非对称异形基坑挡墙离心模型试验研究

Centrifugal model test on deformation of retaining wall in asymmetric shaped foundation pit

随着坑中坑一类基坑数量增多及内坑规模增大,因设计低估内坑影响造成的基坑事故时有发生,坑中坑问题成为一个亟待解决的岩石工程问题。以南京梅子洲过江通道超大型地下交通系统工程为背景,通过离心模型试验分析内外坑间距对内外坑围护墙土压力及变形的影响。研究结果表明:随着内外坑间距减小,开挖完成后中墙外侧土压力逐渐增大,始终大于静止土压力,中墙外侧底部土压力接近坑外静止土压力;随着内外坑间距减小,开挖完成后中墙顶部左侧水平位移及右墙最大水平位移均逐渐减小,始终向坑内方向变形;土压力的变化与围护墙的变形较为吻合。

With the increasing of pit-in-pits and the scale expansion of the inner pit,the support of pits-in-pit become an urgent problem to be solved for the frequent occurrence of pit accidents due to the underestimation to the inner pits impact in retailing structure design. In the case of Meizizhou Changjiang-cross tunnel in Nanjing,we analyze the impact of interval between internal and external pits on earth pressure and deformation of retailing structures separating and supporting the internal and external pits by centrifugal model test. The results show that with the decrease of interval,the outside earth pressure on the middle wall gradually increases after the excavation,maintaining above the static earth pressure throughout,and the outside earth pressure near the bottom of the middle wall is close to the static earth pressure of the outside pit; with the decrease of the interval,the horizontal displacement at the left top of the middle wall and the maximum horizontal displacement of the right wall decrease gradually,which is toward the inner side all the time. The variation of the earth pressure is in good agreement with the deformation of the retaining wall.