Abstract: In a method of constructing a reinforced concrete work such as a road tunnel, an underground gallery or a tunnel for an underground railway, there is first excavated an open trench 62 in which there are then placed, consecutively and contiguously, prefabricated hollow concrete frame element 4, the external faces of which have reinforcements 5. A filler concrete 18 is then poured so as to cover the joints between elements and to cooperate with the reinforced concrete of the frame elements and with the reinforcements so as to construct, by consecutive stages and rapidly, a monolithic work. The strength of this monolithic work is appreciably greater than the respective strengths of the prefabricated elements initially placed and of the filler concrete. Finally the trench is filled. Preferably the external reinforcements 5 of the frame elements are such as to cooperate with the filler concrete which is subsequently placed round the elements.