Application of Revised BP -NN Method to Landslide Stability Analysis in the Three Gorges Area

Using the revised BP-NN,this paper presented the neural network method for landslide stability analysis in the Three Gorges area.By choosing 30 typical landslides in this area as examples,the stability state estimated by the revised BP-NN method is highly consistent to that by conventional transfer coefficient method.And the method presented in this paper has following advantages:the input parameters are easily obtained and this method does not deeply rely on investigation quality and shear strength parameters of slips and is a quite simple one.The BP-NN method is a new measure to stability analysis of landslides in the Three Gorges area,which is especially suitable to the stability prediction of landslides before investigation.     

Experiment Study on Soil Properties of Shennv Stream Landslide in Wu Gorge

Accurate obtainting soil parameters of landslide is the key links for landslide stability evaluation and project management . This article takes Shennv Stream landslide in Chongqing Wushan County as an example, implementing unconsolidated and undrained shear test and mineral composition analysis by X ray diffraction for soil in different elevations of landslide ,conducting sensitivity test for various soil parameters of reservoir landslide change with different water level.Study shows that : Mineral composition of soil mainly contains Calcite, Quartz and clay mineral. Hydrophilic minerals in clay mineral have great effect on stability of landslide. Shear strength decreases by influence of water content on cohesion. Cohesion decreases sharply in a quadratic function relation with water content increasing .When water content comes to 18.21% ,change of cohesion tends to be stable.But the internal friction angle of landslide soil decreases linearly in small amplitude with an increase of water content. Research results may provide some important references for rationally choosing strength parameters of soil in similar landslide.     

Improved Information Value Model and Its Application in the Spatial Prediction of Landslides

Information Value Model is used frequently in domestic landslide hazard zonation prediction, which plays a very important role for land-use planning especially in mountain area. Through theoretical analysis, the prerequisite of Information Value Model which should be used with influence-factors independent from each other is studied. Factor Analysis is adopted to evaluate and eliminate the influence of correlation between influence-factors in spatial prediction of landslides which are showed through case study. Relationships between landslides and influence-factors are studied based on a certain watershed in which the Information Value Model and Factor Analysis are applied. The probability of landslides changes regularly with the influence-factors, and based on which a method for the discretization of influence-factors is advised. The distribution of landslide susceptibility of above watershed is calculated and validated based on the area-ratio index with landslides occurring in nearly 5 years, which proves the credibility of Information Value Model.     

Analytical and Calculative Method of Stability of MingShan Landslide in the Three Gorges Reservoir Area

After the dam of the Three Gorges is built, the raising water will inevitably cause the revival of the part of ancient landslide and the generation of new landslide ,which will influence the town development and traffic safety in the Three Gorges Reservoir Area. In the light of the specific conditions of the Three Gorges Reservoir Area, this paper, taking Fengdu's MingShan landslide in Chongqing for an example, has considered ten typical calculative projects, offered the correspondent load systems acting on the sliding mass and put forward the analytical and calculative method to evaluate the stability of a landslide. The ten typical calculative projects include dry season(natural state), raining season (rainstorm or rain for a long period of time), dry season and water level (175m ) of the reservoir, raining season and water level (175 m) of the reservoir, dry season and earthquake, raining season and earthquake, dry season and water level (175 m ) of the reservoir and earthquake, raining season and water level (175 m) of the reservoir and earthquake, dry season and water level lowered from 175 m to 145 m, raining seasons and water level lowered from 175 m to 145 m, and so on.     

Monitoring and deformation analysis of pushed landslide changing water level in the Three Gorges reservoir

The typical pushed landslide deform becomes stronger when water fills in the Three Gorges reservoir. In order to better recognize the landslides deformation characteristics and prevent the disaster by the water change regulation, the paper takes an example of the features of geological conditions and deformation of Liangshuijing landslide in Yunyang which is the typical pushed landslide in the Three Gorges reservoir, and designs monitoring project. Through monitoring data including the surface displacement, ground fissure, deep displacement, ground water level, rainfall and macroscopic patrol, the variety law and relationship among monitoring data are obtained. The regularity of landslide deformation and its deformation velocity are concluded when the variation of the rainfall and water level change. Combined the variation of bands-stabilization coefficient, deformation laws of the pushed landslide by the rainfall or the reservoir water are obtained. The deformation caused by rainfall is large in the back landslide, while the deformation caused by hydrodynamic pressure is large in the front landslide. The higher the water level, the severelier of the influence. The deformation is largely influenced by hydrodynamic pressure when reservoir water declines sharply in the front landslide, and the deformation is the largest when rainfall and reservoir sharpe water decline happened simultaneously in the whole landslide. The law provides scientific basis for reduction and prevention disaster of the pushed landslide.     

