基于现场测试的复合地层盾构隧道荷载反演分析

Inversion Analysis of Shield Tunnel Load in Composite Strata Based on Field Tests

[目的]当隧道穿越横向复合地层时,荷载模式尚不明确,最终内力设计值往往与实际值存在偏差,因此有必要研究上软下硬复合地层中,地铁盾构隧道管片与土体的相互作用关系。[方法]以深圳地铁13号线留仙洞站—百旺港大站盾构穿越混合花岗岩区段为例,分析主体结构的内力情况,根据管片内力稳定后的现场实测值,选取待反演参数,定义优化目标函数。采用QPSO(量子粒子群)算法优化荷载参数,反演分析上软下硬地层中荷载的合理参数取值和具体受荷情况。[结果及结论]相比于TB 10003—2016《铁路隧道设计规范》中的取值,通过QPSO算法反演计算得到的荷载参数更适用于上软下硬地层,所计算出的内力分布形式较为接近实际情况,验证了所提分析方法的可行性与合理性。针对上软下硬的复合地层,隧道上覆荷载可取塌落拱高度计算,下层硬岩段侧压力系数应对地勘值进行适当放大。

[Objective]Due to the unclear load pattern,the final internal force design value often deviates from the actual value when a tunnel crosses transverse composite strata.Therefore,it is necessary to study the interaction between the metro shield tunnel segments and the soil in composite strata with soft upper layers and hard lower layers.[Method]Taking the Liuxiandong Station to Baiwang HKU Station shield tunnel crossing the mixed granite interval on Shenzhen Metro Line 13 as an example,the internal force situation of the main structure is analyzed.Based on the field-measured values after the segment internal force stabilizes,parameters for the inversion analysis are selected,and an optimization objective function is defined.The QPSO(quantum particle swarm optimization)algorithm is used to optimize the load parameters,and the reasonable parameter values and specific loading conditions in the upper-soft and lower-hard strata are obtained through inversion analysis.[Result&Conclusion]Compared with the values in TB 10003-2016 Code for Design of Railway Tunnels,the load parameters obtained through QPSO algorithm inversion calculation are more suitable for the upper-soft and lower-hard strata.The calculated internal force distribution is more similar to the actual situation,verifying the feasibility and rationality of the proposed analysis method.For composite strata with upper-soft and lower-hard layers,the tunnel overburden load can be calculated using the collapse arch height,and the lateral pressure coefficient of the lower hard rock section should be appropriately amplified for geological survey values.