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1.
动水驱动型顺层岩质滑坡数量多、灾害频发、危害大, 是滑坡地质灾害领域的研究重点, 但目前对于滑坡启滑机制的认识仍不充分, 滑坡的准确预报还面临巨大挑战。鉴于此, 以含软弱夹层的中倾角顺层岩质滑坡为研究对象, 通过构建理想的单层滑带滑坡物理模型, 开展了一系列动水作用下的滑坡模型试验研究。结果表明, 动水作用下顺层岩质滑坡从开始变形至失稳滑动需经历初始变形、缓慢变形、加速变形和失稳破坏4个阶段, 而各个阶段的演化特征与滑面粗糙度和倾角密切相关。滑面倾角越大或粗糙度越小, 滑坡体从开始变形至失稳滑动所需的时间则越短; 相应地, 坡体加速变形阶段越不明显, 滑坡破坏的突发性越强。滑带内的渗流冲蚀作用会使滑带土中的骨料流失, 导致其抗剪强度降低, 进而引发坡体滑动。与此同时, 上覆坡体的压剪作用以及变形演化过程亦将反过来影响冲蚀强度。基于滑带土黏聚力随水力梯度和冲蚀时间的变化关系, 提出了渗流驱动下滑带土黏聚力演化模型, 可较好地描述滑带土黏聚力的退化过程。滑面粗糙度的存在不仅显著影响了滑带的冲蚀劣化规律, 还改变了滑带不同区域的破坏模式。此外, 通过考虑滑面粗糙度对滑带不同区域破坏模式的影响, 开展了动水多效应关联分析, 建立了滑坡地质体力学分析模型, 实现了动水作用下顺层岩质滑坡动态稳定性的有效评估。本研究成果可为实际动水驱动型顺层岩质滑坡的预测和防治提供理论参考。 相似文献
2.
采空区地表山体侧向变动,不同于一般天然山坡,也与采空区一般上覆岩层的变形破坏有异;它是二者复合机理的效应。本文在分析考察了毗邻电厂的横山顺倾构造山体、剖析了地下采空情况认为:山体侧向变动中,软弱夹层有决定性作用,变动范围、速率和规模与地下采空有关;并利用地质力学模型试验和数值模拟,探索了采动引起山体应力场及变动规律。结果表明,山体岩层的变形、位移、破坏、由直接顶板向地表发展,采空坍陷诱发了软弱夹层的蠕滑,则产生山体侧向滑移;电厂区地表隆起变形是山体侧向滑移挤压地基土的反映。通过现场实际调研、变形观测资料分析与数值模拟和模型试验的对比研究,提出了“坍落拱梁”的成生效应、挤压蠕滑效应、失稳效应;揭露了顺倾构造山体在采空影响下,具有地表、地下的“复合临空面”的“复合应力场”中“复合变动”的“复合机理”;并提出这种山体侧向变动机理的典型地质模式,借以论证山体稳定性。 相似文献
3.
针对2016年5月发生于秭归县西北部的谭家湾滑坡,结合卫星遥感影像、现场勘查资料以及历史资料等多源数据,初步明确了滑坡的影响区域、特征及发生时序;综合采用钻探、槽探、物探等手段,开展室内外相关实验,明确了滑坡区的地层特性以及岩土体物理力学性质指标,通过分析该区裂缝位移及GPS数据,对该边坡的变形机制进行了探讨,并对该区稳定性进行了评价。结果表明:①谭家湾滑坡属于不规则"圈椅形"中型松散层的水库下降型滑坡,滑坡区的地表形态、地质构造及岩性等因素决定了滑坡的形成和发育,库水位和降雨的共同作用激励了滑坡的变形;②滑坡根据时序共分为3级滑体,总体呈现多次、多层、相互影响的演化特点,第三级滑体具有牵引式特征;③滑坡体内地下水位随库水位下降而下降,但下降速率缓于库水位,随之坡体内水力梯度和渗透力显著变大,此时碰到强降雨,将会导致坡体地下水赋存,岩土体软化,加剧滑坡变形,须施加必要的防护措施。④稳定性分析表明,该滑坡现处于临界稳定状态,一旦发生降雨和库水位变化,局部段可能发生失稳滑动。 相似文献
4.
