不同应力路径下砂岩分段变速连续卸荷变形特性研究

为研究高陡边坡岩体开挖卸荷过程中的变形问题，结合实际高陡边坡岩体开挖应力变化特征，分别开展了室内三轴加载试验及卸围压卸轴压、卸围压恒轴压、卸围压增轴压3种应力路径下的分段变速卸荷试验。结果表明，在每种应力路径下，岩样分段变速卸荷的变形模量都随初始围压的升高而增大，变形模量随卸荷当量的增加而减小。卸荷当量为0～60%时，变形模量基本都随卸荷当量线性下降，降幅一般都在0～5%之间；卸荷当量为60%～100%时，变形模量降幅突然变大，岩样临近破坏。不同应力路径对于砂岩的变形特性影响各不相同，卸围压恒轴压的影响最为显著，卸围压卸轴压次之，而卸围压增轴压的影响最小。

Study on Deformation Characteristics of Sandstone in Different Stress Paths and Different Speed Continuous Unloading

In order to study the deformation of high and steep slope rock mass during excavation and unloading process,combined with the actual high and steep slope rock mass excavation stress change characteristics,the laboratory triaxial loading tests of rock mass and the different speed unloading tests under three stress paths of confining pressure unloading and axial pressure unloading,confining pressure unloading and constant axial pressure,and confining pressure unloading and axial pressure boosting are carried out.The research results show that,under each stress path,the deformation modulus of rock specimen under variable-speed unloading increases with the increase of initial confining pressure grade,and decreases with the increase of the unloading equivalent.When the unloading equivalent is between 0 and 60%,the deformation modulus decreases linearly with unloading equivalent,and the decrease is generally between 0 and 5%.When the unloading equivalent is between 60% and 100%,the decrease of deformation modulus suddenly becomes larger,and the rock specimen is approaching destruction.Different stress path has different effects on the deformation characteristics of sandstone,in which,the effect of the path of confining pressure unloading and constant axial pressure is the most significant,followed by the path of confining pressure unloading and axial pressure unloading,and the path of confining pressure unloading and axial pressure boosting has the least influence.