Stability Analysis Of The Hua Du ? Tunnel Entrance Slope Under The Action Of Blasting And Rainfull

With the acceleration of human engineering activities,in the process of tunnel excavation under the complex geological conditions of highway or railway area,especially in the south,long-term rainfall and blasting vibration are easy to cause the slope sliding and collapse above the tunnel entrance section.Therefore,it is necessary to analyze the deformation and stability of the slope above the tunnel entrance under the action of blasting vibration and rainfall.huadu ? tunnel in right hole entrance section slope as the research object,on the basis of analysis on related data at home and abroad,according to the site engineering geological survey and construction situation is summarized,the main factors that influenced the stability of huadu ? tunnel in right hole was analyzed through field monitoring and numerical simulation of tunnel in right hole entrance section slope stability analysis under the action of blasting and rainfall.The research results include.(1)based on the analysis of the engineering geological conditions of the slope at the entrance of the tunnel,it is proposed that the factors affecting the slope stability include internal factors and external factors,among which the internal factors mainly include topography and landform,geological structure and stratum and rock mass structure,etc.External factors mainly include damage cracks and perturbations of slope rock mass structure caused by tunnel blasting vibration.At the same time,under the action of rainfall,the surface seepage formed by rainwater on the slope is easy to lead to the instability of the slope at the entrance of the tunnel.(2)The surface subsidence displacement and vibration velocity of blasting vibration of the slope above the entrance of the tunnel were monitored.For each heading to X,Y and total speed of vibration monitoring data through the optimized Steve sadove experience attenuation formula fitting,get left,right and gate is the largest single ring blasting quantity is 3.750 kg,3.696 kg and 4.220 kg respectively similar to numerical value,but also puts forward the suitable for the tunnel slope blasting vibration attenuation formula of experience.(3)Numerical software midas-gts-nx was used to simulate and study the related laws of the measured points of the tunnel slope under the action of blasting vibration and rainfall,such as the velocity,displacement,maximum blasting charge of each single section of the guide pit,slope safety coefficient and slope stress and strain,etc.,so as to obtain the region and intensity of the influence of different blasting and rainfall of the guide pit on the disturbance of the upper slope.The blasting vibration of the left guide pit has the greatest influence on the slope body.Compared with continuous rainfall for 2h,the slope displacement increased sharply after 4h of continuous rainfall,and the slope safety coefficient was lower than 1.30 after 6h of continuous rainfall.Under the effect of blasting vibration with rainfall,slope displacement and effective plastic strain value higher than that of slope under blasting vibration or only rainfall condition,compared to only subjected to rainfall is 2-3 times higher,and the blasting and continuous rainfall 4 h and 6 h under the slope stability safety coefficient are less than 1.10 to induce slope instability,late is bad for the smooth excavation of the tunnel.The above research results can provide references for similar projects in the later stage.