点源漏损砂土侵蚀成洞模型试验

Soil Erosion Model Test Caused by Pipeline Damage

岩土体侵蚀规律对水力管线漏损与地质环境耦合作用下道路塌陷灾变预警具有重要意义。基于持续性水土流失设计理念,研制了塌陷试验地下水环境模拟系统,开展了不同密实度砂土侵蚀成洞试验。揭示了砂土点源管线漏损侵蚀-成洞-塌陷的灾变演化过程:稳定渗流、缓慢侵蚀、快速发展。研究表明:砂土密实度越大颗粒间接触越紧密,砂土流失临界浸润线面积越大;点源漏损成洞特性与砂土密实度密切相关,松散时空洞总体呈现上宽下窄的敞口型,密实时地表塌陷宽度小于地质体内空洞最大宽度;砂土流失速率曲线总体呈类“驼峰”性,超过界限点时砂土流失率急剧增大,快速侵蚀垮塌。通过对比不同密实度的侵蚀量与最终侵蚀状态,得到密实度与水土流失的规律。

The law of rock and soil mass erosion is one kinds of great significance for the early warning of road collapse disasters under the coupling effect of hydraulic pipeline leakage and geological environment.The groundwater environment simulation system of collapse test was developed based on the design concept of continuous soil and water loss.The experiment of sand erosion into holes with different density was carried out in this regard.The evolution process of leakage erosion-cave-collapse of sand point source pipeline is re‐vealed:steady seepage,slow erosion and rapid development.The results show that the greater the density of sand,the closer the contact between particles,and the greater the critical infiltration line area of sand loss.The characteristics of point source leakage caving are closely related to the density of sand soil.The caving is generally open and narrow at the bottom when the sand is loose;the surface collapse width is smaller than the maximum width of the caving in the geological body when the sand is compact.The rate of sand loss curve generally shows a hump-like behavior,and the sand loss rate increases sharply when it exceeds the boundary point,then the erosion collapses quickly.The law of compactness and soil erosion was obtained by comparing the amount of erosion and the final erosion state of different compactness.