围绕引江济淮工程膨胀土地段河渠边坡水泥改性土换填层易碱化板结、植物难以生长和局部弱膨胀土渠坡 的简化处理等工程实际问题，以生态优先、技术创新为原则，采用现场试验、室内单元体测试和数值分析等手段， 开展系统的研究工作。研发一种改善水泥改性土种植效果的生态基材，提出一种新型膨胀土双层护坡结构，并研 究提出根据实际土层膨胀特性和含水状态进行弱膨胀土边坡的处理原则。现场中试和运用效果表明：研发的生 态基材能适应水泥改性土的种植需要，使边坡实现良好的绿化效果，双层护坡结构较好地实现了膨胀土边坡防止 降雨入渗和水分蒸发的双重防护要求；同时，还可利用砂土层的压重效果，抑制土层的膨胀变形。研究成果为引 江济淮的工程设计和后期运行管理提供了技术支撑，同时，也为膨胀土地段渠坡生态处治探寻了新的方向。

Total length of the Yangtze-to-Huaihe Water Transfer Project is 723 km, more than 100 km of the river section is distributed with weak and medium expansive soil, and the maximum excavation depth of the canal is 46 m. The stability of the expansive soil section is one of the key technical problems of the project. In the preliminary design stage, the treatment measures of over digging, replacing and filling cement-modified soil were proposed for the expanded land section, but some ecological and environmental problems were generated, such as the cement modified soil is easy to be alkali, and makes it difficult for plants to grow. Moreover, slope overcutting would produce a large amount of waste soil which is adverse to the ecological environment. Whether simplified treatment measures can be applied to some weak expansion channels with slope heights less than 10 m is a question that needs to be addressed.Under the principle of ecological priority and technological innovation, the researchers carried out systematic research work using field experiments, indoor unit tests, and numerical analysis. The ecological restoration scheme using surface cultivated soil and grass was put forward through field sampling tests and numerical analysis for the low river embankment in the weak expansive soil around Chaohu Lake. An ecological substrate was developed to solve the problems such as soil alkali plate and plant growth difficulty in the medium expansive cement-modified soil replacement layer. The field pilot test proved that the ecological substrate is a new kind of ecological slope planting material. An ecologically friendly expansive soil slope protection structure is proposed using unsaturated soil theory based on the characteristics of a large difference in permeability coefficient between sand and clay. This structure can better solve the dual protection requirements of expansive soil slopes to prevent rainfall infiltration and water evaporation. At the same time, it can also use the compression effect of the sand layer to restrain the expansion and deformation of soil layer.The field pilot test and application results show that the ecological substrate developed can adapt to the planting needs of cement-modified soil so that the slope can achieve a good greening effect. The double-layer slope protection structure can better solve the dual protection requirements of the expansive soil slope to prevent rainfall infiltration and water evaporation. The expansion and deformation of the soil layer can also be controlled by the compression effect of the sand layer. The research results provide technical support for the engineering design and late operation management of the project, effectively solving the technical problems related to the expansion land section of the project, and provide a basis for the design and optimization of related river slope. Together, breakthroughs have been made in the engineering application of unsaturated soil theory and the ecological treatment of expansive soil slopes.