通过离心模型试验,研究沿海离岸深厚软基上大砂袋围堰的变形和失稳形态。改进模型中土工袋应变的测量方法,采用柔性胶黏贴高延展应变片,测试不同深度的大砂袋应变状态,分析土工袋的应力分布及其对大砂袋围堰稳定的影响。试验结果表明:(1)大砂袋具有加筋作用,限制了围堰的水平位移,整体性较好;(2)当地基中未打设塑料排水板时,围堰不均匀沉降明显,围堰坡脚处隆起土工布受拉,中心处沉降土工布受压,加设塑料排水板后,土工布受力增大,主要集中在坡脚处大砂袋,最大强度发挥水平约为86%;(3)塑料排水板的存在,有效地减少了软基的固结时间,均衡了地基的不均匀沉降,提高了软基在围堰施工过程中的强度,增强了大砂袋围堰的稳定性。 Through the centrifugal model test, the deformation and instability of the large sandbank cofferdam on offshore deep soft soil are studied. The method of measuring the geotextile strain in the model was improved. The strain gauge of the large sand bag at different depths was tested by flexible adhesive tapes. The stress distribution of the geotextile bag and its influence on the stability of the cofferdam were analyzed. The test results show that: (1) The large sand bag has the function of reinforcement, which limits the horizontal displacement of the cofferdam and the integrity is better; (2) When the plastic drainage board is not laid on the foundation, the uneven cofferdam settles obviously. At the foot of the weir, the geotextile was lifted at the foot of the slope, and the geotextile at the center was subsided. After the plastic drainage board was added, the geotextile force was increased. The geotextile mainly concentrated on the sand pocket at the foot of the slope, and the maximum intensity was about 86% ; (3) The existence of the plastic drainage board effectively reduces the consolidation time of the soft foundation, balances the uneven settlement of the foundation, improves the strength of the soft foundation during the construction of the cofferdam, and enhances the cofferdam of the large sand bag stability.