膨胀土渠坡往往因吸湿膨胀而发生浅层失稳,上覆压重换填水泥改性土成为处理浅层失稳的常用手段。以引江济淮工程弱膨胀土为研究对象,采用GDS三轴仪开展初始含水率为20%,压实度为96%的弱膨胀三轴膨胀试验,获得体应变和吸湿终了含水率随平均主应力变化关系式,建立了考虑含水率增量的三轴膨胀模型并探讨其工程应用,分析了引江济淮弱膨胀土渠坡稳定性及处理措施。研究结果表明:渠坡浅层吸湿膨胀引起一定深度范围内的土体发生非均匀膨胀变形是引起边坡失稳的主要因素。对于弱膨胀土低渠坡段(深度H≤8.7 m),采用0.3 m的压重荷载即可保障工程运行期安全。研究成果为优化工程设计、节省工程投资提供理论和设计依据。

Seepage-induced softening often leads to shallow instability in canal slopes composed of expansive soil. Overburden replacement with cement-modified soil has emerged as a commonly employed method to address this issue. This study focuses on the weak expansive soil along the route of the Yangtze-to-Huaihe Water Diversion Project. Using the GDS triaxial apparatus, we conducted triaxial weak expansion tests on the soil with an initial moisture content of 20% and a compactness of 96%. By examining the variations of volumetric strain and final moisture content with average principal stress, we established a triaxial expansion model that accounts for water content increment and discussed the model’s potential engineering applications. Furthermore, we analyzed the stability of the canal slope and proposed treatment measures. Results indicate that the non-uniform expansion deformation within a certain depth range caused by the shallow expansion of canal slope is the primary factor contributing to slope instability. For low channel slope sections comprised of weak expansive soil (H≤8.7 m), a compressive load of 0.3 m ensures project safety during the operation. The research finding offers a theoretical and design foundation for optimizing engineering design and reducing project costs.