Cut Layer Rocky Landslide Development Mechanism in Lesser Khingan Mountain

Abstract

Bei’an to Heihe expressway utilizes the original second-class highway to widen and expand for expressway, restricted by the original location of old road, widen subgrade of some sections locate in tailing edge of the landslides, influenced by the landform, geological condition, climate and anthropogenic factors, are in unstable states, bring great difficulties to widening and expanding implementation. In process of landslide researching, firstly identify the space form of landslide, analyze the formation mechanism of landslide, evaluate the stability condition and the development tendency of landslide, and then determine the prevention and treatment measures. Took the Bei’an to Heihe expressway cut layer rocky landslide as the research object, employed the geological survey, topographic mapping, geological drilling, indoor test, numerical simulation, field monitoring and theoretical analysis methods to carry an integrated study on the development mechanism and damage mode of the landslide. Through systematic study, drew the conclusions that: the rupture surface is located in completely weathered mudstone; during surveying, the landslide is temporarily in steady state, when the water content continues to increase to 34.7 %, the landslide will reach the state of limit equilibrium; atmospheric precipitation, the island permafrost which scattered in the mountain valley melting water, snowmelt water and seasonally frozen soil thawing water provide a continued water source for landslide, surface water and ground water supply the Cretaceous pore water by infiltration and lateral runoff through surface thermal shrinkage cracks and shallow high permeability rock and soil, low permeability mudstone under the loose overburden forms aquiclude, completely weathered mudstone above the aquiclude which is influenced by the Cretaceous pore water to be soften forms rupture surface; due to the permafrost distribution discontinuities and geological conditions difference, the landslide has gradual, low angle, creeping characteristics.