Testing Research On Classifying Of Expansive Soil Used As Embankment Filler And It's Control Indexes In Construction

Expansive soil is a natural geological body with lots of fissuring and distinguishable swelling-shrinkage characteristics. It's nonideal embankment filler totally said. But using expansive soil as embankment filler has to be considered in the area where there is lots of expansive soil on the highway route, accounting of many factors such as economy and circumstance. Therefore, to classify the expansive filler quickly and truly to confirm the corresponding treating measure for embankment and to control the construction of expansive soil embankment effectively are important problems that must be solved.On the base of analysis of advantage and disvantage as well as the relativity of the indexes in existence, the new classifying method of expansive soil used as embankment filler is put forward. In addition, the effect of compactive efforts and moisture content to the CBR and resilient modulus are analyzed through testing, Applicable indexes for the control of expansive soil embankment in construction are put forward.The characteristic of expansive soils in four representative south and north areas are researched. The following results are discovered .The standard moisture absorption water content reflects the expansive characteristic of expansive soil essentially; Total rate of swelling-shrinkage could be substitute by 50KPa expansive rate approximately, 50KPa expansive rate presents linearity relativity with CBR expansive rate. Based on these results ,the method which uses CBR expansive rate,the standard moisture absorption water content and plastic index as classifying indexes to classify expansive filler is put forward .Compaction tests, CBR tests, resilient modulus tests on three representative expansive soils are carried out under the condition of different compactive efforts and moisture content. The results have shown that the moisture content being corresponding with the biggest CBR is more than the optimum, and is very close to its natural moisture content . The CBR and resilience modulus of expansive soils are the biggest if embankment is compacted under the natural consistency and big compactive effort is used, water stability under this condition is also the best. Based on these results , consistency,dry density and CBR for are put forward to control expansive soil embankment in construction.