Investigation of deformation characteristics of gate and earth–rock dam systems under deep overburden conditions

Gate and earth-rock dam systems are the preferred dam types for river sections under deep overburden conditions, low head, and high flow rates. This study established a three-dimensional finite element model incorporating all main structures of the gate-dam earth-rock dam system based on octree discretization technology. The stress-strain characteristics of this model were analyzed using the FEM-SBFEM coupling algorithm. The results show: (1) Structural stiffness, load transmission, dam volume, and overburden thickness account for the spatial non-uniformity in dam deformation, with vertical settlement in the earth-rock dam surpassing that of the gate dam by 28.1%. (2) Larger displacement occurs at the joints on both sides of the gate dam, while the central section exhibits relatively coordinated deformation. (3) A tensile stress zone with a maximum tensile stress of 2.6 MPa formed at the top of the cutoff wall due to bending deformation caused by inadequate deformation coordination between the cutoff wall and overburden. (4) The underground continuous walls exhibit uneven settlement patterns influenced by the earth-rock dam and gravity retaining walls, with tensile stress zones forming at both the top and bottom. This study effectively identified the mutual interactions and spatial deformation characteristics among components within the gate and earth-rock dam systems, locating vulnerable zones and providing basis for engineering design optimization. Additionally, the octree discretization technology and FEM-SBFEM coupling algorithm used in this study provide a reference for the numerical analysis of engineering problems with complex structures, huge computational domains, and strong nonlinearity.