反演法在滑坡稳定性评价中的应用分析

本文运用工程实例,采用反演法确定滑带土抗剪强度指标C、ψ值,计算结果更切合实际,具有代表性,解决了试验方法不足,为滑坡稳定性评价、治理方案选择提供了可靠依据,具有适用性。     

露天矿排土场滑坡工程治理

本文在分析露天矿排土场滑坡机制与对策的基础上,以攀矿兰尖铁矿尖山第六排土场滑坡治理为工程实例,论证了由浅层软弱地基引起排土场失稳滑坡工程治理方案选择的依据、原则和工作程序;针对土场地基工程地质与水文地质条件,通过分析滑坡体变形和破坏过程中两年的监测资料,应用极限平衡法计算滑坡推力,确定工程治理设计参数;从多方案比较中,优选出“清基、填石、排水、挡石”综合治理方案。     

某矿区山体滑坡滑带土的抗剪强度性能分析

本论文以某矿区山体滑坡滑带土为例,分析其抗剪性能。本论文分析某矿区山体滑坡滑带土的属性,包括地形地貌、矿层特性、地质构造及矿震以及抗剪强度的主要影响因素。最后,在此基础上,对滑坡的平稳性进行分析,包括总体分析、平稳性分析、平稳综合性分析等内容。     

土质边坡治理中的分析与应用

围绕《建筑地基基础设计规范》(GRJ7-89)中提出的整治滑坡的基本原则即：排水、减重、支挡、反压几方面对影响和治理边坡(滑坡)的因素进行了分析探讨，并介绍了以上分析在作者实际从事设计的攀钢冷轧厂高压电塔滑坡抢险治理工程中的应用及效果。得出了边(滑)坡工程只有综合治理才能取得最佳效果的结论。     

古树包滑坡滑带土蠕变经验模型

针对清江古树包滑坡滑带土的室内蠕变试验资料,结合经验模型理论,以双曲线函数描述蠕变应力-应变关系,并引入Morgan Mercer Florin函数,用来描述应变-时间关系,建立了一种新的蠕变经验模型.采用ε/(-D)-ε关系曲线和遗传算法求解出了该模型的所有参数.经过计算,所建经验模型的计算结果与实际实验数据的相关系数在0.96以上,说明所建经验模型能有效地反映古树包滑坡滑带土的蠕变特性.     

湖南安仁县地质灾害特征与变形机制分析

人类工程活动、大气降雨是诱发地质灾害主要的外因。通过反演分析,滑带土的内摩擦角比粘聚力对滑坡稳定性影响大。通过稳定性计算分析,该滑坡在天然工况下处于欠稳定状态,暴雨工况下处于不稳定状态。针对该滑坡体的特征及现场条件,建议采用抗滑桩+截排水的综合治理方案。     

北岭村后组滑坡稳定性分析

本文以洛阳市嵩县木植街乡北岭村后组滑坡为研究对象,对其基本情况进行了介绍。在地形条件、地层岩性特征和降雨入渗等方面分析了其形成机制;利用相关公式计算了滑坡稳定性系数和剩余下滑推力,分析了滑坡在自重、自重+暴雨、自重+地震三种工况下的稳定性;建议采取治理措施,加固滑坡的抗滑能力,加强监测,防止出现滑坡失稳、造成人员伤亡及房屋毁坏的事故发生。     

地下侵蚀对结晶片岩滑坡活动的影响——以日本善德滑坡为例

为了研究和评价降雨对滑坡活动的影响过程及其作用,利用地表伸缩计、三维地表位移观测计以及地下水流量和地下侵蚀观测计等现场监测仪器,对一典型的日本结晶片岩滑坡--善德滑坡内部的地下侵蚀特征以及地下侵蚀与该滑坡活动之间的关系进行了定量的分析和研究.研究结果表明,季节性集中强降雨是导致地下侵蚀发生的主要原因.善德滑坡地下侵蚀主要有连续土砂排泄和集中土砂排泄2种侵蚀类型,而结晶片岩滑坡的异常活动主要与暴雨引起的集中土砂排泄型地下侵蚀作用有关.通过对地下侵蚀和滑坡活动之间关系的分析发现,地下侵蚀对善德滑坡不同滑体活动的影响作用表现出不同的特征.其中,厚度为10～20 m的浅层滑体,地下侵蚀的影响作用最为显著,而对于具有深层滑动面的滑体(＞20 m)其影响作用并不明显.     

