饱和重塑黏性土固结过程的孔径分布特性研究

对饱和重塑黏性土采用不同加载速率进行排水固结,将不同加载时段的试样进行核磁共振(NMR)测量,分析横向驰豫时间T₂分布、T₂谱面积变化与孔隙的关系,研究饱和重塑黏性土固结过程的孔径分布特性。结果表明:饱和重塑黏性土试样初始阶段的横向驰豫时间T₂为两谱峰,分别代表大小孔径的孔隙,随着加载的进行,各试样组试样孔径逐渐向较小尺寸转移,最终变成致密均匀的小孔径孔隙;恒载一定时间后,孔径变化不再明显,说明孔隙中可流动流体已排尽,此时完成排水固结;根据加载速率与最大孔压的正相关关系得到一分界速率,合理推断控制加载速率小于该值,则主固结阶段即完成排水固结。

Study on Pore Size Distribution Characteristics of Saturated Remolded Clay during Consolidation

The saturated remolded clay was drained and consolidated at different loading rates, and the samples in different loading periods were measured by nuclear magnetic resonance (NMR). The relationship between transverse relaxation time T₂ distribution, T₂ spectral area change, and the porosity was analyzed; furthermore, the pore size distribution characteristics of saturated remolded clay during consolidation were studied. The results show that the transverse relaxation time T₂ of saturated remolded cohesive soil samples in the initial stage is two spectral peaks, representing the pores with large and small pore sizes, respectively. With the progress of loading, the pore size of each sample group gradually shifts to smaller sizes and finally becomes dense and uniform pores with small pore sizes. After a specific time of dead load, the change in pore diameter is no longer noticeable, indicating that the flowable fluid in the pore has been drained, and the drainage consolidation is completed at this time. A boundary rate is obtained according to the positive correlation between the loading rate and the maximum pore water pressure. If the controlled loading rate is less than this value, it is inferred that the drainage consolidation is completed in the main consolidation stage.