Study On Damage Features Of The Rock Mass In The Sliding Belt Of The Giant Landslide Under The Strong Earthquake

Wenchuan earthquake induced Daguangbao landslide, because of its features, such asthe huge scale, intense destruction, unique signs of deformation and its complex formationmechanism and so on, which drew seismic and geological workers’ and enthusiasts’attention all over the country and even the world.This paper takes the Daguangbao landslide as an example, which is interested inwhich kind of rock the nature of the sliding belt is controlled by? How does the frictionof the sliding belt drop sharply? What are the causes of damage and fragmentation ofrock masses in the sliding belt? In order to solve the above problems, the author enteredthe Daguangbao base many times, on the basis of the verification of regional engineeringgeological conditions, has made the outdoor explorations and tests, like the grain sieving,taking the core sample in drilling hole, the drilling TV, the sound wave test as well as theelectron microscope scanning and physics mechanical properties experiment in the roomand so on, has done the more thorough analysis and researches to damage features ofrock masses in the sliding belt and the sliding bed, in addition to the physical simulationexperiment in the door, the process of rock masses damage reappeared visually andvividly under earthquake. Through the theory and the experiment, made analysis andexplanation to damage mechanism, the rock masses fragmentation and friction drop insliding belt about the Daguangbao landslide to a certain extent. This paper study obtainsthe main conclusion are as follows:(1) Wenchuan earthquake with large magnitude, high intensity, long ground rupture,long-duration time, shallow focal depth features and wide influence, is caused by thediastrophism of the central fault and front-range fault together in the Longmenshantectonic belt, it is an earthquake dominated by thrust, with a small amount of dextral strike-slip component, which caused a significant landslide and collapse earthquakedamages. Daguangbao landslide which has intense high-speed and long-distancemovement characteristic, has long and large sliding face, and whose landslide dammingdam is highest in the world, and formation mechanism is complex and unique, is a hugelandslide triggered by earthquake.(2) Rock masses in the sliding belt of Daguangbao landslide has complexcombination, high degree weathering, the jointing growth and bad integrality specialcombination features. The nature of rock masses in the sliding belt is mainly controlledby structural features of jointing growth dolomite. From the extent of damage, the depthof damage and the thin-microscopic features of damage to carry on the analysis to therock mass damage features in sliding belt. The exploration and test results supplementand verify mutually, the analysis on damage features is reliable. On basis of thethin-microscopic features of the rock mass damage and fracture surface, the rock massdamage-fracture form can be summarized as the shearing failure (pull and shear function)and the wing cracks extend failure, have been separately made the explanation tophysical mechanics features of rock masses damage and fracture. After rock masses inthe sliding belt fractured, the shearing strength parameter and the complete index of therock mass both dropped, reduced the rock mass quality, and rubbing, rolling and thethermal reaction function of sliding body in the movement made the friction of thesliding belt drop.(3) Damage and fracture of the rock mass in the sliding belt is the result of acombination the internal and external factors, the formation lithology and the rock massstructural feature the sliding belt locates is its main internal factors, while the earthquakeload is the key external factor, which is the blasting fuse and the principal offenderinduced the landslide and caused the rock mass in the sliding belt to damage and fracture.(4) Damage and fracture of the rock mass is the process of inherent drawbackschanging dynamically and progressively under the earthquake load.(5) the physical simulation experiment on shaking table was designed andimplemented in the door reappears the washing mop effect visually and vividly,which gives realistic and powerful supports to analyze the action mechanism.