二灰稳定三峡库区风化砂三轴试验研究

以三峡库区风化砂为研究对象,将其用石灰与粉煤灰质量比为1∶2,1∶3,1∶4的二灰进行稳定加固处理,其中石灰剂量分别为4%,5%,6%,然后进行不固结不排水三轴剪切试验,得到不同二灰掺量下的风化砂抗剪强度指标,并将三轴试验结果与直剪试验结果进行对比分析。结果表明:二灰稳定风化砂试件在不同围压下的应力-应变关系表现为应变软化型;二灰掺量的改变对二灰稳定风化砂内摩擦角的变化影响较小,而对黏聚力的变化影响较剧烈;当石灰的掺入比例一定时,黏聚力随着粉煤灰掺量的增大而增大,而内摩擦角随着粉煤灰掺量的增大呈现先增大后减小的趋势。对比三轴试验和直剪试验结果发现,通过三轴试验得到的黏聚力大于直剪试验得到的黏聚力,但二者得到的内摩擦角相差不大。研究结果可为三峡库区废弃风化砂的再生利用提供参考。

Triaxial Test on Weathered Sand from Three Gorges Reservoir Area Stabilized by Lime-Flyash

Unconsolidated-undrained triaxial shear test was conducted on weathered sand from the Three Gorges Reservoir area stabilized by lime-fly ash. The ratio of lime to fly ash was 1∶2, 1∶3, 1∶4, and the corresponding lime dosage was 4%, 5%, and 6%. The shear strength indexes of weathered sand stabilized by different dosages of lime-fly ash were obtained, and then the results of triaxial test were compared with those obtained by direct shear test. Conclusions are as follows: 1) the stress-strain curve of weathered sand stabilized by lime-fly ash displays strain softening feature under different confining pressures; 2) the change of lime-fly ash content in specimens exerts little impact on the internal friction angle, but dramatic impact on cohesion; 3) at a stable lime content, cohesion increases with the rise of fly ash content, while internal friction angle increases but then declines with the rise of fly ash content. Comparison between triaxial test and direct shear test results reveals that the cohesion obtained by triaxial test is greater than that by direct shear test, but the value of internal frictional angle shows little difference.