Studies on Construction Pre-control of a Connection Aisle Between Two Neighbouring Tunnels in Shanghai by Means of 3D FEM,Neural Networks and Fuzzy Logic |
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| Authors: | You-Liang Chen Rafig Azzam Tomas M Fernandez-Steeger Lei Li |
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| Institution: | (1) College of Urban Construction and Environmental Engineering, University of Shanghai for Science and Technology, 516 Jungong Road, 200093 Shanghai, People’s Republic of China;(2) Department of Engineering Geology and Hydrogeology, RWTH Aachen University, Lochnerstr.4-20, 52064 Aachen, Germany |
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| Abstract: | The ground freezing construction technique is one of the most effective and widely applied site construction methods in soft
soil areas, like Shanghai. Some elevation-inclined refrigeration pipes are arranged for the artificial freezing excavation
of the Pudong-side first-storey connection aisle, which is designed to connect two adjacent tunnel lanes of Shanghai East-Fuxing-Road
tunnel project. No advanced research results could be found for computing the temperature field of tunnels and aisles frozen
with inclined refrigeration pipes. Anyhow the computation of the relevant temperature field is of high importance for the
safe and economical excavation of the above-mentioned aisle. In this paper, a method for computing the aisle temperature field
using 3D FEM is given, and the computation accuracy is verified by contrasting the computed and site measured results. The
back propagation neural networks are also applied to the temperature prediction using self-developed Neural Network-Expert
System software, the predicted results are also very satisfactory. The mechanism during freezing and aisle excavation will
be discussed on the basis of 3D FEM simulation. The authors believe that studying the parameter-sensitivity of temperature
field is very important for the optimum selection of parameter values. So, in this paper, the parameter-sensitivity of temperature
field is also discussed. In order to obtain the optimum frozen wall thickness, the relation between the frozen wall thickness
and the initial freezing brine temperature is studied. At the end, an excavation pre-control plan is proposed by means of
fuzzy logic theory for improving the excavation safety. The research result of the current paper is very helpful for projects
that will be excavated by freezing construction technique. |
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| Keywords: | Connection aisle Artificial freezing construction Temperature field Finite element method BP neural networks Fuzzy logic |
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