The traditional way of roadside cut slope with “high backfill, the high cut” for mountainous highways definitely seriously damages the original ecological environment and groundwater system, especially to those area with weak ecology, where the damage is almost unrecoverable. It is quite common practice to use artificial vegetation for cut slope virescence, however it still has problems such as low ratio of survivor, high maintenance cost and lack of species diversity. Now people are more and more aware of the importance of ecological environment, it becomes urgent to decrease the damage to ecological environment after ensuring the stability of high slopes.
With the aim to reduce ecological damage, we propose a new design approach which is ecological environment friendly by decreasing cut slope height with steep excavation scheme. The new design is used for a roadside cut slope of provincial trunk highway S223 in Guangdong Province, China. Based on intensive geological investigation and borehole tests, it is found that the slope rock mass is intact and sound, and the rock strength is quite high. Compared with the traditional design scheme with 90.23m high slope, the steep scheme is only 23.46m high. With cable reinforcement, the stability of slope excavated steeply can be guaranteed. Deformation of the slope and the cable force are monitored in details in the period of construction, which show that the deformation of the slope decreases gradually and the final deformation is very small, and the cable tensions change small after the cables were tensioned. It is optimistically estimated that the steep slope should be stable during operation. Comparison analysis between the steep scheme and the common scheme affirms that the steep excavation is better than the traditional scheme in terms of ecological environmental effect, slope height, the excavated amount, the excavated quantity of slope surface, engineering cost. It is concluded that if geological condition permits, the steep cut scheme should be used with better benefits.
