DESIGN METHOD FOR SUPPORT STRUCTURE OF ROAD TONNEL IN COLD REGION CONSIDERING THE DECRESE IN COST OF CONSTRUCTION

隧道衬砌的设计和施工主要是根据以往的经验。考虑到隧道衬砌的受力特点和寒区防冻法隧道的发展，使隧道结构合理，降低了施工成本。主要研究成果如下：1.新约束曲线的提出：在本研究中，建立了新的支撑约束曲线(即支撑刚度)。为此，隧道被理想化为一个完全圆柱形的薄壳，两端有两个加劲钢环。得到的主要结果如下：(1)本文得到的支架刚度计算结果小于细环理论的计算结果，最大误差为20%。(2)钢环加劲效应可以用有效宽度(0.35~1)L来表示，其中L是两个环之间的长度。2.寒区隧道全长温度的估计：对于寒冷地区公路隧道的隔热设计，有必要估计和/或确定隧道全长的最低(周期性)温度。给出了考虑隧道-地面与风流之间热对流/导热的理论分析的温度估算公式。研究结果表明：(1)计算值与实测值吻合较好。(2)合理确定隧道进口防冻处理的必要长度。

Tunnel lining is designed and constructed mainly based on the past experience. Considering mechanical characteristic to lining and the development of anti-frost method tunnels in cold region lead to a proper structure, and it can reduce the cost of construction. The principal results of this study are summarized as follows :1.Proposal of newly confinement curve : In this study, the newly confinement curve for support (namely stiffness of support) is developed. To this end, the tunnel is idealized as a perfectly cylindrical thin shell with two stiffening steel rings at ends. The mainly results are as follows:(1)The results for the stiffness of support obtained by this study are less than the ones obtained by the thin ring theory; the maximum error is 20 percent.(2)The effect of stiffening steel ring may be presented in terms of an effective width (0.35〜1)L where L is the length between two rings.2.Estimation of temperature overall the length at tunnels in cold region : For heat insulator design at road tunnel in cold region, it is necessary to estimate and/or determine the lowest (periodical) temperatures overall the length at tunnel. An equation for estimating temperature by a theoretical analysis considering heat convection/conduction between the tunnel-ground and the air flow is presented. From this study, the following results are obtained;(1)The calculated values well agree with the observed ones.(2)We can reasonably determine the necessary length of anti-frost treatment from tunnel entrance.