INVESTIGATION ON CATASTROPHIC LANDSLIDE OF JULY 11, 2015 AT TAIPINGSHAN,SHAOXING COUNTY,ZHEJIANG PROVINCE

On July 11, 2015, by the early continuous rainfall and short-term heavy rainfall caused by the Chan Hung Typhoon, a large landslide occurred on the basis of first sliding during the year of 2000 in Shaoxing county, Zhejiang Province. The front of landslide swelled significantly and the landslide boundary expanded rapidly. Life and property safety of about 25 households in front of the landslide were threatened. The crack, surface displacements and deep horizontal displacements monitoring were examined in this paper. Such examinations were combined with site geological investigation, site engineering geological survey, site moisture content test and permeability test. The characteristics of the landslide and the formation and failure mode of the landslide by preliminary understanding were analyzed. The results show that:(1) the plane form of the landslide was shaped like a chair and the main slide direction was about 140nd the plagioclase was about 330meters long and the front and trailing edge were 150~180 meters and 75~105 meters wide, respectively, and the volume was 105104m3 and the landslide was made of eluvial and alluvial silty clay with gravel; (2) heavy rainfall is the major factor in inducing the sliding deformation; (3) the landslide is substantially in state of creep deformation and slides slowly and will remain steady state within the general period, which can be determined for the tractive landslide.