利用热管-保温板复合结构提高冻土区路基稳定性研究

Study of Using Thermosyphon-Insulated Board to Enhance the Stability of Permafrost Embankment

热管-保温板复合路基是青藏铁路应用广泛的一种新型路基结构形式。通过数学模型分析,推导出用于青藏铁路冻土路基热管的热流表达式,并用热焓法考虑冻土相变问题对该路基结构形式及无保温板情况施工后20年的路基温度场进行数值模拟。通过数值模拟可知：保温板能够有效地阻止热量由路基面向下传入地基中,使0℃等温线始终在保温板底层;复合路基多年冻土上限的位置要比无保温板时的高;该结构形式对路基中心、路肩和坡脚下的多年冻土上限抬升的综合效果更好;考虑施工条件后,复合路基在保温板铺设距离天然地面之上0.3~0.6 m对于路基稳定性最为有利;该路基结构形式为青藏铁路多年冻土区路基的理想结构形式,有利于克服全球变暖的影响。

Thermosyphon-Insulated Board Permafrost Embankment is a widely-used embankment formation on the Qinghai-Tibet railway. By analysis of mathematical model, this paper deduced the formula to express the heat flux of thermosyphons in permafrost foundation, and simulated the construction formation of both condi- tions of with and without insulated boards, considering the phase change of permafrost with the method of enthalpy after the construction up to 20 years. Simulation results verify that insulated board can effectively protect the heat from transferring into the foundations, and the frozen table is always around the lower bottom of the boards; the position of the frozen table with insulated boards is higher than that of without; the embank- ment formation has a better effect on the center of embankment, the shoulder and toe of the roads than others; after consideration of the construction effect, the best lay out of the insulated boards is higher than the position of natural ground surface to 0.3-0.6 m; this formation of the embankments is the right effective constructer to be used in the permafrost on the Qinghai-Tibet railway. It will conquer the influence of the global warm.