层状反倾岩质边坡是一种常见边坡类型，其变形破坏模式多样、力学机制复杂、影响因素众多。为揭示层状反倾岩质边坡不同临空条件几何特征参数对反倾边坡倾倒变形影响规律，通过3DEC并结合数理统计系统深入研究几何特征参数对倾倒变形影响。研究表明:①反倾边坡具有3个临空面时边坡变形最大，1个临空面时边坡变形最小；②变形随边坡高度、切坡角度增大而增大，随节理面与临空面夹角的增大而减小，随岩层厚度增大先增大后减小；③2个临空面夹角90°时边坡变形最大；④1个、2个临空面时节理倾角60°时位移最大，3个临空面时随节理倾角增大而增大。 相似文献
5.
软硬互层结构的顺层岩质边坡破坏类型复杂、难于防治, 针对此类边坡地质灾害易发、多发的问题, 从坡面角度、岩层倾向及组合形式、节理分布等方面进行了研究。边坡物理模型试验是揭示边坡变形破坏机理的重要手段, 基于相似理论, 以重庆市万州区孙家滑坡为工程依托, 根据滑坡区地质勘探报告设计了室内边坡物理模型试验; 试验通过顶升模型箱模拟重力加载来探究顺层岩质边坡发生破坏时, 前缘坡角和软弱夹层倾角之间的关系; 结合有限元分析软件Plaxis 2D对物理模型进行了多组数值模拟试验, 以验证软硬互层顺层岩质边坡破坏机制。试验结果表明: 对于顺层岩质边坡, 当软弱夹层的倾角在22°左右, 前缘开挖坡角58°左右时, 顺层岩质边坡容易发生滑动, 滑动面为后缘节理面和软弱夹层的贯通面。因此, 顺层岩质边坡稳定性受层面和节理面密度的控制, 当边坡含多层软弱层面时, 易沿层面和后缘节理贯通面发生破坏, 随着软弱面层数增加, 边坡稳定系数逐渐降低。研究成果可以为公路开挖切坡导致的顺层岩质边坡失稳机理研究及其稳定性评价提供理论依据, 为顺层岩质边坡失稳的预测预报提供支撑。 相似文献
6.
水库滑坡变形破坏受其岩土体蠕变特性及环境因素的影响。当滑坡进入加速变形阶段后,变形骤然增大,失稳概率增加。为了研究滑坡岩土体蠕变特性及其稳定性,选取锦屏一级水电站呷爬滑坡为研究对象,采用坡表位移监测曲线分析与室内三轴蠕变试验相结合的方法,建立了Burgers蠕变模型结合FLAC3D软件进行了滑坡稳定性研究。分析坡表位移-时间曲线发现,坡体变形特征与一般滑坡土体的蠕变特征具有相似性,滑带土室内三轴蠕变试验结果表明,滑带土变形可划分为瞬时蠕变、减速蠕变与稳定蠕变3个阶段,同时其瞬时变形量、稳定蠕变速率均随围压以及应力水平的增大而增大。基于滑带土蠕变特性的Burgers蠕变模型的计算结果,对比了常规强度折减法与考虑蠕变的强度折减法的滑坡稳定性系数,计算结果表明呷爬滑坡目前处于稳定状态,在一个计算周期内考虑蠕变的强度折减法较常规强度折减法的稳定性系数下降了0.04,因此,揭示滑坡土体蠕变特性并在此基础上研究其稳定性具有实际意义。 相似文献
7.
Effect of the inclined weak interlayers on the rainfall response of a bedded rock slope 总被引：1，自引：1，他引：0
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 geo-mechanical 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 the superficial 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. 相似文献
8.
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。 相似文献
9.
The stability of soil-rock mixtures(SRMs) that widely distributed in slopes is of significant concern for slope safety evaluation and disaster prevention. The failure behavior of SRM slopes under surface loading conditions was investigated through a series of centrifuge model tests considering various volumetric gravel contents. The displacement field of the slope was determined with image-based displacement system to observe the deformation of the soil and the movement of the block during loading in the tests. The test results showed that the ultimate bearing capacity and the stiffness of SRM slopes increased evidently when the volumetric block content exceeded a threshold value. Moreover, there were more evident slips around the blocks in the SRM slope. The microscopic analysis of the block motion showed that the rotation of the blocks could aggravate the deformation localization to facilitate the development of the slip surface. The high correlation between the rotation of the key blocks and the slope failure indicated that the blocks became the dominant load-bearing medium that influenced the slope failure. The blocks in the sliding body formed a chain to bear the load and change the displacement distribution of the adjacent matrix sand through the block rotation. 相似文献
10.
