Stability Analysis of Accumulation Landslides in the Three Gorges Reservoir Area Under Reservoir Water Level Fluctuation Based on Multi-Circular Model

2021 ◽  
Author(s):  
Zhiqiang Fan ◽  
Yanhao Zheng
Keyword(s):  
Stability Analysis ◽  
Water Level ◽  
Three Gorges Reservoir ◽  
Three Gorges ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Landslide Stability ◽  
Slip Surfaces ◽  
The Three Gorges ◽  
The Stability

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.

scholarly journals Failure Mechanism of Colluvial Landslide Influenced by the Water Level Change in the Three Gorges Reservoir Area

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Zhaodan Cao ◽  
Jun Tang ◽  
Xiaoer Zhao ◽  
Yonggang Zhang ◽  
Bin Wang ◽  
...  
Keyword(s):  
Water Level ◽  
Failure Mechanism ◽  
Three Gorges Reservoir ◽  
Three Gorges Reservoir Area ◽  
Three Gorges ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Landslide Stability ◽  
The Three Gorges ◽  
Colluvial Landslide

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.

scholarly journals The Coupling Effect of Rainfall and Reservoir Water Level Decline on the Baijiabao Landslide in the Three Gorges Reservoir Area, China

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Nenghao Zhao ◽  
Bin Hu ◽  
Qinglin Yi ◽  
Wenmin Yao ◽  
Chong Ma
Keyword(s):  
Water Level ◽  
Three Gorges Reservoir ◽  
Coupling Effect ◽  
Three Gorges Reservoir Area ◽  
Three Gorges ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Reservoir Area ◽  
The Three Gorges ◽  
Water Level Decline

Rainfall and reservoir level fluctuation are two of the main factors contributing to reservoir landslides. However, in China’s Three Gorges Reservoir Area, when the reservoir water level fluctuates significantly, it comes at a time of abundant rainfall, which makes it difficult to distinguish which factor dominates the deformation of the landslide. This study focuses on how rainfall and reservoir water level decline affect the seepage and displacement field of Baijiabao landslide spatially and temporally during drawdown of reservoir water level in the Three Gorges Reservoir Area, thus exploring its movement mechanism. The monitoring data of the landslide in the past 10 years were analyzed, and the correlation between rainfall, reservoir water level decline, and landslide displacement was clarified. By the numerical simulation method, the deformation evolution mechanism of this landslide during drawdown of reservoir water level was revealed, respectively, under three conditions, namely, rainfall, reservoir water level decline, and coupling of the above two conditions. The results showed that the deformation of the Baijiabao landslide was the coupling effect of rainfall and reservoir water level decline, while the latter effect is more pronounced.

scholarly journals The study on the time lag of water level in the Three Gorges Reservoir under the regulation processes

2021 ◽  
Author(s):  
Kunlong He ◽  
Hongwei Shi ◽  
Chenchen Chen ◽  
Yao Cheng ◽  
Jiao Liu
Keyword(s):  
Water Level ◽  
Three Gorges Reservoir ◽  
Flood Control ◽  
Time Lag ◽  
Three Gorges ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
The Three Gorges Reservoir ◽  
The Three Gorges ◽  
Operation Period

Abstract The identification of the water level time lag (WLTL) under the regulation processes is of great significance for environmental impact, flood control, and sediment transport of huge reservoirs. The traditional hydrodynamic method can calculate the flood inflow process and the water level change process along the river channel, but it is difficult to estimate the time difference of the reservoir water level fluctuation to the dispatching process. To quantitatively evaluate the reservoir regulation effect on the WLTL in the Three Gorges Reservoir (TGR), the daily water level data from 2011 to 2017 of five stations in the TGR are analyzed in this paper. The results revealed that there is a significant water level difference along the reservoir from April 1 to October 31. The gap between the end of the reservoir and the Three Gorges Dam (TGD) is the largest, reaching 23.67 m on July 2. The longer the distance from the TGD, the longer the time lag. Furthermore, the WLTL is also different at the four different operating periods of the reservoir in a year. During the low water level operation period and high water level operation period, the time lag is 3 days which is the greatest, while in the water level decline period and water level rise period, the time lag is within 2 days.

Groundwater Dynamics Analysis of Sanmashan Side Slope in the Three Gorges Reservoir Region, China

2011 ◽  
Vol 250-253 ◽  
pp. 1744-1751
Author(s):  
Jin Guo Wang ◽  
Zhi Fang Zhou
Keyword(s):  
Water Level ◽  
Three Gorges Reservoir ◽  
Hydrodynamic Pressure ◽  
Three Gorges ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
The Three Gorges Reservoir ◽  
Side Slope ◽  
The Three Gorges ◽  
Three Gorges Reservoir Region

