Experimental Study On Shear Resistance Of ECC-Tibetan Rough Stone Masonry Bonding Interface

At present,the state vigorously promotes the rural revitalization strategy and the construction of characteristic villages and towns,advocates the organic combination of rural residential architecture and the inheritance of national culture,and Tibetan traditional rubble stone architecture is a precious wealth in our construction industry and construction culture.It is of great significance to protect and maintain Tibetan traditional rubble stone architecture.As rubble buildings are usually made of rubble,yellow mud and other geo-materials,the building’s resistance to external load is limited,and the frequent earthquakes in Tibetan areas,cold and exposure to the sun and other factors,resulting in settlement,tilt,cracking,collapse and other damages of different degrees after normal use for a period of time.The special and unique construction process of the building substrate makes it a difficult problem in the maintenance and reinforcement of this kind of building.How to improve the mechanical properties of the Tibetan rubble building has become an urgent matter in the engineering field.Therefore,in this paper,the high performance ECC cementing material,which is widely used in the engineering field,is used to strengthen the Tibetan rubble masonry,and the reliable interface bonding between the ECC reinforcement layer and rubble masonry is the key to ensure the reinforcement effect.Based on this,this paper adopts the method of combining experimental research and theoretical analysis to carry out research on the bonding performance of the interface between ECC and Tibetan rubble masonry.(1)Study on the preparation and basic mechanical properties of ECC cementitious materials for Tibetan-style rubble masonry reinforcement.Firstly,the ECC mix ratio at home and abroad was investigated,and seven kinds of high strength,high toughness and good micro-crack self-healing mix ratios were selected for the preparation of cementing materials.The prepared cementing materials were made into standard tensile and compression specimens.After curing,ECC basic mechanical property parameters of tensile and compression and displacements-load relationship curves were obtained.Based on the analysis of the key parameters of basic mechanics,fracture energy,equivalent toughness index and ductility coefficient,four kinds of ECC cementitious materials with high performance are selected to be used in strengthening Tibetan rubble masonry.(2)Experimental study on interface shear resistance of ECC-Tibetan rubble masonry.By analyzing the concave-convex degree of the inner elevation of Tibetan masonry,the apparent concave-convex degree of masonry is characterized by the unevenness JRC value.Four kinds of ECC cementing material reinforcement layers were respectively tested by interfacial shear tests with Tibetan masonry.The interfacial shear properties of ECC and Tibetan masonry were tested by using the strength of ECC cementing material and the apparent roughness of masonry as variables.Based on regular rubble masonry,the reinforcement effect after ECC reinforcement of general rubble masonry is analyzed.The initiation and development of cracks at the interface between rubble masonry and ECC in the process of interfacial shear test,the deformation characteristics of masonry after reinforcement and the final failure mode are obtained.The regression analysis method is used to obtain the relationship between different ECC strengths and apparent unevenness of masonry and shear properties,which is convenient to directly obtain the strength and deformation of reinforced hidden masonry based on ECC strength and apparent unevenness(JRC value).(3)Combined with the experimental phenomenon,failure mode and shear performance,the shear slip mechanism was analyzed,and the shear strength formula of different variables and shear-slip constitutive model were established.Through the quantitative analysis of the shear performance of the interface between ECC and rubble masonry with each variable,the theoretical prediction model and the test results were co MPared and analyzed to demonstrate the validity of the prediction model.