Study On The Calculation Of Shotcrete And Rock Bolt Support Lattice Beam And Analysis On Three-dimensional Finite Element

The development of deep foundation pit support technology has been promoted by the process of urbanization, with a variety of methods having emerged at the same time. The technology of lattice beam shotcrete and rock bolt support has been being widely used, because of its advantages, such as convenience of construction, taking small space and economy and security. At present, there are a lot of researches about this timber form at home and abroad, in which many the studies rely in the anchor or anchor of pre-stressed, both in the theoretical aspects and the test ones, while the research about lattice beam is little. Theoretical system, not only in qualitative or quantitative, has not formed. Lattice beam is a very important part of the beam shotcrete and rock bolt support system. It has direct relationship with the quality of the whole support system's working conditions. The mechanical character of lattice beam is complicated, influenced by the factors of Ground conditions, anchor action and so on. Designers usually design lattice beam according to structural design requirements and experience, calculating with the structure of the simple beam and continuous beam. However, these methods are not entirely suitable for lattice beams, with obviously unreasonable aspects. Therefore, the research on lattice beam is very necessary and urgent.This paper introduces double set parameter method and Modified Winkler foundation model method with horizontal force being taken into account, both of which are based on the winkler common method that considers the interactions of beam and foundation, then deduces calculation formula of three-parameter method to calculate lattice beam. Programming with mathematical software Matlab, this paper calculates and analysis the changeable discipline of foundation and beam stiffness, and analysis the applicability of several improved lattice beam calculation methods. Through comparing the measured values with the original winkler methods and improved Winkler, which the foundation model with horizontal force has been taken into account, verified the advanced nature of improved method. Lattice beam is being monitored in the deep foundation pit of Qingdao coastal Garden. After longitudinal beam having been chosen as the study object, the internal force has been counted, through measuring the strain of the beam. The strained condition of lattice beams in the project has been simulated by the structural analysis software of ANSYS. The interaction between beam and soil has been truly simulated and the space function of beam has been also visually reflected. In this paper, the model received a reasonable simplification and boundary treatment, having simulated excavation in the course of seven different beam conditions. The feasibility of this method is verified, as the results through calculating and measuring having minimum differences.By means of the study on lattice beam shotcrete and rock bolt support, this paper has proposed the design and calculative methods for Qingdao region, and has given some suggestions for other types of ground conditions. The design and calculation on the lattice beam shotcrete is moderately valuable, especially the software of ANSYS having been applied.