Study On The Mechanical Behavior And Stability Of Highway Tunnel Surrounding Rock In High-pressure Water-rich Area

In recent years, along with the rapid development of national economy,transportation construction also accelerates the pace of development in China. Inaddition, the strategies of Western Development and Central Rise promote a largequantities of railway and highway projects spring up like mushrooms. However, itis inevitable to pass some regions with abominable geologic conditions, such as weaksurrounding rock, high stress, fault zone, coal-bed gas zone, high water pressure andwater-enriched region during the process of project implementation.Moreover, withthe development of transportation construction, there are more and more railwayengineering projects through high water pressure and water-enriched region. Thefollowing three problems are undoubtedly become the main problems to build tunnelsin these regions: How to calculate external water pressure on tunnel lining? What isits distribution law? And what are the mechanical characteristics of support structure?It is sightless and quite unsafe to build tunnels in these regions unless the aboveproblems have been solved properly.Based on the Ba Taishan Tunnel on Cheng Wan highway, firstly, this articleanalyzes the reasonable scheme of Ba Taishan Tunnel on grouting and blocking waterin detail. And then it analyzes various factors which could affect external water onlining comprehensively. Furthermore, a numerical simulation recaptures theexcavation construction process of Ba Taishan Tunnel so that to explore the stabilityof surrounding rock and force characteristics of structure. Lastly, the paler mainlyresearches the variation of surrounding rock stress and the internal forcecharacteristics of external water pressure on the second lining under the situation thatcracking water load is existing on the water-rich section of Ba Taishan Tunnel, andproposes relevant optimization measures. And concluded that：①Water grouting must ensure that the grouting construction technology, andconstruction quality, so that the permeability coefficient of the grout K1/Kr <0.1,according to the actual situation the Grouting radius is selected2-5times to the tunnelradius;②The maximum stress of surrounding rock of the tunnel in High waterpressure rich water district appears at the foot of a wall location, and the increaseswith water pressure increasing; ③when the Supporting structure of the tunnel in High water pressure richwater districtin was under the effect of fracture water loads,the change of internalforces is very greatly, in addition the change of internal forces of corners is veryobvious.