The Soft Foundation Treatment Of Lin Zi Kou Bridge Junction Engineering In Xiang Yin And The Analysis Of Its Settlement Forecast

There is an extensive distribution of deposit soft soil in the area of Dongting Lake in Hunan province. Soft soil has such features as big compressibility, high moisture capacity and low shear strength. The road foundation on soft soil has large settlement and lasts for longer time to be settled when external loads are added. So it will be dangerous for highway to be built on it. How to ensure the stability of the highway road foundation and accurately foresee the settlement have become two major technical problems for highway engineering on the deposit soft soil in lake area.Taking the Lin Zi Kou bridge junction engineering in Xiang Yin as a practical example, we elaborate basic engineering features and their treating methods and summarize methods of the settlement of calculation and prediction for soft soil road foundation. According to the geological condition in Lin Zi Kou bridge junction engineering in Xiang Yin, a cement spraying pile for reinforcing the foundation is proposed. Comparing the two aspects of technology and economy, we suggest engineering with sand and gravel spraying to fill the road foundation. Besides, the technology of cement spraying pile, its quality control and detection, and the technology of the powder boast fill are also summarized in the thesis.Through settlement site observation of the construction, we analyze the characteristics of the deformation of the settlement, and discuss the factors which affect the settlement. Some conclusions are summed up as follows: The settlement curve is relatively gently and settlement is relatively small within the period of construction when the soft road foundation is treated with powder spraying, while the settlement curve which is not treated with powder spraying changes with large amplitude and will last for long time to be settled down. However, no matter whether or not the foundation is treated, the settlement will gradually slow down when the fill reaches some height. When fill is finished, after 30 days, the foundation will be in stable state and the speed of settlement and the horizontal deformation are both small.Finally, we apply the grey theory to two sections of (K185+620 and K185+890) of the Lin Zi Kou bridge in Xiang Yin. We use models of the equal time path GM (1, 1) and the unequal time path GM(1, 1) to conduct prediction analysis. The forecast results agree well with experimental measures which demonstrate the validity of the models. The finally amount of settlement predicted by GM(1, 1)model is worth to be for reference. The construction time can be shortened and construction cost can also be lower when the GM (1, 1) model is adopt.