The effect of bedding errors on the accuracy of plate load tests

Abstract

A series of plate load tests were conducted at the experimental farm of the University of Pretoria. The test areas were levelled by means of three surface preparation methods namely, i) a thin layer of plaster of Paris; ii) a thin layer of well-graded sand and iii) by using only hand tools. In addition, a modified plate load test was designed to eliminate the effect of bedding errors that occur during these tests. Telescopic probes were used to measure the relative displacement at two points below the centre of the plate. The main objective of this research project was to first quantify the bedding errors that occur during plate load tests. Secondly, to evaluate the three different surface preparation methods used in plate load tests to achieve a levelled and smooth test surface, and lastly to evaluate the effectiveness of using telescopic probes in routine plate load tests to eliminate the effects of bedding errors. The stiffness values, determined from the vertical displacement of the plate, were compared with the internal stiffness values determined by means of the telescopic probes. All stiffness values were compared with continuous surface wave (CSW) measurements performed on the same material. The test apparatus, methods and results are discussed in this dissertation. To my