Gradnja predorov v iztisljivih hribinah

magistrsko delo

Jaka Hrast (Author), Vojkan Jovičić (Mentor)

Abstract

Pri gradnji vseh vrst podzemnih objektov moramo najprej poznati primarno napetostno stanje ter nato prerazporeditev napetosti in deformacij v okoliški hribini. Obstaja več metod za določanje tega stanja, od osnovnih za krožno odprtino v elastičnem mediju, do bolj kompleksnih, ki upoštevajo tudi druge faktorje, ki vplivajo na prerazporeditev napetosti in nastanek deformacij. Pri iztisljivih hribinah je to še toliko bolj pomembno, saj prihaja do velikih deformacij hribine v izkopni prostor, katere lahko privedejo do porušitve podpornih elementov predora. Zato je izbira časa vgradnje podpornih elementov ena ključnih nalog pri načrtovanju predora v takšni hribini. Če elemente vgradimo prehitro, bodo napetosti nanje prevelike in bo tako prišlo do porušitve. V primeru, da elemente vgradimo prepozno, pa le ti ne bodo imeli velikega učinka na stabilnost predora. Pomembno je tudi, da izbiramo elemente z duktilnimi lastnostmi, da so sposobni prenesti večje deformacije, ne da bi prišlo do porušitve. Klasičen primer takšnega duktilnega podpornega elementa so deformacijski elementi, ki imajo sposobnost velikih deformacij (okoli 40% dolžine), preden popolnoma prevzamejo napetosti. Pri gradnji predorov v iztisljivih hribinah je pomembna tudi metoda gradnje. Najpogosteje je v svetu uporabljena nova Avstrijska metoda (NATM), ki narekuje gradnjo v odsekih in sprotno določanje količine in vrste uporabljenih podpornih elementov. Mehanizirane gradnje z TBM stroji se v iztisljivih hribinah praktično ne uporablja, saj se v primeru zaustavitve delovanja stroj hitro zagozdi. Poleg vsega naštetega pa je pomemben tudi monitoring predora, in sicer med samo gradnjo in tudi po koncu le te, saj le tako lahko zagotovimo ustrezno varnost obratovanja predora.

Keywords

podzemni objekti;iztisljive hribine;NATM;načrtovanje;

Data

Language:	Slovenian
Year of publishing:	2021
Typology:	2.09 - Master's Thesis
Organization:	UL NTF - Faculty of Natural Sciences and Engineering
Publisher:	[J. Hrast]
UDC:	622
COBISS:	67166979
Views:	311
Downloads:	53
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	English
Secondary title:	tunnel construction in squeezing ground conditions
Secondary abstract:	While constructing the underground excavation we need to know the primary stress field and also the stress and deformation redistribution in the surrounding rock mass. There are several methods to determine this redistribution, from the basic analytical methods for circular openings in the elastic medium, to the complex equations, which involve also other factors for determination of the stress redistribution and the formation of deformations. If the tunnel is being built in squeezing ground, we must pay an attention to much higher deformation, which can lead to support failure. This is why choosing the right support elements and the installing time of the support is crucial, while designing the underground object in squeezing ground conditions. If the support is installed to soon, then the high stresses on the tunnel lining will appear, which can lead to the support failure. If the support elements are installed too late, they will not have much effect in providing global tunnel stability. It is also important to choose ductile elements, which can take higher deformations without failure. Most common ductile support are yielding elements, which can take about 40% of deformation of its length, before they take the full support stress. The important element of tunnel construction in such conditions is also choosing the right excavation method. The most commonly used is New Austrian Method (NATM), which comprises a construction in phases and the in-situ determination of the installed support. Construction with TBM is mostly not used in squeezing ground, because in the case of a sudden stopping of drilling, the machine can be trapped in ground. Aside from that it is also important to perform monitoring of the construction of a tunnel and also to continue with it after the end of the construction, when the tunnel is in use.
Secondary keywords:	underground structures;squeezing ground;NATM;design;
Type (COBISS):	Master's thesis/paper
Study programme:	0
Thesis comment:	Univ. v Ljubljani, Naravoslovnotehniška fak., Oddelek za geotehnologijo, rudarstvo in okolje
Pages:	XIV, 54 f.
ID:	13028197