Study On Control Technology Of Width At Half Fullsubgrade Differential Settlement

Currently,with the development of extension project in our country highway, including the addition of interchanges to improve traffic diversion、old widening project number of lanes increase on to ease traffic congestion. For subgrade widening often need half filling construction, but the more common problem is prone to differential settlement between the new and old roadbed. Settlement difference between new and old subgrade often make the pavement distress, there are some hidden dangers on the running safety of vehicles, but also reduces road service level and traffic capacity. Highway subgrade widening expansion project should not only consider the new and old subgrade differential settlement,but also to ensure that combination of stability and treatment measures. Therefore, the difference of expressway extension project of new and old subgrade settlement of cohesion andcontrol technology research has important significance. Thesis conducted main work as follows:(1)Broaden the premise of expansion in the investigation of the domestic and foreign highway, thesis analyzes the mechanism of widening subgrade differential settlement. The main analysis of the embankment settlement mechanism、new and old subgrade settlement of a difference causes and characteristics of settlement. On this basis, summed up the highway expansion calculation method of the original subgrade subgrade settlement and differences between the old and new settlement after highway expansion.(2) Through comparing the widening embankment form and width, filling height and filler severe in four aspects, respectively, analysis of the change regularity of the settlement, horizontal displacement and that is the most important affecting factor of difference the old and new settlement of roadbed filling height. Based on the above analysis the half range from the old roadbed widening embankment construction gives some proposals.(3) Elaborate stitching generated at the new and old subgrade diseases causes analysis half width fill subgrade different splicing ways and the excavation step size from the old subgrade choice 、soft foundation widening of CFG pile composite foundationin two aspects of new and old roadbed cohesion treatment technology,that can effectively control the differential settlement between new and old roadbed and the slope stability. Through the above analysis of binary image when meet new and old roadbed fill roadbed cohesion proposed several construction treatment measures.