重载铁路路基土动力特性试验研究

Experimental Study on Dynamic Performance of Subgrade Soil for Heavy Haul Railway

通过动三轴试验研究巴准（巴图塔—点岱沟）重载铁路路基土在不同含水量、围压和频率下的动力特性。结果表明：路基土骨干曲线近似为双曲线,动剪切应力随动剪切应变、围压的增加而增加,随含水量的增加而减小;加载频率对路基土骨干曲线影响不明显,2-3 Hz为路基土临界频率;路基土最大动剪切模量与含水量、围压、频率呈衰减变化趋势;动剪切模量比与动剪切应变比具有很好的归一性,基于此给出考虑含水量、围压和频率影响的动剪切模量经验公式;路基土阻尼比随围压增加而减小;不同频率路基土阻尼比集中于一狭小范围内,频率对路基土阻尼比影响不明显。

Dynamic properties of subgrade soils of Bazhun（ Batuta-Diandaigou） heavy haul railway with varied water content were investigated by dynamic triaxial tests under different confining pressures and loading frequencies.Test results showed that the skeleton curves of the soils appeared to follow hyperbola approximately. The dynamic shear stress increased with increasing dynamic shear strain, confining pressure,whereas decreased with increasing in water content. The influence of loading frequency seemed insignificant on skeleton curves,where the critical frequency was ranged from 2 Hz to 3 Hz. The maximum shear modulus of the subgrade soils degraded with increasing water content,confining pressure and loading frequency. Meanwhile,dynamic shear modulus ratios and strain ratios presented well-defined linear normalization properties,and accordingly an empirical expression used to estimate dynamic shear modulus was formulated accounting for the effects of water content, confining pressure and frequency of cyclic loading. Damping ratio decreased with increasing in confining pressure. The damping ratios of the subgrade soils under different loading frequencies distributed in a small region,where loading frequency negligibly affected the damping ratio.