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1.
Stability investigation of hill cut soil slopes along National highway 222 at Malshej Ghat,Maharashtra 总被引：2，自引：0，他引：2
L. K. Sharma Ravi Kumar Umrao Rajesh Singh M. Ahmad T. N. Singh 《Journal of the Geological Society of India》2017,89(2):165-174
The section of about 12 km of National highway 222 passing through the Malshej Ghat experience frequent slope failure due to complex geological condition, heavy rainfall and slope geometry. The area is part of Western Ghat Deccan trap and slope masses are made of basalt and its weathered crust (debris/soil). The soil slope failure problem mainly occur in rainy seasons due to induced pore water pressure and reduced strength of the slope mass. The present study has been carried out to investigate the slope forming material and assess the stability of soil slopes by numerical approach. For the identification of the vulnerable zones, field study has been carried out and five vulnerable soil slopes identified namely MGS1, MGS2, MGS3, MGS4 and MGS5 on the basis of degree of weathering and slope geometry. The laboratory experiments were carried out to determine the strength properties of the geomaterials. All the input variables acquired from the field and laboratory experiments have been used for numerical simulation, which was performed with the help of limit equilibrium method (LEM) and finite element method (FEM). Numerical analysis provides understanding of the slope behaviour and illustrates that MGS1 and MGS3 are stable slopes, MGS2 and MGS4 are critically stable, whereas, slope MGS5 is unstable. This study recommend the protection of soil slopes and suggest that more detailed investigation is required for long term remedial measures to prevent risk of damage in Malshej Ghat. 相似文献
2.
Identification of deformation and failure characteristics in cataclinal slopes using physical modeling 总被引：1，自引：1，他引：0
This study investigates the deformation characteristics of cataclinal slopes in central Taiwan prior to landslide failure. Field surveys and physical model tests were performed to explain the gravitational deformation characteristics of cataclinal slopes under various conditions and to derive the deformation process and failure characteristics. The results show that the distribution of erosion gullies (different length of the slope mass), the extent of erosion (different thickness of the slope mass), the foliation dip angle, and the geological material critically affect the deformation of cataclinal slope masses in the study area. The results of physical model tests indicate that increasing the foliation dip angle, the thickness and the length of sliding mass, particle size (spacing between foliations) increases the depth of slope deformation. Foliation dip angle is the most critical factor that controls the deformation of slate slopes. When the cataclinal slopes reached maximum deformation, a shear failure and translational slide occurred within a short period. The deformation zone exhibited significant cracking at the scarp and the bulging of the slope toe, which facilitated the infiltration of surface water and groundwater, accelerating the deformation to failure. 相似文献
3.
The 2010–2011 Canterbury earthquake sequence in New Zealand exposed loess-mantled slopes in the area to very high levels of seismic excitation (locally measured as >2?g). Few loess slopes showed permanent local downslope deformation, and most of these showed only limited accumulated displacement. A series of innovative dynamic back-pressured shear box tests were undertaken on intact and remoulded loess samples collected from one of the recently active slopes replicating field conditions under different simplified horizontal seismic excitations. During each test, the strength reduction and excess pore water pressures generated were measured as the sample failed. Test results suggest that although dynamic liquefaction could have occurred, a key factor was likely to have been that the loess was largely unsaturated at the times of the large earthquake events. The failure of intact loess samples in the tests was complex and variable due to the highly variable geotechnical characteristics of the material. Some loess samples failed rapidly as a result of dynamic liquefaction as seismic excitation generated an increase in pore water pressure, triggering rapid loss of strength and, thus, of shear resistance. Following initial failure, pore pressure dissipated with continued seismic excitation and the sample consolidated, resulting in partial shear strength recovery. Once excess pore water pressures had dissipated, deformation continued in a critical effective stress state with no further change in volume. Remoulded and weaker samples, however, did not liquefy and instead immediately reduced in volume with an accompanying slower and more sustained increase in pore pressure as the sample consolidated. Thereafter, excess pressures dissipated and deformation continued at a critical state. The complex behaviour explained why, despite exceptionally strong ground shaking, there was only limited displacement and lack of run-out: dynamic liquefaction was unlikely to occur in the freely draining slopes. Dynamic liquefaction, however, remained a plausible mechanism to explain loess failure in some of the low-angle toe slopes, where a permanent water table was present in the loess. 相似文献
4.
