裙式吸力基础在层状土中沉贯的渗流数值分析

Numerical Analysis on Seepage During the Installation of the Skirted Suction Caisson in Layered Soil

针对一种新型吸力基础形式——裙式吸力基础,采用有限元方法,研究其在粘性土及层状土(上层砂土,下层粘性土)中,吸力沉贯时周围土体中渗流场及水力梯度分布规律。研究发现:在粘性土及层状土中,主桶内部土体等势线分布密集且斜率较小,外侧等势线分布稀疏且斜率较大;沉贯中水头损失主要集中在主桶内部。对于层状土中的沉贯,当基础穿越砂土进入粘性土层时,砂土中等势线分布变稀疏,水头损失变小;粘性土中等势线分布密集,水头损失增大。吸力沉贯过程中,水力梯度最大值出现在主桶端部。

Suction caissons are widely used in offshore engineering. This paper presents a finite element analysis for the installation of the novel skirted suction caisson in clay and layered soil（sand over clay）. It also investigates the distribution laws of equipotential lines and hydraulic gradient of the soil around the caisson under various penetration depths. Results show that in clay and layered soil, the distribution of equipotential lines within the main structure is dense and the slopes of equipotential lines become smaller, while in the soil out of the caisson,the distribution of equipotential lines is sparse and the slopes of equipotential lines are relatively larger. The head loss across the flow domain mainly takes place in the soil within the main structure. When the skirted suction caisson penetrates through sand into the layered soil, the distribution of equipotential lines in sand becomes sparser, with smaller head loss, just the opposite to those in clay. During the process of suction-assisted penetration,the maximum hydraulic gradient was observed at the tip of the main structure.