| China has great resources,the southwestern region is steep and mountains.Guizhou is located in the Yunnan-Guizhou Plateau,with various topography and geomorphology,complex geology,karst landforms and faults.With the improvement of China's national strength and the progress of scientific and technological innovation,China's highway industry has developed rapidly.By the end of 2018,China's total road mileage totaled 4,846,500 km,and roads and tunnels were 17,738.The total length of road tunnels was 17,236,100 m.This paper analyzes the construction mechanics effect of the shallow buried tunnel at the entrance of the tunnel.The construction of the tunnel entrance and exit sections is usually in the shallow buried bias section.The thickness of the tunnel cover is relatively thin,and the bias phenomenon is formed due to the slope of the ground.Understand the stress characteristics and laws of surrounding rock and tunnel support structure during excavation,and analyze it.The tunnel is constructed by the step method.The finite element software ANSYS is used to simulate the deformation law and mechanical effect of the surrounding rock and tunnel support structure during the excavation and support,and the parameters of the tunnel support structure are optimized and analyzed.,The main contents are as follows:(1)Processing and analyzing the raw data of the actual monitoring measurement,and based on the GM(1,1)gray prediction model of the fractional expansion operator,using MATLAB to calculate and analyze the model,analyze the original data,and pass the error test formula.The simulation value is compared with the actual value to analyze the change of the tunnel displacement,and the construction can be guided;(2)Based on the actual project,the three-dimensional model of excavation support finite element analysis is established by using the step method to construct the shallow buried bias tunnel portal section,and the surrounding nodes of the surrounding rock are extracted from the model to analyze the shear resistance of the surrounding rock.Safety factor.Analyze the stress and plastic zone variation of surrounding rock.(3)The force analysis of the bolt,the supporting structure and the pipe shed is carried out,and the influence of the tunnel bias is judged from the state of the anchor and the supporting structure,and the horizontal displacement of the pipe shed can be used to judge the biasing effect.Impact.(4)By changing the thickness of the shotcrete and the geometric section size of the steel arch,a number of experimental model schemes are established,and the effect of the support structure on the deformation control of the surrounding rock is analyzed and analyzed,which can provide a corresponding basis for the construction. |
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