A DESIGN METHOD OF ROAD TUNNELS IN COLD REGION

点击翻译按钮获取中文摘要

Icicles and side wall ices in tunnels became a problem for transportation and maintenance. Recently a heat insulator for icicle prevention at the lining surface has been developed in the existing tunnels. The purpose of this study is to propose a simplified design procedure for heat insulator.This project is summarized as follows :(l) A simple practical equation for estimating the thickness of heat insulator is presented. The equation is obtained by using a one-dimensional tunnel-ground model and a non-steady periodic thermal analysis. A comparison with other solutions suggests that the proposed equation provide satisfactory accuracy. By using the equation presented, we can reasonably determine the optimum material of heat insulator and its optimum thickness. In addition, the equation is useful for a better understanding for the thermal characteristics of the tunnel-ground system.(2)In order to identify unknown thermal parameters (thermal conductivity and heat capacity in ground) in appearing the proposed equation, the extended Kalman filter in combination with the one-dimensional finite element thermal analysis is used. A comparison of the temperatures calculated from identified parameters with the measured fild data shows that the method is sufficiently accurate for practical purposes.(3)In order to estimate the unknown temperatures at a planning site of road tunnels, Semi-Yariogram is used on the basis of the a stochastic method. A comparison of the estimated temperatures with the measured fild data gives satisfactory results.