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用直线和曲线滑面两种模型，模拟预应力锚索加固含有水平软弱层的高陡边坡的潜在滑动面，通过对锚索加固的力学机理分析来阐述预应力在滑动面主滑方向上产生分力的原因。从锚索受力角度上对锚索倾角的取值范围进行探讨，结合实际造孔过程有不同程度的孔斜或弯曲以及获取较好的锚固灌浆效果，就仰角锚固和俯角锚固两种锚固条件分别得出锚索倾角的取值范围，并以此来判定锚索的预应力是否会在滑动面走向方向上产生不利于坡体稳定的下滑力。 相似文献
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Landslide-prone slopes in earthquake-affected areas commonly feature heterogeneity and high permeability due to the presence of cracks and fissures that were caused by ground shaking. Landslide reactivation in heterogeneous slope may be affected by preferential flow that was commonly occurred under heavy rainfall. Current hydro-mechanical models that are based on a single-permeability model consider soil as a homogeneous continuum, which, however, cannot explicitly represent the hydraulic properties of heterogeneous soil. The present study adopted a dual-permeability model, using two Darcy-Richards equations to simulate the infiltration processes in both matrix and preferential flow domains. The hydrological results were integrated with an infinite slope stability approach, attempting to investigate the hydro-mechanical behavior. A coarse-textured unstable slope in an earthquake-affected area was chosen for conducting artificial rainfall experiment, and in the experiment slope, failure was triggered several times under heavy rainfall. The simulated hydro-mechanical results of both single- and dual-permeability model were compared with the measurements, including soil moisture content, pore water pressure, and slope stability conditions. Under high-intensity rainfall, the measured soil moisture and pore water pressure at 1-m depth showed faster hydrological response than its simulations, which can be regarded as a typical evidence of preferential flow. We found the dual-permeability model substantially improved the quantification of hydro-mechanical processes. Such improvement could assist in obtaining more reliable landslide-triggering predication. In the light of the implementation of a dual-permeability model for slope stability analysis, a more flexible and robust early warning system for shallow landslides hazard in coarse-textured slopes could be provided. 相似文献
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为进一步探明银洞子沟物源区坡面物源启动机理与降雨的相关性,在进行详细的现场考察与工程勘察工作后选取了典型模型体,并采用20余组人工降雨物理试验方法将降雨强度与坡度设为控制变量,研究了4种坡形、5种雨强条件下,坡面松散物源的失稳机制及破坏模式。试验结果揭示了地表变形与地下物理力学参数变化的定量响应关系,并基于试验发生破坏的临界雨量,建立了银洞子沟传统I-D预警模型。之后提炼可靠预警参数(坡度、深部体积含水率),通过数学回归分析方法并采用Exponential模型,得出IGD、IGM多参数新型预警判别式,实现了传统I-D模型的有效修正,并具一定的可靠性和实用价值。 相似文献
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Coseismic deposits are easily transported outside of valleys, thereby inflicting damage through debris flows or aggregating and elevating riverbeds in the fluvial network. The evolution of coseismic deposits is crucial for predicting the sediment transport capacity and export time for managing postseismic geohazards; however, this evolution remains unclear. In this study, the spatiotemporal evolution of coseismic deposits due to rainfall is quantified at the valley scale to further obtain the sediment transport capacity. The results show that the relative average thickness predominantly controls the evolution pattern of the coseismic deposits. The sediment transport capacity, which is primarily influenced by rainfall conditions and topography, can be drastically increased by dam breaching and channel narrowing. Moreover, the computed export time, which significantly varies with the spatiotemporal distribution of deposits and the local climate, ranges from 2 to 80 years in the areas affected by the Wenchuan earthquake. This study contributes to providing scientific guidelines for efficiently managing postseismic geohazards and planning for disaster mitigation.
相似文献5.
