GFRP筋土钉支护钉头的锚固性能

Anchorage performance of nail head for GFRP bar soil nail support

土钉钉头为土钉墙整体结构中的薄弱部位,为研究土钉钉头锚固性能,以一种装配式柔性面层GFRP筋土钉墙为例,通过室内钉头锚固性能试验及三维数值模拟对外径32 mm的中空GFRP筋钉头的极限抗拉强度、钉头变形及破坏规律进行研究。研究结果表明,该GFRP筋钉头极限承载力在240~290 kN之间,当螺母拧紧时螺纹副的应力主要分布在螺纹牙前3环,其中以钉头第1环螺纹牙应力集中现象尤为明显;此外,采用螺纹展开法建立钉头螺纹牙的力学模型,得出了第1环螺纹极限剪切强度与钉头极限荷载之间的关系,并通过计算得出该GFRP筋钉头极限承载力为244.54 kN,与试验结果相符。通过室内钉头锚固性能试验的脆性破坏特点,确定GFRP筋钉头安全系数在1.8~2.0之间,并判定此种GFRP筋安全荷载在125~135 kN之间。

The soil nail head is the weak point in the overall structure of the soil nail wall.In order to study the anchorage performance of soil nail head,this paper takes an assembled flexible surface GFRP reinforced soil nail wall as an example.Through indoor nail head anchorage performance test and 3D numerical simulation the ultimate tensile strength,nail head deformation and damage pattern of hollow GFRP bar nail head with 32 mm outer diameter were investigated.It was found that the ultimate load bearing capacity of such GFRP bar nail head is between 240 kN and 290 kN.When the nut is tightened,the stress of the thread is mainly distributed in the first three rings of threaded teeth,with significant stress concentration exists at the first ring of threaded teeth in the head of the nail.In addition,a mechanical model of the threaded tooth of the nail head was developed using the thread expansion method,and the relationship between the ultimate shear strength of the first ring thread and the ultimate load on the nail head was derived.The ultimate load-carrying capacity of this GFRP bar nail head was calculated to be 244.54 kN,which is consistent with the test results.The brittle damage characteristics of the indoor nail head anchorage performance test determined that the safety factor of GFRP tendon nail head is between 1.8 and 2.0.It is also determined that the safe load of such GFRP tendons is between 125 kN and 135 kN,providing a reference for the research and application of similar projects.