中文摘要：

柱状节理岩体几何特征的复杂性为评价柱状节理硐室的稳定性和破坏模式带来了极大的困难，以柱内陡倾角隐节理面为例，该类型节理的存在导致节理密度增大，围岩力学性质被削弱，但同时该节理面的镶嵌特征又十分明显，增强了围岩力学性质。为进一步认识和评价柱状节理岩体几何参数对硐室稳定性的影响，在深入分析其几何分布特征的基础上，采用DDA深入研究这些几何特征对柱状节理硐室稳定性的影响，并以此为基础，对柱状节理岩体的破坏模式进行探讨。研究结果表明：（1）保持柱内近水平隐节理面的倾角不变，当柱间节理面与水平隐节理面夹角小于20°时，硐室稳定性很好；夹角为90°时，硐室稳定性最差；当柱问节理面与柱内近水平隐节理面节理倾角组合为0°和90°时，顶拱的稳定性最差。（2）节理间距对柱状节理硐室稳定性的影响主要体现在节理间距绝对值和节理间距比两方面，对于节理间距比，随着比值增大，硐室越稳定，反之亦然；对于节理间距绝对值，随着其增大，硐室越稳定，并且增加到一定程度会形成不可动块体，硐室稳定性大大增加。（3）柱状节理硐室破坏模式为：首先是部分被柱内陡倾角隐节理所切割裸露在外的小柱体首先发生张拉破坏，而后沿柱间节理面发生剪切破坏，最后沿柱内近水平隐节理面开始向临空面垮落；同时顶拱节理面在切向应力作用下也会发生一定的破坏。

英文摘要：

Abstract： The complexity geometric features of columnar joint bring great difficulties for the evaluation of tunnel stability and failure pattern. Taking the plumose joint inside column as an example, on one hand, the mechanical properties is weakened for the existence of this type of joint, which leading to the increase of joint density, and on the other hand, the inlay characteristic of this type of joint is also very obviously, which could enhance its mechanical properties. Based on the in-situ investigation of the geometric distribution of columnar joints, the impact of these geometric features on the stability of columnar joints is studied using DDA and the failure pattern of columnar joints is discussed. The research results shows that： （1） When the angle of joint between the column and horizontal joint inside column is 90~ , the tunnel stability is the worst, and when the angle is less than 20~ , the tunnel stability is well. （2） The effects of joint space on the stability of underground tunnel mainly include twoaspects, the ratio of joint spacing and the absolute value of the joint spacing. For the joint spacing ratio, with the ratio increased, the tunnel is more stable, and vice versa. For the absolute value of joint spacing, with increasing of it, the stress acting on the block is decreased, and the tunnel is more stable. （3） The joints inside the columnar joints are so well developed that the columnar will first break inside the column, and then it will break between columns. At last, the small columnar would collapse under the effect of gravity and excavation disturbance. In addition, for the crosswise joints are so well developed, large scale of collapse would happen in severe cases. The columnar joints at arch would also break under the tangential stress.