大埋深盾构隧道结构受力现场实测分析

Field Measurement and Analysis of Forces on Shield Tunnel Structure at Great Depth

以广佛环线东环隧道大源站—太和站工程项目为依托,通过开展大埋深盾构隧道结构内力现场测试,探究实际施工不同阶段管片内力的变化规律,并结合数值模拟对管片内力现场实测值与模拟值进行误差对比研究,分析施工因素对管片内力的主要影响位置及原因。结果表明:盾构施工过程中管片内力最大值出现在脱环后4~8环时的壁后填充阶段,最小值为拼装完成阶段,在盾尾脱环12环之后管片受力基本达到稳定阶段;管片内力实测值皆较大于模拟值,二者弯矩分布规律相似,轴力分布有一定差异,豆砾石充填可使实际轴力沿环向分布更均匀;实测值与模拟值最大相对误差约为40%,出现在拱顶及拱底区域,拱腰处相对误差较小;大埋深盾构隧道掘进时,壁后填充及稳定阶段管片内力的主要影响因素为豆砾石充填及围岩蠕变等。

In this study,based on the Dayuan Station-Taihe Station project of the East Ring Tunnel of the Guangfo Ring Line,field test of internal forces on the shield tunnel structure at great depth is performed to explore the change law of the internal forces on the segments during different phases of actual construction.By combining with numerical simulation,a comparative study is conducted on the error between the on-site measured values and simulated values of internal forces on the segments,and the main areas of segments where the internal forces are influenced by con⁃struction factors and the related causes are analyzed.The results show that during shield tunnelling,the maximum internal force of the segment occurs during the filling phase behind the wall after the detachment of 4-8 lining rings,and the minimum value occurs during the completion phase of segment assembly.After the detachment of 12 lining rings at the shield tail,the forces on the segment become basically stable.The measured values of internal forces in the segment are greater than the simulated values,and the distribution laws of measured and simulated bending mo⁃ments are similar.There are certain differences in the distribution of their axial forces,and filling with bean gravel can make the actual axial force more evenly distributed along the circumferential direction.The maximum relative error between the measured value and the simulated value is about 40%,which occurs in the tunnel crown and bottom areas,while the relative error at the arch waist is relatively small.In construction of shield tunnel at great depth,main influencing factors on internal forces of the segment in filling behind the wall and during stabilization phase are filling of bean gravel and creep of surrounding rock.