落底式止水帷幕对地下径流的阻碍影响分析

Analysis on Influence of Bottom-falling Water-stop Curtain on Underground Runoff

截止到2012年,海绵城市的提出已有9年时间,然而中国城市内涝的问题依然严重,海绵城市的建设并未取得理想成绩。目前,海绵城市建设措施的研究方向多集中于解决地表问题,而对地下水的排渗与地下径流却鲜有关注。通过有限元COMSOL软件对落底式止水帷幕及其周边区域进行数值模拟计算,以选取面积内的瞬时总流量为指标,研究分析落底式止水帷幕对地下径流的阻碍作用,并在此基础上研究不同倒角对阻碍作用的影响,以找到降低阻碍作用的方法。研究表明,边长200 m的止水帷幕会对周围20000 m×4500 m范围内的地下水流动产生影响,在1000 m的范围内会对地下水产生较大的流量削减,造成局部地下水水位上升,使附近的海绵城市设施工作效率降低,不利于海绵城市的建设。对止水帷幕的4个角进行倒角可以降低其阻碍作用,其中对止水帷幕进行45°角的切角施工较简单,优化效果较好,是一种行之有效的低影响开发手段,可以促进海绵城市的建设。

As of 2012,sponge city has been put forward for nine years.However,the problem of urban waterlogging in China is still serious,and the construction of sponge city has not achieved ideal results.At present,the research direction of sponge city construction measures mostly focuses on solving surface problems,but little attention is paid to groundwater drainage and groundwater runoff.The numerical simulation calculation on the bottom-falling water-stop curtain and its surrounding area was carried out through the finite element software COMSOL.Taking the instantaneous total flow in the selected area as an index,the blocking effect of the bottom-falling water-stop curtain on underground runoff was studied and analyzed.On this basis,the influence of different chamfers on the blocking effect was studied,so as to find a method to reduce the blocking effect.The research shows that the water stop curtain with a side length of 200 m will affect the groundwater flow within the surrounding range of 20000 m×4500 m,and in the range of 1000 m,the groundwater flow will be greatly reduced,which will reduce the working efficiency of the facilities in the nearby sponge city,and is not conducive to the construction of sponge city.Chamfering the four corners of the water stop curtain can reduce its blocking effect,among which the 45°angle chamfering construction of the water-stop curtain is simpler and has better optimization effect,which is an effective method of low-impact development and can promote the construction of sponge city.