【作者】 李文杰；

【导师】 刘畅； 刘永超；

【作者基本信息】 天津大学 ， 建筑与土木工程（专业学位）， 2016， 硕士

【摘要】 预应力混凝土管桩作为预制桩的一种可靠桩型,具有单桩承载力高、质量可靠、节能环保、施工速度快、经济效益好等优点,在工程建设中广泛应用。自上海莲花河畔景苑7号楼整体倾覆事件后,国内开始重视预应力混凝土管桩,一些地区对预应力混凝土管桩在不同土层中的应用做了相应的限制,以保证预应力混凝土管桩在水平地震作用下的安全性。但是,由于预应力混凝土管桩本身的特殊工程性质以及预应力混凝土管桩基础抗震作用机理的复杂性,其设计计算理论还不是很成熟。因此对于预应力混凝土管桩在地震荷载作用下的受力机理很有必要进行系统深入的研究,研究其抗震性能具有比较重要的意义。首先,针对预应力混凝土管桩的高脆性,增配不同直径的非预应力筋形成复式配筋管桩,开展足尺的现场试验。通过对《建筑地基基础设计规范》和《建筑抗震试验方法规程》关于加载制度的深入考究,确立了符合本试验的加载方案。对预应力混凝土管桩的加载过程和破坏形态进行详细的记录和分析,研究表明在水平荷载下预应力混凝土管桩的破坏形态是受弯破坏,而非剪切破坏。其次,系统研究了预应力混凝土管桩在水平往复荷载作用下的受力性状,揭示了加载过程中桩的刚度退化、耗能能力以及桩周土的累积塑性变形等规律,探讨了复式配筋管桩的破坏机制和钢筋受力机理。利用实测桩身水平位移推算了桩身变形曲率,通过变形曲率来反映桩身弯矩的分布,取得了良好的效果。研究表明:复式配筋管桩的位移延性系数较常规管桩大,表明其延性得以改善,且存在一个最优的非预应力筋配筋率,本试验结果显示非预应力筋配筋率为0.75%时管桩延性最好。管桩钢筋应力集中分布在沿桩身5.5m(11D)范围内,其余部分应力几乎为零。最后,通过往复加载与单向加载试验结果的对比,验证了往复加载制度的可行性。综合规范关于单桩水平承载力特征值的公式,提出了复式配筋管桩单桩水平极限荷载计算公式,进而得到桩身允许裂缝时单桩水平承载力特征值计算公式。更多还原

【Abstract】 As a reliable pile type of prefabricated pile,prestressed concrete pipe pile has lots of advantages,such as,high bearing capacity of a single pile,reliable quality,energy saving and environmental protection,construction speed,as well as good economic benefits and so on,widely used in the engineering construction.After the underconstruction residential building collapsed events in Shanghai Lotus,the problem of the prestressed concrete pipe pile gradually aroused attention of the domestic engineering sector.Some areas have done a corresponding restriction on the application of the prestressed concrete pipe pile in different soil layer in order to ensure the safety of prestressed concrete pipe pile under horizontal seismic load.However,design and calculation theory is not very mature,due to special engineering properties of prestressed concrete pipe pile and the complexity of aseismic mechanism of prestressed concrete pipe pile foundation.So,it is necessary to study mechanism of the prestressed concrete pipe pile under earthquake load systematically and deeply.Study of its seismic performance is of much important significance.Firstly,in view of the high brittleness of prestressed concrete pipe pile,compound reinforced concrete pipe pile is made by collocating non prestressed reinforcement additionally and full scale in-situ tests are carried out.The test loading program is made through research of the "building foundation design code" and "building seismic test method" on the loading system.The loading process and failure mode of the prestressed concrete pipe pile are recorded and analyzed in detail.Research shows that the damage form of prestressed concrete pipe pile under horizontal load is flexural failure,rather than shear failure.Secondly,loading behavior of the prestressed concrete pipe pile under horizontal cyclic load is studied systematically,revealing the law of stiffness degradation,energy dissipation capacity and the accumulation of plastic deformation of the soil around pile,discussing the failure mechanism and the loading mechanism of the reinforcement of the composite reinforced concrete pipe pile.Pile deformation curvature is calculated using the measured horizontal displacement of pile.Distribution of bending moment of pile can be reflected by deformation curvature of pile and good effect has been obtained.The study result shows that the displacement ductility coefficient of composite reinforced concrete pipe pile is larger than that of conventional pipe pile and ductility can be improved.At the same time,there is an optimal ratio of non prestressed reinforcement.The test results shows that the ductility of composite reinforced concrete pipe pile is optimal when the ratio of non prestressed reinforcement is 0.75%,that is,the optimal ratio of non prestressed reinforcement is 0.75% in this case.The reinforcement stress of the pipe pile distributes in the range of 5.5m(11D)along the pile shaft concentratedly and the rest is almost zero.Lastly,feasibility of reciprocating loading system is verified,through the comparison of the test results of the reciprocating loading and the unidirectional loading.Referring to the formula for the characteristic value of the horizontal bearing capacity of single pile in the codes,calculation formula of horizontal ultimate load of a single pile of composite reinforced concrete pipe pile is proposed,and calculation formula of the characteristic value of horizontal bearing capacity of single pile under the allowable crack of the pile is proposed.更多还原