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Response of an old landslide to reservoir filling: A case history

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Science China(Technological Sciences) 2005年第Z1期48卷 27-32页

作者： L.G. Tham C.F. Lee Department of Civil Engineering University of Hong Kong Hong Kong China

Unfavorable hydrodynamic evolution is considered as the major cause leading to reservoir slope instability and is often modeled by numerical method. However, this simulation is seldom checked by systematic field instrumentation. Taking the opportunity of filling the Three Gorges Reservoir, a system was established in Xietan landslide to monitor reservoir water level, subground water level, seepage pressure, rainfall and deformation, etc. The monitored data during reservoir filling shows that: (1) The water level rise in the bank lags behind the reservoir filling and the lag time depends on the bank permeability; (2) rainfall-induced subground water rise and its lag time is closely correlated to hourly rainfall, indicating that it is not feasible or sufficient to use daily rainfall for analysis; (3) the effect of inverse seepage during reservoir filling on stability is ephemeral and reservoir filling is the major cause leading to bank instability.

关键词： reservoir filling, old landslide, monitoring system, water level, deformation.

A new method for spatio-temporal prediction of rainfall-induced landslide

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Science China Earth Sciences 2006年第4期49卷 421-430页

作者： DING Jixin1,2, YANG Zhifa2, SHANG Yanjun2, ZHOU Shenghua1 & YIN Juntao3 1. China Non-ferrous Metals Resource Geological Survey, Beijing 100012, China 2. Institute of Geology and Geophysics, Chinese Academy of Sciences, Key Laboratory of Engineering Geomechanics, Beijing 100029, China 3. School of Geoscience & Environmental Engineering, Central South University, Changsha 410083, China China Non-ferrous Metals Resource Geological Survey Beijing China Institute of Geology and Geophysics Chinese Academy of Sciences Key Laboratory of Engineering Geomechanics Beijing China School of Geoscience & Environmental Engineering Central South University Changsha China

Geological condition and rainfall are two most principal conditions inducing landslides in the Chongqing region. By analyzing the forming conditions of rainfall-induced landslides, a new method for spatio-temporal prediction of rainfall-induced landslide is brought forward on the basis of grading and overlapping geological condition and rainfall factor in this paper. At first, semi-quantitative assessment and grading for the geological condition of a certain area or slope can be carried out with the multi-factor interactive matrix. Then the severity of rainfall in that area is grading according to the maximum daily rainfall and the total rainfall in a rainfall course. Finally, the “landslide probability judgement factor” can be worked out through grading and overlapping “geological condition influenc- ing factor” and “rainfall influencing factor”, by which the landslide can be graded into 4 grades, they are landslide extremely easily happening, landslide easily happening, landslide difficultly happening and landslide hardly ever happening respectively. More accurate spatio-temporal prediction of rain- fall-induced landslides can come true on the ground of detailed geological survey of some dangerous slopes in an area and more precise weather forecast. Finally, the reliability and feasibility of carrying out the spatio-temporal prediction of rainfall-induced landslides with the method of “two factors” grading and overlapping are validated by the example of Jipazi landslide.

关键词： rainfall-induced landslide, geological condition, rainfall, two factors, grading and overlapping, interactive matrix, spatio-temporal prediction.

Mechanism analysis of landslide of a layered slope induced by drawdown of water level

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Science China(Technological Sciences) 2005年第Z1期48卷 136-145页

作者： ZHANG Junfeng LI Zhengguo QI Tao Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China