基于非线性Mohr-Coulomb破坏准则,结合极限分析上限法和拟静力分析法,建立功能方程,推导了地震效应下裂缝边坡的安全系数计算方程。采用数学规划方法,计算了不同参数组合条件下的边坡安全系数值,详细分析了非线性条件下一系列参数对边坡稳定性的影响。研究表明,边坡安全系数随非线性参数和地震效应的增大而减小。对比分析可知,在非线性破坏准则下,裂缝深度较大时,裂缝对边坡稳定性影响显著,且边坡越陡影响越大;当裂缝深度超过某个值后,临界破坏面起始端可能不穿过裂缝最底端,而是从裂缝中间某部位穿过。在地震效应作用下,非线性抗剪强度参数对安全系数影响显著。研究成果进一步完善了裂缝边坡稳定性分析内容,所列图表为边坡的设计与施工提供有益参考。 相似文献
5.
考虑坡顶均布荷载和地震效应典型情况下,将边坡滑体进行任意斜条块划分,建立了具有倾斜界面的多块体破坏模型。基于极限分析上限法和非线性摩尔-库仑破坏准则,考虑岩体内正应力的不均匀性,引入多点切线法和强度折减法推导得出边坡临界破坏状态下的安全系数Fs通用计算公式。采用序列二次规划法对安全系数Fs的目标函数进行最优化计算,并与既有研究成果进行对比分析,其结果具有较好的一致性,相对误差不超过3.565%,表明了该方法的正确性。同时对比传统单点切线法计算结果,多点切线法较单点切线法获得的边坡安全系数值偏小,表明了多点切线斜条分法偏于保守,是安全的。参数分析表明坡顶均布荷载、地震效应和非线性参数均对边坡安全系数及潜在临界滑裂面有重要影响。多点切线法引入非线性摩尔-库仑破坏准则对边坡进行稳定性极限分析,为相关研究人员提供了一种新的思路与方法。 相似文献
6.
Zuoan Wei Guangzhi Yin J. G. Wang Ling Wan Liping Jin 《Environmental Earth Sciences》2012,67(6):1651-1662
The stability of both natural and cut slopes in mountainous areas is a great challenge to highway constructions and operations. This paper presents a successful case study of stability analyses and protection treatments for high-steep cut soil slopes in an ancient landslide zone which was located at Km12+700 to Km15+000 along the Tehran?CChalus highway. This report has three parts. First, geotechnical investigations of in situ direct shear test, SPT tests and laboratory tests were implemented to get the subsurface profiles and the mechanical properties of the soil mass. Second, finite difference analysis was carried out to evaluate the stability of both the natural and cut slopes. Minimum safety factors and potential failure modes of cut slopes were obtained under both static and dynamic conditions. These results indicated that the ancient landslide could not be reactivated under the present climatic and morphological conditions, but there were some potential shallow failures in some cut soil slopes (failure actually occurred during excavation). Protection treatments and reinforcements were thus necessary. Third, the stability of the cut slopes was re-assessed by simplified Bishop limit equilibrium analysis (using Slide 5.0). Some potential failure zones were designed to be protected by back-anchored concrete retaining wall at the slope toe, rock bolts and frame beams on the slope face and planting grass on the slope face. Numerical analysis indicated that these protection measures could stabilize this remedial slope. These practical experiences may be of benefit for similar highway construction projects. 相似文献
7.
基于极限分析上限定理,考虑均匀加筋和三角形加筋两种加筋模式,采用拟静力分析方法推导了一定边坡高度条件下的三维加筋边坡临界加筋强度的计算公式。通过与已有文献结果的对比,验证了所提方法的正确性,并讨论了边坡宽高比、水平和竖向地震力系数对三维边坡稳定性的影响。结果表明:地震力作用下边坡临界加筋强度随边坡宽高比的增大而增加,但其变化速率逐渐减小,当边坡宽高比大于10时,三维边坡加筋强度与二维情况相近;随着水平地震作用的增大,三维边坡临界加筋强度呈非线性增大;随着竖向地震作用的增大,临界加筋强度大致呈线性增加,且随着坡角的增大,竖向地震作用对临界加筋强度的影响更加显著;两种加筋模式下的边坡临界加筋强度值变化规律一致,且三角形加筋模式所需的加筋强度较小,效果较优。最后,针对实际工程提出了一些工程建议。 相似文献
8.
