【摘要】 施工不当或者侧向堆载、开挖常常导致桩身倾斜,扶正难度较大,且目前对倾斜桩复合地基的变形性状缺乏相关研究,其可能导致新的工程病害,基于此,设计模型箱和加载装置,对竖向重复加卸载下倾斜桩复合地基变形规律开展试验研究。结果表明:循环加载过程中,倾斜桩顶及其复合地基沉降和侧移均随荷载增大而增大,其增长率随荷载增大而增大、随加载次数增大而减小;卸载过程中,卸载初期的倾斜桩顶及其复合地基沉降和侧移变化不明显,最后1～2级低压力时才出现弹性变形;相同荷载作用下,桩顶沉降量随倾斜角增加而增大,倾斜桩存在"沉降临界倾斜角"(试验前3次加卸载循环其值为6°),随土体密实度提高而降低,倾斜角小于该临界值时,倾斜对桩的沉降影响不大,反之,桩顶沉降量随倾斜角增加而快速增大;倾斜桩存在"侧移临界倾斜角"(试验为9°),为侧移峰值对应倾斜角;倾斜角度小于该临界值时,桩顶侧移随倾斜角增大而增大,反之,桩顶侧移随倾斜角增大而减小,"侧移临界倾斜角"大于"沉降临界倾斜角";相同荷载作用下,倾斜桩复合地基的沉降大于倾斜桩沉降,而侧移比倾斜角6°桩大,比倾斜角12°桩小,桩身倾斜时,倾斜桩与复合地基的侧移量远比其沉降量小,但是侧移比沉降更为敏感。工程中,应尽量减少桩身倾斜,降低倾斜桩及其复合地基的沉降量和侧移量。更多还原

【Abstract】 Improper construction, lateral surcharge, or excavation often leads to the tilting of pile bodies and causes problems of centralizability; however, the deformation characteristics of inclined pile composite foundation is not fully understood and may lead to new engineering diseases. A model box and loading device were designed to study the deformation law of inclined pile composite foundation under vertical repeated loading and unloading. The results are as follows: During the process of cyclic loading, the settlement and lateral displacement of the inclined pile top and its composite foundation increase as the load increases. Moreover, its growth rate increases as the load increases and decreases as the loading time increases. During the process of cyclic unloading, the settlement and lateral displacement of the inclined pile top and its composite foundation at the initial stage of unloading are not apparent, and elastic deformation occurs only during the last one or two stages of low pressure. Under the same load, the settlement of the pile top increases with the increase in the tilt angle. The inclined pile has a "critical inclination angle for settlement(6° during one to three loading and unloading cycles for the test)" that decreases with the increase in soil compactness. When the inclination is less than the critical value, the settlement of the pile has negligible effect and the settlement increases rapidly with the increase in the angle of inclination when it is greater than the critical value. The inclined pile has a "critical inclination angle for lateral displacement(9° for the test)" that corresponds to the peak value of lateral displacement. When the tilt angle is less than the critical value, the pile top lateral displacement increases with the increase in tilt angle. When the angle of tilt is larger than the critical value, the pile top lateral displacement decreases with the increase in tilt angle. The "critical inclination angle for lateral displacement" is greater than the "critical inclination angle for settlement". Under the same load, the lateral displacement of the composite foundation with an inclined pile is larger than that of the 6° pile and smaller than that of the 12° pile, and the settlement is larger than that of any inclined pile. When the pile is inclined, the lateral displacement of both the inclined pile and the composite foundation is considerably smaller than the settlement, but the lateral displacement is more sensitive than the settlement. In engineering, the inclination angle of the pile should be reduced as far as possible, and the settlement and lateral displacement of the inclined pile and its composite foundation should be reduced.更多还原