360℃ JET-GROUTED CONICAL CHAMBERS ALLOW SAFE TUNNELLING UNDER A RIVER WITHIN AN HIGHLY PERVIOUS ENVIRONMENT

摘要

The paper relates the crossing under the Tamandatuei river, in Sao Paulo city, through a pervious, submerged soil environment, that required an absolutely pioneer 360℃ jet-grouted pre-reinforcement shaped as a sequence of conical chambers, each one sealed at the far end by a jet-grouted septum. Difficulties in the control of the outflowing of the spoil material obliged to apply a specifically adapted "preventer valve". Owing to the success of this first case, the same type of reinforcement is presently in process in the Rio de Janeiro Metro.