不同黏结长度锚杆拉拔承载特性研究

Investigation on the pull-out bearing characteristics of bolts with different bond lengths

黏结长度是影响锚杆承载性能的关键因素之一,研究不同黏结长度锚杆的拉拔承载特性对锚杆支护设计具有重要意义。为此,基于锚固界面的“三线性”黏结-滑移模型,采用FLAC3D数值软件研究了不同黏结长度锚杆的拉拔承载特性。研究结果表明:黏结长度会显著影响锚杆拉拔载荷-位移曲线的形态和发展过程,增大锚杆黏结长度能够提高其承载能力,提高锚杆抵抗失效的能力。随着黏结长度的增加,锚杆峰值拉拔载荷先快速增大后稳定增大,锚杆软化载荷和摩擦载荷先逐渐增大后保持不变,锚杆存在临界黏结长度。拉拔载荷作用下,锚杆轴力沿锚杆长度方向逐渐降低,峰值剪应力最先出现在锚杆加载端,并逐渐向锚杆自由端移动。随着黏结长度的增加,锚杆轴力作用范围增大,锚杆剪应力的不均匀性增加。研究结果可为锚杆支护设计提供有益参考。

Bond length is one of the key factors affecting the bearing performance of rock bolts.It is of great significance to study the pull-out bearing characteristics of bolts with different bond length for the design of bolt support.For this purpose,based on the''trilinear''bond-slip model of the anchoring interface,the FLAC3D numerical software was used to study the pull-out bearing characteristics of bolts with different bond length.The research results show that the bond length significantly affects the shape and development process of the pull-out load-displacement curve of a bolt.Increasing the bond length can improve the bearing capacity of the bolt and enhance its ability to resist failure.With the increase of the bond length,the peak pull-out load of the bolt first increases rapidly and then steadily.The softening load and friction load of the bolt increase first and then remain unchanged.There is a critical bond length of the bolt.Under the pull-out load,the axial force of the bolt gradually decreases along the length of the bolt,the peak shear stress first appears at the loading end of the bolt and gradually moves to the free end of the bolt.With the increase of the bond length,the range of the bolt axial force increases and so does the unevenness of the bolt shear stress.The research results may provide a useful reference for the design of bolt support.