以引江济淮工程膨胀土边坡表层采用的水泥改性膨胀土换填土层为研究对象,为探究各因素和水平对狗牙根的发芽、生长状况和根系展布的影响规律,以4种添加剂(泥炭、保水剂、有机肥、土壤改良剂PAM)和压实度为5个因素,各取4个水平,开展了多指标多因素正交试验。采用发芽率、生长高度、覆盖度、根系入土深度和含根量5个指标对狗牙根生长效果进行综合评价。试验结果表明:影响狗牙根生长因素的重要性由高到低依次为有机肥、压实度、保水剂、泥炭、土壤改良剂(PAM)。有机肥和泥炭含量对狗牙根生长和土壤改良具有良好的促进作用,而土壤压实度越高,狗牙根生长越差;为确保狗牙根较好生长,压实度不宜过高,建议不超过86%。对于膨胀土边坡表层采用的水泥改性膨胀土换填土层,适合狗牙根生长的最优改良方案为:泥炭掺量取9%、保水剂掺量取0.05%、有机肥掺量取1.5%、土壤改良剂(PAM)掺量取0.05%,压实度控制为66%。研究结果对引江济淮工程膨胀土地区采用水泥改性膨胀土换填土层进行生态修复具有指导意义,分析和评价方法亦可为其他区域采用水泥改性膨胀土换填土层进行生态修复提供参考。

A multi-index and multi-factor orthogonal experiment was carried out to explore the influence of various factors and levels on the germination, growth and root distribution of bermudagrass planted in the surface cement-modified soil of expansive soil slope of the water diversion project from Yangtze River to Huaihe River. The orthogonal experiment was designed with five factors (peat content, water retention agent content, organic fertilizer content, PAM content, and degree of compaction) and four levels. The vegetation restoration effect was comprehensively evaluated by five indexes, namely, plant germination rate, growth height, coverage, root penetration depth, and root content. Results showed that the importance of the factors affecting plant growth was organic fertilizer content, degree of compaction, water retention agent, peat content, and PAM content in descending order. Content of fertilizer and peat has a good promoting effect on plant growth and soil improvement. The higher the soil compaction degree, the worse the plant growth; to ensure better plant growth, the compaction should not exceed 86%. For the expansive soil slopes of the Y003 segment of the water diversion project from Yangtze River to the Huaihe River, the optimal improvement plan for the growth of plant (bermudagrass) is: replacing the original surface expansive soil with cement-modified soil with 9% peat, 0.05% water retention agent, 1.5% organic fertilizer, 0.05%PAM, and compaction degree at 66%. The research finding is of guiding significance for the ecological restoration of cement-modified soil in the area of diversion project from the Yangtze River-to-Huaihe River. The analysis and evaluation methods can also be used as references for the ecological restoration of cement-modified soil in other regions.