THE PROPERTY AND FORMATION MECHANISM OF JINGDU LANDSLIDE GROUP IN SHENZHEN CITY

JingDu landslide group,which consists of landslide HP1and landslide HP2,occurred in the hilly areas of low mountain front.The rhyolitic tuff and its weathered material are revealed mainly around the landslide field.Landslide HP1,as an existing landslide,slid again.At the same time,landslide HP2 was triggered by HP1.It is found that the sliding body is mostly composed of gravel soil and silty clay mixed with mass rock,the soil of sliding zone is mostly composed of plastic brown-yellow and brown-red cohesive clay,and the sliding bed is composed of completely decomposed thyolitic tuff.The property and mechanism of formation are also demonstrated for the JingDu landslide group through analyzing the characteristic of deformation and the engineering geology condition.Moreover,the effect of rainfall upon landslide is discussed.It is concluded that the excavation at the foot of the slope,which resulted in the failure of the brace on the foot of the slope,resulted in the development of the landslide group.The continuous and excessive rainfall is only the inducing factors.The occurrence of the deep-seated slide doesnt correlate necessarily with rainfall.However the continuous rainfall can reduce the dynamic stability of the deep-seated landslide and promotes the occurring of sliding.The weathered tuff,which distributed widely in Shenzhen area,can develop into sliding-prone stratum under the suitable hydrogeology condition.