三轴加载过程中大理岩力学及声波响应特征研究

A Study on the Mechanical Properties and Acoustic Response Characteristics of Marble in the Process of Triaxial Mechanical Loading

孟英峰 杨风强 李诚 尹瀚翔 刘厚彬

MENGYingfeng YANGFengqiang LICheng YINHanxiang LIUHoubin

油气藏地质及开发工程国家重点实验室·西南石油大学, 四川 成都 610500 中国石油西南油气田公司川西北气矿, 四川 江油 621700

State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China Northwest Sichuan Gas District, PetroChina Southwest Oil & Gas Field Company, Jiangyou, Sichuan 621700, China

深部地层岩石所处力学环境异常复杂，高应力下岩石力学性能、破坏规律及声波响应特征研究可为深井关键参数科学化设计提供依据。对大理岩开展了不同围压条件下的三轴力学实验，分析了不同围压条件下加载过程中大理岩的应力-应变、声波特征，探讨了强度准则适用性和岩石应力-应变与动态声学响应机制。研究表明，力学加载过程中，岩样波速变化分为“迅速增加-匀速增加-阶梯下降”和“迅速增加-匀速增加-保持稳定-阶梯下降-减速下降”两种类型，在岩样破坏之前，岩样的波速和振幅均有不同程度的减小；随着围压的增加，大理岩抗压强度和弹性模量均增加，岩样破坏形式由劈裂式向剪切式过渡。围压对大理岩次生裂纹的产生有抑制作用，直线型Morh-Coulomb准则和单参数Bieniawski强度准则分别适用于低围压和高围压条件下大理岩的强度特征描述。研究为深井岩石破裂的预测以及强度准则的建立提供了重要理论依据。

The mechanical environment of deep stratum rocks is extremely complex. The study of rock mechanical properties, failure laws and acoustic response characteristics under high stress can provide a basis for the scientific design of key parameters of deep wells. This paper carried out triaxial mechanical experiments on marble under different confining pressure conditions, analyzed the stress-strain and acoustic characteristics of marble during loading under different confining pressure conditions, and discussed the applicability of strength criteria and rock stress-strain and dynamics, acoustic response mechanism. Research shows that during the mechanical loading process, the wave velocity of the rock sample can be divided into two types: “rapid increase-uniform increase-step down” and “rapid increase-uniform increase-maintain stability-step down”; before the rock sample is damaged, the wave speed of the rock sample and amplitude of the rock sample decrease in different degrees; with the increase of confining pressure, the compressive strength and elastic modulus of marble increase, and the failure mode of the rock sample changes from splitting to shearing. Confining pressure has an inhibitory effect on the occurrence of secondary cracks in marble; the linear Morh-Coulomb criterion and the single parameter Bieniawski criterion are applicable to the description of the strength characteristics of marble under low and high confining pressures, respectively. The research in this paper provides an important theoretical basis for the prediction of rock fracture in deep wells and the establishment of strength criteria.

10.11885/j.issn.16745086.2021.04.29.04