The Laws Of Development And Genetic Mechanism Of Seismic And Geological Disaster In Region Of Mianyuan River In Mianzhu

Landslides and collapse induced by earthquake are common forms of secondary disasters which has caused widely concerned with its enormous power hazards. In mountain areas, landslides, collapse and other disasters induced by earthquake with large quantities and wide range often caused more damage than the earthquake itself.The study area locating in the western part of China has the following characteristics: mountainous terrain, complex landforms, relative uneven altitude difference, and steep terrain. There are complex lithological characters in the region.The geological phenomena are considerable development, which are influenced by faults of central Longmen Mountain and piedmont.In this thesis, using research methods of systems engineering geology, based on detailed understanding of geological and structural environment of the study area and the region, investigation of geological disasters, and analysis of the distribution laws of different types of geological disasters shows that disasters are main small and medium-scale, which concentrate on from 800m to 1200m and distributed in the neighborhood of the faults of central and piedmont, and the further away from the faults, the less density development of disaster. Then the formation mechanism of typical geological disaster is studied. The research indicates that topography, stratum lithology, geological structure and seismic force have a significant impact on landslides and other geological disasters induced by earthquake. The place where the acceleration value of seismic peak is larger has denser landslide and more number of disasters. Thus the earthquake is the most direct and critical factor leading to a large number of geological disasters and is also the exterior factor, while the inner factors are topography, stratum lithology, and geological structure.Based on formation mechanism of distribution laws and the analysis of controlling factors in geological disasters, this paper has studied on the ground motion response of slope soil under the conditions of the different slope morphology, different types of slope, different direction of slope, different highness of slope impacting on earthquake. Under high-intensity earthquake (â…§above), above the Change Point location of concave slope will appear larger deformation, and the inflexion of the slope occurs the maximum shear strain; contrasting reverse tilt with the tilt slope, the former has poor stability; in the seismic force, in the same direction of the slope inclination and seismic wave propagation, the density of geological disasters are becoming more; slope height is less than 100m, the acceleration of moving peak value is about 1.1g peak, topographic amplification effect is not obvious, while in 100 ~ 200m height, the peak value is about from1.5g to 1.7g, topographic amplification effect is obvious. In the earthquake, the different types of rock structure, different topography, different direction of slope, different incident angle of seismic wave, different types of lithology and slope have different seismic response to rock slopes and different grade and slope height have different ground motion response to boulders. Rock structure, cataclastic texture, layered structure and the granular structure are mostly affected by the earthquake, and most easily caused to collapse and landslide; at the same direction of slope orientation and seismic wave propagation, the damage caused by earthquake aggravates; when the incident angle of seismic wave is less than the critical incident angle, a certain point of structural surface occurs with shear failure first, with the crack extension along the structural surface, slope will become instability and be finally failure; Slope height is different, while the terrain amplification was also significantly different. When the slope height is less than 100m, the terrain is not obvious amplification, and 100 ~ 200m height, the terrain amplification is obvious and the acceleration of moving the peak value clearly focused on range from 1.3g to 1.5g. When the height is more than 200m, the acceleration of moving the peak value is above 1.6g; when hard rock alternate with soft one, it is easy to form a soft surface or sliding surface, and if the slope is weak interface slope, it becomes much more easily causing landslide under the condition of earthquake.Then combining AHP with assessment and prediction analysis of geological disasters in the study area, the synthetical evaluation of geological disaster hazard has been studied and has divided into 5 regions, at last preventive measures have been proposed, which have significant using for reference to the construction of the study area.