特殊气候条件对多年冻土地区路基的影响

Effect of special weather on road subgrade in permafrost area

为了揭示多年冻土地区路基病害发生的根源,基于青藏高原五道梁、沱沱河和安多等地的气象资料,研究了特殊气候条件对青藏公路路基的影响。从青藏高原年平均气温变化曲线及年降水变化曲线入手,考虑路基周期冻结和融化过程中水分迁移及相变作用,结合SWS-3型连续面波仪的路基强度测试结果,分析了青藏公路纵向裂缝、波浪扭曲变形和不均匀沉陷等典型病害的发生机理。研究发现:青藏高原的低温特征使得路基常年处于冻结和融化的交替状态;雨季集中、固态降水特征致使路侧积水严重;在特殊的气候条件下路基土体的动弹性模量由最初的均匀分布逐渐过渡到不均匀状态;路基两侧的积水及土体的冻融疏松是造成路基强度不均匀分布、产生病害的直接原因。

To discover the damaging mechanism of road subgrade in permafrost area, the effect of special climate condition on the subgrade was studied with the climate datum at the Wudaoliang, Tuotuohe and An＇duo district along the Qinghai-Tibet highway. According to the curve of annual average temperature and precipitation of Qinghai-Tibet plateau, the reasons for the subgrade damage, such as longitude crack, torsion deformation and un-uniform settlement were studied by the law of the moisture transfer and the phase changing of the subgrade during the perildical freezing and thawing, and by the field test results of the SWS-3 continuous surface wave instrument. It is concluded that the low temperature of the plateau leads to the alternating transition of the subgrade between thawing and freezing frequently; the concentration of the wet season and the solid precipitation lead to the moisture aggregation along the subgrade; the special climate condition is crucial for the un-uniform distribution of dynamic elastic module of the soil strength; the bilateral accumulated water along the subgrade and the thawing rarefaction of the soil are the key reasons for the un-uniform distribution of the soil strength, which directly leads to the subgrade damage. 1 tab, 8 figs, 10 refs.