混凝土-海洋黏土界面剪切试验与数值模拟

Shear test and numerical simulation of concrete marine clay interface

为研究海洋桩基与附近土体的界面力学特性,进行了不同法向应力、土体含水率与压缩度下的混凝土-海洋黏土界面剪切试验,并通过PFC^(2D)离散元方法分析了海洋桩基附近土体剪切带随时间的变化情况。结果表明:压缩量-法向应力曲线符合“双曲线”关系。土体的压缩度随含水率、法向应力的增大而增大,在达到相同的压缩度下,含水率越高或受法向应力越大的土体所用的压缩时间越短。峰值剪切应力随法向应力、压缩度的增大而增大,随含水率的增大而减小。降低土体压缩度或调整土体含水率至塑限附近可提高界面抗剪强度。含水率、法向应力越大,土体的剪缩特性越明显;压缩度越大,土体的剪胀特性越明显。土体剪切带面积随剪切时间先急剧增加,后逐渐减小至稳定值1.13 cm 2左右。压缩度越大,土体剪切带面积越大,但达到峰值剪切带面积所用时间基本相同。含水率越低,土体剪切带面积越大,峰值剪切带面积与剪切时间成正比例。

In order to study the mechanical properties of the interface between pile foundation and marine soil,the shear tests of interface between concrete and marine clay under different normal stress,soil water content and compressibility were carried out,and the variation law of soil shear band near the interface with time was analyzed by PFC^(2D) discrete element method.The results show that the relationship between compression and normal stress can be expressed by hyperbolic model.The compressibility of soil increases with water content and normal stress.Under the same compressibility,the soil with higher water content or higher normal stress has shorter compression time.The peak shear stress decreases with water content and normal stress,and increases with the compressibility in respectively.Reducing the compressibility of soil or adjusting the water content to near the plastic limit can improve the interface shear strength.The shear shrinkage of soil is more obvious with the increase of water content and normal stress.The greater the compressibility,the more obvious the dilatancy of soil.The area of soil shear zone first increases sharply and then decreases with time,and finally stabilizes at about 1.13 cm 2.The shear zone of soil is positively correlated with the degree of compression,but the time consumed from the beginning of the test to reaching the area of peak shear zone is basically the same.The lower the water content,the larger the area of soil shear zone,and the area of peak shear zone is positively proportional to the shear time.