粉砂地层节制闸基坑注浆加固效果数值模拟研究

Numerical Simulation Study on Grouting Reinforcement Effect of Foundation Pit in Silt Stratum

以某粉砂地层深基坑为研究对象,采用FLAC3D计算并分析水闸基坑底采用注浆加固的效果,并将模拟结果与实测结果进行对比分析。结果表明:①基坑在开挖过程中,坑内地下水位线迅速降低,而坑外保持不变,表明施工过程中所采用的地连墙止水效果良好,可以阻止坑外地下水向坑内渗流;②基坑开挖过程中,坑外地表最大沉降点在距坑壁10m左右范围内,开挖的影响范围为1倍开挖深度。此外,采用注浆加固可以显著减小坑外地表沉降变形;③地连墙的水平位移表现为中间大、两端小的抛物线形态,且地连墙位移随开挖深度增大而增大,最大位移出现在12m位置。注浆加固后,地连墙的水平位移大大减小,当加固土体弹性模量分别为50、100和200MPa时,地连墙最大水平位移为27、24和22mm。最大水平位移减小55%~65%。

Taking a deep foundation pit in a silt stratum as the research object,FLAC3D is used to calculate the effect of grouting reinforcement at the bottom of the foundation pit,and the simulation results are compared with the measured results.The results show that:①The excavation process of the foundation pit zone,the groundwater level in the pit decreases rapidly,but remains unchanged outside the pit,which proves that the ground connection wall used in the construction process has a good water-stop effect and can prevent the seepage of groundwater outside the pit into the pit.②During the excavation of the foundation pit,the maximum subsidence point of the surface outside the pit is within about 10m from the pit wall,and the influence range of excavation is 1 times the excavation depth.In addition,the use of grouting reinforcement can significantly reduce the surface settlement deformation outside the pit.③The horizontal displacement of the ground connecting wall shows a parabolic shape that is large in the middle and small at both ends,and the displacement of the ground connecting wall increases with the increase of the excavation depth increase,and the maximum displacement occurs at the 12m position.After grouting reinforcement,the horizontal displacement of the ground connecting wall is greatly reduced.When the elastic modulus of the reinforced soil is 50、100 and 200MPa,the maximum horizontal displacement of the ground connecting wall is 27、24 and 22mm.