水平荷载作用下张力腿平台吸力式基础的物理模拟

Physical modelling of suction foundations of TLPs under horizontal loads

介绍了张力腿平台吸力式基础在水平静载和循环动荷载作用下的离心模型试验。通过水平静载离心试验获得了基础的水平承载力。利用电磁式激振器模拟动荷载,研究在动荷载作用下吸力式基础的动力响应,并比较了荷载强度和基础刚度对基础动力响应的影响。分析结果表明,在动荷载作用下,泥面下1～2 m深度内土体中孔压最大。当动荷载强度超过临界承载力时,基础周围土体有非常强的液化可能性。综合孔压变化和基础沉降规律分析基础有两种可能的破坏模式:振动最初1～2 h内的液化破坏和长时间激振后沉降过大引发的问题。将单桶连接成多桶基础,增大基础刚度,在相同动载强度下,周围孔压增长和激振沉降均小于承受相同荷载条件的单桶基础。

The results of centrifuge model tests on the behavior of suction bucket foundations of a TLP under static and cyclic horizontal loads were presented. The ice-sheet induced structural vibration was simulated as an equivalent cyclic lateral load by an electro-magnetic actuator. The effects of the load intensity and the geometry of the foundation were investigated. The static horizontal bearing capacity of the foundation was determined by the static tests. It was indicated by the results of dynamic centrifuge tests that the excess pore water pressure reached the highest value within a depth of 1～2 m below the mud line. The pore pressures and the induced settlement increased with the increase of the amplitudes of the cyclic loadings. Two failure modes might be involved： liquefaction in the early excitation and settlement induced problem after long term excitation. However, with the increase of stiffness of the bucket foundation, the pore pressures and the induced settlement decreased.