The frequent drawdown of water level of Yangtze River will greatly influence the stability of the widely existing slopes in the Three Gorges reservoir zone, especially those layered ones. Apart from the fluctuating speed of water level, the different geological materials will also play important roles in the failure of slopes. Thus, it must be first to study the mechanism of such a landslide caused by drawdown of water level. A new experimental setup is designed to study the performance of a layered slope under the drawdown of water level. The pattern of landslide of a layered slope induced by drawdown of water level has been explored by means of simulating experiments. The influence of fluctuating speed of water level on the stability of the layered slope is probed, especially the whole process of deformation and development of landslide of the slope versus time. The experimental results show that the slope is stable during the water level rising, and the sliding body occurs in the upper layer of the slope under a certain drawdown speed of water level. In the process of slope failure, some new small sliding body will develop on the main sliding body, and the result is that they speed up the disassembly of the whole slope. Based on the simulating experiment on landslide of a layered slope induced by drawdown of water level, the stress and displacement field of the slope are calculated. The seepage velocity, the pore water pressure, and the gradient of pore water head are also calculated for the whole process of drawdown of water level. The computing results are in good agreement with the experimental results. Accordingly, the mechanism of deformation and landslide of the layered slope induced by drawdown of water level is analyzed. It may provide basis for treating this kind of layered slopes in practical engineering.

关键词： layered slope, landslide, drawdown of water level.

Optimization of causative factors using logistic regression and artificial neural network models for landslide susceptibility assessment in Ujung Loe Watershed, South Sulawesi Indonesia

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Journal of Mountain Science 2019年第2期16卷 383-401页

作者： Andang Suryana SOMA Tetsuya KUBOTA Hideaki MIZUNO Faculty of Forestry Hasanuddin University Faculty of Agriculture Kyushu University

landslide susceptibility maps(LSMs) play a vital role in assisting land use planning and risk mitigation. This study aims to optimize causative factors using logistic regression(LR) and an artificial neural network(ANN) to produce a LSM. The LSM is produced with 11 causative factors and then optimized using forward-stepwise LR(FSLR), ANN, and their combination(FSLR-ANN) until eight causative factors were found for each method. The ANN method produced superior validation results compared with LR. The ROC values for the training data set ranges between 0.8 and 0.9. On the other hand, validation with the percentage of landslide fall into LSM class high and very high, ANN method was higher(92.59%) than LR(82.12%). FSLR-ANN with nine causative factors gave the best validation results with respect to area under curve(AUC) values, and validation with the percentage of landslide fall into LSM class high and very high. In conclusion, ANN was found to be better than LR when producing LSMs. The best Optimization was combination of FSLR-ANN with nine causative factors and AUC success rate 0.847, predictive rate 0.844 and validation with landslide fall into high and very high class with 91.30%. It is an encouraging preliminary model towards a systematic introduction of FSLR-ANN model for optimization causative factors in landslide susceptibility assessment in the mountainous area of Ujung Loe Watershed.

关键词： Optimized causative factor landslide, Logistic Regression Artificial neural network Indonesia

A 3D visible evaluation of landslide risk degree under integration of GIS and artificial intelligence

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Science China(Technological Sciences) 2003年第Z1期46卷 142-147页

作者： QIAO Jianping, ZHU Axing, CHEN Yongbo& WANG Rongxun Institute of Mountain Hazards and Environment, Chinese Academy of Sciences and Ministry of Water Resources, Chengdu 610041, China Geography Department of Wisconsin University, Madison, Wisconsin, USA Chinese Acad Sci Inst Mt Hazards & Environm Chengdu 610041 Peoples R China Minist Water Resources Chengdu 610041 Peoples R China Univ Wisconsin Dept Geog Madison WI 53706 USA

Artificial intelligence has been used to obtain background factors (basic environmental factors) from landslide specialists. A 3D visible evaluation map may be charted by fuzzy evaluation, and the traditional plane map may be decoded into a 3D map by using factor weight from specialists system and technology of RS and GIS for quantitative sampling of these factors.

关键词： GIS technology, artificial intelligence, landslide, visibility.

