富水淤泥质软土地层盾构隧道管片受力特征研究

为研究富水淤泥质软土地层盾构隧道施工衬砌管片受力特征，依托佛山地铁2号线采用现场试验和数值模拟方法开展研究，根据地层条件现场布置3个测试断面，分别监测了管片土压力、管片轴力及管片纵向应力随推进环数的变化规律，进而采用ABAQUS数值方法建立分析模型，研究荷载条件下管片轴力和弯矩变化情况，并与现场测试结果进行对比。结果表明：①土压力随衬砌推进先急剧增大后慢慢减小，最后趋于稳定；但不同测试断面不同测点处土压力差异较大，拱顶部分受力相对较大，仰拱部分受力较小，对于富水软土盾构隧道施工以及运营应着重关注隧道拱顶部分受力，适当加强拱顶管片的强度。②随着管片拼装的进行，各管片轴力迅速增大，随着盾构进一步推进，管片轴力逐渐趋于稳定，但衬砌不同测点处轴力大小有所不同；隧道结构受力呈现不均匀状态，3个测试断面管片轴力区别较为明显，863环和887环受力相对较大，且管片受力极不均匀，875环受力较小，且受力相对均匀，875环隧道处于弱风化泥沙岩中，而863和887环均处于硬塑状黏土地层中，可见隧道施工中地层条件对隧道轴力影响较为显著。③随着推进环数的增加，不同测点处纵向应力先增大再减小，最后趋于稳定。④现场试验和数值计算所得管片内力基本接近，数值模拟能够较为真实地反映管片实际受力情况。

Mechanical Characteristic Investigation of Shield Tunnel Segment in Water-rich Mucky Soft Stratum

To study the mechanical characteristics of shield tunnel segments in a water-rich mucky soft stratum, field tests and numerical simulations were conducted for the Foshan Metro Line 2. Three test sections were arranged according to the stratum conditions; the soil pressure, axial force, and longitudinal stress of a pipe with a number of propulsion rings were monitored. Then, an ABAQUS numerical analytical model was established, and the axial force and bending moment of the segment under load were studied. Following this, the numerical results were compared with the field test results. The results are as follows:① The earth pressure increases sharply with the advancement of the lining, then decreases slowly, and finally tends to be stable. However, the soil pressures at different points in different sections are quite different, the stress in the vault is relatively high, and the force in the invert arch is low. For the construction and operation of the shield tunnel in water-rich mucky soft stratum, the stress in the vault should be investigated closely, and the vault should be strengthened properly. ② The axial force of each segment increases rapidly as segment assembly progresses. With the further advancement of shield tunneling, the axial force of the segment tends to stabilize gradually; however, the magnitudes of the axial forces differ at different measurement points in the lining. The stress of the tunnel structure is uneven, and the axial force of the three test sections are quite different. The difference in the results of the 863 and 887 rings is relatively obvious. The force of the tube is not uniform, and the force of the 875 ring is smaller and relatively uniform. The 875 ring tunnel is in weakly weathered mud sand rock, and the 863 and 887 rings are in hard plastic clay stratum; thus, the stratum conditions have a more obvious influence on the axial force of the tunnel. ③ As the number of advancing rings increases, the longitudinal stresses at different measurement points increase first and then decrease. ④ The results of the internal forces of the segments obtained from field tests and numerical calculations are similar, and the numerical simulations are more realistic in terms of the actual responses of the segments.