复合材料抗浮锚杆的锚固机理与承载特性试验研究

With development of urban underground space, the foundation depth of buildings is increasing continuously and anti-floating problems are becoming more and more serious. Compared with other measures, anti-floating anchor has more advantages, such as strong layer adaptability, dispersing the stress, convenient for construction, lower cost and higher capacity in hard geotechnical layer. However, the metal bolt is more corrosion and the durability is worried. Especially in construction of urban rail transit such as subway, the metal bolt is forbidden because the stray current, caused by DC power system, can produce electrochemical corrosion to metal. In this situation, the non-metallic anchor become the best choice..Recently, glass fiber reinforced polymer (GFRP) is more and more used in common bolt. Nevertheless, there is almost not any report about GFRP used in anti-floating anchor. This application project would solves the durability problem of anti-floating by means of introducing the non-metal material to anti-floating anchors. A series of experiments on anti-floating anchors of GFRP including new optical fiber measurement are conducted to discover its stress distribution, failure mode, anchorage with foundation slab, behavior under long-term load and a concept of whole deformation is proposed. The analysis and design theory on anti-floating anchors of GFRP are established based on both deformation and capacity, which lay a foundation of extension on GFRP anti-floating anchors.

随着城市地下空间的开发利用，建筑物的基础埋深不断加大，抗浮问题变得越来越突出。相比其他抗浮措施，抗浮锚杆具有地层适应性强，分散应力，便于施工，节约造价等优点，在硬质岩土层中承载力大，更具优势。但金属锚杆容易锈蚀，耐久性问题令人担忧。特别是在地铁等城市轨道交通建设中，由直流供电系统产生的杂散电流，对金属产生电化学腐蚀，不容许采用金属锚杆。在这种情况下，使用非金属锚杆成为最佳选择。.近年来，玻璃纤维增强聚合物（GFRP）材料用于普通锚杆的研究增多，但国内外尚无GFRP材料用于抗浮锚杆的报道。本申请项目将GFRP材料引入抗浮锚杆，彻底解决抗浮锚杆的耐久性问题。对GFRP抗浮锚杆进行新型光纤测试等一系列试验，探索其应力分布、变形构成、破坏模式、与基础底板的锚固以及长期荷载作用下的性态，提出"全变形"的概念，建立变形和承载力双控的GFRP抗浮锚杆分析和设计理论，为GFRP抗浮锚杆的推广应用奠定基础。

玻璃纤维增强聚合物（GFRP）锚杆具有比强度高、耐腐蚀性强、介电性好等优点。GFRP抗浮锚杆能够克服传统金属锚杆存在的地下水腐蚀和电化学腐蚀等问题，特别适用于地铁车站抗浮。本项目主要工作及研究成果如下：.1、成功地将裸光纤光栅传感植入技术应用于抗浮锚杆拉拔试验中，并与钢筋抗浮锚杆进行对比。研究表明：（1）GFRP短锚杆主要发生砂浆和围岩界面（第二界面）剪切破坏，长锚杆在锚杆杆体和砂浆界面（第一界面）出现剪切破坏；（2）GFRP锚杆的应力传递深度比钢锚杆大，剪应力峰值比钢筋锚杆大；（3）GFRP抗浮锚杆的极限抗拔承载力高于钢筋抗浮锚杆。中风化花岗岩地层中，GFRP抗浮锚杆的合理锚固长度建议取值为3.5～5.0 m。.2、通过自行设计的室内大型构件对拉试验，研究了不同锚固形式和不同锚固长度的GFRP抗浮锚杆的外锚固性能。结果表明：（1）GFRP抗浮锚杆外锚固的破坏形式有锚杆材料强度不足产生劈裂破坏以及GFRP锚杆和混凝土界面相对滑移较大产生拔出破坏两种；（2）对于直锚筋锚固和螺母托盘锚固的GFRP抗浮锚杆，外锚固长度为30d 的极限承载力比外锚固长度为15d的极限承载力提高约43.8%~65.6%。螺母托盘锚固有助于提高拉拔力；（3）试验锚杆的外锚固变形量均不超过2.5 mm，能够满足工程需要。.3、通过全长黏结螺纹GFRP抗浮锚杆在长期荷载作用下的拉拔蠕变试验，研究了GFRP抗浮锚杆抗拔的蠕变力学模型。所建立的蠕变损伤模型用于预测GFRP抗浮锚杆的长期抗拔承载力具有较好的适用性。.4、在内锚固、外锚固及蠕变试验的基础上，分析论证了GFRP抗浮锚杆第一界面、第二界面及杆体材料的剪切破坏机制，并提出了“全变形”的概念，有助于深化对GFRP抗浮锚杆工作机制的认识。.5、成功地在GFRP锚杆杆体内、锚固体中和第二界面植入三重光纤光栅传感器串，通过拉拔试验测得了锚固体和第二界面的轴应力、剪应力分布以及锚杆杆体和锚固体位移上拔量，研究了GFRP锚杆的承载性能及锚固体中轴力、剪力变化规律。