| dc.description.abstract | The attitude of slaty cleavage of the western Taiwan slate belt is roughly in the strike of northeast-southwest dipping at a high angle to the southeast. It shows that high-angle cleavage is easily creeping downhill under the action of gravity. This includes buckling occurred at a dip-slope and also gradual flexuring deformation at the scarp slopes. When the deformation continues to accumulate, the cleavage dipping angle will change and the rock mass will become fractured and weathered. These may occur landslide disasters during heavy rains. Because the investigation of slate slopes has been carried out in many projects in Taiwan and many investigation reports and data have accumulated, these data can be used for controlling factor analysis, since it has not been discussed in-depth, especially at the analysis of various factors affecting the deformation rate.
This study used many reports and data of slate slopes from the multiyear large-scale investigation plan of the Central Geological Survey of the Department of Economic Affair and from the large-scale landslide investigation plan of the Water and Soil Conservation Bureau of the Council of Agriculture. I corrected deformation monitoring data of each
borehole, core drill logs, and water level monitoring data, etc., and also selected a number of different factors for research. The rock-mass factors used are: degree of fracturing, degree of weathering, slate contain ratio, cleavage dipping angle, etc.. The groundwater factors include: depth of groundwater table, maximum rise of groundwater table, etc. The terrain factors include: the height from borehole to the slope toe, and the slope angle from borehole to the slope toe. The deformation factors include: the deformation rate of the top of bedrock and the slip-rate of the sliding surface. After sorting out the data of various factors, first conduct correlation analysis for each factor and each deformation factor, and select the factors with high correlation as the control factor. Finally, a multivariate regression method is used to establish a susceptibility model for slate gravity deformation, which can be used to estimate the gravity deformation rate of Taiwan′s slate slopes.
The results show that factors of rock fracturing, weathering and slope angle are moderately and positively correlated with the deformation rate of the top of bedrock. There is a moderately positive correlation between the variance of cleavage dipping angle and the deformation rate of top of bedrock. If the deformation mass has developed a sliding surface, the groundwater factors, including the maximum groundwater level rise, and the height between the groundwater level and the sliding surface, is highly and positively correlated with the displacement rate of the sliding surface. | en_US |