高地应力条件下隧道多力学特性锚杆模型及应用研究

Modeling and Application of Multi-Mechanical Characteristics of Anchors in Tunnels Under High Geostress Conditions

为解决FLAC3D中Cable模型无法模拟锚杆(索)断裂失效,因而难以合理分析复杂地质条件下围岩稳定性的问题,采用数值计算手段对锚杆模型进行改进,提出锚杆(索)的失效判据,基于FISH语言修正Cable模型法向及锚固剂轴向本构关系,并将算法嵌入到运行程序中。结合Link模型构建多力学特性锚杆模型(MMC模型),并通过开展锚杆拉拔及模拟试验,对MMC模型进行验证。以月直山隧道工程为背景,构建隧道支护算例,对比Cable模型及MMC模型在工程模拟分析中的应用效果。结果表明:1)修正后的锚杆及锚固剂轴向本构模型包含破坏失效阶段,符合锚杆实际力学行为;2)锚杆拉拔试验模拟结果和真实试验结果接近,最大误差为2.9%,说明MMC模型能够合理模拟真实锚杆的受力及失效破坏特征;3)MMC模型在工程模拟中能直观地展现破断失效位置,且能够模拟锚固系统失效,而Cable模型在锚杆达到破坏条件后仍持续为围岩提供支护力,计算结果与实际存在较大偏差;4)MMC模型扩大了FLAC3D的应用范围及适用性,提高了锚杆支护的模拟能力。

The inability of the Cable model in FLAC3D to simulate anchor failure poses challenges in analyzing the stability of the surrounding rock under complex geological conditions.To address this limitation,the author enhances the Cable model using numerical methods and proposes a failure criterion for anchors.The constitutive relationship between the normal of the Cable model and the axis of anchorage is modified using the FISH language and the algorithm is embedded in the calculation program.Additionally,a multi-mechanical characteristics(MMC)model for anchors based on the link model is constructed.Furthermore,this model is validated through anchor tension tests and simulations.Finally,a case study is conducted on the Yuezhishan tunnel to analyze the applicability of the Cable and MMC models in project simulations.The results demonstrate the following:(1)The modified constitutive model encompasses the damage and failure stages,aligning the actual mechanical behavior of the anchors.(2)The anchor tension test simulation results closely match the real test results,with a maximum error of 2.9%,indicating the feasibility of the MMC model in simulating the anchor force and failure characteristics.(3)The MMC model can visually depict the location of anchor fracture and failure in engineering simulations and simulate anchor system failure.In contrast,the Cable model continues to support the surrounding rock after anchor failure and exhibits substantial errors.(4)The MMC model expands the application range and improves FLAC3D and simulation capability,thereby enhancing the applicability of the Cable model.