季冻区高速铁路路桥过渡段稳定性试验研究

Experimental Research on the Stability of Embankment-bridge Transition Section of High-speed Railway in Seasonal Frozen Regions

研究目的:对于路桥过渡段较多的高速铁路地段,控制路桥过渡段的沉降差是保证列车运行平顺性的重要因素,尤其是处于深季节冻土区的高速铁路路桥过渡段,其变形控制更加严格。本文以哈齐高铁某路桥过渡段为试验监测断面,基于现场地温、冻胀变形和沉降变形的试验数据,分析寒区高速铁路路桥过渡段的地温、基床表面的冻胀变形和基底的沉降变形,揭示寒区高速铁路路桥过渡段的地温与变形特征,从而评价路桥过渡段的稳定性状况。研究结论:(1)建设初期,采用掺3%水泥的级配碎石作为桥后回填料较粗粒土易吸热和放热;两者在相应深度处的温差随时间的推移逐渐减小并趋于0℃,最终桥后级配碎石与粗粒土达到新的热力平衡;(2)采用掺3%水泥的级配碎石作为路桥过渡段桥后回填材料,其基床表层与桥台间的最大变形差值为4.6 mm,满足规范要求;(3)级配碎石作为桥后回填材料,其基床表层的变形随时空的变化过程分为四个阶段:冻胀快速发展期、冻胀相对稳定期、冻胀抬升期和融化回落期;(4)级配碎石作为桥后回填材料,其冻结深度与基床表层的冻胀变形呈非线性关系,但路堤的最大冻结深度影响其基床表层的最大累积冻胀值;(5)路基阳坡的沉降量较阴坡大,离阴面坡脚越近,基底的沉降量和变形幅度越小;路基施工完成至铺轨前,基底沉降随时间的推移缓慢增大,但目前基底各测点沉降量均满足规范要求;(6)该研究成果可为今后季冻区类似工程设计、施工和维护提供参考。

Research purposes： For the high - speed railway lines with more embankment - bridge transition section, the control of the deformation difference between the road and bridge transition section is an important factor to ensure the smooth operation of the train, especially in deep seasonal frozen regions. In this paper, a transitional section of Harbin - Qiqihar Railway is used as a pilot monitoring section, based on the field test data of ground temperature change, frost deformation and settlement deformation, the ground temperature change, frost deformation of subgrade surface and settlement of subgrade basement of embankment- bridge transition section of high speed railway in cold regions are analyzed, the ground temperature and deformation characteristics are revealed, thus the stability of embankment -bridge transition section can be evaluated.Research conclusions：（ 1 ） At the initial stage of construction, graded crushed stone is easier to be endothermic and exothermic compared to coarse grained soil as for backfill materials of bridge back; the temperature difference in corresponding depth of these two kinds of fillers decreases gradually and tends to 0℃, and finally the new thermodynamic equilibrium is formed. （2） During the freezing process, the maximum deformation of embankment - bridge transition section is 4.6 mm, meeting the requirements of specification. （ 3 ） Graded crushed stone being adopted as backfill materials of bridge back, the change process of frost heave deformation of subgrade surface layer with the temporal and spatial can be divided into four stages： the rapid development period of frost heave, frost heave relatively stable period, frost uplifting stage and thaw felling period. （4） The relationship between frozen depth and frost heave deformation of surface layer of embankment - bridge transition section is nonlinear when graded crushed stone is applied. But, the maximum frozen depth of embankment influences the maximum cumulative frost heaving value of the subgrade surface. （5） The settlement of the southern slope is greater than the northern slope. The closer to the northern slope - toe, the settlement and deformation amplitude of substrate becomes smaller. During the period between completion of subgrade construction and track laying, the settlement of basement increases slowly. Currently, the settlement deformation amount of each measuring points of the basement meets the standard requirements. （6） The research resuhs can further provide reference for engineering design, construction and maintenance in the future.