土遗址楠竹锚固界面传力过程研究

竹木锚固技术近年来被广泛应用于土遗址文物加固保护中,但其锚固界面传力机理尚不明确,严重制约着锚固技术的科学化、规模化应用.相关研究成果已经证实了合理的锚固界面粘结-滑移模型对锚固系统性能预测的重要性,本文在此基础上以楠竹-改性泥浆-夯土锚固系统为例,基于考虑完全脱粘现象的三线型粘结-滑移模型开展了锚固界面传力全过程研究.首先将锚固界面传力全过程分为6个连续阶段,分别对各阶段对应的界面应力、应变分布与演化过程进行理论解析,推导了锚杆轴向变形、界面滑移量、界面剪应力、界面剪应变等参数的封闭解,同时给出了极限锚固力与有效锚固长度的计算方法.在此基础上,通过识别载荷-位移曲线特征点对粘结-滑移模型参数进行了标定.最后采用两个土遗址原位拉拔试验对理论解析模型的合理性进行了对比验证,同时着重分析了锚固长度与锚杆轴向刚度两个因素对锚固性能的影响规律.本文提出的解析模型对存在完全脱粘现象的锚固界面传力过程分析具有广泛适用性,能够为土遗址锚固工程设计提供参考与指导. 

STUDY ON THE FORCE TRANSFER PROCESS OF THE ANCHORAGE INTERFACE OF BAMBOO BOLT IN THE RAMMED EARTH SITES

Bamboo and wood anchoring technique has been widely used in the reinforcement of rammed earth sites in recent years. However, its force transfer mechanism at the anchorage interface is still unclear, which seriously restricts the large-scale application of anchorage technology in scientific way. Relevant research results have confirmed the importance of a reasonable bond-slip model for predicting the performance of the anchorage system. Based on this, the bamboo-modified slurry-rammed earth anchoring system is taken as an example to study the whole process of force transfer in anchorage interface based on tri-linear bond-slip model considering complete debonding phenomenon. Firstly, the force transfer process of the anchorage interface was divided into six successive stages, and the corresponding interface stress, strain distribution and evolution process are analyzed theoretically, the closed form solutions of bolt axial deformation, anchorage interface slip, shear stress and shear strain were also derived. Meanwhile, the calculation method of ultimate anchorage force and effective anchorage length has been proposed. On this basis, the feature points parameters of bond-slip model were calibrated by identifying the different stages of load-displacement curve. Finally, the rationality of the analytical model was validated against two in-situ pull-out tests in rammed earth sites. The influence of anchorage length and axial stiffness of anchor bolt on the anchoring performance was emphatically analyzed in the text. The analytical model proposed by this paper has wide applicability to the analysis of the force transfer process of anchorage interface with complete debonding phenomenon, and can provide reference and guidance for the design of anchoring engineering of rammed earth sites.