基于颗粒离散元法的锚固节理剪切行为宏细观研究

为了研究锚固节理岩体的破坏特点及锚固机理,基于颗粒离散元法利用修正的锚杆双线性本构模型对有锚和无锚节理面在不同边界条件下进行了宏观研究,并对锚固节理试件内部颗粒之间接触力和颗粒旋转弧度等的演化过程进行了细观研究。研究结果表明:1压剪作用下锚固节理块体中处于拉伸状态的锚杆对节理面施加了一个附加的法向应力,从而提高了节理面的黏聚力;随着法向应力的增加,锚杆对节理面峰值剪切强度的贡献越来越小,在宏观上揭示了加锚节理岩体的锚固机理。2压剪荷载和边界位移约束共同作用下,锚固节理试件内部颗粒间接触力和颗粒自身位置不断演化并重新分布,在锚杆周围以及节理面凸起处产生较高的接触压力并在锚杆与节理面交叉处发生较大的颗粒旋转弧度,进而导致压致拉裂纹的产生以及颗粒旋转导致的剪切裂纹的萌生,从细观层面揭示了锚固节理岩体的破坏特点。

Macro micro mechanical study on bolted joint subjected to shear loading based on DEM

In order to study the failure characteristic and anchorage mechanism of bolted rock mass，a series of shear tests of numerical model with and without bolt have been carried out by taking advantage of modified bilinear constitutive model of bolt based on DEM in varying boundary conditions.Through the comparison of obtained results，the macro mechanical response of the whole bolted rock joint model was discussed.Besides，the evolution process of contact force and particle’s rotation radian in bolted joint model was investigated at microscopic level.Obtained results can be shown from two aspects：① Macroscopic aspect： the increase of the component of axial force acting perpendicularly to joint leads to an increase in joint strength due to friction forces so as to promote the cohesion of joint.With the increase of normal stress，the contribution of bolt to the peak shear stress of joint becomes smaller.It can reveal the anchorage mechanism while using bolt to reinforce jointed rock mass to some extent.② Microscopic aspect： the contact compression force emerged between particles and the locations of particles are evolving all the time and will redistribute during the shearing process under the combined action of compression shear load and boundary displacement constraint.Higher contact force can be generated around the bolt and at the heave part of joint which will result in the generation of tension cracks.While at the intersection of bolt and joint，particles will rotate to a large extent and shear cracks will emerge.Therefore，the failure characteristic of bolted rock joint can be revealed at microscopic level.