## 3 Results
### Results of Numerical Analysis  
Results of the numerical analysis of the model slope shown in Figure 15 are plotted as distribution of the maximum shear strain increment in the slope body in Figure 16. In Figure 16 it was found that the main potential sliding surface formed in the slope body indicated by the maximum shear strain increment developed from the toe of the slope, and extended toward up-slope direction till reaching the area near the road. The location of the sliding surface intersected with the shear zone bounded by the mapped geological structures, and the crest of the sliding surface was close to the shear zone. The location of the sliding surface appeared to be reasonable as the crest located at the location where significant topographic variation of subsidence occurred close to the road, and the toe exited near the river valley and toe of the slope where ground bulge occurred. Another sliding surface developed with crest located up slope of the crest of the main sliding surface can be observed in Figure 16. This higher position potential sliding surface could indicate a local failure, or it could overlap with the main sliding surface to form a large sliding surface. Location of this second sliding surface also conformed well with the topographic variation of the upper slope as the crest located at subsidence area. Some bulging was found near the toe of this local sliding surface.  
Location of the potential sliding surface was compared to the borehole logging and shear zone profile as shown in Figure 17 by plotting the distribution of the maximum shear strain increment as contours. The depth of the shear surface was at about 57 m, and location of the potential sliding surface appeared to consist well with depth of the identified shear zone materials in the borehole loggings and shear zone bounded by the geological structures. In addition, the lower part of the shear zone passed through the upper portion of the shear zone material in borehole LTW05 above the sliding surface, which explained the wide range distribution of the shear zone material in the logging. The crest and toe points of the potential sliding surface were mapped and compared to the mapped landslide scarps from SPOT5 image as shown in Figure 18. The crest points consisted well with the mapped landslide scarps of SPOT5 image with the crest point of main sliding surface located just near the road. This result consisted well with the finding in field investigation, and suggested a possible damage of the road as often being reported by the authority.  
Figure 15: The slope model of profile X-X’, with the ground layers of rock material (slate) and shear zone. Location of the ground water table is also indicated.  
Figure 16: The distribution of the maximum shear strain increment from the numerical model analysis of the proposed slope model with shear zone (state 2). The distribution of the maximum shear strain suggested the location of potential sliding surface, and the location of the shear zone could be observed suggesting larger shear strain developed in the shear zone.  
Figure 17: The distribution of the maximum shear strain increment plotted as contours, and compared to the borehole loggings and shear zone. The potential sliding surface appeared to pass through the shear zone material indicated as black legend for the loggings, and shear zone passed through shear zone material in the upper part of logging.