A thesis submitted in the partial fulfilment of the requirement for the degree of Master of Engineering, School of Engineering and Technology

Thesis (M.Eng.) - Asian Institute of Technology, 1980

A comprehensive program of in-situ and laboratory testing was carried out in the soft and stiff Bangkok clay at AIT Campus to evaluate the performance of a new model of a lateral load tester (LLT) or pressuremeter which has been developed by the OYO Corporation, Japan. Three different methods of advancing the borehole were tried out, and their influence on the pressuremeter curve (pressure vs radius) assessed. These methods ·are designated as (1) the hand augering method, (2) the thin-walled tube method, and (3) the wash boring method. Soil parameters which could be identified from the pressuremeter curve were: the total horizontal stress, the pressuremeter modulus, the yield pressure and the limit pressure. The thin-walled tube method yielded the least disturbance to the borehole wall. This could be seen from the values of the horizontal total stress, the pressuremeter modulus and the yield pressure which proved to be quite sensitive to the technique of cavity preparation. On the other hand, the limit pressure turned out to be less 'affected by the method applied. The undrained shear strength could be derived from the pressuremeter curve either by Palmer's graphical method or by Gibson's method. When compared with strengths obtained from field vane shear tests or from laboratory unconfined compression and unconsolidated undrained tests, the values obtained from the LLT tests were about 3 to 3.5 times higher. Good agreement was obtained between K0 values derived from the LLT-curve and those measured previously in the laboratory and by the hydraulic fracturing method in the soft Bangkok clay. A good .correlation was also found between the cone resistance from Dutch cone tests and the limit pressure of the LLT-test.