Research On The Influence Of Shield Excavation On Existing Building Foundation

With the construction of urban underground traffic rail systems,the impact of shield excavation on adjacent buildings is also difficult to ignore.In this paper,in order to study the influence of tunnel excavation on existing pile foundations of adjacent buildings under different working conditions,the laboratory model test and numerical simulation are used to analyze the pile top under different relative positions of the tunnel and pile foundation and different lengths of the pile body.The vertical displacement and the stress condition of the pile body are studied in combination with engineering examples of different situations.Mainly carried out the following work content:(1)Carry out an indoor model test through a self-made stratum loss control model to study the impact on the surrounding building pile foundation in the case of stratum loss due to shield excavation,and use the model test with the calculated value of empirical formula obtained by previous scholars Through comparative analysis,the results show that this method can be used to more reliably simulate the formation loss caused by tunnel excavation,which proves the feasibility of this test method and the reliability of the test data.(2)Using the combined research method of indoor model test and numerical simulation to study the influence of stratum loss on adjacent pile foundations under different pile lengths and different distances between piles and tunnels.The test phenomenon shows the variation rule of the vertical displacement of the pile top under different pile distances,and analyzes the influence of the additional bending moment and the axial force of the pile body under different working conditions when the length of the pile body is different.(3)The numerical simulation method is combined with the engineering example to analyze and study the two working conditions of the shield side-penetrating building pile foundation and the shield under-penetrating building pile foundation.The theories studied in this paper have practical guiding significance for practical engineering,and use the pile displacement data and pile internal force data in the numerical simulation software to analyze,improve and enrich the study of the impact of formation loss on the adjacent pile foundation.