The Present Situation Of The Loess Collapse Of Geological Disasters In Shanxi Province And The Water Sensitivity Analysis

The loess collapse disasters in Shanxi Province as an example, through to the four city of linfen,, lvliang, changzhi, xinzhou, disasters area of the loess geologic disaster point on-the-spot investigation and analysis of the collected data: No.1 the complex geological environment in Shanxi Province, the loess geological disasters, high frequency and loss is big, which is given priority to with collapse, collapse for more than 73% of the total number of loess geological disasters. Local land form and collapse disasters, weather, hydrology,the influence of geological structure, and with the development of economy in Shanxi Province, the human activities on the influence of geological disaster is more and more big; In addition to the geological disasters have occurred, there are a lot of potential in shanxi loess collapse hazard points. No.2 The occurrence of loess collapse,including the loess soil itself and external trigger factors. The loess collapse and external trigger factors that cause mainly for rainfall, soil freezing and thawing erosion, groundwater, river erosion, human activity and biological activity, etc. The rain on the influence of the loess collapse is the most serious. And rainfall, freezing and thawing as the two factors of the loess collapse in common is: at the beginning of the disaster, thesoil moisture content increases rapidly, not enough to sustain its own gravity,whereabouts, soil formation collapse disasters.In view of the loess collapse of water sensitivity analysis, the three geological disasters county: jixian, yonghe, Lin County disaster points on-site in different water content under the indoor direct index to analyze relationship map of jixian and yonghe county soil sample experiment law are similar, which water content of cohesive force and then, when the boundaries limits maximum,when the moisture content is lower than the boundaries limits, cohesion increases change is not obvious, on the whole, in contrast to the cohesive force of law, showed a trend of increase with the decrease of slow after the first, the boundaries,the two counties, respectively ?CJ is(17±2.00)%,?Cy is(15±2.00)%. And collapse disasters occur, than the boundaries limits, the shear strength along with the increase of moisture content fell sharply, become a cause of disaster. The boundaries limits can be used as a disaster area disaster warning value.Lin County experiment result is: the difference in map of jixian and experimental law of yonghe, moisture content is on the decline, and Angle of internal friction down gently, do little against the shear strength, the reason of the difference is that Lin County loess natural water content is low, large porosity, for stent-macropore loess, soil skeleton strength with structure strength contribution rate is not big, the structural strength mainly depends on the cement between particles and the properties of the crystal structure. Cement is mainlycalcium carbonate, and is composed of machine quality, and the crystal structure is mainly composed of inorganic salts, these substances of soluble salt a, cement and crystal structure of loess breakup, cohesive force; The countries of jixian and yonghe loess high natural moisture content, low porosity, the cementation between the state of natural soils intergranular by organic matter, carbonate and free oxide colloid link together, usually the cementation was conducted soil particles cannot fully play its role, lower soil cohesion; With water content increasing, the cementation force increases, thus increasing soil cohesion; Water content continues to increase, the colloid will gradually be dissolved in water,the cementation gradually disappear, lead to decrease of soil cohesion.