Study On Geohazard Risk Management Methods In Southwest Mountain Towns Construction

The geological condition in southwest mountains is very complex,on the otherhand, The urban population and economy increase rapidly,the scale of urban expandunceasingly, the geohazard happens frequently.The threaten from geohazard bringsthe serious economic loss and the personnel casualty to the dwellers in mountainsarea,and becomes a big problem for the economic development and sustainabledevelopment.The geological condition in southwest mountains is very complex,on the otherhand, The urban population and economy increase rapidly,the scale of urban expandunceasingly, the geohazard happens frequently.The threaten from geohazard bringsthe serious economic loss and the personnel casualty to the dwellers in mountainsarea,and becomes a big problem for the economic development and sustainabledevelopment. In virtue of southwest mountains suffer serious threatens from thegeohazard and the geological environment condition and the geological disasterrestrict the urban development deeply, this article carries on the study on the methodand process of geohazard risk control, by means of research of geohazardrecognition, geohazard hazard evaluation,risk evaluation,risk management and riskcontrol,at the last,the author set up a systematic method of of geohazard risk controland geohazard hazard evaluation. In this paper, reasonable discussions have beendug into this research area, and major creative outcome has been obtained asfollows:1. Through analysis the relation between the number of deaths because ofgeohazard and the total population each year from2001to2008,through the study onthe acceptable risk level of china had been carried on, and it is the first time to determine the upper and lower limit of acceptabal risk for geohazard inChina.Finally,the FN curve for the acceptable risk level in China had been plotted.2. By collecting and reading a lot of literatures of earthquake induced geohazardwith fieldwork,a thoroughly study had been carried on the mechanism,distributionand rule of seismic geohazard induced by WenChuan earthquake,a total of11factorsin two categories had been selected,and the factors consisted of engineeringgeological rock groups, terrain slope, geologic structure, slope type,relative altitude,river system, profile type, plane type,fault type,the distance from fault,and slopedirection.the geohazard susceptibility index system under earthquake condition hadbeen creative built up.3. The basic framework of geohazards assessment and risk management hadbeen improved,in addition,the objectives, types, basic principles, ideas andimplementation of content in geohazard assessment, vulnerability assessment andmanagement had been described in this paper, at the last,the author set up asystematic method of geohazard risk manage and geohazard evaluation, theprocessing include: definite goal of evaluation and controlâ†'geohazard recognitionâ†'Establishment of geohazard risk information databaseâ†'geohazard hazard evaluationâ†'geohazard risk evaluationâ†'geohazard risk assessmentâ†'research of geohazardrisk management.4. The arrangement, precision and applicability of risk control had been putforward,on the basis of feature of geohazard risk in southwest mountains, thearrangement includes four scale: regional scale(<1:200000), intermediatescale(1:200000～1:50000), local scale(1:50000～1:5000) and site specificscale(>1:5000).5. This evaluating indicator system fully considered history factors,basicenvironmental factosr and the different geohazard triggering factor,such as rainfalland earthquake,a more comprehensive hazard evaluation index system had been builtup for different types of geohazards..6. The models and methods for hazard assessment had been established for thesingle geohazard, the Monte Carlo method had been used for analying theprobability of occurrence of geohard and calculating the likelihood of singlegeohazard.The empirical formula and the numerical simulate method had been usedfor forecasting the affected area after geohazard occurred.7. On the basis of collection of relevant information, the static method had beenused to analyze the relation between volume and run out distance of rapid landslide, On the basis of static method,the relation between volume and run out distance ofrapid landslide had been analyzed, the author built up the linear equation as follow:V=0.2026L+407.91.8. The basic framework of geohazards assessment and risk management hadbeen improved, by considering the actual conditions in Southwest mountain,andconsolidated currently used methods and measures of geohazard risk managementand control A realistic solution for the geohazard risk management has beenprovided as following procedure: geohazard preventionâ†'Pre-geohazardpreparednessâ†'emergency responseâ†'reconstruction,in additional, the content ofeach stage had been detailed described.9. The probability statistical analysis method for the early warning rainfall thatinduced the geohazard had been built up,the first step is to collect rainfall data thatinduced and did not induce the geohazard,the data consisted of the three daysprecipitation before geohazard and The same day precipitation,then according to thedistribution of these data on xy axis, by using the parallel lines to draw the warningbaseline,on the basis of specifying the next envelope curve and up envelope curve.10. By use of these methods above,DanBa county and WenChuan county hadbeen selected as demonstration town to carry on the research of geohazard riskmanagement, The results of case study show that the research methodology from thepaper will be useful to push forward the development of geohazard assessment andrisk management.