止水帷幕缝隙渗漏变化过程试验研究

由于施工工艺的原因,止水帷幕一般存在缝隙。在长期渗流的作用下,带缝隙的止水帷幕渗漏量如何发展需要进一步研究。因此,作者自行设计并制作了砂槽模型模拟带裂缝的止水帷幕,并开展了一系列的渗流试验。试验考虑了水力条件、砂样级配和缝隙尺度因素的影响。结果表明,在水头不变的情况下,各试验中均出现了渗漏量下降的现象,但水头升高则会破坏这一现象。缝隙渗漏量下降的实质是砂颗粒移动和聚集导致淤堵的产生,淤堵位置可能在上下游缝口、缝隙进出口或缝隙内。当砂样粒径较细时,缝隙渗漏量下降效果最为显著;当下游回填级配不稳定的砂样时,缝隙渗漏量下降效果不佳。

Laboratory study of leakage process for cut-off wall with crack

Generally, there are cracks in the cut-off wall because of the defects in construction craft. Therefore, it is necessary to further study the water interception capacity of the cut-off wall with cracks in the long term of seepage. The authors designed and made a sand box to simulate the cut-off wall with cracks, and carried out a series of seepage tests. Hydraulic conditions, gradation of soil specimens and crack size were considered in the tests. The results showed that,under the condition of constant head,the total flow rate of leakage decreased in each test, but the flow rate increased again when the head rose. The essence of the decrease of leaking flow rate is that the movement and aggregation of sand particles lead to the formation of clogging,which may be formed in the area near the inlet and outlet of the crack, or within the crack. When the particle size of sand is fine,the effect of leaking flow rate drop is most sig-nificant. However, when unstable sand is backfilled in the downstream, the effect of crack leakage reduc-tion is poor.