大尺寸条石无浆砌缝力学性能试验

开展10个花岗岩无浆叠砌双剪试件的低周反复加载试验,试验主要参数包括竖向压应力和石材界面处理工艺.根据试验结果分析砌缝的界面损伤特征、滞回性能、耗能能力及抗剪强度.试验结果表明:砌缝受力经历弹性、界面磨损和滑移摩擦3个阶段;试件滞回曲线形状呈饱满矩形,表现出良好的变形性能及耗能能力;随着竖向压应力水平的提高,砌缝滞回耗能总量增加;受限于加工技术精度,机切与抛光界面表现为局部不平整接触,导致往复荷载作用下界面发生类“犁沟效应”,界面动摩擦力因类“犁沟效应”有所增大;机切面、抛光面和荔枝面试件的平均动摩擦系数分别为0.84,0.82,0.75.最后,提出无浆砌缝抗剪强度计算公式,可为无浆砌石墙的设计和研究提供参考.

Test on Mechanical Properties of Large-Size Dry Stone Masonry Joint

Cyclic loading tests were carried out on ten granite dry masonry specimens with double joints. The main testing parameters were compressive stress and the treatment of the stone interface. The experimental results were discussed in terms of damage patterns, hysteretic behavior, energy dissipation capacity and shear strength of the joints. The shear behavior of the joint is characterized by three stages: elastic stage, interface wear stage and sliding stage. The hysteretic response of the specimens is approximately rectangular in shape, highlighting that the dry joint possess large deformation and energy dissipation capacity. The energy dissipation capacity of the joints improves with increase of compressive stress. Due to the limitation in the surface treatment, ploughing effect is observed in the machine-sawing and polished interfaces. Ploughing effect increases the frictional resistance of the interface. The average friction coefficients of machine-sawing, polished and buff-hammered interface joints are about 0.84, 0.82 and 0.75, respectively. Finally, an empirical expression to estimate the shear strength of dry masonry joints is proposed and compared with the experimental results, as a reference for the design of stone walls with dry masonry joints.