砂板岩加卸荷力学特性试验研究及工程应用

发布时间：2018-05-18 22:21

本文选题：节理岩体 + 声波波速　；参考：《三峡大学》2015年硕士论文

【摘要】：论文选取四川雅砻江两河口水电站边坡砂板岩为对象，预制0°、30°、45°、60°、90°等5种贯通节理，对预制节理试样进行了声波波速测试，开展砂板岩完整试样和预制节理试样的单轴压缩试验，三轴压缩试验及三轴卸荷试验，模拟岩体在不同节理倾角、不同围压、不同卸荷速率下的受力状态，研究分析了砂板岩在加卸荷条件下的力学特性，并将研究成果应用到该工程中，论文的主要研究内容及结论如下： 1）节理试样声波波速测试和单轴压缩试验结果表明，随着节理倾角的增大，试样的波速呈增大趋势，节理岩体波速衰减率随节理倾角的变化规律可以用二次函数来表示： V0.0000120.00210.1137。随着节理倾角的增大，峰值强度和弹性模量呈U型变化，最小值出现在60°倾角节理试样处。45°和60°试样石膏面发生了错动，其它节理试样均发生脆性破坏，破坏面穿越了节理面。 2）三轴压缩试验结果表明，对于完整试样，随着围压等级的升高，试样的屈服特征愈加显著；不同节理倾角下，试样的应力-应变曲线形态有较大差异；完整和节理试样的弹性模量和变形模量随着围压等级的升高呈非线性增长的特征；对围压和峰值强度进行拟合，Mohr-Coulumb准则比Hoek-Brown准则拟合精度高。45°、60°节理试样为顺节理面滑动破坏，0°、30°、90°节理试样为穿越节理面的破坏，表明节理试样的破坏特征具有各向异性特征。 3）三轴卸荷试验结果表明，加载阶段试样的力学特性与三轴压缩试验相似，，在卸荷阶段，45°和60°节理倾角试样卸荷之后应力几乎不变，应变快速增长，无破坏阶段，其它节理倾角试样均存在破坏阶段；变形模量随着卸荷量的增加不断减小，在卸荷量小于60%时减小幅度不大，卸荷量在60%-100%时为非线性大幅度减小，60°倾角节理试样的变形模量降幅最大；节理试样的卸荷试验的峰值强度随节理倾角呈U型变化，60°节理试样的强度最小，90°最大；卸荷对试样强度参数的影响主要体现为对粘聚力的减小；与三轴压缩试验相比，卸荷试验中试样产生的裂纹更多，破坏程度在增加。随着围压等级的升高，完整试样和节理倾角为0°、30°、90°的试样的破坏形式由拉剪破坏向压剪破坏过渡，破坏面穿越节理面，45°、60°倾角节理试样为顺节理面滑动破坏，岩块均完好；卸荷速率对节理试样卸荷阶段中的强度、变形、破坏特征均有不同程度的影响。 4）运用节理试样三轴卸荷试验的研究成果，对两河口水电站某边坡进行二维有限元计算，开挖面附近向坡外的位移随着卸荷速率的增大有较大幅度的增长，塑性区也在不断扩展，建议在实际开挖过程中考虑开挖方案对岩体卸荷速率的影响，以保证工程的顺利进行。
[Abstract]:In this paper, the sand slate of the slope of Lianghekou Hydropower Station in Yalong River, Sichuan Province is selected as the object, and 5 kinds of connecting joints are prefabricated, such as 0 掳30 掳(45 掳) and 60 掳(90 掳). The acoustic wave velocities of the prefabricated jointed specimens are measured, and the uniaxial compression tests of the intact slate and prefabricated joints are carried out. Triaxial compression test and triaxial unloading test simulate the stress state of rock mass under different joint inclination angle, different confining pressure and different unloading rate. The mechanical properties of sand slate under loading and unloading conditions are studied and analyzed. The main research contents and conclusions are as follows: 1) the results of acoustic wave velocities and uniaxial compression tests show that the wave velocities of jointed rock mass increase with the increase of joint inclination angle, and the attenuation rate of wave velocity of jointed rock mass can be expressed by quadratic function: V0.0000120.00210.1137. With the increase of the dip angle of joints, the peak strength and modulus of elasticity change in U shape. The minimum value appears at the plaster face of 60 掳inclination joint, and the brittle failure occurs in all other joints, and the failure surface passes through the joint surface. 2) the results of triaxial compression test show that the yield characteristics of the specimen become more obvious with the increase of confining pressure grade, and the shape of stress-strain curve is different with different joint inclination angle. The elastic modulus and deformation modulus of the intact and jointed specimens increase nonlinear with the increase of the confining pressure grade. The fitting of confining pressure and peak strength by Mohr-Coulumb criterion is more accurate than that by Hoek-Brown criterion. The specimen of 60 掳joint is sliding failure of 0 掳/ 30 掳/ 90 掳along the joint plane, which indicates that the fracture characteristic of the joint specimen has anisotropic characteristics. 3) the results of triaxial unloading test show that the mechanical properties of the specimens in the loading stage are similar to those in the triaxial compression test. After unloading, the stress of the specimens with 45 掳and 60 掳joint inclination angle is almost unchanged, the strain increases rapidly and there is no failure stage. The deformation modulus decreases continuously with the increase of unloading amount, and decreases little when the unloading amount is less than 60. When the unloading amount is between 60% and 100%, the maximum reduction of deformation modulus is obtained for the specimen with 60 掳inclination joint, and the maximum strength of 60 掳joint specimen is 90 掳when the unloading strength of the joint specimen varies with the U-shape angle of the joint inclination angle, and the deformation modulus of the joint specimen decreases greatly when the unloading amount is between 60% and 100%, and the maximum value is 90 掳when the unloading strength of the joint specimen is U-shaped. The influence of unloading on the strength parameters of the specimen is mainly reflected in the reduction of the cohesive force, and compared with the triaxial compression test, the specimen produces more cracks and the degree of failure increases. With the increase of confining pressure grade, the failure form of the intact specimen and the specimen with a dip angle of 0 掳or 30 掳~ 90 掳is changed from tension-shear failure to compression-shear failure, and the failure surface is sliding along the joint surface through 45 掳~ 60 掳inclined joint, and the rock block is intact. The unloading rate has different effects on the strength, deformation and failure characteristics of jointed specimens during unloading. 4) based on the research results of triaxial unloading test of jointed specimens, a slope of Lianghekou Hydropower Station is calculated by two-dimensional finite element method. The displacement near the excavation surface outside the slope increases greatly with the increase of unloading rate. The plastic zone is also expanding and it is suggested that the influence of excavation scheme on the unloading rate of rock mass should be considered in the actual excavation process in order to ensure the smooth progress of the project.
【学位授予单位】：三峡大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU45

【参考文献】