Research On The Development And Integration Technology Of Landslide Stability Evaluation System Under Distributed Environment

China is a mountainous country with a vast domain.The geological environment of some region is very complex. Suffering from weather, human engineering activities, flow or raise of the water level of the river, Landslide happens frequently. Landslide stability analysis is an important research subject in the field of landslide disaster prevention.Currently, the main means of the landslide stability analysis is to work out the safe factor of the landslide with the software developed based on limit equilibrium theory.However, most of the existing landslide stability analysis softwares can be only used in single application environment and are isolated from other systems, so not only the data, function and application can't be shared, but also the interactive operation with other system can't be implemented. It is not only an urgent subject of landslide prevention field but also the new requirment of landslide treatment design to develope the landslide stability evaluation software, which can work collaboratively with other systems, taking the distributed environment into account and combining distributed software technology, WebGIS technology and network database technology. Based on this idea, the development and integration technology of landslide stability evaluation system under distributed environment is explored, and theoretical methods and key technologies are studied in this thesis. The research results are converted into the practical software system available to verify the practicality of the results. The main research contents and results of the thesis are as follows.(1)A WebGIS framework based on Web Services is proposed after the principle and implementation technology of WebGIS is studied. The visiualization, storage and geometry spatial operation of landslide profiles are implemented by WebGIS, so WebGIS platform is very important for the development of limit equilibrium method procedure.Taking the characteristics of the distributed environment fully into account, a framework for low level WebGIS platform based on the Web services is proposed.GIS function and database operation are shared by encapsuling the GIS module into web services and publishing them to the service registry for the users to find and locate. (2)Combining Ajax and dynamic image generation technology together, a map generation engine is proposed to achieve the visualization and efficient interactive browsing of landslide profile model. Firstly, vector graphics is drawed to the image data buffer. Then the data is compressed and converted into an image. At last the image is sended to web client. So the web client can display it as a photo and this decrease the load of client a lot. The response of map operation is always slow in tradditional WebGIS, and Ajax is used to solve the problem in this thesis.In this case, the network only transmits the interaction data, not the entire page. So the bandwidth of the network is saved a lot, user experience is improved and operation of web software is close to desktop appliations, because at that time the client can still carry out other operations.(3)The theory of spatial geometry relationship operation is studied. The data structures are designed and the methods of spatial geometry relationship operation are described. Spatial geometries are classified as point geometry, line geometry and polygon geometry. The spatial relationship of geometries is defined as Disjoint, touches, crosses, within and overlaps. The spatial relationship operation algorithms are described in the thesis.(4) Based on limit equilibrium theory, the calculation formulas of Fellenius, simplified Bishop, janbu, Sarma and transfer coefficient are deduced.Then the key algorithms in stability evaluation are studied, including the algorithm of constructing profile from boundary line and soil layer line, the algorithm of slip region slicing and the algorithm of searching of the most dangerous slip region etc.(5) The integration technology under distributed environment is studied. Based on SOA, seamless integration between heterogeneous systems is achieved by developing adapters.Functions needed to be shared are encapsulates in adapters and database operation is encapsulates in unified data operation interface.(6) Data extraction method under distributed environment is explored. A data extraction engine which can find the available and valid data from the mass of data in the distributed database is designed and the key components of which are described. The rich data in low-level database is clustered by ELECTRE method and then classified according some rules. This provides a useful thought for extracting calculating parameter from data source for landslide stability evaluation. (7) Based on the research results of the thesis, landslide stability evaluation system WebTGLses is developed independently.The system is based on the WebGIS platform which is fully self developed and implements the 5 stability evaluation methods mentioned in the thesis. It can analyze the stability of landslides in a variety of situations and the calculation results can be analyzed statistically.As a result of the integration technology based on SOA, WebTGLses is integrated with the geological disaster and emergency command decision support system of Three Gorges Reservoir Area, scene roamingin of three-dimensional geological disasters and other geological disasters prevention and control software system successfully.