为了降低海底隧道施工风险，确保隧道施工顺利穿越海底几处风化深槽和风化囊区域，解决难以获得隧道围岩力学参数的技术难题，采用位移反分析方法建立了动态反演预测模型；作为比较，还简单介绍了弹塑性反演的一种全局优化方法。根据隧道典型断面实际监控量测的围岩拱顶沉降量和周边收敛位移量，结合先行服务隧道揭露的水文地质情况，进行优化反演分析，得到该类围岩初期支护后的等效弹性模量和等效侧压力系数。在相应的同类地质条件下，对后续将开挖的左、右主洞围岩采用边界元法进行正演数值计算，使之能为主洞施工方案比选以及支护设计参数调整与修正提供定量依据，做到信息化动态设计与施工。工程实例分析表明，利用正算反演分析法得出的围岩等效力学参数是可靠的，可据此对类似地质条件下主隧道围岩进行正演计算分析，预测主洞围岩的变形破坏模式，判断其围岩稳定性。位移反分析法是隧道施工变形理论预测分析与工程实际相联系的有效平台，为工程设计施工技术决策提供了一种切实有效的途径。

For reducing the construction risk of undersea tunnel, insuring the tunnel to smoothly pass through each weathering zone, and resolving the technical difficulties to obtain rock mechanical parameters, the dynamic back prediction model was established based on the displacement back analysis. As a comparison, an overall optimization method on elastoplastic back-analysis is briefly presented. Combining the hydrogeology exposed by advanced service tunnel, back analysis was carried out on the basis of the vault settlement and around convergence displacement by practical monitoring measurement. Then, the mechanical parameters would be obtained; that is, equivalent elastic modulus and confinement pressure coefficient of surrounding rock after primary support. Furthermore, in the similar geological conditions, boundary element method was used to normally simulate left and right main tunnels immediately after face advance and primary anchor bolt-shotcrete support. The normal calculation results could provide quantitative basis for comparison and selection of construction schemes of main tunnel, and adjustment and correction of support parameters of main tunnel. It realized the dynamic information design and construction. The analysis of engineering example indicates: it is reliable to obtain the equivalent mechanical parameters of surrounding rock by displacement back analysis. In similar geological conditions, the equivalent mechanical parameters can be used for normal calculation of main tunnels; furthermore, to forecast their deformations and failure modes, and estimate their surrounding rock stability. Displacement back analysis is a bridge which associates theoretical analysis with engineering during tunnel construction, and supplies a practical way for engineering design, construction and decision-making.