A large landslide in Zigui County, Three Gorges area

Abstract

On 13 July 2003, a landslide with a volume of approximately 20 × 106 m3 occurred on the left bank of the Qinggan River, Zigui County, Hubei Province, China. As a result, 14 people died and 10 people are missing. A landslide dam was formed, blocking the Qinggan River. A channelized diversion was constructed for prevention of upstream flooding and damage downstream caused by dam breaching. The landslide was a typical translational rockslide in weathered shale and sandstone, a block of which slipped down along the bedding plane. It is estimated that the landslide was caused by the combined effect of the following factors: (i) a bedding plane between incompetent weathered shale and competent sandstone that daylights at or is shallowly buried at the bottom of the Qinggan River; (ii) a thin layer of clayey soil acting as the slip plane that is likely a preexisting shear surface; (iii) excavation of the shale as raw material for brick fabricating on the slope; and (iv) a combination of prolonged rainfall and reservoir impounding.Key words: landslide, landslide dam, rainfall, impounding, Three Gorges area.

Landslide Model Test System and Its Application on the Study of Shiliushubao Landslide in Three Gorges Reservoir Area

“…The rainfall intensity was simulated according to Fig. 10, and there was heavy rainfall when the water level was 135 m (Dai et al, 2004). Finally the reservoir drawdown was simulated.…”

“…As reservoir impoundment will raise the water level rapidly and disturb the balance of the geology, it is anticipated that the impoundment of the Three Gorges Reservoir may cause further landslides and rockfalls, as well as erosion of the reservoir bank. Many slopes began to deform with noticeable magnitudes after theˆrst stage of impoundment in 2003 to July 11) (Dai et al, 2004), while the average rainfall in the area is 1200 mm per year. As the water level of the Three Gorges Reservoir reached 156 m in 2006, and 175 m (the designed water level) in 2009, the frequency of landslides and rockfalls of the Three Gorges Reservoir area increased further.…”

The Monitoring-Based Analysis on Deformation-Controlling Factors and Slope Stability of Reservoir Landslide: Hongyanzi Landslide in the Southwest of China

“…The large landslides of the sizes greater than ten million cubic meters were normally triggered by the rapid declination of the reservoir water level. Also, approximately 75% of triggered landslides were due to the revivification of ancient landslides [5]. In summary, the significant and instant reservoir water level fluctuations normally cause negative influences on the global stability of the reservoir slopes through influencing their hydrological conditions and reducing the slope strength [6].…”

“…The failure mechanisms and resulted chain of disasters (such as the impulse of wave) by reservoir landslides have been extensively studied in previous studies [5][6][7]. Erosions of loose debris at the slope toe by flow, instant pore water pressure generation in the slope by the drawdown of reservoir water level, and structural and strength reduction of the hydrofluctuation belt are the main reasons of triggering reservoir landslides [1,[4][5][6].…”

“…Erosions of loose debris at the slope toe by flow, instant pore water pressure generation in the slope by the drawdown of reservoir water level, and structural and strength reduction of the hydrofluctuation belt are the main reasons of triggering reservoir landslides [1,[4][5][6]. By conducting numerical analysis [6,7], the risk management of potential impulse wave by the slope movement also draws more attentions.…”