Study On The Complete Compaction Curves And Strength Characteristics Of The Cohesive Soil

Three kinds of cohesive soil form subgrade fillers in Hu-Nan Province was research object to get the complete compaction curves under the heavy compactive effor,the middle compactive effort and the light compactive effort through amount of indoor compaction test. Using the four parameters equation for fine-grained soils putted forward by Hua Li (2001), the purpose of this study is on the applicability of the equation for the complete compaction curves established by the dropping hammer test. The variation law and inner influencing factors of the parameters after the test date fitting was analyzed; the complete compaction curves was predicted under the heavy compactive effort and the light compactive effort based on the compaction test under middle heavy effort, and the relation between parameter and soil properties,compactive effort was discussed. The result showed that that the four parameters equation can well fitting the compaction curves established by dropping hammer test, meanwhile the compaction curves for the soil under which under different compactive effort can also be predicted. Based on the improved unconfined compression strength test and the direct shear strength test, the strength characteristic of the compacted soil was studied. The failure forms and the unconfined compression strength variation laws varied with water content during the improved unconfined compression test were concluded, meanwhile the relation between compression strength and compactive effort was analyzed; The variation laws of cohesive force and friction angle vary with water content were obtained and its inner cause was analyzed. The California Bearing Ratio(CBR)is also a kind of partial shear strength value as well. The variation laws of CBR value after saturation which based on the saturated CBR and unsaturated CBR test near the optimum water content was studied. To guide the engineering practice, the variation laws of the CBR value varied with water content and the unsaturated CBR and saturated CBR were revealed according to the saturated CBR and unsaturated CBR test near the optimum water content.