Evaluation. The Jinnan Region Loess Collapsible Partition And Its Geotechnical Characteristics

South Shanxi Province area is located in the southern region of Shanxi province, where is widely distributed with the loess layer and the geological harzards of collapsible loess simultaneously. Collapsible loess is made primarily of the Quaternary Pleistocene series loess. Loess is one special type of soil, and collapsible evaluation is its main studying points.Combining Chinese loess area method, according to landscape type and collapsibility evaluation results mainly from the engineering geological properties of loess-pronged approach, the geological engineering properties zoning of collapsible loess in South Shanxi Province area, and the forming causes and developing law of collapsible loess from the origin, thickness, type, grade, and physical and mechanical properties, and so on, is studied systematically in this paper. Noteworthyly, the studying collapsible loess is consisted of all kind of Quaternary Pleistocene loess (silt) which is most widely distributed in South Shanxi Province area. And the collapsibility index used is all from test indoor for the evaluation of collapsibility, the softwares used are the evaluation of collapsibility and statistics on soil test for calculations and statistics.Through a great deal of research, yielded results and understanding are list as follows.(1) The type and grade partition of the collapsible loess in South Shanxi Province area is put forward. And the largest thickness of region's loess os from 80 to 150 meter, of which the thickness of loess is up to 20 or 30meter. The collapsible types and grades is distributed from the grade I non-self-respect to IV-level self-respect.(2) A different partition of collapsible loess in the indicators of engineering geological nature is provided. Besides collapsibility index, the loess water content, dry density and soil classification are main indicators which are indirect reflection of the loess (silt, and silty clay) collapsibility strength.(3) The origin and distribution of collapsible loess in the region is analysed. The loess has various genetic types, having eolian deposit and aqueous deposit, which is greatly different from the eolian loess in the Loess Plateau in western or the aquatic loess in the eastern part of northern China Plain.(4) The strong collapsibility areas is pointed out, and their causes is finded out. The collapsibility and depth of loess in Yuncheng city is higher than its in Linfen district, especially in the high stream terrace and alluvial-proluvial plain before the mountain forming period. The reason is mainly related with the regional characteristics of collapsible loess and soluble salt content of the background value.(5) Thus, the preventive countermeasures on the loess collapsibility is gained. According to local building experience and construction conditions, and other factors, it is suggested that the prevention and control countermeasures should be mainly ground treatment techniques, and be supplemented waterproof measures and structural measures secondaryly.