基于核磁共振技术的疏浚淤泥固化土孔隙水含量及分布研究

摘要

Low field proton nuclear magnetic resonance (NMR) technology is used to measure the distribution of transverse relaxation time T2 of solidified dredging silt soil to study the content and distribution law of pore water in solidified soil.Results show that there is only one main peak in the distribution of relaxation time of solidified soil samples of different cement dosages ; the peak area decreases gradually with the growth of curing age and the in -crease of cement dosage.Pore water content decreases gradually , and the decrease first starts from big pores .The main effect of curing age is reducing the moisture content in the big pores , whereas cement is not only beneficial for reducing the moisture content in the big pores , but also the moisture in the small pores .With the growth of curing age and the increase of cement dosage , the scope of T2 distribution of solidified soil narrows and the distribution tends to short relaxation time, and pore water is distributed in smaller pores gradually .The weighted average relaxa-tion time T2 declines rapidly with the growth of curing age first , and the decline rate decreases gradually after 7 days.Solidified soil’s total nuclear magnetic signal amplitude of T2 shows an overall trend of decrease with the cu -ring age growth, and the speed slows down after 7 days; this is because the water is consumed or converted into mineral water due to internal chemical reaction in solidified soil .Nuclear magnetic resonance (NMR) technology can well present the content and distribution law of pore water in the process of solidification .%为研究疏浚淤泥固化土中孔隙水的含量及分布规律，利用低场质子核磁共振技术探测疏浚淤泥固化土的横向弛豫时间 T2分布曲线。结果表明：各水泥掺量下淤泥固化土样品的弛豫时间分布只有一个主峰，峰面积随着养护龄期的增长和水泥掺量的增大均逐渐减小，孔隙水的含量逐渐减小，并且孔隙水的减少首先是从大孔隙水分开始的，龄期的主要作用是减小大孔隙里的水分含量，而水泥不仅有利于大孔隙水分含量的减小，也有利于小孔隙水分含量的减小；随着养护龄期的增长和水泥掺量的增大，淤泥固化土的 T2分布范围变窄，分布趋向于短弛豫时间，孔隙水逐渐分布在较小的孔隙中；加权平均 T2弛豫时间随着龄期的增长先快速下降，7 d 后下降的速率逐渐减小，固化土 T2总核磁信号幅值随养护龄期的变化总体呈减小趋势，速度超过7 d 后减慢，这是因为淤泥固化土内部的化学反应使得水分被消耗或转化成了矿物水。研究表明核磁共振技术能较好地呈现淤泥固化过程中孔隙水含量及分布的变化规律。