压实石英颗粒中孔隙水微观动力学性质研究

Microdynamic Properties of Pore Water in Compacted Quartz Particles

土水作用使土体中孔隙水具有与自由水完全不同的物理状态,从而影响了土体的物理特性。作为地球表面含量最多的矿物之一,石英广泛存在于各种岩土体中,石英颗粒与水的相互作用极大的影响各种岩土体的工程特性。为了研究石英颗粒与水的相互作用,利用核磁共振技术探测了非饱和压实石英颗粒中不同温度条件下的纵向弛豫时间T_(1)分布曲线和常温下T_(1)-横向弛豫时间T_(2)相关谱图。通过分析孔隙水T_(1)/T_(2)分布曲线,发现峰点处T_(1)/T_(2)约为6.31。基于BPP(Bloembergen-Purcell-Pound)模型,计算得到非饱和石英土样中孔隙水分子的转动特征时间远大于自由水的转动特征时间,说明压实石英颗粒中的孔隙水活动度受到较大的抑制。利用Korb模型,计算得到了吸附水在石英颗粒表面的特征停留时间和亲和性。结果表明:水分子在离开石英颗粒表面时在颗粒表面移动了4.2×10^(9)步,说明石英颗粒对水分子具有较大的亲水性或束缚性。基于Arrhenius定理分析T_(1)分布曲线随温度的变化得到石英颗粒中表面吸附水的吸附活化能为26.8 kJ/mol,远大于黏土颗粒表面吸附水的吸附活化能。这表明石英颗粒表面对水分子的束缚作用大于黏土颗粒表面。经分析认为这主要是因为石英颗粒表面的硅醇基与表面吸附水形成大量的氢键使得石英颗粒对表面吸附水具有较大的束缚作用。

The physical properties of soil are affected by soil-water interaction,which makes pore water in soil has a completely different physical state from that of free water.As one of the most abundant minerals in the crust of the Earth,quartz widely exists in many kinds of rocks and soils.The interaction between quartz particles and water greatly affects the engineering characteristics of rocks and soils.To study the interaction between quartz paticle and water,nuclear magnetic resonance technology was used to detect the spin lattice relaxation time T_(1)distribution curves at different temperatures and the T_(1)-transverse relaxation time T_(2)correlation spectra at room temperature for unsaturated compacted quartz particles.Through the analysis of T_(1)/T_(2)distribution curve,it is found that the T_(1)/T_(2)ratio at the peak point is about 6.31.With Bloembergen-Purcell-Pound(BPP)model,the rotational characteristic time of pore water molecules in unsaturated quartz sample was calculated which was much longer than that of free water,indicating that the mobility of pore water in sample was greatly depressed.Using Korb model,the characteristic residence time and affinity of adsorbed water on the surface of quartz particles were calculated.The results show that the water molecules move 4.2×10^(9) steps on the sand surface before leaving the quartz surface,indicating that the quartz particle has a large hydrophilic or binding property to water molecule.The varation of T_(1)distribution curve with temperature was analyzed based on Arrhenius theorem.It is found that the adsorption activation energy of surface adsorbed water on quartz particle is 26.8 kJ/mol,which is much higher than that of surface adsorbed water on clay particles.The result indicates that the binding effect of quartz particles on water molecules is greater than that of clay particles.This is mainly because the a large number of hydrogen bonds between silanol group on the surface of quartz particles with the adsorbed water,which makes the quartz particles have a great binding effect on the adsorbed water on the surface.