路基永久变形对水泥混凝土路面的影响分析

采用由室内反复加载三轴试验建立的路基土永久变形预估模型,计算了典型土组路基永久变形的量值。分析表明,随着路基回弹模量的提高,其永久变形也逐渐减小;路基永久变形在空间上呈垂球面形,在模拟计算中,可采用抛物线或正弦曲线进行拟合。将路基永久变形作为初始条件赋予相应节点,建立考虑不均匀支撑条件的路面结构分析模型,并对不同荷位下路面结构的荷载响应和疲劳寿命进行分析。结果表明,路基变形对柔性基层路面荷载应力和疲劳寿命的影响均十分显著,因此柔性基层不适宜用于重交通和特重交通路面中;对于半刚性基层路面,当路基回弹模量达到40 MPa时,路基永久变形对路面荷载应力和疲劳寿命的影响均较弱,因此建议在路面结构设计中可予以忽略。

A Research of Effect Analysis on Subgrade Permanent Deformation on Cement Concrete Pavement

Permanent deformation prediction models for subgrade soil,which are derived from the indoor repeated loading triaxial test,are used to calculate the permanent deformation value of subgrade composed of typical soils.Analysis results indicate that,the permanent deformation of subgrade is decreased with the increasing of resilient modulus of subgrade;the deformed surface of subgrade is similar to the sphere surface in 3D space and the parabola or sinusoid is used reasonably to make fitting during analog calculation.To specify the subgrade permanent deformation as the initial condition with the corresponding node,and to think about building the subgrade structure analysis model under the condition of inhomogeneous support.The stress response and fatigue life of pavement structure are investigated for different loading position.The results demonstrate that the effects of subgrade deformation on load stress and fatigue life of flexible base course are obvious extremely.Therefore,the flexible base course is unsuited for heavy traffic and super-heavy traffic pavements.And for semi-rigid base course,the subgrade permanent deformation has trivial influence on its load stress and fatigue life,especially when resilient modulus of subgrade arriving at 40 MPa.Consequently,it is suggested that the effect of permanent subgrade deformation could be ignored during pavement design.