Methodology for tunnel and portal support design in mixed. The initial primary support, comprising rockbolts and mesh, was designed using the qsystem 17. The numerical value of the index q varies on a logarithmic scale. Tunnels, and shafts in rock, engineer manual em 111022901, washington. Handley synopsis publications on hard rock tunnel support design in the south african mining industry have originated primarily from the gold mines during the past 50 years. The rock load estimated from the qsystem empirical method was based on the qvalue and the. Advantages and difficulties when applied to a tunnel project will be highlighted. The basic functions of a tunnel support system are to keep the tunnel stable and to make the opening usable. The 1993 updated version of the qsystem tunnel support diagram grimstad and barton 1993, which is reproduced in fig. Bartonsome new qvalue correlations to assist in site characterization and tunnel design. It also allows for emailing of automatically generated reports.
The final estimates of permanent support were found to compare well with the preliminary estimates. Cording and deere 1972, merritt 1972 and deere and deere 1988 attempted to relate rqd to terzaghis rock load factors and to rockbolt requirements in tunnels. Permanent support recommendations based on q values and spanesrthe first version of the system was published in 1974, and through the years the system has been updated many times to include new and improved tunnel support technology. Bhasin, johansen, barton and makuratrock joint sealing experiments using an ultra fine cement grout. Gecko geotechnics has developed a mobile phone application for empirically design ground support for tunnels and underground excavations using the q system. Some years afterwards, application in norwegian road tunnels followed. Nchrp project 20 68a is guided by a technical project panel and managed. The 1993 updated version of the q system tunnel support diagram grimstad and barton 1993, which is reproduced in fig. Ground classification systems in tunnel construction. Nchrp project 2068a scan 0905 best practices for roadway. According to the most widely adopted procedure in korea, rock mass is allocated into any of 5 classes from classi very good to classv very poor, based on the results either from one of the. In the context of this discussion, the most important use of rqd is as a component of the rmr and q. Therefore, the general approach to the design o tunnels includes site. For professional tunnel engineers, for whom money and time are in short supply particularly in early stages of a project, this paper critically assesses what works best with the rmr system, today 40 years after its development and extensive accumulated experience.
In case of the aeronautical lswts, the requirements of those parameters are extremely strict, often substantially increasing the cost of facilities. Rqd rock quality designation jn is based on the number of joint sets jr is based on discontinuity roughness ja is based on. The q system is also used for mapping rockmass conditions during tunnel and cavern construction to aid in the choice of permanent support. All the tunnels were in hawkesbury sandstone, with depths of cover ranging from about 20m to about 80m. The qsystem for rock mass classification, developed at the norwegian geotechnical institute ngi in 1974, originally included a little more than 200 tunnel case histories, mainly from scandinavia barton et al. Therefore, the design aim of a wind tunnel, in general, is to get a controlled flow in the test chamber, achieving the necessary flow performance and quality parameters. This is an unscheduled inspection to assess structural damage resulting from environmental factors or human actions. Design and evaluation of a lowspeed windtunnel with. Together with the estimating ratio between the span or wall height of the opening and.
Tunnel design criteria common design guidelines 2015 c26. The qsystem can therefore be used as a guideline in rock support design decisions. Tunnel support design by comparison of empirical and. Critical assessment of rmr based tunnel design practices. Rock mass classification 5 deeres rqd was widely used, particularly in north america, after its introduction. A tunnel characterized by advanced or unique structural elements or functional systems. Finally, an approach to determine the new seismic support system using. In 1993 the system was updated to include more than cases grimstad and barton, 1993. The tunnel grounds were classified according to the qsystem, rmr method and natm.
Case study comparing from qsystem and terzaghis rock. Design, construction, maintenance, inspection, and operations, whose members are listed below. Computer based finite element analysis fem has given yet another dimension to design approach. A comparison is made between the tunnel support design based on the classical terzaghi rock load method and the support selection based on the rsr concept, the geomechanics classification, and the q system. Approaches to the design of tunnels presents international design procedures or tunnels. A twodimensional approach for designing tunnel support in weak rock john h. The application of the qtunnelling quality index to rock. In comparing the q system and rmi for preliminary tunnel support design in the case of high insitu stresses, the q system has a stress reduction. The qsystem is also used for mapping rockmass conditions during tunnel and cavern construction to aid in the choice of permanent support. The q system is developed as an empirical design method for rock support. Scan planning and logistics are managed by arora and associates, p. Barton and abrahaoemploying the qtbm prognosis model. The design of stable stope spans for shallow mining operations b joint orientation adjustment factor and c gravity adjustment factor to determine the modified stability number, n, which is used in the modified stability graph method6, 15 for dimensioning of open stopes in mining. A supersonic, a hypersonic and a ballistic windtunnel are also part of the early aeronautical research history at kth.
