压实全风化红层泥岩填料力学特性及其影响因素

Mechanical Properties and Influencing Factors of Compacted Completely-Weathered Red Mudstone Filling Material

将全风化红层泥岩压实后用作高速铁路路基填料可以有效缓解西南地区优质填料缺乏的现状,但前期变形路径对压实全风化红层泥岩填料力学特性的影响规律尚不明确。为此,采用一维膨胀试验、直剪试验及压汞试验,研究前期变形路径对压实全风化红层泥岩填料力学特性的影响规律,并揭示其影响机理。结果表明:压实全风化红层泥岩填料在浸水后的膨胀变形可分为初次膨胀、二次膨胀及变形稳定3个阶段,初始干密度越大、初始含水率越低、竖向荷载越小,膨胀率和二次变形系数越大;初始状态相同时,膨胀-固结路径下压实全风化红层泥岩填料的膨胀率和膨胀力大于固结-膨胀路径下的;前期变形路径对抗剪强度的影响较小,但固结-膨胀路径下填料应力-位移曲线由软化向硬化的过渡较膨胀-固结路径表现出明显的滞后性;固结-膨胀路径下压实全风化红层泥岩填料特征孔径比膨胀-固结路径下的分布密度更低、数量更少。

The compacted completely-weathered red mudstone could be used as the filling material of high-speed railway subgrade to effectively ease the problem of high-quality filling material shortage in Southwest China.However,the influence laws on pre-deformation path of the mechanical properties of compacted completelyweathered red mudstone is still unclear.Therefore,the one-dimensional swelling test,direct shear test and mercury intrusion porosimetry test are carried out to study the influence laws on pre-deformation path of the mechanical properties of compacted completely-weathered red mudstone;and the influence mechanism of predeformation path is revealed.The results show that the deformation of the compacted completely-weathered red mudstone after immersion can be divided into three stages-the initial swelling,the secondary swelling and the stable deformation.The greater the initial dry density,the lower the initial water content and the less the vertical load,resulting in greater initial swelling ratio and secondary deformation coefficients;when the initial states are the same,the swelling ratio and the swelling pressure of compacted completely-weathered red mudstone filling material under the swelling-consolidation path are greater than those under the consolidationswelling path.The pre-deformation path has minor effects on the shear strength,but the stress-displacement curve of the filling material shows more obvious hysteresis when transiting from softening to hardening under the consolidation-swelling path,compared with the one under the swelling-consolidation path.The pre-deformation path reveals lower distribution density and smaller number of characteristic micropores in the compacted completely-weathered red mudstone under the consolidation-swelling path compared with the swellingconsolidation path.