The Developing Regularity And Genetic Mechanism Of Seismic Geological Hazards Along Shiting River After Wenchuan Earthquake

After"5.12"Wenchuan earthquake, Shiting river region got more breakout of the earthquake.Along the river sides, Hongbai town,Jinhua town are the hardest breakout. The secondary hazard attacks more distruction of various types of infrastructure. Landslides, collapse,debris flow block Shiting river at once.There is Jinhua town at the left bank of Shiting river, mainly the alpine,mountains landscape. The valley blossoming and cutting seriously. More exposed Triassic sandstone, limestone. There are Yinghua town,Hongbai town at the right bank of Shiting river and has three bifurcation ditch. More exposed Triassic sandstone, limestone, too. The entire river through the piedmont fault and the central fault, and there has many earthquakes in history.The area has a variety of different presentation styles and distribution, through surveying it found a number of typical landslide and collapse. In addition to find conventional soil-landslide and collapse, but investigate the large rock-slide and thrown landslide, the respond of two ways are more strongly. The thrown landslide is a large rock throw and project to the other side of the flat, glide to the other side of the valley and block the river or stream of debris after breaking out the rock anchor. Thrown landslide is more common in this earthquake, as a typical respond.The distribution of earthquake hazard is regularity. Along Shiting river downstream to upstream, the more seriously to the hazard. To the center of fault, attenuate both sides. The right bank of hazard is more than the left bank, the hazard develops along the bifurcation ditch at right bank. Vertically the hazard occrred in the slope shoulder and slope position, the less at the bottom of slope; the more development at the crest of overhead and thin.Seismic geological hazard causes due to many factors, for example, geological background,elevation,slope morphology,topography,rock lithology. Most rocks are Triassic sandstone and sedimentary rocks, but also locat in cutting strongly valley, develop many joints which are parallel to the slope, so there are many collapses. Seismic waves affect by topographic amplification effect propagating, and reflect many times in the mountains. Seismic acceleration by the elevation position is greater than the foot position, so hazard generally occur in the shoulder and the top of the slope. Compare the probability of disaster,it is more convex slope rather than concave slope,than linear slope. It occur many landslide and slump collapse in the layered rock slope, and the scale of layered rock slope is more large than the countertendency layered rock slope; the countertendency layered rock slope is prone to occur topping damage. Shape likes strip pattern. Blocky rock mass compared with other structures stability.According to the investigation, get hazard of geometry and soil-rock physical parameters base on experience, inverse the seismic instantaneous acceleration, comparing the seismic acceleration of the lowest damage, solute the magnification of at 1.2～2.4. For advising and providing stability evaluation parameter scientifically. It has important practical significance for reconstruction.