| Autor: |
Peterfreund, S., Goudelis, D., Jovanovic, B. |
| Předmět: |
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| Zdroj: |
EA National Conference Publications; 2023, p348-358, 11p |
| Abstrakt: |
Watercare's Central Interceptor project in Tāmaki Makaurau (Auckland) involves the construction of a new pump station adjacent to Māngere Wastewater Treatment Plant as well as a 14.7km tunnel and two branch sewers. The Māngere Pump Station (MPS) has two shafts: one large 50 m deep shaft to house the wet well and pump station, and an adjacent smaller inlet shaft. To assemble and launch the tunnel boring machine (TBM) for the first 7.5 km drive, an extended launch area was preferable. Rather than construct a rectangular launch and pump station shaft requiring ground anchors or strutting, a dual-cell (peanut-shaped) shaft design was developed using two adjacent circular shafts acting in hoop compression with a shared wall. Although the original design allowed for excavation of the diaphragm wall panels using a grab, the contractor elected to use a hydromill. This is understood to be the deepest application of a diaphragm wall shaft in New Zealand to date, and the first use of this dual-cell arrangement in Australasia. This paper discusses the unique design challenges encountered at the MPS shaft. These included Y-shaped panels at the intersection of the two cells; a window through the centre wall to accommodate the TBM launch and permanent connection between the inlet shaft and wet well; and allowing for load-sharing in the permanent condition between the diaphragm walls and the cast-in-situ lining. Construction of the diaphragm wall overcame anticipated and unexpected challenges as well. Construction began in late 2019 but was disrupted by the COVID-19 pandemic. One consequence of the COVID-19 lockdown was overstrength primary panel concrete and the additional cutting effort required by the hydromill. Other construction issues discussed include reinforcing cage installation and tremie placement for the multi-bite panels; slurry desanding operations; and additional quality control and assurance measures to certify the concrete panels as a permanent structure. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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