Abstract

This paper discusses the geotechnical data collected during investigations as well as results of geological mapping of the an oval shape shaft, 36m long, 11m wide and 31m deep. The results are presented to show how they relate to each other. The authors make an attempt to correlate Qw, RMR and weak rock field assessment for rock mass commonly found in Doha, Qatar.

1. Introduction
1.1 General

The Abu Hamour Southern outfall will form a critical element in the overall storm water drainage net-work for the greater Doha area in the state of Qatar. Construction of Abu Hamour (Musaimeer) Surface & Ground Water Drainage Tunnel – Phase 1 project allows discharge of storm flows from an existing tunnel to sea by collecting storm water runoff from the southern and western parts of Doha, covering a catchment area of approximately 170 km2. The main elements of this project include construction of 9.5 km of 3.7m internal diameter tunnel as well as 21 shafts associated with the tunnel. The shafts on the project are about 30m deep and about 18 shafts will require break out from the shaft and tunnel to forma short adit connection. Launch shaft for two Tunneling Boring Machines TBMs located in the middle of the alignment is shaft AS11 and will need two launch tunnels for erection of two TBMs.

Every engineer coming to the region faces a challenge of adapting to commonly used classification methods in rock mechanics to the rocks of Doha. Since a lot of us depend on previous experience either in the area or in rock of similar type this paper tries to fill the gap providing engineering assessment of the geological information available before the construction when compared to observations made during excavation of shaft AS11 (Figure 1).

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