含水量对季冻区路基强度及路面结构力学响应的影响

Impact of Moisture Content on Subgrade Strength and Mechanical Response of Pavement Structure in Seasonal Frost Zone

对季冻区路基路面的力学性能进行相关研究。测试不同深度位置处路基土体的含水量,并对路基土体回弹模量的影响因素进行试验分析,探讨了不同路基含水量下的路面结构力学响应情况。结果表明:冻融循环明显降低土体的强度,但到第6次冻融循环后,土体的强度基本趋于平稳;随着含水量的增加,土体强度减小的趋势逐渐变缓,因此,冻融循环作用对较为干燥状态土体的影响是较大的;路表弯沉、半刚性基层层底拉应力和土基顶压应变与路基含水量及轴载呈正相关关系,其中与轴载近似呈线性关系。沥青层层底拉应变远远低于疲劳极限,因此发生疲劳损伤的概率很小;随着轴载的增加,半刚性基层疲劳寿命逐渐减小,趋势逐渐变缓,含水量增加时半刚性基层疲劳寿命有类似的变化规律,因此为降低半刚性基层发生疲劳破坏的概率,需严格控制土基的含水量及行车荷载。

In the paper the mechanical properties of subgrade and pavement in seasonal frozen area are studied. Water content of embankment soils at different depth is measured, and the influence factors of elasticity modulus of embankment soil are tested and analyzed, and the mechanical response of pavement structures under different moisture content of subgrade is discussed. The results show that. the freezing thawing cycles can obviously reduce the soil strength, but after the sixth round the soil strength basically becomes stable, hence free thaw cycles have a significant impact on dry soils） road surface deflection, semi- rigid basement bottom tensile stress and soil foundation top compressive strain are positively related to roadbed water content and axial load, of which there is an approximate linear relation with axial load. At the bottom of the asphalt layer tensile strain is far below the fatigue limit. Therefore, the probability of fatigue damage is very small; with the increase of axial load, semi-rigid base course fatigue life decreases trend gradually becomes slow with increasing the amount of water, semi rigid base course fatigue life by similar changes in the law, hence to reduce fatigue failure probability of semi rigid base, strictly control the subgrade moisture content and traffic load is needed.