Integrated simulation and monitoring to analyze failure mechanism of the anti-dip layered slope with soft and hard rock interbedding

The significant difference between the mechanical properties of soft rock and hard rock results in the complexity of the failure mode of the anti-dip layered slope with soft and hard rock interbedding.In order to reveal the landslide mechanism,taking the north slope of Fushun West Open-pit Mine as an example,this paper analyzed the failure mechanism of different landslides with monitoring and field surveys,and simulated the evolution of landslides.The study indicated that when the green mudstone(hard rock)of the anti-dip slope contains siltized intercalations(soft rock),the existence of weak layers not only aggravates the toppling deformation of anti-dip layered slope with high dip,but also causes the shear failure of anti-dip layered slope with stable low dip.The shear failure including subsidence induced sliding and wedge failure mainly exists in the unloading zone of the slope.Its failure depth and failure time were far less than that of toppling failure.In terms of the development characteristics of deformation,toppling deformation has the long-term and progressive characteristics,but shear failure deformation has the abrupt and transient characteristics.This study has deepened the understanding of such slope landslide mechanism,and can provide reference for similar engineering.

Effect of the inclined weak interlayers on the rainfall response of a bedded rock slope

Engineering experience shows that outward dipping bedded rock slopes, especially including weak interlayers, are prone to slide under rainfall conditions. To investigate the effect of inclined weak interlayers at various levels of depth below the surface on the variation of displacements and stresses in bedded rock slopes, four geomechanical model tests with artificial rainfall have been conducted. Displacements, water content as well as earth pressure in the model were monitored by means of various FBG(Fiber Bragg Grating) sensors. The results showed that the amount of displacement of a slope with a weak interlayer is 2.8 to 6.2 times larger than that of a slope without a weak interlayer during one rainfall event. Furthermore, the position of the weak interlayer in terms of depth below the surface has a significant effect on the zone of deformation in the model. In the slope with a high position weak interlayer, the recorded deformation was larger in the superficial layer of the model and smaller in the frontal portion than in the slope with a low position weak interlayer. The slope with two weak interlayers has the largest deformation at all locations of all test slopes. The slope without a weak interlayer was only saturated in its superficial layer, while the displacement decreased with depth. That was different from all slopes with a weak interlayer in which the largest displacement shifted from thesuperficial layer to the weak interlayer when rainfall persisted. Plastic deformation of the weak interlayer promoted the formation of cracks which caused more water to flow into the slope, thus causing larger deformation in the slope with weak interlayers. In addition, the slide thrust pressure showed a vibration phenomenon 0.5 to 1 hour ahead of an abrupt increase of the deformation, which was interpreted as a predictor for rainfall-induced failure of bedded rock slopes.

Physical Modeling of Landslide Mechanism in Oblique Thick-Bedded Rock Slope: A Case Study

The Jiweishan landslide illustrates the failure pattern of an apparent dip slide of an oblique thick-bedded rockslide. Centrifugal modeling was performed using a model slope consisting of four sets of joints to investigate the landslide initiation mechanism. Crack strain gauges pasted between the slide blocks and the base failed in sequence from the rear to the front as the centrifugal acceleration increased. When the acceleration reached 16.3g, the instantaneous failure of the key block in the front triggered the apparent dip slide of all blocks. The physical modeling results and previous studies suggest that the strength reduction in the weak layer and the failure of the key block are the main reasons for the Jiweishan landslide. The centrifuge experiment validated the previously proposed driving-blocks-key-block model of apparent dip slide in oblique with inclined bedding rock slopes. In addition, the results from limit equilibrium method and centrifuge test suggest that even though the failure of the key block in the front is instantaneous, a progressive stable-unstable transition exists.

