Analysis Of Ground Settlement Due To Tunnel Construction With Shield In Soft Soil

In soft soil, while applying shield tunnel technology in city subway constructions, it may cause subsidence upward the tunnel in the process of shield driven. In the phase of tunneling construction and application, tunnel settlement would be generated. It affects buildings around and normally application of substructures directly. How to reduce the disturbance degree in soils around by construction and study the distinction of subsidence and analyse the reason of subsidence is an important matter in shield method construction. It has practical project significance.Based on the instance of Guangzhou Metro Line No.4, this paper analyses the subsidence that caused by shield method construction in two ways. One way is that the fundamental of nonlinear finite element was used and large software of nonlinear finite element that called ADINA was applied in building 3-D model of the process of shield method construction in soft soil stratum. Then the curve of subsidence that caused by shield method construction was calculated and the distinction of vertical subsidence was analysed . The second way is that the fundamental of image method which advanced by Sagaseta and the formula which deduced by Jiangqiliang etc for calculating the shifting of soil were used. A program was work out for calculating the regularity of subsidence after the impelling of shield. Subsidence that caused by shield construction in soft soil was estimated. It could be induced from the outcome of analysis that the most important reason of subsidence was stratum loss in the process of shield method construction. Subsidence could be forecasted accurately only with consideration of the construction process and soil conditions in different areas. The result that calculated in two ways was in correspondence. The maximum subsidence value was 90mm more or less. It can be induced from the analysis that the result of the two ways is in correspondence. The maximum subsidence value were both 90mm more or less. The cross hydroseparator curve of subsidence that caused by the disturbance of soil was in accordance with normal distribution curve that induced by Attewell,Woodman separately.