玻璃纤维锚杆在基坑支护中的应力分布规律

为深入研究玻璃纤维锚杆(GFRP锚杆)代替传统钢筋锚杆作为支护结构应用于基坑工程的可行性,本文通过现场拉拔试验探究了GFRP锚杆应力沿杆体的分布规律,通过有限元分析研究了不同参数的影响规律,并为提高GFRP锚杆在基坑工程应用的可行性,进一步探讨了常见锚具失效的机理,开发设计了新型锚杆锚具。结果表明：GFRP锚杆在拉拔过程中,轴力沿锚杆杆体呈指数型衰减,最后趋近于零,存在一个临界锚固深度,大部分轴力作用范围为0~4m左右；剪应力分布具有峰值点,大致位于离端口0.5m处,最大剪应力峰值为2.27MPa,剪应力发挥的主要区间在0.5m~3.5m范围内；轴力分布范围扩大的速率远小于拉拔荷载增加的速率,当荷载增加到极限荷载的50%时,应力分布范围趋近于最大传递距离；上覆压力变化对锚杆轴力传递范围没有明显影响；当粘聚力和内摩擦角增加到一定值时,对锚杆轴力影响开始下降；新型GFRP锚具能有助于GFRP锚杆发挥出其强抗拉特性,具有良好的工程应用价值。

Stress Distribution of Glass Fiber Reinforced Polymer Bolt in the Retaining and Protection of Foundation Excavation

In order to investigate the practicability of Glass Fiber Reinforced Polymer (GFRP) bolt instead of traditional steel bolt during a field foundation pit engineering application as supporting structure. A field pullout test is conducted to examine the stress distribution along the GFRP rebar. In addition, the finite element tests are carried out to investigate various factors. In order to improve the feasibility of GFRP bolt in foundation pit engineering, the failure mechanism of common anchorage device was discussed, and a new type of anchorage was designed. The results show that the axial forces along the GFRP bar exhibit the exponent distribution during the pullout process. A critical anchored depth can be determined which in the ranges from 0 to 4m. The shear stress distribution has a peak point, approximately 0.5m from the port, and the maximum shear stress peak is 2.27MPa. The main range of shear stress is 0.5m to 3.5m. During the pullout process, the increasing ratio of axial force distribution is quite fast than that of increasing force. When the pullout force reaches 50% of the maximum value, the shear stress distribution area is quite close to the maximum area. The overburden pressure has no obvious influence on the axial force transmission range of the bolt. When the cohesion and the angle of internal friction increase to a certain value, the influence on the axial force of the bolt begins to decrease. The new type of GFRP anchorage can help the GFRP bolt to develop its strong tensile properties and has good engineering application value.