基于FLAC3D分析的地铁施工中基坑稳定性研究

Study on Stability of Foundation Pit in Subway Construction Based on FLAC3D Analysis

采用FLAC3D软件建立了地铁施工中基坑的三维计算模型,并对隧道掘进进行了模拟分析。结果表明,在盾构推进过程中,地铁施工中基坑最大沉降值和最大隆起值都分别出现在隧道顶部盾尾和隧道底部壁后注浆处,但是沉降值都呈现随着盾构推进逐渐增大的特征,而隆起值都呈现随着盾构推进而先增大后减小的特征。随着盾构推进的增加,沉降槽的宽度变化率减小、沉降则逐步增大;随着开挖面与监测点距离的增加,不同深度处的沉降量都呈现逐渐降低的趋势,且在相同监测点处,距离地表越深则最大沉降量越小;地铁施工中地表监测结果与FLAC3D模拟结果相吻合。采用FLAC3D软件可以对地铁施工中的基坑稳定性进行有效模拟与分析。

FLAC3D software is used to establish the three-dimensional calculation model of the foundation pit in the subway construction,and the simulation analysis of the tunnel excavation is carried out.The results show that the maximum settlement value and the maximum uplift value of the foundation pit in the process of shield tunneling appear in the tail of shield at the top of the tunnel and the grouting position behind the wall at the bottom of the tunnel respectively,but the settlement value shows the characteristics of increasing gradually with the advance of shield tunneling,while the uplift value shows the characteristics of increasing first and then decreasing with the advance of shield tunneling.With the increase of shield advance,the smaller the change rate of settlement groove width is,the larger the settlement will be;with the increase of the distance between the excavation face and the monitoring point,the settlement at different depths will gradually decrease,and at the same monitoring point,the order of settlement is Z=3M>z=9m>z=12m>z=15m;the results of ground surface monitoring in subway construction are consistent with the results of FLAC3D simulation.FLAC3D software can effectively simulate and analyze the stability of foundation pit in subway construction.