低渗污染场地水力压裂强化修复药剂输运机制  

Mechanisms of amendment transport in low-permeability contaminated sitesenhanced by hydraulic fracturing

作　　者：陈贺[1] 冯世进[1,2] 郑奇腾 陈宏信 CHEN He;FENG Shijin;ZHENG Qiteng;CHEN Hongxin(Department of Geotechnical Engineering,Tongji University,Shanghai 200092,China;State Key Laboratory of Disaster Reduction in Civil Engineering,Tongji University,Shanghai 200092,China;Key Laboratory of Geotechnical and Underground Engineering of the Ministry of Education,Tongji University,Shanghai 200092,China)

机构地区：[1]同济大学地下建筑与工程系,上海200092 [2]同济大学土木工程防灾减灾全国重点实验室,上海200092 [3]同济大学岩土及地下工程教育部重点实验室,上海200092

出　　处：《环境工程学报》2024年第4期937-945,共9页Chinese Journal of Environmental Engineering

基　　金：国家重点研发计划资助项目(2020YFC1808104)。

摘　　要：由于低渗透污染场地较低的渗透特性极大限制了修复药剂的注入和运移,导致传统修复方法的治理效率低下。水力压裂作为强化传质的有效手段已得到广泛认可。因此结合注入-抽提技术,构建了低渗污染场地中考虑水力压裂的修复药剂强化输运数值模型。该模型考虑了修复药剂输运的对流、扩散、吸附和降解机制,研究了水力裂缝对低渗场地中修复药剂运移的强化作用。并基于地统计学方法生成随机渗透率场以研究异质性对修复药剂输运和分布的影响。结果表明,水力裂缝可通过形成优渗通道、强化压力传递等方式有效促进修复药剂的运移,相比于低渗场地,压裂场地中修复药剂的影响范围至少增大50%;场地的异质性会导致药剂浓度出现显著波动和局部浓度聚集,且波动程度随着异质性的增大而增强,因此造成弱异质性场地特定位置药剂缺失率在7.14%左右,而强异质性场地药剂缺失率高达28.57%。Due to the low permeability characteristics of contaminated clay sites,the injection and migration of amendments are significantly hindered,leading to a reduced efficiency of traditional remediation methods.Hydraulic fracturing,as an effective means of enhancing mass transfer,has been widely recognized.Hence,in conjunction with the injection-extraction technique,this study developed a numerical model for the enhanced transport of amendments in low-permeability contaminated sites by hydraulic fracturing that considers the convection,diffusion,adsorption,and degradation mechanisms and investigates the enhancing role of hydraulic fractures in the transport of amendments in low-permeability environments.Based on geostatistical methods,a random permeability field was generated to study the influence of heterogeneity on the transport and distribution of amendments.The results indicate that hydraulic fractures can effectively promote the migration of amendments by forming preferential flow paths and intensifying pressure transmission.Compared to lowpermeability sites,the influence range of amendments in fractured sites increased by at least 50%.The heterogeneity of the site leads to significant fluctuations in the concentration of amendments and localized concentration accumulations and the degree of fluctuation increases with the increase in heterogeneity.As a result,this results in a location-specific amendment missing rate of around 7.14%for weakly heterogeneous sites and up to 28.57%for strongly heterogeneous sites.

关 键 词：低渗场地 水力压裂 注入-抽提技术 强化输运 空间变异性 

分 类 号：X523[环境科学与工程—环境工程]