Study On Security Avoidance Distance Of Active Faults

Previous reconstruction efforts after the earthquake showed that selecting the safe building site is the major problems of the reconstruction efforts. Therefore, carefully studying and scientifically, rationally determining the actual impact scope of active faults, giving the safe distance which can be referred in the construction is of great significance.This thesis is rely on the progect " investigation and assessment of earthquake engineering geological of Longmen Shan and adjacent structures (1212010914205)" supported by China Geological Survey. Based on the field investigation and analysis after earthquake, the author selected the three regions where rupture of surface buildings after the earthquake is more typical to study, namely, wide and gentle valleys (the main street of the Xiaoyudong Town as representative), gentle slope region of the slope foot (Bajiao Temple nursing homes of Hongkou Township as representative) and higher ground (Silicon Industry Company of Shuimo Town as representative), establishing the geological model, using the finite element analysis software MIDAS, through numerical simulation, and the following understanding was made:1. through simulating the original geological model of this three geomorphological structure of the wide and gentle valleys, gentle slope toe and high slope, and the phenomenon of surface rupture are consistent with the results of field investigations.2. Through simulation and analysis of results of practical investigation, the minimum building safety avoidance distance of the earthquake fault zone with different site conditions is given.3. Simulating respectively, from the three aspects of cover thickness, dip angle and the combination of of strata to study the rules of their influence to minimum safety avoidance distance of buildings in earthquake fault zone.(1) The smaller the thickness of cover, the greater the value of the maximum principal stress of surface soil unit, the more the soil units in which damage was occurred, the greater the safe avoidance distance of surface buildings.(2) The smaller the fault dip, the smaller the damage degree of surface soil unit, the greater the safe avoidance distance of surface buildings.(3) Because the different combination of strata, the damage degrees of surface building is different, the more complex the combination of strata, the smaller the safe avoidance distance of surface buildings.