秸秆长度对黑土力学特征的影响

发布时间：2018-03-31 07:40

本文选题：有机质　切入点：黏粒　出处：《南京林业大学学报(自然科学版)》2017年05期

【摘要】：【目的】研究了秸秆还田时不同长度秸秆对黑土力学特性的影响机制,为黑土压实与恢复、侵蚀与保护提供理论依据。【方法】试验于2016年6月以黑龙江省西北部的克山农场境内典型黑土区未经开垦(高有机质低黏粒含量)以及耕作40 a(低有机质高黏粒含量)的土壤为研究对象,在还田秸秆质量分数为1%、土壤含水量为20%,以及土壤容重为1.1 g/cm~3的条件下,采用室内固结和三轴剪切相结合的方法,通过压缩指数、回弹指数、黏聚力及内摩擦角的测定与分析,模拟研究了不同长度(1、5、15、25 mm和空白对照)小麦秸秆对黑土压缩、回弹及抗剪切行为的影响机制。【结果】模拟秸秆还田可以有效改善黑土力学特性,长期耕作的低有机质高黏粒含量的土壤在添加秸秆后抵抗剪切能力的增强效果最为显著。秸秆长度分别与压缩指数呈负相关,与回弹指数呈正相关,且添加15 mm长度秸秆的黑土压缩指数最低而回弹指数最高,即此时其抗压能力及压实后自然恢复能力最强。随着秸秆长度的增加,黑土的抗剪强度逐渐显著增强,但增幅逐渐减小。【结论】秸秆还田措施对黑土力学特征有显著的改善效果,且模拟试验结果的秸秆最佳长度为15 mm。
[Abstract]:[objective] to study the mechanism of the effect of straw of different length on the mechanical properties of black soil when straw was returned to the field, that is, the compaction and restoration of black soil. Erosion and conservation provide theoretical basis. [methods] the experiment was conducted in June 2016 with uncultivated (high organic matter and low clay content) and 40 years tillage (low organic matter and high clay content) in typical black soil areas of Keshan Farm in northwestern Heilongjiang Province. Content of soil, Under the condition that the straw content is 1, the soil moisture content is 20 and the soil bulk density is 1.1 g/cm~3, the compression index, springback index, cohesion force and internal friction angle are measured and analyzed by the method of indoor consolidation and triaxial shear. The effects of wheat straw on the compressive, springback and shear behavior of black soil were simulated and studied. [results] the mechanical properties of black soil were improved by simulating straw returning to the field. The soil with low organic matter and high clay content under long-term tillage had the most significant enhancement effect on shear resistance after adding straw. Straw length was negatively correlated with compression index and positively correlated with resilience index. The compression index of black soil with 15 mm straw was the lowest and the springback index was the highest, that is to say, the compressive capacity and natural recovery ability of black soil were the strongest after compaction. With the increase of straw length, the shear strength of black soil gradually increased significantly. [conclusion] Straw returning measures can significantly improve the mechanical characteristics of black soil, and the optimum length of straw is 15 mm.
【作者单位】：东北林业大学林学院;东北林业大学土木工程学院;
【基金】：国家自然科学基金项目(41302222,41271293)
【分类号】：S152.9

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