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摘要: 为探讨天津滨海新区典型软土的循环变形特性, 采用不排水循环三轴试验, 结合扰动状态概念, 在考虑土体结构屈服压力基础上, 提出了一种能考虑土体在循环荷载作用下结构逐渐破坏的扰动函数, 建立了一种反映土体在循环荷载作用下土体结构破坏的塑性变形经验公式, 并通过动三轴试验结果对所提经验公式进行了检验。分析结果表明: 结构性软土在循环荷载作用下产生的累积塑性应变和振动次数的关系分为稳定型和破坏型2种典型情况; 累积塑性应变随振动次数的增加而增大; 相同的围压作用下, 存在一个临界循环应力比, 其上限值随着围压的增大而减小。可见, 所提经验公式很好反映了土体在交通荷载下的变形特性。Abstract: In order to analyze the deformation characteristics of structured soft clay in Tianjin Binhai New Aera, dynamic triaxial test was conducted under traffic load, soil structure's yield pressure was considered based on the disturbed state concept, a disturbed function was put forward which considered the gradual destruction of soil structure under cyclic load, an empirical formula of plastic deformation was proposed and vertified by using the test. Analysis result shows that the relationship between accumulative plastic strain and cyclic number under cyclic load is divided into stable type and destroyed type. Accumulative plastic strain increases with the increase of cyclic number. There exists a critical cyclic stress ratio under the same confining pressure. The maximum of critical cyclic stress ratio decreases with the increase of confining pressure. Obviously, the empirical formula reflects the deformation characteristics of soil under traffic loadi.
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图 1 原状土和扰动土压缩曲线对比
Figure 1. Comparison of compression curves for natural clay and disturbed clay
图 2 累积塑性应变与振动次数变化曲线对比
Figure 2. Comparison of variation curves for plastic strain and disturbed number
图 4 循环荷载作用下试验与预测结果
Figure 4. Predicted and experiment results of plastic strains under cyclic load
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