【摘要】 利用土工静力–动力液压三轴–扭转多功能剪切仪,进行了非均等固结条件下的应力控制式轴向-扭转双向耦合循环剪切试验,探讨了初始大主应力方向角、循环剪切荷载分量比值及循环应力水平对饱和海洋黏土孔压与强度特性的影响。结果表明:初始大主应力方向角对双向耦合剪切下孔压特性影响显著,随着角度的增大,残余孔压发展水平升高,同时波动孔压幅值也在增大,同时建立不同初始大主应力方向角下归一化残余孔压比与归一化循环次数比拟合关系。在固定加载路径所形成的椭圆面积不变条件下,竖向与扭转向荷载分量的比值存在某一临界值,对应此临界值,残余孔压最低。随着循环应力比的增大,波动孔压幅值与残余孔压均在增大,但高应力水平与低应力水平下孔压发展存在较大差异。此外由不同循环应力比下孔压时程曲线确定出临界循环应力比。初始大主应力方向角对动强度影响显著,随角度的增大动强度逐渐降低。动强度曲线显示循环应力比与循环剪切破坏次数的对数基本呈直线关系。更多还原

【Abstract】 The apparatus for static and dynamic universal triaxial and torsional shear soil tests is employed to perform stress-controlled coupling vertical and torsional shear tests under different three-dimensional initial anisotropic consolidation stress conditions.Through experimental tests the effects of the initial orientation angle of the major principal stress,the ratio of the two stress components and the cyclic stress level on the pore water pressure and the strength of the saturated marine clay are examined.The initial orientation angle of the major principal stress has a significant influence on the characteristics of pore water pressure: as the angle increases,both the residual pore water pressure and the amplitude of fluctuated pore water pressure increase.Meanwhile,the relations between the normalized residual pore water pressure ratio and the cyclic number ratio with different initial orientation angles of the major principal stress are established.Under the conditions of keeping the area bounded by the elliptical stress path unchanged,there exists a certain critical value for the ratio of the axial and torsional shear stresses.At this critical value,the residual pore water pressure is the lowest.Both the fluctuated pore water pressure and the residual pore water pressure increase with increasing cyclic stress ratio.However,there is great difference between the high and the low stress levels.Furthermore,the critical cyclic stress ratio is determined according to the time history curves of pore water pressure under different cyclic stress ratios.The initial orientation angle of the major principal stress has a significant influence on the dynamic strength: as the angle increases,the dynamic strength decreases.The dynamic strength curve indicates that there is basically a linear relationship between the cyclic stress ratio and the logarithm of the cyclic number required at failure.更多还原