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1.
基于极限分析上限定理,采用拟动力法研究了地震效应下非均质土坡的三维稳定性,并通过重度加大法（GIM）推导出边坡安全系数的显式表达式。此外,采用遗传算法进行优化,将所得结果进行对比验证,详细分析了地震条件下相关参数对边坡稳定性的影响。分析结果表明：边坡高度一定时,宽高比、边坡倾角的增大以及土体内摩擦角、非均质系数的减小均会造成安全系数的降低;拟静力法获得的结果相比于拟动力法较大,两种方法结果的差值会随着水平地震系数、有效内摩擦角的增大而增大,随着边坡倾角的增大而减小;土体放大系数的增大会导致安全系数减小,而地震波周期及波速的变化几乎对安全系数没有影响;滑动面轨迹受水平地震系数的影响较大,而受非均质系数的影响相对较小。 相似文献
2.
Earthquake effects are commonly considered in the stability analysis of rock slopes and other earth structures. The standard approach is often based on the conventional limit equilibrium method using equivalent Mohr–Coulomb strength parameters (c and ?) in a slip circle slope stability analysis. The purpose of this paper is to apply the finite element upper and lower bound techniques to this problem with the aim of providing seismic stability charts for rock slopes. Within the limit analysis framework, the pseudo-static method is employed by assuming a range of the seismic coefficients. Based on the latest version of Hoek–Brown failure criterion, seismic rock slope stability charts have been produced. These chart solutions bound the true stability numbers within ±9% or better and are suited to isotropic and homogeneous intact rock or heavily jointed rock masses. A comparison of the stability numbers obtained by bounding methods and the limit equilibrium method has been performed where the later was found to predict unconservative factors of safety for steeper slopes. It was also observed that the stability numbers may increase depending on the material parameters in the Hoek–Brown model. This phenomenon has been further investigated in the paper. 相似文献
3.
填筑和开挖边坡的稳定性分析 总被引：1，自引：0，他引：1
在有限元应力应变分析的基础上,采用以剪应力定义的安全系数和模式搜索的方法确定边坡的安全系数及最危险滑动面。在平面应变条件下,对土层均质的填筑和开挖边坡的稳定性进行了较为全面的研究,并同天然边坡的安全系数和破坏面进行比较,计算结果表明,这3类边坡滑动面的形状基本一致,天然边坡安全系数要高于填筑和开挖边坡;同时比较了采用有限元稳定评价方法和采用极限平衡方法计算结果的差别;最后分析研究了计算参数变化对填筑和开挖边坡稳定性的影响。 相似文献
4.
基于MPGA的复杂应力状态边坡稳定性分析 总被引：1，自引：0，他引：1
极限平衡法在边坡稳定性分析中处于主导地位,该算法通常建立在一定的假设之上,没有考虑边坡土体的非线性应力-应变关系,不能用于未达到极限状态以及加固后边坡的稳定性分析。为了解决以上问题,将有限元计算与多种群遗传算法（MPGA）相结合,建立一种基于MPGA的复杂应力状态边坡稳定性分析通用模型,通过数值应力场求解安全系数,并为多种群遗传算法构建适应度函数;再利用多种群遗传算法为安全系数的计算提供滑移面。为了保证分析的高效、合理,根据滑移面发展趋势,动态产生初始滑移面,并增加一个滑移面约束条件。最后,通过均质边坡和软弱夹层边坡两个典型算例分析验证了该方法的合理性;通过分析土钉加固的软弱夹层边坡,证明了该方法可用于加固等复杂应力状态边坡的稳定性分析。 相似文献
5.
