岩石-混凝土组合体单轴压缩力学与破坏特征数值模拟研究

Numerical study on the mechanical and failure characteristics of rock-concrete combination under uniaxial compression

目的为研究单轴压缩条件下混凝土组分骨料含量、强度等级、占比和界面倾角对岩石-混凝土组合体力学与破坏特征的影响,方法结合凸多边形随机骨料生成投放程序与RFPA2D分析系统,构建组合体数值模型并进行数值模拟。结果组合体的破坏类型可分为由混凝土组分破坏并延伸至花岗岩组分或两种组分及界面共同破坏引起的“两体Ⅰ型和Ⅱ型破坏”,由混凝土组分单独破坏或混凝土组分和界面共同破坏引起的“单体Ⅰ型和Ⅱ型破坏”。对界面处应力状态进行分析,从理论上解释了沿界面宏观裂纹的形成原因;组合体抗压强度接近混凝土的抗压强度,其值与混凝土组分强度等级正相关而与占比负相关;组合体弹性模量数值模拟结果与理论值吻合较好,且与骨料含量和强度等级正相关,与混凝土组分占比和界面倾角负相关;组合体泊松比与骨料含量和混凝土组分占比负相关,强度等级对其影响较小;组合体抗压强度和泊松比均随界面倾角的增加先减小后增加。结论构建了含骨料岩石-混凝土组合体数值模型,并运用RFPA2D分析系统对4种组合方式组合体进行数值模拟,可通过提高混凝土组分强度、降低混凝土组分占比与材料间的界面倾角提升组合体的力学特性。研究结果可为地下或坝体等工程的稳定性分析提供参考依据。

Objectives This study aims to investigate the effects of aggregate content,strength grade,propor⁃tion,and interface angle of concrete components on the mechanical properties and failure characteristics of rock-concrete composites under uniaxial compression conditions.Methods A numerical model of the composite body was constructed using a convex polygon random aggregate generation deployment program and the RFPA2D analysis system.Numerical simulations were conducted to analyze four types of composite specimens.Results The results show that the failure types of the composite can be classified into two catego⁃ries:two-body typeⅠandⅡfailures,caused by the failure of the concrete component extending to the granite component or the simultaneous failure of both components and the interface,and single-body typeⅠandⅡfailures,caused by the failure of the concrete component alone or the simultaneous failure of the concrete component and the interface.The stress state analysis at the interface provided a theoretical expla⁃nation for the formation of macro-cracks along the interface.The compressive strength of the composite was close to the uniaxial compressive strength of concrete.Its value was positively correlated with the strength grade of the concrete component and negatively correlated with the proportion.The numerical simulation re⁃sults of the elastic modulus of the composite were in good agreement with the theoretical values.They showed a positive correlation with the aggregate content and strength grade and a negative correlation with the proportion and interface inclination angle.The Poisson’s ratio of the composite was negatively corre⁃lated with the aggregate content and proportion,while the influence of the strength grade on it was relatively small.Additionally,both the compressive strength and Poisson’s ratio of the composite exhibited a decreasing-then-increasing trend with increasing interface inclination angle.Conclusions A numerical model of concrete-rock composite specimens containing aggregates was constructed,and numerical simula⁃tions were conducted on four types of composite specimens using the RFPA2D analysis system.The mechanical properties of the composite specimens can be enhanced by increasing the strength of concrete components,reducing the proportion of concrete,and decreasing the interface angle between materials.The results provide a basis for the stability analysis of underground or dam engineering.