Mechatnical Property And Construction Technology Study Of High-speed Railway Tunnel Invetr Lining Stucture

As is known to all, there is always exist some situations when associated with a highspeed railway tunnel project. Such as a big cross section, the complicated stress of tunnelstructure, especially the tunnel invert part is most complicate. When referred to the largecross section tunnel which can pass through the soft surrounding rock, the quality ofbuilding invert has significant meaning in the safety and durability of the tunnel liningsystem. The drawback of the traditional invert building method will make it difficult toimplement all of the standard、procedure and rule of the quality safety in railway buildingto the scene, so the full-breadth invert construction、invert quadric lining and filling theconcrete to pour into in more times have been the basic requirement in the high-speedrailway tunnel invert construction. As a result, some issues have been raised at homesuch as the mutual interference between the invert construction and driving face, the slowprogress of full-breadth pouring of the invert lining and the bad quality when takingshape. These issues have made the contradiction in the tunnel construction which usesthe drilling and blasting method more and more intense. The concept of the invertconstruction should be improved, and the construction technology and corollaryequipment which has the advantages of integrating tantalizations and mechanizationshould be the key and core in the invert construction development.At present, our solution to the inside hole traffic when making the full-breadthinvert construction mainly depend on the trestle, however, the convenience andfeasibility need to be improved. The invert lining pouring still adopt the traditional smallformwork or the steel formwork of the invert group, these tradition not only have towaste lots of steels, it also make installing、removing and revision become difficult, inaddition, the pouring quality is hard to guarantee. We are sure that invert construction hasbeen a controlling process in the tunnel building. To solve above puzzle, this text studythe mechanics character of tunnel invert lining and the rapid construction technology,finally we conclude as follows:(1)The invert setting can effectively control the value and coverage of rock massdeformation of the periphery of tunnels; it also can improve the stress situation of thesupporting structure, coordinate the distribution between the axial force and the bendingmoment of the supporting structure. Especially to be mentioned is that it can effectivelyrestrain the plastic zone of arch foot from expanding to the deep part of the rock. For thesake of express the insert’s function better, the invert should be closed with the lining onthe top to form a ring as soon as possible.(2)After the overbreak of the invert, a mishandle will weaken the insert’s supportforce to the upper structure greatly and will raised differential settlement of the tunnelstructure system. Then the stress concentration effect of the sidewall will aggravate andthe plastic zone of the rock will expand.(3)The underbreak of the invert will shift down the cross section where the bendingmoment of the tunnel’s supporting structure is maximum, the assail force will decreasefollowing with the shifting down of the cross section, all these results will increase theeccentricity of the cross section where the bending moment is maximum, it is not goodfor the load bearing of the supporting system. (4)After the invert concrete and the filling concrete are poured into molding just inthe same time, the majority structure of the filling concrete will bear the pulling stress,the pulling stress at centre ditch is as high as almost2.5Mpa. This stress state will makethe pull crack and destroy of some part easily, such as construction joint on the road andthe centre waterway, meanwhile the stress concentration effect of the invert and sidewalljoint will be more notable and the scope will be expanded.(5) If the insert’s length be excavated once exceed the distance which the tunnelliner zone effect can bear, serious situation will happen. First, bridge champions leagueaction of vertically and horizontally zone will weaken to disappear, the rock stress willredistribute rapidly, the prime support deformation will have a rapid increase, the scopeof plastic zone will expand significantly. In the end, the sidewall of the interface of theinvert begin excavate part and the invert already applied to section will be pulled cracksand drive the two sides of the support be destroyed and result a serious collapse finally.(6)The invert rapid construction formwork adopt the arch trestle which is separatingand has two-lane, this formwork give consideration to both the safety and economy, alsoit solved the mutual interference between the invert work and the working face tunneling;we use the end-beam design to separate the invert excavate and the invert filling into twooperation area to construct parallel, this method reduce the cycle operation time andimprove the construction efficiency totally.(7) The invert formwork design the move system according to the schedule of theinvert excavate at a time, it save the usage amount of reinforce rebar, solved someproblems such as install the formwork of the invert lining, difficulty of form removal, itmake the process of invert construction standard, strengthen the civilized constructionand the organization and management in the construction, it also avoid the violatecompasses operation in the construction.(8) The invert trestle is easy to install, it walk flexibly in the construction, and has astrong environmental suitability to the complicated construction site; the arch design ofthe trestle satisfy the span requirements as well as bring down the trestle’s deflectionwhich is most unfavorable loading, therefore has a higher security coefficient...