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高速远程滑坡-碎屑流具有速度快、滑程远、冲击破坏力强等特点,是一种危害性极大的地质灾害,往往会造成严重的生命财产损失。汶川地震后,国内学者对高速远程滑坡-碎屑流的研究取得了大量前瞻性成果,但由于此类滑坡自身的复杂性,目前为止尚未取得公认的研究成果。为了进一步揭示高速远程-碎屑流效应机理,本文以汶川地震触发的青川东河口滑坡-碎屑流为例,通过滑坡动力分析软件DAN-W分别建立了摩擦模型、Voellmy模型和F-V等3种不同的滑坡数值模型,对东河口滑坡-碎屑流的运动距离、不同时刻运动速度特性、堆积物分布规律及滑坡堆积体积进行了模拟,同时对滑坡运动时间进行了估算。模拟结果表明:根据高速远程滑坡-碎屑流不同运动阶段选择不同的流变模型分析的结果更加合理。摩擦流变模型对运动距离的模拟结果小于滑坡的实际滑程,适于模拟滑体整体性好的启程和近程运动阶段; Voellmy 流变模型对滑体的运动距离模拟效果很好,但对速度的分析结果偏大,适合模拟滑坡远程碎屑流运动阶段; F-V双流变模型对滑坡运动特性模拟效果最佳,并给出了选取东河口滑坡-碎屑流数值模型的最佳流变参数,摩擦角φ=18°,摩擦系数μ=0.1,湍流系数ξ=400m·s-2。 相似文献
2.
近年,浅层滑坡、泥石流灾害发生在植被良好区的频率较大。一方面,植被对灾害的抑制或促进作用还有待进一步深入认知;另一方面,目前灾害风险源评估方法中较少考虑植被对斜坡稳定性的影响。为探究不同植被类型对浅层斜坡的稳定性影响,本文以大渡河流域作为研究区,通过对区域坡度、坡向及植被等数据提取和坡面划分,采用有限差分数值计算方法,对区域内划分的40 000余个斜坡进行了稳定性计算,获取了该区域不同植被覆被条件下浅层斜坡的稳定性系数,探究在不同植被覆被条件下浅层不稳定斜坡的分布规律。结果表明随着坡度增加不同植被类型稳定斜坡数下降程度不一,总体上乔木林覆被斜坡稳定性较差,灌丛次之,草甸较好。进一步对区域内潜在浅层不稳定斜坡的植被类型和坡度进行统计分析,发现不同植被类型覆被条件下不稳定斜坡的坡度分布具有正态分布特征,基于建立的3种不同植被类型不稳定斜坡发育概率与坡度间的函数关系,确定出不同植被类型不稳定斜坡发育概率最高的坡度区间：乔木林为26.0°～37.0°,灌丛为28.0°～39.0°,草甸为31.0°～39.0°。本研究可以为流域尺度滑坡、泥石流等地质灾害的防治与规划提供依据,为良好植被区灾害风险... 相似文献
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夏万云 《中国地质灾害与防治学报》2022,33(1):99-106
黄土坡面侵蚀特性研究对于铁路边坡及路基防护具有重要的意义。通过银西高铁董志塬段某路基护坡坡面冲刷试验,获得了不同冲刷历时、冲刷流量、坡度等条件下的坡面冲刷结果,并对坡面流水动力学特性、坡面产沙规律、坡面产沙机理进行了分析,得出以下结论:（1）坡顶和坡底比坡面中部更易受侵蚀;30°～60°斜坡在较小的冲刷强度下也能产生较明显的侵蚀沟,宜采取45°左右的多级矮坡来减弱侵蚀强度。（2）坡面流水动力学特性分析表明,试验工况水流主要处于过渡流区;平均流速与冲刷流量、坡度呈幂函数关系;达西阻力系数与冲刷流量、坡度呈负相关,且与雷诺数相关性较低。（3）平均含沙量随冲刷流量与坡度的增大而增大,随历时近似线性增加,约20 min以后,含沙量基本稳定,此过程为坡面沟道发展阶段。（4）坡面侵蚀产沙量与侵蚀切应力、有效水流功率都呈正相关,与前者近似呈线性增大关系,而与后者近似呈幂函数关系。 相似文献
4.