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。 相似文献
9.
S. Sreekumar 《Journal of the Geological Society of India》2009,73(6):813-820
The occurrences of slope failures are frequent in Idukki district of Kerala state particularly along the road cuttings and
hill slopes causing disruption in traffic, loss of lives and property. This demands a critical evaluation of stability of
slopes along the hill roads. This paper deals with stability analysis of a typical hard rock profile at Chuzhappu and a lateritic
profile at Kumili along the road connecting Kottayam and Kumili. A large number of factors have been examined and studied;
the orientation of discontinuities has been identified as one of the major inherent factors influencing slope instability
along Chuzhappu hard rock profile. These have been analysed carefully using stereographic/equal area projection technique
in order to determine the vulnerability to slope failure and to understand the type of rock slide that can occur in this profile.
The buoyant force of water acting along the discontinuities after heavy rain storm further aids the down slope movement. As
the laterite slope is mostly homogeneous, Bishops method and Swedish method were adopted for stability analysis of laterite
slope at Kumili. The study also examines the efficacy and applicability of the different methods employed in soil mechanics
to assess the stability of laterite slope.The results obtained by this method are compared by actual field conditions. The
stability assessment indicates that two sectors at Chuzhappu and one sector at Kumili profile are at the geo-technical threshold
of failure, when piezometric head rises during rainstorm. The study indicates that these methods are highly useful in determining
the Factor of Safety in profiles with similar geological setting. 相似文献
10.
A set of analytical solutions achieved by the upper bound theorem of limit analysis and the pseudo‐static approach is presented for the assessment of the stability of homogeneous c, ϕ slopes manifesting vertical cracks and subject to seismic action. Rotational failure mechanisms are considered for slopes with cracks of either known or unknown depth and location. A validation exercise was carried out based on numerical limit analyses and displacement‐based finite‐element analyses with strength reduction technique. Charts providing the stability factor for fissured slopes subject to both horizontal and vertical accelerations for any combination of c, ϕ and slope inclination are provided. The effect of the direction of the vertical acceleration on slope stability is specifically analysed. Yield seismic coefficients are also provided. When the presence of cracks within the slope can be ascertained with reasonable confidence, maps showing the zones within the slope where they have no destabilising effect are provided. Finally, Newmark's method was employed to assess the effect of cracks on earthquake induced displacements. To this end, displacement coefficients are provided in chart form as a function of the slope characteristics. Two examples of slopes subjected to known earthquakes are illustrated. © 2016 The Authors. International Journal for Numerical and Analytical Methods in Geomechanics published by John Wiley & Sons Ltd. 相似文献
11.
A. Malarvizhi Achyuthan Hema D. Gobichandhru 《Journal of the Geological Society of India》2016,87(3):317-322
Occurrences of landslide are most common and critical issue in North-East India. The various types of slope failures have been affected most part of slopes and road section between Malidor to Sonapur area (approx 30 Km) along NH-44 within Jaintia hills district, Meghalaya, India. These slope failures causes considerable loss of life and property along with many inconveniences such as disruption of traffic along highways. The unscientific excavations of rock slopes for road widening or construction purposes may weaken the stability of the slopes. The rocks exposed in the area are highly jointed sandstone and shale of Barail Group of Oligocene age. The Sonapur landslide is most dangerous and destructive rock fall-cum debris flow. The present study includes the kinematic analysis of the slope to assess the potential failure directions as the rocks are highly jointed in some parts of road cut sections. The continuous slope mass rating (CSMR) technique has been applied for slope stability analysis at five vulnerable locations. Kinematic analysis indicates mainly wedge type of failure along with few toppling and planar failures. These failure required immediate treatment to prevent the slide and long term stability of the slope. 相似文献
12.
