汽车荷载对河底小净距隧道二次衬砌受力性状的影响分析

Analysis of Influence of Vehicle Loads on Mechanics Properties of Secondary Lining of Tunnels with Small Clear Spacing at Bottom of River

针对国内罕见的采用矿山法开挖与复合式衬砌的河底浅埋小净距公路隧道,以浏阳河公路隧道工程为例,研究服役期洞内汽车荷载对这类特殊隧道二次衬砌受力性状的影响.首先,考虑到隧道施工过程对服役性能有影响,建立反映施工过程的三维渗流应力耦合数值模型;其次,对比初衬拱顶沉降的数值模拟结果与现场实测结果,验证了数值模型具有参考价值;最后,对比分析服役期汽车荷载为0 k Pa、10 k Pa、20 k Pa、30 k Pa共四种工况.结果表明:双洞靠近中夹岩侧二衬的竖向位移略大于远离中夹岩侧二衬的竖向位移;随着汽车荷载从无到有并且逐渐增大,双洞二衬的上浮量逐渐减小,双洞二衬的最大拉应力也逐渐减小,施加汽车荷载可以降低隧底较大水浮力的影响.

In view of the rare shallow buried highway tunnels with small clear spacing at bottom of river in China,which is excavated by mining method and with composite lining,the influence of vehicle loads in holes on mechanics properties of secondary lining of this kind of special tunnels during the service period was studied.First of all,considering the influence of tunnel’s construction process on service performance,a three-dimensional numerical model of seepage stress coupling reflecting the construction process was established.Secondly,the numerical simulation and field measurement’s results of the settlement of initial lining vault were compared,and it was verified that the numerical model has reference value.Finally,the four working conditions of vehicle loads in service period were compared and analyzed,which are 0 kPa,10 kPa,20 kPa and 30 kPa.The results show that the vertical displacement of secondary lining near the middle rock is slightly larger than that away from the middle rock.With the gradual increase of vehicle loads from scratch,the floating length of double hole’s secondary lining decreases gradually,the maximum tensile stress of double hole’s secondary lining also decreases gradually,application of vehicle loads can reduce the influence of large water buoyancy at tunnel bottom.