Characterizing Structural Bearing Capacity and Deformation Behaviors of Micropiles under Multi-Stage Static Loading
Characterizing Structural Bearing Capacity and Deformation Behaviors of Micropiles under Multi-Stage Static Loading
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DOI：
10.1007/s12205-023-0403-7
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发表时间：
2023-01
影响因子：
2.2
通讯作者：
Xueyuan Zhang;Luqiang Ding;C. Xiao;Yang Song
中科院分区：
文献类型：
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作者：
Xueyuan Zhang;Luqiang Ding;C. Xiao;Yang Song
研究了微型桩的结构承载力和变形特性，考虑了微型桩长度（L）、钢管外径（d）和壁厚（t）、注浆孔直径（r）和间距（s）以及浆液水灰比（w/c）等因素的影响。对20根微型桩进行了多级轴压试验，获得了桩周浆液开裂（Pcr）、钢管屈服（Py）和整体结构破坏（Pult）时微型桩的变形特性和轴压荷载。实验结果表明，PcrandPy分别为0.20-0.45和0.85-0.95倍Pult.一般情况下，Put随L的增大而减小。与增加t相比，增加d对Put的改善更为显著。脉动的影响与钢管的刚度和强度的削弱有关。不同w/c值的微型桩的Pult值基本相同，但Pult值下的轴向位移随w/c值的增大而增大。在相同的Lorw/c条件下，增大d，轴向位移apult明显减小。在现有的准则中，对Put和容许轴向压缩载荷Pc的预测方程的性能进行了比较和评价。在此基础上，考虑L、d、t、r、s和w/c等因素的影响，提出了几种经验模型，分别对微型桩的Put和Pc进行了预测，并取得了较好的预测效果。
This study investigates the structural bearing capacity and deformation behaviors of micropiles considering various influence factors including the length (L) of micropiles, outer diameter (d) and wall thickness (t) of steel pipes, diameter (r) and spacing (s) of grouting holes, and water cement ratio (w/c) of grout. Multi-stage axial compressive tests were performed on 20 micropiles to obtain their deformation behavior and axial compressive loads respectively corresponding to the cracking of surrounding grout (Pcr), yielding of steel pipes (Py), and global structural failure (Pult). Experimental results reveal thatPcrandPyare respectively 0.20–0.45 and 0.85–0.95 timesPult. In general,Pultdecreases withL. Increasingdproduces a more significant improvement inPultcompared to increasingt. The influences ofrandsonPultare associated with the weakening of stiffness and strength of the steel pipes. Micropiles with variousw/clevels perform similarPult, whereas their axial displacement atPultincreases withw/c. Under the sameLorw/ccondition, increasingdleads to an obvious reduction in the axial displacement atPult. In the existing criteria, the performance of prediction equations forPultand allowable axial compression load (Pc) was compared and evaluated. Furthermore, several empirical models were proposed to respectively predictPultandPcof the micropiles considering the influences ofL, d, t, r, s, andw/cand achieve well predictions.