本文针对受红椿坝-曾家坝断裂控制的陕西省安康市岚皋县柳家坡滑坡,在现场调查分析的基础上,采用Midas/GTS软件对其形成机理进行了三维数值模拟研究。模拟结果表明,断裂对该滑坡的发生起着控制性的作用,岩土体的性质决定了该滑坡的类型,而水和人类工程活动触发了该滑坡的发生。得到柳家坡滑坡的变形破坏模式为:坡体前缘向前运动,西侧断层强烈破碎带通过处侧壁剪切破坏,坡体后缘产生张拉裂缝,从而带动东侧坡体的变形破坏。由于坡体前缘为修建公路开挖的临空面,坡脚处缺失支撑,诱发了滑坡的发生。柳家坡滑坡形成机理的模拟结果可为日后相似条件下滑坡的防治提供一定的借鉴。 相似文献
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通过室内模拟冲刷试验系统研究了3°~30°坡度范围内坡面径流的侵蚀动力及产沙特征,分析了坡面径流能耗与径流侵蚀产沙之间的关系。结果表明,坡面径流平均流速随坡度和流量的增加而增大,流速与坡度和流量之间存在指数函数关系,坡度对流速的影响大于流量。在3°~21°坡度范围内,坡面径流单宽能耗随坡度的增加而增加,当坡度超过21°时,径流能耗随坡度的增加而降低。坡度对侵蚀产沙的影响也有类似的现象,在3°~21°坡度范围内,坡面径流平均单宽输沙率随坡度的增加而增大,当坡度达到临界极值21°和24°后,坡面径流平均输沙率随坡度增加而减小;在整个试验坡度范围内,径流平均单宽输沙率随流量的增大而增大;流量对坡面径流平均单宽输沙率的影响大于坡度。坡面径流平均单宽输沙率和单宽径流能耗之间存在明显的线性关系,其临界单宽径流能耗随坡度的增加而增加,土壤可蚀性参数随坡度的变化在10.368~30.366的范围变化,试验的土壤可蚀性的平均值为14.61。 相似文献
6.
通过室内模拟试验,在坡度为3°和9°、流量为20和60L/min条件下研究了不同浓度(0～350kg/m3)含沙水流流经草地的泥沙沉积过程及其水力学特性。结果表明,坡面泥沙沉积量随含沙量的增加而增大,3°时泥沙沉积率与含沙量呈正相关,而9°时沉积率与含沙量呈反势。坡度对泥沙沉积影响显著,而在相同坡度条件下,两种流量试验的泥沙沉积量无明显差异。相同坡面坡上部位流速小于坡下部位,且含沙量对坡面流速影响较小。在相同坡度和流量条件下,水流雷诺数随含沙量的增大而减小。3°时水流阻力系数和曼宁糙率均随含沙量的增加而增大,而9°时含沙量对阻力影响不明显,因此在土壤侵蚀较严重地区进行坡面水文过程演算时需考虑含沙量对缓坡糙率的影响。 相似文献
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8.
