Emergency Stabilization of Fountain Slide to Maintain CN Rail Service
(Room Sagamore 1)
19 Sep 17
8:30 AM
-
9:00 AM
Tracks:
AREMA Technical Sessions- Track
Fountain Slide, located approximately 16 km Northwest of Lillooet BC, is a relic landslide that has been active since the 1970’s. The progressive movements have posed a significant challenge to BC 99, the main North-South highway in the region. The slide began impacting train operations of the British Columbia Railway Company (BCR) in the 1990’s. In 2004 the Canadian National Railway Company (CN) acquired BCR and undertook measures to stabilize the railbed during the following 11 years. Some of these measures included a track realignment, shotcrete tie back wall and a soldier pile and lagging wall with three levels of anchors. For many years the measures had proved to be successful, until in mid 2014 it was observed that the retrogressive slide activated two blocks uphill of the tracks. Slide movements were typically 6 mm per day, leading to extreme distortion of the earth retention system and frequent realignment of the tracks. In the summer of 2016 a design build system of micropiles and anchors was implemented to stabilize the slide. The approach was used because of limited access for large equipment and the need for a ductile stabilization system because of the ongoing movements during construction. Movements were as high as 20 mm/day during construction but continued to decrease during and after construction and the tracks appear to have been stabilized. The longevity of the stabilization is uncertain because of the magnitude and nature of the relic slide. The presentation will discuss the design considerations and final approach implemented, construction activities, and deformation monitoring during and post construction.