高陡边坡稳定性的概率分析

将概率方法应用于某高陡岩质路堑边坡的稳定性分析。通过适当降低岩土体的力学参数来间接考虑岩体节理裂隙的影响，并对加固后的边坡进行了同样的计算，认为加固后边坡处于稳定状态，与实际情况吻合。     

某高等级公路路堑边坡预应力锚索加固设计

高等级公路穿越山区时 ,通常需要开挖而形成路堑边坡 ,其边坡的稳定性将危及公路施工和运营安全 ,故常需要对不稳定边坡进行加固处理。对具有大体积、大面积范围且存在滑动面的不稳定岩土体 ,加固方法以预应力锚索为佳。在结合某高等级公路路堑高边坡工程中 ,分析了已有地质条件的基础上 ,提出了预应力锚索加固边坡的设计方案     

蓬莱阁丹崖山安全监测与分析

丹崖山边坡稳定性是关系古文物蓬莱阁安全的关键问题。丹崖山边坡高差大、断层裂隙发育、岩体卸荷深度大,地质条件十分复杂,边坡在施工期和运行期的稳定性问题特别突出。该文介绍了丹崖山岩体加固后的监测布置,并对岩体表面变形趋势、空间分布形态、加固后变形趋势进行分析,通过对多点位移计、锚杆测力计、锚索测力计、表面裂缝计及地表变形等监测结果进行综合分析,得到边坡岩体的变形规律。     

锚杆不确定性对加固边坡失稳概率的影响

为了探究锚杆不确定性对加固边坡失稳概率的影响, 建立了施加锚杆后的边坡模型, 通过以下两种途径来考虑锚杆的不确定性: 其一是假定锚杆与锚固体之间接触面上的单位表面摩擦力为对数正态分布变量, 其二是引入锚杆与锚固体之间接触面上的单位表面摩擦力衰减系数来考虑运营过程中锚杆的不确定性。采用极限平衡分析法并结合蒙特卡罗抽样法, 计算并对比分析了两种途径下锚固边坡失稳概率变化曲线, 最后以深圳假日酒店基坑边坡支护工程为例, 证明所提方法的有效性。结果表明: 对于途径一, 在相同土体统计参数下, 随着锚杆与锚固体之间接触面上单位表面摩擦力变异系数的增加, 加固边坡的失稳概率缓慢增加, 增幅介于18.03%~41.90%之间。对于途径二, 随着锚杆衰减系数自1.0逐步减小至0, 加固边坡失稳概率迅速增加, 增幅介于55.64%~124.90%之间; 在同一衰减系数下, 加固边坡失稳概率随着锚杆衰减根数的增加而增大。研究结果可以为锚杆施工与运营期间的管理提供决策支持。      

开挖对顺向岩质高边坡稳定性影响及锚索加固效果分析

顺向岩质高边坡的稳定性通常较差,在工程上格外受到重视,利用锚索锚固是较为理想的加固方案。利用Sarma法对厦沙高速公路某段石英片岩顺向岩质高边坡在施加锚索和不加锚索两种工况下的应力特征和边坡稳定性系数进行对比分析。结果表明:不加锚索时,各条块底面正压力随开挖过程呈降低趋势,越靠近边坡顶部,各条块底面正压力受到开挖卸荷的影响越大,降低趋势越明显;条块底面正压力的降低使边坡抗滑力减小,当减小幅度较大时,边坡稳定性会受到明显影响,整个开挖过程中边坡整体稳定性系数呈下降趋势,最低为1.243;施加锚索能够增大条块底面正压力,提高条块底面的抗滑力,有效降低条块底面受到的剪切力,限制上部条块的滑动趋势,减小其对下部条块的挤压和相对错动,且随着开挖的加深,这种效应表现得越明显;对某个条块而言,施加锚索可以提高底面抗剪强度,降低底面和侧面剪切力、条块下滑力,从而提高边坡稳定性;施加锚索后边坡稳定性系数提高到1.630。综上所述,边坡开挖对于顺向岩质高边坡稳定性影响很大,而施加锚索加固可以显著提高边坡稳定性,达到加固边坡的目的。     

