CHRISTOPHER BUIILDING, HILD BEDE COLLEGE, DURHAM
On the northern slope of an arm of the loop in the River Wear, Durham City, sits the College of St. Hild and St. Bede (of which I am a member!), a college of the University of Durham.
In 1965/'66 there was a winter of very heavy rainfall and the caps of the piles beneath the Christopher accomodation block began to be exposed. It was also evident that some trees had been dragged downslope, and superficial cracking was observed inside the building.
Construction of the block had caused failure of the slope, and the piles had been placed in postitions which meant they were in fact "stitching" across a failure surface. Hence, the piles were subjected to high shear stresses.
The average slope of the ground towards the river was approximately 1 in 4, and the geology of the ground was a granular mass overlying laminated clays. From investigation, it was discovered that the slide was transitional along the boundary between the granular and clay materials, but became circular in the upper granular material.
Diagram Showing Failure Surfaces along the Christopher Slope