Design And Analysis Of The Cover Structure To The Supper-shallow-burial Undergroud Engineering

Excavating in super-shallow-burial underground engineering under way, oftenuses advanced support and primary support of reinforcement method for thesurrounding rock of underground engineering, especially for the top rock, to keep thestable and do not produce big deformation, so that the top rock can bear the weight ofsoil and pavement above the role of vehicle load. But, because of poor condition ofrock, thin cover earth thickness and a lot of underground pipelines, just like that manyof the factors such as adverse effects, ahead of supporting and primary support can’teffective implementation, or the strata of reinforcement bearing capacity still notenough to resist the role of the upper strata and load, causing the road surface collapse,endangers security or bring losses of lives and property. At present to reduce vehicleload for underground structure of influence the main means was laying20mm steelplates, But because of the thickness steel, small bending stiffness, so it limits the roleof decentralized load. Therefore, this paper put forward a kind of the steel skeletoncover structure to spread the influence of vehicle load, and research the coverstructure of the scattered loads.Basic Theory of Elastic Foundation Beam, the moment of inertia of the coverstructure should be increased. So a standardized and modular steel skeleton coverstructure for building a temporary road quickly is devised. This structure canreplace the original laying of steel plate cover structure. and it has applied forthe national patent, and the patent application number is:201110460705.8. Based onTheory of Elastic Foundation Beam, the factors of load-spreading for the coverstructure will be analyzed. From that we will know that the changes of the moment ofinertia of the cover structure and laid section of seat of the cover structure foundationbed coefficient have great effect on underground engineering. Basing on the exampleof Beijing subway line4, Xidan station2、3#tunnel entrances, It calculates theinfluence of the underground structure that the vehicle load gives in different coverstructures by Theory of Elastic Foundation Beam. The last a2d-nonlinear-finiteelement model will be established by using the ABAQUS in this paper, it simulatessuper-shallow-burial underground tunnel cover structure， and thesuper-shallow-burial underground tunnel which laid20mm or40mm or60mm steelplate and steel skeleton so as to learn how the vehicle load super-shallow-burialtunnel influence the underground structure and learn how the steel frame structurescatter and weaken the influence of the vehicle load.The main conclusion and results are as follows:(1)this paper first put forward thesteel skeleton cover structure, and applied for a invention national patent and a utilitymodel patent, patent number:201110460705.8and201120575138.6.(2) Know thethe Influencing factors of spreading loads, the foundation of the force with structure moment of inertia decreases, along with the bed of the coefficient increases.(3) In theauxiliary measures of the cover structure, relative to the20mm steel plate structure,the road of the maximum pressure to reduce80%.(4) Using the numerical simulationmethods, draw the tunnel under protection of steel skeleton cover structure, vehicleload produced the surface subsidence than uses the steel plate can reduce about75%.