Translational landslides are widely spread in red layers area in Sichuan Basin. This type of landslide develops in sub-horizontal bedrock composed of sandstone and mudstone

normally with the dip angle of 3 to 5 degrees

10 degrees at most. Based on geo-mechanical model and sliding process analysis

with the application of the principle of energy conservation

we derived the theoretical sliding distance calculation formula of translational landslide. Three groups of physical simulation tests were established. Group test Ⅰ simulated the sliding distance under the water pressure generated under different conditions of widths and different water heads. Then the theoretical formula was tested by comparing the calculated results and group Ⅰ physical simulation test results. By comparison

the overall distribution shape of uplift pressure under the bottom of sliding body was close to rectangle with very few groundwater penetration points along the shear outlet. To verify the theoretical formula

group tests Ⅱ and Ⅲ were established thereafter. Each group of tests fixed the width and water head respectively. Meanwhile the shear outlet of physical model was set to two types totally blocked and totally seeping water. The results of three groups of physical simulation tests verified the reliability and applicability of theoretical formula. Applying the theoretical formula to Shizishan landslide to calculate the sliding distance

and the calculation results showed the good applicability of the method. The research has some guidance and practical value to prevention and mitigation of translational landslides.