考虑土拱效应的盾构隧道施工地表沉降预测

    PREDICTION OF GROUND SETTLEMENT IN SHIELD TUNNEL CONSTRUCTION CONSIDERING SOIL ARCHING EFFECT

    • 摘要: 城市地铁盾构隧道施工时,其上覆土体会产生应力转移和位移传递,为准确预测深埋盾构隧道施工过程中引起的地表沉降,基于能量法考虑“土拱效应”影响下的地层损失计算模型,开展了盾构施工地表沉降预测方法研究。首先,综合考虑隧道施工方法及“土拱效应”等因素,对Loganathan公式进行优化改进,采用Terzaghi理论计算土拱作用下的土体回弹变形,建立考虑土拱效应的圆形盾构隧道施工地表沉降预测模型;其次,基于弹性Maxwell-Betti功互换定理,考虑圆形盾构隧道衬砌支护作用,通过构建两组不同受力状态下的弹性力学模型计算模型,推导出能量法理论下隧道施工引起的地层损失理论解析式;最后,针对5个典型盾构隧道工程案例进行对比研究和预测分析。结果表明:考虑土拱效应的预测方法更加有效,预测结果更接近实际监测沉降值,验证了该方法在盾构隧道工程中具有较好的适应性和可靠性。

       

      Abstract: During the construction of an urban subway shield tunnel,the overlying soil will experience stress transfer and displacement transfer. To accurately predict the ground settlement caused by the construction of a shield tunnel,based on the calculation model of ground loss under the influence of the "soil arching effect" in the energy method,research on the prediction method of surface settlement of shield construction is carried out. First,the Loganathan formula is optimized and improved by comprehensively considering the tunnel construction method,the "soil arching effect," and other factors. The rebound deformation of the soil mass under the action of soil arching is calculated by Terzaghi theory,and a prediction model of ground settlement for circular shield tunnel construction considering the soil arching effect is established. Second,based on the elastic Maxwell-Betti work exchange theorem and considering the support function of circular shield tunnel lining,the theoretical analytical formula of formation loss caused by tunnel construction under the energy method theory is derived by constructing two groups of elasticity mechanical model calculation models under different stress conditions. Finally,five typical shield tunnel engineering cases are compared and forecasted. The results show that the forecasting method considering the soil arching effect is more effective and that the forecasting result is closer to the actual monitoring settlement value,which verifies that the method has better adaptability and reliability in shield tunnel engineering.

       

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