Rigid-flexible Transition To Solve Theoretical And Applied Research Bump

Theory and application study on the of rigidity gradation to solve vehicle bumping problem at bridge-head(Abstract) Liu Daiquan Supervised by Prof.Zhao Minghua &Reasearch member Wu ShanzhouVehicle bumping at bridge-head is a common quality fault of those finished freeways in our country. Though much work has been done about this at home and abroad, good method hasn't been found yet. With the development of freeway construction in our country, it is urgent to solve this problem theoretically and practically.First, the existing achievements on this problem are summarized in the paper, combined with the construction reality of our country the reasons lead to the bumping phenomenon are analyzed here and the tolerance settlement value of the embankment at bridge-head that regulated by the current criterion is discussed also. After analyzing the simplified vehicle bumping models built in this paper, the conclusion that the auto load on the connecting part between the abutment is larger than that of embankment can be drawn. Based on the rigidity difference between abutment and embankment and the load difference between the connecting part and embankment, only realizing the rigidity gradation from abutment to embankment in the connecting part can solve vehicle bumping problem on freeway. Therefore the rigidity gradation theory was studied deeply here: an index for measuring the rigidity property of filling material is put forward and the rigidity gradation range is defined here. According to the theory, the method of using half-rigid pile reinforce the embankment below the corbel of the approach slab which form a composite foundation and realize rigidity gradation, is put forward in this paper and the formula to calculate pile-soil stress ratio in light of Visic curvity expansive theory is also deduced here which can be used in design.The test study of this method was carried out on the YiChang freeway in Hunan province, and results show this method can solve the vehicle bumping problem on freeway well with the advantages of low-cost and convenient implements. The method was popularized on otherfreeways in Hunan province and great social and economic benefit has been achieved.