降雨条件下路基土体水分入渗损伤破坏研究

Research on the Damage and Failure of Soil Moisture Infiltration in Roadbed under Rainfall Conditions

针对沥青路面产生裂缝后雨水入渗影响到路基土体造成翻浆等病害问题,在粉质黏土路基受水分入渗影响的基础上开展试验研究.在试验研究过程中,选取完整的路面结构层且不受降雨水分影响的固定含水率路基土体试样与带裂缝的路面结构层且受降雨水分影响的可变含水率路基土体试样,对不同情况下的粉质黏土试样开展无侧限抗压试验.结果表明:(1)固定含水率试样在受压情况下,试样破坏模式主要有剪切破坏、张拉破坏、共轭拉剪破坏和劈裂张拉破坏4种类型.试样在水分入渗后其湿润锋呈水平环状向下渗透,可变含水率试样在降雨水分入渗后其湿润锋呈“V”形下渗,形成优先流状态.(2)路基土样经无侧限压缩试验后其应力-应变曲线可分为:压密阶段、线弹性变形阶段、屈服阶段和破裂阶段.其无侧限抗压强度随含水率及降雨量的增加而降低,试样应力-应变曲线的应力峰值减小且后移,平稳阶段的应变范围增大.(3)可变含水率的降雨条件中,在试样初始含水率一定,历经小、中、大3种不同雨况下,试样无侧限抗压强度较固定含水率试样的抗压强度下降约14%.

In response to the problem of asphalt pavement cracks caused by rainwater infiltration affecting the roadbed soil,such as frost heave,experimental research is conducted based on the influence of water infiltration on the silty clay roadbed.During the experimental research process,a fixed moisture content roadbed soil sample with a complete pavement structure layer that is not affected by rainfall moisture was selected,and a variable moisture content roadbed soil sample with a cracked pavement structure layer that is affected by rainfall moisture content was selected.Unconfined compressive tests were conducted on powder clay samples under different conditions.The results indicate that:(1)Under compression,the failure modes of fixed moisture content specimens mainly include four types:shear failure,tensile failure,conjugate tensile shear failure,and splitting tensile failure.After water infiltration,the wetting front of the sample appears as a horizontal circular downward infiltration,while the wetting front of the variable moisture content sample appears as a"V"shaped downward infiltration after rainfall water infiltration,forming apreferential flow state.(2)The stress-strain curve of the roadbed soil sample after unconfined compression test can be divided into:compaction stage,linear elastic deformation stage,yield stage,and fracture stage;The unconfined compressive strength decreases with the increase of moisture content and rainfall,the stress peak of the stress-strain curve of the sample decreases and moves back,and the strain range in the stable stage increases.(3)Under variable moisture content rainfall conditions,the unconfined compressive strength of the sample decreases by about 14%compared to the compressive strength of the fixed moisture content sample under three different rainfall conditions:small,medium,and large,with a constant initial moisture content of the sample.