Rainfall-induced landslide stability analysis in response to transient pore pressure——A case study of natural terrain landslide in Hong Kong

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Science China(Technological Sciences) 2003年第Z1期46卷 52-68页

作者： LAN Hengxing, ZHOU Chenghu C. F. LeeWANG Sijing & WU Faquan State Key Laboratory of Natural Resources and Environmental System, Institute of Geographical Sci-ences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China Department of Civil Engineering, Hong Kong University, Hong Kong, China 3. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China Chinese Acad Sci State Key Lab Nat Resources & Environm Syst Inst Geog Sci & Nat Resources Res Beijing 100101 Peoples R China Univ Hong Kong Dept Civil Engn Hong Kong Hong Kong Peoples R China Chinese Acad Sci Inst Geol & Geophys Beijing 100029 Peoples R China

Transient pore pressure in response to short intense rainfall process plays an important role in shallow landslide occurrence. Using GIS technology, we carry out the rainfall-induced landslide stability analysis in response to transient pore pressure by means of transient and unsaturated rainfall infiltration modeling. A case study is performed on the shallow landslide stability analysis in Hong Kong. Detailed analysis and discussion reached some useful conclusions on the tempo-spatial behavior and characteristics of slope stability response and pore pressure response to typical rainfall process. Comparison analysis is performed on some important issues including landslide stability response in different types of slopes with different hydraulic properties, antecedent rainfall and landslide stability, and the nature of pore pressure response time. These studies might give us an important insight into landslide tringgering mechanism and the hydrological process in response to rainfall, and provide systematic information and evidences for effective risk assessment and warning system establishment.

关键词： rainfall-induced landslide, transient pore pressure, landslide stability in response to rainfall, GIS.

Experimental study on pore pressure in rock-soil slope during reservoir water level fluctuation

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Science China(Technological Sciences) 2005年第Z1期48卷 196-208页

作者： LIU Yuewu CHEN Huixin LIU Qingquan GONG Xin ZHANG Dawei LI Lianxiang Division of Engineering Science Institute of Mechanics Chinese Academy of Sciences Beijing 100080 Division of Engineering Science Institute of Mechanics Chinese Academy of Sciences Beijing 100080 Division of Engineering Science Institute of Mechanics Chinese Academy of Sciences Beijing 100080 Division of Engineering Science Institute of Mechanics Chinese Academy of Sciences Beijing 100080 Division of Engineering Science Institute of Mechanics Chinese Academy of Sciences Beijing 100080 Division of Engineering Science Institute of Mechanics Chinese Academy of Sciences Beijing 100080

A test system was developed for measuring the pore pressure in porous media, and a new model was devised for the pore pressure testing in both saturated and unsaturated rock-soil. Laboratory experiments were carried out to determine the pore pressure during water level fluctuation. The variations of transient pore pressure vs. time at different locations of the simulated rock-soil system were acquired and processed, and meanwhile the deformation and failure of the model are observed. The experiment results show that whether the porous media are saturated or not, the transient pore pressure is mainly dependent on the water level fluctuation, and coupled with the variation of the stress field.

关键词： landslide, pore pressure, reservoir water level, rock-soil.

Synergetic-bifurcated prediction model of slope occurrence and its application

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Science China(Technological Sciences) 2003年第Z1期46卷 69-77页

作者： HUANG Zhiquan & WANG Sijing North China Institute of Water Conservancy and Hydroelectric Power, Zhengzhou 450008, China Institute of Geology & Geophysics, Chinese Academy of Sciences, Beijing 100029, China N China Inst Water Conservancy & Hydroelect Power Zhengzhou 450008 Peoples R China Chinese Acad Sci Inst Geol & Geophys Beijing 100029 Peoples R China

landslide prediction is one of the most important aspects of prevention and control for geological hazards and the environmental protection. In order to study the nonlinear methods for landslide prediction, the synergetic-bifurcated model of predicting the timing of slope failure is established by combining Synergetics with Bifurcation Theory based on single-state variable friction law in this paper. The synergetic effects and bifurcated process of the factors in the slope evolution can be characterized in the model. Taking the Xintan landslide as an example, the prediction of landslide is carried out based on the model suggested.

关键词： friction law, landslide, synergetic-bifurcated model, time prediction.