A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering. School of Engineering and Technology

Thesis (M.Eng.) - Asian Institute of Technology, 1986

Despite the widespread use of granular piles, present design methods are largely based on empirical data. In this research thesis, the results of full scale load tests on granular piles are presented which provide a basis for more rational design approach, in Bangkok clay. In this study, eleven granular piles were constructed. Each granular pile was 0. 30 meter in diameter, 8. 0 meter in length and the center to center spacing was 2. 0 meters. A total of eleven load tests were performed on treated soil and five load tests were performed on untreated soil. The experimental procedure consisted of measuring, for a given stress range, the settlement of a rigid plate of varying diameters, seated on the surface of untreated clay. This settlement was then compared to the s e ttlement when the clay was reinforced with a fully penetrating granular piles. This enabled a settlement Reduction Factor for a given diameter of rigid plate . The variation of settlement reduction factors with spacing of granular piles in a triangular grid was also studied. The experimental results are compared to the analytical solution presented by BALAAM s. POULOS C 1978) and PRIEBE C 1976). The second aspect of experimental procedure consisted of measuring the stress distribution between the granular pile and the surrounding soil within the equivalent cylindrical unit. The ratio of stress in granular pile to stress in surrounding soil yielded a stress concentration factor, n, for a given diameter of rigid plate. The variation of stress concentration factor with area ratio as well as with applied uniform pressure was studied. The stress concentration factors for granular pile as well as soil were also calculated. The experimental results were compared to the analytical solutions proposed by BARKSDALE and BACHUS C1983l. Based on the results of the full scale load test it is proposed in the case study that the granular piles be used to support the tennis court. It is proposed that the use of granular piles shall serve the basic aims of minimi2ing differential settlement of the tennis court and also achieving financial economy. The result showed that substantial savings upto as much as 50% can be obtained using the granular pile alternative in addition to minimi2ing the risk of differential settlements.