钙质砂循环剪切特性及抗剪强度弱化机制  

Cyclic shear characteristics and shear strength weakening mechanism of calcareous sand

作　　者：吕亚茹[1] 丁思超 李欣[1] 苏宇宸 王媛 左殿军[3] LYU Yaru;DING Sichao;LI Xin;SU Yuchen;WANG Yuan;ZUO Dianjun(College of Mechanics and Engineering Science,Hohai University,Nanjing,Jiangsu 211100,China;College of Water Conservancy and Hydropower Engineering,Hohai University,Nanjing,Jiangsu 210098,China;Tianjin Research Institute for Water Transport Engineering,Ministry of Transport of the People's Republic of China,Tianjin 300456,China)

机构地区：[1]河海大学力学与工程科学学院,江苏南京211100 [2]河海大学水利水电学院,江苏南京210098 [3]交通运输部天津水运工程科学研究院,天津300456

出　　处：《岩石力学与工程学报》2024年第11期2811-2822,共12页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(52279097,51779264);江苏高校“青蓝工程”。

摘　　要：钙质砂是岛礁建设的重要材料之一,目前关于其循环剪切后的抗剪强度变化还鲜有报道。通过三轴固结排水和不排水剪切试验得到钙质砂和石英砂的抗剪强度,以静荷载下的抗剪强度为依据,开展不同静应力比和动应力比下的三轴不排水循环剪切试验及循环加载后的不排水剪切试验。结果表明:静应力比主要影响孔压发展上限,而动应力比不仅影响孔压发展上限,还影响循环结束时的应变值,这一规律在钙质砂中更为明显。孔压发展与静应力比负相关而与动应力比正相关。在同一循环荷载下,钙质砂累积孔压大于石英砂,并且在高动应力比下更容易发生液化。不同静应力比和动应力比的循环剪切后,砂土的偏应力峰值均有所降低。值得注意的是,以循环剪切结束时刻相比,静应力比的提升在一定程度上有利于循环后钙质砂剪切强度的提升,而动应力比的提升则一定程度上有利于循环后石英砂剪切强度的提升。Calcareous sand is one of the important materials for island construction.There are few reports about the change of shear strength of calcareous sand after cyclic shear.In this paper,the shear strength of calcareous sand and quartz sand was obtained through consolidated drained and undrained triaxial shear tests.Based on the shear strength under static load,undrained cyclic traxial tests under different static stress ratios and cyclic stress ratios,as well as undrained triaxial shear tests after cyclic loading,were conducted.The results show that the static stress ratio mainly affects the upper limit of pore pressure development,while the cyclic stress ratio not only affects the upper limit of pore pressure development,but also affects the strain value at the end of the cycle,which is more obvious in calcareous sand.The development of pore pressure is negatively correlated with the static stress ratio and positively correlated with the cyclic stress ratio.The cumulative pore pressure of calcareous sand is greater than that of quartz sand under the same cyclic loading,making it more prone to liquefaction under high cyclic stress ratios.After undrained cyclic traxial tests with different static stress ratios and cyclic stress ratios,the peak deviatoric stress of sand decreases.It is worth noting that compared with the end of undrained cyclic traxial tests,the increase of static stress ratio is beneficial to the improvement of shear strength of calcareous sand after cyclic loading to a certain extent,while the increase of cyclic stress ratio is beneficial to the improvement of shear strength of quartz sand after cyclic loading to a certain extent.

关 键 词：土力学 钙质砂 循环荷载 静应力比 动应力比 抗剪强度 

分 类 号：TU43[建筑科学—岩土工程]