沿深度强度增加软土中吸力锚循环承载力模型试验

Model Tests on the Cyclic Bearing Capacity of Suction Anchors in Soft Clay with Increasing Strength along Depth

摘要:

采用分层底部真空预压技术,在模型试验箱内制备强度沿深度增加的模型试验土层;进而利用自行开发的电动伺服加载装置,在荷载控制方式下,针对水平破坏模式,进行两种直径的吸力锚在最佳系泊点受倾斜方向静荷载与循环荷载共同作用下的承载力模型试验。试验结果表明,循环荷载作用过程中锚的循环变形没有明显增加,导致锚破坏的是循环累积变形。强度沿深度增加软土和均一强度软土中吸力锚循环承载力的相对变化规律一致,当循环破坏次数为100时,循环承载力是静承载力的90%左右;当循环破坏次数增加至2000时,循环承载力减小至静承载力的70%左右。锚径的变化只影响循环承载力的大小,不影响其相对变化。强度沿深度增加土层中的吸力锚,其循环荷载下竖向阻力弱化程度大于水平阻力弱化程度,这与均一强度土层中吸力锚受循环荷载作用时的性态一致。

Abstract:

A model test stratum with increasing strength along depth was prepared in a tank using the multilayer vacuum preloading method at the bottom. Bearing capacity model tests were conducted for suction anchors with two diameters and subjected to inclined static and cyclic loads at the optimal loading point using an electric servo loading apparatus developed by the authors for the lateral failure mode. Model test results showed that the cyclic displacement of the anchor did not obviously increase with the increase of the number of cycles during cyclic loads, and the failure of anchors was attributed to the cyclic cumulative displacements. The relative variation of cyclic bearing capacity for suction anchors in soft clay with increasing strength along depth was consistent with that of suction anchors in soft clay with uniform strength along depth. The cyclic bearing capacity was approximately 90% of the static bearing capacity when the number of cycles was 100, and the cyclic bearing capacity decreased to approximately 70% of the static bearing capacity when the number of cycles was increased to 2000. The variation of anchor diameter only changed the absolute cyclic bearing capacity, and did not affect the relative variation of the cyclic bearing capacity. The degradation of the vertical resistance was larger than that of the lateral resistance for suction anchors in soft clay with increasing strength along depth under cyclic loads, which was the same as that observed for suction anchors in soft clay with uniform strength along depth.