Stability investigation of hill cut soil slopes along National highway 222 at Malshej Ghat,Maharashtra 总被引：2，自引：0，他引：2
L. K. Sharma Ravi Kumar Umrao Rajesh Singh M. Ahmad T. N. Singh 《Journal of the Geological Society of India》2017,89(2):165-174
The section of about 12 km of National highway 222 passing through the Malshej Ghat experience frequent slope failure due to complex geological condition, heavy rainfall and slope geometry. The area is part of Western Ghat Deccan trap and slope masses are made of basalt and its weathered crust (debris/soil). The soil slope failure problem mainly occur in rainy seasons due to induced pore water pressure and reduced strength of the slope mass. The present study has been carried out to investigate the slope forming material and assess the stability of soil slopes by numerical approach. For the identification of the vulnerable zones, field study has been carried out and five vulnerable soil slopes identified namely MGS1, MGS2, MGS3, MGS4 and MGS5 on the basis of degree of weathering and slope geometry. The laboratory experiments were carried out to determine the strength properties of the geomaterials. All the input variables acquired from the field and laboratory experiments have been used for numerical simulation, which was performed with the help of limit equilibrium method (LEM) and finite element method (FEM). Numerical analysis provides understanding of the slope behaviour and illustrates that MGS1 and MGS3 are stable slopes, MGS2 and MGS4 are critically stable, whereas, slope MGS5 is unstable. This study recommend the protection of soil slopes and suggest that more detailed investigation is required for long term remedial measures to prevent risk of damage in Malshej Ghat. 相似文献
6.
针对南海荔湾3-1气田管线穿过的海底峡谷区6个典型斜坡剖面,分别采用有限元强度折减法和极限平衡法开展斜坡稳定性分析,模型考虑了土层强度随深度的变化。计算结果对比表明,有限元强度折减法与极限平衡法分析结果一致,其中与Spencer法结果最接近,稳定系数相对误差小于3.5%。重力作用下各斜坡基本处于相对稳定状态,峡谷中下部土强度较低且坡度较高的局部区域接近临界状态,峡谷头部因坡度相对较小且土体强度相对较大,其斜坡稳定系数相对较高。地震水平加速度能够明显降低该区斜坡的稳定系数,且随着加速度值的增大滑动深度逐渐变大。当水平加速度达到0.2g时峡谷中下部区域大部分会发生滑动。海底地形坡度和土层强度是影响峡谷区斜坡稳定性的主要因素,且稳定系数与滑动面对局部坡度和强度分布较为敏感,合理的稳定性评价依赖于精确的地形数据与土层力学参数。 相似文献
7.
Te Xiao Zi-Jun Cao Xiao-Song Tang 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2017,11(1):146-159
ABSTRACTA simplified reliability analysis method is proposed for efficient full probabilistic design of soil slopes in spatially variable soils. The soil slope is viewed as a series system comprised of numerous potential slip surfaces and the spatial variability of soil properties is modelled by the spatial averaging technique along potential slip surfaces. The proposed approach not only provides sufficiently accurate reliability estimates of slope stability, but also significantly improves the computational efficiency of soil slope design in comparison with simulation-based full probabilistic design. It is found that the spatial variability has considerable effects on the optimal slope design. 相似文献
8.
极限分析上限方法在海底斜坡稳定性评价中受到了广泛关注,但已有成果未考虑地震荷载以及多土层海底斜坡可能出现的局部破坏机制。基于上限定理,推导了拟静力水平地震条件下多土层海底斜坡外力功率与内能耗散率平衡方程;结合强度折减技术和最优化方法,求解了海底斜坡整体和局部地震稳定性安全系数,并实现了多土层海底斜坡的局部滑动面搜索;通过典型算例分析,验证了本文方法的有效性。在此基础上,探讨了不同水平地震条件下两种组合土层海底斜坡的整体和局部稳定性,通过与数值解对比,其结果可以较准确地评价海底斜坡稳定性并有效预测滑移面位置。最后,将极限分析上限方法应用于一海底斜坡工程实例。 相似文献
9.
Rock slopes with planar joints or weak structural planes are vulnerable in nature, especially suffering from the natural hazards, instabilities of slopes are more prone to occur. Therefore, concerning to the influence of earthquakes, this paper performs a new procedure to evaluate slope stability in a geomaterial governed by Hoek–Brown strength criterion. A rotational failure mechanism determined by 21 dependent angle variables is introduced to respect the Hoek–Brown strength criterion. The earthquake load is characterized by a modified pseudo-dynamic method that does not violate the zero boundary condition and considers the damping properties of geomaterials. A slice approach is adopted to calculate the earthquake-induced inertial force work rate. The stability number of rock slope is considered to measure the safety. The stability number is formulated as a classical optimization problem controlled by 21 dependent angle variables and a time variable which need to be optimized by the genetic algorithm toolbox. Comparisons with the literature are made to prove rationality and accuracy of the proposed procedure. Parametric study is carried out to reveal the influence of dynamic properties. For engineering application, stability charts are provided for a quick assessment of slope safety.
