波浪荷载纯圆应力路径下海床粘土动力特性研究

    Study on dynamic characteristics of sea-bed clay under pure circular stress path under wave load

    • 摘要: 目前,波浪荷载对与饱和淤泥质粉质粘土的影响的研究仍然以室内动三轴实验为主,无法真实地反映波浪荷载影响造成的主应力轴连续旋转这一特点。本文利用DHCA动态空心圆柱扭剪仪,对浙江台州淤泥质粉质粘土,进行了考虑主应力轴旋转的波浪荷载应力路径下不同循环应力比和循环圈数的循环剪切试验以及循环后静力剪切试验。研究分析了波浪荷载作用下淤泥质粉质粘土孔隙水压力发展、应力应变发展规律、骨干曲线发展以及刚度衰减等动力特性,并建立了应力应变骨干曲线与循环圈数的关系。此外,相同CSR条件下,循环后抗剪强度与循环圈数呈正相关。循环圈数越多的试样,参考模量E50越大,出现了刚度强化的现象,与熟知的土体循环后刚度弱化现象相反。本研究为波浪荷载作用下饱和淤泥质粉质粘土的工程特性评估提供了新的试验依据和理论参考。

       

      Abstract: At present, the study of the effect of wave load on saturated silty clay is still mainly based on the laboratory dynamic triaxial experiment, which cannot truly reflect the continuous rotation of the principal stress axis caused by wave load. In this study, the dynamic hollow cylindrical apparatus (DHCA) is used to carry out cyclic shear tests and post-cyclic tests on Taizhou silty clay with different cyclic stress ratio and cycle numbers under wave loading. The cyclic characteristics, such as the development of pore water pressure, stress-strain relationship, backbone curve and stiffness were studied and analyzed, and the relationship function between the backbone curve and cycle numbers is established. Besides, under the same CSR condition, the shear strength after the wave loading is positively correlated with the cycle numbers. And the shear modulus E50 increases with the increasing cycles, indicating the possible stiffness hardening, instead of the stiffness softening after cyclic loading in most previous triaxial tests. This study provides new experimental evidence and theoretical references for evaluating the engineering properties of saturated silty clay under wave loading.

       

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