Research On Action Mechanism Of Initial Shotcrete Layer Reinforcement To Tunnel Surrounding Rock Masses

Our nation is in high economy epoch,infrastructure construction occupies animportant place in national economy.Tunnel engineering and undergroundengineering is widely used ,technic of tunnel engineering and undergroundengineering is given prominence to many technical fields in civil engineering.Thispaper takes the tunnel rock masses and shotcrete layer as researchsubjects.,propoundarea-judgement method for finite rock blocks,introduce two dimension network ofcrack into distinct element model of underground engineering,study on actionmechanism of initial shotcrete layer reinforcement to tunnel sourrounding rockmasses in different cracks condition.Respectively ,some aspects are studied asfollows:.1 The actual state of tunnel constrution and the research methods of undergroundstabilityisintroduced.2 Geometric characters and mechanic characters of rock crack isintroduced,also,themethodofsimulatingthenetworkofcrackisintroduced.3 Propound the area-judgement method for finite rock blocks in network crackrock .after ledge excavation,use the character of the area of ployhedron'scross-section is lower than the basal face to make a judgement .wether rockblockisfiniteornot. .4 Use a rock tunnel model in simple crack conditon to primary study theshotcrete's support effects influence bychanging of cohesion,angle of internalfriction of shotcrete's interface and the shotcrete layer's thickness. when thecohesion and angle of internal friction is fixed ,the layer failure area becomessmaller with increase of shocrete layer's thickness.also the shotcrete layer has acritical thicknesswith the change of cohesion and angle of internal friction ofshotcrete'sinterface.5 Use two dimension network crack into a tunnel distinct element model.Take ahighway tunnel as background ,in different crack condition ,primary study theshotcrete'ssupporteffectsinfluence bythechangeofcohesion,angleofinternalfriction of shotcrete's interface and the shotcrete layer's thickness.In tunnelengineering ,chean rock masses and change the concrete characters to improvethe contact between rock masses and shotcrete layer ,and it maybe improvetunnelstability.