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盾构隧道施工邻近桥梁桩基已成为目前研究的热点问题。针对盾构施工参数取值在工程中的应用价值,利用三维弹塑性有限元分析了桩基引起地层的竖向附加应力,反推出了Geedes式中的桩端阻力、桩侧阻力分担桩顶荷载的比例系数与桩长的数学表达式,并将Geedes竖向附加应力影响范围与Randolph提出的影响半径对比分析后,给出了桩基影响区域和非影响区域的界定半径;基于支护压力、注浆压力的理论取值范围及单位长度上土体损失量等于沉降槽面积的条件,利用三维弹塑性有限元进行计算分析,给出了支护压力、注浆压力在桩基非影响区域内的建议取值和土体损失的计算表达式;基于桩基非影响区域内盾构施工参数的建议取值及桩基对地层产生的附加应力,给出了桩基影响区域内盾构施工参数建议取值的数学表达式。研究结果表明:工作面的土压力阻力选取工作面静止土压力合力,注浆压力选取1.1倍的隧道埋深处水土压力时,对地层的扰动较小。
The construction of shield tunnel near bridge pile foundation has become a hot issue in current research. In view of the application value of shield construction parameters in engineering, the vertical additional stress caused by pile foundation is analyzed by using three-dimensional elasto-plastic finite element method, and the pile end resistance in Geedes formula is deduced. The pile side resistance shares the load of pile top And the mathematical expression of the pile length, and after comparing the influence range of vertical additional stress of Geedes with the radius of influence proposed by Randolph, the defined radius of the affected area and non-affected area of pile is given. Based on the support pressure, The theoretical range of grouting pressure and the condition that soil loss per unit length is equal to the area of settling tank are calculated and analyzed by using three-dimensional elastic-plastic finite element method. The supporting pressure is given and the grouting pressure is within the non-influencing area of pile foundation And the calculation formula of soil loss. Based on the recommended values of the shield construction parameters in the non-affected area of pile foundation and the additional stress of the pile on the formation, the construction parameters of the shield in the affected area of the pile are given The suggested value of the mathematical expression. The results show that the earth pressure resistance of the working face selects the joint earth pressure of the working face and the water pressure of the tunnel buried depth of 1.1 times of the grouting pressure chooses the disturbance to the earth face.