| The Neogene hard soil-soft rock are one of the common types of landslides in Northwest China.There are 73 large and medium-sized hard soil-soft rock landslides in the slope belt along the northern bank of the Weihe River in Baoji City,Shaanxi Province.The Caijiapo landslide has the highest activity intensity and risk.some sets of centrifuge model tests were conducted to simulate the deformation process via detailed geological investigation and comprehensive research on hard soil-soft rock strcutre mechanics,stability analysis of landslides.Some new breakthroughs have been achieved as follows.1.This paper preliminarily determined that hydraulic humidification and pore water pressure increase are the inducing factors for the initiation of landslide slip.The Caijiapo landslide is located in the slope belt of the loess plateau,which is not only the steep geomorphological zone crossed by the fault on the northern margin of the Weihe River,but also the transition zone between the two hydrological units of the loess plateau and the bottom of the Weihe valley.It also accelerates the regional hydraulic exchange.These factors lead to extremely abundant groundwater exposure in the landslide area,and the coupling of water and soil is the main controlling factor for the deformation of the Caijiapo landslide.2.Investigation and testing have obtained the geometric distribution characteristics of Caijiapo's deep sliding zoneThe Caijiapo landslide is an old rotational-translationtal landslide.The boundary shape of the landslide body is clear.The clay content of the sliding body is between 30% and 45%.The mineral composition is dominated by the illite mixed layer,and the content is between 19.0%and 29.8%.between.The front edge of the landslide exposes a nearly horizontal sliding zone with a thickness ranging from about 0.8-2m.The maximum content of clay particles in the sliding zone is 50.36%,and the hard soil and soft rock have the characteristics of strain softening.Because there is a stress difference of about 25% between the peak strength and the residual strength.Stability calculations show that the landslide is currently in an under-stable stage.3.Simulation and analysis of the deformation and slip process of the Caijiapo landslide under the conditions of humidification and rainfall-increased pore pressureThe soil-soft rock landslide is extended and deformed by traction from the front edge to the rear edge.The deformation of the sliding zone causes the destruction of the entire slope.The sliding process includes plastic extrusion of the bottom sliding belt,horizontal sliding of the front edge sliding body,and sliding of the trailing edge sliding body.When the slope faces heavy rainfall,unloading fissures will be generated in the steeply changing area of the slope shoulder,and rainwater will spread down along the fissures,which will induce shallow deformation of the slope surface.4.This paper discuss the movement mechanism of Caijiapo landslide,which provides a reference for the engineering and technical treatment of the landslideThe soil-soft rock landslide has two sliding modes: deep and shallow sliding.In the process of engineering treatment,for deep landslide activities in hard soil and soft rock,drainage tunnels need to be set through the sliding zone;for shallow rainfall deformation,it is necessary to cut the slope and reduce the slope of the slope. |
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