玉米秸秆防腐及其粉土加筋效果研究

EXPERIMENTAL STUDY ON ANTI-CORROSION OF CORN STRAW AND ITS EFFECT IN SILT IMPROVEMENT

粉土因具有黏聚力低、水稳性差的特点,在工程中的使用受限;玉米秸秆具有较高的抗拉强度,是一种性能良好、环保的天然纤维,将经过防腐处理后的玉米秸秆作为加筋材料纤维掺加到粉土中,是否会起到良好的加固效果,本文将就此展开研究。首先对玉米秸秆皮进行抗拉强度测试,选取抗拉强度较高的无茎节点秸秆皮作为试样;将该试样用卡松、双乙酸钠、聚乙烯醇3种防腐溶液进行浸泡,并对浸泡处理后的试样进行抗拉强度测试,结果表明浸泡过3种防腐剂的秸秆在浸泡水后抗拉强度均比天然秸秆有不同程度的提升,其中聚乙烯醇的防腐效果最好,浸泡12周后抗拉强度比天然秸秆高出约60%;对用聚乙烯醇浸泡后的试样进行显微镜拍照和称重测试,显示秸秆在浸泡3天后对聚乙烯醇的吸收达到饱和。将用聚乙烯醇防腐处理后的玉米秸秆纤维掺加到粉土中,制样进行三轴试验,发现玉米秸秆加筋对粉土强度的提高主要体现在黏聚力上,其增幅为素土试样的100%,改善了土体的水稳定性;其应力-应变曲线更倾向于应变-硬化,有别于素土的应变软化,破坏形态较为完整,有别于素土的斜截面破坏,这说明粉土加入玉米秸秆纤维后抵抗外界荷载的能力增强。

Due to the characteristics of low cohension and poor water stability,the silt using in the civil engineering is limited. Corn straw can have high tensile strength and is known as a good natural and enviromental protection fiber. This paper examines the reinforcement effect of the corn straw after preservation treatment in silt. It applies the antiseptic treatment to corn straw. It proposes a new concept of utilizing corn straw to reinforce soil. A series of tests are conducted to verify this idea. Fristly the tensile strength of corn straw is tested and the straw barks without stem node is selected to be samples because of its higher strength. Then the samples are soaked into the Kathan,Sodium diacetate and Polyvinyl alcohol solutions individually for some time. Their tensile strength are tested to compared their antiseptic ability. Test results show that the straw which soaked in the three antiseptic solutions and after waterlogged have higher tensile strength than that of natural straw. The antiseptic effect of polyvinyl alcohol is the best. The sample at 12 weeks after the treatment with polyvinyl alcohol has the tensile strength of about 160% of the nature straw. Microscope photographs and weighing test are carried out on the samplessoaked into the polyvinyl alcoho. The results show that the straw can reach saturation after three days of immersion.The corn straw antiseptically treated with polyvinyl alcohol is then added into the silt and the triaxial tests are tested for the compacted silt samples. The strength increasing of silt reinforced with corn straw is mainly embodied in the cohesion. The increase is about 100%as much as pure soil,which contribute to water stability of silt; the curves of stress-strain relationship of reinforced soil come to exhibit a hardening character,which is different to the softening character of pure soil. The failure mode of reinforced soil is comparatively complete,which is different to shear failure modes of pure soil. These kind of phenomena show that the ability of silt to resist the external load is improved by corn straw fiber.