Study Of The Red Beds Water-rock(soil) Chemical Interaction In The Slipping Zone

Nanjiang County,which is located in the northeastern part of the Sichuan region,the south central of the county is a typical red layer area,2011 "9.16" due to the impact of heavy rainfall,the region occurred thousands of soil landslides,mostly are Slow-inclination shallow soil landslides.And the evolution of the landslide is a series of extremely complex physical-chemical changes,especially the geochemical conditions at the slip zone which are closely controlled by the formation and aggregation of the "slipping soil".Affecting the development and evolution of landslides.The slip soil is an important product of the formation,development and sliding process of the landslide.It is also an important part of the landslide.The formation and aggregation of the slip soil are closely related to the development and evolution,the deformation history and the stability of the landslide.By the methods of field investigation and a large number of indoor tests,this thesis study the occurrence conditions of slip soil,and combing with the basic principles of hydrogeochemistry to analysis about water-rock(soil)chemical interaction of the whole process of stepwise evolution;which including the bedrock to compresso-crushed zone to softened intercalated clay layer and to slipping soil,and discussed the influence process of the slip belt by changing environment on the sliding zone..The slip soil,as a relative aquifer,can intercept the upper infiltration precipitation and form an independent hydrogeological unit.At the same time,the claying process of the rock-forming minerals tends to form a Relatively "open" and "close" environment,in such a relatively closed environment,due to the environment of microbial respiration,etc.,to form a hypoxic reducing environment.Based on the composition of the elemental composition and mineral of slip soil and upper soil and bedrock,combined with the basic hydrogeochemical principle,it can be seen that during the formation of slip zone,the most important role is the clay mineralization process.The degree of mud layering is increasing,so that the continuous slip zone is formed in the slope.The oxygen environment and the environment without oxygen were used to simulate the environmental changes of the slip zone and the influence of the slip soil.In the oxygen environment,the main manifestations are: during the early stage of the test,low valence of the metal element oxidation,and the addition of lower concentration solution to groundwater increased the soluble salt solubility,so that the solution SO42-and Cl-Concentration increased,combine to the H+ ion which caused by the oxidation form acid substance,making the solution PH value decrease.However,the subsequent conversion of the silicate minerals and the dissolution of the carbonate minerals in the system causes the pH of the solution rise and produce alkalization.In the environment without oxygen,the dissolution of soluble salts and the slowly conversion of the silicate minerals,namely,the conversion of illite to kaolinite,which is better chemically stable,is present in the aqueous solution.So the PH value of the main slope is relatively small steady upward trend.According to the analysis of the attenuation degree of the shear strength of the sliding soil in different environments,the mechanism and process of the landslide are discussed based on the example of the large number of landslides induced by the "9.16" heavy rainfall in the Nanjiang area in 2011.The continuous rainfall is not only changes the reduction environment of slip soil,groundwater infiltration and slip soil oxidation reaction,so that the accumulation of clay minerals,but also the low concentration of groundwater participation,makes the soil cement dissolved,making The shear strength of the slip soil decreases and the thickness increases.and the barrier effect of the clay minerals in the sliding zone increases the load of the slope.because of the reduction of the shear strength due to the chemical action caused by the rainfall on the sliding zone is a longer-term effect,and need a strong rainfall so that the slope of the load increased to a certain range,it can be inferred that the rain storms after a long rain is the necessary condition which causes the such Slow-inclination shallow soil landslides large-scale mass occurrence in red layer.