确定循环荷载作用下吸力锚承载力的塑性上限法

塑性上限分析法是计算静荷载作用下吸力锚极限承载力的一种方法,依据塑性上限分析原理,为了计算静荷载与循环荷载共同作用下吸力锚的承载力,建议了一种基于塑性上限分析理论计算静荷载和循环荷载共同作用下软黏土中张紧式吸力锚循环承载力的方法.该方法首先假定在静荷载作用下吸力锚的破坏模式,并依据静力平衡原理计算静荷载在土体中产生的平均剪应力,然后依据循环强度与土体平均剪应力和循环破坏次数的相互关系确定相应的循环强度,将循环荷载对土体的作用转化成土体强度的变化,再假定吸力锚在循环荷载下的破坏模式与静荷载作用下其破坏模式一致,并依照塑性上限分析原理和土体的循环强度计算强度变化后的承载力.为了验证该方法的合理性,进行了1g条件下的吸力锚模型试验,并应用该方法对模型试验结果进行了预测,预测结果与试验结果吻合较好.

Upper Bound Plasticity Method Determining Bearing Capacity of Suction Anchors with Cyclic Loading

Upper bound plasticity analysis is a method to calculate ultimate bearing capacity of suction anchors with static loads. It has not been reported how to calculate the bearing capacity of suction anchors under combined static and cyclic loads based on upper bound plasticity theory. An upper bound plasticity analysis method was presented to calculate the bearing capacity of suction anchors with taut mooring systems in soft clay under combined static and cyclic loads. Average shear stresses of soil elements due to the static load were first determined, which was based on the principle of static equilibrium for the method. Cyclic shear strengths of soil elements were further determined us- ing the relationship between the cyclic shear strength and the average shear stress associated with the number of cycles to failure so that the effects of cyclic loads on soils transfered to changes of strength. It was further assumed that the failure mode of suction anchors under combined static and cyclic loads was the same as that under static loads. The bearing capacity of the anchors could be calculated using cyclic shear strength by the upper bound plasticity analysis. In order to verify the reasonableness of the method, model tests of suction anchors were conducted under the condi- tion of lg. The results of model tests were predicted using the method. Predicted results were basically in agreement with those of model tests.