Research On Nutrient Content And Soil Microbial Biomass Of Two Types Forest In The Xiao Xing’an Mountains

Debris is the largest number of and the messiest of evidence existing on traffic accident scene. Owing to short impact time the distribution characteristics of debris can reflect the vehicle’s running status at the moment of collision. At present, debris has become the important basis for traffic accident reconstruction.In traffic accident scene debris is divided into single and group debris. Taking vehicle-mounted group debris as research objects, the discrete element method and the simulation software of EDEM are used to analyze the effects of the number, the size, the shape, the height and the speed of debris on distribution characteristics of vehicle-mounted group debris according to the mechanics of granular media theory. Based on experimental design theory the orthogonal test of the five factors is designed to analyze of group debris’s throw distance. The results indicate that the primary and secondary order of the five factors in the influence of group debris’s throw distance respectively is the speed of group debris, the height of group debris, the number of debris, the shape of debris and the size of debris; the height and speed of debris have great significant effect on debris’s throw distance, while the number, size and shape of debris have little effect on debris’s throw distance. With increasing of the number and size of debris, the group debris’s throw distance linearly decreses. With increasing of debris’s height, the group debris’s throw distance linearly increases. The relationship between the group debris’s throw distance and speed is power function increasing relationship. According to the relationship between vehicle-mounted group debris’s throw distance and speed, based on regression analysis theory, the paper respectively gives and verifies the soybean, sand, clay and coal’s empirical mathematic model of debris’s speed and throw distance.Based on similarity theory, with the light truck as research object, the vehicle impact simulation test apparatus is developed. The tests that vehicle collides with fixed barrier or another car are carried out. The effectiveness of the group debris simulation test is verified by the results. The vehicle impact test results indicate that in the test that vehicle collides with fixed barrier, the relationship between the group debris’s throw distance and speed is power function increasing relationship, the relationship between the group debris’s throw distance and height is linear increasing relationship. In two-car impact test, with the speed of debris increasing, the increasing trend of debris’s distribution area decreases first and then increases. The error of debris’s throw distance between simulation test and impact test is not more than 10%, it’s in the range of error, so the simulation test is effective.