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创新研发了复合配筋混凝土预制方桩,通过施加预应力提高桩身的抗裂性能,配置非预应力钢筋增强桩身的抗弯承载力和延性,采用实心而非空心截面且合理配置箍筋提高桩身的抗剪性能。对3种常用规格共9根方桩试件进行足尺度抗剪性能试验,对比研究预应力和非预应力混凝土预制方桩在抗裂性能、抗剪承载力、变形性能及破坏特征等方面的差异。结果表明:施加预应力可显著提高混凝土预制方桩试件斜截面的开裂剪力,限制并延缓桩身裂缝的发展,提高方桩的极限抗剪承载力,降低斜截面抗剪破坏的变形能力;方桩试件的极限抗剪承载力试验值较GB 13476—2009《先张法预应力混凝土管桩》推荐算式的计算值大50%以上;试件破坏形式有两种:斜截面抗剪破坏和正截面抗弯破坏。因此,此新型预制方桩能够有效解决预应力混凝土管桩水平承载力低、普通混凝土预制方桩抗裂性能差的问题。
Innovative research and development of composite reinforced concrete prefabricated square piles, by applying prestress to improve the crack resistance of the pile body, the configuration of non-prestressed reinforced piles to enhance the flexural capacity and ductility of the pile, the solid rather than the hollow section and the rational allocation of stirrups Improve the shear resistance of the pile body. Three kinds of common specifications of a total of 9 square pile specimens were tested on the full scale shear strength, comparative study of prestressed and non-prestressed concrete precast square pile in the anti-cracking performance, shear capacity, deformation and failure characteristics difference. The results show that prestressing can significantly increase the cracked shear strength of precast square piles, limit and delay the development of pile cracks, increase the ultimate bearing capacity of square piles and reduce the deformation capacity ; The ultimate shear capacity of the test specimens is 50% greater than the recommended value of the pre-tensioned prestressed concrete pipe pile of GB 13476-2009; there are two types of specimen failure modes: Vandal and cross-section bending damage. Therefore, the new prefabricated square pile can effectively solve the problem of low horizontal bearing capacity of prestressed concrete pipe piles and poor anti-cracking performance of ordinary concrete square piles.