Sanmashan side slope in the Three Gorges reservoir region is located in the center area of the Xincheng district, Fengjie county, China. Based on the analysis of hydrogeological structure of the studied area, one can conclude that a groundwater reservoir form near the side slope area after the impoundment of the Three Gorges Reservoir, which induces large groundwater pressure on the side slope. In particular, large hydrodynamic pressure will occur in the landslide mass under the condition of the reservoir water level descending significantly, which has bad effects on slope stability. Numerical simulation results show that the seepage force on landslide is 43 times of that under normal situation, as the reservoir water level declining dramatically from 175m to 145m. Thus, the influence of hydrodynamic pressure should be considered in the stability calculation.

scholarly journals Phreatic line calculation and stability analysis of slopes under the combined effect of reservoir water level fluctuations and rainfall

2017 ◽  
Vol 54 (5) ◽  
pp. 631-645 ◽  
Author(s):  
Guanhua Sun ◽  
Yongtao Yang ◽  
Shengguo Cheng ◽  
Hong Zheng
Keyword(s):  
Water Level ◽  
Three Gorges Reservoir ◽  
Combined Effect ◽  
Water Level Fluctuations ◽  
Three Gorges Reservoir Area ◽  
Three Gorges ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Reservoir Area ◽  
The Three Gorges

Rainfall and reservoir water level fluctuations are the main external factors of landslides in the Three Gorges Reservoir area. To improve the analysis of slope stability under the combined effect of reservoir water level fluctuations and rainfall, a simplified method for phreatic line calculation of slopes is proposed in this study. Based on the obtained phreatic line, the expression of normal stress on the sliding surface of the slope under the hydrodynamic forces is deduced, and a global analysis method to solve the slope safety factor under hydrodynamic force is proposed. Finally, the safety evolution of a slope in the Three Gorges Reservoir area is studied under the combined effect of reservoir water level fluctuations and rainfall.

Stability of Huangtupo I# Landslide under Three Gorges Reservoir Operation

2012 ◽  
Vol 170-173 ◽  
pp. 1116-1123 ◽  
Author(s):  
Xin Li Hu ◽  
Hui Ming Tang ◽  
Chang Dong Li ◽  
Ren Xian Sun
Keyword(s):  
Water Level ◽  
Three Gorges Reservoir ◽  
Normal Operation ◽  
Water Level Fluctuations ◽  
Three Gorges ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Stability Coefficient ◽  
Huangtupo Landslide ◽  
The Stability

Abstract. During the normal operation of Three Gorges Reservoir, the water level of the reservoir will fluctuate periodically, which will soften and decrease the shear strength of rock soil on the bank, meanwhile decrease the landslide stability. Huangtupo landslide is a typical large and complex landslide in the Three Gorges Reservoir Region, which is consist of four sub-landslides. In particular, the stability of its riverside Huangtupo I# landslide has a great stake. Based on the analysis of engineering geological condition of Huangtupo landslide, the 2D finite element model of Huangtupo I# landslide(The Riverside Slumping mass I#) was established, the proper mechanical parameters was selected. By using the GeoStudio software, according to the reservoir running curve, the simulation on coupling effect of seepage field and stress field was conducted in 7 different modes within the period of one year. The results showed that: ①the reservoir water level fluctuations will affect both the displacement in saturated and un-saturated area of landslide; especially when the water level drawing down sharply; ②the stability coefficient of Huangtupo I# changes with the reservoir water level fluctuations; the minimum stability coefficient occurs 48 days after the water level drawing down and the moment when the water level falls by 11.9m, under that moment the Huangtupo I# is unstable.

scholarly journals Study on the Deformation Mechanism of Reservoir Landslides Considering Rheological Properties of the Slip Zone Soil: A Case Study in the Three Gorges Reservoir Region

2020 ◽  
Vol 12 (16) ◽  
pp. 6427
Author(s):  
Chun Li ◽  
Huiming Tang ◽  
Yankun Wang
Keyword(s):  
Water Level ◽  
Three Gorges Reservoir ◽  
Water Level Fluctuation ◽  
Level Fluctuation ◽  
Three Gorges ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
The Three Gorges ◽  
Reservoir Water Level Fluctuation

Reservoir water level fluctuation is one of the main extrinsic factors that could change the stress field in landslides, as well as the mechanical strength of geomaterials, hence affecting the deformation and stability of landslides. The largest reservoir landslide in the Three Gorges Reservoir area was selected for a case study. The impact of reservoir water level fluctuation is represented by the dynamic change in the underground seepage field and was thereby analyzed with numerical modeling. The deformation behavior considering the rheological properties of the slip zone soil was studied. The sudden change in the displacement–time curve was selected as the failure criterion for the investigated landslide. The evolution process of the accelerated deformation stage was divided into slow acceleration, fast acceleration, and rapid acceleration stages. The Huangtupo landslide is characterized by a retrogressive landslide and is currently in the creep deformation stage; the deformation mechanism and deformation characteristics are closely related to the reservoir water level fluctuation. Research was carried out by means of field investigation, in situ monitoring, and numerical simulation to provide a true and reliable result for stability evaluation.

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