生物炭近年来在环境岩土工程中得到了广泛的应用。然而,它对土壤开裂的影响尚不完全清楚。在这项研究中,研究了不同木材生物炭用量对粉质粘土干裂特性的影响,并通过图像和微观结构分析的结合阐明了机理。结果表明,生物炭在水分蒸发和裂缝发育的整个过程中都会影响土壤的干裂特性。生物炭用量低,蒸发速率降低,但随着生物炭含量的增加而增加。在裂纹发展阶段,生物炭的添加增加了土壤裂解水含量,诱导土中环形裂缝的形成,改变了土壤裂缝的发展过程。稳定裂纹的定量结果表明,表面裂纹率分别下降了11.59%和34.32%,平均裂缝宽度减少了14.83%,34.51%,添加5%和10%生物炭后,分别。同时,生物炭改良土壤中的大多数单裂缝是细的。此外,随着干湿(W-D)循环次数的增加,未添加生物炭的土壤表面裂缝率首先增加,然后稳定,而生物炭改良土壤的含量略有下降。比较一个和五个W-D循环后的裂纹网络,添加5%和10%生物炭形成的裂缝数量减少了-1.51%和19.24%,和15.29%,和36.92%,分别,表明在添加生物炭后,在W-D循环下,土壤变得更耐开裂。总之,生物炭的添加可以通过(1)降低土壤表面的拉伸应力来抑制干燥开裂,(2)增加土壤颗粒之间的排斥力,(3)占用土粒之间的收缩空间,(4)降低土粒之间的抗拉强度。
Biochar has recently been widely used in environmental geotechnical engineering. However, its impact on soil cracking is not fully understood. In this study, the influence of different wood biochar dosages on the desiccation cracking characteristics of silty clay was studied, and the mechanism was elucidated through a combination of image and microstructural analysis. The results indicate biochar affects the desiccation cracking characteristics of soil across the whole process of water evaporation and crack development. The evaporation rate decreased with low amounts of biochar, but increased as the biochar content increased. At the stage of crack development, the addition of biochar increased the soil cracking water content, induced the formation of annular cracks in soil, and changed the soil crack development process. Quantitative results of the stabilized cracks show the surface crack ratio was decreased by 11.59% and 34.32%, and the average crack width was decreased by 14.83%, and 34.51%, after 5% and 10% biochar addition, respectively. Meanwhile, most of the single cracks in biochar-amended soil are fine. In addition, the surface crack ratio of soil without biochar addition first increased and then stabilized with an increase in the number of wetting-drying (W-D) cycles, while that of the biochar-amended soil decreased slightly. Comparing the crack networks after one and five W-D cycles, the number of cracks formed with 5% and 10% biochar addition decreased by -1.51% and 19.24%, and 15.29%, and 36.92%, respectively, indicating that after the addition of biochar, the soil becomes more resistant to cracking under W-D cycles. In summary, the addition of biochar may have inhibited desiccation cracking by (1) reducing the tensile stress on the soil surface, (2) increasing the repulsive forces between soil particles, (3) occupying the shrinkage space between soil particles, and (4) reducing the tensile strength between soil particles.