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在深海能源土、岩石风化等问题离散元模拟中,颗粒间胶结物的增减将对材料宏观力学特性有显著影响,因此需要建立考虑胶结厚度和宽度的胶结模型。针对离散元理论中粒间真实形状胶结物在粒间力作用下的刚度和强度确定问题,基于原始的Dvorkin理论,给出高精度的胶结力学响应理论解。求解中将位移函数对称化,提出一种修正位移试函数的方法,提高了二维颗粒微观胶结模型应力场的对称性和精度,经验证解答在定性和定量上符合有限元模拟结果。根据所得解答对胶结物几何参数进行了分析,讨论了胶结宽度和厚度对胶结刚度的影响,并给出了针对一般常见材料的刚度拟合公式。采用双剪统一强度理论分析了脆性和塑性胶结材料的初始破坏区位置,给出拉/压剪复合受力状态的强度包线。本文解答可方便快捷地获得胶结模型的大量力学响应信息,可作为试验数据的验证和补充,协助建立胶结物在复杂荷载作用下的破坏判据,进而建立完整的离散元胶结模型。
In the discrete element simulation of deep-sea energy sources such as soil weathering and rock weathering, the increase or decrease of cement content between particles will have a significant effect on the macroscopic mechanical properties of the material. Therefore, a cementing model considering the thickness and width of cementing should be established. According to the original Dvorkin theory, a high-precision solution to the cementation mechanics response theory is proposed to solve the problem of determining the stiffness and strength of the intergranular real cement under the effect of the intergrain force. In the solution, the displacement function is symmetrical. A method to correct the displacement test function is proposed, which improves the symmetry and accuracy of the stress field in two-dimensional particle microscopic cementing model. The validated answers satisfy the finite element simulation results qualitatively and quantitatively. Based on the results obtained, the geometrical parameters of the cement were analyzed. The influence of the cementation width and thickness on the cementation stiffness was discussed. The stiffness fitting formula for common materials was given. The dual-shear unified strength theory was used to analyze the location of the initial failure zone of the brittle and plastic cementitious materials and give the strength envelope of the composite stress state under tension / compression shear. In this paper, a large number of mechanics response information of cementing model can be obtained easily and quickly, which can be used as the verification and supplement of the experimental data to help establish the failure criteria of cement under complex loads and establish a complete discrete element cementing model.