基于Geo-studio心墙内高渗透区渗透特性研究

Research on permeability characteristics of high permeability zone in core wall based on Geo-studio

黏土心墙土石坝是我国应用最广泛坝型之一,其优点是适应地基变形能力较强、对地质条件要求较低、就地取材、造价低等。土石坝因自身构造特点存在渗流问题,渗透破坏是诱发土石坝失稳破坏的主要原因。心墙作为防渗体会因质量问题或施工不当等易出现高渗透区域,促使坝体发生渗透破坏,威胁坝体安全。以黑龙江省通河县二甲沟水库的黏土心墙土石坝为研究对象,采用二维有限元数值模拟技术和大数据统计分析方法,研究高渗透区域心墙对土石坝渗流场的影响。结果表明,高渗透区域显著提高坝体渗漏速率及渗漏量,提高心墙出逸点高程,增加局部孔隙水压力,影响心墙右侧(下游)渗流场。随着高渗透区域位置升高,坝体渗漏量逐步减少,心墙出逸点高程逐渐降低,孔隙水压力升高区域逐渐扩大,加剧对单宽渗漏量及心墙出逸点高程影响。高渗透区位置处于距坝基2、7、12和17 m时,引发区域内孔压偏高18%、50%、60%以及90%以上。当高渗透区域渗透系数增加时,位于中位高渗透区域的土体孔隙水压力偏高区域有缩小趋势。研究结果可为未来依据大坝监测数据作渗流反演分析及动态安全监控和评估提供参考,保证大坝在整个生命周期中具有连续性控制,提高坝体安全性。

Clay core wall earth-rock dam is one of the most widely used types of dams in China.It has advantages such as strong adaptability to foundation deformation,low requirements for geological conditions,on-site material sourcing,and low cost.However,due to its structural characteristics,the rockfill dam is prone to seepage problems,and seepage failure is the main cause of instability and damage.The core wall,as an impermeable barrier,may have high permeability areas due to quality issues or improper construction methods.These high permeability areas can lead to seepage failure in the dam body and pose a threat to dam safety.Taking a clay core rockfill dam in a certain location in Heilongjiang Province as a research model,two dimensional finite element numerical simulation technology and big data statistical analysis methods were used to study the influence of high permeability areas in the core wall on the seepage field of the rockfill dam.The results showed that high permeability areas significantly increased leakage rate and volume of water through the dam body,raised the elevation of flow outlet points from the core wall,and increased local pore water pressure affecting the downstream seepage field.As the position of high permeability areas increased,leakage volume gradually decreased while flow outlet point elevation from the core wall gradually lowered.At the same time,there was an increase in pore water pressure area affecting both single-width leakage volume and flow outlet point elevation from the core wall.When the position of high permeability areas was at a distance of 2,7,12 and 17 m from the dam base,respectively,the pore pressure in that area was elevated by about 18%,50%,60%or more than 90%.When the permeability coefficient of highlypermeable area increased,the area with elevated pore water pressure in the intermediate-highlypermeable area tended to shrink.The research results could be used for seepage inversion analysis and dynamic safety monitoring and evaluation based on dam monitoring data in the future,so as to ensure the continuity of dam control in the whole life cycle and improve the safety of dam.