Parking facility P-Hamppi under central Tam pare has now been in use for few years. During completion, it was the first large span cavern in Tampers city centre with a span of 32 m and a volume for 972 cars. Due to the demanding conditions i.e. large cavern close to the ground surface above lively city centre and fractured rock the project included an in-situ stress measurement campaign and rock mechanics stability studies, e.g. 2D and 3D numerical analyses and rock monitoring during construction. Rock stresses play often an important role in the rock engineering projects in Finland in the underground facilities near the rock surface. Horizontal stresses can be utilized in stabilizing rock caverns and may then allow wide caverns to be excavated. Hence the stress measurements were also conducted in the P-Hamppi project with hydraulic fracturing method. This paper describes how the results were analysed, utilized in the stability analyses and compared with the behaviour predicted by modelling and the observed behaviour.
The city of Tampere which is the third largest city in Finland is located on a cliff rise, and Tampere's main street Hameenkatu follows its highest ridge. Because of this, the opportunities for building underground in Tampere are outstanding. Growing city of Tampere had started to place more emphasis on the issues of pedestrians and on light and public transport. The planning of a parking facility underground served this development. The developer of the P-Hamppi is Finn park Ltd, which is a Tampere-based parking services developer and operator owned by the City of Tampere.
P-Hamppi with a length of 650 m is located at the depth of around 30 m under the main street Hameenkatu and between the Tammerkoski rapids and the railway station (Figure 1). The span of the P-Hamppi is 32 m, the height is 10m and its excavated rock volume was around 210 000 m3 and the capacity for 972 cars (Figure 2). Planning of the facility started in the end of 2007, the rock construction took place in 2009–2011 and the first cars drove into P-Hamppi in November 2012. P-Hamppi received EPA Award 2013 to be the best new parking facility in Europe.