映秀—卧龙公路沿线汶川地震地质灾害研究 总被引：4，自引：0，他引：4
映秀—卧龙公路是汶川地震灾区距震中最近、震害最为严重的一条公路,本文对沿线地震地质灾害进行了详细的调查研究。依据震害特征,将沿线震害划分为斜坡中上部强风化岩体及土层失稳、结构面切割岩体崩滑失稳、滑坡、泥石流等4类,并分析了沿线震害发育规律。调查表明:龙门山后山断裂两侧地震地质灾害呈现显著的差异性,主要是由深大断裂的消震隔震效应,地貌放大效应,地质结构等三方面因素决定的。通过134条实测剖面分析,研究了地震失稳斜坡坡度和失稳部位。地震诱发失稳斜坡坡度在33°~84°之间,主要分布在41°~65°之间,可以认为地震诱发斜坡失稳灾害主要发生在40°以上的斜坡。斜坡失稳部位主要分布在斜坡中上部以及地貌突出部位,主要失稳部位在0.4坡高以上。从研究斜坡动力失稳的角度,将沿线斜坡划分为基岩-土层及强风化层斜坡地质结构、不利外倾结构面基岩斜坡地质结构、块状构造基岩斜坡地质结构、块碎石土层斜坡地质结构等几种地质结构模型,分析论述了各种地质结构相应的地震地质灾害类型及特点。 相似文献
13.
Light rain or moderate rain is the most common meteorological event in the rainy season in the loess area of China, so the probability of landslide hazards induced by the coupling effect of earthquakes and rainfall under the condition of light rain or moderate rain is relatively higher than that under heavy rain. To study the dynamic response characteristics and instability mechanism of loess slopes by the coupling effect of earthquakes and rainfall under the conditions of moderate rain and light rain, a low-angle slope model test of a large-scale shaking table after 10 mm of rainfall was carried out. By gradually increasing the dynamic loading, the evolution of the macroscopic deformation and the instability failure mode of the slope model are observed; the temporal and spatial trends of the amplification effect, acceleration spectrum, pore pressure and soil pressure are analyzed; and the failure mechanism of the slope is determined. The results showed that the amplification effect increased along the slope surface upward, and a strong amplification effect appeared at the front of the top of the slope. Because of the stronger dynamic stress action on the upper part of the slope, the immersed soil in the upper part of the slope experienced seismic subsidence deformation, the saturation in the seismic subsidence soil increased, and the water content temporarily increased locally. With the further increase in the loading intensity, a large number of tension cracks were generated in the seismic subsidence area, and water infiltrated down along the cracks and the wetting range expanded under dynamic action. The range of seismic subsidence and cracks further extended to the deep part of the slope. Under the reciprocating action of the subsequent ground motion, the swing amplitude of the soil mass in the seismic subsidence area, which is divided by a large number of cracks in the upper part of the slope, increased further, resulting in the further reduction in the residual strength of the seismic subsidence soil mass located at the crack tip due to the pull and shear action. Finally, under the combined action of gravity and dynamic force, the upper soil mass in the seismic subsidence area dragged the lower soil mass in the seismic subsidence area downward because the sliding force is greater than the residual strength of the soil mass, which induced a seismic subsidence-type loess landslide. Under the coupling effect of earthquakes and rainfall, the instability mode and mechanism of this landslide are significantly different from those of liquefaction-type landslides.
相似文献14.
R. Trizzino 《Engineering Geology》1987,23(3-4):263-276
A simple method for evaluating the seismic stability of embankments and slopes has been developed by modifying the generalized procedure of slices proposed by Janbu. A pseudostatic analysis is carried out. The seismic force is represented through its horizontal and vertical components, acting on the centre of gravity of the soil mass. Defining a nominal state of plastic equilibrium, the safety factor of the slope for a given value of the seismic force is obtained through an iterative procedure that converges very rapidly. Moreover, by assuming a seismic force of intensity varying from zero value (static condition) up to a limit value, depending on the seismicity of the area, one can obtain the “influence lines” of the horizontal and vertical acceleration. Finally, a directional parametric analysis has been carried out considering a seismic force of a given intensity, acting in a direction varying from 0° to 360° with respect to the vertical axis through the gravity centre of the slope. By means of this procedure it is possible to locate a “critical zone” for the slope, i.e., that one within which any seismic force can cause the failure of the slope. Moreover, it appears that it is incorrect to consider only the horizontal acceleration in the stability analyses of slopes under earthquake loading conditions, as the most dangerous direction is usually different from the horizontal one. 相似文献
15.
