| Relying on the Xiao Batian tunnel in Guizhou province LiuPanshui City which is a cavetunnel used for highway and Combined with theoretical analysis and numerical simulation,this thesis carries out a study on the stability of the surrounding rock and supporting structuresafety of the cave tunnel’s construction and operation from the static construction, the blastingconstruction, the earthquake response and the vehicle vibration response.The main research contents and outcomes were gained：(1) The step construction of the Xiao Batian tunnel is simulated by ANSYS finiteelement software. Combined with the surrounding rock stress, the plastic zone of thesurrounding rock, lining deformation, lining stress, the lining safety coefficient and the liningcracking coefficient proposed by Griffith criterion, the stability of the surrounding rock andsupporting structure safety of the cave tunnel’s construction are analyzed. The results showthat all the results meet the standard. The surrounding rock and the support structure of theXiao Batian tunnel is stable and safe during the construction.(2) Based on the model and engineering geological conditions of the Xiao Batian tunnel,the influence of different distribution cave on the stability of tunnel surrounding rock andsupporting structure is qualitatively analysed. The cave in tunnel side as the most unfavorabledistribution influencing on tunnel surrounding rock and supporting structure is determinedfrom the aspects of the surrounding rock plastic zone, displacement of feature points, liningstress and lining safety coefficient.(3) According to that the side of the cave is the most unfavorable position of the biggestinfluence on tunnel surrounding rock and supporting structure, introduced the hole diameterratio λRand the spacing ratio KR, the influence of the distance and size changes of the cave onthe stability of tunnel surrounding rock and supporting structure is quantificationally analysedby the methods of numerical experiment. The influence of cave on the tunnel increases withthe increment of the hole diameter ratio λRincreasing, and decreases with the increment of thespacing ratio KR. When the hole diameter ratio λRis smaller than0.217, the cave on the tunneleffect tends to not cave, tunnel design and construction can not be considered it. When thespacing ratio KRis greater than1.419, the influence of cave on the tunnel tend to be stable.(4) Referring to relevant literatures, Taking the blasting vibration velocity, each particleextreme stress of the cave during the blasting and the blasting damage index BDI as the safetystandard, the blasting construction of the Xiao Batian tunnel is simulated by ANSYS finiteelement software. Using the maximum vibration velocity13.74cm/s, the maximum tensilestrength of2.13Mpa, the maximum compressive strength of23.25Mpa, the blasting damageindex BDI≤1to judge the stability of the cave during the blasting construction of the Xiao Batian tunnel. The results show that all the results meet the standard and the cave is stable inthe process of blasting construction(5) Based on the dynamic calculation model and engineering geological conditions of theXiao Batian tunnel, the influence of the blasting construction on the cave which has differentlocations such as top, bottom and side of the tunnel is analysed from the aspects of themaximum vibration velocity, the maximum tensile stress and the maximum blasting damageindex. The results show that the cave at the bottom of the tunnel is the most unfavorabledistribution as the biggest influence of blasting construction of the caves during the blasting.(6) The cave at the bottom of the tunnel is the most unfavorable distribution. from theaspect of distance between the cave and the tunnel, the fitting relationship between thedistance and the maximum vibration velocity is that v=88.187x-0.797, And the safe distancebetween the tunnel and the cave is1.15D buring the blasting construction.(7) Selecting of EL-Centro seismic wave after baseline correction and filtered, thedynamic calculation model of the Xiao Batian tunnel applied EL-Centro wave accelerationload, the laws of vibration displacement under seismic load of tunnel and cave feature pointsare analysed and the safety of the cave and the lining is judged by the standard of themaximum tensule, compressive stress and the stress increment. The results show that in theearthquake, the maximum tensile stress of the lining is0.752Mpa, the maximum compressivestress of the lining is2.450Mpa, the maximum tensile stress of the cave is0.169Mpa, themaximum compressive stress of the cave is2.126Mpa. All the results meet the standard andthe tunnel is no pull and fracture failure under seismic action.(8) With applying the EL-Centro acceleration wave,the finite element model wereestablished, where the locations of the cave were in the top, side and bottom of the tunnel.Compered with the displacement and velocity of the characteristic points, the circumferentialprincipal stress and the maximum increment of the principal stress of the cave and the lining,the results show that the cave at side of the tunnel is the most unfavorable position.(9) With the dynamic calculation model of the Xiao Batian tunnel, the vehicle load isconsidered as the exciting force function. The dynamic vehicle load response of the tunnel issimulated and the safety of the cave and the lining is judged from the aspects of the maximumvibration velocity, the maximum stress and stress increment. The results show that the effectof vehicle load on the tunnel and the cave is very small and the lining structure and the cave isnot failure under vehicle load. |
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