重庆小南海滑坡形成机制离散元模拟分析 总被引：1，自引：0，他引：1
重庆小南海滑坡是烈度相对较低地区发生的地震高位滑坡,其成因一直令人费解。基于重庆黔江小南海相关研究资料,通过对复原的小南海坡体进行失稳分析,计算得出使岩体产生崩滑破坏的地震力临界条件,即只有当地震波地形放大后滑坡才能启动。为了进一步验证计算所得的结论,运用UDEC软件建立小南海典型二维场地模型,施加相应的地震力对坡体失稳崩滑的全过程进行模拟,以研究地震作用下地形放大效应触发具平行坡面陡倾控制性结构面的高位岩质斜坡地震机理。研究结果表明,在地震波传播过程中,具平行坡面陡倾控制性结构面的高陡突出地形对地震波有明显的放大作用。该坡体运动模式为：峰值加速度放大-增加的振幅迫使岩体顺平行坡面陡倾控制性结构面迅速拉裂-沿缓倾层面滑移-高速脱离滑源区-巨大的势能和动能驱动坡体做长距离运动,其间伴随解体、颗粒间相互碰撞、铲刮作用,具有二相甚至三相流体性质。分析揭示地震力作用下斜坡体中质点加速度具有地形放大效应。对比结构面监测点和基岩监测点加速度放大系数,表明,滑坡启动时具有较大的加速度,当遇到平行坡面的不连续结构面时,斜坡动力响应强烈,最终导致坡体失稳。 相似文献
9.
通过模型实验,探讨了松散土坡3种不同结构特征条件下(均匀坡体(坡体物料均匀混合)、平行坡体(土层成层且层面与滑面平行)和斜交坡体(土层成层且层面与滑面斜交))形成滑坡堰塞体的动力过程和堆积特征,通过分区域取样及三维扫描技术研究了堰塞体的物质分布规律与形态特征。研究结果表明:堰塞体堆积特征与坡体特征存在紧密联系,堰塞体纵向(沿主沟道方向)和横向(沿滑坡运动方向)上的物质分布与坡体纵向和横向的物质分布特征基本对应;在垂向(表层到底部)上,由于不同坡体条件下滑坡的动力过程和机理不同,从而导致堰塞体堆积特征存在一定区别。均匀坡体和平行坡体呈整体启动模式,运动过程中物料间存在垂向渗透和交换作用,导致堰塞体物质在垂向上呈明显的上粗下细反粒序分布特征,堰塞体横剖面多呈平坦型和倾斜型。斜交坡体呈分层启动模式,运动堆积过程中保持原有层序,粗、细颗粒先后启动条件下颗粒间存在推挤、爬升和水平渗透作用,使得堰塞体更加密实且垂向上也呈现反粒序分布特征,横剖面多呈起伏型。本研究为滑坡堰塞体稳定性快速评估和复原滑坡初始状态提供依据。 相似文献
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以苏州清明山滑坡为例,采用颗粒流软件PFC2D建立了滑坡体的二维数值模型,通过监测坡体表面不同部位的位移和应力变化情况,对边坡滑动的演化过程和破坏机理进行了详细的分析。数值试验结果显示该顺层边坡的失稳是一个渐进的过程,首先沿靠近坡面的一组软弱结构面发生滑动,下方滑床岩体在上覆滑体的挤压和摩擦作用下发生破碎,使滑动不断向深处发展。在前期形成的临空面和软弱结构面的共同影响下,滑坡后缘岩体产生一组近乎垂直的拉裂面,该竖向破裂面的存在有利于雨水入渗,进一步降低软弱夹层的抗剪强度参数,从而使边坡由小范围的崩塌破坏转为大范围的滑动破坏,属滑移-压致拉裂型滑坡。清明山滑坡滑移机理的研究对后续地质灾害治理有重要意义。 相似文献
11.
