管涌险情是堤防汛期的主要险情之一,开展管涌侵蚀过程及强度演变的研究具有重要意义。利用改进的管涌侵蚀试验装置,探究了在相同土样条件下不同围压应力(25 kPa、35 kPa、45 kPa)对散粒土管涌侵蚀水力特性、土体颗粒流失以及侵蚀后土体强度变化的影响规律。结果表明:(1)不同应力条件下,散粒土发生管涌侵蚀破坏的临界水力梯度随应力的增大而增大,渗流流速表现出了相反的发展趋势,随应力的增大而减小且曲线斜率也随应力的增大逐渐减小;(2)散粒土发生管涌侵蚀破坏的累计涌砂量和体积变化量均与土体所受应力呈负相关关系;(3)土体强度受侵蚀率的影响,随着侵蚀速率的加剧,土体强度呈下降趋势,不同应力条件下土体强度的下降趋势是大致相同且相差较小,对比说明改变外部的应力状态对土体强度的影响较小。
The risk of pipe surge is one of the main hazards in the flood season of embankments, and it is of great significance to conduct research on the erosion process and intensity evolution of pipe surge. The influence of different confining stresses (25 kPa, 35 kPa, 45 kPa) on the hydraulic characteristics, particle loss, and strength changes of granular soil caused by pipe surge erosion under the same soil sample conditions was investigated using an improved pipe surge erosion test device. The results show that: (1) Under different stress conditions, the critical hydraulic gradient for the occurrence of piping erosion and failure in granular soil increases with the increase of stress, while the seepage velocity shows the opposite development trend, decreasing with the increase of stress and the slope of the curve gradually decreasing with the increase of stress. (2)The cumulative sand discharge and volume change during piping erosion are negatively correlated with the applied confining pressure. (3) The strength of soil is affected by the erosion rate. As the erosion rate increases, the strength of soil shows a decreasing trend. The decreasing trend of soil strength under different stress conditions is roughly the same and the difference is small. Comparison shows that changing the external stress state has a relatively small impact on soil strength.
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