Rapid Discriminance To Expansive Soil

Discriminating expansive soil is a very important subject to engineering's geological exploration and architectural design in expansive soil area, in the engineering, discriminating expansive soil rapidly for improving the overall efficiency is particularly important, but in terms of the existing discriminant, discriminant which can quickly distinguish expansive soil needs further study, therefore, it is particularly important to acquire and apply a rapid evaluation index which can quickly discriminate expansive soil.Through the analysis of the expansion mechanism and the conductive mechanism of expansive soil, we can find out easily that there's a correlation between the electrical resistivity and expansion characteristics of expansive soil, this provides us a thought:discriminating expansive soil by electrical resistivity method, hereby,we carried out a series of studies.In the research, we identified and classified a large number of undisturbed soil samples in Hefei area, then tested the initial electrical resistivity value po of each undisturbed soil sample, electrical resistivity value po'of each saturated sample, and the initial electrical resistivity value pi of remoulded sample, electrical resistivity value ?1' of saturated remoulded sample, finally we got the following conclusions:(1)Electrical resistivity value ?0' , ?1' of saturated sample can become a evaluation index for discriminating expansive soil, (among them, the ?1' is more suitable than po'as the evaluation index). The evaluation index possessing a high degree of effectiveness,and the test of evaluation index is fast, continuous, economic. (2)For expansive soil in Hefei area, classification to inflation performance can be acquired from testing electrical resistivity of saturated undisturbed samples with ring knife(61.8 mm in diameter, high 20 mm) and saturated remolded sample with ring knife according to the study of the classification standard. (3) If we get the electrical resistivity value ?0' (or ?1' ) of saturated expansive soil sample,we can make use of the relationship between po'(or ?1' )and other basic evaluation index (free expansion rate, liquid limit, plastic index)to acquire them indirectly, to a certain extent,this can avoid the error from man-made factors in test operation, and the electrical resistivity test is more convenient and rapid.