Study On The Aging Deterioration Curve Of Tunnel Lining In Water Rich Area

Nowadays,more and more attentions have paid to environmental protection.The water control scheme of "drainage-based and drainage-blocking combination" in tunnel construction is increasingly replaced by the principle of "plugging-based and drainageblocking combination".This means the tunnels in water-rich areas may face the role of groundwater during operation.Groundwater will exert pressure on the outer surface of lining and accelerate the inferiority of surrounding rock and lining materials.In this way,the security of the structure is affected.On the basis of summarizing the main influencing factors of tunnel lining deterioration,a numerical model is established by using the method of numerical analysis to analyze the deterioration factors of single deterioration factor(i.e.,only groundwater level change,only surrounding rock deterioration and only lining material deterioration),and combined deterioration factor(i.e.,under groundwater level change,surrounding rock deterioration,lining material deterioration and surrounding rock and lining material deteriorate at the same time).The law of stability of surrounding rock,stress of secondary lining,structural safety and crack width over the years are studied and the main research results are as follows:(1)The change of the groundwater level has the most significant influence on the stress characteristics of tunnel lining and the stability of surrounding rock.The rise of groundwater level makes tunnel appear obvious phenomenon of vault sinking and invert floating.When the water level has passed the vault,the axial force and bending moment of lining structure increase significantly,which directly leads to the decrease of structural safety factor and the increase of crack width.(2)The deteriorated surrounding rock is prone to damage under the influence of groundwater,which directly shows the significant expansion of plastic zone.(3)The deterioration of lining material will not have a significant impact on the stability of surrounding rock and the stress characteristics of lining.It shows that using the method of reducing elastic modulus to simulate the deterioration of lining material will enhance the deformation ability of structure,and will not change the minimum safety factor of the structure.(4)No matter what kind of deterioration,the position of wall foot on both sides and the invert are the most disadvantageous position in tunnel section.They are under high risk of cracks and seepage,which should be paid attention during the tunnel construction,operation and maintenance.