水电工程的库岸边坡岩体在运营中难免遭遇卸荷作用,水位周期性升降也使岸坡部分岩体结构进一步劣化,易引发滑坡,严重威胁居民的生命和财产安全,故开展水压循环作用下节理砂岩的卸荷力学特性研究十分必要。本文以三峡库区典型岸坡的砂岩为试验对象,设计开展不同倾角交叉节理砂岩在循环水压作用下的卸荷力学特性试验,重点分析了循环水压作用对砂岩卸荷力学特性和微观结构的影响。研究表明:交叉节理岩样的强度主要受主节理倾角α的影响,α从0°增加到90°,峰值强度依次增大;同一α下,次节理倾角β从0°到90°,峰值强度呈现先减小后增大的趋势,总体变化幅度较小;弹性模量和变形模量随着α的增大依次增大,随β的增大呈现先减小后增大的趋势;随着水压循环次数的增加,轴向和环向应变不断增大,增加的速度呈现出先增大后减小的趋势;轴向应变和环向应变增量在α=60°时最大,在α=90°时最小;α=60°的节理岩样弹性和变形模量劣化度最大,水压循环作用对60°节理倾角试样的劣化作用最明显。
The bank slope of hydropower project inevitably encounter unloading effect in operation, and the periodic rise and fall of water level will further degrade the structure of some rock mass on the bank slope, which is easy to breed landslide and seriously threaten people's life and property safety. Therefore, it is necessary to study the unloading mechanical characteristics of jointed sandstone under the water pressure circulation. In this paper, the sandstone of typical bank slope in the Three Gorges Reservoir area is taken as the test object, and the unloading mechanical properties of sandstone with cross joints of different angles are designed and tested under the circulating water pressure. The result shows that the strength of the cross-jointed rock samples is mainly affected by the inclination angle of the main joint α. As α increases from 0° to 90°, the peak strength increases successively. Under the same main joint inclination angle, the peak strength decreases first and then increases when the secondary joint inclination angle β comes from 0° to 90°, and the overall change amplitude is small. The elastic modulus and deformation modulus increase with the increase of α, and decrease first and then increase with the increase of β. The axial and circumferential strain increases with the number of water pressure cycles, and the increasing velocity first increases and then decreases. The increment of axial strain and circumferential strain is maximum at α=60° and minimum at 90°. The deterioration degree of elasticity and deformation modulus of the samples at α=60° is the largest, and the deterioration of the samples at α=60° is the most obvious due to water pressure circulation.
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