不同节理开度及连通率下非贯通节理岩体剪切力学特性研究

Study on the shear mechanical properties of non-penetrating joints with different apertures and connectivity rates

  • 摘要: 结合室内直剪试验和数值模拟手段,研究不同节理开度、节理连通率和法向应力下的非贯通节理岩体宏细观剪切力学行为,系统分析剪切应力-剪切位移曲线和峰值剪切强度、法向位移-剪切位移曲线、应力演化等特征。结果表明:①非贯通节理岩体剪切应力-剪切位移曲线均存在明显峰值,且基本会经历压密阶段、裂纹扩展阶段、峰后破坏阶段和残余摩擦阶段,各工况下剪切曲线形态可划分为峰前上升峰后爬升型(Ⅰ型)、峰前上升峰后阶梯型(Ⅱ型)和峰前台阶峰后爬升型(Ⅲ型);②峰值剪切强度与节理开度、节理连通率呈负相关关系,与法向应力呈正相关关系,峰值法向位移与节理开度、最终法向位移与节理连通率均呈负相关关系,峰值法向位移、最终法向位移均随法向应力的增加而减少;③岩桥未贯通破坏前,节理端部及裂纹延伸处会产生应力集中现象,随着节理连通率、节理开度的增加,应力集中程度增加,岩桥贯通破坏形成剪切断面后,应力集中于断面处。

     

    Abstract: Investigating the shear mechanical properties of non-penetrating jointed rock masses under various joint characteristics is of significant practical importance for underground engineering construction. This paper combines laboratory direct shear tests and numerical simulation methods to study the macroscopic and microscopic shear mechanical behavior of non-penetrating jointed rock masses under different joint apertures, joint connectivity rates, and normal stresses. A systematic analysis is conducted on the shear stress-shear displacement curves, peak shear strength, normal displacement-shear displacement curves, and stress evolution characteristics. The research findings indicate that: ① The shear stress-shear displacement curves of non-penetrating joints exhibit distinct peaks and generally undergo stages of compaction, crack propagation, post-peak failure, and residual friction. Based on the shapes of shear curves under various conditions, they can be classified into pre-peak ascending and post-peak climbing type (Type Ⅰ), pre-peak ascending and post-peak stepping type (Type Ⅱ), and pre-peak stepping and post-peak climbing type (Type Ⅲ); ② The peak shear strength is negatively correlated with joint aperture and joint connectivity rate, and positively correlated with normal stress. The peak normal displacement is negatively related to joint aperture, and the final normal displacement is negatively related to joint connectivity rate. Both the peak and final normal displacements decrease with the increase of normal stress; ③ Before the intact rock bridge fails to penetrate, stress concentration occurs at the joint ends and crack extension areas. As the joint connectivity rate and joint aperture increase, the degree of stress concentration intensifies. After the rock bridge fails to penetrate and forms a shear plane, stress concentration occurs at the plane, and the stress distribution is mainly influenced by the plane morphology.

     

/

返回文章
返回