结构下穿隧道地表沉降变形解析预测方法

Analytical Prediction Method of Ground Settlement Deformation of Tunnel Under Structure

摘要:

考虑地表建(构)筑物结构荷载作用下隧道开挖引起的地表沉降,将结构荷载等效简化为均布荷载,分别针对半空间结构荷载作用下围岩的变形场与半空间无荷载下埋隧洞建立解析模型,根据两个模型的计算结果预测结构下穿隧道条件下的地表沉降变形。对于半空间结构荷载作用下围岩的变形场,通过对地表施加的均布荷载进行积分,得到半空间的应力分布解答式,进而计算得到半空间由建筑物荷载引起的位移场分布。对于半空间无荷载下埋隧洞,基于浅埋隧道问题的简化形式,采用Airy应力函数得到半无限空间中隧道开挖引起的位移场表达式。在两个解答的基础上,得到地表建筑物荷载影响下下穿隧道引起地表沉降变形的解析解。通过该解析预测结构荷载与隧道开挖共同作用下的地表沉降特征,并绘制沉降曲线分析地表沉降规律,将理论计算的沉降变形与实测沉降数据进行比较。结果显示,计算值与实测值相对误差为3.9%,证明计算模型能够较好描述建筑物荷载和隧道开挖的耦合效应,验证了计算模型的准确性与适用性。

Abstract:

The analytical prediction method for ground settlement deformation of underground tunnels considering the surface building (structure) load-induced ground settlement due to tunnel excavation takes the structural load as an equivalent distributed load. It establishes analytical models for the deformation field of surrounding rock under the action of half-space structural load and the buried tunnel under the condition of no load in the half-space. Based on the calculation results of the two models, the ground settlement deformation under the condition of structure-underpass tunnels is predicted. For the deformation field of the surrounding rock under the action of the half-space structural load, the integral of the uniformly distributed force applied to the surface is used to obtain the stress distribution formula of the half-space, and then the displacement field distribution caused by the building load in the half-space is calculated. For the buried tunnel under the condition of no load in the half-space, the Airy stress function is used to obtain the displacement field expression of the tunnel excavation in the semi-infinite space based on the simplified form of the shallow-buried tunnel problem. On the basis of the two solutions, the analytical solution for the ground settlement deformation caused by the underpass tunnel under the influence of surface building loads is obtained. Through this analytical prediction, the ground settlement characteristics under the combined action of structural load and tunnel excavation are analyzed, and the settlement curve is drawn to analyze the surface settlement pattern. The calculated settlement deformation and the measured settlement data are compared, and the result shows that the relative error between the calculated value and the measured value is 3.9%, which proves that the calculation model can well describe the coupling effect of building load and tunnel excavation, and verifies the accuracy and applicability of the calculation model.