地震效应和坡顶超载对均质土坡稳定性影响的拟静力分析 总被引：3，自引：0，他引：3
基于强度折减技术和极限分析上限定理,假定机动容许的速度场破坏面,考虑坡顶超载、水平和竖向地震效应影响推导了边坡稳定性安全系数的计算表达式。采用序列二次规划迭代方法（和内点迭代方法）对边坡安全系数目标函数进行能量耗散最小化意义上的优化计算,与多个算例的对比验证了其方法和程序计算的正确性;对影响土质边坡动态稳定性的一些因素进行了参数分析,分析表明：随着边坡倾角?、坡顶超载q、水平和竖向地震效应影响系数的增大,边坡稳定性安全系数显著下降;随着坡顶超载q、水平地震效应影响系数kh的增大、竖向地震效应影响系数kv的减小,边坡的潜在滑动面越来越深,潜在破坏范围越来越大。竖向地震效应对边坡稳定性也有一定影响,强震条件下的设计计算必须考虑竖向地震效应的影响。 相似文献
16.
17.
This paper presents probabilistic assessment of seismically-induced slope displacements considering uncertainties of seismic ground motions and soil properties.A stochastic ground motion model representing both the temporal and spectral non-stationarity of earthquake shakings and a three-dimensional rotational failure mechanism are integrated to assess Newmark-type slope displacements.A new probabilistic approach that incorporates machine learning in metamodeling technique is proposed,by combining relevance vector machine with polynomial chaos expansions(RVM-PCE).Compared with other PCE methods,the proposed RVM-PCE is shown to be more effective in estimating failure probabilities.The sensitivity and relative influence of each random input parameter to the slope displacements are discussed.Finally,the fragility curves for slope displacements are established for sitespecific soil conditions and earthquake hazard levels.The results indicate that the slope displacement is more sensitive to the intensities and strong shaking durations of seismic ground motions than the frequency contents,and a critical Arias intensity that leads to the maximum annual failure probabilities can be identified by the proposed approach. 相似文献
18.
针对现有考虑应变软化效应的边坡渐进破坏分析模型中计算假定条件不符合实际情况的不足,以三峡库区赵树岭滑坡为研究对象,考虑地下水位波动和地震力的影响,提出用于分析多场耦合条件下应变软化边坡渐进破坏模式及稳定性可靠度的方法.结果表明,地下水位波动和地震力会不同程度地影响滑坡的渐进破坏模式和破坏概率.滑坡在145 m、175 m水位和库水位从175 m陡降为145 m三种工况下整体稳定,但分别有14.119%、20.266%和21.797%的概率发生局部渐进破坏;在烈度为Ⅶ的地震力作用下同时考虑3种蓄水工况,该滑坡分别有34.067%、38.061%和38.405%的概率发生整体渐进破坏;根据滑坡渐进破坏模式指出最佳加固位置应在沿江大道前沿.该分析方法具备可靠性,可为边坡的渐进破坏模式及稳定性评价研究提供参考. 相似文献
19.
Satish Kumar Kishor Kumar N. N. Dogra 《Journal of the Geological Society of India》2017,89(4):407-412
Rock slopes require geo-engineering evaluation to assess the instability of critical slopes leading to landslides particularly in Himalayan terrain where rocks are highly jointed, fractured and weathering prone. Interplay of discontinuities in the rocks coupled with other parameters is one of the prime causes of failure of slopes. Engineering rock mass classification, such as, rock mass rating (RMR) and slope mass rating (SMR) along with geological strength index (GSI) have widely been used for stability assessment of rock slopes above tunnel portals, and these classifications are employed here for assessment of stability of slopes of critical nature along Rampur-Powari highway in Himachal Pradesh. In the present study, out of 154 numbers of slopes, a total of 29 have been selected for assessment of their criticality by employing RMR, SMR and GSI. 相似文献
20.
Finite Element (FE) pseudo-static analysis can provide a good compromise between simplified methods of dynamic analysis and time domain analysis. The pseudo-static FE approach can accurately model the in situ, stresses prior to seismic loading (when it follows a static analysis simulating the construction sequence) is relatively simple and not as computationally expensive as the time domain approach. However this method should be used with caution as the results can be sensitive to the choice of the mesh dimensions. In this paper two simple examples of pseudo-static finite element analysis are examined parametrically, a homogeneous slope and a cantilever retaining wall, exploring the sensitivity of the pseudo-static analysis results on the adopted mesh size. The mesh dependence was found to be more pronounced for problems with high critical seismic coefficients values (e.g. gentle slopes or small walls), as in these cases a generalised layer failure mechanism is developed simultaneously with the slope or wall mechanism. In general the mesh width was found not to affect notably the predicted value of critical seismic coefficient but to have a major impact on the predicted movements. 相似文献