| Usually,the stability of subway tunnel structure is obviously related to the pile foundation nearby.With the increase of pile foundation load,the stress situation of subway tunnel will be changed obviously,and the tunnel structure will be changed,for example,it is easy to cause the cracking and seepage of tunnel lining,which makes the whole tunnel become complete.The operation of a subway system has been threatened.Therefore,it is necessary to study and analyze the pile foundation load,explore its impact on the tunnel and the mechanism of action,and take preventive measures.In this paper,the above-mentioned influence mechanism is studied and analyzed,and a three-dimensional model is constructed by the finite element method,and the relevant calculation program is compiled.Several factors affecting tunnel deformation are simulated and analyzed,and the prevention and treatment methods are put forward,which can provide reference and guidance for relevant practical projects.The details are as follows:(1)The load effect of pile foundation and the theory of tunnel deformation are introduced in detail,the concrete process of single pile vertical load is discussed,and the influencing factors of tunnel longitudinal deformation are summarized.It is found that:(1)pile-sinking effect is mainly affected by construction technology,which should be designed and calculated according to specific construction conditions;(2)end-bearing and friction pile groups,whose pile length,pile diameter and pile top load are stable,tunnel displacement is mainly affected by pile-tunnel spacing,so it is possible to choose to increase the pile-tunnel spacing.Method to reduce tunnel displacement.(2)Based on the comprehensive analysis of the engineering geological data of the Airport Avenue Crossing Bridge,a series of three-dimensional numerical simulation results and their analysis are carried out.It is considered that the design scheme of the Airport Avenue Crossing Bridge construction project is basically feasible,but the risk of collapse induced by the potential karst soil cave in the site may be triggered by the pile foundation construction should be paid full attention to.And to avoid affecting the safety of subway structure and subway operation safety.According to the monitoring results,it is found that the influence of rotary excavation pile construction technology on tunnel structural deformation is within controllable range.(3)Combining with the engineering geological conditions,foundation pit excavation method,pile foundation arrangement,bridge structure characteristics of the construction project of Airport Avenue Overpass Bridge,and the structural characteristics of subway shield tunnels,intermediate air shaft and connecting passages,the model is established.It is found that the force of subway structure is at a lower level,which induces the variable of subway structure stress.Smaller.At the same time,it is considered that the unfavorable influence of the construction of the overpass bridge on the subway structure is mainly reflected in the following three aspects:(1)the disturbance caused by the excavation of the foundation pit of the overpass bridge cap to the subway structure;(2)the negative influence caused by the construction of the short-distance pile foundation of the overpass bridge;(3)the negative influence of the overpass bridge load and the operation load on the subway structure,so as to ensure the subway structure Safety and safety of subway operation are proposed. |
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