为解决地下水位随季节升降变化时隧道开挖对邻近桩基的长期影响难题,通过三维离心模型试验,研究了地下水位循环变化时隧道对群桩的长期影响。主要分析水位循环变化时地表长期沉降、桩顶长期附加沉降、桩身长期附加弯矩和附加轴力的变化规律。试验结果表明:在隧道附近,地下水位循环变化尤其是降水对地表长期沉降影响更为明显。地表长期附加沉降随着地下水位循环次数增加而增大,且呈衰减式变形,即使经过3次水位升降循环也不能稳定;桩基长期附加沉降显著,其附加沉降量占总沉降量的50%以上;前、后桩的长期附加轴力基本为正值,桩总轴力增加,对既有受压桩极为不利,附加轴力拐点位置及最大值有所区别;经过3次地下水位循环变化后,前、后桩桩身弯矩反弯点个数减少,但桩身最大附加弯矩均明显变大,当达到极限弯矩,桩身出现塑性铰,这对穿越厚软弱层地基中的既有受压柔性桩极为危险。 In order to solve the long-term impact of tunnel excavation on adjacent pile foundations when the groundwater level changes with the seasons, the long-term influence of tunnel on pile groups is studied by three-dimensional centrifugal model test. Mainly analyze the long-term surface subsidence, long-term additional settlement of pile top, long-term additional bending moment of pile and additional axial force when the water level changes cyclically. The test results show that: in the vicinity of the tunnel, the cyclic changes of groundwater level, especially the precipitation, have a more obvious impact on the long-term settlement of the surface. The long-term additional settlement of the ground surface increases with the increase of the number of groundwater level cycles and shows an attenuated deformation, which can not be stabilized even after three times of water level rise and fall cycles. The long-term additional settlement of the pile foundation is significant and the additional settlement accounts for 50% ; The long-term additional axial force of the pile before and after the pile is basically positive, the total axial force of the pile increases, which is extremely unfavorable to the existing pile, the position and maximum value of the point of inflection of additional axial force are different; after three times of cyclic variation of the groundwater level After the front and rear piles, the number of bending points decreases, but the maximum additional bending moment of the piles increases obviously. When the ultimate bending moment is reached, the plastic hinge appears in the piles. Both flexible pressure pile is extremely dangerous.