基于灰色关联分析法的边坡敏感性分析

综合考虑边坡坡高、角度、岩土体黏聚力、摩擦角和容重等因素对边坡稳定性的影响,通过有限单元应力法建立数值模
型,进行应力分析,最后计算得到边坡安全系数,这一方法将数值分析和极限平衡方法有机地融合在一起,达到优势互补的效果;
然后基于灰色关联分析法对有限单元应力法得到的数据建立数学模型,对各影响因素与安全系数进行关联分析,最后得到各影响
因素对边坡稳定性影响的敏感性。结果表明:影响边坡稳定性的因素敏感性依次为黏聚力、容重、摩擦角、边坡角度和坡高。利用
敏感性分析结果,可对边坡加固位置提出设计改进,将有限的加固措施加于敏感性较高的位置,能够更有效地提高边坡的稳定性。      

断层破碎带条件下组合式圆截面抗滑桩加固边坡效果研究

随着我国公路建设不断向山区深入, 在地质构造复杂区公路边坡遇到断层破碎带的情况日渐增多, 亟需开展阻滑能力强的抗滑桩结构加固边坡研究。传统的人工挖孔桩施工模式存在高风险、低效率等缺点, 而组合式圆截面抗滑桩具有施工效率高、安全便捷等特点, 为此, 探究其对含断层破碎带边坡的加固效果具有现实意义。采用自主设计的边坡物理试验系统, 设计了5种不同破碎带厚度与组合式圆截面抗滑桩组合的物理模型, 采用坡顶逐级加载的方式模拟加载, 监测桩身应变、桩顶位移和桩后土压力, 采用高速相机捕捉滑体变形破坏图像, 并使用粒子图像测速(PIV)技术对图像进行处理。研究结果表明: 组合式圆截面抗滑桩通过限制桩后滑体水平位移, 并将滑体限制在前、后排桩间来达到加固边坡的效果; 滑体演化分为变形压密、加速变形和破坏滑移3个阶段; 前、后排桩桩后土压力比值介于1/3~1/2之间; 随断层破碎带厚度增加, 滑体水平滑移速率增大, 组合式圆截面抗滑桩的桩顶位移增大, 桩身最大正弯矩减小。模型试验与数值模拟计算的弯矩及桩顶位移较为吻合, 研究成果可为边坡工程组合式圆截面抗滑桩设计提供一定借鉴与参考。      

姑山矿东帮河堤防渗工程优化设计的有限元分析

根据河堤和边坡的实际地质模型,基于线弹性理论的本构方程,通过有限元模拟分析,定量地揭示和模拟边坡及河堤的破坏、变形和失稳前后的过程和机制,探讨了高压及水流作用下防渗墙的破坏机理,并对边坡整治及河堤防渗加固提供可行的论证和建议。     

深开挖岩石边坡三维随机楔体的稳定性分析

针对水工建筑物深开挖边坡中常出现的随机楔体,应用概率与统计学理论,分析组成楔体结构面的分布及组合特征,采用三维结构面网络模拟的方法模拟边坡工程中的结构面分布,进一步研究随机楔体稳定性及分布规律,提出了三维随机楔体的稳定性系统分析方法,为边坡加固提供了理论依据。     

基于有限元强度折减系数法岩土边坡稳定性分析与抗滑桩设计

基于有限元强度折减系数法原理,应用具有折减分析功能的ANSYS软件,以暴雨工况为最不利控制工况,采用平面应变条件下Drucker-Prage关联流动屈服准则(DP4)和边坡失稳破坏综合判据,分别对龙胜县城桑江北区不稳定高切边坡自然状态和削坡及抗滑桩加固状态进行了强度折减数值模拟。确定了这2种状态边坡最危险滑动面位置、形状并给出了极限状态坡体强度储备安全系数,通过所建桩-土共同作用连续介质模型及ANSYS后处理路径分析功能,求得极限状态滑坡设计推力和桩身内力及其分布,且将该法分析结果与传统分析方法作对比,发现误差很小且该法更接近边坡实际情况。综合分析表明,该法在岩土边坡滑坡灾害防治方面是可行且有效的新途径,有其自身的优越性和广阔的发展前景。      