由于传统搜索方法对岩质边坡滑裂面的确定无法兼顾效率与精度, 如何迅速准确确定潜在滑裂面仍然是个难题。极限平衡法在岩质边坡稳定性分析中备受认可, 采用岩质边坡平面剪切滑动模型, 以滑裂面的倾角来表征潜在滑裂面的位置; 基于极值法, 推导了极限平衡条件下平面剪切破坏型岩质边坡潜在滑裂面的解析解, 并结合香港秀茂坪路边坡对其准确性进行了验证, 进一步对四川宜宾打营盘山公路多级边坡进行了整体稳定性分析。结果表明: 香港秀茂坪边坡采用本文方法确定的边坡潜在滑裂面倾角与实际滑坡倾角基本一致。实际工程应用中, 采用Slide软件中布谷鸟搜索法和模拟退火法两种搜索方法得到的滑裂面倾角分别为38.0°和37.0°, 本解析法所得倾角为34.8°; 选用Janbu法、Morgenstern-Price法和Sarma法分别计算对应的稳定系数, 结果均为1.04左右, 本文所得稳定系数为1.15, 可见本文方法所得结果基本准确。通过参数敏感性分析发现, 随着黏聚力的增加, 边坡滑裂面倾角越来越小, 稳定系数也随之增加; 而当内摩擦角增大时, 边坡滑裂面倾角和稳定系数也随之增大。 相似文献
11.
斜坡变形受众多因子综合控制, 不同因子的敏感性与作用规律在变形过程中差异明显。以湖北省阳新县顺层基岩滑坡为研究对象, 通过正交试验结合离散元数值模拟的方法, 研究多个影响因子对应顺层滑坡变形的敏感性并确立主导因素, 随后基于响应面拟合主导因素与滑坡不同部位变形程度间的量化关系, 揭示主导因素交互作用对滑坡变形破坏模式的影响规律。结果表明, 在研究区内坡度与岩层倾角分别为影响顺层滑坡变形的主导与次主导因素, 滑坡的变形破坏模式受控于二者的交互作用。在中-陡倾顺层滑坡中, 当坡度小于岩层倾角时, 滑坡变形主要集中在坡顶, 且变形程度随岩层倾角的增加而增大, 表现出滑移-弯曲的变形破坏模式; 在缓倾顺层滑坡中, 当坡度大于岩层倾角时, 滑坡坡脚位移较坡顶显著, 其坡脚变形程度随坡度的增加而增大, 以滑移-拉裂变形为主。研究成果可为该类滑坡的防治工作提供参考。 相似文献
12.
滑坡变形演化特征一直是滑坡灾害预测与防治领域急需解决的关键问题, 但对于多层滑带滑坡的变形演化特征却少有研究。以物理模型试验为手段建立了三层滑带滑坡物理试验模型, 完成了多层滑带滑坡变形演化全过程的模拟。基于PIV技术获取坡表位移数据, 通过柔性测斜仪监测滑坡深部位移, 同时布设土压力盒获取滑坡内部土压力的变化情况, 实现了多层滑带滑坡演化过程多参量数据分析。试验结果表明, 多层滑带滑坡破坏过程可分为初始、等速、加速和破坏4个阶段。不同破坏阶段滑坡的主要变形区域不同, 下层滑体受到上层滑体牵引作用, 在重力和推力作用下滑坡变形逐渐向浅层发展。变形过程中滑坡应力逐渐向滑带集中, 滑坡推力沿埋深方向呈多级梯形分布。加速变形阶段滑带处应力迅速增大, 滑坡体内产生多层应力集中带, 滑带位置推力变化与滑坡位移显著相关。 相似文献
13.
在持续降雨或开挖卸荷作用下, 土体的强度指标会发生劣化, 但现今采用的边坡稳定性计算大多直接将其视为一个常数。为接近真实的边坡失稳破坏模式, 基于瑞典条分法以及一阶线性应变软化机制, 提出了一种边坡渐进破坏分析新方法, 推导出应变软化型边坡极限平衡表达式, 并获得了各破坏进度下边坡的安全系数。通过对模拟算例进行分析, 证明了条分-软化法的可靠性, 且计算结果表明渐进破坏过程中安全系数不仅取决于边坡的破坏方式与强度参数, 还与岩土体的软化模量密切相关。同时, 通过与滑坡实际案例的对比验算, 证实其强度指标存在不同的衰减系数, 即黏聚力的衰减系数大于摩擦角。从理论到应用, 最终获得的条分-软化法, 不仅考虑了岩土体的强度劣化效应以及滑动面的渐进发展, 还能有效地服务于实际工程背景下边坡的稳定性分析, 可以为滑坡的预防与治理提供指导建议。 相似文献
14.
