考虑邻近建筑物影响的内撑式排桩基坑支护局部破坏研究

基坑开挖与周围环境相互影响，而邻近建筑物对基坑支护体系局部破坏的影响鲜有研究。通过内撑式排桩支护砂土基坑模型试验，研究了坑外有、无建筑物两种情况下基坑开挖、支撑局部破坏和桩后砂土渗漏对内撑式排桩基坑支护体系受力及变形性能的影响。试验结果表明：受邻近建筑物的影响，随基坑逐渐开挖，平行于邻近建筑物长边的支护桩桩顶水平位移增大，而垂直于邻近建筑物长边的支护桩桩顶水平位移减小，同时基坑中部内支撑轴力明显增大，角撑次之，边撑反而减小；邻近建筑物对平行于建筑物长边的支护桩桩身弯矩及反弯点影响较大，而对垂直于建筑物长边的支护桩桩身弯矩影响较小；局部内支撑破坏引起的坑外地面沉降较小，而内支撑连续破坏导致坑外地面产生显著沉降，影响范围为0.12~0.23倍开挖深度，同时临近的未失效支撑轴力显著增大，易引发连续破坏；邻近建筑物对平行于建筑物长边的支护桩桩身弯矩影响较大，对垂直于建筑物长边的支护桩桩身弯矩影响较小。当桩后砂土出现渗漏时，对平行于邻近建筑物长边的支护桩影响更为明显。

Partial failure behaviors of internal retaining pile row system considering the influence of adjacent buildings

The interactions between the excavation and surrounding environment and the influence of adjacent buildings on partial failure of support system are rarely studied and reported. Here, we studied the influence of excavation, partial failure of support and leakage of sandy soil behind the pile on the deformation coordination of the foundation pit and supporting system using model test of a foundation pit supported by internal retaining pile row system with and without adjacent buildings. The results show that affected by neighboring buildings, the horizontal displacement of the retaining pile parallel to the long side of the adjacent building increases with the excavation of the foundation pit, whereas that vertical to the adjacent building decreases. The axial force of the middle internal support increases greatly, followed by the angular support, while the side support decreases. The bending moment of the retaining pile parallel to the long side of the adjacent building increases, and the reverse bending point moves up, while that vertical to the adjacent building is quite the opposite. The ground settlement outside the pit caused by partial support failure is small, whereas that caused by continuous failure of the internal support is significant, and the influence range is 0.12-0.23 times of the excavation depth. The axial force of the adjacent intact support increases significantly, which can readily lead to progressive failure. The influence on the bending moment of retaining pile parallel to the long side of the building is greater than that vertical to the adjacent building. When the sand behind the pile leaks, the retaining pile parallel to the long side of the adjacent building decreases more significantly.