GRANITE SPHERICAL WEATHERING FEATURES AND RELATED ENGINEERING GEOLOGICAL PROBLEMS IN THE SOUTHEAST AREA OF FUJIAN PROVINCE

Granite is widely distributed in the southeast area of Fujian Province.Granite spherical weathering and the relative engineering geological problems are very prominent because of differences of mineral compositions,regional geologic structure and warm-wet climate in this area.Spherically weathered rock blocks of various sizes fall from the top of slope or roll along slope surface.Collapse and landslide occur because of rainfall or excavation near slopes mixed with weathered spherical rock blocks and residual soil.When tunneling in stratum of spherical weathering,concentration of stresses can occur in the primary support of working face.Then,instability of rock and ground subsidence can appear.Latent spherical weathering rock may be identified as bedrock.It is very difficult to drill for pile foundation.Bare spherical weathered rock can threaten the bridge pile and abutment on the steep slope.