淤泥层中沉管隧道基础形式选型及沉降数值分析

Foundation Type Selection and Settlement Analysis of Immersed Tunnel in Silt Layer

为探究不同基础施工方案对沉管隧道纵横断面的沉降影响,以广州市南沙区拟采用沉管隧道的过江方案为例,针对该地区淤泥层不同厚度分别提出换填、抛石挤淤、挤密砂桩、水泥搅拌桩和PHC桩5种沉管铺设基础设计方案,并采用Plaxis 2D软件对不同方案下的沉管隧道纵横断面进行数值模拟,尤其针对不同相邻地基工况,采用换填+砂桩、抛石+砂桩2种典型组合方案沉降进行分析。结果表明,5种方案下的沉管隧道纵横断面沉降变形规律较为一致,沉降值均满足设计规范要求;2种不同工况组合下的沉降值也满足要求,提出适宜南沙地区的沉管隧道铺设方案。

To investigate the influence of different foundation construction schemes on the settlement of the cross section and longitudinal section of the immersed tube tunnel,this paper takes the proposed immersed tube tunnel crossing scheme in Nansha District,Guangzhou City as an example,and proposes five different foundation design schemes for the immersed tube laying in terms of different thickness of silt seam in the area,namely,replacement filling,stone throwing and silt squeezing,compacted sand pile,cement mixing pile and PHC pile.Based on Plaxis 2D software,the longitudinal and cross-sectional sections of the immersed tube tunnel under different schemes were numerically simulated,and the settlement of two typical combinations of different foundation adjacent conditions,namely,replacement fill+sand pile and rock throwing+sand pile,were analyzed.The results show that the settlement and deformation patterns of the longitudinal and transverse sections of the immersed tube tunnel under the five scenarios are consistent,and the settlements obtained meet the design requirements,and the settlement under different combinations of working conditions also meet the requirements.Finally,a suitable solution for laying of immersed tube tunnel in Nansha area is proposed.