盾构隧道收敛变形倾角感知布设优化研究

Layout Optimization of Tilt Sensors for Convergence Monitoring in Shield Tunnel

为了实现采用倾角感知盾构隧道的水平收敛,通过传感器的优化布设,构建运营期盾构隧道收敛变形实时监测系统.考虑隧道拱顶埋深、接头抗弯刚度比、地层抗力系数、地层侧压力系数及地面超载等参数的作用,针对管片变形和管片接头的影响,采用解析方法提出基于倾角传感隧道收敛的计算方法,并利用误差反演算法得到该算法下最优安装位置.建立单环盾构隧道结构三维精细化数值模型,采用正交实验法得到25组工况的最优布设点,与解析方法结果进行对比验证.基于现场168天连续的监测实测数据,采用二乘法比较不同方法计算的水平收敛变化值与激光监测结果的差值平方和,进行现场验证.结果表明:对于软土地区盾构隧道典型断面,最优布设点在120°附近(以拱顶为0°),当地层信息缺失时,可选用120°位置布设倾角传感器,典型地层条件下,解析解得到的误差不超过4%,数值解分析误差不超过10%,现场监测计算误差小于10%.在现场安装条件受限情况下,给出不同地层工况条件的安装位置偏移方案及其误差修正方法.最后,分析倾角和激光监测对应的71组现场数据,相比于其他3种方法,提出的隧道水平收敛计算方法得到的结果最接近激光测量值,其差值平方和最小,稳定性最优,可作为现场监测有效手段.

To realize real-time convergence monitoring of operating shield tunnels,the layout scheme of wireless tilt sensors was optimized in this study.Under the interaction of tunnel depth,joint bending stiffness ratio,ground resistance ratio,lateral pressure coefficient,and ground overloading,considering the effect of segment and joint deformation,a new method for calculating the convergence of shield tunnel based on tilt sensors was proposed. Error back analysis was used to obtain the optimal installation position.A three-dimensional refined numerical model of single-ring shield tunnel was built to verify the analytical solution.Twenty-five groups of optimal layouts were obtained using orthogonal test.Moreover,several current convergence algorithms were presented and discussed. Field data for 168 days were analyzed using the square law,and the different sums of squares of the shield tunnel convergence sensed by different methods and the result monitored by laser range sensors were compared.The results show that the optimal layout position was around 120°(taking the position of crown as 0°)for the typical sections of Shanghai subway.If the information of local soil was not enough,the tile sensor was recommended to be fixed at 120°.In a typical condition,the error from the analytical method was less than 4%,and the error from the numerical method was less than 10%.In the field case,the error was less than 10%.If the field position was infeasible for installing the sensors,the offset scheme and its error correction method were given under different soil conditions. Seventy-one groups of field data from tilt sensors and laser range sensors were analyzed.The proposed method showed better agreement than three other methods.Its sum of squared difference was minimum,and its stability was suitable for field monitoring.