Model test and numerical simulation on the dynamic stability of the bedding rock slope under frequent microseisms

Shake table testing was performed to investigate the dynamic stability of a mid-dip bedding rock slope under frequent earthquakes. Then, numerical modelling was established to further study the slope dynamic stability under purely microseisms and the influence of five factors, including seismic amplitude, slope height, slope angle, strata inclination and strata thickness, were considered. The experimental results show that the natural frequency of the slope decreases and damping ratio increases as the earthquake loading times increase. The dynamic strength reduction method is adopted for the stability evaluation of the bedding rock slope in numerical simulation, and the slope stability decreases with the increase of seismic amplitude, increase of slope height, reduction of strata thickness and increase of slope angle. The failure mode of a mid-dip bedding rock slope in the shaking table test is integral slipping along the bedding surface with dipping tensile cracks at the slope rear edge going through the bedding surfaces. In the numerical simulation, the long-term stability of a mid-dip bedding slope is worst under frequent microseisms and the slope is at risk of integral sliding instability, whereas the slope rock mass is more broken than shown in the shaking table test. The research results are of practical significance to better understand the formation mechanism of reservoir landslides and prevent future landslide disasters.

Dynamic damage evolution of bank slopes with serrated structural planes considering the deteriorated rock mass and frequent reservoirinduced earthquakes

To investigate the dynamic damage evolution characteristics of bank slopes with serrated structural planes,the shaking table model test and the numerical simulation were utilized.The main findings indicate that under continuous seismic loads,the deformation of the bank slope increased,particularly around the hydro-fluctuation belt,accompanying by the pore water pressure rising.The soil pressure increased and then decreased showed dynamic variation characteristics.As the undulation angle of the serrated structural planes increased(30°, 45°, and 60°),the failure modes were climbing,climbinggnawing,and gnawing respectively.The first-order natural frequency was used to calculate the damage degree(Dd)of the bank slope.During microseisms and small earthquakes,it was discovered that the evolution of Dd followed the“S”shape,which was fitted by a logic function.Additionally,the quadratic function was used to fit the Dd during moderately strong earthquakes.Through the numerical simulation,the variation characteristics of safety factors(Sf)for slopes with serrated structural planes and slopes with straight structural planes were compared.Under continuous seismic loads,the Sf of slopes with straight structural planes reduce stalely,whereas the Sf for slopes with serrated structural planes was greater than the former and the reduction rate was increasing.

Experimental study on seismic response and progressive failure characteristics of bedding rock slopes

Bedding rock slopes are common geological features in nature that are prone to failure under strong earthquakes. Their failures induce catastrophic landslides and form barrier lakes, posing severe threats to people’s lives and property. Based on the similarity criteria, a bedding rock slope model with a length of3 m, a width of 0.8 m, and a height of 1.6 m was constructed to facilitate large-scale shaking table tests.The results showed that with the increase of vibration time, the natural frequency of the model slope decreased, but the damping ratio increased. Damage to the rock mass structure altered the dynamic characteristics of the slope;therefore, amplification of the acceleration was found to be nonlinear and uneven. Furthermore, the acceleration was amplified nonlinearly with the increase of slope elevation along the slope surface and the vertical section, and the maximum acceleration amplification factor(AAF) occurred at the slope crest. Before visible deformation, the AAF increased with increasing shaking intensity;however, it decreased with increasing shaking intensity after obvious deformation. The slope was likely to slide along the bedding planes at a shallow depth below the slope surface. The upper part of the slope mainly experienced a tensile-shear effect, whereas the lower part suffered a compressive-shear force. The progressive failure process of the model slope can be divided into four stages, and the dislocated rock mass can be summarized into three zones. The testing data provide a good explanation of the dynamic behavior of the rock slope when subjected to an earthquake and may serve as a helpful reference in implementing antiseismic measures for earthquake-induced landslides.

含建筑桩基的顺层岩质边坡桩锚支护体系振动台模型试验研究

基于Bockinghamπ定理,对具有建筑桩基的顺层岩质边坡桩锚支护体系开展振动台模型试验,通过分析预应力锚索、建筑桩基的应变以及边坡坡顶加速度,研究支护体系的动力响应规律。结果表明,预应力锚索的应变在地震波加速度达到峰值时达到最大值,且上排锚索受力大于下排锚索,随着地震幅值的增大,最上排锚索锚固段率先发生滑移破坏失去锚固作用;建筑桩基应变最大值点位于滑动面以下一定深度,且远离边坡坡面的建筑桩基受力大于邻近边坡坡面的建筑桩基;坡顶各点峰值加速度随地震波幅值增大整体表现为线性增大,但在Wenchuan-Wolong波(0.55g)和Sin波(0.4g)工况时,各点峰值加速度相对有所下降,随着地震波幅值增大,各点峰值加速度放大系数在汶川波和正弦波作用下并非单调变化,而是表现为先减小后增大波动变化特点。

