Study on Holmquist-Johnson-Cook Constitutive Model and Numerical Simulation of Red Sandstone Based on Static and Dynamic Mechanical Tests
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摘要: 岩石材料被广泛应用于防护工程和各种隧道等民用工程结构中,其动态力学性能研究具有重要意义。本文以山东济南某石矿的红砂岩为研究对象,利用三轴试验机和分离式霍普金森杆装置分别开展不同围压下和不同应变率下红砂岩的力学特性研究,并基于动静态力学试验对红砂岩的Holmquist-Johnson-Cook(HJC)本构模型的参数进行确定。采用已经确定的红砂岩的HJC本构模型的参数,建立了SHPB动态压缩试验的有限元模型对参数进行验证。结果表明:红砂岩在围压环境下,内部裂纹的扩展方向和程度受到限制,使得裂纹难以快速贯通,从而峰值应力随着静水压力和的增加而增加;红砂岩在不同气压的加载下,存在明显率效应现象,动态抗压和劈拉强度与平均应变率呈现正相关,通过抗压强度因子(DIFc)和抗拉强度因子(DIFl)的研究分析,动态拉伸峰值应力的率效应现象更为明显;确定的HJC本构模型参数在LS-DYAN中可以较好地模拟红砂岩在动态冲击的损伤失效过程,在在未达到最大峰值应力时,数值模拟结果与试验的结果应力-应变曲线基本一致。本文确定的致密、高强度的红砂岩参数可为红砂岩的动态力学性能的研究和工程应用提供参考。
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Abstract: Rock materials are widely used in protective engineering and various civil engineering structures such as tunnels, and the research on their dynamic mechanical properties is of great significance. In this paper, red sandstone from a stone mine in Jinan, Shandong Province was taken as the research object. Triaxial testing machines and split Hopkinson pressure bar (SHPB) devices were used to study the mechanical properties of red sandstone under different confining pressures and strain rates, respectively. Based on the static and dynamic mechanical tests, the parameters of the Holmquist-Johnson-Cook (HJC) constitutive model for red sandstone were calibrated. Using the calibrated parameters of the HJC constitutive model for red sandstone, a finite element model of the SHPB dynamic compression test was established to verify the parameters. The results show that: Under the confining pressure environment, the propagation direction and extent of internal cracks in red sandstone are restricted, making it difficult for cracks to penetrate rapidly. Thus, the peak stress increases with the increase of hydrostatic pressure. Under loading with different air pressures, red sandstone exhibits an obvious rate effect. The dynamic compressive and splitting tensile strengths are positively correlated with the average strain rate. Through the research and analysis of the dynamic increase factor for compressive strength (DIFc) and dynamic increase factor for tensile strength (DIFt), the rate effect of the dynamic tensile peak stress is more significant. The calibrated HJC constitutive model parameters can well simulate the damage and failure process of red sandstone under dynamic impact in LS-DYNA. Before reaching the maximum peak stress, the stress-strain curves from the numerical simulation results are basically consistent with those from the test results. The calibrated parameters for dense and high-strength red sandstone in this paper can provide a reference for the research on the dynamic mechanical properties of red sandstone and its engineering applications. -
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