Laboratory and Field Tests on Performance Evaluation of Portable Test Device for Bearing Capacity of Ground
Minoru YAMANAKA, Hirohiko IWAHARA and Norio NAKAYAMA
Abstract:Bearing capacity of ground is important for any kind of construction. There are various kinds of instruments available for bearing capacity measurement. Recently, one portable test device for bearing capacity of ground has been developed and it gives similar results as of the plate load test. The portable test device can measure bearing capacity within a short period of time. But, there is always a concern about the accuracy of the device because load plate diameter of the device is smaller than that of the plate load test. According to the past experimental studies, the authors make it clear that there is a good correlation between the results of the portable test and the plate load test for the ultimate bearing capacity of cohesive soil. However, a similar verification test for the coarse grained soil is still not carried out, and its performance on a weak stratum near to surface of ground has not been examined yet. In this study, firstly the authors discuss the relationship between maximum grain size, compacted density, and ultimate bearing capacity obtained from the portable test device. Next the authors also determine the performance to identify the weak stratum by the portable test device. Then the portable test device and plate load test were carried out on same ground.As a result of this study, it became clear that the portable test device can identify ultimate bearing capacity of gravelly and sandy soil with maximum particle size of 10 mm. Then the portable test can also detect the presence of weak layer on the ground by changing the plate diameter of device. Moreover, the relation between the ultimate bearing capacity of portable test and that of plate load test can be expressed in terms of the linear equation from the results of verification experiment carried out on same ground. Key Words:Ground investigation, Bearing capacity, Plate load test, Particle size, Density of soil