抗滑桩爆破开挖引起多台阶顺层岩质边坡振动响应分析

为了研究临近抗滑桩施工爆破引起多台阶顺层边坡的振动响应规律,结合巫镇高速公路边坡工程,联合LS-DYNA和FLAC3D软件建立了抗滑桩爆破模型和多台阶顺层岩质边坡动力计算模型,分析了抗滑桩施工爆破荷载特征及其引起多台阶顺层边坡振动速度变化规律。结果表明,抗滑桩施工爆破最大荷载具有水平向小、竖向大的特点,其引起边坡坡面的振动响应特征表现为①坡体下部水平振速大于竖向振速,坡体上部竖向振速大于水平振速;②多台阶顺层岩质边坡坡面具有高程放大效应,且竖向振速放大率大于水平振速;③多台阶顺层岩质边坡内部具有“趋表放大效应”,坡体不同部位的“趋表放大效应”特征显著不同;④坡面下部水平向振速衰减率大于竖向衰减率,坡面上部竖向衰减率(放大率)大于水平向衰减率,各阶边坡坡脚处振动速度衰减率大于坡顶处衰减率。

基于FLAC3D的边坡支护方案优化研究

为研究抗滑桩及锚杆框架梁在顺层岩质边坡支护中的优化方法,基于三级支护的典型顺层岩质边坡,通过FLAC3D建立数值模型进行计算,对抗滑桩桩身长度及桩身截面积、锚杆锚固倾角及锚固长度进行优化。结果表明,不同长度抗滑桩对岩质边坡进行支护时,抗滑桩稳定系数均随着桩身长度的减小而减小,且在边坡岩性发生突变的地方抗滑桩的水平位移也会发生突变,在一定范围内适当减短抗滑桩的桩身长度并不会引起桩身水平位移的大幅度改变,故在满足规范的条件下可通过减小桩身长度来进行优化设计。改变抗滑桩的截面面积并不会显著改变桩身的水平位移,但抗滑桩截面面积会显著影响抗滑桩稳定系数,存在一个临界截面积使得桩身截面积在小于临界面积时,稳定系数随着截面积的减小迅速减小,而在桩身截面积大于临界面积时,稳定系数随着截面积的减小只会略微减小。边坡最大水平位移随着锚杆锚固倾角的增加、锚固长度的增加而增加,边坡稳定系数随着锚杆锚固倾角的增加、锚固长度的增加而增加,故在进行锚杆框架支护设计时可通过增大锚固倾角及增加锚固长度提高边坡稳定性,此结果可为抗滑桩及锚索框架梁在顺层岩质边坡支护提供优化设计方案。

降雨作用下倾斜层理岩质边坡稳定性数值模拟分析

为研究倾斜层理的岩质边坡在降雨条件下的稳定性情况,结合云南普朗铜矿重点地质灾害协同演变及智能监测预警系统关键技术研究工程实践,选取普朗地区一处具有代表性的边坡,采用数值模拟软件进行单项流固耦合分析,从边坡的含水率、坡体位移和安全系数等方面,进行不同层理倾角的边坡稳定性分析。研究结果表明坡体处于稳定状态,层理倾角的大小会对边坡的稳定性产生影响,层理倾角为75°时,坡体的最大位移量最小,安全系数最大。

缓倾软弱夹层对顺层岩质边坡稳定性的影响

为详细了解缓倾软弱夹层对顺层边坡稳定性的影响,以广西六宾高速K23+350~K23+550右侧挖方边坡为例,采用理论计算和数值模拟的方法开展软弱夹层对上覆弃渣体顺层岩质边坡稳定性影响的研究。研究结果表明,在最不利工况下软弱结构面处的位移相对较小,岩质顺层边坡处于稳定状态。弃渣体堆载体部分在暴雨工况下安全系数不满足规范要求,需对其进行加固。

