Multiple methods such as geological and geophysical prospecting, experimental study and numerical analysis have been employed to investigate the mechanical behavior of the rockmass in the central barrier between the temporary sbiplock and the sbiplift of the Three Gorges Project (TGP). Main results are as follows:
there exists an inverted ‘U’ shaped disturbed zone in the middle and upper parts of the barrier due to the effects of blasting and stress relief,
the disturbed rock mass differs from the original one in that its joints open and its rock blocks slide along the primary structural planes with the mechanical properties of the rock blocks unaffected basically and no secondary structural planes generated,
the scope and shape of the disturbed zone are well coincident with those of the damaged area of tension and shear.
Beaucoup de methodes telles que l'exploration geologique et geophysique, l'etude experimentale et l'analyse numerique ont ete employees pour examiner les proprietes mecaniques de la masse de roche dans la barrière centrale entre l'ecluse temporaire et le ascensseur dans le Projet de Troie Gorges. Les resutats principals sont donnes dessous. Ily a une Zone derangee en U inverse au milieu et à la part plus elevee de la barrière à cause de l'effet de l'explosion et la relaxation de contrainte. La difference de la masse de roche derangee à la masse originaire reside en ceci que les crevasses ouvrent, les blocs de roche glissent sur les plans structuraux primaires, les propietes des blocs de roche ne changent pas beacoup, et il n'y a pas les plans tructuraux secondaire qui se forment. Le domaine et la forme de la zone derangee coincident avec ceux de la zone derangee de traction et cissaillement.
Verschiedene Methoden wie geologische und geophysikaIische Erkundungen, Experimentaluntersuchungen und numerische Simulationen wurden eingesetzt um die mechanischen Eigenschaften des Gebirges im,mittleren Barrierebereich der temporaren Schleuse zu erklaren. Die Hauptuntersuchungsergebnisse sind:
im mittleren und oberen Bereich der Barriere existiert eine verkehrte U - foermige Spannungszone wegen Spreng und Spannungsabbau;
in dieser sekundaren Spannungszone ist das Gebirge aufgelockt und die ‘Key Block’ - Verschiebung ist möglich, aber die Formation vom neuen Rißist unwahrscheinlich;
die Auflockerungszone stimmt mit der Versagenszone von Zugspannung und Scherspannung ueberein.
The navigation structures in TGP comprise three parts, viz., the permanent ship lock, the temporary ship lock and the ship lift, all located in the left bank of the Changjiang River. The permanent ship lock is 5-stage double-way one, and the effective size of each chamber measures 280x34x5m (length × width × water level). The shiplift is of one-way single stage type with ship container size of 120x18x3.5m. And the one-way single stage temporary shiplock has effective size of 240x24x4m.
All these navigation structures are formed by deep excavation in rock mountains. For the permanent shiplock, the maximum excavation depth is 174.5m, and for the temporary shiplock and the shiplift 125m. The excavation started in April, 1994, ended in September, 1996 for the temporary shiplock and the shiplift, and a rock barrier has been formed between them, measuring 16 ~ 23m wide and 23 ~ 36m high (Fig. 1). The permanent shiplock is still under excavation, and according to design, a rock barrier, measuring 55 ~57m wide and 50~70m high will also be formed between the two ways of it Such giant barriers are rare in the history of hydraulic construction.
