基于自主研发的砂层淤堵装置系统分别研究渗流方向和流体速度改变时大肠杆菌的“沉积-脱离”特性。试验结果表明：1）3种不同流速下大肠杆菌堵塞呈马鞍状,浓度变化值先增加后减小,回调后再减小。其中,卡喉处的大肠杆菌阻塞具有一定的“依赖性”,影响回灌的效率;2）在改变渗流方向并增大流速后,大肠杆菌“沉积-脱离”的动态平衡被打破,大肠杆菌的浓度值降低,原本沉积在孔隙内的大肠杆菌在外力驱动下发生运移。通过监测出口端液样发现浓度值有较大幅度的增加。结合工程实践,若采用回扬的方式处理大肠杆菌阻塞的井周,过长的清洗时间可能会产生新的堵塞物,反而无法达到彻底清洗井体的要求,因此需要控制回扬的合理时间。
Abstract
During the process of groundwater source heat pump recharge, microbial blockage represented by Escherichia coli is one of the important causes of ground subsidence, and studying its blockage characteristics is of great practical significance. We studied the “sedimentation detachment” characteristics of Escherichia coli when the direction of seepage and fluid velocity changed using a self-developed sand layer clogging device. The experimental results showed that： 1） Escherichia coli blockage exhibited a saddle shape under three different flow rates, with concentration changes increasing first and then decreasing, and then decreasing again after a correction. Among them, the blockage of Escherichia coli at the throat has a certain degree of dependence, which affects the efficiency of reinjection; 2） After changing the direction of seepage and increasing the flow rate, the dynamic balance of “sedimentation detachment” of Escherichia coli is disrupted, and the concentration of Escherichia coli decreases. The Escherichia coli that originally deposited in the pores are driven to migrate by external forces. By monitoring the liquid sample at the outlet, it was found that there was a significant increase in concentration values. Based on engineering practice, if the method of backflushing is used to treat the wellbore blocked by Escherichia coli, excessive cleaning time may cause new blockages, which may not meet the requirements of thorough cleaning of the wellbore. Therefore, it is necessary to control the reasonable time of backflushing.
关键词
大肠杆菌 /
水源热泵 /
沉积-脱离 /
砂砾 /
堵塞 /
微生物
Key words
Escherichia coli /
water source heat pump /
sedimentation detachment /
sand and gravel /
clogging /
microorganism
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基金
岩土力学与工程安全全国重点实验室基金（SKLGGES-024038）
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