| With the rapid development of urbanization,making the use of urban space on the increasingly tense,forcing the development and utilization of urban underground space,excavation of the foundation pit is deeper,which is more and more important to the retaining system of the foundation pit.While as a new retaining structure,double-row pile gets a large bending and anti-lateral stiffness,which can effectively restrict the foundation and slope deformation,Especially when the application of pile-anchor support is limited,they are widely used in deep excavations in recent years.The current theoretical research lags behind practice,there is no mature design theory and calculation method.Based on the previous research results,the paper is more further research study on the retaining mechanism and calculation method,the main research work and achievements are as follows:(1)In this paper,based on the understanding of the characteristics and research status of the double-row pile retaining structure,through the analysis of the foundation pit support calculation method,the improved calculation model is put forward.According to the elastic foundation beam method,then,the differential deflection of each section can be established,according to the boundary conditions,the displacement of the double-row pile and the bending moment of the pile can be achieved,which can provide some useful reference value for the design and calculation of double-row pile retaining structure.(2)The design parameters such as row distance,pile spacing,pile top connection method,embedment of front and rear pile and surrounding pile soil reinforcement are simulated and analyzed by using FLAC3 D software,the variation law of pile moment and displacement is studied according to pile depth;The results show: 1)Reasonable spacing and pile spacing can effectively reduce the deformation of pile body,play to the role of front and rear row pile coordination and soil arching effect;2)The depth of the front pile is increased,which can obviously control the deformation of the pile body;3)The soil at the bottom of the pile is different,the effect of surrounding pile soil reinforcement is different.The soil at the bottom of the pile is weak,with the surrounding pile soil reinforcement below the bottom of the pits,the deformation constraints of the pile is more obvious.(3)The numerical analysis of the double-row pile retaining structure is carried out by using FLAC3 D finite element software in Hangzhou,and compared with the results of the improved method and the monitoring results.The distribution rules of the three results are basically the same,proving the calculation method of double-piles of this thesis is feasible and thus has a reference value for practical engineering. |
