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通过对青藏铁路清水河地区拼装式涵洞地基温度和沉降的观测,研究多年冻土区拼装式涵洞现浇混凝土基础对冻土的热扰动影响、地基的回冻规律和冻土人为上限的变化特征,分析涵洞结构随地基冻胀、融沉产生的变形。经过2个冻融周期的现场测试和研究表明:青藏高原清水河细颗粒高温多年冻土区涵洞基础施工的时间若选在10月下旬,明挖基坑及现浇基础混凝土对基底以下多年冻土的影响深度为1.1~1.3 m,施工扰动、融化后的冻土地基回冻时间为45~50 d,涵洞基础施工2年后多年冻土地基人为上限上升了1.0 m左右,冻土上限沿涵洞中轴线在其中部上升大,两端上升较小,这说明涵洞路基和涵洞具有保温隔热的作用;涵洞建成1年后地基沉降大部分已发生,且2年中涵洞地基的不均匀沉降基本稳定。
Through the observation of the temperature and settlement of the confined culvert foundation in the Qingshuihe area of the Qinghai-Tibet Railway, the influence of the cast-in-place concrete foundation of permafrost on the thermal disturbance of permafrost, the law of frozen backfill and the change of artificial upper limit of frozen soil , Analysis of the culvert structure with the foundation frost heave, thaw sinking deformation. After two freeze-thaw cycles on-site tests and studies have shown that: Qingshuihe fine Qinghai-Tibet Plateau culvert permafrost foundation construction time selected in late October, open-cut foundation pit and cast-in-situ concrete below the base of the perennial The depth of influence of soil is 1.1 ~ 1.3 m. After construction disturbance, the thawing time of thawed frozen soil foundation is 45 ~ 50 d. After 2 years of culvert foundation construction, the per capita upper limit of permafrost soil rises by about 1.0 m. The upper limit of permafrost The central axis of the culvert rises in the middle of the culvert and rises slightly at both ends, which shows that the culverts and culverts have thermal insulation effect. Most of the foundation subsidence occurred after one year of culvert construction and the uneven settlement of the culvert foundation in two years Basically stable.