三维确定性模型在浅层黄土滑坡稳定性预测中的应用

浅层黄土滑坡是黄土高原广泛分布和频繁发生的地质灾害,造成了巨大的人员伤亡和财产损失.尽管二维确定性模型已被广泛用于浅层滑坡稳定性预测,但不能充分考虑岩土性质、地层结构、地下水等条件的三维空间变化,这可能与实际的斜坡稳定性不相符.因此,利用能考虑复杂斜坡环境的三维确定性模型评价滑坡稳定性,对获取更真实的评价结果以及指导滑坡防治工作具有重要意义.本文利用Scoops3D三维确定性模型评价了在浅层黄土滑坡稳定性预测中的适应性和可靠性.首先,模型计算参数敏感性的分析发现黏聚力、滑动视倾角和栅格单元重量对安全系数准确度影响较大,并用于指导获取详细的关键参数.然后,选取不同分辨率的数字高程模型(DEM)数据,利用Scoops3D模型对典型黄土沟壑中的浅层黄土滑坡稳定性进行预测,并通过详细的点状和面状滑坡分布图与预测结果的对比发现,该模型对黄土沟壑区的浅层滑坡稳定性预测准确度较高,且点状滑坡分布图可能更适合模型适应性的检验.最后,混淆矩阵法和成功率曲线法对不同分辨率数字高程模型预测结果可靠性的检验显示,该模型能够有效地预测黄土浅层滑坡的稳定性,且在高分辨率数字高程模型数据下可以获得可靠的预测精度.      

重庆市丰都县名山和双桂山滑坡整治刍议

本文论述了丰都县名山，双桂山滑坡整治的原则、方案及分析计算，简要介绍了一些有关滑坡的基本概念，提出了作者的一些观点，尽管该工程尚在设计阶段，整治措施未经实践检验，但就滑坡治理新支挡体系的作用而言，仍是一种有益的尝试，希望能够对今后类似工程提供一定的帮助。     

基于有限元极限平衡法的三维边坡稳定性

提出了一种基于有限元弹塑性应力场和极限平衡状态的三维边坡稳定分析方法——三维有限元极限平衡法。首先,考虑三维空间中滑动方向,提出滑动面上一点在滑动方向上的极限平衡条件,并证明滑动面上土体整体达到极限平衡状态与滑动面上土体各处在滑动方向上处于极限平衡状态等价。再通过刚体极限平衡假定计算主滑方向和滑动面上各点滑动方向。最后,定义局部安全系数为抗剪强度与滑动方向上剪应力投影的比值,基于三维边坡整体极限平衡条件将局部安全系数通过积分中值定理转变为整体安全系数。该方法计算简单,消除了剪应力比形式定义安全系数滑动面形状限制,具备合理性与有效性。算例验证结果表明,该方法滑动方向假设合理,安全系数与严格三维极限平衡法结果一致。      

软土地基堤围稳定性计算方法

在软土地基上采用整体稳定分析方法确定的安全系数可能会存在偏大的危险, 当堤身强度高于堤基软土的强度过多时, 可能存在堤基软土失稳的安全系数小于整体稳定安全系数的情况, 因此, 对于软土地基的堤围稳定计算, 除进行整体稳定计算外, 还应复核堤基软土的稳定性.并通过案例证明了该观点的正确性, 同时提出了软土堤基稳定计算的方法, 并以该方法为基础, 提出了堤脚受冲刷情况下的整体稳定性计算方法.可为软土地基的堤围安全提供更合理安全的设计计算方法.      

Unsaturated Infinite Slope Stability Considering Surface Flux Conditions

A slope stability model is derived for an infinite slope subjected to unsaturated infiltration flow above a phreatic surface. Closed form steady state solutions are derived for the matric suction and degree of saturation profiles. Soil unit weight, consistent with the degree of saturation profile, is also directly calculated and introduced into the analyzes, resulting in closed-form solutions for typical soil parameters and an infinite series solution for arbitrary soil parameters. The solutions are coupled with the infinite slope stability equations to establish a fully realized safety factor function. In general, consideration of soil suction results in higher factor of safety. The increase in shear strength due to the inclusion of soil suction is analogous to making an addition to the cohesion, which, of course, increases the factor of safety against sliding. However, for cohesive soils, the results show lower safety factors for slip surfaces approaching the phreatic surface compared to those produced by common safety factor calculations. The lower factor of safety is due to the increased soil unit weight considered in the matric suction model but not usually accounted for in practice wherein the soil is treated as dry above the phreatic surface. The developed model is verified with a published case study, correctly predicting stability under dry conditions and correctly predicting failure for a particular storm.     

FAO-56 Dual Crop Coefficient Method for Estimating Evaporation from Soil and Application Extensions

Crop coefficient curves provide simple, reproducible means to estimate crop evapotranspiration (ET) from weather-based reference ET values. The dual crop coefficient (Kc) method of the Food and Agricultural Organization of the United States (FAO) Irrigation and Drainage Paper No. 56 (FAO-56) is intended to improve daily simulation of crop ET by considering separately the contribution of evaporation from soil. The dual method utilizes “basal” crop coefficients representing ET from crops having a dry soil surface and separately predicts evaporation from bare soil based on a water balance of the soil surface layer. Three extensions to the evaporation calculation procedure are described here that are intended to improve accuracy when applications warrant the extra complexity. The first extension uses parallel water balances representing the portion of the soil surface wetted by irrigation and precipitation together and the portion wetted by precipitation alone. The second extension uses three “stages” for surface drying and provides for application to deep cracking soils. The third extension predicts the extraction of the transpiration component from the soil surface layer. Sensitivity and analyses and illustrations indicate moderate sensitivity of daily calculated ET to application of the extensions. The dual Kc procedure, although relatively simple computationally and structurally, estimates daily ET as measured by lysimeter relatively well for periods of bare soil and partial and full vegetation cover.     

