landslide stability
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2021 ◽  
Author(s):  
Zhiqiang Fan ◽  
Yanhao Zheng

Abstract In the Three Gorges Reservoir (TGR) area, the accumulation landslide characterized by stepped slip surfaces is widely developed, and its stability is significantly affected by the fluctuation of reservoir water level. In this paper, the Shuping landslide, a typical accumulation landslide in the TGR area, was selected to study the effect of water level fluctuations on landslide stability. Based on Multi-Circular (M-C) model, it is found that the decline of reservoir water level was the dominant factor causing the decrease of landslide stability. At the end of the decline of reservoir water level, the landslide stability was minimum and the corresponding moment was the most dangerous. The effect of the drawdown speed of reservoir water level on the minimum value of landslide stability had a threshold effect, although the minimum stability coefficient of landslide decreased with the increase of drawdown speed. Under the most dangerous water level conditions, the stability of the piled landslide increased linearly with the increase of the net thrust of piles. Also, by comparing with other classical models, the effectiveness of the M-C model in evaluating landslide stability under the dynamic changes of reservoir water level was verified. The results could provide a reliable scientific basis for improving the stability analysis and reinforcement measures of the accumulation landslide with the multi-circular slip surfaces in the TGR area, as well as can be applied to similar landslides in reservoir areas.


2021 ◽  
Author(s):  
Fuyu Yan ◽  
Lianrong Wu ◽  
Xining Sun ◽  
Qiwu Shen ◽  
Qiaofeng Dong ◽  
...  

Abstract The normal operation of Yulangpei tailings reservoir is affected by landslide stability. In this paper, taking the main and side slopes near the dam bank of the Yulangpei ditch as an example, water-soil coupling theory is applied to comprehensively evaluate the reliability of the side slopes of the tailings reservoir. Grading and seepage prevention (GSP) measures and the suction of the substrate are considered, as well as the infiltration of different rainfall and reservoir water levels. We numerically simulate the typical three forms of side slopes under the coupling conditions and conduct a reliable and comprehensive evaluation of tailings reservoir side slopes. The study shows that under six reservoir water level changes, the factor of safety (FS) of the bank slope shows a hysteresis effect. According to nine rainfall infiltration conditions and during rainfall, the greater the rainfall intensity, the greater the weakening effect. When rainfall stops, the FS rebounds. After GSP measures, the initial stability of the bank slope under different conditions is improved, but the main slope is more sensitive to changes in rainfall and water levels.


Water ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 3479
Author(s):  
Chun-Hung Wu

The sediment yield from numerous landslides triggered in Taiwan’s mountainous regions by 2009 Typhoon Morakot have had substantial long-term impacts on the evolution of rivers. This study evaluated the long-term evolution of landslides induced by 2001 Typhoon Nari and 2009 Typhoon Morakot in the Tsengwen Reservoir Watershed by using multiannual landslide inventories and rainfall records for the 2001–2017 period. The landslide activity, vegetation recovery time, and the landslide spatiotemporal hotspot analyses were used in the study. Severe landslides most commonly occurred on 35–45° slopes at elevations of 1400–2000 m located within 500 m of the rivers. The average vegetation recovery time was 2.29 years, and landslides with vegetation recovery times exceeding 10 years were most frequently retrogressive landslide, riverbank landslides in sinuous reaches, and the core area of large landslides. The annual landslide area decline ratios after 2009 Typhoon Morakot in Southern Taiwan was 4.75% to 7.45%, and the time of landslide recovery in the Tsengwen reservoir watershed was predicted to be 28.48 years. Oscillating hotspots and coldspots occupied 95.8% of spatiotemporal patterns in the watershed area. The results indicate that landslides moved from hillslopes to rivers in the 2001–2017 period because the enormous amount of sediment deposited in rivers resulted in the change of river geomorphology and the riverbank landslides.


2021 ◽  
Author(s):  
Weinan Fan ◽  
Junxiang Liu ◽  
Wenxiong Mo ◽  
Le Luan ◽  
Yong Wang ◽  
...  

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Zhaodan Cao ◽  
Jun Tang ◽  
Xiaoer Zhao ◽  
Yonggang Zhang ◽  
Bin Wang ◽  
...  

The stability of the reservoir bank landslide is affected by a variety of external factors, and the fluctuation of reservoir water level is one of the important influencing factors. The Erdaohe landslide is a typically colluvial landslide in the Three Gorges Reservoir area with periodic reservoir water level fluctuations. According to landslide displacement data, the displacement of the Erdaohe landslide exhibits the significantly stepwise feature. Its failure mechanism was analyzed using strength reduction method by the FLAC3D package in the case of reservoir water level changes. The results indicate that the hydrodynamic pressure has an important impact on the initialization of the landslide failure. When reservoir water level rises rapidly or maintains constant at the lower level, the landslide stability would be higher. When the reservoir water level decreases rapidly or maintains constant at the higher level, the landslide stability will be smaller. When the reservoir water level was in the lowest elevation, the factor of safety (FS) reached the minimum value of 1.11. Findings in this paper can provide guidelines for the risk assessment of colluvial landslides.


