Numerical Analysis On Differential Settlement Of Roadbed Broaden In Reconstruction Project Of First-class Highway

In recent years, many cities successively carry out reconstruction and extension oforiginal highway in order to increase the efficiency of regional transport. As the newand old roadbed consolidation degree is different, so the settlement of new subgrade isgreater than the old, this is the differential settlement. Differential settlement will lead topavement structure damage, serious will result in the instability of the subgrade.Reducing the differential settlement is a main technical problem in reconstruction andextension of highway. Combined with a first grade highway reconstruction project, thispaper uses the numerical method to analyse the controlling measures of differentialsettlement and the main content is summarized as follows:(1) the application of numerical calculation method in soil consolidation settlementof the problem.Using the finite element analysis method based on Biot consolidation theory tocalculate a consolidation problem, then compared with the result of using Terzaghiconsolidation theory to indicate that the numerical method is reliable.(2) The characteristics of widening subgrade differential settlementOn the basis of summarizing the domestic and international highwayreconstruction project practice, analyzes the diseases and cause of differential settlement.Through a analysis software to simulate the settlement deformation, stress distributionand pore pressure change of reconstruction project. According to the flexural tensilestrength of pavement structure layers, the control index of differential settlement isascertained by numerical theory.(3) Analysis of differential settlement controlling measures in a reconstructionproject of first grade highway.Combined with the widen way and geological conditions of BengGu first gradehighway reconstruction project, selecting the typical roadbed widening section andnumercal theory to analyse respectively the influence of widening way, slop ratio, stepsize, set of geogrid, finally puts forward some conclusions.The conclusion of the paper can be taken as reference for the similar project andengineering design.