Bowing
The Landslide Blog is written by Dave Petley, who is widely recognized as a world leader in the study and management of landslides.
I recently came across an interesting paper in the Bulletin of Engineering Geology and Environment (Hu et al. 2024) that explores the prediction of the time to failure of large slopes in an open pit coal mine in China. The paper is focused on the Fushun west open pit mine (Fushun West OPM), located in Fushun City in Liaoning Province. This is an astonishing site, the largest open pit mine in Asia, extending over a distance of 6.6 km from east to west and 2.2 km north – south. The mine is up to 420 m deep.
At the Fushun West OPM, slope failures have been a regular, and large-scale, problem. The paper features three case studies in which Hu et al. (2024) seek to understand the viability of time to failure prediction for the open pit wall slopes. They have documented a large number of failures, starting from 1927.
One of the interesting aspects of this site is that there is a good archive of Google Earth imagery. This provides interesting insights into the progression of failure. One landslide in particular captured my attention, located at [41.8468, 123.8840]. I first wrote about this back in 2022, but it is interesting to look at the progression of failure in more detail.
The first Google Earth image that captures this landslide, located on the northern wall of the Fushun West OPM, is in May 2014:-
At the time that this image was collected, this slope failure was about 340 m long. There is a further image in November 2014, which slows that the landslide had started to retrogress, and that the toe of the slide had extended into the pit:-
By October 2016 the situation with this slope had deteriorated considerably. The failure had extended laterally to a very significant degree, and there was considerable retrogression:-
The scale of the landslide at this point was remarkable – it was about 900 m from the crown to the toe and 600 m wide at the midslope point. The landslide had retrogressed to the top of the pit wall, and was threatening buildings and roads on around the mine.
By August 2017, the slope had retrogressed further, and was causing substantial damage to infrastructure around the mine:-
It’s clear that at this point considerable engineering work was being undertaken to try to arrest the failure, and the problem did not get any worse thereafter.
This is really great case study of the way that a comparatively small initial failure can turn into a major issue if it is not addressed at an early stage.
Interestingly, Hu et al. (2024) note that landslide occurrence at the Fushun West OPM peaked in the period between 1980 and 2000, but has reduced since. Presumably, this is an indication that management of the slopes improved in recent years.
Reference
Hu, J., Sun, S., Li, Y. et al. 2024 Landslide failure time prediction with a new model: case studies in Fushun west open pit mine, China. Bulletin of Engineering Geology and the Environment 83, 411. https://doi.org/10.1007/s10064-024-03902-8
