循环荷载作用下红砂岩风化土动强度特性试验研究

EXPERIMENTAL STUDY OF DYNAMIC STRENGTH CHARACTERISTICS FOR RED SANDSTONE WEATHERED SOIL UNDER CYCLIC LOADING

利用GDS动三轴试验系统,采用单轴加载的方式对红砂岩风化土进行多组固结不排水三轴试验,研究不同围压及固结应力比对红砂岩风化土动强度变化规律的影响。研究表明:循环荷载作用下红砂岩风化土的变形发展规律在不等向与等向固结条件下有很大差异;在等向固结条件下,围压的增加有助于动强度的提高;而由于红砂岩风化土的崩解破裂性和固结静偏力的剪切作用,使红砂岩风化土在不等向固结条件下的动强度小于等向固结条件下的动强度;不同围压对红砂岩风化土动应力比与振次的影响效果不显著,试样都在1000个循环振次内发生破坏。最后,根据选定的破坏标准给出了相应的动强度曲线和动抗剪强度指标。

In order to study the influence of different confining pressure and consolidation stress ratio on the dynamic strength of red sandstone weathered soil,a series of consolidated undrained triaxial tests were carried out by GDS dynamic triaxial test system under uniaxial loading.The results showed that:the deformation development law of red sandstone weathered soil under cyclic loading was quite different between different consolidation conditions.Under the condition of isotropic consolidation,the increase of confining pressure was helpful to the improvement of dynamic strength.Due to the disintegration and fracturing of red sandstone weathered soil and the shear action of consolidating deviatoric static stress,the dynamic strength of weathered soil under the condition of anisotropic consolidation was less than that under the condition of isotropic consolidation.The effect of different confining pressures on the dynamic stress ratio and vibration frequencies of red sandstone weathered soils were not significant,and the specimens were destroyed within 1000 cycles.Finally,according to the selected failure criteria,the corresponding dynamic strength curve and dynamic shear strength index were obtained.