Rheological Properties Of Swelling Mudstone In Deep-buried Tunnel And Long-term Stability Analysis

At present,with the rapid development of China’s economy,my country has invested a lot of funds in the field of transportation construction in the western region in order to achieve balanced development of various regions.In the construction project in the western region,various complex geology that are difficult to predict may appear.Among them,the swelling and rheological properties of mudstone have brought many problems to the project.For this reason,to ensure that the engineering problems caused by swelling mudstone can be minimized or even avoided,and the in-depth study of the mechanical properties of swelling mudstone is of great significance to us.Based on the Xinjiang ABH Water Conveyance Tunnel Project,this paper aims at the swelling characteristics,rheological characteristics of mudstone and its influence on the long-term stability of the tunnel,and deeply investigates the mudstone section near the branch tunnel construction area of Nileke Water Conveyance Tunnel in Xinjiang.The characteristics of the surrounding rock along the line and the groundwater conditions in the area near the tunnel.According to the existing theory and experiment,the basic physical and mechanical parameters and rheological parameters of mudstone are obtained.According to the problem of initial support deformation during the actual construction process on site,FLAC3 D numerical simulation software is used for calculation to simulate the force and deformation of the tunnel under different working conditions.The main conclusions obtained are as follows:(1)Through the basic mechanical characteristic test of mudstone,the mechanical parameters and rheological parameters of mudstone are obtained,and the swelling law and rheological mechanism of mudstone after immersion in water are mastered.Based on the results of swelling test,it can be known that the mudstone is medium swelling rock;select creep based on the creep curve.Change the model,and use Matlab software for curve fitting to obtain creep parameters.(2)According to the problem of the initial support deformation during the actual construction process,the FLAC3 D numerical simulation software is used to carry out simulation research,and the expansion and creep effects are not considered,when only the expansion effect is considered,and when only the creep effect is considered.Research on the mechanical properties of tunnels.According to the numerical simulation results,there are two reasons for the large deformation of the tunnel: one is that the mudstone in the stratum has moderate swelling properties,which causes the deformation to increase;the other is that the rheological effect causes large deformation of the surrounding rock.In view of the large deformation of the tunnel,strengthen the support parameters.(3)In view of the long-term stability analysis of the expansive mudstone tunnel,the effects of rheological action on the initial support and secondary lining forces of the tunnel after strengthening the support parameters were calculated,and then the stress and deformation of the surrounding rock and lining of the tunnel were obtained.After only the initial support was constructed,the stress of the tunnel surrounding rock was too large for 9 months of rheological calculation;after the second lining was constructed,the stress gradually stabilized over time,meeting the requirements of tunnel construction.