Deformation And Damage Assessment Of An Existing Masonary Building Subjected To Tunneling

With the rapid development of the urban economy,the interrelations between each district of the city are getting closer.Generally,the metro constructed by the shield method is gradually becoming a main way to strengthen the regional traffic with the advantages of large traffic volume,no occupied ground space and little effect on environment.As a result,the construction of metro tunnels is usually carried out at central area of the city where the road conditions are complex and there are many im-portant buildings.The unavoidable impacts of the shield construction on the adjacent buildings,especially for masonry structure,have attracted considerable attention and the research on it has a very significant value of engineering practice.Based on the field monitoring data of the shield tunneling of Changsha Metro Line 4#orthogonal crossing a masonry structure,the remarkable change of construc-tion parameters and the effect on settlement are analysed due to the shield tunneling crossing through the soft-hard-interface rock.The deformation and damage of builiding induced by shield tunneling are analyzed by combining finite element nu-merical analysis and actual situation.The investigated contents and outcome of this study are listed as follows:(1)The harmonious relations among the construction parameters and the correc-tion between the construction parameters and geological conditions is investigated,which indicates that the soft-hard-interface rock plays an important role in ensuring the stability of the shield construction(2)The settlement of ground and upper masonry structure during the excavation of the shield tunnel are analyzed.It indicates that the settlement increased rapidly during the period of crossing of the shield tunneling,the maximum settlement reached 36.98mm and the maximum partial incline reached 2.83mm/m.The shape of the cracks of the building by the shield tunneling is identified as a Chinese letter as"? ".The level of cracking of wall in the hogging region of the transverse settlement trough is more severe than the sagging region.(3)In this paper,11 historical case of shield tunnel passed through the existing old masonry-concrete structure are summarized.The damage of existing masonry structures in the actual project case caused by shield tunnels is assessed.(4)Additional deformation and strains in the existing masonry structure arising from the shield tunneling are analyzed by 3D finite element method(Plaxis3D).The research results show that the principal tensile strain region obtained by finite element method can well reflect the wall cracking rules.