| Mudstone in Triassic Badong formation belongs to the category of red-bed soft rock.It is characterized by its significant dilation and disintegration property in contact with water due to its rich content of hydrophilic clay minerals like illite and montmorillonite,which makes it the typical“sliding stratum”.Landslides of Badong formation within this stratum with characteristics including wild distribution,high occurring frequency,heavy catastrophic influence and high burstiness have always been the restriction towards regional construction and economic development.For example,Xuanen area,Enshi state of Hubei province.In terms of regional geo-hazard prevention,General Secretary Xi once stressed that information engineering of monitoring and early warning towards natural disasters should be implemented to improve the capacity on comprehensive monitoring of multiple disasters and disaster chains,early risk identification,prediction and early warning.The core of this problem is to figure out where the hidden danger is and when the danger will occur,upon which the early identification of landslides will be realized in order to highly improve the efficiency on disaster prevention with pertinently propose decision-making.Based on what is mentioned above,this thesis was composed with the guidance from engineering geology,rock mechanics and information engineering.It combined geological investigation,Arc GIS analysis and graphing,laboratory experiments,mathematical modeling and Cloud platform development and other technologies,to carry out the research on the landslides distribution,early identification system,deformation control decision-making and design of Cloud platform against the landslides of Badong formation in Xuanen area.Above all,this thesis has emphatically analyzed the distribution features of Badong stratum upon ascertaining the regional geology background in the researched area.The evolving regularity of landslides was depicted from four perspectives including the landslides scale,thickness of the sliding body,mode of motion and the current stability.The distribution features of landslides in researched area were analyzed from time and spatial dimension.There were three main regional outcrops of the Badong stratum with total area of 127.08km~2within Xuanen County,taking up 4.64%of the total area of the county.110 landslides were developed in the Badong stratum,taking up 30.56%of that in total.Landslides of Badong formation were mainly superficial and in small scale,and the motion mode of which was mainly tractive while most were basically stable.Half of the landslides of Badong formation administratively lied on Wanzhai Town.Most of the landslides were located in the low-relief terrain in terms of elevation distribution,and the slope rate of which was mainly gentle.97.23%of the landslides were more than 1500m away from the closest geological structure,and 25 of all landslides were located in the200-meter-wide area that the hydrographic net affected most.The land-use type of the landslides was mainly forest that mostly distributed in the area with annual precipitation between 1340mm and 1360mm.The majority of the landslides of Badong formation,85in total,occurred during June to August with full precipitation participated.Secondary,this thesis carried out the regional hazard zoning and evaluation of landslides of Badong formation under different scales,and verified the evaluation results through ROC curve.Upon generalizing the types of engineering geology for landslides of Badong formation,an elaborate identification method narrowing down from the entire county to crucial region and to a specific landslide was obtained.Regional representative factors should be selected to form an evaluation system for small plotting scale landslide risk evaluation in county region,and grid units with a wider range should be selected as the basic evaluation unit.The evaluation results showed that the landslide risk division in Xuanen area was mainly medium and low risk,accounting for 75.35%.Slope structural representative factors should be selected to form an evaluation system for large plotting scale landslide risk evaluation in crucial region,and slope units should be selected as the basic evaluation unit.The evaluation results showed that high and ultra-high risk area accounted for 47%of the total area of the Badong stratum,mainly distributing in the north parts of Wanzhai Town,the neighboring area between Jiaoyuan Town and Zhushan Town and the west and southeast part of Zhushan Town.The AUC of the area under the ROC curve of landslide risk in Xuanen County and the crucial region in Badong formation was0.821 and 0.754,respectively,indicating high accuracy of the evaluation result.Analysis of multiple factor contribution rate showed that the factor sensitivity for landslides of Badong formation was in the following order:rock dip angle>slope structure>difference in elevation>slope rate>hydrographic net.The four engineering geological models developed by this method covered nearly 80%of Badong formation landslides.Elaborate identification method scaling down from the entire county to crucial region and to a specific landslide is able to solve the question that where the hidden danger is.It is the first step of the identification system for landslides of Badong formation.Then,this thesis selected the typical single landslide of Badong formation as the research object,carried out the research on the engineering geological evolution and staging classification of single landslide based on"slip belt-slide body",and formed the early identification system for landslides of Badong formation in Xuanen area from"regional elaborate identification"to"landslides evolution stage identification".The uniaxial compression test of mudstone showed that the mudstone in Badong formation stratum in the slip zone was soft rock,and the strain-time curve of creep test showed that the deformation and failure of mudstone experienced three stages:initial creeping stage,constant velocity creeping stage and accelerated creeping stage.The variation of the displacement,stress and energy of the sliding body revealed that the deformation of the sliding body had undergone three stages:initial deformation stage,constant velocity deformation stage and accelerated deformation stage.The distribution characteristics of cracks could be a typical deformation indicator for the identification of the landslides.The identification of landslide evolution stage based on"slip belt-slide body"could solve the problem of“when the danger will occur”,so that pertinent prevention decision-making could therefore be made.Next,this thesis put forward the decision-making system for landslide deformation control based on the stability states corresponding to the characteristics of different evolution stages of the landslides,and carried out the deformation-controlling mechanism and detailed decision-making for the landslides in different evolution stages.For those landslides in the stage of constant velocity deformation that do not need immediate prevention measures,the monitoring scheme of the key position of landslide deformation and the key time of prevention and control should be determined based on the analysis of the spatial and time effects.For those landslides in the stage of accelerating deformation or failure,stress-reducing model for soil arch under the interaction between sliding body and stabilizing piles showed the stress between piles exhibited exponential reduction.The landslide thrust load sharing model showed that the landslide thrust load was shared in three phases.The optimization of critical pile space model determined the optimization of stabilizing design,and has been applied in practical engineering well.Finally,based on the research outcomes of basic geological theories,the thesis preliminarily designed the cloud platform for landslides of Badong Formation in Xuanen area with cloud computing,network function virtualization and multiple heterogeneous storage databases as the key technologies.The cloud platform could meet the requirements of landslides survey data management,application of landslides early identification,effective decision-making of deformation control,rapid information sharing and other aspects.It not only had the functions of big data collection,processing and analysis of landslides database under cloud computing,but also had the ability of early identification for landslides and prevention decision-making based on the basic theory of geomechanics.The platform could provide a reference for the construction of cloud platform of geological industry,and have certain guiding value for regional disaster prevention. |
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