Study On Numerical Simulation The Deformation Law Of The Deep Road Base Of The Red-bed Soft Rock Formation Of A High-speed Railway

In recent years,China’s high-speed railway has been rapid development,has become one of China’s "national business card" abroad,but also a lot of more complex new engineering problems.The standard of high-speed railway construction is higher than that of ordinary railway,and the heave deformation of the high-speed railway foundation built in soft rock area exceeds the limit of the railway roadbed design specification,which will seriously affect the high-speed and safe operation of the train and endanger the safety of the roadbed structure.At present,there are few studies on the causes,processes and mechanisms of the upper arch deformation caused by the soft rock foundation of the deep excavation,and there is no effective control measure severing of the heave deformation disease on the foundation of the soft rock formation.Therefore,the problem of continuous heave deformation of the roadbed needs to be studied,and has some engineering application value.Based on the actual project of heave deformation on the base of a deep road in the red layer soft rock formation of the red layer in southwest China,collecting engineering geological and hydrogeological survey data on the area of heave deformation disease on the roadbed,using a combination of theoretical analysis,numerical simulation and on-site monitoring,try to analyze the mechanism and law of heave deformation on the substrate continuously after the construction of the high slope of the excavation from the perspective of the creep characteristics of soft rock.On the basis of this study,the effective control measures of heave deformation on soft rock foundation are proposed,a numerical model of foundation reinforcement is established,and the control effect is compared and analyzed.The main research content and conclusions are as follows:(1)According to the drilling data of the arch edgy lot on the roadbed,the test of indoor expansion characteristics and the monitoring of arch deformation data on the section,analysis of the engineering characteristics,geological conditions and deformation characteristics of arch deformation sections on the roadbed,it is concluded that the heave deformation on the base surface of the soft rock road where there is related to the slope excavation effect and the creep characteristics of soft rock.The rock body of the base is creeped and deformed over time,resulting in long-term continuous upper arch deformation on the base of the road base.(2)Based on the theory of catapult,FLAC3 D is used to establish a numerical model of slope and to simulate and calculate the process of full excavation construction.This paper analyzes the stress,displacement field change characteristics and the variation law under the roadbed during excavation,and evaluates the stability of the slope after excavation.It is concluded that during the excavation of the slope,the deformation of the slope body is mainly vertical rebound deformation,the vertical deformation of the bottom of the excavated slope body increases linearly with the number of excavations of the earth body,but also will be affected by the excavation of the adjacent slope body,which has less effect.The vertical deformation of the substrate increases with the decrease of the vertical stress of the substrate,the greater the stress change,and the greater the vertical displacement changes with it.(3)The viscoelastic-plastic calculation is carried out on the slope model after excavation.Simulating the process of stress and displacement field changes in the slope model during the 10 years of creep,It is concluded that the change of the total displacement of the substrate is greatly influenced by the horizontal deformation,and the bottom deformation changes from the vertical to the unloaded rebound deformation to the creep deformation that points to the right side of the face.Compared with the displacement characteristics of catapult,the deformation of the slope has changed significantly in the whole rock body,and is no longer limited to the shallow surface around the excavation surface.(4)Considering the aging deformation properties of the rock,the vertical deformation and horizontal deformation of the base of the slope are the cumulative process of nonlinear changes related to time,continuous heave deformation occurs with the increase of the base surface of the road base over time;Stress in rock bodies also changes nonlinearly over time,and horizontal stress and shear stress change significantly over time.With the increase of substrate depth,the increase of horizontal stress and shear stress in rock body gradually becomes larger.(5)In the elastoplastic model,the horizontal stress of the rock mass under the basement is less than the vertical stress at the same point,the horizontal displacement change is less affected by excavation and unloading;In the viscoelastic-plastic model,after a period of adjustment of stress and strain,the horizontal stress of the rock mass under the basement is greater than the vertical stress at the same point,the horizontal deformation changes significantly with time.(6)Based on the deformation characteristics of the arch on the base of the subgrade,propose effective control measures for arch deformation on soft rock foundation,comparative analysis of its control effect.It is concluded that after the foundation is reinforced,the vertical deformation at the shallow surface monitoring point of the foundation is reduced by 44.6%,and the horizontal deformation is reduced by 18.7%.The Stress in rock body adjusted to improve its stability,this measure can better limit the creep deformation of the shallow surface of the foundation.