It expresses rock quality, q, as a function of 6 independent parameters. It appears that the rock tunnelling quality q can now be considered to be a function of. The writers have noted the frequent use of the qsystem in various roles in mining. In a subsequent site visit the q system was applied insitu. Recently, rock mass classification using both rmr and qsystem has been frequently used for tunnel design together with numerical analysis, in korea. It should be noted that the application of these systems at the design stage is strongly dependant on the quality of the site investigation data available. The diagram below shows the relationship between these underground structures in a typical mountain tunnel. A good starting point is essential to the process and facilitates safe and economic design. Ground improvement ahead of tbm via a pilot tunnel using fiberglass anchors and tam grouting 3. Recently, rock mass classification using both rmr and q system has been frequently used for tunnel design together with numerical analysis, in korea. Qsystemsystem the qsystem of rock mass classification was developed in 1974 in norway by prof. The tunnel ground is classified and divided by the empisical classification systems like rock mass rating rmr, q system q, and geological strength index gsi. It is important to combine application of the q system with deformation measurements and numerical simulations in squeezing rock or very weak rock.
In a subsequent site visit the qsystem was applied insitu. Demolition plans, plans showing new and existing utilities, utility and tunnel details, an outline specification, and developed tunnel plans and profiles. The qsystem for rock mass classification is developed by barton, lien, and lunde. Underground excavation design classification alfred zettler rock tunnelling quality index, q the system was proposed by barton et al. Barton, lien and lundeengineering classification of rock masses for the design of tunnel support. Ngi has developed a q system app and a users guide that can be downloaded free of charge. For mining applications, the qsystem recommendation is for an esr of 3 to 5 for.
In reality the qsystem is far more than six parameters, as. An empirical approach for tunnel support design through q. The qsystem for rock mass classification, developed at the norwegian geotechnical institute ngi in 1974, originally included a little more than 200 tunnel case. Case study comparing from qsystem and terzaghis rock load. Core logs, seismic profiles and surface mapping were used as a basis for preliminary design of permanent support for the 9 meters span tailrace tunnel, again using the qsystem. Empirical tunnel support types and categories were selected for each of the three classification systems. Design methodology for a quick and lowcost wind tunnel. Rock mass characterization for underground hard rock mines. The qsystem is a classification system for rock masses with respect to stability of underground openings. The process of design of a tunnel support system to resist ground loading. Pdf a thorough treatment of the case records used to develop the. Jan 26, 2017 the largest tunnel in ancient times was a 4,800foot long, 25footwide, 30foothigh road tunnel the pausilippo between naples and pozzuoli, executed in 36 b. Tunnel systems our tunnel experts plan, design, assess and support the operations and systems of tunnels metro, road, rail, water, utility throughout the full project life cycle. Experience from tunnel projects in norway has shown that if the magnitude of the major principal stress approaches about 15 of the compressive strength.
Abstract the design of support for tunnels in weak rock is an iterative process. The design of stable stope spans for shallow mining operations. In most tunnelling projects, the ground actively participates in providing stability to the opening. The specific purposes of support systems, however, depend greatly on the purposes of the tunnel. Traditionally, tunnel supports have been classified into two groups, temporary and permanent. Comparison among different criteria of rmr and qsystem.
This means that it is crucial to define the safety concept as early as in the initial design phases, and to obtain the consent of all involved parties. We develop designs in accordance with both prescriptive and performancebased regulations and standards. Ngi has developed a qsystem app and a users guide that can be downloaded free of charge. Comparison among different criteria of rmr and qsystem for. The shear strength parameters and geomechanical properties of the rock masses at each borehole location were obtained by using the geological strength index. It has a 3 m long test section of 2 2 m2 cross section and a maximum speed of 62 ms. First time the ventilation system for tunnel was developed in 1927 in holland tunnel.
