Abstract: When damming in Tibet region with high altitude and large temperature difference, temperature control and crack prevention are greater challenges. Pipe cooling and surface insulation are common measures for mass concrete temperature control, which are also very effective. It is a kind of technological innovation to flexibly use the existing temperature control and crack prevention technologies to make them play a better role. Taking the dam section on riverbed of a concrete gravity dam in Tibet as an example, the temperature control measures and standards during construction are studied by means of three-dimensional finite element method. The results show that for the concrete gravity dam located at high altitude, lowering the pouring temperature to 12 ℃ can effectively reduce the maximum temperature of concrete and the temperature difference of foundation; increasing the height of cooling zone to 27 m can improve the deformation compatibility of the concrete in dam body; and adopting polystyrene board with a thickness of 5 cm for surface insulation can effectively reduce the surface stress of dam body under construction.

Key words: concrete crack, high altitude, large temperature difference, temperature control and crack prevention, water cooling

摘要： 在高海拔大温差的西藏地区筑坝，温控防裂将面临更大的挑战。水管冷却、表面保温是大体积混凝土温度控制常用措施，也是很有效的方法。在现有温控防裂技术上，对大坝的温控措施进行灵活运用，使其发挥更好的温控效果，不失为一种技术上的创新。鉴于此，以西藏某混凝土重力坝河床坝段为例，借助三维有限单元法研究了该坝施工期的温控措施和标准。结果表明，对位于高海拔地区的混凝土重力坝，将浇筑温度降至12 ℃可有效降低混凝土最高温度、减小基础温差，增大冷却区高度至27 m可提高坝体混凝土变形协调性，采取5 cm厚的聚苯乙烯保温板进行表面保温可有效降低坝体混凝土施工期表面应力。

关键词: 混凝土裂缝, 高海拔, 大温差, 温控防裂, 通水冷却