锚索抗滑桩是滑坡的主要支护结构之一。目前, 软硬相间地层条件下锚索抗滑桩的受力与变形特征尚缺乏系统研究。以软硬相间地层为地质背景, 基于自主研发的柔性测斜仪和自动加载系统, 构建了锚索抗滑桩加固滑坡物理模型试验系统, 开展了锚索抗滑桩加固滑坡的物理模型试验, 揭示了推力不断增加过程中抗滑桩、锚索和滑体的变形与受力特征, 对比研究了布锚方式对桩-锚受力与变形的影响规律, 通过数值模拟的方法分析了软硬相间地层对锚索抗滑桩的影响机理, 并以双锚点抗滑桩为例进行了理论分析。研究结果表明: ①在滑坡-锚索抗滑桩体系中, 桩身各点位移和滑体深部位移均随桩身深度的增加而减小, 滑体后部位移速率大于中部, 且滑体位移速率大于桩身位移速率; ②单锚点抗滑桩的桩-锚推力分担比经历了4个阶段的变化, 趋于稳定时桩-锚推力分担比约为9∶1, 锚索拉力作用下桩身弯矩呈"S"型分布, 正负弯矩非对称; ③锚固角度越大, 锚索拉力的增速越大, 不同锚固角度对桩身内力值的影响主要体现在受荷段; ④多锚点抗滑桩结构的锚索分担更多的推力, 与单锚点抗滑桩相比, 双锚点与三锚点抗滑桩的最大桩身弯矩分别减小了22.41%和40.55%;⑤与均质地层相比, 软硬相间地层中软、硬岩交界面处基岩应力发生突变, 不同软岩厚度比和桩底是否嵌入硬岩, 均对锚索拉力和桩-岩之间的相互作用有不同程度的影响; 其次, 双锚点抗滑桩内力的理论值与试验结果较为接近。本研究成果可为软硬相间地层中锚索抗滑桩加固滑坡工程的优化设计提供依据。 相似文献
15.
论述了BDS/GPS双系统组合下的单频单历元阻尼LAMBDA算法原理,并基于该算法实现一种实时远程变形监测系统。以理县某边坡变形监测应用为例,比较了GPS、BDS及其组合系统下的观测条件和阻尼LAMBDA算法定位效果：BDS的观测卫星数多于GPS,PDOP值相较于GPS也更加稳定;BDS单历元解标准差在N、E、U方向上分别为0.40 cm、0.31 cm、1.00 cm,优于GPS的0.61 cm、0.40 cm、1.74 cm。长期实验结果表明,在我国南部边坡监测中,BDS相比GPS具有一定优势。理县边坡23个月内位移量显著,3个监测站平均位移在N、E、U方向上分别达到8.70 cm、43.63 cm、18.03 cm。强降雨是引起土质山体滑坡的主要因素,使用累积降雨量和累积位移量建立线型回归模型,线性相关系数在0.98以上。在边坡监测中,可将实时的位移数据和降雨数据作为滑坡预警的重要依据。 相似文献
16.
Modelling the flexural buckling failure of stratified rock slopes based on the multilayer beam model
The buckling failure of stratified rock slopes intersected by a set of steep discontinuities that are approximately parallel to the slope surface is frequently encountered while constructing railways and roadways in mountainous areas. In this study, an analytical approach based on the energy equilibrium principle is presented to solve the flexural buckling stability of stratified rock slopes within the framework of multilayer beam theory. The generalized HoekBrown failure criterion is introduced to reflect the influences of slope size(scale effects) on the buckling stability. Subsequently, numerical and physical modellings from previous literatures are employed to validate the proposed approach. Furthermore, a practical case of Bawang Mountain landslide is also used for the comparative analysis. The study shows that the present analytical approach is capable to provide a more reasonable assessment for the buckling failure of stratified rock slopes, compared with several existing analytical approaches. Finally, a detailed parametric study is implemented, and the results indicate that the effects of rock strength, rock deformation modulus, geological strength index, layer thickness and disturbance degree of rock mass on the buckling failure of stratified rock slopes are more significant than that of rock type and slope angle. 相似文献
17.
