Abstract：
Desiccation cracking can significantly change the integrity of soils, and potentially result in the instability of infrastructure as well as the migration of contaminants. Biochar is regarded as a promising low-carbon material for geotechnical applications, including cracking prevention. This study investigates the effects of biochar particle size and dosage on the desiccation cracking characteristics of a silty clay. For samples with fine biochar particles (<0.25 mm), coarser primary cracks initiate first, followed by finer secondary cracks regardless of biochar dosage. Quantitative analysis of the cracking characteristics at the stable stage shows that the surface crack ratio, the number of crack segments, the total length of cracks and the average width of cracks decreased by 31.29%, 30.78%, 14.18%, and 20.45% after 10% biochar addition. For samples with coarse biochar particles (>0.25 mm), cracks initiate simultaneously on the soil surface, and primary and secondary cracks are difficult to distinguish after drying, especially in high dosage samples. In the presence of 10% biochar, the surface crack ratio and average width of cracks decreased by 28.64% and 62.84%, but the number of crack segments and total length of cracks increased by 163.39% and 42.13%. Microstructure and image processing analysis of soil cracks indicate that biochar affects the crack initiation and propagation process by altering the soil microstructure and thereby the crack parameters. The contact between biochar and soil particles transitions from close contact to loose contact as the size of the biochar particles increases. In general, the application of 10% biochar with fine particle size had the best performance in inhibiting soil cracking.
摘要：
干燥开裂可以显著改变土壤的完整性，并可能导致基础设施的不稳定性以及污染物的迁移。生物炭被认为是一种很有前途的用于岩土工程应用的低碳材料，包括开裂预防。本研究研究了生物炭粒径和用量对粉质粘土干燥开裂特性的影响。对于具有细生物炭颗粒（<0.25mm）的样品，较粗的初级裂纹首先开始，无论生物炭用量如何，其次是更细的二次裂缝。稳定阶段开裂特征的定量分析表明,表面裂纹比,裂纹段的数量，裂缝总长度和裂缝平均宽度减少了31.29%，30.78%,14.18%,添加10%生物炭后为20.45%。对于含有粗生物炭颗粒(>0.25mm)的样品，在土壤表面同时出现裂缝，干燥后难以区分一级和二级裂纹，特别是在高剂量样品中。在10%的生物炭存在下，表面裂缝率和裂缝平均宽度分别下降了28.64%和62.84%,裂纹段数和裂纹总长度分别增加了163.39%和42.13%。土壤裂缝的微观结构和图像处理分析表明，生物炭通过改变土壤微观结构，从而影响裂缝的萌生和扩展过程。随着生物炭颗粒尺寸的增加,生物炭和土壤颗粒之间的接触从紧密接触转变为松散接触。总的来说,10％的细粒径生物炭在抑制土壤开裂方面具有最佳性能。
