高含水率疏浚淤泥生石灰材料化土闷料期内强度变化规律

研究了3种初始含水率疏浚淤泥添加不同比例生石灰,经不同时长的闷料期,其击实土的强度及变形变化规律.试验结果表明:击实生石灰淤泥材料化土的无侧限抗压强度随闷料期增大而增大,且强度增加速率和掺灰比有关,掺灰比越大,强度增加速率越大.对应不同初始含水率的疏浚淤泥,掺灰比存在临界点,该临界点是生石灰淤泥材料化土应力-应变关系由塑性向脆性转化的转折点.小于该掺灰比,生石灰淤泥材料化土单轴压缩下是理想弹塑性变形,大于该掺灰比,击实生石灰淤泥材料化土是脆性破坏变形.对于小于临界掺灰比的生石灰淤泥材料化土,延长闷料期,其击实土应力-应变关系有由塑性向脆性转化的趋势,但是改良效果缓慢;对于大于临界掺灰比的生石灰淤泥材料化土,延长闷料期,其击实土的强度有显著提高.实际工程中如果场地条件及工期允许,可以通过延长闷料期改善土性,从而减小掺灰比,以节省工程造价.

Strength variation rules of filling soil improved from high-water-content dredged sludge with quicklime during delay time

The strength and deformation variation rules of the filling soils improved from 3 kinds of high-water-content dredged sludge with lime treated with different initial water contents and delay time were studied. The experimental results indicate that the unconfined compressive strength of the compacted soil increases with the increase of the delay time. The increase rate relates to the lime content. The larger the lime content, the higher the increase rate of the unconfined compressive strength. As for the dredged sludge with different initial water contents, there is a critical lime content for the mixing proportion, which is the turning point of the soil from the stress-strain relationship to the plastic-brittle one. The soil with a mixing proportion smaller than the critical lime content under the uniaxial compression deformation exhibits ideal elastic-plastic deformation, and the compacted soil with a mixing proportion larger than the critical lime content exhibits brittle failure deformation. As for the former, if the delay time extends, the stress-strain relationship of the compacted soil will show a tendency from plasticity to brittleness and have slow conversion efficiency. As for the latter, if the delay time extends, the strength of the compacted soil will have a significant increase. In the engineering practices, if the site conditions and the construction period are allowable, the delay time should be extended so as to improve the soil properties and to reduce the lime content and to save project cost.