基于高精度μCT扫描的重塑黄土试样均匀性分析

Uniformity of Remoulded Loess Samples Based on High Precision μCT Scanning

研究重塑黄土试样实验室内的制备效果,为工程活动提供准确的指标参数。以压实与击实2种制样方法所制备的三轴重塑黄土试样为对象,通过高精度μCT扫描试验,借助VGStudioMAX2.2图像处理软件,实现了土样微结构的三维重建,量化分析试样结构、孔隙三维信息以及孔隙分布情况,并通过三轴剪切试验简要分析了孔隙均匀性和围压对极限强度的影响。结果表明:①分层压实易造成重塑样内部结构的严重破坏,而不同工序下的分层击实试样孔隙分布极不均匀;一次压实试样较击实试样体积主频率孔径降低了40μm,且不同区域的孔隙率差值<3%。②土体内孔隙率分布差距越大,其极限强度越小。重塑样孔隙空间分布影响测得的黄土特性,故宜采用一次压实法制重备塑黄土样。

The effect of preparing remoulded loess samples by different methods in laboratory is studied in this paper to provide accurate index parameters for geotechnical engineering.Triaxial remoulded loess samples prepared by pressing and bumping were scanned by high precisionμCT to reconstruct the soil’s microstructure in three dimensions by VG Studio MAX2.2 image processing software.The structure,3D information of pores,and pore distribution of loess samples were quantified;the influences of pore uniformity and confining pressure on the ultimate strength of loess samples were examined by means of triaxial shear test.Results show that:(1)layered pressing is prone to result in severe damage to the internal structure of loess sample;layered bumping lead to the non-uniform distribution of pores.The pore size of main volume frequency of samples undergone one-time pressing is 40μm smaller than that of bumped samples,and the difference of porosity in different zones is less than 3%.(2)The greater the gap between the soil porosity distribution,the smaller the ultimate strength.Conclusion was drawn as follows:the characteristics of loess is affected by the spatial distribution of porosity,and one-time bumping method is recommended for the preparation of remoulded loess sample.