Fuzzy Comprehensive Evaluation on Landslides Risk Assessment Induced by Extreme Rainfall

The hazard assessment of the highway landslide induced by the extreme rainfall is a complicated systemetic issue.By combining the modified analytic hierarchy process and the fuzzy comprehensive evaluation,all the factors that influence the highway landslide are analyzed.And the comprehensive evaluation index system as well as the danger rating is established.In the process of evaluation,different rainfall's dynamic weighting system is fixed,and then the membership of continuous and discrete index are calculated respectively by using the trapezoid membership function formula and expertise assignment,and finally case study is carried out.It is shown that this method is suitable and rational to evaluate the highway landslide induced by extreme rainfall.     

Analysis on Effect of Traffic Loads on Landslide Stability

In the design of landslide control engineering,the effect of traffic loads has not been taken into account.The authors simplified the traffic loads as mobile dead loads and traffic dynamic load.The mobile dead load ranges from 2.34 to 6.41 kPa.The impact coefficient was chosen to denote the traffic dynamic load and ranges from 0.1 to 0.4.Using several stability analysis methods widely accepted by engineers,combining two analysis samples,by the contrast of stability tests with and without consideration of the mobile dead load or the traffic dynamic load,the authors found that when the traffic load is not taken into account,the stability coefficient of shallow layer landslide(<8m) is overrated by 4.3-11 percent or 5.8-12.1 percent in comparison with the case when the mobile dead load or traffic dynamic is taken into account respectively,that is,the influence of mobile dead loads and traffic dynamic load is cannot be neglected.In case of medium deep layer landslide or the road is passing through the anti sliding section,the influence of the traffic load is a little and can be neglected.     

A Calculation Methed for Failure Probability of Typical Element at Landslide Risk

From the point of view of system theory, the landslide hazard system includes two subsystems: subsystem of hazard and subsystem of stricken. The consequence of landslide hazard is based on the interaction of these two subsystems. previous studies concenerate on evaluation of landslide stability. Hence, the study of a typical element at landslide risk is focused. And a method to calculate failure probability of typical element (frame structure) at landslide risk is discussed. Furthermore, the influences of both impact force and impact resistance capability of element at risk on failure probability are analyzed, which shows that, for each elements at risk, the landslide impact area can be divided into absolutely dangerous zone, relatively dangerous zone and absolutely safety zone. In addition, with the condition that the structure failure probability is above 50%, as the variability of impact force increases, the structure failure probability decreases; with the condition that structure failure probability is below 50%, as the variability of impact force increases, the structure failure probability also increases.     

Key Problems Controlling the Geological Hazards in the Three-Gorges Reservoir Area

The geological hazards poses a serious challenge to the ecological system in the region of the Three-Gorge Reservoir area, including landslides, rockfalls, debris flow and water quality control. This paper presents a systematic analysis of the key problems in controlling the geological hazards in the Three-Gorge reservoir area with focus on problems of landslides and rockfalls, and proposes solution measures in four main aspects: 1) development of reliable laboratory testing and field monitoring equipment and technology which can measure the hydro-mechanical properties of potential sliding surfaces, so to determinate the shear strength of a sliding landmass and its controlling parameters, especially over long periods of time and varying hydraulic conditions; 2) development of reliable methods of characterization of the water-level fluctuations of the reservoir as well as the vulnerable landmasses on its banks, and to standardize the methods for stability assessment of rockfalls and landslides with site specific geological and climatic conditions, and to provide the theoretic al foundations for predicting landmass movements and engineering measures for their prevention; 3) development of reliable in situ long-term monitoring technologies which can automatically and continuously collect the varied changes of key physical parameters controlling the evolution of moving landmasses, so to prepare the pre-sliding warning alarm information in time; 4) development of theoretical analysis tools based on the modern theory of nonlinear and irreversible processes, which is used to study the failure mechanism of rockfalls and landslides and their control methods.     

