重载铁路黄土路堑三联生态护坡入渗稳定性及应用研究

Infiltration Stability Analysis and Practical Application of Triple Ecological Protection for Loess Cutting Slope of the Heavy-haul Railway

传统黄土路堑边坡防护易出现潜蚀性冲刷破坏导致防护失效,故提出一种工程措施与植物群落有机结合的新型三联生态护坡。为研究降雨下黄土路堑三联生态护坡入渗特征、稳定性及防护措施效果,首先,通过GDS三轴仪开展黄土土水特征曲线及抗剪强度试验,并采用V-G模型对所测土-水特征曲线进行拟合;其次,采用MIDAS-GTS有限元软件建立黄土路堑三联生态护坡计算模型,分析其入渗特征及稳定性,并依托蒙华铁路工程生态护坡试验段,分析其施工工艺,考察其应用效果。研究表明:对于该地区非饱和黄土“土-水特征曲线”,采用V-G模型拟合效果较好,黏聚力随含水率增加下降幅度较多,降雨下三联生态防护边坡浅层孔压和饱和度增加速度明显,引起边坡的浅层稳定性减低,浅层2 m范围内影响最为明显,故建议锚杆长度不宜超3 m,护坡高度不宜超过12 m。经现场工程实践,验证了三联生态护坡具有良好的抗冲刷、稳定坡面性能,且景观效果较好。

Traditional loess cutting slope protection is prone to erosion, which leads to protection failure. The triple ecological protection is a new technology combining engineering measures and plant communities. In order to study the infiltration characteristics, stability and protective measures effect of triple ecological protection under rainfall for loess cutting slope, the loess soil water characteristic curve and shear strength tests were carried out firstly by GDS triaxial apparatus, and the V-G model was used to fit the soil-water characteristic curve. A numerical calculation model was established to analyze its infiltration characteristics and stability by MIDAS-GTS. Based on the experimental section of the Menghua railway project, the construction technologies and the implementation effects were investigated. The results show that the V-G model is a good fit for the soil-water characteristic curves of the unsaturated loess in this area, its shear strength decreases with the increase of water content, and the cohesion decreases greatly. The pore pressure and saturation of the shallow slope increase obviously under rainfall, which cause the stability of the shallow slope to decrease, and the influence is most obvious in the shallow layer of 2 m. The bolt length should not exceed 3 m, and the slope protection height should not exceed 12 m. The field engineering verifies that the triple ecological protections have strong performances for anti-erosion, stabilizing slope surface and landscape. The research results can provide references for ecological protection of the loess cutting slope.