Tunnelling Market in Finland
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Tunnel 3/2011 ITA/WTC 2011 in Helsinki 19 Tunnelling Market in Finland The following article from the organizing Fin- transport more than 100,000 tation planning with design of nish Tunnelling Association welcomes the parti- passengers per day [2]. the rock structures as one of the The automated metro traf- central tasks. A large amount of cipants at the ITA-AITES World Tunnel Congress fic will go in 2 parallel, 13.9 km geological data was needed to 2011 in Helsinki. It gives an overview over the long rock tunnels (Fig.1). As total, ensure the detailed plans for the most interesting tunnelling projects in Finland. 8 stations will be built in rock. 15 rock structures. The main part of vertical shafts with emergency the surveys was therefore main- exits are designed to serve tech- ly concentrated on rock quality Prof. Pekka Särkkä, Chairman Scientific Committee WTC2011, nical needs as well. The 2 metro investigations. The rock enginee- Helsinki/Finland, www.wtc11.org tunnels will be connected at ring design was mainly focused intervals of 100 to 150 m with on project realisation both in The history of rock engineering destrian precincts, parking and crosscuts for pressure equalisa- terms of time planning as well dates back some 6,000 years. It other facilities to city centres. tion, emergency connections, as of cost planning. has since progressed in a num- Environmental problems and maintenance work. Nine ber of waves, the first of which coupled with a growing aware- access tunnels will be made for 1.3 Rock mechanics design was prehistoric Man’s search ness of them have provided the construction and maintenance. All stations and track switching for shelter from the elements impetus for the fourth wave. The The stations will be approx. 200 halls were set to be modelled and refuge from wild animals minimisation of environment im- m long rock halls with a span of with 3-D rock mechanical ana- in underground caves and ca- pacts, nature conservation, the 23 to 25 m. The project requires lysis tools to simulate the beha- verns. Mines, fortresses, fortified desire to protect old urban envi- the removal of around 1.6 million viour of the rock material and palaces, temples and churches ronments from redevelopment, solid m3 of rock. The tunnels and to quantify the final amount of were all built into the bedrock and stricter legislation have all stations will be excavated with reinforcement needed. All tunnel - some as monoliths hewn from played their part in stimulating the drill-and-blast method and parts and shafts with a challen- a single stone. a revival in underground cons- reinforced with rock bolts and ging design or poor rock quality During the Industrial Revolu- truction. shotcrete. are also modelled in at least 2-D. tion of the nineteenth century, The waves of rock enginee- The results from the rock mecha- society discovered the benefits ring follow and complement one 1.1 Site investigations nical simulations are used, too, of underground construction in another. Infrastructural under- The facilities will be located in to guide building projects in the connection with urbanisation. ground facilities such as metro the hard bedrock composed of vicinity of the metro line. This led to the second wave of systems and various enginee- Precambrian granite and various In Keilaniemi, four 100 m tall rock engineering, when under- ring tunnels and caverns have kinds of gneisses. These contain tower buildings are planned next ground caverns and tunnels not lost their relevance in larger zones with fractured rock, espe- to and above the metro line and were built to improve the com- cities. Similarly, the third wave of cially undersea and in the areas station. The foundation pressu- munity infrastructure, i.e. to ser- relocating recreational and cul- prone to settling, which from re of the buildings is between 2 ve as sewers, metro tunnels and tural facilities is also continuing. tunnelling point of view will be and 4 MPa for each. In these con- municipal engineering facilities. Now, inspired by concern for the challenging. ditions, it is vital to simulate the Military defence structures and natural and urban environment, The engineering geology of interaction between the tunnels power plant technology were the fourth wave is bringing the the area is studied for many years and the surrounding structures also essentially developed. experience of the rock enginee- in several stages. The whole de- in advance, so that the critical The third wave of rock engi- ring field to the fore as a timely sign process was started with the parts of the construction can neering involved the relocation alternative to traditional surface old survey data handed over to be identified and the design can of some human activities from construction [1]. designers, and new, more conci- then be optimised accordingly. the surface to underground ca- se surveys programmed in areas It has to be confirmed that the verns. Sports halls, swimming 1 West Metro extension with wide tunnel spans or critical additional foundation loads on pools, ice hockey rinks, and per- The west metro will be an ex- geological conditions. the surface will not damage the manent art exhibitions exemplify tension of the existing Helsinki tunnels and, on the other hand, the range of the recreational and metro line to the city of Espoo. 