真空加载方式对排水板滤膜淤堵影响试验研究
Experimental study on effects of vacuum loading modes on clogging of drainage board filtration membranes
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摘要: 塑料排水板滤膜的淤堵直接影响到真空预压排水固结法加固新近吹填淤泥的效果,而真空荷载加载方式是引起排水板滤膜淤堵的主要原因之一。通过室内模型试验,采用5种不同等效直径的排水板滤膜并通过控制不同的真空加载方式加固新近吹填淤泥。试验过程中对泥面沉降、排水板和土中不同深度的真空度进行监测,试验结束后测试排水板滤膜的渗透系数。试验结果表明:真空荷载不分级或者分级梯度太大,对真空预压排水固结法加固新近淤泥效果较差,排水板滤膜容易产生淤堵;排水板滤膜的等效孔径越小其淤堵情况越严重。排水板滤膜发生淤堵后其渗透系数将降低,对土体的排水固结产生不利的影响。作者建议:在真空预压处理新近吹填淤泥的工程实践中,宜选用较大的排水板滤膜等效孔,真空荷载宜采用分级加载方式,且每级真空梯度不宜过大。Abstract: The clogging of drainage board filtration membranes directly affects the effects of newly-dredged mud reinforced by the vacuum preloading drainage consolidation method, and the vacuum loading mode is one of the main reasons that cause clogging of drainage board filtration membranes. The drainage board filtration membranes with 5 kinds of different equivalent diameters are used to reinforce newly-dredged mud by controlling vacuum loading modes in laboratory. The surface settlement and vacuum degree at different depths of drainage board and soil are monitored during the tests, and the permeability of drainage board filtration membranes are tested after tests. The results show that for the vacuum load without gradient or with large gradient, the effects of vacuum preloading drainage consolidation method to reinforce newly-dredged mud are poor, and drainage board filtration membranes are easily clogged. The smaller the equivalent diameter of drainage board filtration membrane the more severe the clogging. The permeability of drainage board filtration membranes decreases after clogging that causes unfavorable effects on soil drainage consolidation. It is suggested that the equivalent diameter of drainage board filtration membranes should be larger, the vacuum load should be graded, and each vacuum load gradient shouldn’t be too large in engineering practice by using the vacuum preloading method to treat newly-dredged mud.