Analysis Of The Behavior Of Sandstone Compaction Pile And Field Test On The Foundation Of A Large Oil Tank

In this paper, based on the engineering practice and field test on the composite foundation with sandstone columns beneath a large oil tank constructed by SINOPEC Maoming Petrochemical Company, the explicit analyses of settlement and bearing capacity for this kind of composite foundation were studied, and the method for estimating the distance of sandstone compaction piles was theoretically investigated. At the same time the behaviors of soil closed to the piles during piling was studied.Through reviewing the previous researches on the theory of estimating the distance of sandstone compaction piles, a new method taking account of both lateral and vertical compaction effects happened blow the piles as well as the effect of the fine-grained content was proposed. The new method correlates the calculation of distance with SPT blow-counts to facilitate its use in engineering practice.Analytical solution was obtained for the stress and displacement field induced by expansion of cylindrical cavity based on the soil plastic mechanics and related theory. The effects of corresponding parameters on plastic zone as well as the stress and strain of soil were discussed. The solution is then applied to investigate the effects of compaction and the bearing capacity of such pile.At last, the explicit analysis of the experimental data obtained during the construction and loading test of the oil tank was presented. Currently, it is the largest oil tank in China. The deformation of the foundation was analyzed. The pile-soil stress ratio and the pore pressure in substratum were obtained during loading. The result shows that the foundation improved by sandstone compaction piles is very successful and the behavior of the substratum is very important to the foundation.