Vpliv koeficienta razbremenitve na napoved konvergenčnih pomikov v predorih : magistrsko delo

Vogrinčič, Rok (avtor), Jovičić, Vojkan (mentor)

V novejšem času pridobiva izraba podzemnega prostora vedno večji pomen in vse pogosteje se dogaja, da zato predorogradnja posega v geotehnično zahtevna območja s slabo nosilno in močno deformabilno hribino. Zato je za projektanta predhodna napoved konvergenčnih pomikov izrednega pomena, ker na podlagi tega določi velikost deformacijske tolerance, za katero je treba izkopne profile povečati, hkrati pa omogoča varno in gospodarno gradnjo. V magistrskem delu je opisana in uporabljena metoda kontrole konvergenc, ki je ena od uveljavljenih tehnik za načrtovanje predorov, bazirana na analizi interakcije konstrukcije in hribine. Preučene so obstoječe rešitve avtorjev, ki ponujajo zaključene enačbe za napoved konvergenčnih pomikov. V nadaljevanju je bila po analitični poti narejena primerjalna študija vpliva izbire enačbe na vrednost koeficienta razbremenitve. Tu smo se omejili na enačbo Hoeka in rešitev, ki jo predlagata Vlachopoulos in Diederich. Isti postopek smo na koncu ponovili še z uporabo numeričnih orodij (Plaxis 2D) in ga primerjali z rezultati, dobljenimi po analitični poti. Pokaže se, da velikost koeficienta razbremenitve in konvergenčnih pomikov naraščata skupaj z velikostjo cone plastifikacije, ki se formira pri polnem izkopu, zato je enačba Vlachopoulosa in Diedericha primernejša izbira od Hoekove, ker poleg oddaljenosti od čela upošteva tudi velikost radija plastičnosti. Prav tako kaže na dobro ujemanje s Panetovo enačbo, ki opisuje elastično obnašanje. Zanimivo je območje radija plastičnosti 2 < Rp/R < 3, kjer dajeta obe enačbi zelo podobne rezultate, kar vodi do zaključka, da je uporaba Hoekove enačbe omejena na to območje, v ostalih primerih pa je bolj primerno uporabiti rešitev Vlachopoulosa in Diedericha.

• Jezik: Slovenski jezik
• Ključne besede: predori, metoda kontrole konvergenc, koeficient razbremenitve, Plaxis 2D
• Vrsta gradiva: Magistrsko delo/naloga
• Tipologija: 2.09 - Magistrsko delo
• Organizacija: FGG - Fakulteta za gradbeništvo in geodezijo
• Založnik: [R. Vogrinčič]
• Leto izida: 2017
• PID: 20.500.12556/RUL-99021
• UDK: 624.19(043.3)
• COBISS.SI-ID: 8259425
• Datum objave v RUL: 21.12.2017

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Influence of the stress release coefficient on tunnel convergence : Master thesis

Izvleček

The use of underground space is getting more and more importance across the whole world. Besides modern industrial society is becoming more and more dependent on transportation infrastructure which leads to increase of need of tunnel construction. Because of that engineers are often forced to design tunnels in difficult geotechnical conditions in weak rocks where large deformations occur. Thus it is very important for engineer to correctly predict the convergence movement, that will occur during the construction. On the basis of this the deformation tolerance is determined. In this paper convergence-confinement method is described and further used to examine the effect of longitudinal displacement profile on the stress release caused by tunnelling. Thereby, a closed form solution from Hoek and Vlachopoulos and Diederich were compared and analysed. Firstly, a comparison was made by an analytical approach and further compared with numerical analyses, which were carried out using Plaxis 2D software. Analyses showed that the stress release coefficient and convergence movement increases with the size of plasticity zone that develops in full excavation. Based on that the Vlachopoulos and Diederich solution is more appropriate that the one Hoek suggested, because besides the distance from the tunnel face it also takes into account the radius of the plasticity zone. Besides, it also showed good results when compared with Panet solution for elastic behavior. Interesting part is the plasticity area 2 < Rp/R < 3 where both of the solutions give very similar results. This leads us to the conclusion that Hoeks equation should be used only when working in these conditons, otherwise is more appropriate to use Vlachopoulos and Diederich solution.

• Ključne besede: tunnels, convergence confinement method, stress release coefficient, Plaxis 2D