ABSTRACT: A huge landslide of about 30X10M on the Yangtze River, China, in 1985 is described. For the purpose of future safety forecast, monitoring system was installed on the sliding slope. Back analysis of the displace- ments measured by borehole inclinometer was conducted to set up mathematical model for forecasting the behavior of the slope. A new method of back analysis was developed, considering only the elastic part of the deformation. Overall elastic moduli of the sliding mass obtained in, the, back analysis are close to the rock-filling test results. The results of stability analysis by the obtained model are close. to those by Sarma"s method.
RESUME: Un grand glissement de terrain d"environ de 30 millions en 1985 sur le fleuve Yangtse en Chine est decrit dans le present article. Pour but de previsions en securite, un système de surveillance a ete installe sur la pente de glissement. Les inverses analyses des deplacements mesures par des inclinomètres dans des forages ont permis à etablir un modele mathematique de prevision de l"etat de la pente. une nouvelle methode des inverses analyses tenant compte seulement la part elastique de la deformation a ete formulee. Le module elastique et synthetique du bloc de glissement obtenu par les inverses analyses se rapproche des resultats d"essais dans te laboratoire. les resultats des analyses de stabilite du modèle susmentionne sont conformes à ceux obtenus par la methode de Sarma.
ZUSAMMENFASSUNG: Der Artikel hat etwa 30 Mill. M machtige Gleiten vorgestellt, der im Jahre 1985 im China an Yangtze Fluβ erfolgt. In Zukunft fuer Sicherheitsvoraussagen wurden Überwachungsanlagen in Gleitebene aufgestellt. Um mathematische Modell der Verhaltensvoraussagen in Böschung zu einrichten, haben Zurueckanalysen der Verschiebungen ausgefuehrt, die durch Bohrloch-Neigungsmesser gemessen wurden. Ein neue Zurueckanalyse Methode hal sich entwickelt und nur elastische Verformungsteil beruecksichtigt. Zurueckanalysen erlangen komplexe elastische Module der Gleitmasse Stabilitatsanalysen stimmen mit Sermamethode ueberein.
1. THE XINTAN LANDESLIDE In the early morning of June 12, 1985, a huge landslide with a t2tal volume of about 30X10M from an area of 1.1 KM occurred at a little town, Xintan, upstream from the planned damsite of the famous Three- Gorges Project on the Yangtze River, China. Large quantity of rock and earth slided down and fell into the river with a velocity of 10 to 30 m/sec. Gigantic waves up to 30 m high were raised and propagated for a distance of 10 km both ups team and downstream form the, town. The old Xintan town was destroyed completely, but owing to the successful forecast, the population was withdrawn from the town timely and no human life in the town was loat
1.1 Geology The landeslide area is located at the west limb of the Huangling anticline. The underlying bedrock formations are, from west to east, Silurian sandstone and shale, Devonian sandstone, Carboniferous limestone and Permian limestone and coal seams, dipping upstream at 25–38 and striking N10-,30 E, approximately perpendicular to the river. This is an area of torrential rain.