合理的流变参数选取对准确刻画泥石流、高速远程滑坡运动过程和动力行为至关重要。本研究基于三维连续介质动态数值模型,构建Voellmy流变模型,结合方差分析方法,比较了不同流变参数对泥石流运动行为的影响程度。结果表明:动力底摩擦角和湍流系数均会对泥石流与高速远程滑坡的动力特征产生一定的影响,但影响程度各异。较大的动力底摩擦角会产生更大、更快的能量耗散过程,使得运动过程整体滞后;较高的湍流系数增加了流体层之间的动量交换强度,具有较大的与周围界质混合的能力,对周围介质的卷吸作用增大。物源区体积（湍流系数）在一定程度上仅影响泥石流运动速度,对致灾范围和规模影响作用不大。沟道下垫面情况、颗粒物组成、孔隙水压力（底摩擦角）与灾害体流速、移动距离和堆积区体积、面积关系很密切,在很大程度上影响泥石流、滑坡强度,致灾范围和规模。研究成果以期为流变参数选取提供很好的借鉴方法,也为地质灾害防治提供一定的技术参考。 相似文献
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Comparison of numerical models of two debris flows in the Cortina d’ Ampezzo area,Dolomites, Italy 总被引：2，自引：0，他引：2
The accurate prediction of runout distances, velocities and the knowledge of flow rheology can reduce the casualties and property
damage produced by debris flows, providing a means to delineate hazard areas, to estimate hazard intensities for input into
risk studies and to provide parameters for the design of protective measures. The application of most of models that describe
the propagation and deposition of debris flow requires detailed topography, rheological and hydrological data that are not
always available for the debris-flow hazard delineation and estimation. In the Cortina d’Ampezzo area, Eastern Dolomites,
Italy, most of the slope instabilities are represented by debris flows; 325 debris-flow prone watersheds have been mapped
in the geomorphological hazard map of this area. We compared the results of simulations of two well-documented debris flows
in the Cortina d’Ampezzo area, carried on with two different single-phase, non-Newtonian models, the one-dimensional DAN-W
and the two-dimensional FLO-2D, to test the possibility to simulate the dynamic behaviour of a debris flow with a model using
a limited range of input parameters. FLO-2D model creates a more accurate representation of the hazard area in terms of flooded
area, but the results in terms of runout distances and deposits thickness are similar to DAN-W results. Using DAN-W, the most
appropriate rheology to describe the debris-flow behaviour is the Voellmy model. When detailed topographical, rheological
and hydrological data are not available, DAN-W, which requires less detailed data, is a valuable tool to predict debris-flow
hazard. Parameters obtained through back-analysis with both models can be applied to predict hazard in other areas characterized
by similar geology, morphology and climate. 相似文献
13.
Although most cut slopes in Ohio consist of inter-layered, sub-horizontal units of hard and soft sedimentary rocks (sandstone, limestone, dolostone, shale, claystone, mudstone), slopes consisting of relatively thick hard rock units are not uncommon. Design of stable cut slopes in hard rock units needs to consider rock mass strength and orientation of discontinuities with respect to slope face. Results of kinematic stability analyses show that hard-rock cut slopes are less likely to have conventional plane and wedge failures, caused by unfavorable orientation of discontinuities. The main cause of failure is identified to be the undercutting-induced toppling, which is not amenable to traditional kinematic or rock mass strength-based analyses. Therefore, to recommend a suitable slope angle, numerical models, using UDEC software, were employed to study how various slope angles affect the process of undercutting-induced toppling failures. The UDEC models showed a slope angle of 45° (1H:1 V) to be the most stable angle. However, a 63° (0.5H:1 V) slope angle can significantly reduce the potential for such failures and is therefore more appropriate than the widely used angle of 76° (0.25H:1 V). 相似文献
14.
我国西南高山峡谷地区,常发生高位岩质斜坡失稳,形成碎屑流,造成巨大人员伤亡与经济财产损失。目前存在着许多关于岩质滑坡的研究理论和物理模型,但这些理论与模型都忽略了岩体结构这一属性,然而对岩质滑坡而言,岩体的结构特征不仅控制着斜坡变形失稳模式,同样影响失稳后滑体碎屑化运动过程,甚至最终的危害范围。因此,文章使用离散元数值模拟方法,通过模拟不同结构面强度、结构面密度、结构面方向和岩块强度下岩质滑坡碎屑化运动过程,研究了不同源区岩体结构对岩质滑坡破碎特征、运动形式和运动距离的影响规律及影响机制。研究结果如下:（1）质心运动距离随结构面强度增大而增大,结构面抗拉强度提升10倍,质心运动距离增加3%;（2）结构面密度的增加使得块体破碎率随之增加,但运动距离和分布面积都呈下降趋势;（3）水平向结构面岩体的前缘运动距离和质心运动距离与其他方向结构面工况相比均降低10%左右,分布面积则缩减接近30%,破碎率最大;（4）随着岩块强度增加,破碎率降低,分布面积最终缩减40%,完整块体工况运动距离最终增大15%左右。结果有助于进一步理解岩质滑坡动力学过程,指导山区防灾减灾工作。 相似文献
15.
