A Research Of Tunnel Surrounding Rock’s Mechanical Parameters Based On Displacement Back Analysis

With the development of China’s market economy, west development, more and more tunnels have been built, from the coastal areas to the western mountainous areas, the number of road tunnels and the scale of construction grow rapidly. This paper takes the Dapingshan Tunnel for example, with the monitoring datas,MIDAS/GTS and BP neural network, forecast surrounding rock’s mechanical parameters. We can use the back analysis results to guide the tunnel excavation.The main work of this study includes the following aspects:(1) Collects and finishes Dapingshan tunnel excavation and support programs, have a brief analysis of the measures of the key and difficult construction;(2)Introduces the relationships of monitoring and displacement back analysis, present the role and purpose of monitoring in the tunnel construction. Introduces the monitoring and instruments layout in the typical section of the tunnel, Sorts and process the monitoring dates;(3) According to the tunnel engineering geological conditions and the orthogonal experiment, determine the range of the surrounding rock ’mechanics parameters, establishes the tunnel analysis mechanical model, calculating the corresponding displacement values, by using the MIDAS/GTS program packet;(4) Trains BP neural network with the dates of Orthogonal test and the displacement values, MIDAS/GTS simulates the tunnel excavation with the output mechanical parameters, calculate the surrounding rock’ displacement. Analysis the correctness and reliability of the output mechanical parameters, comparing with actual displacement.The research of surrounding rock’s mechanical parameters based on displacement back analysis, can estimate mechanics parameters of the research range of the rock. With the integration of the design, construction and measurement, it can better feedback and service the construction.