A new small-scale geotechnical physical model in 1-g and unconfined condition, combining the transparent soil, close-range photogrammetry and particle image velocimetry (PIV), was employed, which provides a non-intrusively internal deformation measurement approach to monitor the internal deformation of soil caused by expanded-base pile jacking with casing. The transparent soil was made of fused quartz and its refractive index matched blended oil, adding reflective particles (glass beads). Close-range photogrammetry was employed to record the images of the process of casing jacking and extraction in transparent soil, allowing the use of Matlab-based Geo-PIV to figure out the displacement field converted from image space to object space. Analysis of test results indicates that the maximum displacement caused by casing jacking for expanded-conical-base pile is decreased by 29% compared with that for expanded-flat-base pile. The main movement happens at the early stage of casing extraction. The maximum displacement caused by casing extraction for the conical base is about 43% of that for the flat base, while the affected zone caused by casing extraction for the conical base accounts for about 1/3 of that for the flat base. The contraction for horizontal displacements tends to decrease with the depth increasing. By contrast, the contraction under pile base decreases with the increasing of displacement. The displacements generated by jacking a conventional pile having a diameter equal to the casing diameter of the expanded-base pile were comparable to the net displacement taking place due to expanded-base pile installation for the conical base pile. 相似文献
18.
Mountain hazards with large masses of rock blocks in motion – such as rock falls, avalanches and landslides – threaten human lives and structures. Dynamic fragmentation is a common phenomenon during the movement process of rock blocks in rock avalanche, due to the high velocity and impacts against obstructions. In view of the energy consumption theory for brittle rock fragmentation proposed by Bond, which relates energy to size reduction, a theoretical model is proposed to estimate the average fragment size for a moving rock block when it impacts against an obstruction. Then, different forms of motion are studied, with various drop heights and slope angles for the moving rock block. The calculated results reveal that the average fragment size decreases as the drop height increases, whether for free-fall or for a sliding or rolling rock block, and the decline in size is rapid for low heights and slow for increasing heights in the corresponding curves. Moreover, the average fragment size also decreases as the slope angle increases for a slidingrock block. In addition, a rolling rock block has a higher degree of fragmentation than a sliding rock block, even for the same slope angle and block volume. Finally, to compare with others' results, the approximate number of fragments is estimated for each calculated example, and the results show that the proposed model is applicable to a relatively isotropic moving rock block. 相似文献
19.
The failure of slope is a progressive process, and the whole sliding surface is caused by the gradual softening of soil strength of the potential sliding surface. From this viewpoint, a local dynamic strength reduction method is proposed to capture the progressive failure of slope. This method can calculate the warning deformation of landslide in this study. Only strength parameters of the yielded zone of landslide will be reduced by using the method. Through continuous local reduction of the strength parameters of the yielded zone, the potential sliding surface developed gradually and evolved to breakthrough finally. The result shows that the proposed method can simulate the progressive failure of slope truly. The yielded zone and deformation of landslide obtained by the method are smaller than those of overall strength reduction method. The warning deformation of landslide can be obtained by using the local dynamic strength reduction method which is based on the softening characteristics of the sliding surface. 相似文献
20.
The motion forms (deformation) of the sliding soil along the slope include inviscid particle flow, viscous particle flow, and mass sliding. The motion forms were mainly influenced by the mechanical properties of the viscous mud medium filling. The effect of the medium filling on the motion forms of the sliding soil is worth discussing. The sliding soil can be seen as the mixture which is composed of the medium filling and coarse particles. The Chengdu clay with different moisture contents were selected as the medium filling. Their mechanical parameters were experimentally measured for simulating the moving process of the sliding soil. Different motion forms of the sliding soil were numerical simulated based on PFC3D by changing the specific mechanical parameters. The mechanical parameters of the Chengdu clay are experimentally determined. The numerical results show that with the moisture content of the filling slurry medium in the range of >302%, 101%~182%, and <80%, the motion form of the sliding soil belongs to the inviscid particles flow (similar with the sliding sand), viscous particles flow (seen as the viscous flows); and mass sliding (seen as the block sliding along the slope surface), respectively. 相似文献