风化千枚岩填筑路基湿化变形现场试验分析

Field experimental analysis of wetting deformation of filled subgrade with weathered phyllite

为了分析千枚岩填筑路基浸水后的稳定性,对十堰至天水高速公路安康东段路基的湿化变形及回弹模量进行现场测试。在对风化千枚岩填料物理力学性质分析的基础上,提出路基填筑方案:加州承载比CBR>3%的风化千枚岩填料直接填筑路基;CBR<3%的风化千枚岩填料外掺3%水泥改良后填筑路基。通过对现场试验路进行浸水前后的承载板测试,分析浸水量、浸水时间对湿化变形、变形率及路基回弹模量的影响;结合不同深度含水率的测试,分析了测试点含水率和渗水深度与湿化变形的相关性。研究结果表明:浸水量和浸水时间是影响路基渗透深度和含水率的关键因素,未改良路基湿化变形受浸水影响比改良路基要明显;浸水量和浸水时间都相同的情况下,未改良路基浸水后回弹模量衰减比改良路基大。

In order to analyze the stability of soaked subgrade filled with weathered phyllite, wetting deformation and resilient modulus of the subgrade are tested in field at Ankang eastern section of Shiyan-Tianshui expressway. Based on physico-mechanical property analysis of weathered phyllite, filling scheme of subgrade is put forward： for subgrade filled material with weathered phyllite California bearing ratio （CBR） 〉3%, the weathered phyllite is filled into the subgrade directly; for CBR〈3%, the weathered phyllite is filled into the subgrade after improved with additive 3% cement. Through bearing plate field tests before and after immersion on the test road, the influence of soaking amount, soaking time on wetting deformation, rate of wetting deformation and resilient modulus of subgrade are analyzed. Combined with water content test of the test points in different depths, relationships between water content, seepage depth and wetting deformation are analyzed. The results indicate that soaking amount and soaking time are key factors that affect the seepage depth and water content; the wetting deformation of soaked common subgrade is more obvious than that of soaked improved subgrade. When both soaking amount and soaking time are equal, the resilient modulus attenuation of common subgrade is larger than that of improved subgrade.