济南高陡土质边坡稳定性分析及治理方法探讨——以济南南部山区山间平原为例

在济南山前及山间倾斜平原区常见土质边坡存在较大安全隐患,本文结合实例,对此类边坡开展稳定性评价及治理方法研究,对不稳定边坡的成因做了详细分析,并采用毕肖普条分法对边坡稳定性进行了定量计算,提出清坡+格构+钢筋混凝土挡板+截水沟的方案解决土质边坡失稳问题。治理后边坡滑动安全系数为1.673,实现了土质边坡的有效防治,为此类土质边坡失稳问题提供了新的治理思路。     

Analysis of the stability and seismic behavior of the geosynthetic-reinforced embankments under earthquake

The stability and seismic behavior of geosynthetic-reinforced embankments during the earthquake is not well known.In this paper,the damage types of embankments were summarized,and the seismic stability of reinforced embankment were analyzed through an earthquake damage investigation in the Wenchuan earthquake region.Then,large-scale shaking table model tests were performed on the geosynthetic-reinforced embankment.The results show that the damage level of the reinforced embankment was almost less than that of the unreinforced embankment.The peak seismic earth pressure was nonlinear along the height of the embankment,the largest peak seismic earth pressure was roughly in the middle of the embankment slope.The peak ground accelerations(PGA)amplification factor first showed an increasing pattern and then a decreasing pattern with the increase of elevation,but there was a final increasing trend along the height of the reinforced embankment.The results can help to establish the proper design of the reinforcement embankments under earthquake conditions.     

Dynamic response of a slope reinforced by double-row antisliding piles and pre-stressed anchor cables

Large-scale shaking table tests were conducted to study the dynamic response of a slope reinforced by double-row anti-sliding piles and prestressed anchor cables. The test results show that the reinforcement suppressed the acceleration amplification effectively. The axial force time histories are decomposed into a baseline part and a vibration part in this study. The baseline part of axial force well revealed the seismic slope stability, the peak vibration values of axial force of the anchor cables changed significantly in different area of the slope under seismic excitations. The peak lateral earth pressure acting on the back of the anti-sliding pile located at the slope toe was much larger than that acting on the back of the anti-sliding pile located at the slope waist. The test results indicate an obvious load sharing ratio difference between these two anti-slide piles, the load sharing ratio between the two anti-sliding piles located at the slope toe and the slope waist varied mainly in a range of 2-5. The anti-slide pile at the slope waist suppressed the horizontal displacement of the slope surface.     

Geotechnical investigations and remediation design for failure of tunnel portal section: a case study in northern Turkey

Mass movements are very common problems in the eastern Black Sea region of Turkey due to its climate conditions, geological, and geomorphological characteristics. High slope angle, weathering, dense rainfalls, and anthropogenic impacts are generally reported as the most important triggering factors in the region. Following the portal slope excavations in the entrance section of Cankurtaran tunnel, located in the region, where the highly weathered andesitic tuff crops out, a circular toe failure occurred. The main target of the present study is to investigate the causes and occurrence mechanism of this failure and to determine the feasible remedial measures against it using finite element method (FEM) in four stages. These stages are slope stability analyses for pre- and postexcavation cases, and remediation design assessments for slope and tunnel. The results of the FEM-SSR analyses indicated that the insufficient initial support design and weathering of the andesitic tuffs are the main factors that caused the portal failure. After installing a rock retaining wall with jet grout columns and reinforced slope benching applications, the factor of safety increased from 0.83 to 2.80. In addition to slope stability evaluation, the Rock Mass Rating (RMR), Rock Mass Quality (Q) and New Austrian Tunneling Method (NATM) systems were also utilized as empirical methods to characterize the tunnel ground and to determine the tunnel support design. The performance of the suggested empirical support design, induced stress distributions and deformations were analyzed by means of numerical modelling. Finally, it was concluded that the recommended stabilization technique was essential for the dynamic long-term stability and prevents the effects of failure. Additionally, the FEM method gives useful and reasonably reliable results in evaluating the stability of cut slopes and tunnels excavated both in continuous and discontinuous rock masses.     

