广州饱和软土固结过程微孔隙变化的试验分析

软土的孔隙特征及其变化规律对软土的压缩性和渗透性有重大的影响,软土孔隙特征随荷载变化规律的试验研究为揭示软土排水固结过程与变形规律,建立基于孔隙压缩规律和渗流机制的排水固结模型提供有力依据。利用美国全自动压汞仪,对不同压力下固结的广州番禺淤泥土样的孔隙及其尺度分布进行测试,根据测试结果对土样孔隙尺度分布特征及其随固结压力的变化规律给出了定量分析。试验结果表明:淤泥土中介于0.4～2.5μm范围的颗粒间及团粒内的小孔隙所占比例最大,而大于10μm的大孔隙和小于30nm的超微孔隙所占比例均很小;较大的孔隙更易于被压缩而湮灭或被分裂成微小孔隙;固结压力将显著改变淤泥土的孔隙尺度及其分布特征,以致改变土体的压缩性和渗透性。在固结前期(p200kPa)孔隙尺度较大,压缩系数和渗透系数较大并随固结压力增加而快速减小;在固结后期(p200kPa)孔隙尺度小,压缩系数和渗透系数小,且随固结压力增加的变化趋于平缓。

Experimental analysis of micropore change of Guangzhou saturated soft soil in consolidation process

The pore characteristics and the change rule of soft soils have significant influence on their compressibility and permeability. The study can reveal the drainage consolidation process of soft soil and its deformation law so as to provide a strong basis for establishing draining water solidifying model based on the pore compression mechanism of drainage patterns and flow model. AutoPore machine made in United States was used to test pore diameter and pore-scale distribution of Guangzhou Panyu silt soil under different load levels, then gave the quantitative analysis of pore criterion distribution characteristics according to the test results. The studied results have shown that: small pores within particles and aggregates intermediated in the range of 0.4-2.5 μm is the largest proportion in the sludge soil; the number of large pores larger than 10 μm and micro pores less than 30 nm is very small; more large pore more easily be compressed and annihilated or splited into tiny pores; consolidation pressure will significantly change pore scale and pore distribution characteristics of the silt soil which results in the changes of its compressibility and permeability. Pore-scale is greater in the early stage of consolidation( 200 kPa); compression coefficient and permeability coefficient are large and rapid decrease with the increasing consolidation pressure; and pore scale is small in the late consolidation( 200 kPa); compression coefficient and permeability coefficient are small, and with the consolidation pressure change flatten out.