Abstract: Pneumatic deep loosening is a new deep loosening technology, which works by injecting highpressure gas into the bottom layer of the plow to create cracks and achieve deep loosening operations. Compared to traditional mechanical deep loosening, it has the characteristics of good deep loosening effect, less soil movement, and difficulty in changing the structure of the plow layer. In order to obtain and analyze the crack propagation characteristics during air pressure subsoiling, an indoor simulation experiment was conducted based on the analysis of the theoretical model of crack propagation. The results showed that the soil surface rose significantly during air pressure subsoiling, and the crack propagation mechanism conformed to the lifting and tensioning mechanism. When the unit weights of the plow bottom are 1.4 g/cm3, 1.6 g/cm3 and 1.8 g/cm3, under an air pressure of 1.8 MPa, the maximum radius of soil crack propagation is 0.55 m, with a maximum width of the crack of 3.23 mm, 9 mm and 8.13 mm, respectively. The unit weight of the plow bottom had an obvious but not positive correlation with the crack propagation width. The crack width decreased when the distance from the gas injection point increased. The experimental result was consistent with the theoretical analysis that crack propagation is a coupling of three processes: air pressure attenuation, gas leakage in soil, and soil displacement.

Key words: air pressure subsoiling, plow bottom, highpressure gas, crack propagation

摘要： 气压深松通过对耕地犁底层内注入高压气体，使其产生裂隙实现深松作业。与传统机械式深松相比，气压深松具有深松效果好、动土量少、不易改变耕层结构等特点。为获得气松过程中犁底层内裂隙扩展特性及规律，在分析气压深松裂隙扩展理论模型基础上，同时进行气压深松室内模拟试验。试验结果表明：气压深松时，土表抬升明显，裂隙扩展机理符合抬升张拉机理，容重1.4g/cm3、1.6g/cm3、1.8g/cm3犁底层，在1.8MPa的气压作用下，土体裂隙扩展最大半径为0.55m,裂隙最大宽度为3.23mm、9mm、8.13mm，犁底层容重对裂隙扩展宽度影响明显但并非正相关，裂隙宽度随注气点距离的增加而减小。试验结果与理论分析表述一致，即气压深松裂隙的扩展为气压衰减、气体土内泄露、土体位移三个过程的耦合作用。

关键词: 气压深松, 犁底层, 高压气体, 裂隙扩展