管道回填土粒径级配对土体侵蚀影响试验研究

为了深入探究排水管道回填土颗粒粒径与级配对土体侵蚀的影响,文章搭建长0.5 m、宽0.2 m、高0.7 m的排水管道沟槽试验模型,研究干燥状态下4种单一粒径均质砂层和3种不连续级配砂层的侵蚀敏感性。试验结果表明,对于均质砂层,随着颗粒粒径减小,依次出现直接阻塞、不完全侵蚀、完全侵蚀3种不同侵蚀类型,且不同侵蚀类型可以用临界孔口颗粒尺寸比来划分。通过对临界颗粒粒径砂层的50次重复试验,得出发生3种不同侵蚀类型的概率分别为0.38、0.26、0.36。对于不连续级配砂层,侵蚀量与细颗粒质量比呈正相关关系,和粗颗粒与细颗粒的粒径之比(反映粗颗粒粒径的作用)呈负相关关系。研究成果可为排水管道周围地面塌陷灾害防治及风险评估提供理论依据。

In order to explore the influence of particle size and gradation of backfill soil on soil erosion around sewers, a test model of sewer grooves with length of 0.5 m, width of 0.2 m and height of 0.7 m was built. The erosion sensitivity of four kinds of uniformly-graded sands and three kinds of gap-graded sands under dry conditions was studied. The experimental results show that for the homogeneous sands, with the decrease of particle size, there are three different erosion types, including clogging, incomplete erosion and complete erosion, and the different erosion types can be classified by the critical ratio of the size of the orifice to the diameter of the particles. The probability of three different erosion types is 0.38, 0.26 and 0.36, respectively, according to 50 repeated tests on the critical particle size sands. For gap-graded sands, the amount of erosion particles is positively correlated with the content of fine particles, and negatively correlated with the ratio of coarse particle size to fine particle size. The research results provide a theoretical basis for the prevention and risk assessment of ground collapse around sewers.