软硬互层状类岩石试样力学特性的三轴试验研究

Triaxial Test Study on the Mechanical Properties of Soft-Hard Interbedded Rocklike Specimens

句容抽水蓄能电站工程区内发育有薄层泥岩与白云岩互层状的地层结构,对软硬互层状地层开展力学性质的研究对电站的建设和安全评价有重要意义。采用相似材料制作软硬互层状类岩石试样,对各组试样进行常规三轴试验,研究不同夹层倾角、夹层厚度比及围压条件下试样的强度规律及破坏形式。结果表明:厚度比为1∶1∶1和1∶3∶1时,随角度的增大,试样强度降低。不同厚度比倾角相同的试样强度接近,破坏形式相同。增大软岩层的厚度会显著降低试样整体的强度。倾角为0°时,试样破坏后软岩破碎,无法确定主破坏面。随着角度的增大,试样破坏形式发生变化,沿软岩和两侧交界面发生错动。倾角为45°时,破坏面贯穿试样,软岩相对完整。厚度比为3∶1∶3的不同夹层倾角试样,主要发育1~2个贯穿试样的主破坏面以及少量连接主破坏面与软硬岩层交界面的次级破坏面。夹层倾角在0°~45°范围时,随着倾角的增大,试样的强度参数逐渐降低。

In the engineering area of Jurong pumped storage power station,there is a layered structure of mudstone and dolomite.It is of great significance to study the mechanical properties of soft and hard interbedded strata for the construction and safety evaluation of power stations.The soft-hard interbedded rock samples are made of similar materials.The conventional triaxial tests are carried out on each group of samples to study the strength rule and failure mode of the samples under different dip angles,thickness ratios and confining pressure.The results show that when the thickness ratio is 1∶1∶1 and 1∶3∶1,the strength of the sample decreases with the increase of the angle.The specimens with the same dip angle and different thickness ratios have similar strength and the same failure mode.Increasing the thickness of the soft rock layer will significantly reduce the overall strength of the sample.When the dip angle is 0 degree,the soft rock is broken after the sample is destroyed,and the main failure surface can not be determined.With the increase of the angle,the failure mode of the specimen changes,and the dislocation occurs along the interface between the soft rock and the two sides.When the dip angle is 45°,the failure surface penetrates the specimen,and the soft rock is relatively complete.There are mainly 1-2 main failure surfaces through the specimen and a small number of secondary failure surfaces connecting the interface between the main failure surface and the soft and hard rock stratum in the specimens with different interlayer dip angles whose thickness ratio is 3∶1∶3.When the dip angle of the interlayer is in the range of 0°-45°,with the increase of dip angle,the strength parameters of the specimen decrease gradually.