Wheat straw anticorrosion analysis based on pore area ratio and the effect of straw on the shear strength of silty soil
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摘要:
粉土性能不良，需改良后才能在高速公路路基中使用；麦秸秆环保可再生，掺入粉土会起到加筋作用，但自身易被水腐蚀，需防腐后才能使用。本文从孔隙面积比出发，分析聚乙烯醇对秸秆的防腐机理和防腐效果，通过抗拉强度试验分析防腐对秸秆抗拉强度的影响；通过直剪试验分析秸秆对粉土抗剪强度的影响。结果表明：聚乙烯醇通过自身防腐性能的发挥、填充麦秸秆孔隙减小吸水通路、在秸秆表面形成保护膜阻隔水分进入来实现防腐，孔隙面积比越小防腐效果越好；试验范围内，麦秸秆的防腐最佳浸泡时间为4 d，防腐剂最佳溶液浓度为10%，此时秸秆孔隙面积比最小，且防腐耗时最短，或经济最优。麦秸秆长度对孔隙面积比的影响主要在4 d内，与最终孔隙面积比关系不大。防腐麦秸秆抗拉强度提高。秸秆加筋土的黏聚力随秸秆掺量、麦秸秆长度的增加先增大后减小，最优掺量范围为0.4%～0.6%，最优秸秆长度为15 mm；内摩擦角随着秸秆掺量的增加略有增加，但增幅很小，不同长度下无明显规律。
Abstract:Silty soil is of poor performance and is needed to improve before it can be used in highway subgrades. Wheat straw is environmentally friendly and renewable. When mixed with silty soil, wheat straw can play a reinforcing role, but it is easily corroded by water and can be used after corrosion protection. Based on the pore area ratio, this paper analyzes the anticorrosion mechanism and anticorrosion effect of polyvinyl alcohol on straw, the effect of anticorrosion on the tensile strength through the tensile strength test and the effect of straw on the shear strength of silty soil through the direct shear test. The results show that polyvinyl alcohol exerts its own anti-corrosion performance, fills the straw pores to reduce water absorption channels, and forms a protective film on the straw surface to block water from entering to achieve anti-corrosion. The smaller the pore area ratio, the better the anti-corrosion effect. The best soaking time for straw preservative is 4 days, and the best solution concentration for preservatives is 10%. At this time, the straw pore area ratio is the smallest, and the time for preserving is the shortest or economically optimal. The effect of the length of wheat straw on the pore area ratio is mainly within 4 days, and is not related to the final pore area ratio. The tensile strength of the anticorrosive wheat straw is increased. The cohesion of straw reinforced soil increases first and then decreases with the increase of straw content and wheat straw length. The optimal content range from 0.4% to 0.6%, and the optimal straw length is 15 mm. The internal friction angle increases slightly with the increasing straw content, but the increase is very small, and there is no obvious pattern under different lengths.
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Key words:
- wheat straw /
- pore area ratio /
- binary method /
- anticorrosion mechanism /
- antiseptic effect /
- shear strength
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表 1 颗粒粒径组成
Table 1. Particle size composition
粒径/mm 5～2 2～0.5 0.5～0.25 0.25～0.075 0.075～0.005 ≤0.005 含量/% 1.74 1.86 1.21 2.12 92.88 0.19 
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表 2 基于材料和时间因素的麦秸秆孔隙面积比测定
Table 2. Wheat straw pore area ratio determination based on material and time factors
麦秸秆长度l/mm 浸泡麦秸秆质量m/g 取用麦秸秆根数n 防腐剂溶液浓度c/% 溶液体积v/mL 浸泡时间t/d 20 10 5 4,6,8,10,12 900 1,2,3,4,5,6,7 10,15,20,30 10 5 试验测得的最佳浓度 900 1,2,3,4,5,6,7 说明：为减小误差，对浸泡聚乙烯醇溶液中的麦秸秆，在规定浸泡天数后每次均取出5根，在40 ℃的温度下烘干10 h去除少量水分的影响后，对5根分别进行孔隙面积比测定并取均值，以下秸秆孔隙面积比的测定也采用了同样的方法。
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表 3 不同浓度下公式(1)拟合后的参数值
Table 3. Parameter values at different concentrations
浓度参数 4% 6% 8% 10% 12% a −0.2427 −0.32263 −0.35864 −0.54855 −0.39861 b 1.97152 2.16722 2.39111 2.75855 2.79711 R2 0.99935 0.99895 0.99891 0.99794 0.9989
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表 4 不同长度下0～4 d范围内的曲线拟合参数
Table 4. Curve fitting parameters in the range of 0 to 4 days under different lengths
长度参数/mm 10 15 20 30 p 4.08234 4.11608 4.14074 4.18001 q −0.13241 −0.13569 −0.13679 −0.14072 R2 0.84911 0.92447 0.96535 0.99782
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