ENGINEERING SPECIALTY AND REINFORCEMENT METHOD FOR MAN-MADE SLOPES IN WEATHERED GRANITIC SOILS

Southern and East southern China have wide distribution of weathered granitic residual soils. Some have depths of more than 100m. Large numbers of railways and roads have induced many man-made slopes in weathered granitic soils in these areas. It is very important to better understand the engineering specialties of the slopes and then provide effective targeting reinforcement methods for the safe construction and normal operation of the railways and roads. This paper is based on the investigation of 44 weathered granitic soil slopes along four express ways in Guangdong and Guangxi provinces. This kind of slopes is classified as dyke separator slope, netlike structure slope, out-dip structure slope, and isolated boulder slope according to the specialty of the special medium, slope body structures, and the effects of discontinues in the slope body. And then the corresponding stability calculation methods and the influencing factors of slope stability are put forward. Three engineering specialties are brought out from the investigation and research. The temporary stability of dyke separator slope, netlike structure slope is good. Unloading during excavation can strongly affect the stability and other characters of the weathered granitic soil slope because of the existing of discontinues in slope bodies. Weathered granitic soil slope, especially the superficial layer, can be easily scoured. The cause of these specialties are brought forward and discussed. According to each style of the weathered granitic soil slopes, the reinforcement methods and some suggestions are advanced considering the specialties of this kind of slopes. According to the better temporary stability, steep excavation with strong reinforcement is suggested in this paper. Step-by-step excavation with local supporting, anti-erosion measures, foot protection and crest coping, and water drainage are emphasized.