为研究复杂地层条件下泥水压力对掌子面稳定性的影响，依托连续穿越全断面软弱地层、上软下硬地层以及全断面微风化岩层的妈湾海底大直径泥水盾构隧道，分别建立不同地层条件下掌子面稳定性分析三维数值模型，得到掌子面位移分布规律及极限支护应力比。此外，由于既有研究常采用矩形荷载模式对泥水压力进行简化，对比分析实际梯形荷载模式及简化矩形荷载模式对掌子面稳定性分析的差异。结果表明： 1）全断面软弱地层中掌子面位移分布呈现“中间均匀，两端分化”形态，上软下硬地层中自拱顶向拱底大致线性减小；  2）采用切线交汇法获得掌子面的极限支护应力比全断面软弱地层最大，上软下硬地层次之，全断面微风化岩层中最小； 3）掌子面在梯形荷载分布情况下上部土体位移远大于矩形荷载分布情况，且得到的极限支护应力比大于矩形荷载分布，计算中忽略泥水容重影响是不合理的。

A largediameter slurry shield used in Mawan subsea tunnel continuously crosses through fullface soft stratum, uppersoft and lowerhard strata, and fullface slightlyweathered rock stratum. To investigate the influence of slurry pressure of slurry shield on face stability under complex strata conditions, 3D numerical simulation models under different strata are established to obtain corresponding displacement distribution laws and ultimate minimum supportstress ratio of tunnel face. In addition, the rectangular load mode is often used to simplify the slurry pressure in previous researches, the differences between the actual trapezoidal load mode and the simplified rectangular load mode in the stability analysis of tunnel face are compared and analyzed. The results show the following. (1) In the case of fullface soft stratum, the displacement of the tunnel face is relatively uniform in the middle of tunnel face, while it is quite different at both ends, whereas in the uppersoft and lowerhard strata, the displacement decreases linearly from the arch crown to the bottom. (2) The maximum supportstress ratio of the tunnel face obtained by tangent intersection method is the largest in the fullface soft stratum, followed by that in uppersoft and lowerhard strata, and that in the fullface slightlyweathered rock stratum is the smallest. (3) In the case of trapezoidal load distribution, both the upper soil displacement and the obtained ultimate minimum support stress ratio are far larger than that of rectangular load distribution, indicating that it is unreasonable to ignore the influence of unit weight of slurry in calculation.