FLAC^(3D)中锚杆剪切破断失效的实现及应用

Implementation of shear broken failure of bolts in FLAC^(3D) and its application

为解决FLAC^(3D)中无法实现锚杆剪切破断失效的问题,基于PILE结构单元提出锚杆剪切破断判据Fs(i)≥Fsmax(i),采用Fish编程语言二次开发,建立PILE结构单元杆体修正力学模型,并嵌入到FLAC^(3D)主程序中。分别采用PILE单元杆体原模型和修正力学模型,进行杆体剪切实验和煤岩交界面滑移情况下的锚杆支护实验对比分析,结果表明:(1)修正模型杆体剪切荷载–位移曲线呈现出剪切破断失效的特性,达到了以剪力为判据的定量破断,且破断部位结构单元剪力和轴力在发生剪切破断后均突变为零,实现了FLAC^(3D)主程序中锚杆剪切破坏。(2)采用修正模型的锚杆支护方案中,煤岩交界面附近杆体发生剪切破断,且煤–底板交界面附近杆体破断先于煤—顶板交界面附近杆体;煤岩交界面最大滑移量比原模型大17.5 mm,结果更接近实际。(3)PILE修正单元剪切破断失效的实现扩展了FLAC^(3D)的应用范围。

The shear broken failure of bolts cannot usually be simulated with the FLAC^3D. A broken criterion Fs（i）≥Fsmax（i） was thus proposed based on the PILE element. The modified mechanical model of PILE element was established and embedded into FLAC^3D. The direct shear tests of bolts and the bolt supporting tests of roadway with coal-rock interface slippage were simulated respectively with original and modified mechanical model of PILE element. The shear load-displacement curve with the modified model presented the shear broken failure characteristics, and the quantitative broken effect was achieved through the shear force judgement. The shear and axial forces of the failed elements of the bolts dropped to zero when the shear broken failure occurred, consequently the shear broken failure of bolt was realized in FLAC^3D. In the bolt support with the modified model, the shear broken failure occurred at the bolts around the coal-rock interface, and the bolts at the coal-floor interface failed earlier than those at the coal-roof interface. The greatest calculated displacement at the coal-rock interface with the modified model was 17.5 mm larger than that with the original model, and the result was more realistic. Overall, the range of application of FLAC^3D was extended with the implementation of shear broken failure of PILE element with the modified model.