建议了一种利用软土不排水循环强度,评价静荷载与循环荷载共同作用下软土中吸力锚承载力的拟静力弹塑性有限元方法。该方法首先依据软土的不排水静强度,通过弹塑性有限元计算,确定平均系泊荷载作用下土体单元的八面体平均剪应力,再据此确定与一定循环破坏次数对应的土单元循环强度;然后,按土单元循环强度再次通过弹塑性有限元计算,确定锚系泊点沿系泊方向的荷载位移曲线;最终由荷载位移曲线、按位移破坏标准确定锚的循环承载力。这一方法的特点是考虑了平均系泊荷载对软土循环强度、进而对静荷载与循环荷载共同作用下锚承载力的影响。为说明这一方法的可行性,进行了不同锚径、不同长径比、不同平均荷载、不同摩擦系数、不同加载方向、不同破坏模式条件下的软土中吸力锚循环承载力模型试验。利用拟静力有限元方法对模型试验结果进行了预测,预测结果比试验结果偏小,平均偏小不超过10%。模型试验结果还表明,软土中锚的归一化循环承载力随循环破坏次数的变化只取决于归一化平均荷载,可以忽略加载方向、锚的直径、锚外壁摩擦系数对归一化循环承载力变化关系的影响。若归一化平均荷载为0.5,当循环破坏次数为1000时,对于竖向破坏的锚,循环承载力大约为静承载力的75%;对于水平破坏的锚,循环承载力大约为静承载力的80%,这与已有的离心模型试验结果基本一致。 A pseudo-static elasto-plastic finite element method is proposed based on undrained cyclic strength of soft soil and the bearing capacity of suction anchor in soft soil under static and cyclic loads. Based on the undrained static strength of soft soil, the method calculates the average octahedral average shear stress of soil element under the influence of average mooring load through elastic-plastic finite element calculation, and then determines the earth element cycle corresponding to the number of cyclic damage Then, according to the cycle strength of soil unit, the load-displacement curve along mooring direction of anchor mooring point is determined again by the elasto-plastic finite element method. Finally, the cyclic load carrying capacity of anchor is determined according to the displacement displacement curve. The characteristic of this method is that the effect of average mooring load on the cyclic strength of soft soil, and then on the anchorage capacity of static load and cyclic load is considered. In order to demonstrate the feasibility of this method, model tests of cyclic loading of suction anchor in soft soil with different anchor diameters, different aspect ratios, different average loads, different friction coefficients, different loading directions and different failure modes were carried out. The results of the model test are predicted by the quasi-static finite element method. The predicted results are smaller than the experimental ones, and the average is less than 10%. The results of the model tests also show that the normal cyclic loading capacity of anchors in soft soil varies with the number of cyclic damages only by the normalized average load, and the loading direction, the diameter of the anchor and the friction coefficient of the anchor outer wall can be ignored. Influence of changing relationship of bearing capacity. If the normalized average load is 0.5, when the number of cyclic damage is 1000, the cyclic bearing capacity is about 75% of the static bearing capacity for the vertically damaged anchor; and for the horizontal damaged anchor, the cyclic bearing capacity is about the static bearing capacity Of the 80%, which is consistent with the existing centrifuge model test results.