多年冻土区桥梁工程钻孔灌注桩温度场研究

Study on ground temperature of cast-in-place pile of bridge in permafrost regions

针对多年冻土区钻孔灌注桩施工中混凝土水化热对冻土温度扰动问题,以青藏公路214沿线查拉坪旱桥桩基为实例,结合桩基施工完成后现场地温观测数据,进行了钻孔灌注桩水化热对桩周土体温度的影响研究,并分析桩周土回冻过程中地温场的变化规律.结果表明:混凝土水化热对距桩0.6 m与0.9 m处冻土温度影响较大.距桩2 m的测温孔温度曲线受混凝土水化热的影响较小,可以忽略.桩基施工完成后33天后桩侧开始出现负温,119天后桩侧各土层均降至负温,134天后桩侧土形成稳定冻土,201天后桩侧各土层温度与天然孔较接近.

Based on the temperature field observation of permafrost around the cast-in-place pile foundation of Chalaping bridge along the Qinghai-Tibet Highway 214,the thermal effects of cast-in-place pile hydration heat are studied and the variation laws of temperature field during refreezing process are analyzed. Results showthat：（ 1） Hydration heat significantly influences the temperature of CA15 and CA14,while slightly disturbs the CA17 with a distance of 2 m to pile.（ 2） It took 33 days after pile construction,when the negative temperature can be seen on the pile skin. 119 days after construction,the temperature of all pile skin dropped to negative. It took134 days after construction to refreeze the soil around the pile and 201 days to decrease the pile temperature to natural temperature.