【文章內(nèi)容簡介】
and below the highly fractured mass. Two main joint sets occur in the rock mass,one set striking parallel to the slope and other perpendicular to dip very steeply .Average joint spacings range from to few joints occur subparallel to the ground surface and these joints are most welldeveloped in the ground surface adjacent to the inclined investigations failed to reveal any significant shear zones or faults oriented in a direction conducive to sliding. The top of the slope is buried beneath colluvial and fan deposits from two creeks which have incised the Fraser Valley slope to from the prominence in which the inclined shaft was prominence is crossed by several linear troughs which trend along the ground surface contours and are evidence of previous downslope movement of the trees growing in these troughs indicate a history of movement of at least several hundred years. The water conduit operated without incident between the initial filling in 1952 and May 1981 when leakage was first noted from the upper access adit located near the intersection of the inclined shaft and the upper leakage stopped when two drain pipes embedded in the concrete backfill beneath the steel lining were plugged at their upsteam holes had been eroded in these drainage pipes where they were not encased in concrtete and it was concluded that this corrosion was responsible for the conclusion appeared to be valid until 25 January, 1989 when a much large water flow occurred. Investigations in the dewatered tunnel revealed a 150 mm wide circumferential tension crack in the steel lining of the upper 55 m from its intersection with the inclined addition, eight pressional bukle zones were found in the upper portion of the inc