相似文献10.
11.
LU Kun-lin,ZHU Da-yong,YANG Yang
均质边坡准三维安全系数实用计算曲线 总被引：1，自引：0，他引：1
针对三维极限平衡法计算边坡安全系数存在着分析过程繁琐、较难普及推广等诸多不足,建立了一套实用的三维边坡安全系数计算曲线。假设三维滑面为中间圆柱和两端为部分球面的组合滑面,采用基于滑面正应力修正的极限平衡分析方法,计算36 864个均质边坡,根据计算结果绘制该套曲线。依据该套曲线可以得到,（1）根据已知边坡体的相关指标快速获得三维安全系数,能够得到较二维分析方法更准确、更客观的稳定性评价;（2）根据实际坡体的稳定状况反分析获得滑面土体强度参数,有效地克服二维反分析得到滑面土体强度参数偏高的弊端。研究成果可为均质边坡三维稳定性初步评价提供简单、实用的参考依据。 相似文献
12.
波浪和地震等动力荷载容易引起斜坡海床失稳,进而引发海底滑坡,危及港口码头安全和海洋工程建设。本文以曹妃甸港南部深槽处海底斜坡为研究对象,考虑真实波浪荷载和地震荷载,采用有限元法和极限平衡法相结合的研究手段对海底斜坡的动态稳定性进行了定量化计算,探讨了动力效应对特殊环境下海底斜坡稳定性的影响机制。结果表明: (1)极端波浪荷载和地震动力荷载对海底斜坡稳定性影响很大,重现期为50a的波浪荷载和峰值加速度为0.15 g的地震动力荷载将引发海底斜坡失稳,且地震荷载将诱发海底斜坡产生较大位移; (2)动力效应会引发海床侵蚀和岩土体强度弱化,进而降低斜坡安全系数,这是稳定性分析中不可忽略的重要因素。 相似文献
13.
在禁忌搜索和极限平衡分析的基础上,提出了全局确定边坡最小安全系数的禁忌搜索方法,并建立了响应的模型;该方法是一种启发式的全局搜索方法,可以搜索出全局最小安全系数,同时还能确定出与之对应的最危险滑动面。将该方法应用于不同几何形状和土层信息的边坡稳定分析中,结果表明,提出的方法能够避免局部最小解,并能搜索到全局最小安全系数。 相似文献
14.
One of the most applicable geotechnical structures whose analysis is carried out through iterative procedures is the reinforced soil slope. In this regard, the most successful method for the reinforced slope analysis through numerical methods is the finite element method whose updating mesh may result in some difficulties. In this study, the Natural Element Method (NEM), which is a mesh-free method, in conjunction with conventional limit equilibrium is implemented to find the slip surface in the reinforced slopes. Results demonstrate the convergence and preciseness of the present method in comparison with the other numerical methods and conventional limit equilibrium method. 相似文献
15.
修正有限元强度折减法与失稳判据在边坡稳定分析中的应用 总被引：1，自引：0，他引：1
现有的有限元强度折减法用于边坡稳定性分析,在土体变形特性的认识和失稳判据上有缺陷。基于土体的应力-应变曲线和邓肯-张非线性弹性模型进行有限元强度折减法计算分析,在现有方法仅对强度参数--黏聚力c和内摩擦角φ进行折减的基础上,提出了切线弹性模量Et的折减算法,更全面地体现折减的内涵;提出了以潜在滑动区域的能量积分变化作为判据,根据能量积分与折减系数关系曲线的特征,将其拟合成两段直线,以其交点所对应的折减系数作为边坡的安全系数。比较分析了修正Duncan有限元强度折减法、失稳判据与文献的计算结果,同时分析了边坡滑动区能量积分计算范围对结果的影响,并用于南水北调东线实际工程计算分析。结果表明：修正Duncan有限元强度折减法能较全面考虑土体的变形和强度特性,新的边坡滑动失稳判据可行且具有较好的计算稳定性,能保证工程建设的安全。 相似文献
16.
