EXPERIMENTAL STUDY ON SEISMIC DILATOMETER(SDMT) OF WEATHERING GRANITE PROFILES IN XIAMEN

Weathered granite in Xiamen is a kind of regional special soil. Its mechanical index is usually investigated with in-situ test because of disturbance. The in-situ mechanical properties of the weathered soils are evaluated by seismic dilatometer test of typical weathering granite layer at three sites of Xiamen Metro Line 1. The results show that the weathered soil derived from granite in Xiamen is classified as silty-sandy soil with quasi-overconsolidation characteristics. Its OCR values are generally larger than 1. It belongs to a part drainage type. Mechanical behavior of the weathered soil particularly is sensitive to the degree of weathering. As burial depth increases, the degree of weathering is gradually weakened. This will cause the horizontal stress of soil decreases, while the strength, rigidity and the shear wave velocity of soil increase. Furthermore, the soil classification is transformed from silt to sandy soil, the quasi-overconsolidation characteristics are weakened and the drainage characteristics is translated from the non-drainage type to the drainage type. Therefore, the seismic dilatometer test is especially suitable for weathered granite stratum with the good reliability and wide applicability. The study has direct guidance for the optimization design of the weathered soil foundation in Xiamen.