天然硅藻土的应力水平与孔隙空间分布的关系

Relationship between entrance pore distribution and stress level of natural sedimentary diatomaceous soil

采用压汞法研究了不同固结压力作用下具有强结构性的天然沉积硅藻土的微观孔隙入口孔径分布与应力水平的关系。研究结果表明:当应力水平小于固结屈服应力时,具有强结构性的天然沉积硅藻土的微观孔隙入口孔径分布几乎与应力水平无关,而当外加应力水平达到固结屈服压力时,虽然总体孔隙空间体积几乎与天然沉积状态时一样,但其微观孔隙入口孔径分布则发生显著变化。在屈服后阶段,随着应力水平的增大硅藻土的孔隙空间体积逐渐减少,最大孔隙变小,整体孔隙空间的孔径趋于均匀。并对微观结构变化与宏观力学特性的内在联系也进行了初步探讨。

The natural normally-consolidated diatomaceous soil deposited in Ohita Prefecture of Japan is a natural strongly structured soil. It has a surprising high strength and high consolidation yield stress although its natural water content is very high. In this study, the mercury intrusion porosimetry (MIP) tests were performed on the natural sedimentary diatomaceous soil to investigate the relationship between the change in entrance pore size distribution and the applied stress level. The microstructure investigation results indicate that the entrance pore size distribution varies little when the stress level is smaller than the consolidation yield stress, but changes significantly when the applied stress is in the vicinity of the consolidation yield stress. When the applied stress is larger than the consolidation yield stress, pore space volume decreases, the maximum pore becomes smaller and the pore size gradually becomes uniform with the increase of applied stress level. The relationship between microstructure and macro-mechanical behavior is also investigated.