复杂边坡稳定性问题一直是岩土工程界重点研究的问题之一,提高复杂边坡安全系数的方法有很多,其中采用抗滑桩支护是常用手段之一。以安徽省某高速公路复杂边坡为研究对象,采用套孔应力解除法对该边坡岩土体进行了地应力测试,以测试结果作为有限元分析的边界条件,分别对该边坡加固前和采用抗滑桩加固后两种工况进行数值分析,得到有代表性的有限元分析结果;并对有限元的计算出位移结果和实测位移进行了对比。分析表明,未采用抗滑桩支护的边坡,会产生局部应力过分集中、整体变形和水平向位移较大、塑性区贯通等不利于边坡稳定的危险状况。采用了抗滑桩支护后,贯通的塑性区消失,边坡变形和位移减少,应力分布趋于均匀,安全系数大幅度提高。有限元计算出的位移结果和实测位移十分接近,匹合度较好,从而说明了有限元分析手段的可靠性。 相似文献
17.
地震效应和坡顶超载对均质土坡稳定性影响的拟静力分析 总被引：3，自引：0，他引：3
基于强度折减技术和极限分析上限定理,假定机动容许的速度场破坏面,考虑坡顶超载、水平和竖向地震效应影响推导了边坡稳定性安全系数的计算表达式。采用序列二次规划迭代方法（和内点迭代方法）对边坡安全系数目标函数进行能量耗散最小化意义上的优化计算,与多个算例的对比验证了其方法和程序计算的正确性;对影响土质边坡动态稳定性的一些因素进行了参数分析,分析表明：随着边坡倾角?、坡顶超载q、水平和竖向地震效应影响系数的增大,边坡稳定性安全系数显著下降;随着坡顶超载q、水平地震效应影响系数kh的增大、竖向地震效应影响系数kv的减小,边坡的潜在滑动面越来越深,潜在破坏范围越来越大。竖向地震效应对边坡稳定性也有一定影响,强震条件下的设计计算必须考虑竖向地震效应的影响。 相似文献
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19.
考虑坡顶均布荷载和地震效应典型情况下,将边坡滑体进行任意斜条块划分,建立了具有倾斜界面的多块体破坏模型。基于极限分析上限法和非线性摩尔-库仑破坏准则,考虑岩体内正应力的不均匀性,引入多点切线法和强度折减法推导得出边坡临界破坏状态下的安全系数Fs通用计算公式。采用序列二次规划法对安全系数Fs的目标函数进行最优化计算,并与既有研究成果进行对比分析,其结果具有较好的一致性,相对误差不超过3.565%,表明了该方法的正确性。同时对比传统单点切线法计算结果,多点切线法较单点切线法获得的边坡安全系数值偏小,表明了多点切线斜条分法偏于保守,是安全的。参数分析表明坡顶均布荷载、地震效应和非线性参数均对边坡安全系数及潜在临界滑裂面有重要影响。多点切线法引入非线性摩尔-库仑破坏准则对边坡进行稳定性极限分析,为相关研究人员提供了一种新的思路与方法。 相似文献
20.
Summary A procedure for the stability analysis and design of geosynthetic reinforced soil slopes over a firm foundation is described. Firstly the unreinforced slope is analysed, and for this a circular failure method is used which allows a surcharge load to be taken into account. Any method of slip circle analysis could be used to identify the coordinates of the centre of the slip circle, its radius and the minimum factor of safety. In this study, both internal and external stability analysis of the reinforced slope is presented. Internal stability deals with the resistance to pullout failure within the reinforced soil zone resulting from the soil/reinforcement interaction. The external stability is considered by an extension of the bilinear wedge method which allows a slip plane to propagate horizontally along a reinforcing sheet. The results for total tensile force, internal and external stability are presented in the form of charts.For given properties of soil and slope geometry, the required strength of the geosynthetic and the length of reinforcement at the top and bottom of the slope can be determined using these charts. The results are compared with the published design charts by Schmertmannet al. (1987). 相似文献