Nikhil Nedumpallile Vasu Seung-Rae Lee Deuk-Hwan Lee Joonyoung Park Byung-Gon Chae 《Landslides》2018,15(8):1523-1539
The predictive hazard analysis at a detailed scale for debris flow runout analysis can be improved significantly through reliable estimation of the input parameters. In this study, a method for database establishment of input parameters at a site-specific scale was laid out for the predictive-based debris flow hazard assessment under extreme rainfall. The adoption of the DAN-3D code necessitated the estimation of three main input parameters: initial volume, bulk basal frictional angle, and growth rate. The initial volume was assessed using a 3D coupled finite element seepage and limit equilibrium-based slope stability analysis. An artificial neural network-based model was developed using 27 debris flow events for predicting the basal bulk frictional angle and consisted of eight factors: plan curvature, profile curvature, percentage of fine content, D50, initial unit weight, initial volume, relative relief ratio, and channel length. Finally, the growth rate was estimated using the previously assessed initial volume, soil depth, and the approximate runout length. The proposed method was validated by application to the Raemian slope in the Woomyeon mountain region, Seoul, for the extreme rainfall event of 27 July 2011. The analysis yielded a final volume of 53,067.9 m3, a velocity upon arrival on the road of 26.81 m/s, and an approximately 0.5-m debris thickness concentrated near the Raemian apartments. The comparison of the predicted debris flow path and debris flow velocity with the actual event demonstrates good similarity and provides a conservative estimate of the volume. This study therefore illustrates the importance of an input parameter database in providing a reliable debris flow runout hazard assessment. 相似文献
16.
高压水射流技术具有工作介质来源广泛与环保等优点,能够用于海底天然气水合物储层破碎。本文运用LS-DYNA有限元程序对淹没状态下高压水射流对海洋天然气水合物沉积物破碎过程进行数值模拟,研究了射流速度、喷嘴直径、靶距、入射角度四项关键参数对含水合物沉积物冲蚀体积的影响,得出以下主要结论：含水合物沉积物产生破碎需要满足射流速度大于临界流速;随着射流速度的增加冲蚀体积逐渐增大;喷嘴直径的增加会导致沉积物径向冲蚀体积的增大,从而使总体冲蚀体积增大;靶距的增加会使水射流在水域运动过程中能量损失增大,导致冲蚀体积的减小;在喷嘴入射角度增大过程中冲蚀体积将会先增大后减小最后趋于稳定,当入射角度为10°时冲蚀体积能够达到最大值。 相似文献
17.
Empirical Relationships for Debris Flows 总被引：40，自引：10，他引：30
The assessment of the debris flow hazard potential has to rely on semi-quantitative methods. Due to the complexity of the debris-flow process, numerical simulation models of debris flows are still limited with regard to practical applications. Thus, an overview is given of empirical relationships that can be used to estimate the most important parameters of debris-flow behavior. In a possible procedure, an assessment of a maximum debris-flow volume may be followed by estimates of the peak discharge, the mean flow velocity, the total travel distance, and the runout distance on the fan. The applicability of several empirical equations is compared with available field and laboratory data, and scaling considerations are used to discuss the variability of the parameters over a large range of values. Some recommendations are made with regard to the application of the presented relationships by practicing engineers, apart from advocating field reconnaissance and searching for historic events wherever possible. 相似文献
18.
