荷载-干湿循环共同作用下泥岩的压缩特性

Effects of drying-wetting cycle and loading on compressive property of mudstone

泥岩遇水易崩解泥化,特别是耦合荷载作用后,其力学性能衰减更加明显。为掌握泥岩在环境因素和外部荷载作用下的性能演化规律,开展了干湿循环与上覆荷载共同作用下的压缩特性试验。发现初次浸水后压实泥岩发生膨胀,但随着干湿循环作用的进行,泥岩试样发生压缩变形。然后,对压实泥岩试样进行孔隙分析,结果表明,泥岩孔隙分布呈现双峰特征,峰值大约位于0.3um和10.0um孔径处,干湿循环和荷载的作用引起孔隙体积减小,特别是对大孔径孔隙的影响最显著。最后,依据泥岩的膨胀、压缩和孔隙分布特征,提出了压实泥岩的孔隙-荷载-水分相互作用模型,将压实泥岩的孔隙体积分为团粒内孔隙和团粒间孔隙两类;分析了荷载-干湿循环引起泥岩团粒崩解破碎和充填团粒之间孔隙的演变过程。揭示了泥岩孔隙-水分-荷载的相互作用机制,为泥岩路基的填筑提供了理论参考。

Mudstone is sensitive to moisture,especially under loading coupled effect,its mechanical properties may decrease dramatically.The compression tests were carried out under loading and drying-wetting cycle joint effect to reveal the evolution process of mudstone performance with environment and loading influence.The compacted samples swelled when immerged into water for the first time.But,they would be compressed during drying-wetting cycle process subsequently.Then,pore size analysis testing was performed on compacted mudstone,the pore size distribution curves had two peaks,which corresponded to diameters 0.3 μm and 10 μm,respectively.Pore volumes reduced for drying-wetting cycle and loading joint effect,which was more obviously for large size pores.And,based on swelling testing,compression test and pore size distribution curves,one model about pore-moisture-loading interaction was established.The whole pore volume includes two parts,inter-volume and extra-volume of agglomerate.On the basis,the crushing-filling procedure of mudstone agglomerate was analyzed under drying-wetting cycle,and the mechanism of interaction between mudstone pore-moisture-load was revealed.This research can provide some theoretical references for mudstone subgrade construction.