Stability Analysis on Excavated High Slope of Mozong River Power Station in Wulong

The subject matter of this paper is to analyze the stability of excavated high slope. On the base of typical engineering case in Wulong, Chongqing, the geological conditions and potential failure pattern of the high slope are discussed. Then, the limit equilibrium method and the stereographic projection method are used to synthetically analyze the stability of excavated high slope. As a result, it indicates that the stability of the high slope in insufficient and some retaining structures ought to be adopted for the high slope as soon as possible.     

Data Collection and Control Discuss of GPS Technique and Its Application in Landslides Monitoring

Water level has risen considerably since the impounding of the Three-Gorges Reservoir in year 2003 and that might cause serious geologic hazards, including landslides. Primarily using GPS technique, the landslides wireless monitoring in the Three-Gorges Reservoir is developed in rapidnly. To collect data and monitor in engineering more rational, the system model of GPS technique and its application in landslides monitoring are analyzed. Focusing on the data collection in monitoring, the authors discuss the method of embedding control in the monitoring model. By connecting the character of the monitoring system and landslides, the control signal is produced. At last, the experiment is performed with analogy software in monitoring system including control. The experiment indicates that the control signal is reasonable and valid. In actual engineering, this method is made progress.     

Characteristics Analysis and Control Studying About Panluo Iron Ore Mine Landslide

An analysis about development characteristics of Panluo iron ore mine landslide has been made, and main factors for landslide stability have been gained. According to these factors and development laws of the landslide, some reasonable control measures are put forward, the landslide has been controlled readically after these measures implemented.     

基于信息扩散理论的重庆地区高温风险分析

为了了解重庆地区的高温风险规律,减少该地区高温引起的灾害损失。利用重庆地区34个地面气象观测站的气温观测资料（1981—2010年）,结合信息扩散理论模型,分析了重庆地区的高温风险及成因。结果显示：重庆地区的年平均最高气温、高温日数随时间呈现线性增加趋势;重庆有3个极端高温与高温日数易发高值区;且重庆地区4个区域的高温日数风险差异幅度较大,在高温度数风险概率研究中,重庆4个区域均在36℃时风险概率值达到最大值,黔江所代表区域具有较高的稳定性,高温事件发生的风险概率小;从高温灾害风险空间分布来看,随着高温等级的升高灾害发生的区域面积也相应地减小。基于此,为重庆防灾减灾提供理论依据和参考。     

重庆市RDLS与人居环境地形适宜性评价

“重庆五大功能区”范围的确定,人口因素是不得不考虑的。从地形起伏度方面探索人口分布的规律,进一步佐证重庆市五大功能区划分的科学性。采用重庆市1:250000 DEM数据、2010年分县人口数据,以Arcgis9.3为基础软件,运用邻域分析的方法,计算出了栅格格式的RDLS,单元大小为1 km。RDLS的空间地理规律以及它和人口地理分布的关系,主要从地理空间、构成状况和海拔高度等方面考虑。分析显示：RDLS值主要集中在中低值,RDLS值小于1.5的区域占重庆市总面积的78.82%,累积人口数量占总人口数量的66.37%;RDLS值较高的地区主要集中于渝东北生态涵养发展区和渝东南生态保护发展区;海拔与RDLS呈现出正相关;RDLS曲线和人口密度曲线呈现出高拟合度,通过以RDLS为主要考虑因素,对重庆市地形适宜性做出了评价。

     

Nonlinear Science and Control about the Geological Hazards in the Three Gorges Reservoir Area

Such the geological hazards as landslide, rockfall, debris-flow and so on frequently occur in the Three Gorges Reservoir Area, so it is a very practical and immediate job to explore the mechanism caused the geological hazards and how to forecast and control the geological hazards. For this reason, this paper introduces the situation of the geological hazards occurred in the Three Gorges Reservoir Area and the major type and feature of the geological hazards occurred in Chongqing, and discusses the basic principle about the modern nonlinear science applied to the geological hazards and the creep-slip, stick-slip occurred on the joints of rock mass and the monitoring technology of the geological hazards.The basic thinking is put forward which can be applied the modern nonlinear science to the geological hazards occurred in the Three Gorges Reservoir Area.     

