均质土坝管涌溃决实验渗流分析

Experimental Seepage Analysis of Piping Break in Homogeneous Earth Dam

管涌渗漏破坏是导致土石坝溃决的主要原因之一,通过模型实验开展土石坝管涌过程渗流场变化研究,对土石坝安全预测预警具有重要意义。采用预设管涌通道模拟管涌渗漏的方式,建立了室内小尺寸均质土坝管涌溃决模型;通过布置小量程渗压计,获取土坝模型的渗流场数据,对土坝模型从蓄水到渗透破坏再到溃决全过程的渗流场变化进行了深入分析研究。分析发现,在蓄水阶段,相同轴距的管涌断面测点渗流压力小于非管涌断面测点的测值,但测值达到峰值的时间早于非管涌断面测点;在溃决阶段(出现明流和形成溃口阶段),坝体内渗流压力出现骤降,且越靠近管涌断面渗流压力骤降时间越早、骤降幅度也越大。该认识,对于土石坝管涌渗漏破坏预测预警提供借鉴。

The seepage failure of piping is one of the main reasons contributing to the break of earth-rock dam.It is of great significance to study the change of seepage field in the piping process of earth-rock dam by model experiment.By using the method of simulating piping leakage with preset piping passage,a piping break-out model of scale indoor homogeneous earth dam is established,and the seepage field data of the earth dam model are obtained by arranging a small-range percolator,the variation of seepage field in the whole process of earth dam model from impoundment to seepage failure to break is deeply analyzed and studied.It is found that,during the storage stage,the seepage pressure at the same axial distance is lower than that at the non-piping section,but the peak time is earlier than that at the non-piping section.During the burst stage(open flow and breach formation stage),the seepage pressure in the dam body drops suddenly,and the closer to the piping section,the earlier the time and the larger the magnitude of the pressure drop.This knowledge can be used for reference in the prediction and early warning of piping failure of earth-rock dams.