Study and Application for High-Precision on Elevation By a Grab Dredger
Type:
Presented during:
WODCON XX: "The Art of Dredging" - 2013, Brussels, Belgium
Authors:
Cao XB, Chen L, Liu GS
Abstract: Extreme challenges have been posed for achieving high-precision trench excavation associated with the immersed tube tunnel foundation for the Hong Kong-Zhuhai-Macao Bridge project which is now under construction. The trench has a 0.3%-3% longitudinal slope, bottom elevation of -16m to -46m and an allowable depth deviation for excavation of 0-0.5m. Through comparing various kinds of factors including natural conditions (such as water flow, water depth, soil texture, etc.), equipment transformation and dredging-based costs, the Contractor selected the grab dredger which when compared to the trailing suction dredger or the cutter suction dredger, looked far more “modern” for this trench foundation excavation. The Contractor conducted the necessary technological transformation of the 30m3 grab dredger ”Jinxiong” with an excavation depth control featuring a novel concept and reliable performance. Presently, the dredger has been successfully employed on the project. The paper gives a brief description of three steps by which “Jinxiong” has achieve high-precision trench excavation, including a deviation analysis, key points for technological transformation and tests for typical operations of the grab dredger.
Keywords: high-precision excavation, grab dredger, Hong Kong-Zhuhai-Macao Bridge