Construction Technology of Deep Foundation Pit Under Rock-Soil Combinational Geological Condition

Considering the situation of straitness field and approximately vertically excavation,pile-anchor protection technique is applied in the upper sand layer of ultra-deep foundation pit,the shotcrete and rock bolt technique is employed in the bottom bedrock layer.In the slope of soil-rock combine surface,the anchor plate wall is set up to strengthen the inlay firm of support pile foot.According to the technical safe parameters which are observed from field testing explosion,the combination of divide layers of milliseconds elementary difference delay explosion technique and the static broken technique are employed to release the exploding vibration.Engineering practice indicates that the present construction method is able to effectively protect foundation pit support system.