珠海市南水镇金龙边坡变形破坏特征及稳定性评价

边坡稳定性分析评价是边坡调查评价过程中一个不可或缺的环节。以珠海市金龙边坡为研究对象,分析了边坡的发育特征、影响因素、形成机制。在查明边坡岩土体出露及结构特征基础上,根据典型断面C、ϕ值反演分析及敏感性分析结果,确定金龙边坡岩土体物理力学参数,采用极限平衡法对金龙边坡进行稳定性分析评价。评价结果表明:金龙边坡在天然工况下处于欠稳定状态,在饱和及饱和+地震工况下处于不稳定状态。

基于离散元的顺层岩质边坡加固及稳定性分析

为研究顺层岩质边坡加固机理及稳定性问题,基于离散元方法,利用FLAC 3D软件建立二维模型,对岩体参数敏感性进行了分析,同时得出抗滑桩加固机理.主要得到以下结论:岩层倾角、坡角、内摩擦角和黏聚力对顺层岩质边坡稳定性影响显著,边坡安全系数对坡角和内摩擦角的改变更为敏感;内摩擦角以及黏聚力的增大会导致边坡抗剪强度增大,使抗滑力大于下滑力,进而使顺层岩质边坡安全系数增大;通过研究抗滑桩的布设以及桩间距,发现桩间距为2D~3.5D时,桩位5号时为最优布设位.

老河口市红层边坡崩塌危岩体运动轨迹及冲击能量分析

本文以汉丹铁路沿线切坡形成的陡崖边坡为研究对象,分析危岩段的边坡特征,对危岩体特征进行分类,运用Rockfall软件模拟滚石崩落轨迹,综合预测滚石冲击能量,对老河口地区及同类型红层边坡变形破坏的防治具有指导意义及参考价值。研究表明:区内多数落石的最大水平运动距离在15m左右,最远运动距离接近32m,沿线危岩体直接威胁平台处的汉丹铁路和下方居民建筑安全,不威胁S302省道及省道过往行人和车辆;建议加强沿线专业监测,局部辅以喷浆防护。

基于Geo-slope软件的码头陆域顺层岩质高边坡分级加固计算

针对山区河流码头陆域开挖形成高30~50 m顺层岩质边坡的加固处理问题,根据加固设计方案中格构锚索和抗滑桩的排间距,采用Geo-slope软件,在摩根斯坦-普拉斯法的基础上,建立顺层岩质高边坡加固计算模型,计算多组不同排间距不同工况下的边坡稳定安全系数,从而选定经济安全的边坡加固组合方案。结果表明,格构锚索与抗滑桩加固对边坡整体安全系数的影响大小取决于支护结构在整个滑面上产生抗力的大小。

Optimal mining sequence for coal faces under a bedding slope:insight from landslide prevention

Repetitive mining beneath bedding slopes is identified as a critical factor in geomorphic disturbances, especially landslides and surface subsidence. Prior research has largely concentrated on surface deformation in plains due to multi-seam coal mining and the instability of natural bedding slopes, yet the cumulative impact of different mining sequences on bedding slopes has been less explored. This study combines drone surveys and geological data to construct a comprehensive three-dimensional model of bedding slopes. Utilizing FLAC3D and PFC2D models, derived from laboratory experiments, it simulates stress, deformation, and failure dynamics of slopes under various mining sequences. Incorporating fractal dimension analysis, the research evaluates the stability of slopes in relation to different mining sequences. The findings reveal that mining in an upslope direction minimizes disruption to overlying strata. Initiating extraction from lower segments increases tensile-shear stress in coal pillar overburdens, resulting in greater creep deformation towards the downslope than when starting from upper segments, potentially leading to localized landslides and widespread creep deformation in mined-out areas. The downslope upward mining sequence exhibits the least fractal dimensions, indicating minimal disturbance to both strata and surface. While all five mining scenarios maintain good slope stability under normal conditions, recalibrated stability assessments based on fractal dimensions suggest that downslope upward mining offers the highest stability under rainfall, contrasting with the lower stability and potential instability risks of upslope downward mining. These insights are pivotal for mining operations and geological hazard mitigation in multi-seam coal exploitation on bedding slopes.

