青藏铁路涵洞现浇混凝土基础水化热的数值分析

考虑相变和热量生成, 导出瞬态温度场问题的热量平衡控制微分方程, 并应用伽辽金法推导出了有限元计算公式. 计算了青藏铁路格尔木至拉萨段DK1258 240处正在修建的涵洞现浇混凝土基础水化热的影响, 结果证明, 现浇混凝土水化热在施工后半年内对涵洞周围的冻土的热状况影响较大, 施工后2 a时仍然还有影响. 为了减小这种影响, 计算了涵洞现浇混凝土基础下铺设厚度为10 cm的保温材料的冻土热状况, 材料分两种方式铺设: 一种铺设与涵洞基础等宽度; 一种铺设比涵洞基础宽度大5 cm. 比较证明: 在涵洞现浇混凝土基础下铺设保温材料可减少现浇混凝土水化热对冻土热状况的影响, 保温材料应按方式二铺设.

Numerical Analysis for the Hydration Heat of Cast-in situ Concrete Foundation of the Culvert on the Qinghai-Tibet Railway

In this paper, taking phase change and heat generation of cast-in-situ concrete into account, the governing differential equations of the problem of temperature field are presented, and the finite element formulae of this problem are obtained from Galerkin s method. From the analyses for the effect of the hydration heat of cast-in situ concrete of culvert foundation at DK1258+240 on the regions of Golmud-Lhasa in the Qinghai-Tibet Railway, it is well known that the effect of the hydration heat of cast-in situ concrete of culvert foundation on the rock or soil surrounding the culvert is very great within half a year, and the effect is still in existence until the second year end. To reduce this effect, in this paper, the temperature fields of the rock or soil surrounding the culvert constructed with insulation material of 10 cm in thickness under the culvert cast-in situ concrete foundation are computed and analyzed. The insulation material is constructed with two types: one is that the width of the insulation material is equal to that of the culvert foundation, and the other is that the width of the insulation material is 5 cm more than that of the culvert foundation. From a comparison, it is revealed that the insulation material constructed under the culvert foundation can greatly reduce the effect of the hydration heat of cast-in situ concrete of culvert foundation on the rock or soil surrounding the culvert, and that insulation material should be constructed with the second type.