开挖扰动诱发主应力轴偏转下软岩力学试验研究

Mechanical experimental study of soft rock under deflection of principal stress induced by excavation disturbance

为研究地下工程开挖过程中应力方向旋转对弱胶结软岩强度的影响,以煤矿巷道工程软岩为对象,采用GDS空心圆柱测试系统开展平均主应力固定、偏应力改变条件下主应力轴旋转应力路径的软岩力学特性试验,研究偏应力及主应力轴旋转角对弱胶结软岩试件应力-应变特性及强度特性影响.基于试验结果并结合幂次函数模型,建立主应力轴旋转条件下弱胶结软岩剪应变数学公式.研究结果表明:弱胶结软岩的变形随着应力主轴的旋转而累加,主应力轴旋转角增大,轴向应变和剪应变速率迅速增加,累积形变量也不断增大,主应力轴旋转会加速试件轴向应变的累积.所建剪应变公式能较好地预测弱胶结软岩在应力主轴旋转下的剪应变变化规律,可应用于实际工程的变形预测.

In order to study the influence of the stress direction during underground engineering excavation on the strength of weakly cemented soft rock,the soft rock samples were obtained from the coal mine roadway engineering soft rock and the GDS(Global Digital Systems)hollow cylindrical test system was used to determine the average fixed principal stress.The deviation stress under the action of the rotation of the principal stress axes,the stress path of the soft rock mechanics,and rotation angle of the principal stress axes of weakly consolidated soft rock specimen were studied,and the stress-strain characteristics as well as the influence of the strength characteristics was determined.Based on the test results and power function model,an empirical equation of the shear strain of weakly consolidated soft rock under the principal stress axis was established.The results show that the deformation of weakly consolidated soft rock accumulates with the rotation of the principal stress axis,and with the rotation angle of the principal stress axis increases,the axial strain and shear strain rates increase rapidly,and the cumulative deformation also increases.The rotation of the principal stress axis accelerates the accumulation of the axial strain of the specimens.The shear formular can effectively predict the shear strain variation law of weakly consolidated soft rock under the stress axis rotation.Additionally,it can be applied in the deformation prediction of practical engineering.