CAJ | 학술논문

　　该文对不同耕地类型土壤表面干缩裂缝的发展规律进行了室内试验研究，通过计算机图像处理，研究裂缝形态的统计规律。结果表明：裂缝面积密度和长度密度都是随着含水率的减少而增大，达到最大值后保持稳定。水田和旱田试样的连通性指数随着含水率的减小而增大，分别在质量含水率为20%和12%左右达到最大值并且稳定，最大值分别为0.935和0.598，反映了不同耕地类型下土壤干缩裂缝网络的形成过程和连通性的实际情况。裂缝面积和长度的概率密度和累积概率符合正态分布，裂缝面积和长度的概率密度实测值与概率密度函数的拟合决定系数分别大于0.94和0.91；裂缝面积和长度的累积概率实测值与分布函数的拟合决定系数分别大于0.90和0.94。可以用正态分布描述土壤表面裂缝的形态，有助于研究土壤干缩裂缝的形成机理以及不同裂缝形态对土壤优先流的影响。
　　해문대불동경지류형토양표면간축렬봉적발전규률진행료실내시험연구，통과계산궤도상처리，연구렬봉형태적통계규률。결과표명：렬봉면적밀도화장도밀도도시수착함수솔적감소이증대，체도최대치후보지은정。수전화한전시양적련통성지수수착함수솔적감소이증대，분별재질량함수솔위20%화12%좌우체도최대치병차은정，최대치분별위0.935화0.598，반영료불동경지류형하토양간축렬봉망락적형성과정화련통성적실제정황。렬봉면적화장도적개솔밀도화루적개솔부합정태분포，렬봉면적화장도적개솔밀도실측치여개솔밀도함수적의합결정계수분별대우0.94화0.91；렬봉면적화장도적루적개솔실측치여분포함수적의합결정계수분별대우0.90화0.94。가이용정태분포묘술토양표면렬봉적형태，유조우연구토양간축렬봉적형성궤리이급불동렬봉형태대토양우선류적영향。
Agricultural soil cracks generated during drying process becomes one of the causes of preferential flow. Generalizing crack network structure reasonably is an important research in the field. A laboratory experiment was carried out to investigate the law behind the development of shrinkage cracks on the soil surface under different types of cultivated land. In this investigation, computer image processing technique was applied to quantificationally analyze the statistical law of crack morphology and a dynamic description method based on normal distribution was proposed to depict the morphology of shrinkage cracks on soil surface. It showed that crack area density and length density both increased with decreasing moisture content and remained stable after reaching their maximums. Crack area density of paddy field (PF) specimen was a little bit bigger than that of upland field (UF) specimen throughout the drying process while the crack length density of both specimens didn't appear to be much different under the same mass moisture content. The connectivity index increased with decreasing moisture content and finally tended to be stable. The maximum connectivity index of PF specimen was 0.935 around a mass moisture content of 20% while for the UF specimen was 0.598 around a mass moisture content of 12%, reflecting that cracks of PF specimen were more closely connective to each other and the crack network of PF specimen formed faster. The connectivity index is applicable to account for the forming process and actual connectivity of shrinkage crack network under different types of cultivated land. Results suggested that crack area probability density and cumulative probability were in line with normal distribution. Both mean value and standard deviation had fairly good correlation with moisture content. Their coefficients of determination of UF specimen were larger than 0.99 and 0.98, respectively. The crack area coefficient of determination of different farmland types between the measured values and theoretical values of probability density function were both larger than 0.94, while for the crack length were both larger than 0.91, and their root mean square error(RMSE) were both less 0.20. The crack area coefficient of determination of different farmland types between the measured values and theoretical values of the distribution function were both larger than 0.90, while for the crack length were both larger than 0.94. And their RMSE were both less than 0.12. This research indicated that normal distribution is appropriate to depict crack morphology on soil surface through, which is feasible to study the formation mechanism of soil crack and the effect of different crack shapes on soil preferential flow.