The Research On Seismic Reinforcement Method Drilling Reinforcement For Existing Masonry Structure Wall

Masonry structure occupies a large proportion of old houses in China,with the increase of the service life of the structure and the continuous improvement of seismic fortification standards,a large number of old masonry houses urgently need to be seismically reinforced.The "Technical Regulations for Seismic Reinforcement of Buildings" proposes reinforcement technologies such as ring beam structural columns and steel tie rods,shotcrete slab walls,reinforced mesh mortar surface layers for multi-storey masonry houses,which improves the seismic performance of existing masonry structures and withstands the test of earthquakes.Due to the reform of the housing system,the privatization of property rights and the implementation of the Property Law,the reinforcement of old houses in the new period has been difficult due to the lack of cooperation of residents.In order to promote the smooth implementation of the seismic reinforcement project of the old residential area and reduce the impact on the households,in recent years,a new type of long-distance high-precision horizontal drilling and grouting construction technology in the masonry wall has been successfully developed,which makes it possible to strengthen the old masonry dwellings without entering the house.Based on the long-distance drilling and grouting process,the influence of longitudinal drilling in the wall of existing masonry structure and the seismic reinforcement method of reinforcement are experimentally studied.The main research contents and conclusions of this paper are as follows:(1)The influence of horizontal drilling on the vertical bearing capacity of the wall was studied.Six comparison specimens,6 drilled specimens and 6 drilled specimens with casing were designed and fabricated,and the vertical axial compression test was carried out.The results showed that the cracking load of the three types of specimens is basically the same,and the ultimate bearing capacity of the specimens decreases after drilling.Drilled specimens with casing restore the compressive load capacity of the original masonry.Based on the test results,ABAQUS software was used to establish a separate finite element model of the specimen,and it was found through numerical analysis that the drilling specimen had a large degree of damage at the hole under axial compression,and the drilled specimen with sheath had stress concentration near the hole,but the damage degree was small.The numerical simulation results are in line with the experimental phenomenon,which verifies the rationality of the model,and shows that the cross-sectional bearing capacity loss caused by drilling can be compensated for by the cement slurry retaining wall and casing process,and the vertical bearing safety of the structure during construction can be guaranteed.(2)The experimental study on the influence of horizontal drilling reinforcement on the shear bearing capacity of the wall was carried out.Two reinforced wall specimens and two comparison wall specimens with different mortar strengths were designed and fabricated for low-cycle trial and error tests.The test results show that the reinforcement measure can improve the shear bearing capacity of the wall.(3)Based on the results of quasi-static test results of masonry wall,the ABAQUS finite element model is established for analysis,and the rationality of the model is verified.The parameter analysis mainly took the two wall height to width ratios and two reinforcement spacing as the research variables,analyzed their influence on the shear bearing capacity of the wall,and then compared the finite element calculation results with the relevant calculation regulations of the current masonry specification,and found that the degree of agreement was good,and the parameter analysis research results provided a reference for the research and promotion of the reinforcement technology design method.(4)Combined with the results of test and finite element simulation analysis,suggestions for improvement are put forward for the subsequent specific implementation of the construction process.According to the stress mechanism of the rear anchor reinforcement of the masonry wall,it is recommended that the calculation of the shear bearing capacity of the reinforced brick wall after the anchor reinforcement can be calculated in accordance with the relevant provisions of the current masonry specification for horizontal reinforcement,and structural columns are added at both ends of the wall to better constrain the wall and improve the seismic bearing capacity.