Study On The Strength Calculation Theory And Standard Test Method Of Earth Block Masonry

With the increasing attention paid to the environment around the world,sustainable development has attracted great attention in the field of civil engineering,and the application of earth materials which possesses outstanding ecological benefits and universal geographical applicability in architecture has become a research hotspot.At present,most of the researches on earth materials in China is still in the experimental stage,and there is no unified test method and calculation theory for the strength of earth block masonry.Starting from masonry,this paper explores the mechanical characteristics of earth block masonry,and the test method and calculation theory for the strength of the earth block masonry was established,which promotes the development of earth materials towards standardization,routinization and construction normalization in practical engineering.The main research contents are as follows:1.Starting from the inheritance and development of traditional adobe manufacture technique in China,this paper summarized and sorted out the manufacture techniques of various earth blocks,and studied on the traditional adobe manufacture techniques in detail from the aspects of material selection,size determination,production process,maintenance and storage.Finally,the traditional method of making adobe in China is formed.The traditional adobe manufacture technique is improved combining with the modern technology of brick making.This paper makes a comprehensive comparison and analysis on the manufacturing technology of various earth blocks from the three aspects of technological advancement,economic efficiency and the quality of block,which points out the optimization direction of existing technology and provides a reference for the development of manufacture technology for new type earth block.2.A systematic study was made on the strength test method applicable to the earth block.The compressive strength of the molded adobe and rammed adobe were measured by three methods respectively,namely the cubic specimen,the stacked specimen of two half blocks and the whole block specimen.Considering the influence of factors such as the manufacture technique of the specimen,loading direction and the capping method of loading surface,the comparative analysis of the stress state,failure pattern and the compressive strength of the block under various kinds of test methods were carried out,and a strength test method of earth block is determined,which is operative,unified and the experimental results are as close to the actual values as possible.3.The masonry specimen built by molded adobe,rammed adobe,compacted earth block and extruded earth block were tested under the uniaxial compression test for the measurement of the compressive performance.Considering the influence of masonry pattern,height-tothickness ratio,capping method of the loading surface and loading method,the regularity for the influence of the above factors on the compressive properties of the earth block masonry was analyzed from the aspects of failure modes,compressive strength,elastic modulus,Poisson ratio and stress-strain curve.And from the aspects of failure modes,shear strength,deformation ability,stress-strain characteristics and working mechanism,the effect of the block type,shearing area,shearing direction and bond joint materials on the shear performance along the joint of the earth block masonry were studied,and the regularity of various influence factors as well as the typical features of the shearing stress-strain curve for the earth block masonry were obtained.The micromechanical models of various shearing specimens were established in ABAQUS software for the finite element analysis,and the regularity for the influence of factors such as block size,specimen form and the elastic modulus of block and bond material on the stress distribution on the shearing joint section was obtained.4.Based on experimental study,from the aspects of maneuverability,reproducibility,instruments and equipment requirements,the analytic hierarchy process and grey correlation analysis method were implemented for the comprehensive evaluation of the controlling parameters such as the masonry pattern,height-to-thickness ratio,capping method of loading surface and loading method in the compression test of earth block masonry as well as the specimen form and shearing direction in the shear test along joint.And the optimal parameters were selected for the determination of the standard test method for the compressive strength and shear strength of the earth block masonry.5.Statistical analysis and theoretical derivation are used to establish the calculation method of elastic modulus of earth block masonry.The proposed calculation method can directly calculate the elastic modulus through the compressive strength of masonry,and can also calculate the elastic modulus by the compressive strength of block and bond material,which possesses excellent accuracy.The characteristics of the compression stress-strain curve of different types of earth block masonry were summarized,and the stress-strain curve without progressive hardening behavior and with a progressive hardening behavior was described using the revised Zhong Jiqing model and the piecewise model.The compression constitutive model of the earth block masonry is obtained,which shows good agreement with the test curve,and can well reflect the stress-strain characteristics of various earth block masonry under compression.6.The strength calculation problem of earth block masonry was solved by artificial intelligence technology.The Artificial Neural Network(ANN)and Adaptive Network-based Fuzzy Inference System(ANFIS)were combined for the calculation of the compressive strength of the earth block masonry.Firstly,regarding the existing masonry compressive strength calculation formula,An ANN model was established with the strength of bond materials and block as input variables for the prediction of the compressive strength of earth block masonry.Then introduce the height-to-thickness ratio to correct the calculation results using ANFIS.By comparing the predicted results of the model with the calculated results of the existing masonry compression strength calculation formula,the effectiveness and applicability of the artificial intelligence technology are verified.Through the experimental study and theoretical analysis,the test procedure for the compressive strength of earth block was given,and the standard test methods for the strength of earth block masonry were established.Finally,the compression constitutive model,the elastic modulus calculation method and compressive strength calculation method of earth block masonry were proposed.All the aforementioned contributions provide important test basis and theoretical reference for the application of earth materials in practical engineering and bearing capacity design of earth block masonry structures.