Violent-slide rock avalanche and excitation effect of perilous rock

The physical model of perilous rock avalanche excitation effect is deudofed based on the effect of the main factors, such as weight and fissure water pressure. It quantizes the interaction of perilous rock masses through the energy point of fracture mechanics and wave theory, and gains the departure rate formula of landslide body at momentary avalanche. The particle displacement rate calculation method of perilous rock medium under the action of excitation waves is developed based on the formation of perilous rock avalanche excitation waves and the spread mechanism in slope rock formation. The example shows that the analysis results established are coincident with actual situation. Some scientific basis is provided for the further research of perilous rock damage and evolutionary mechanisms.     

Development and Application of Small Urban Watershed Storm Runoff Model in Mountain City

The small urban watershed storm runoff model of mountain city, which bases on the hydrological method and ArcEngine extension programming was developed aim at stimulating the flood situation, locating the flooding area, computing the subsiding time of flood, utilization and management of the stormwater through the rainfall data. The model was used in Panxi basin of Chongqing. The simulated situation showed that the Nash-Suttcliffe coefficient Ens is 0.56-0.76, the relatively error is 8.82%-11.8%. According to the parameter sensitivity analysis the most sensitivity parameters of the model are width of subcatchment, slope, manning coefficient and impermeable area rate. The model had analyzed the flow, full degree and number of overflowed wells to evaluate drainage capability of drainage system. Results showed that 0.52% of the drainage pipes were overload under one-year storm; compared with 5.86% and 8.20% under fifty-year storm and one-hundred-year storm respectively. By comparing the flow depth inside the wells with the placing depth the assessment results showed that 0.72% of the wells had spillover under one-hundred-year storm and 0.31% of the wells had spillover under one -year. Overall the model achieves effective management of storm runoff and assessment of the water drainage system capacity in mountainous city.     

基于GIS的重庆农业气候资源空间分布精细模拟研究

针对重庆地区地形复杂,气候资源立体多样性明显的特点,本文将经纬度、海拔、坡度、坡向、地形遮蔽度等地理因子引入到气候空间模拟中,采用多因子日照时数模拟和小网格法建立重庆光照、热量和降水等农业气候资源的数学推算模型,在ArcGIS平台支持下,对模型进行了空间精细推算和可视化表达,并将其与常规的回归法与克里格法进行了对比分析。结果表明多因子日照模拟法由于充分考虑了坡度、坡向、日照遮蔽度等下垫面因子对日照的影响,在日照时数模拟方面能够获得较好效果;而年均温、 10℃积温采用Spline残差插值的小网格方法效果更好;年均降水量则以采用IDW残差插值的小网格方法为佳。在此基础上,对重庆地区农业光、热、水资源空间分布的基本特征进行了分析。研究成果可以为充分利用区域气候资源,合理布局农、林、牧产业,实现农业可持续发展提供有效的数据依据和科学支持     

Experimental Study on the Shear Distortion of the Discontinuity of ZHAIBA Landslide in the Yunyang City

In order to analyze the stability of the landslide, it is important to make the shear strength test to discontinuity of the landslide. So, we must use a method of simpleness, practicality and speediness to determine the shear strength of the discontinuity. Using homemade shear equipment, the authors make shear strength test to model from landslide of ZHAIBA under different situation. After analyzing the experiment data we conclude that the shear strength of the discontinuity is relevant not only to compressive force but also to containing water of the discontinuity, Shear strength will rise as compression force rise and will reduce as containing water of the discontinuity rise.     

ANN Disaster Identifying of Wujiawan Landslide in Wanzhou Urban

The paper aims at ANN disaster-possibility identifying of Wujiawan Landslide. ANN construction and parameter setup are analyzed for landslide disaster identifying by ANN, based on a typical landslide-Wujiawan landslide in Wanzhou urban, by confirming evaluation factor and establishing sample data. The ANN model is trained by the similar landslide sample in Wanzhou urban, then the disaster is identified in several different conditions of Wujiawan landslide. Finally, the same conclusion are found by analyzing combined ANN Disaster-Identifying and limit-equilibrium-method calculation. The results show that AAN is accurate and satisfied to be used landslide disaster-possibility identifying.