Study On Engineering Geological Characteristics And Surrounging Rock Deformation Of Yayu Tunnel

With the development of the national economy,China's infrastructure has been continuously promoted,and a large number of railways and highway tunnels have been continuously built.Tunnel excavation will destroy the initial state of the surrounding rock,which will cause deformation or damage and affect the tunnel construction.The soil surrounding rock section belongs to the high-risk area in the tunnel.Due to the poor surrounding rock conditions of such sections and the complicate situation,So the surrounding rock deformation and damage are easy to occur during the excavation process.Monitoring and measuring during construction,analyzing the deformation law of surrounding rock during tunnel excavation,has a significant effect to tunnel safety construction.Therefore,it is important to study the deformation of tunnel surrounding rock.This paper takes the Yayu Tunnel as the research object,briefly introduces the engineering geological conditions of the Yayu Tunnel.Based on the monitoring and measurement data of the arch settlement and surrounding convergence,the causes and characteristics of the deformation problems of the soft rock in the Yayu Tunnel are explored and adopted.and use MIDAS/GTS simulation software to simulate the tunnel and obtains the following research results:1.Based on the actual geological conditions,lithological conditions and regional geological structure of the Yayu Tunnel,analyze the engineering geological problems existing in the Yayu Tunnel.According to the geological record data,the tunnel is divided into surrounding rock grades.2.We summarize the current monitoring and measurement methods adopted by the tunnel and process the data of the on-site monitoring and measurement data.Selected reasonable function relationship to make a regression analysis of the surrounding rock deformation.Predicts the final deformation and compare the current deformation to determine stability of the surrounding rock.Obtain the displacement-time diagram and summarize the deformation law of surrounding rock.The deformation characteristics are follow:The settlement of the v-shaped surrounding rock vault and the surrounding convergence displacement are larger than that of the Class IV surrounding rock.The time required for the stability of the V-classsurrounding rock is longer than that of the IV-class surrounding rock,and the deformation of the right-section of the same section is slightly larger than that of the left-section.3.The deformation and failure modes of the Yayu tunnel are analyzed,and the deformation mechanism and main influencing factors of the Yayu tunnel are summarized.Combined with the disease situation of the tunnel,we propose reasonable management measures.4.The MIDAS/GTS model was used to establish the soil shallow buried section model,simulates the deformation of each stage of the construction of the Grade IV surrounding rock and the V-class surrounding rock in the Yayu Tunnel,clarifies the risk location during construction,and analyzes the time required for the surrounding rock to stabilize.At the same time,compare the deformation of surrounding rock in the construction stage during the excavation process of the upper and lower step method,the reserved core soil method and the single-sided guide pit method,and we think the single-sided guide pit method is best method.