含水率及干密度对高铁泥岩地基土无荷膨胀率的影响

Influence of water content and dry density on free swell ratio of high speed railway mudstone foundation soil

通过室内无荷膨胀试验,研究初始含水率与初始干密度对高速铁路泥岩地基土无荷膨胀率的影响。研究结果表明:无荷膨胀率随时间的变化规律可分为快速膨胀、减速膨胀和膨胀稳定3个阶段。在相同初始干密度情况下,膨胀率随时间增长而逐渐增大,并且试样初始含水率越低,最终达到胀限含水率时的膨胀率越大。无荷膨胀率随初始含水率的增大而减小,干密度越大,无荷膨胀率减小的速率越快;无荷膨胀率随初始干密度增大而增大,在不同含水率条件下膨胀率增长速率有所不同。试样越干燥、干密度越大,其膨胀潜能越大。对无荷膨胀率时程曲线和无荷膨胀率-初始含水率-初始干密度三者关系分别用半对数函数和二元线性函数进行拟合,拟合结果良好,可较好地预测泥岩地基实际变形情况。

The effect of initial water content and initial dry density on the free swell ratio of high-speed railway mudstone was studied by the indoor free swell test.The results showed that the change rule of time-free curve of free swell ratio can be divided into three stages:rapid expansion,deceleration expansion and stable expansion.In the case of the same dry density,the swell ratio gradually increased with time,and the lower the initial water content of the sample was,the greater the swell ratio at which the water content of the expansion limit reached.The free swell ratio decreased with the increase of the initial water content.The larger the initial dry density,the faster the rate of free swell ratio decreased.The free swell ratio increased with the initial dry density,and the growth rate of free swell ratio was different at different moisture contents.The drier and denser the initial state of the sample was,the greater the expansion potential was.In addition,the relationship between the free swell ratio time-course curve and the free swell ratio-initial moisture content-initial dry density could be satisfying fitted by the semi-logarithmic function and the binary linear function,respectively;and could be better predicted the actual deformation of mudstone.