Meta-Analysis of 301 Slope Failure Calculations. I: Database Description

Since the early part of the twentieth century, two-dimensional limit equilibrium (2DLE) analysis has been the scientific community’s primary means of slope stability calculation. However, it is well established that the input parameters to 2DLE, namely, soil strength and anisotropy, slope geometry, pore water pressures, failure surface geometry, applicable correction factors, and loading conditions are all inherently uncertain. Effective modeling must account for these uncertainties statistically. Unfortunately, most of the key statistical parameters, such as the safety factor statistical distribution and standard deviation (sd), are unknown and must be estimated by the analyst. In response to this growing need for statistical information, a database was established from the literature of 157 different failed slopes and the corresponding published 301 safety factor (SF) calculations. The database, which covered more than five decades of slope stability research, also included a number of the slope stability factors, including analytical method used, stress approach (effective versus total), assumed slip surface geometry, slope type, applied correction factors, and soil Atterberg limits. A temporal analysis found no evidence that SF prediction or deviation had significantly changed. A log (base 10) normal distribution was found to adequately describe the SF data, with a (nontransformed) mean of 1.03 and a (transformed) sd of 0.087, but the pronounced curvature of the residuals indicated significant, unresolved slope factors, further investigated in the companion paper.     

基于EBSD的金属变形激活滑移系的确定方法

针对多晶金属力学变形过程中的激活滑移系,提出了一种基于电子背散射衍射(Electron Back-Scatter Diffraction,EBSD)技术的滑移系确定方法。借助材料表面晶体取向和滑移带形貌分析,计算并测量滑移带与加载应力轴之间的夹角,通过两者比较确定滑移面;计算该滑移面对应的可能滑移系的Schmid因子,根据Schmid定律确定滑移方向,从而判断实际被激活滑移系。以奥氏体不锈钢为例,试验证实了该方法的可行性。与其他方法相比,该方法可获得表面损伤形貌及其晶体取向分布,更适用于多晶材料力学变形后的滑移系分析。     

强度折减法在某尾矿坝边坡稳定性分析中的应用

利用有限元强度折减法对某尾矿坝的边坡稳定性进行了计算,同时利用简化毕肖普法和瑞典圆弧法对该坝体的边坡稳定性进行了计算。通过对比分析,有限元强度折减法的计算值与考虑条块间作用力的简化毕肖普法的计算值基本一致,证明基于有限元理论的强度折减法的计算结果是合理的,其安全系数值可以作为该尾矿工程定量判断的依据。     

持续暴雨作用下排土场层状碎石土边坡稳定性

为了研究排土场层状碎石土边坡在持续暴雨条件下的入渗过程及稳定性,推导了土体天然含水率、天然重度与天然体积含水量的换算公式,作为快速确定边坡土体初始基质吸力分布的依据.建立算例排土场有限元分析模型,进行降雨条件下饱和-非饱和渗流、孔压-应力耦合以及边坡稳定分析.结果表明:持续暴雨作用下排土场会在透水性最强的边坡浅层形成集中渗流通道,当坡底存在弱透水性土层时会切断渗流通道,导致雨水从坡脚涌出;排土场边坡位移在降雨期间不断增长,但增长速度越来越慢,雨后边坡位移立即开始减小;降雨初期边坡稳定性系数下降较快,边坡浅层渗流稳定后基本保持不变,雨后缓慢增大.排土场层状碎石土边坡在持续暴雨作用下容易在降雨中后期失稳.      

A mechanism of fatigue failure

It was shown that when specimens of 2014-T6 aluminum, titanium (6 Al-4 V), and 4130 steel were fatigued, the strength of the surface layer increased. When the strength of this layer reached a critical value, independent of the cyclic stress amplitude a fatigue crack was initiated. The increase in the fatigue life by periodically removing the outer layer of a specimen was investigated under conditions where persistent slip bands or cracks were not present. The results indicate that the increase in fatigue life is associated with a decreased strength of the surface layer resulting from the removal of the high density dislocation layer at the surface.     

Simultaneous Determination of Critical Slip Surface and Reliability Index for Slopes

This paper presents a new method for applying reliability-based design approaches to slope stability analysis. In this method the soil properties are considered to be random variables. The factor of safety of the slope is found using Bishop’s simplified method for noncircular slip surfaces. By considering the variability of the soil properties, the probability of failure is determined from the reliability index (β). The minimization problem (determination of the lowest β value for the range of variables and possible slip surfaces considered) is solved using a genetic algorithm approach, which simultaneously locates the critical slip surface and determines the reliability index. The performance of the new method is compared to some existing reliability approaches when applied to case histories of slope failures from the geotechnical literature. The new approach is seen to provide reasonable and consistent estimates of the reliability index and critical slip surface.