自平衡测试技术在瀛州大桥桩基中的应用研究.pdfVIP

自平衡测试技术在瀛州大桥桩基中的应用研究 班笑，穆保岗，闫威园，景旭成，龚维明 （东南大学土木工程学院，南京 210096） 摘要：采用自平衡试桩方法研究了洛阳瀛州大桥桩基的受力性能。研究表明三根桩的极限 承载力分别为 17000kN,27000kN和 31580kN。桩的弹性压缩量在加载初期比较小，在加载后 期明显增大。较小的桩土相对位移就可以产生桩侧摩阻力,当桩土相对位移在 14-20 mm 范围 内，桩侧摩阻力发挥完全。和传统的静载试验比较，自平衡测试技术能够提高桩端摩阻力 的发挥。 关键字：自平衡测试方法；粘土岩；荷载位移曲线；压缩量；摩阻力 Pile Performances of Yingzhou Bridge by Self-balanced Testing Method Ban Xiao ，Mu Baogang ，Yan Weiyuan ，Jing Xucheng ，Gong Weiming (College of Civil Engineering, Southeast University, Nanjing 210096, China) Abstract : Self-balanced testing method was performed to investigate the load test performances of piles of Yingzhou Bridge in Luoyang City. The test results indicated that the ultimate capacities of the three piles were 17000kN, 27000kN, and 31580kN, respectively. The elastic compressions of piles were small at the initial load level, but increased obviously at the later load lever. It was clear that the skin resistance was mobilized at very small relative movement. The pile-soil relative displacement for ultimate skin friction was about 14-20 mm for clays. The end bearings of piles were enhanced by the self-balanced testing method compared with the traditional elastic method. Keyword: Self-balanced testing method; Clay rock; Load-settlement curves; Compression; Pile resistance 1 引言 瀛州大桥位于河南省洛阳市，跨越洛河，总长1543米。主桥主跨为下承式细杆拱桥，主 桥边跨为连续砼箱梁。瀛洲大桥的建设，对洛阳新区开发建设和对跨洛河南北交通的进一步 改善具有重要意义。 根据国家规范和有关规定，对该工程钻孔灌注试桩采用了自平衡法进行静载荷试验。自 作者简介: 班笑: Tel: +86 25 Fax: +86 25 Email: michelleban@ 第 531 页 平衡测试法是利用试桩自身反力平衡的原理,在桩端附近或桩身截面处预先埋设单层(或多 层)荷载箱。加载时荷载箱以下将产生端阻和侧阻以抵抗向下的位移,同时荷载箱以上将产生 向下的侧阻以抵抗向上的位移。上下桩段反力大小相等,方向相反,从而达到试桩自身反力平 衡加载的目的。该技术曾先后在润扬长江大桥、东海大桥和苏通长江大桥中成功地运用，对 于克服大吨位加载困难、传统试桩条件不具备等方面具有一定优势。 2 试验概况 瀛州大桥桥址处主要为粘土岩地基，由于时代较新，成岩程度较低