竖向阻隔墙中土工复合膨润土防水毯搭接区渗透系数测试与分析  

Test and analysis of hydraulic conductivity of geosynthetic clay liners overlap in vertical barrier wall

作　　者：詹良通[1,2] 丁兆华 谢世平 李育超[1,2] 何顺辉 ZHAN Liang-tong;DING Zhao-hua;XIE Shi-ping;LI Yu-chao;HE Shun-hui(Institute of Geotechnical Engineering,Zhejiang University,Hangzhou,Zhejiang 310058,China;Key Laboratory of Soft Soils and Geoenvironmental Engineering of Ministry of Education,Zhejiang University,Hangzhou,Zhejiang 310058,China;Tianjin Zhonglian Gelin Science and Technology Development Co.Ltd.,Tianjin 300387,China)

机构地区：[1]浙江大学岩土工程研究所,浙江杭州310058 [2]浙江大学软弱土与环境土工教育部重点实验室,浙江杭州310058 [3]天津中联格林科技发展有限公司,天津300387

出　　处：《岩土力学》2021年第9期2387-2394,2404,共9页Rock and Soil Mechanics

基　　金：国家重点研发计划(No.2018YFC1802300);苏州市民生科技项目—科技示范工程(No.SS201804-01)。

摘　　要：土工复合膨润土防水毯(geosynthetic clay liners,简称GCLs)在污染场地竖向阻隔墙中应用是一项新技术,通过防水毯相邻幅间搭接区域土工织物的绕渗控制是该技术关键点之一,目前尚缺乏可靠的试验数据支撑。研制了尺寸为1 200 mm×700 mm×700 mm的搭接渗透仪器,在1 m水头差下开展了5级压力(10、25、50、100、150 kPa)下的GCL搭接渗透试验,测量了含500mm搭接区的GCL渗流通量,探究了侧向压力和搭接区是否涂抹膨润土膏对等效渗透系数的影响。试验结果表明:(1)GCL搭接区在渗透初期存在明确的绕流现象,由于绕渗的存在,GCL搭接区域的等效渗透系数ko比完整GCL渗透系数大,搭接区未涂抹膨润土膏时,在低压力(p=10 kPa)作用下前者是后者的5.6倍。(2)搭接区域等效渗透系数随侧向压力增大而减小,在搭接区未涂抹膨润土膏和低压力(p=10 kPa)作用下,搭接区域等效渗透系数ko等于2.27×10^(-8) cm/s,当侧向压力达到100k Pa后,等效渗透系数ko降低至5.93×10^(-9)cm/s。(3)搭接区涂抹膨润土膏能有效提高防渗性能,在各级侧向压力下,GCL搭接区域等效渗透系数ko均低于未涂抹膨润土膏时的,且在高压力状态下(p=150k Pa),ko值降低至5.15×10^(-10) cm/s。Geosynthetic clay liners(GCLs) are newly used in combination with the vertical barrier wall in waste landfills. One of the critical points of this application is to control the preferential flow in the overlapping area of adjacent GCLs. However, there is still a lack of reliable data. This paper aimed to investigate the influence of the overburden pressure on the equivalent hydraulic conductivity(ko) of the overlapping area with bentonite pastes, to the reference base case in which no bentonite paste was presented. A penetration apparatus with internal dimensions of 1 200 mm×700 mm×700 mm(length×width×height) was presented. The 500 mm long GCL overlap was tested under a combination of the hydraulic head being 1 m and the overburden stress being 10, 25, 50, 100 and 150 kPa, respectively. It was found that: 1) The preferential flow around the overlapping area of GCLs occurred at the initial stage of penetration. The ko of the overlapping zone under an overburden pressure of 10 kPa was 5.6 times greater than that of the GCL due to the existing preferential flow. 2) The ko of the overlapping area decreased with an increase in the overburden pressure. The ko of the overlapping area subjected to a low overburden pressure of 10 kPa was equal to 2.27×10^(-8) cm/s, while it decreased to 5.93×10^(-9) cm/s when the overburden pressure reached to 100 kPa. 3) The permeability was significant reduced by the presence of bentonite pastes in the overlapping area. The ko of the GCL overlapping area was lower than that without the bentonite paste, and the value of ko reduced to 5.15×10^(-10) cm/s when the overburden pressure was as high as 150 kPa.

关 键 词：土工复合膨润土防水毯(GCL) 搭接 渗透系数 膨润土 竖向阻隔墙 

分 类 号：TU470[建筑科学—结构工程]