Researches Into The Design Approach And Technical Parameters Of Approach-Slabs

Providing approach slabs on the road-bridge transitional segments for buffer and transition is one of the key measures for stopping and alleviating bump at bridgehead. This Study makes a systematic study of the design approach and technical parameters of approach-slabs based upon collection and retrieval of the existing findings and by way of combining theoretical analysis with actual application.This Study sets the calculation models of dynamic response on the transitional segments with and without slabs on the basis of the chart of actual bump in the segments, and studies the controlling criteria of differential settlement of road/bridge with and without slabs pursuant to the impact to driving comfortableness and to safety.The strengthened length of subgrade ground of the transitional segments is estimated in the Study by dynamic analysis of vehicles on the segments, model simplification and calculations/analysis.The Study sets the design reference values of length of such slabs by means of stress analysis of vehicles running on the segments, longitudinal grade changes of pavement incurred from road sinking, length of batter damaged by soil, lengths of preserved openings for bridge approach before being filled, and analysis of both approach-embankment hight and subgrade settlement. Meanwhile, the dip angle (the included angle with pavement) value, which well conforms with actual conditions, of oblique slab, is figured out by theoretical analysis of rigidity-to-flexibility transition from road to bridge and vice versa.The reinforcement parameters of slabs for highways of different classes are designed through analysis of slab stress models as well as computerized simulative analysis. In combination of the existing theoretical analysis, foreign experience and real applications, the thickness of such slabs is proposed.The Study presents reliable data, full and accurate contents thus the results therein may be spred and applied.