2021 ◽  
pp. 795-801
Author(s):  
Lei Shi ◽  
Zhongzheng Liu ◽  
Liangyan Yang

Loess landslide is a common geological disaster in northern Shaanxi, which seriously affects people's life and property safety and social and economic development. The research on vegetation restoration types and hydrological and mechanical properties of loess landslides can provide basic data support for landslide stability prediction, and further provide reference for landslide prevention and treatment. In the present study, the loess landslide point of Zhang Zi Gou in Gan Quan County, Yan’an City was taken as the research object. On the basis of the existing natural condition data, the basic physical and mechanical properties and hydrological characteristics were obtained by collecting field landslide soil samples for indoor experimental analysis. The indoor analysis shows that the landslide is mainly distributed in dry land, medium coverage and low coverage grassland, indicating that the surface vegetation coverage can affect the stability of landslide. The worse the vegetation coverage, the more landslides occur. The void ratio and porosity of landslide soil decrease with the increase of dry density. The cohesion of natural soil is obviously higher than that of saturated soil, and the internal friction angle of natural soil is slightly lower than that of saturated soil. In general, due to the influence of water content, the shear strength of natural soil samples is higher than that of saturated soil samples. Therefore, in order to improve the accuracy of prediction and early warning system, it is necessary to consider the response of hydrological and mechanical properties of loess to vegetation restoration. The results provide basic data support for the establishment of loess landslide stability prediction system and provide reference for geological disaster management. Bangladesh J. Bot. 50(3): 795-801, 2021 (September) Special


Landslides ◽  
2021 ◽  
Author(s):  
Zaizhi Yang ◽  
Xingwu Duan ◽  
Jiangcheng Huang ◽  
Yifan Dong ◽  
Xinbao Zhang ◽  
...  

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Pai Lifang ◽  
Wu Honggang ◽  
Yang Tao ◽  
Zhong Feifei

In this paper, a pseudostatic seismic coefficient evaluation method for slope dynamic stability analysis was explored with Yushu Airport Road 3# landslide as a typical engineering case, and the shaking table test and numerical calculation were performed during the exploration. The loading waveform was selected as Yushu wave, and the acceleration time-history of seismic waves was measured and analyzed, revealing the failure mode of slopes. Based on the rigid-body limit equilibrium theory, the instantaneous additional seismic forces of each block and the time-history landslide stability coefficient were calculated. According to the time-history of the landslide, dynamic stability coefficients were calculated. Subsequently, we proposed a pseudostatic seismic coefficient evaluation method and discussed the seismic coefficient slope dynamic stability analysis. The results showed that as the vibration frequency rose, the average acceleration and the residual displacement of the slope decreased, but the slope grew more dynamically stable. With the proposed method, we calculated the period of slope seismic action to be 0.126 s and the average maximum acceleration to be 0.156 g, which was close to the designed ground motion acceleration of 0.15 g. Besides, we calculated the safety factor of landslides under earthquake to be 0.93∼0.97, which was close to that obtained from the building code method and in accordance with the present seismic deformation and failure mode of landslides. Moreover, the results obtained from the method of nuclear power plant specification were relatively small compared to other specification methods. The research is significant because it provides a new idea for the evaluation of seismic landslide stability in practical engineering.


Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 5243
Author(s):  
Cheng Zhong ◽  
Chang Li ◽  
Peng Gao ◽  
Hui Li

Post-seismic vegetation recovery is critical to local ecosystem recovery and slope stability, especially in the Wenchuan earthquake area where tens of thousands of landslides were triggered. This study executed a decadal monitoring of post-seismic landslide activities all over the region by investigating landslide vegetation recovery rate (VRR) with Landsat images and a (nearly) complete landslide inventory. Thirty thousand landslides that were larger than nine pixels were chosen for VRR analysis, to reduce the influence of mixed pixels and support detailed investigation within landslides. The study indicates that about 60% of landslide vegetation gets close to the pre-earthquake level in ten years and is expected to recover to the pre-earthquake level within 20 years. The vegetation recovery is significantly influenced by topographic factors, especially elevation and slope, while it is barely related to the distance to epicenter, fault ruptures, and rivers. This study checked and improved the knowledge of vegetation recovery and landslide stability in the area, based on a detailed investigation.


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