急曲线电力盾构隧道侧穿桥桩扰动特性研究

Study on disturbance characteristics of sharp curve electric power shield tunnel passing alongside bridge piles

为探究急曲线电力盾构隧道施工对邻近桥梁桩基受力特性的影响,以转弯半径50 m的急曲线电力盾构隧道为例,建立不同水平净距下急曲线隧道侧穿桥桩的三维有限元模型,分析隧道和桥桩的水平净距对桩基变形和受力特性的影响。结果表明:数值模拟的地表沉降值与Peck公式理论值的计算相对误差在4%~19%之间,属于正常范围,说明数值计算结果是可靠的;当水平净距从3.6 m减小到1.2 m时,桩基的竖向变形值和横向变形值均增大,增率分别为143.24%和55.56%,同时最大轴力和最大弯矩分别增大了2.08倍和3.00倍;隧道埋深处曲线内侧的桩基附加弯矩最大,受力最不利,施工过程中应重点监测;墩柱在净距为1.2 m时的差异沉降值为0.32 mm,倾斜率为0.014%,均小于规范允许值。

In order to explore the influence of construction of sharp curve electric power shield tunnel on the mechanical properties of pile foundations of adjacent bridge,taking a sharp curve electric power shield tunnel with turning radius of 50 m as an example,the three-dimensional finite element models of sharp curve tunnels passing alongside bridge piles under different horizontal net distance were established.The influence of the horizontal net distance between tunnel and bridge pile on the deformation and stress characteristics of pile foundation was analyzed.The results show that the calculation relative error of the surface settlement value between the numerical simulation and the theoretical value of Peck formula is 4%-19%,which is in the normal range,indicating that the numerical calculation results are reliable.When the horizontal net distance decreases from 3.6 m to 1.2 m,the vertical and transverse deformation values of pile foundations increase,and the growth rates are 143.24%and 55.56%respectively.At the same time,the maximum axial force and maximum bending moment increase by 2.08 times and 3.00 times respectively.The maximum additional bending moment occurs in the pile foundations situated on the inner side of the curve at the buried depth of the tunnel,so the pile foundations bear the most unfavorable stress.Therefore,the pile foundations situated on the inner side of the curve should be well monitored in actual construction.When the net distance is 1.2 m,the differential settlement value and inclination rate of pier column are 0.32 mm and 0.014%respectively,which are less than the allowable specification value.