Study On The Applicability Of Strata Displacement Models In Shallow-buried Tunnel Engineering

With the accelerating pace of modernization, tunnels become more common and more important in the construction of infrastructures, such as the underground pipelines and the subway tunnels. Many problems also emerged in the process of tunnel excavaton, including ground settlement, utility lines break and buildings crack and so on. In order to solve those problems, recognizing the rule of the soil displacement caused by tunnel excavation is very necessary.There are abundant of research achievements about the influence on the surrouding rock and soil mass due to the tunnel excavation. But exact analytic solution is only suitable for deep-buried tunnel, but there is still no analytic solution for shallow-buried tunnel to reveal its displacement regularity. Hence studying on this from other points of view is necessary.Based on plenty of references and engineering data, this paper consults and makes contrust between the most common models for describing the rule of the ground settlement:Peck formula and stochastic medium theory, and on this basis the model of soil deformation due to shallow tunnel’s excavation has been studied, and the engineering applicability of the displacement models has also been analyzed. As a whole, this paper concretely did the following work:(1)This paper introduced the principle of Peck formula and stochastic medium theory and the method to analyse or calculate of them. Contrasts are made between the two from from different angles. And the distinction and connection between the two are discussed. According to the definition of major influence angle, formulas of the influence radius related to common sections are proposed. And also a contrast is made between proposed formulas and the previous ones combined with some relevant engmeermg cases.(2)This paper also introduced Mair formula which described the strata settlement as well as its shortage. The main types of modifier of Mair formula are also summarized. And according to the thoery of plane strain as well as the assumption of the incompressibility of soil, the horizontal displacement formula of the soil is derived. The test data from relevant papers is used to prove the engineering applicability of derived formula. Besides, a contrast is made between the ground horizontal displacement formula of stochastic medium theory and the derived formula when it’s describing the ground situation. The result shows the similarity of the two and hence correctness of the derived formula is proved from another aspect.(3) A simple analysis of the deformetion characteristics of the shallow tunnel’s section is introduced. In order to fully simulate this effect, uniform convergence is applicated in the simulation instead to approximate the situation. Data obtained from the simulation is fitted by the displacement models, and the results prove the correctness of all these rules of soil displacement due to tunnel excavation. Last, some shortages of this subject is raised, and prospects are presented about the development and research direction of this subject in the future.