固化土双向制样仪研发与制样效果多尺度对比

Development of a bidirectional sample preparation instrument for solidified soil and multiscale comparison of the sample preparation effect

该文研发了一款电动双向固化土试样制样仪,通过与击实法及静压法制样的试样进行宏观、细观、微观对比,分析验证双向制样仪的可行性。结果表明:在宏观层面上,双向试样固化土无侧限抗压强度最高,静压试样次之,而击实试样最低;双向试样固化土整体外观颜色一致且破坏形式稳定,均为剪切破坏,均匀性优于击实法和静压法试样。在细观层面上,双向试样的表观孔隙最少且分布均匀。在微观层面上,双向试样内部微观结构最致密,进汞量最少,孔隙体积占比以直径较小的颗粒间孔隙为主。因此,多尺度对比研究表明,自主研发的双向制样仪的制样效果优于静压仪和三瓣模(或双瓣模),可在土工试验中推广应用。

[Objective]This paper focuses on the development of a bidirectional consolidated soil sample-making apparatus.The aim is to compare samples made by this apparatus with those created using compaction and static pressure methods and to analyze and verify the feasibility of the bidirectional properties.[Methods]In this paper,three types of test equipment were used to prepare consolidated soil samples of specified age.Several comparative tests were conducted,such as the unconfined compressive strength(UCS)test,the industrial electron microscopy test,the scanning electron microscopy test,and the mercury-in-pressure porosimetry test.These tests helped analyze and verify the feasibility of the bidirectional consolidated soil sample maker.They also enabled us to study the macro/fine/micro characteristics of the samples produced by the three test equipment from various angles,such as UCS and its destructive form,apparent porosity of the sample,microscopic porosity and filling of the curing product,microscopic pore volume,and pore size distribution.[Results]The results show that in terms of macro UCS of consolidated soil samples,the bidirectional sample has the highest UCS,followed by the static pressure sample and then the compaction sample.In terms of sample formation and destruction form,the bidirectional sample is uniform in color and has a stable destruction form(all are shear destruction).The static pressure sample is denser at the top and looser at the bottom,with destruction mostly in the weaker and lower parts.The compaction sample,however,shows distinct layering with varying shades and multiple forms of damage.Thus,the uniformity of the bidirectional sample is superior to that of the compacted and static compaction samples.Upon fine analysis,we found that compared with the static compaction sample(which has an apparent porosity that gradually increases from top to bottom)and the compaction sample(where the apparent porosity gradually decreases from top to bottom),the bidirectional sample has the smallest and most uniformly distributed apparent porosity.At the microscopic level,the bidirectional sample has the highest amount of curing products that can effectively fill the pores,making its internal microstructure the densest.It also has the least amount of mercury intake and is dominated by interparticle pores with smaller diameters.This is followed by the static pressure sample,while the compaction sample has the least amount of curing products,larger pores,the highest amount of mercury intake,and pores mainly distributed in the interparticle pores with larger diameters and the intragranular pores.[Conclusions]Therefore,the multiscale comparative study shows that the self-developed bidirectional sample-making instrument is better than that of the static pressure instrument outperforms both the static pressure and the three-segment mold(or double membrane)in terms of sample making.Not only does it deliver superior results,but it also exhibits a smaller margin of errors in tests.Consequently,this makes it a viable option for widespread adoption and application in geotechnical tests.