Research On Vulnerability Of Geological Environment And Its Engineering Response In Changsha City

In recent years, with the rapid development of economy and strong propulsion of urbanization in Changsha city, the vulnerability features of engineering geological environmental have appeared unceasingly. Therefore, it has important theoretical significance and practical value to survey and evaluate the main characteristics and suitability for engineering of urban engineering geological environment. Based on the data collection, field investigation and comprehensive analysis, the vulnerability characteristics of urban engineering geological environment in Changsha city are systematically researched, the report concludes follow:I. The background conditions of urban engineering geological environment are comprehensively analyzed, the most widely distributed stratum are Cretaceous and Quaternary in Changsha. The geological structure is relatively complicated, the NE and NNE faults are dominated. The diversity of rock mass engineering geological properties is much greater, the geological conditions are relatively complicated.II. A systematic diagnosis on the vulnerability engineering geological environment is finished.the Small-scale soil-type slope geological disasters are widely developed in Changsha city, most geological disasters take place in just the rainy season from April to July. Most geological disasters distribute in the foothills and in quaternary unconsolidated rock-types place along the river terraces, mainly distribute in the following slope zone with an altitude of300m, mainly take place in the zone distributed shallow metamorphic rock and granite of Sinian, Banxi Group, Lengjiaxi Group.The surface subsidence are extremely developmented in Meitanba area of Ningxiang Couty. There are561sites where geological disasters, including398karst collapses,110ground uneven settlement,47ground fissure. The disaster-causing factors are not only natural factors but also the main trigger factor that a large number of exhaust or drainage groundwater and deformation in the process of the underground coal mining. Special soil mainly has soft soil, quicksand, red clay and artificial fill. As far as urban construction is concerned, foundation treatment is difficult, the project cost is high and building foundation suitability is difficult.III. On the basis of qualitative analysis, adopting the quantitative analysis of "comprehensive geological disaster risk index method", useing MapGis spatial analysis function, according to the unit information stack, the geological disaster division into districts are carried out. the results showed that the geological disaster frequently occurs in the northern and southern Liuyang city, the eastern Changsha county, the southwest Ningxiang County.IV. Using AHP (analytic hierarchy process) and fuzzy evaluation method, the urban construction land suitability evaluation of geological environment are carried out. the results showed that the urban construction land suitability of geological environment is divided into best suitability, general suitability, seak suitability.