Estimation of internal friction angle for working platform materials by plate load test

This paper reviews the load-settlement behaviour of 499 plate load tests of various diameters undertaken on granular soils and working platform materials to determine the angle of internal friction mobilised by the test. The observed settlement of individual plate load tests at relatively small settlement has been extrapolated to a theoretical failure of the plate at 10% and 15% of the plate's diameter (D). For each test an effective angle of internal shearing resistance was calculated based on the bearing resistance associated with the stress required to cause settlement of 0.10 or 0.15 times the plate diameter. The results are presented along with a discussion on the use of high friction materials in working platforms and shallow foundations. Characteristic values for the effective angle of internal shearing resistance are provided for all working platform materials tested as well as tests undertaken on platform materials comprising crushed brick and concrete. These values are compared to shear box test results on similar materials. Characteristic values of ϕ’ varying from 44° to 46.4° (0.1D) and 45.3° to 47.8° (0.15D) for crushed brick and concrete materials are calculated, which is slightly higher than that determined from tests on Type 1 material.