Research On Settlement Control Technology Of Bridge-approaching Section Of Expressway Under Fast-Track Construction Condition

At present, by the increasing of our national economy, expressway is more and more important to national economy. More and more expressways are needed for transportation imminently. So the decision makers of managerial department hope the time limit for an expressway project is as short as possible. Then the expressway under fast-track construction condition has a problem which is settlement control of bridge-approaching section. This will induce severe bumping at bridge-approaching. This dissertation founds settlement control technology of bridge-approaching section of expressway under fast-track construction condition for practice.There are two problems to solve bumping at bridge-approaching. One is the index and criterion of settlement control of bridge-approaching section, the other is settlement control technology of bridge-approaching. This dissertation puts forward "maximal difference of vertical slope" as index of settlement control of bridge-approaching section based on performance in service of pavement and gives the criterion of maximal difference of vertical slope based on subjective evaluation. Basis for decision-making of settlement control is put forward by calculation of technical requirements, construction period and economy.Settlement control technique under fast-track construction includes foundation disposal and presetting-height. By the calculation of technique and economy, some techniques are selected for fast-track construction condition: vacuum preloading, composite foundation and EPS embankment. This dissertation analyzes mechanism of vacuum preloading and gives its technique of design and construction. By the time and space distribution of settlement of bridge-approaching, combining the index of settlement control, this dissertation puts forward the criterion and design design method of presetting-height of bridge-approaching section of expressway, and gives the method of cross slope adjusting and three typical presetting-height mode.The reasonableness and feasibility of this technology is demonstrated by the example of Jiading-Jinshan expressway project in Shanghai.