Gecko geotechnics has developed a mobile phone application for empirically design ground support for tunnels and underground excavations using the qsystem. The q system is empirical with regards to rock support. The rock load estimated from the terzaghis rock load classification method was obtained by correlating site tunnel convergence monitoring of a mined tunnel with a back analysis of a 3d numerical model of the mined tunnel. It expresses the quality of the rock mass in the socalled qvalue, on which are based design and support recommendations for underground excavations. By using a different vlan tag for each customer we can separate the.
Calculation methods for tunnel design draft programme the objective of this training session is to present the design methods commonly used to assess tunnel stability. Design and evaluation of a windtunnel with expanding corners 3 l2000, was built in 1963 and is still used for aeronautical research. The largest tunnel in ancient times was a 4,800foot long, 25footwide, 30foothigh road tunnel the pausilippo between naples and pozzuoli, executed in 36 b. The application of the qtunnelling quality index to rock mass assessment at impala platinum mine by w. However, use of sprayed concrete has been extended in rock masses of good quality. Tunnel support measures are selected based on rmr and q classification systems. Permanent support recommendations based on qvalues and spanesrthe first version of the system was published in 1974, and through the years the system has been updated many times to include new and improved tunnel support technology.
As shown in figure 2, the q system is a design method based on the tunnelling quality index, q. These include the use of q or n for openstope behaviour prediction, qsystem support and reinforcement guidelines for permanent mine roadways, and qvalue based geotechnical zoning for. A comparison is made between the tunnel support design based on the. The tunnelling index q was developed by the norwegian geotechnical institute in the 1970s barton et al.
As shown in figure 2, the qsystem is a design method based on the tunnelling quality index, q. The initial primary support, comprising rockbolts and mesh, was designed using the q system 17. A total of 176 case histories by potvin and by nickson16 of unsupported open stopes are plotted on the. A where q volumetric flow rate, ft3min v air velocity, ftmin or fpm a cross sectional area, ft2 or sf 1 velocity 50 fpm air flow hood 2 velocity 3000 fpm duct flow rate at point 1 is called q 1 and is equal to flow rate at point 2 which is called q 2. Bieniawski design enterprises, prescott, arizona, usa abstract.
The qsystem was developed 40 years ago for describing rock mass. Examples include 25 m2 and 162 m2 headrace tunnels and an underground sewage treatment plant constructed in 1 km of caverns, 16 m in span. The earliest reference to the use of rock mass classification for the design of tunnel support is in a paper by terzaghi 1946 in which the rock loads, carried by steel sets, are estimated on the basis of a descriptive classification. Q systemsystem the q system of rock mass classification was developed in 1974 in norway by prof. Ground classification systems in tunnel construction trl.
These classification systems are described and guidelines are given for stepbystep. These include the use of q or n for openstope behaviour prediction, qsystem support and reinforcement guidelines for permanent mine roadways, and qvalue based geotechnical zoning for future or present mining resources. Engineering classification of rock masses for the design of tunnel support. The development of the ngi q system for rock mass classification began in the early 1970s, and was. In 1681 gunpowder was first used for blasting the tunnels. The qsystem is developed as an empirical design method for rock support. The qsystem of rock mass classification was developed in norway in. Combining the rmr, q, and rmi classification systems. The system was proposed on the b i f l i f 212 t l basis of an analysis of 212 tunnel case hi t i histories f sii df rom scandinavia.
The impact of earthquakes on tunnels in different rock mass. The actual density of rock bolting which proved necessary to install, following. Introduction at its most basic, a tunnel is a tube hollowed through soil or stone. The development of the ngi qsystem for rock mass classification began in the early 1970s, and was. The q system for rock mass classification, developed at the norwegian geotechnical institute ngi in 1974, originally included a little more than 200 tunnel case histories, mainly from scandinavia barton et al. The impact of earthquakes on tunnels in different rock. Increase of cohesionahead of tunnel face face improvement using grouting control of preconvergence by face pretreatment athens metro numerical analysis in the design of urban tunnels lecture outline 1. Core logs, seismic profiles and surface mapping were used as a basis for preliminary design of permanent support for the 9 meters span tailrace tunnel, again using the q system. This report discusses tunnel design procedures based on various rock mass classification systems. A comparison is made between the tunnel support design based on the classical teraghi rcak load method and the support selection based on the rsr concept, the geomechanic classification. It is hoped that the information herein, based on experiences rom a wide range o tunneuing projects, will be disseminated to tunnel designers throughout the world.
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