Estimating method of shearing resistance parameters of compacted gravelly soils in field by laboratory tests

It is not easy to know shearing resistance parameters c(d) and phi(d) of compacted gravelly soils in field because of difficulty in getting the undisturbed samples for the laboratory test and also in performing the in situ shear test. In order to estimate shearing resistance parameters c(d) and phi(d) Of compacted gravelly soils in held from shear test of compacted soils in laboratory, the author carried out shear tests( phi=150mm, h=100mm) with change of the gradation and the maximum grain size of compacted soils and compared the test results with those of direct shear test in field using a 300mm X 300mm X 180mm shear box. From a series of laboratory tests using Eliminated Gradation Samples (cut off larger particles simply) and Substitute Gradation Samples (replaced larger gravel-particles by smaller gravel-particles of the same weight), it is known that in situ strength parameters c(d) and phi(d) of gravelly soils can be estimated reasonably by laboratory tests with a few kinds of Eliminated Gradation Samples.