聚合物纤维网面层加固土坯砌体的黏结机理与抗震性能研究

Adobe masonry building, which is one of the most important forms of ancient earthen ruins and houses in small towns and villages of China, caused widespread attentions because of poor seismic behaviours in Wenchuan earthquake. This project will develop a structural system composited by polymer fiber mesh and adobe masonry. The seismic performance of adobe masonry will be improved by the high tensile polymer fiber mesh laid upon the surface of adobe masonry. The main research contents include: (1) based on monotonous and cyclic pull-out tests, the bonding stress and bonding failures between adobe masonry and mesh will be investigated, the bonding mechanism and bonding degradations will be revealed, and the key parameters influencing on the co-working of adobe masonry and mesh in earthquakes will be proposed. (2) In compared with unreinforced adobe masonry, the influences of tensile properties and arrangement of mesh and the strength of reinforcing soil surface on seismic performance of adobe masonry will be investigated; load transferring mechanism of mesh in different failure modes will be studied; the effective stress distribution law and reinforcement ratio of mesh will be proposed. (3) According to the effective stress distribution of mesh, the retrofitting methods of adobe masonry with degradation of local seismic performance will be investigated. (4) The composite mechanical model of polymer fiber mesh and adobe masonry will be proposed and used to analyze the whole process of reinforced adobe masonry in earthquakes. The research of this project will set a guideline for the following studies on the structural safety of adobe masonry buildings in the seismic zone, and will be helpful to the practice of adobe masonry.

土坯砌体建筑作为我国古建筑遗迹和村镇住宅的重要形式之一，力学性能薄弱，震害显著，汶川地震以来引起国内广泛关注。本项目拟建立一种聚合物纤维网和土坯砌体组合的结构体系，将纤维网布置于土坯砌体面层中，利用纤维网高强度抗拉性能改善土坯砌体的抗震性能。研究包括：（1）基于单调和反复拉拔试验，研究纤维网与土坯砌体黏结界面的应力状态和破坏形态，揭示其黏结性能及退化机理，建立满足二者地震中协同工作的关键参数；（2）对比未加固土坯砌体，试验研究纤维网拉伸性能、布置形式、面层强度等对改善土坯砌体抗震性能的影响，并研究不同地震破坏模式下纤维网的传力机理，建立纤维网有效应力分布规律，确定合理配筋率；（3）基于纤维网有效应力分布，研究局部抗震性能不足的已损土坯砌体构件加固方法；（4）建立纤维网与土坯砌体组合的力学模型，分析加固砌体地震破坏全过程。本项目将对提高震区土坯砌体建筑的结构安全性研究和工程实践提供依据。

土坯砌体建筑是我国古建筑遗迹和村镇住宅的主要形式之一，其抗震加固技术十分重要。本项目研究了聚合物纤维网面层加固土坯砌体的组合体系，通过化学加固土坯基体力学和耐久性、纤维网与土坯砌体间的黏结性能和机理、纤维网加固土坯砌体的基本力学性能、纤维网加固土坯墙体的抗震性能四个方面研究，表明该加固方法能显著提高土坯砌体的抗震性能。.通过适用性试验，以及直剪、抗压和劈拉力学试验，发现水性聚氨酯（PU）、正硅酸乙酯（TEOS）和硅酸钾（PS）加固土坯基体的力学和耐久性能得到显著提高，但加固剂种类及浓度与不同黏土矿物成分、颗粒级配影响下的土坯基体间应用效果存在一定差异。.通过拉拔试验，研究了土坯基体与纤维网—环氧树脂面层（FRP mesh），纤维网—环氧树脂—改性土面层（FRPSM）、聚合物纤维网—改性土面层（FRSM）加固方式的黏结性能及退化机理。FRP mesh和FRPSM加固方式，主要发生与基底粘连的剥离破坏，黏结长度超过100mm后，极限强度趋于稳定。FRSM加固方式发生加固面层整体剥离破坏。PS加固与未加固土坯基体对黏结强度影响不大。采用考虑剥离阶段摩擦和机械咬合作用的三线性模型，推导了不同阶段下的纤维材料黏结应力以及荷载、滑移表达式。.研究了FRP mesh、FRPSM和FRSM面层加固方式下土坯砌体的抗压和抗剪性能，分析了荷载位移曲线、极限承载力变化规律、峰值与极限应变变化规律、面层加固效果及失效模式。发现 FRP mesh和FRPSM加固体系中的纤维网能有效约束土坯砌体的变形，显著提高加固砌体的承载力和变形能力，但FRPSM加固体系中的改性土面层黏结界面在受力过程中出现剥离破坏，加固效果劣于其他加固体系。.研究了FRPSM和FRSM加固土坯墙体的抗震性能试验，分析了荷载位移滞回曲线、极限承载力、刚度、耗能和延性变化规律、面层加固效果及失效模式。结果表明，在大尺寸墙体试验中，FRPSM和FRSM加固体系均能有效提高墙体的抗震性能，FRPSM提高的效果更为显著，提出了FRPSM和FRSM加固土坯砌体墙抗剪强度计算模型。