准确认识岩体结构面的动态接触特征是评价和预测结构面剪切行为的基础。首先，通过FISH语言修正了FLAC^3D软件自带的INTERFACE本构模型，使其能够准确表达粗糙结构面在剪切过程中的力学行为；然后，采用数值模拟和室内试验相结合的方法对剪切过程中结构面接触和受力的分布及其演化规律进行了研究，分析了法向应力和结构面粗糙度系数（JRC）对接触特征的影响规律；最后，研究了结构面表面形貌-接触特征-剪切应力3者间的关系，揭示了结构面剪切应力演化机理。结果表明：FLAC^3D自带INTERFACE模型无法很好地模拟结构面峰后剪切行为，是由于结构面凸起未啃断导致黏聚力和法向应力偏大，通过对INTERFACE破坏单元的黏聚力和法向刚度进行修正可很好地模拟结构面的损伤破坏行为。随着剪切位移增大，结构面的接触面积逐渐减小，但最大渗透深度却不断增加；随着法向应力的增大，结构面的接触面积和渗透深度都增大；随着JRC的增大，结构面的接触面积减小，最大渗透深度增大。剪切过程中结构面接触面积逐渐减小，结构面剪切应力集中现象越来越显著，当INTERFACE单元达到最大剪切应力后，最大剪应力分布范围增大；随着法向应力增大，结构面剪切应力分布范围和高剪切应力的分布范围都增大；随着JRC增大，结构面接触面积减小，但高剪切应力的分布范围显著增大。临界视倾角是判断结构面接触面积的重要参数，其随着结构面剪切位移的增大而增大，但增加速度逐渐变缓，呈幂函数关系；临界视倾角随着法向应力的增大而减小，随着JRC的增大而增大。结构面的剪切应力与接触面积有较强的相关性，不同剪切位移阶段的结构面接触面积比下降速率不同，弹性阶段下降最快，位移-软化阶段次之，残余阶段下降最慢。

Accurate knowledge of the 3D surface dynamic contact characteristics is the basis for the evaluation and prediction of shear behaviors of rock discontinuity. Firstly,the INTERFACE model of the FLAC3D software was modified using the FISH language to accurately represent the mechanical behaviors of rough rock discontinuities during shear. Then,using numerical simulation and indoor experimental methods,the distribution of contact area and shear stress on the surfaces of discontinuities in shear and its evolution characteristics were studied,and the effect of normal stress and joint roughness coefficient roughness (JRC) on the contact characteristics was analyzed. Finally,the relationship between surface morphology,contact characteristics and shear stress was investigated to reveal the mechanism of shear stress evolution of rock discontinuity. The results show that due to the over high cohesion and normal stress caused by the surface bulges that cannot be chewed off,the FLAC3D self contained INTERFACE model cannot simulate the post peak shear behaviors of the rock discontinuity well. The failure behaviors of the rock discontinuity can be well simulated by correcting the cohesion and normal stiffness of the damaged INTERFACE elements. With the increase of shear displacement,the contact area of rock discontinuity decreases gradually,while the maximum penetration depth increases. With the increase of normal stress,the contact area and penetration depth increase. With the increase of JRC,the contact area decreases and the maximum penetration depth increases. With the gradual decrease of the contact area of the rock discontinuity in the shear process,the shear stress concentration phenomenon becomes more obvious. When the INTERFACE elements reach its maximum shear stress,the distribution range of maximum shear stress increases. With the increase of the normal stress,the distribution range of shear stress increases,and the distribution range of the high shear stress also increases. With the increase of JRC,the contact area decreases,while the distribution range of high shear stress increases significantly. The critical apparent dip angle is an important parameter to assess the contact area of the rock discontinuity. The critical apparent dip angle increases with the increase of shear displacement,and its increase rate gradually becomes slower and shows a power function relationship. The critical apparent dip angle decreases with the increase of normal stress,and increases with the increase of JRC. There is a strong correlation between the change of shear stress and the contact area of the rock discontinuity. The decrease rate of the contact area ratio is different in different shear displacement stages. The decrease rate is the fastest in the elastic stage,followed by the displacement softening stage,and the decrease rate is the slowest in the residual strength stage.

1 结构面本构模型的修正

   1.1 自带INTERFACE模型的不足

   1.2 模型修正

2 模型验证

   2.1 室内试验方法

   2.2 数值模拟方法

   2.3 对比验证

3 数值模拟结果与分析

   3.1 接触面积特征及其演化规律

   3.2 剪切应力特征及其演化规律

   3.3 结构面接触与表面形貌的关系

   3.4 结构面剪切应力与接触的关系

4 结论