超疏水材料改性粗粒土垫层防排渗水试验研究

Experimental Study on Anti-drainage Water of Coarse Soil Cushion Modified by Superhydrophobic Material

市政道路中央生态滤沟是海绵城市建设中改善城市内涝、实现雨水净化积存与植被绿化的重要设施.生态滤沟植土雨季渗透、旱季保持一定水位是实现其功能的关键,然而当前设计的结构较难实现调蓄功能,影响其功能的发挥.为此,选取超疏水材料改性粗粒土垫层,通过微结构参数测试与室内非饱和渗透试验论证改性粗粒土垫层的防排渗水调蓄功能.结果表明:超疏水材料改性后的粗粒土固液接触角为134.2°,比改性前提高了22.4%;所设计的改性垫层入渗试验中土柱累积入渗量随入渗时间表现为“初始短暂缓慢增长段—陡增段—趋稳不变段”的三阶段特征.最终垫层上部液面高度可维持14.4 cm,具备生态滤沟要求在旱季维持一定水头的防渗能力;相同疏水垫层和入渗条件下,垫层土样疏水性越强,孔径越小,垫层渗流趋稳所能承受的静水压力越大;超景深电镜观测表明超疏水材料在粗粒土表面包裹性良好,受渗水影响较小.该垫层具备稳定的防排渗水调蓄功能,研究结果对海绵城市与水利工程建设具有重要的理论与实际意义.

The central biological filter of municipal roads is an important facility to improve urban waterlogging,realize rainwater purification,rainwater accumulation and vegetation greening in sponge city construction.The key to the function of the ecological filter ditch is that the soil can be penetrated in the rainy season and the water level can be maintained in the dry season.However,the current design structure is difficult to realize the storage function,which influences its use effect.For this reason,the coarse-grained soil cushion modified by superhydrophobic material was selected to demonstrate its water regulation and storage function by means of microstructural parameters test and laboratory test of unsaturated soil on permeability.The results show that the measured solid-liquid contact angle of the coarse soil is 134.2°after the modification of the superhydrophobic material,which is 22.4%higher than that of the ordinary coarse soil.In the designed modified cushion infiltration test,the cumulative infiltration amount of the soil column shows a three-stage characteristic with the infiltration time of“initial short and slow growth stage-abrupt increase stage-stable and constant stage”.And it could maintain 14.4 cm in the end,with the anti-seepage ability of a certain water head required by ecological filtration ditch in the dry season.Under the same hydrophobic cushion and infiltration conditions,the stronger the hydrophobicity of the cushion soil sample is,the smaller the pore diameter is,and the greater the hydrostatic pressure the cushion seepage tends to be stable.The superhydrophobic materials were well coated on the surface of coarse soil and were less affected by water seepage.The cushion has a stable function of water storage,anti-drainage and seepage.The research results have important theoretical and practical significance for sponge city and water conservancy project construction.