The Design Of The Zigong Connection Line Of The Chegndu-Zigong-Luzhou Highway And The Treatment Of Soft Soil Subgrade

Currently, the construction of the city is developing so fast. The urban road plays a pivotal role in the economic development of a city, that is the foundation of the city traffic and transportation and the key to future development of a city. With the improvement of the urban planning, the link between urban roads and highways becomes more and more closely.The urban road network and the highway network will be compact.The road which is named city access road is arising.The city access road is the link between the urban and the rural or the urban and the highway. It is usable to make the time shorten to go to the rural or other cities around. However, the city access road has its feature which is distinct with the urban road or highway.The Zigong connection line of the Chengdu-Zigong-Luzhou highway is the road between the Zigong and the highway. The background of this thesis is Zigong connection line of the Chengdu-Zigong-Luzhou highway. The main contents of study of this thesis are listed as follows:(1)The design of the urban road:In general, this design of the Zigong connection line of the Chengdu-Zigong-Luzhou highway is divided into three parts. The first part is transition section of urban and suburban, the second is the city zone and the end is suburban zone. The design is finished which is based on the geological exploration data, the norms and other literature.The design of the urban road includes the design of section, subgrade and surface, retaining walls, slope protection, intersection and the site selection of the bridge and culverts which is based on the characteristic of the city access road.(2)The treatment of the soft foundtion:Within the road routes, the geological conditions include fish ponds, gullies and overflow land. In order to ensure the security of the road, we should deal with the soft foundation which is harmful to the subgrade. The treatment methods should be determined by comparison with technology and economy. The main treatments method are the replacement method, the dynamic consolidation replacement method and the cement fly-ash gravel pile method. If the thickness of the soft foundation is thin, the replacement method should be applied. Else, gravel pile method should be drawn on. The sub gradewhich is bearing capacity post-construction settlement and stability can fulfill the specification by checking.(3)The optimization design of the cement fly-ash gravel pile threatmen method: Otherwise, the amount of control parameters is excessive, the CFG pile composite foundation is used for the thick soft foundation while is difficult to control. In this thesis, the variables are diameter of the pile, spacing of the pile and length of the Pile. The objective function is the cost of the treatment. The constraints are bearing capacity of foundation, post-construction settlement of the subgrade. The optimization procedure is worked out by MATLAB which is named’cfg.m’. The outcome of optimization design satisfies the requirements of design.