自然与饱水状态下深部斜长角闪岩蠕变特性

张春阳¹，曹平¹，汪亦显^{1, 2, 3}，宁果果¹

(1. 中南大学 资源与安全工程学院，湖南 长沙，410083；2. 合肥工业大学 土木与水利工程学院，安徽 合肥 230009；3. 长江水利委员会长江科学院，湖北 武汉 430010)

摘 要：通过金川深部斜长角闪岩单轴压缩蠕变实验，选取典型蠕变曲线，发现该岩石黏弹性、黏塑性变形较瞬时变形偏小，卸载后弹性后效不显著。在5.1 MPa轴向应力下，自然状态的岩样近似纯弹性特征。饱水状态下岩样瞬时强度σ′_b和长期强度σ′_∞总体低于自然状态，且σ′_∞已接近深部高地应力，因此，对于深部节理、裂隙很发育的岩体，应特别注意巷道排水，防止围岩因长期强度降低而导致巷道变形和破坏。自然与饱水状态下岩样瞬时弹性应变ε_me、瞬时塑性应变ε_mp随应力增大而增加，但增速逐渐放缓，饱水状态下塑性变形更显著；相同应力下，饱水状态岩样蠕变量大于自然状态，应变速率也总体快于自然状态，2种状态的蠕变速率在20~30 h时都逐渐稳定，且速率曲线随应力增大，微裂隙压密，彼此逐渐靠近，岩样处于相对硬化阶段；当轴向应力达到66.3 MPa后，饱水状态蠕变速率有相对加速趋势，速率曲线随应力增大先往左下移动，再朝右上移动，而自然状态蠕变速率曲线总体向右上移动。最后，通过蠕变数据分析，推导γ=ασ^k型经验方程，对蠕变试验数据进行回归拟合，拟合结果证明该蠕变经验模型的正确性。金川矿区斜长角闪岩蠕变实验研究为分析深部巷道该类围岩流变稳定性及支护方案优化等提供有效帮助。

关键词：斜长角闪岩；单轴压缩蠕变实验；长期强度；应变速率；蠕变经验模型；回归拟合

Creep characteristics of plagioclase hornblende rock under natural and water-saturated conditions in deep underground

ZHANG Chunyang¹, CAO Ping¹, WANG Yixian^{1, 2, 3}, NING Guoguo¹

(1. School of Resources and Safety Engineering, Central South University, Changsha 410083, China;2. School of Civil Engineering, Heifei University of Technology, Hefei 230009, China;3. Research Center on Water Engineering Safety and Disaster Prevention of MWR, Wuhan 430010, China)

Abstract:According to plagioclase-hornblende rock in Jinchuan deep underground mine uniaxial compression creep test results, after selection typical creep curves, it is found that viscoelastic and viscoplastic deformation are significantly less than instantaneous deformation, elastic after-effect is not obvious after unloading. Under 5.1 MPa of uniaxial stress, rock samples show pure elastic properties in natural condition. Under water condition, both instantaneous uniaxial compressive strength σ′_b and long-term strength σ′_∞ are generally lower than nature condition, σ′_∞ approaches deep high underground stress, therefore, under high stress conditions in deep underground, especially joints, fractured rock mass, should pay particular attention to drainage, so as to prevent rock deformation and damage due to long-term strength σ_∞ reduction in roadway. Instantaneous elastic and plastic strain ε_me, ε_mp increases with stress, but the speed decreases, plastic deformation characteristics becomes more conspicuous in water-saturated condition. Under the same stress, water-saturated condition’s creep is higher than that of natural condition, and strain rates are generally faster, two conditions’s creep rates all turn stable in 20-30 h, rate curves approach each other with stress increases and micro-cracks compact, rock samples turn into a relative hardening stage. While stress reaches 66.3 MPa, water-saturated condition’s strain rates accelerate relatively, curves first move down-left, then back to upper-right, but in natural condition, strain rate curves generally move to upper-right. Finally, in the light of creep data characteristics, empirical equation γ=ασ^k is introduced to fit the experimental data. The results prove that the empirical creep model is correct. The creep experimental research of plagioclase hornblende rock in Jinchuan underground mine can provide effective help for analyzing deep roadway rheological stability and support optimization.

Key words:plagioclase-hornblende rock; uniaxial compression creep test; long-term strength；strain rates; empirical creep model; regression and fitting