Interaction between anti-shear galleries and surrounding rock in the right-bank slope of Dagangshan hydropower station

The right-bank slope of the Dagangshan hydropower station located in Southwest China is a highly unloaded rock slope. Moreover, large-scale natural faults were detected in the slope body; some excavation-induced unloading fractures were discovered at elevations between 1075m and 1146m. Because of poor tectonic stability, the excavation work was suspended in September 2009, and six largescale anti-shear galleries were employed to replace the weak zone in the slope body to reinforce the rightbank slope. In this study, based on microseismicmonitoring technology and a numerical-simulation method, the stabilities of the slope with and without the reinforcement are analysed. An in-situ microseismic-monitoring system is used to obtain quantitative information about the damage location, extent, energy, and magnitude of the rocks. Thus, any potential sliding block in the right-bank slope can be identified. By incorporating the numerical results along with the microseismic-monitoring data, the stress concentration is found to largely occur around the anti-shear galleries, and the seismic deformation near the anti-shear galleries is apparent, particularly at elevations of 1210, 1180, 1150, and 1120m. To understand the interaction mechanism between the anti-shear gallery and the surrounding rock, a 2D simulation of the potential damage process occurring in an anti-shear gallery is performed. The numerical simulation helps in obtaining additional information about the stress distribution and failure-induced stress re-distribution in the vicinity of the anti-shear galleries that cannot be directly observed in the field. Finally, the potential sliding surface of the right-bank slope is numerically obtained, which generally agrees with the spatial distribution of the in-situ monitored microseismic events. The safety factor of the slope reinforced with the anti-shear gallery increases by approximately 36.2%. Both the numerical results and microseismic data show that the anti-shear galleries have a good reinforcement effect.     

一种基于AutoLISP的地形图斜坡类要素处理程序的设计与实现

在大比例尺地形图编辑中存在大量的依比例斜坡类符号要素,包括依比例斜坡、干堤、加固岸、路堤、路堑等,该类符号是一种复合性符号,由坡顶线和坡面两部分组成,坡顶线由坡顶母线和长短齿符号组成,其中长齿长度和坡面宽度一致且垂直于坡顶母线,该符号表示复杂,编辑工作较为费时费力。利用AutoLISP语言开发斜坡类符号要素处理程序,实现符号长齿自动延伸,可大大提高该类符号编辑工作效率,提升制图表达效果。     

延安市区斜坡稳定性两级模糊综合评判

本文采用两级模糊综合评判方法,在对延安市区斜坡稳定性进行定性分析和评价的基础上,选取主要影响因素作为评价指标并将其定量化,然后按不稳定、次不稳定、基本稳定和稳定等四个级别进行了延安市区斜坡稳定性两级模糊综合评判。评判结果较好地反映了市区斜坡带的实际稳定程度。该方法清晰易用,能使较多的影响因素参与评判,是进行斜坡稳定性定量化研究的一个有效途径。     

基于可拓工程法的黄土路堑边坡稳定性评价方法

针对影响黄土路堑边坡稳定性因素的复杂性和模糊性,重视实践中的经验,将可拓工程方法与路堑边坡稳定性评价相结合,提出了路堑边坡稳定性评价的物元关联函数及物元关联度的计算方法。建立了适合可拓学理论的边坡稳定性分类标准,实现了定性与定量评价黄土路堑边坡的结合。实例评价结果与定值计算、工程实际调查结果一致。