基于动力显式方法的岩体结构面剪切破坏特征研究

岩体中大量存在的各种不连续面，如断层、节理、裂隙等，是影响岩体工程力学特性的最重要的因素，因此，对岩体中广泛存在的结构面工程特性的研究具有重要的工程意义。在动力显式方法的基础上，对规则锯齿状的结构面进行剪切破坏特征进行分析，并进行室内模型试验。对数值模拟与模型试验的结果进行对比分析，得出归一化的锯齿状结构面在不同法向应力作用下的剪切破坏力学行为及重要剪切破坏规律，并验证了利用动力显式方法进行节理岩体工程力学特性研究的适应性。研究表明：在一定法向应力水平下，规则锯齿状结构面剪切破坏是随着剪切位移的增长而不断扩展，主要表现为结构面上的等效塑性应变分布范围与深度的不断扩大，最后达到纯摩擦的残余强度状态；等效塑性应变的扩展规律一般是在剪切方向上从试样两侧逐渐向中间扩展，对于下侧结构面而言，在达到剪切应力峰值之前，剪切应力主要分布在试样中相背剪切速度方向的一侧，在剪切峰值之后，随着结构面破坏范围不断增大，剪切应力分布趋于均匀；当正应力不断增大时，结构面发生爬坡滑移越来越困难，结构面破坏深度不断增大，峰值剪应力所对应的破坏模式逐渐变为直接剪断锯齿破坏。

STUDY OF SHEAR FAILURE CHARACTERISTICS OF ROCK STRUCTURAL SURFACE BASED ON DYNAMIC EXPLICIT METHOD

The most important influencing factor of rock mass strength characteristics is the discontinuities randomly distributed in rock mass. Thus，study of the mechanical properties of rock discontinuities is of great engineering significance. Based on the dynamic explicit method，the shearing failure characteristics of regular sawtooth-like structural surface is numerically simulated；and relevant model test is carried out. Comparing the numerical result with test result，the shearing failure behavior and failure patterns of normalized sawtooth-like structural surface under different normal stresses are obtained. Consequently，the applicability and reliability of the employed numerical simulation method are verified. The results indicate that：(1) Under certain normal stress，shearing failure of regular sawtooth-like structural surface develops continuously with the increase of shearing displacement，suggesting that the distribution and depth of equivalent plastic strain extended. Finally，the shearing failure reaches pure friction residual strength state. (2) The growth of rock equivalent plastic strain usually propagates from two ends to the middle gradually. For the low structural plane，shear stress is mainly distributed in the side opposite to shear velocity before reaching the peak value. After the peak value，the distribution of shear stress is uniform with increase of failure extent of structural plane. (3) When the normal stress increases，the displacement of structural plane climbing becomes more difficult and thus the failure depth increases. Thus，the failure pattern corresponding to the peak stress is becoming direct shearing sawtooth failure.