Triaxial Compression Tests on Unsaturated Kanto Loam for Calculation of Bearing Capacity of Supporting Ground

Abstract

Many crane overturning accidents are caused by the failure of the ground where the crane is placed. When considering the stability of such cranes, there is little information on the strength and deformation characteristics of Kanto loam, which is generally in an unsaturated condition. The authors conducted unconfined compression test and unsaturated triaxial compression tests under the same conditions using specimens made of Kanto loam to examine the results of bearing capacity tests on a model ground. As a result, the ultimate bearing capacity calculated using the unconfined compression strength was underestimated by about half of the bearing capacity test results. On the other hand, the ultimate bearing capacity obtained by using the strength parameters from the unsaturated triaxial compression test was estimated to be 20% smaller than the experimental bearing capacity, but the influence of the bearing width could be estimated. Also, the analytical and experimental values of the ultimate bearing capacity were almost equal in the range where the deformation modulus was similar between the bearing capacity test and the unsaturated triaxial compression test, suggesting that the influence of the increase in foundation width extends in the direction of the ground depth. In addition, it was reported that the choice of Poisson’s ratio has a significant influence on the prediction of settlement, which determines the stability of the machine.