Breadth and Depth – Ground Breaking Shafts for Melbourne Sewer Projects

摘要

Recent major urban trunk sewer infrastructure projects in Melbourne have involved constructionrnof nearly 10 km of tunnel boring machine (TBM) driven tunnels in a range of geological conditionsrnvarying from soft alluvial soils to hard volcanic rock. To provide both construction and permanentrnaccess to the new trunk sewer network, a total of 17 shafts between 5 m and 13 m in diameter, andrnup to 64 m in depth have been constructed. This paper describes the design and construction of therntemporary shaft support systems for the shafts.rnThe range and variability of geological conditions at each shaft site required the adoption of thernfollowing shaft support systems across the projects – jet grouting, sheet piles, diaphragm wall, secantrnpile, contiguous pile, reinforced shotcrete rings and rock bolts.rnGroundwater control, settlement, TBM launch and reception chambers at the shaft base, chambersrnand TBM launches at mid-depth of shafts, connection shafts between new and existing sewers andrnbypass pumping shafts are among the challenges that have been met.rnThis paper reports on the some of the challenges involved and experience gained in developingrndesign and construction solutions for large diameter shafts that are excavated within varying geologyrnin Melbourne over the past three years.