Dimenzioniranje cevnega ščita pri projektiranju predorov : magistrsko delo

Bolarič, Dejan (author), Logar, Janko (mentor), Klopčič, Jure (comentor)

Ena najpomembnejših zahtev pri gradnji predorov je varnost. S stališča varnosti je med gradnjo tveganjem najbolj izpostavljeno nepodprto območje pred čelom predora, kjer sveže izkopan prečni prerez še ni obložen s primarnim podporjem, armaturo in brizganim betonom. Na tem območju se pri gradnji v slabši hribinski masi za zagotovitev varnosti pri delovnem procesu in preprečitev pojava izpadanja klinov hribine vgradi začasni ukrep, imenovan cevni ščit. V inženirski praksi obstajajo nekatere metode za dimenzioniranje jeklenih elementov cevnega ščita, ki niso nujno optimalne. Na podlagi pomikov, merjenih s horizontalnimi inklinometri med gradnjo predora Trojane, je mogoče na diskretnih mestih ovrednotiti ukrivljenosti cevi, v katere so bili inklinometri vgrajeni. To se prevede prek teorije upogiba neposredno na račun obremenitve na element. V nalogi so predstavljene obstoječe deterministične metode za dimenzioniranje za oceno obtežbe na cevni ščit, za katere so podani dokazi, da so neekonomične. V namen optimizacije procesa dimenzoniranja je razvit nov, povsem empiričen postopek, temelječ na poznavanju dejanskega obnašanja predora brez pomembnejših predpostavk o materialu, obtežbi ali statičnem modelu. Vzorcu meritev se s prilagoditvijo funkcije pomikov priredi krivuljo časovnega razvoja radialnih pomikov, s katero so ocenjeni pomiki in obremenitve na nepodprtem območju pred čelom predora. Kot alternativa je iz literature povzeta metoda za dimenzioniranje po Pasternakovem modelu nosilca na elastični podpori. Obstoječe in nove metode so vgrajene v enostavne MATLAB programe oz. preglednice. Rezultati izračunov so primerjani z meritvami dejanskih profilov predora Trojane. Funkcija pomikov se izkaže kot najprimernejša metoda za dimenzioniranje cevnega ščita, saj se najbolj približa merjenim vrednostim, obenem pa zagotavlja tako varnost kot racionalnost.

• Language: Slovenian
• Keywords: predor, cevni ščit, dimenzioniranje, pomikovna funkcija, čelo predora, Pasternakov model, obremenitev cilindra, obremenitev klina
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FGG - Faculty of Civil and Geodetic Engineering
• Publisher: [D. Bolarič]
• Year: 2018
• PID: 20.500.12556/RUL-103025
• UDC: 624.19:69(497.4)(043.3)
• COBISS.SI-ID: 8562785
• Publication date in RUL: 13.09.2018

BOLARIČ, Dejan, 2018, Dimenzioniranje cevnega ščita pri projektiranju predorov : magistrsko delo [online]. Master’s thesis. D. Bolarič. [Accessed 18 May 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=103025

Secondary language

• Language: English
• Title: Pipe Roof Design Within Tunnelling Projects : master thesis

Abstract

Safety is one of the most important issues regarding tunnel construction. During the construction, the highest degree of collapsing risk is present in the unsupported area in front of the tunnel's working face where the newly dug cross section hasn't been supported yet. In order to provide safe working environment and withstand falling out of blocks, a temporary support measure called pipe roof is bored into the working face surface. Within the tunnel constuction technology, various methods are being used to design the load-bearing steel elements, but they are not necessarily optimal. Based on the in-situ measured displacements obtained during the construction of Trojane tunnel, it is possible to assess the curvature of constructed pipe roof. These values are transferred to bending moments along the element. In the thesis, the existing methods of design are presented, yet proven to be uneconomical. Therefore, a new empirical method which considers real deformational behaviour of tunnel is developed based on the determination of the displacement function. A specimen of measure values is used for curve fitting. Thus, a uniform function of displacements can be used to calculate bending moments without any major assumptions of material, load or statical model (as opposed to existing methods). As an alternative, a method based on the Pasternak's model of a beam on the elastic support is studied. Both existing and newly developed methods are programmed in the MATLAB environment to enable the comparison of design values with the measurements from the Trojane tunnel. Empirical method using the displacement function theory is proven to precisely approach measurements and thereby assure both the safest and the most economical way of designing the pipe roof.

• Keywords: tunnel, pipe roof, pipe umbrella, design, displacement function, working face, Pasternak model, silo pressure, wedge pressure