计算不收敛、坡体位移突变和潜在滑移面塑性区贯通这3种边坡失稳判据优缺点的基础上,提出边坡失稳的综合判据法,即先进行小变形有限元计算,以计算不收敛为边坡失稳判据,后进行大变形有限元计算,以位移突变为判据。采用综合判据法、运用ABAQUS有限元软件对一个标准算例和一个工程实例进行边坡稳定性分析,并与常用的简化Bishop法进行比较,二者所得安全系数接近,证明了边坡失稳综合判据法的合理可行。     

坡面冲刷的临界坡度的计算分析

分析了土质边坡临界坡度理论．通过坡面流拖曳力法、坡面流量法和坡面流挟砂力法对临界坡度进行了详细地分析计算,得出了坡面冲刷临界坡度范围,并由此分析得出目前公路边坡冲刷问题严重的一个原因就是由静力稳定性设计方法计算得到的安全坡度与临界坡度十分接近．     

Intelligent prediction of slope stability based on visual exploratory data analysis of 77 in situ cases

Slope stability prediction research is a complex non-linear system problem. In carrying out slope stability prediction work, it often encounters low accuracy of prediction models and blind data preprocessing.Based on 77 field cases, 5 quantitative indicators are selected to improve the accuracy of prediction models for slope stability. These indicators include slope angle, slope height, internal friction angle, cohesion and unit weight of rock and soil. Potential data aggregation in the predicti...     

Application of fuzzy optimal selection of similar slopes to the evaluation of slope stability

The numerical calculation method is widely used in the evaluation of slope stability,but it cannot take the randomness and fuzziness into account that exist in rock and soil engineering objectively.The fuzzy optimization theory is thus introduced to the evaluation of slope stability by this paper and a method of fuzzy optimal selection of similar slopes is put forward to analyze slope stability.By comparing the relative membership degrees that the evaluated object sample of slope is similar to the source samples of which the stabilities are detected clearly,the source sample with the maximal relative membership degree will be chosen as the best similar one to the object sample,and the stability of the object sample can be evaluated by that of the best similar source sample.In the process many uncertain influential factors are considered and characteristics and knowledge of the source samples are obtained.The practical calculation indicates that it can achieve good results to evaluate slope stability by using this method.     

Limit equilibrium stability analysis of slopes under external loads

Two calculation modes for the effect of external load on slope stability, i.e., mode I in which the external load is thought to act on slope surface, and mode II in which the external load is thought to act on slip surface along the force action line, were considered. Meanwhile, four basic distribution patterns of external load were used, of which complex external loads could be composed. In analysis process, several limit equilibrium methods, such as Swedish method, simplified Bishop method, simplified Janbu method, Spencer method, Morgenstern-Price(M-P) method, Sarma method, and unbalanced thrust method, were also adopted to contrast their differences in slope stability under the external load. According to parametric analysis, some conclusions can be obtained as follows:(1) The external load, with the large magnitude, small inclination angle, and acting position close to the slope toe,has more positive effect on slope stability;(2) The results calculated using modes I and II of external load are similar, indicating that the calculation mode of external load has little influence on slope stability;(3) If different patterns of external loads are equivalent to each other, their slope stability under these external loads are the same, and if not, the external load leads to the better slope stability,as action position of the resultant force for external load is closer to the lower sliding point of slip surface.     

Limit equilibrium method for slope stability based on assumed stress on slip surface

In the limit equilibrium framework, two- and three-dimensional slope stabilities can be solved according to the overall force and moment equilibrium conditions of a sliding body. In this work, based on Mohr-Coulomb(M-C) strength criterion and the initial normal stress without considering the inter-slice(or inter-column) forces, the normal and shear stresses on the slip surface are assumed using some dimensionless variables, and these variables have the same numbers with the force and moment equilibrium equations of a sliding body to establish easily the linear equation groups for solving them. After these variables are determined, the normal stresses, shear stresses, and slope safety factor are also obtained using the stresses assumptions and M-C strength criterion. In the case of a three-dimensional slope stability analysis, three calculation methods, namely, a non-strict method, quasi-strict method, and strict method, can be obtained by satisfying different force and moment equilibrium conditions. Results of the comparison in the classic two- and three-dimensional slope examples show that the slope safety factors calculated using the current method and the other limit equilibrium methods are approximately equal to each other, indicating the feasibility of the current method; further, the following conclusions are obtained: 1) The current method better amends the initial normal and shear stresses acting on the slip surface, and has the identical results with using simplified Bishop method, Spencer method, and Morgenstern-Price(M-P) method; however, the stress curve of the current method is smoother than that obtained using the three abovementioned methods. 2) The current method is suitable for analyzing the two- and three-dimensional slope stability. 3) In the three-dimensional asymmetric sliding body, the non-strict method yields safer solutions, and the results of the quasi-strict method are relatively reasonable and close to those of the strict method, indicating that the quasi-strict method can be used to obtain a reliable slope safety factor.     

不同失稳判据下边坡稳定性的规律性

以塑性区贯通、位移增量突变、计算不收敛3种边坡失稳判据为依据,采用强度折减有限元法和重度增加有限元法对简单边坡进行了分析。结果表明：以边坡潜在滑动面上某点位移增量突变作为边坡失稳判据是准确的;对于不同土体强度参数下,以位移增量关系曲线突变为判据得到的边坡的安全系数较另外两种方法稳定;对应于塑性区贯通、位移增量曲线突变和计算不收敛的3种判据,边坡潜在滑动面依次向深层发展,边坡的安全系数依次增加。     

边坡工程稳定性弹—粘—塑性有限元分析中随机—模糊可靠度算法

岩体的基本特性是其力学性质的随机性和模湖性。对边坡工程进行稳定性分析时,必须同时考虑其随机和模糊性。本文给出了弹—粘—塑性有限元分析中计算边坡工程随机——模糊可靠度的理论方法,导出了相应的公式,利用自编的程序以算例验证了这种方法的正确可行性。     

基于M-P水平条分法的加筋土坡稳定性计算方法

土坡水平加筋是一种使用广泛的加筋方式,但常用的垂直条分法无法有效地分析水平筋材的效果。研究采用Morgenstern-Price水平条分法分析新型加筋土坡的稳定性,根据条块力与力矩平衡,分别推导出安全系数Fs和比例系数λ的表达式,迭代得到计算结果。通过与水平条分简布法和水平瑞典法的算例对比分析,证明方法具有可行性,为边坡工程加筋技术提供理论参考。