青藏铁路冻土区混凝土灌注桩施工对基础承载安全性影响研究

Study on the Safety of Load Bearing Influenced by the Construction of Concrete-priming Pole of the Bridge Foundation

青藏铁路冻土区的桥梁桩基施工大量采用了钻孔灌注桩,在暖季黄金施工季节中,地基土的回冻时间就不能按照规范来确定。如果不能准确分析回冻时间,在后期架梁等施工操作中很可能会因桩基失效而发生重大安全生产事故,给青藏铁路建设带来严重影响。因此,需根据现场的施工条件确定地基土回冻时间,保证施工安全和高效。为此,笔者对混凝土不同入模温度条件下钻孔灌注桩回冻过程进行了深入研究,从理论和实际上确定桩基周围冻土形成承载力的过程和规律,对今后桩基承载的各个阶段的安全性和可靠度在理论和实践中找到科学的结论。研究中应用青藏高原的各种观测数据、施工数据,根据工程传热学理论加以分析,采用ANSYS工程分析软件进行模拟,得出了较为精确的结果,研究的结论为青藏铁路施工修改施工规范、保障施工安全提供了理论上的依据。

The construction of Qinghai-tibet railway brought about many problems to the constructors. This study focused on the problem that the bridge foundations crossing the permafrost might not ensure the safety of the construction. Heat from the operation and the concrete would melt the permafrost and change the characteristics of the ground. Such change might lead to the lack of load bearing capacity of the bridge foundation. If such change was not understood, the risk of accident would occur during the construction. Some methods and tools have been applied to simulate and assess the result of such change. Suggestions also have been given to constructors to modify the technique of the foundation construction and they would guarantee the safety of the construction.