Research On Control Criterion Of Subgrade Settlement On Expressway Widening

With the rapid development of economy,the traffic volumes of expressway are rapidly increasing.A considerable number of expressways in service are no longer satisfy the need for both increasing traffic volumes and social progress.Thus more and more highways are pending to be reconstructed or widened.The expressway widening is an important issue starved for solving in highway construction.The domestic and foreign engineering technical personnel have conducted a large number of engineering practice to solve the negative influence of the differential settlement in engineering.Scholars have some value experience in the completed widening engineering,but they have less related theoretical results and no systematic specification.So the researchers need to further research.In this paper,aimed at the subgrade settlement control of the highway expansion,unifies a highway extension project in The Guangxi Zhuang Autonomous Region,many factors which are about the difference new and old roadbed deformation in the highway expansion project are analyzed by using researching the investigate and design data,further reading the geological report,numerical simulation and theoretical analysis and so on.The train research contents include the following:Combined with the construction examples,by study the natural conditions and operating conditions,the design of the test results and expansion of old roadbed,the nature of the new embankment,and other important factors,the current highway subgrade engineering practice the reconstruction and design of main ideas and general law.Research on the basic principle for uneven settlement,compared the current main embankment settlement calculation method,and the settlement of subgrade stress and consolidation of soil to produce the derivation summarized,get in the highway construction and the settlement of subgrade deformation law,and accordingly puts forward to new and old subgrade differential settlement of main influence factors.By using the method of numerical simulation,the numerical analysis model was established,the article studied the deformation characters and influencing factors of the interaction between the new and old embankment,simulated the influence of many factors such as the different ways of widening,the different subgrade widening width,Vehicle load,the different subgrade filling height,the new embankment material parameters,the slope excavation and slope cutting of old road on differential settlement.And it is concluded that changes in these factors under the action of embankment settlement process and operation of 15 years in the conclusion of post-construction settlement and differential settlement.Through the engineering practice,the combination of roadbed settlement theory and numerical analysis methods,get the law of the settlement of subgrade under the effect of different ways of widening,roadbed widening the width,vehicle load,compaction degree,the subgrade height,the slope excavation and slope cutting of old road on differential settlement.And through the numerical analysis results,the reconstruction of existing specifications to supplement and put forward the proposal,get the subgrade settlement control standard.