水下盾构隧道接缝渗漏规律的模型试验研究

Model test on joint leakage in underwater shield tunnels

为研究水下盾构隧道接缝处的渗漏规律,设计一套恒水压下盾构隧道渗漏的模型试验装置,对隧道拼装方式、漏缝宽度及漏缝位置不同时的漏水漏砂规律进行试验研究,揭示渗漏对漏缝周围土体受力与变形的影响。试验结果表明:临界缝宽几乎不受漏缝位置的影响,临界缝宽下漏水量不收敛且与渗漏方向有关,隧道拱腰处接缝的漏水速率约为拱顶处的2倍;而漏砂量在4min内均已收敛且与应力土拱的形成有关,隧道拱脚处漏缝旁的土压力增量最大,应力土拱最难稳定,其漏砂量约为拱顶处的3倍。漏砂的特征粒径从原始级配开始逐渐降低,最终更小的颗粒被吸附在大颗粒骨架周围不再漏出,漏缝旁的土压力增幅约60%,且土压力增量与渗漏砂–水质量比正相关。拱脚漏缝渗漏时土体表层沉降最显著,错缝拼装渗漏时表层沉降的平均影响范围更广。

In order to investigate the leakage law of underwater shield tunnel joints,a set of model test device was designed to observe the leakage process of shield tunnels under constant water pressure,and tests for the leakage law with different assembly patterns,leak widths and locations were carried out.The influence of the leakage on soil stress and deformation around the leak was also revealed.The experimental results show that the critical width of the leak is almost unaffected by the leak location.The water leakage under the critical width is non-convergent and related to the leakage direction.The leakage rate at the tunnel hance is about twice that at the tunnel vault.However,the sand leakage of all leaks is convergent within 4 min and is related to the formation of the soil stress arch.The increment of the soil pressure around the leak at the arch foot of the tunnel is the largest,the soil stress arch is the most difficult to stabilize,and the amount of sand leakage at the arch foot is about three times of that at the tunnel vault.The characteristic particle size of sand leakage decreases gradually from the original gradation,and eventually smaller particles are absorbed on the skeleton of large particles and no longer leak out.The soil pressure around all leaks increases by approximately 60%,and the increment of the soil pressure is positively related to the leaking sand-water mass ratio.The surface settlement is the most obvious when the tunnel arch foot is leaking,and the average influence range of the surface settlement is wider when the staggered pattern assembly tunnel is leaking.