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为研究震后强降雨条件下沟道泥石流产生的力学机制及水力学机理,以都江堰市龙池镇银洞子泥石流沟为研究对象,构建坡面松散堆积体地下水位变化水力模型,按照水力学渗流理论,分析了震后泥石流形成区坡面松散堆积体内潜水位变化的特征和规律,定量研究了动静水压力对坡体的作用特点。根据理论分析、实例验证与物理模拟试验的研究结果,获得了对坡面松散物源启动力学机理、启动临界条件及启动模式的深刻认识: ①在强降雨激发作用下,随着坡体内潜水位不断升高,水力条件不断恶化,最终导致坡面松散堆积体发生失稳破坏; ②堆积体内潜水位高度是坡面面积(S I T D S I H ( P ) ( G d )
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Numerical investigation of rainfall-induced fines migration and its influences on slope stability 总被引：1，自引：1，他引：0
Xiaoqin Lei Zongji Yang Siming He Enlong Liu Henry Wong Xinpo Li 《Acta Geotechnica》2017,12(6):1431-1446
Rainfall-infiltration-induced fines migration within soil slopes may alter the local porosity and hydraulic properties of soils, and is known to be a possible cause of the failure of slopes. To investigate the intrinsic mechanisms, a mathematical formulation capable of capturing the main features of the coupled unsaturated seepage and fines migration process has been presented. Within the formulation, an unsaturated erodible soil is treated as a three-phase multi-species porous medium based on mixture theory; mass conservation equations with mass exchange terms together with the rate equations controlling fines erosion and deposition processes are formulated as the governing equations and are solved by the FEM method. The influences of both the fines detachment and deposition on the stability of slopes under rainfall infiltration have been investigated numerically. The results show that depending on whether the fines move out or get captured at pore constrictions, both desired and undesired consequences may arise out of the fines migration phenomenon. It is suggested that more attention should be paid to those slopes susceptible to internal erosion whose safety analysis cannot be predicted by traditional methods. 相似文献
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降雨滑坡预警的概率分析方法 总被引：3，自引：1，他引：2
滑坡启动的降雨临界值是滑坡预警的关键,由于研究区资料数据有限,关键值难以确定,降雨滑坡预警效果受影响。所以应该对预警结果进行概率分析。本文利用作者在已开发的降雨滑坡预警系统,提出采用降雨滑坡预警概率分析方法进行预警。通过对滑坡与雨量相关性、降雨滑坡启动值等对滑坡预警的时间概率、空间概率及预警概率进行分析,计算危险区内已发生滑坡频率和降雨滑坡发生频率,得到降雨滑坡预警概率使得预警系统更加可靠。并以沐川县为例对模型进行了算例检验,为更科学的对降雨滑坡进行预警提供方法借鉴。 相似文献
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求算界限温度日期的一种新方法──样条函数插值法 总被引：2，自引：0，他引：2
本文根据某站点各月平均气温,通过计算机,用样条函数插值法模拟年温变化曲线,进而直接求算出主要界限温度初终日期、间隔日数及其相应积温,并与用滑动平均法得出的结果进行了比较检验。 相似文献
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Activity and distribution of geohazards induced by the Lushan earthquake,April 20, 2013 总被引：3，自引：0，他引：3
Peng Cui Jianqiang Zhang Zongji Yang Xiaoqing Chen Yong You Yong Li 《Natural Hazards》2014,73(2):711-726
An Ms7.0 earthquake, focal depth 13 km, struck Lushan on April 20, 2013, caused 196 deaths and 21 missing, 13,484 injuries, and affected more than two million people. A field investigation was taken immediately after the quake, and the induced hazards were analyzed in comparison with the Wenchuan earthquake. We have identified 1,460 landslides and avalanches and four dammed lakes, which were generally small and concentrated on high elevation. Avalanches and rockfalls developed in cliffs and steep slopes of hard rocks, including Jinjixia of Baosheng Town and Dayanxia of Shuangshi Town, Lushan, and the K317 section the Xiaoguanzi section north to Lingguan Town along the provincial highway S210. Landslides were relatively less, mainly in moderate and small scales, developing in sandstone, shale, and loose colluviums. Only one single large landslide was observed to turn into debris slide-flow. Dammed lakes were formed by avalanches and landslides, all in small size and of low danger degree. The earthquake-induced hazards distributed in belt on the hanging wall along the faults, and their major controlling factors include tectonics, lithology, structure surface, and landform. More than 99 % landslides were within 30 km to the epicenter, and 678 within 10 km, accounting for 46 % of the total; about 50 % landslides were distributed on slopes between 35° and 55°, and 11 % on slope exceeding 75°; 60 % on slopes at the altitudes between 1,000 and 1,500 m, 77 % on slopes between 900 and 1,500 m; and 24 and 62 % in hard rocks and section between hard and soft rocks, respectively. Compared with the case of Wenchuan earthquake, both the number and extension of landslides and avalanches in Lushan earthquake-affected area are much smaller, only 5.53 % in number and 0.57 % in area. The earthquake has increased the instability of slope and potentiality of landslide and debris flow. Accordingly, the active period is expected to be relatively short comparing with that in Wenchuan earthquake-hit area. However, the insidious and concealed hazards bring difficulty for risk investigation. 相似文献
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