Armelle Decaulne 《Natural Hazards》2007,41(1):81-98
In the fjords of north-western Iceland, snow-avalanche and debris-flow hazards threaten 65% of the inhabitants. In this area,
both historical and geomorphological evidences clearly demonstrate the recurrent danger from the steep slopes. Hazard vulnerability
has increased during the last century, in connection with the population development of the Westfjords. Two snow-avalanche
disasters during 1995 (in which 34 people were killed in two villages) prompted efforts to both mitigate and prevent future
snow-avalanche and debris-flow activity. Research (qualitative and quantitative) on process characteristics describes prone
terrain, runout distance, process behaviour along the slope, morphometric properties of the deposits and triggering factors.
Acceptable risk, hazard and risk zoning are clearly defined by official regulations. Evacuation plans are determined from
statistical characterisation of the risk and dynamic numerical modelling. To enhance the risk reduction, permanent and temporary
measures aim to control the processes and to protect the population. 相似文献
19.
地震诱发山体崩塌常形成巨大的灾害,特定地形地质条件下山体地震动力响应特性及破坏机制研究是工程地质的重要难题。本文以秦岭地区具代表性的翠华山甘湫池花岗岩崩塌为研究对象,制作有效反映花岗岩工程地质结构的试验模型,开展大型振动台试验,研究山体地震动力响应规律和崩塌变形破坏机制。试验发现,边坡内部加速度放大系数随激振强度的增加呈现出显著的三阶段变化趋势;水平加速度响应呈现出随高程的增加而单调增大的特征,而竖直加速度响应随着高程的增加出现先增加后减小再增加的波动变化特征;边坡的固有频率变化曲线可以分为3个阶段,整体呈现下降的趋势,表明边坡动力特性发生变化;破坏后的边坡可以分为2个区域:后缘启动区和崩塌堆积区。边坡在地震激振作用下的破坏过程为地震波激振输入→坡体后缘形成拉张裂缝→裂缝向下扩展贯通→不稳定坡体滑动→堆积坡脚。反演了山体破坏的4个阶段:振动致裂阶段、高速启动阶段、撞击减速阶段和堆积阶段,结果与现场工程地质调查分析十分一致。研究翠华山甘湫池花岗岩崩塌的发育特征、成因机理和演化过程,研究成果对揭示秦岭北缘乃至秦岭地区崩塌形成机制、发育规律和灾害有效防控、地质遗迹开发和保护具有重要意义。 相似文献
20.
Debris-flow simulations on Cheekye River, British Columbia 总被引：4，自引：4，他引：0
Cheekye River fan is the best-studied fan complex in Canada. The desire to develop portions of the fan with urban housing triggered a series of studies to estimate debris-flow risk to future residents. A recent study (Jakob and Friele 2010) provided debris-flow frequency-volume and frequency-discharge data, spanning 20-year to 10,000-year return periods that form the basis for modeling of debris flows on Cheekye River. The numerical computer model FLO-2D was chosen as a modelling tool to predict likely flow paths and to estimate debris-flow intensities for a spectrum of debris-flow return periods. The model is calibrated with the so-called Garbage Dump debris flow that occurred some 900 years ago. Field evidence suggests that the Garbage Dump debris flow has a viscous flow phase that deposited a steep-sided debris plug high in organics in centre fan, which then deflected a low-viscosity afterflow that travelled to Squamish River with slowly diminishing flow depths. The realization of a two-phase flow led to a modelling approach in which the debris-flow hydrograph was split into a high viscosity and low viscosity phase that were modelled in chronologic sequence as two separate and independent modelling runs. A perfect simulation of the Garbage Dump debris flow with modelling is not possible because the exact topography at the time of the event is, to some degree, speculative. However, runout distance, debris deposition and deposit thickness are well known and serve as a good basis for calibration. Predictive analyses using the calibrated model parameters suggest that, under existing conditions, debris flows exceeding a 50-year return period are likely to avulse onto the southern fan sector, thereby damaging existing development and infrastructure. Debris flows of several thousand years return period would inundate large portions of the fan, sever Highway 99, CN Rail, and the Squamish Valley road and would impact existing housing development on the fan. These observations suggest a need for debris-flow mitigation for existing and future development alike. 相似文献