Study On Project Impact And Development Features Of The Red Layer Of Karst Of The Venue

Sichuan red basin is karst development. According to the Sichuan Jiajiang red layer karst (pore) hydrology geology of a field survey in the encounter, and affect the development characteristics of karst and its construction. Based on the analysis of physical geography, stratum lithology and based on the hydrogeological. Investigation of karst petrological properties, morphology and size, filling material; statistical analysis based on the spatial distribution of karst, the karst development characteristics; through the dissolution of gypsum salt rock analysis, factors affecting the dissolution rate of karst site; through the hydrological geology characteristics of site analysis, formation the study on karst groundwater numerical simulation; finally, development and research of karst dissolution and inversion of hydrogeological conditions, the effect of the influence of karst development project. This research mainly obtains the following conclusion:(1). The study area is located in the Cretaceous Guankou formation silty mudstone and mudstone area, the whole area is located in the Sichuan depression of the Yangtze paraplatform in Western Sichuan depression in the southern part of Taiwan, the regional geological structure to the ne structure system is the main body of Nanan syncline and F2 overthrust fault is the main research of geological structure in the area. Terrain to tectonic denudation landform, and belongs to the low mountain and hilly terrain, undulating terrain. In the Qing Yi River wood City, near Nanan, a terrace with river deposition. The study area in the period of Yanshan movement in the late Early Cretaceous, become an inland saline lake. This period of the late Cretaceous Guankou formation (K.2g) formation is a set of distinct Salt Lake red river sandstone and mudstone. Gypsum salt contained large amount of silty mudstone and muddy siltstone red strata. Groundwater is mainly pore water in the eluvial slope and weathered zone fissure water and structural fissure water network, shallow weathered zone fissure water is the main types of groundwater in the yard. The southwest side of the highest field region, mainly by atmospheric precipitation, middle is the vadose zone groundwater, excretion to Yan Xi, in the area with strong seepage. Surface water is not development.the atmospheric precipitation is the main recharge sources of groundwater field. The water chemistry cation with Ca2+ ions to HCO3- ions, anions.The groundwater in the three line of the distribution is more concentrated.(2). Form field of red beds are mainly gypsum karst spots, pores and caves. Pores (pore) is the most important in the research area of karst forms the most typical, in accordance with the filling ingredients are different, divided into the tunnel wall crystal filling, mud filled, gravel filling. Due to associated development conditions, dissolved pore and dissolved pore and structure divided into primary pores. In the form of underground karst development pattern, gypsum spots, solution pores and caves. On the basis of developmental type and intensity, the degree of harm, the plane distribution of karst is divided into three areas. As the main material of gypsum salt rock, vertical distribution is layered and pulse shape. The vertical pores are common and the concentration of the characteristics. Analysis area of the karst development pattern and geological structure and groundwater seepage and distribution characteristics. But overall, growth is small, the scale is limited.(3). Gypsum salt (gypsum, Glauber’s salt, calcium salt) is an important material field of red layer of karst formation, to study the mechanism of karst development in the study area, which is analysis of the effect on the dissolution of gypsum salt rocks. Petrological component analysis method with thin section identification method and chemical analysis method, preliminary analysis, silty mudstone and mudstone containing gypsum salt field area is the main rock, the main factors of difference between the two is not dissolved pores formation lithology. The erosion rate and erosion morphological development and gypsum salt solution pore, dissolution experiment is the main controlling factors of influence from the dissolution of karst formation, two group experimental design scheme of experimental (hydrostatic and hydrodynamic conditions), data obtained by experiment, to analyse the relationship between the time, weight, material content and alkali dissolution concentration, in order to reflect the dissolution of gypsum salt. According to the experiment results, the seepage of groundwater plays a major role in the formation process of karst in carbonate rock, is different from the single chemical karstification, containing gypsum salt dissolution of red layer exist at the same time chemical and physical effects of two kinds of process, effects of the interaction between the two, and promote each other. Groundwater is the result of dissolution of karst and handling latent corrosion results of the formation of karst.(4). Karst development leads to rock mass seepage channel in addition to the conventional structure of weathering, and because Karst (pore) of groundwater seepage formation, water pressure test is an effective way to obtain the formation of hydrogeological parameters. According to the current development of fissures in case of using model inversion method, based on the analysis of initial water level and various parameters, to fit the site groundwater initial flow field. From the model space red layer that karst development characteristics and corrosion mechanism, test the water pressure test to reflect the actual effect.In addition, three dimensional numerical simulation of the site.also can provide guidancement on the future of the anti-seepage treatment.