New analytical approaches for evaluating the performance of systematic pre-tensioned fully grouted rockbolts in tunnel stabilization

• Autorzy: Ranjbarnia M. , Fahimifar A. , Oreste P.

Identyfikatory

DOI

10.1515/amsc-2016-0056

Warianty tytułu

PL

Nowe analityczne metody oceny skuteczności działania wstępnie naprężanych zacementowanych kotew przy stabilizacji tuneli

• Języki publikacji: EN

Abstrakty

EN

In this paper, two new analytical approaches are presented on the basis of convergence-confinement method to compute both the ultimate convergence of circular tunnel and its plastic zone having been reinforced by systematically pre-tensioned fully grouted rockbolts. The models have two basic assumptions: (1) the grouted rockbolts increase the radial internal pressure within a broken rock mass by both the pre-tensioned force and the probable following induced force due to rock mass movement (2) tunnel convergence (specially short-term) occurs only due to reducing and diminishing of the radial constrained stress on tunnel surface provided by the working face. Hence, the values of both the pre-tensioned pressure and the mentioned radial constrained stress are specially taken into consideration in this paper. That is, according to their magnitudes, two different conditions occur: the magnitude of pre-tensioned pressure is greater than that of the constrained stress at bolt installation time and vice versa. The solutions are extended to each of conditions, and illustrative examples are solved. The proposed approaches predicting almost identical results show that pre-tensioning of grouted rockbolts will increase the efficiency and effectiveness of rockbolts.

PL

W pracy tej przedstawiono dwie analityczne metody oparte na metodzie badania konwergencji i naprężeń wymuszonych wykorzystane do obliczania zarówno granicznej konwergencji tunelu o przekroju koła oraz zachowania strefy plastycznej, po wzmocnieniu tunelu za pomocą wstępnie naprężanych i zacementowanych kotew. Model opiera się dwóch założeniach: (1) zacementowane kotwy prowadzą do wzrostu ciśnienia wewnętrznego w kierunku promieniowym w kruszonym materiale skalnym, spowodowanego siłą wstępnego naprężenia oraz siłą spowodowaną przez ruchy górotworu; (2) – konwergencja tunelu (zwłaszcza w ujęciu krótkoterminowym) pojawia się jedynie wskutek zmniejszenia wymuszonego naprężenia promieniowego na powierzchni tunelu generowanego w rejonie przodka wydobywczego. W metodzie zwrócono szczególną uwagę na wartości ciśnienia wstępnego naprężenia jak i naprężenia wymuszonego. W zależności od wielkości tych naprężeń mamy do czynienia z dwiema zupełnie odmiennym sytuacjami: wielkość ciśnienia wstępnego naprężenia jest większa niż naprężenia wymuszonego w trakcie mocowania kotew, lub odwrotnie. Podano rozwiązania dla obydwu rozważanych przypadków i zaprezentowano przykłady. Prawie identyczne wyniki otrzymane przy użyciu obydwu metod wskazują, że wstępne naprężenia cementowanych kotew poprawia ich skuteczność działania.

Słowa kluczowe

EN

analytical approach; tunneling design; calculation method; convergence-confinement method; pre-tensioned fully grouted rockbolt

PL

metody analityczne; projektowanie tuneli; metoda obliczania; konwergencja; naprężenie wymuszone; wstępnie naprężane zacementowane kotwy

• Wydawca: Instytut Mechaniki Górotworu PAN
• Czasopismo: Archives of Mining Sciences
• Rocznik: 2016
• Tom: Vol. 61, no. 4
• Strony: 823--852
• Opis fizyczny: Bibliogr. 36 poz., rys., tab., wykr.

Twórcy

autor

Ranjbarnia M.

• University of Tabriz, Faculty of Civil Engineering, Department of Geotechnical Engineering, East Azerbaijan, Tabriz, 29 Bahman Blvd, Iran

autor

Fahimifar A.

• Amirkabir University of Technology (Tehran Polytechnic), Faculty of Civil and Environmental Engineering, Department of Geotechnical Engineering, Tehran, Hafez Ave, Iran

autor

Oreste P.

• Politecnico di Torino, Faculty of Environmental, Land and Infrastructure Engineering, Turin, Corso Duca Degli Abruzzi, 24, 10129, Italy

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