新型多节泡压密注浆土钉的抗拔机理及计算方法研究

多节泡压密注浆土钉，其杆体中空，能根据需要灵活生成多个增大压密和锚固效果的节泡，较传统土钉具有显著的加固效果。由于这种新型土钉尚处于应用探索阶段，其工作机理与计算方法尚不明确。本项目拟采用模型试验和理论分析的方法，对该新型土钉在多参量影响下的抗拔机理和计算方法开展研究：（1）基于土钉参数及土层条件可控的试验系统，开展有/无压密注浆的拉拔对比试验和理论分析，揭示注浆压密效应对土钉抗拔性能的强化机制，探明其对抗拔力的影响规律；（2）开展考虑节泡直径、节泡间距、上部荷载和土体相对密实度等多参量影响的拉拔试验，探明新型土钉的破坏面演化特征、破坏模式和抗拔力演化规律；（3）结合上述多节泡压密注浆和多参量影响的试验结果，揭示该新型土钉的工作机理和破坏特征，并提出相应的抗拔力计算方法。预期成果可发展和完善该新型土钉的计算理论，为其推广应用提供试验支撑和理论基础。

The compaction-grouted soil nail, whose hollow nail rod can be manufactured and installed with multiple grout bulbs to enhance the stabilized performance in application, shows a better performance comparing with the conventional soil nail. However, as the soil nail is newly developed, the working mechanism and pullout force calculation are not clear so far. Therefore, this project will conduct studies on the pullout mechanism and calculation approach under different parameters using physical model test and theoretical analysis. The sequences of the project are: (1) series of comparative tests with/without grouting process will be carried out to clarify the increase mechanism of pullout force and quantify the contribution of the compaction grouting to the increase of pull-out force; (2) another series of pullout model tests will be carried out to investigate the propagations of failure surface, failure modes and evolutions of pullout force under different diameters and spacings of grout bulbs, overburden pressures and void ratios; (3) different analytical models which consider the influence of compaction grouting effect to calculate the pull-out force of a soil nail will be proposed based on different failure modes. The outcomes of the research project will be a necessary supplement for the development of the computing theory of the new soil nail, which then provide experimental and theoretical bases for the application in designs and constructions.