1.2 Detail design stage that the tunnels will not cause cultural applications then under- This fully automated line is esti- The decision to begin construc- unacceptable displacements taken. The business community mated to be opened for traffic tion at the end of year 2008 set in on the foundations of the struc- also brought underground pe- at the end of year 2015. It will motion an intensive implemen- tures above. 3-D modelling is 20 Tunnelling Market in Finland Tunnel 3/2011 therefore required to reach the a giant multidimensional rail mechanical analysis are done in platform areas and in escala- precision required, when working tunnel system of Ring Rail Line. using 3DEC-program and criti- tor shafts of the underground with such variable shapes and load The tunnel system consists of 4 cal key blocks are analysed using stations and evaluate the maxi- distributions. underground rail stations with Unwedge-program. mum pressure loads against tun- access tunnels, pressure equali- nel doors and glass structures in 1.4 Excavation design zation and smoke removal shafts, 2.2 Aerodynamic simulation the stations. The excavation design is bon- vertical exit shafts, connection The aerodynamic simulations The station with the high- ded to a beforehand chosen tunnels at 200 m intervals, rail ex- were carried out in 2 steps. The est identified air speeds in the standard profile (Fig. 2, 3). The change areas and heat transfer complete tunnel system was escalator shafts was simulated dimensions for the track tunnel tunnels in portal areas. simulated using 1-dimensional in 3-D to account for the 3-di- are, on the other hand, based transient fluid dynamics code mensional flow effects and high- on space requirements of the 2.1 Rock mechanical IDA Tunnel. The code solves light the areas with the highest metro train and its rail system simulation the aerodynamic flows occur- velocities. The air flows from/to plus an additional 1200 mm for Rock mechanical analysis is ring in the tunnel network due the adjacent tunnel sections ob- an emergency exit lane. In the needed to predict structural train motion and thermal or tained from 1-dimensional simu- parts where the tunnels cross the behaviour of rock mass and to external influences governing lations were used as boundary sea, free space to build a water- determine right location and po- incompressible fluid flow equa- conditions for the 3-D studies. pressure-proofed construction is sition and needed reinforcement tions in 1-D. The 3-dimensional The 3-D simulations were carried reserved in the excavation pro- procedures of underground faci- effects of the flow are modelled out using the commercial CFD file. Furthermore, a large amount lity. In Ring Rail Line all 4 under- using pressure loss coefficients software package ANSYS CFX. of grouting and reinforcement ground stations are simulated and friction factors as in nor- Simulations in the early phase profiles for a wide range of dif- using interpreted geometrical mal practise for transient 1-di- showed that the highest air ferent geological conditions are and mechanical model of rock mensional pipe flow networks. speeds are found at Ruskeasan- needed in addition to the exca- mass. Rock mechanical simula- Different tunnel system layouts ta station (Fig. 5) and therefore vation profiles. tions showed the critical areas and changed tunnel profiles it was chosen to be modelled in which need extra reinforcement have been investigated in 1-D 3-D. As well as highest observed 2 Ring Rail Line procedures and stability super- with various train timetables to speeds in escalator shafts, Ruske- The Ring Rail Line is an important vision during construction. Rock determine the peak air speeds asanta station has the disadvan- circular rail route of the Helsinki West metro line Metropolitan Area. It is an urban two-track passenger line for lo- cal traffic in Vantaa between Vantaankoski and Tikkurila and a rail link from Helsinki to Hel- sinki-Vantaa airport (Fig. 4). The total length of the new line is 18 km, of which 8 km run in twin tunnels mainly under the Helsin- ki-Vantaa airport area. New SM5 low-floor trains will operate on the Ring rail Line at 10-minute intervals in both directions du- ring peak periods. The maximum train speed will be 120 km/h. Construction of the Ring Rail Line began in spring 2009 by tunnel excavations using drill and blast method.