地基变形诱发大面积混凝土结构断裂损伤的数值模拟研究

Numerical Simulation of Fracture Damage of Large Area Concrete Structure Induced by Foundation Deformation

针对软土地层地基变形可能引发大面积混凝土结构附加应力场及导致混凝土结构断裂损伤的问题,通过建立符合工程特性的数值模型,模拟典型地基变形形态,系统研究混凝土结构全寿命周期中地基差异沉降变形引起结构应力状态变化、裂缝形成与演化的基本规律。结果表明:地基变形将导致混凝土结构形成显著的附加应力场,其分布与地基变形特征参数密切相关且受变形曲率支配,曲率越大应力集中程度越高;结构损伤风险因素主要是拉应力超限引起的局部断裂损伤;混凝土结构断裂损伤的风险区域主要位于截面高度大、刚度突变区域;张拉应力与地基变形曲率半径呈负指数型关系,当地基变形曲率半径小于某一量值,结构局部张拉断裂损伤风险将急剧上升。结果对软土地层大面积混凝土结构工程抗渗设计具有借鉴意义。

Aiming at the problems that foundation deformation in soft soil stratum may cause additional stress field of large-area concrete structure and fracture damage of concrete structure, by establishing a numerical model in line with engineering characteristics and simulating typical foundation deformation patterns, the basic laws of structural stress state change, crack formation and evolution caused by foundation differential settlement deformation in the whole life cycle of concrete structures are systematically studied. The results show that the foundation deformation will lead to the formation of significant additional stress field in the concrete structure, and its distribution is closely related to the characteristic parameters of the foundation deformation and is dominated by the deformation curvature, the greater the curvature, the higher the stress concentration degree;the main risk factors of structural damage are local fracture damage caused by the excessive tensile stress;the risk area of fracture damage of concrete structure is mainly located in the area with large section height and sudden change of stiffness;the tension stress has a negative exponential relationship with the curvature radius of foundation deformation. When the curvature radius of foundation deformation is less than a certain value, the risk of local tension fracture damage will rise sharply. The results can be used as reference for the anti-seepage design of large-area concrete structure engineering in soft soil layer.