土压平衡盾构开挖面压力取值及对地表沉降的影响

Study on Range of Pressure on Tunnel Face of Earth Pressure Balanced Shield and Its Influence on Ground Surface Settlement

土压平衡盾构广泛应用于地铁隧道施工中,其施工过程产生的地表沉降及相关问题直接影响隧道施工安全。以成都地铁3号线某区间盾构隧道工程为例,应用理论方法计算盾构开挖面压力取值范围。结合工程地质条件、施工参数、不同开挖面压力和地层损失率,利用嵌入了土应力路径本构模型的ABAQUS软件进行盾构开挖三维模拟,得到了卵石地层盾构施工引起的地表沉降规律,并通过与现场地表沉降监测结果对比,验证了此模型的合理性,确定了合理的开挖面压力取值范围。最后,进一步分析了实际盾构施工开挖面压力值与地表沉降值之间的规律,评价施工时设定的开挖面压力值的优劣。

EPB shield is widely used in the construction of Metro tunnels.Ground surface settlement induced by shield tunneling directly affects the safety of the tunnel construction.The authors use different theoretical methods to calculate the range of the pressure on the tunnel face in a shield-bored tunnel on Line 3 of Chengdu Metro.The shield boring process with different ground loss ratios and different pressures on the tunnel face is simulated by ABAQUS software embedded by constitutive model of soil stress path.The law of ground surface settlement induced by shield boring in gravel strata is obtained.The comparison and contrast between the ground surface settlement measured in the field and that obtained by means of theoretical calculations proves that the constitutive model adopted is rational.Proper range of the pressure on the tunnel face is determined.In addition,the relationship between the pressure on the tunnel face and the ground loss ratio is investigated and summarized so as to provide reference for similar projects in the future.