| With the continuous development of road and railway,in the construction process encountered in the need to build a tunnel through the road section is also increasing.Broken water-rich rock tunnel is also becoming more and more common.Therefore,it is of great practical significance to study the construction of tunnels in broken water-rich rocks.First,the paper are summarized the research significance and research status of seepage flow in rich water tunnel;then,the engineering geological and hydrogeology of the Pu yajiao tunnel are summarized;and then,introduced the monitoring methods of YK217 + 660 section of Pu yajiao tunnel,and analyzed the monitoring results;After this a numerical calculation model based on FLAC3 D was established,the numerical calculation model simulated process of tunnel excavation,and compared the displacement and stress of the tunnel under the coupled condition of seepage and non-percolation;finally,compared the effects of Half-section grouting and full-section grouting on seepage coupling tunnel,and select the best of these tow ways.The main conclusions of this paper are as follows:(1)Analysis of influence of seepage coupling step on tunnel displacement by FLAC3 D,based on the actual construction conditions,it is concluded that 7500 coupling steps are reasonable under the current model condition.(2)Seepage has little effect on the displacement near the monitoring section,but the excavation of the vertical face near the impact of the largest displacement is relatively large,the impact ratio is around 20%.And seepage make the maximum displacement range is increased and the stability of the surrounding rock is weakened.The results of mechanical analysis are revealed the effect of seepage on the vertical maximum stress near the tunnel monitoring section and the excavated face is about 30%,while the effect on the horizont al stress is very small,which is only 1.5% near the excavated face.(3)Semi-section grouting has little control on the radial displacement of tunnel face,and the vertical displacement control force is also not strong,at about 10%;Full-section grouting has a significant effect on the vertical displacement and radial displacement of the tunnel,about 30% of the radial displacement and about 25% of vertical displacement.(4)About the influence of stress on the tunnel,the influence of half-grouting on vertical stress of tunnel is 20% greater than 10% of total grouting,but the effect of full grouting on the horizontal force of the tunnel is 30% greater than that of the semi-grouting.Because for the extent of the stress,the horizontal stress is a large one,so in short,from the point of view of reducing stress,the effect of full grouting on tunnel protection is better than half grouting.(5)Through a comprehensive analysis,in particular,the seepage is rich,the tunnel displacement is large,the lining is easy to crush the case of the proposed full-section injection method,but in the tunnel displacement is not large,lining is not easy to crush,but there are a small amount of seepage flow of tunnel construction and excavation progress of the case,from an economic point of view,half-section grouting can achieve the requirements. |
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