The Study On The Treatment For Yangqiaoba Tunnel Water-eroded Cave

Karst area of3.65×10km area in China,of the total land area of1/3,is the world’s most developed countries in the world karst.Effects on the stability of karst foundation have a greater impact,in the use of rock foundation (including caves) as a foundation bearing layer,the stability of rock foundation is particularly critical and important.The influence of karst cave on the tunnel mainly for:①tunnel surrounding rock deformation, instability often lead to tunnel collapse, rockfall locally,②the karst watennot only affect the construction,but also directly endanger the safety of personnel and equipment..Makes the existence of the cave tunnel stability becomes complicated, and this influence with the cave type, size, spacing, orientation changes. Therefore, the karst tunnel simulation is necessary.In this paper put forward two major categories of six treatment schemes for the Large cave of high-speed Yangqiaoba tunnel project,which includes:①tunnel right line. remain unchanged,left line shift left(after the new cave)②tunnel right line. remain unchanged left line shift left(bypass the new cave)③tunnel leftt line.shift right,right line remain unchanged(spacing of4.6m)④tunnel leftt line.shift right,right line shift right(spacing of20m)⑤the open cut tunnel⑥backfill excavationFirst,using the analytical method for the stability of the cave roof checking and estimate the approximate range of collapse Use large finite element analysis software to finite element for second and fourth schemes,Consider the construction is completed in the right holes in the case, the left hole on the right tunnel construction safety implications,and combining with the design rationality,construction safety,operation safety,engineering cost and construction period and other factors considered.The selected control scheme finally.