卸荷速率对粉砂岩力学特性的影响

Effect of unloading rate on the mechanical properties of siltstone

围绕“向地球深部进军”的国家战略,超前布局、抢占深地研究高地、积极推动深地开发基础科学问题的探索已迫在眉睫.结合地下工程施工特点,本文设计了恒轴压卸围压实验,以粉砂岩为研究对象,利用围压增量比概念探讨了不同卸荷速率对其力学特性的影响规律,实验发现:卸荷过程以横向变形为主,扩容现象明显,卸荷时间、应变、弹性模量、泊松比及能量对围压降敏感程度随卸荷速率增加呈幂函数降低,且敏感期转向破坏点,表明高卸荷速率滞后且钝化了岩石各参数对围压降的响应,但使岩爆几率增加,这为地下工程尤其是深地工程提供了参考和依据.

Focusing the national strategy of"marching to the deep of the earth",it is urgent to advance the layout,seize the highlands for deep research,and actively promote the exploration of basic science in the deep development.Combined with the construction characteristics of underground engineering,this paper designs a constant axial pressure unloading confining pressure experiment.Taking siltstone as the research object,the influence of different unloading rates on its mechanical properties is discussed by using the concept of confining pressure increment ratio.The experiment finds that the unloading process is dominated by lateral deformation,and the expansion phenomenon is obvious;the sensitivity of unloading time,strain,elastic modulus,Poisson′s ratio and energy to confining pressure drop decreases as a power function with the increase of unloading rate,and the sensitive period turns to the failure point;indicating the high unloading rate lags behind and inactivates the response of rock parameters to confining pressure drop,but increases the probability of rock burst.It provides a reference and basis for underground engineering,especially deep engineering.