顺倾层状碎裂结构岩质边坡地震动力响应及破坏模式分析

顺倾层状边坡沿软弱带剪切方式破坏是滑坡的主要类型之一。采用块体砌筑斜坡振动台模型,在多维多参数地震动作用下,考虑斜坡不同工况下力学参数弱化的过程,研究了层状碎裂结构岩质边坡的地震动力响应和失稳破坏模式。结果表明:斜坡地震动特性和斜坡地质结构是决定斜坡地震动力稳定性以及破坏模式的决定因素;斜坡水平动力响应具有明显的高程和坡表放大效应,高程对斜坡的垂直动力响应影响较小,地震动放大效应与结构面力学强度、地震波波形、频谱特性等均有一定的关系,正弦波较天然波对坡体放大效应影响更为显著;坡体裂纹依托优势结构面在最弱部位起裂萌生扩展,并向节理面追踪形成蠕滑段和锁固段,节理面强度参数在外界地质营力作用下发生弱化,使潜在滑带出现由后缘向前端搭接贯通的前进式破坏模式和由前端向后缘的后退式破坏模式的分化,滑体也由高位剪出向溃散破坏演变。

含软弱夹层顺层岩质边坡变形-滑动演化过程研究

为研究含软弱夹层顺层岩质边坡的变形、破坏及滑动演化过程,以抚顺西露天矿南帮E1200剖面为研究对象,采用GDEM建立二维数值计算模型,模拟重力作用下边坡的变形、破坏及其沿滑面滑动的演化情况。研究结果表明:抚顺西露天矿南帮为上陡下缓的层状体边坡。在变形破坏阶段边坡整体遵从拉裂-滑移-剪断的变形破坏模式,其中坡顶回填土发生剪切破坏,坡中玄武岩及坡底软弱夹层2处发生滑移-弯曲破坏,坡底油母页岩发生滑移-剪断破坏;潜在滑动面从坡顶沿软弱夹层2向坡底逐步扩展最后贯通;滑动阶段边坡主要沿断层泥-煤接触面向下滑动。

基于弹性薄板理论顺层边坡岩体稳定性分析与实测

为了定量分析顺层岩质边坡变形失稳条件,将层状边坡岩体视为理想的弹性薄板,并充分考虑边坡沿走向长度方向的尺寸,采用能量平衡法综合分析顺层边坡岩体稳定性,推导得出边坡变形失稳判据,确定出边坡滑动段与弯曲变形段计算公式,并将所得结果与传统弹性梁理论分析方法进行对比,结合现场实测数据,证明弹性薄板理论分析方法的准确性与适用性。

碎裂状顺层岩质边坡地震动力响应与破坏模式

西南山区存在着大量碎裂状顺层岩质边坡,在地震作用下极易引发崩塌、滑坡等灾害。为探究碎裂状顺层岩质边坡的动力响应与破坏模式,以西南山区某边坡工程为依托,通过实地调研和参考工程地质资料,对结构面的分布规律进行了详细总结,并通过赤平极射投影对边坡的整体稳定性进行了分析。在此基础上,利用离散元UDEC建立了多组碎裂状顺层岩质边坡模型,通过加载EL–Centro波和Kobe波分析边坡动力特性及破坏模式,并研究了节理参数对位移和加速度响应的敏感性规律。结果表明:坡面位移响应规律呈现先增大再减小的规律,位移响应最大位于M4处;边坡的PGA放大系数呈现高程放大效应,地震波类型会影响PGA的响应规律;地震波穿过强弱风化交界处的结构面时会消耗一定的能量,局部FFT幅值会降低;碎裂状顺层岩质边坡的破坏模式为裂隙扩展–强风化岩体滑移型破坏;节理参数敏感性分析表明,弱风化岩体区域的层理间距对位移的影响最为明显,而强风化节理间距对加速度放大影响最为明显。数值仿真分析较好地揭示了地震作用下碎裂状顺层岩质边坡的动力响应规律和破坏模式,为进一步研究此类边坡的灾变机制和防治提供了有益参考。