The development of the ngi q system for rock mass classification began in the early 1970s, and was. Rock mass classification 5 deeres rqd was widely used, particularly in north america, after its introduction. By using a different vlan tag for each customer we can separate the. As shown in figure 2, the qsystem is a design method based on the tunnelling quality index, q. 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 qsystem was developed 40 years ago for describing rock mass. The development of the ngi qsystem for rock mass classification began in the early 1970s, and was. Pdf a thorough treatment of the case records used to develop the. Scan planning and logistics are managed by arora and associates, p. Experience from tunnel projects in norway has shown that if the magnitude of the major principal stress approaches about 15 of the compressive strength.
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. 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. Traditionally, tunnel supports have been classified into two groups, temporary and permanent. 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. 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. Gecko geotechnics has developed a mobile phone application for empirically design ground support for tunnels and underground excavations using the qsystem. The tunnelling index q was developed by the norwegian geotechnical institute in the 1970s barton et al. 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. The application of the qtunnelling quality index to rock mass assessment at impala platinum mine by w. A supersonic, a hypersonic and a ballistic windtunnel are also part of the early aeronautical research history at kth. The shear strength parameters and geomechanical properties of the rock masses at each borehole location were obtained by using the geological strength index. Approaches to the design of tunnels presents international design procedures or tunnels. The basic functions of a tunnel support system are to keep the tunnel stable and to make the opening usable.
Introduction at its most basic, a tunnel is a tube hollowed through soil or stone. Barton, lien and lundeengineering classification of rock masses for the design of tunnel support. Recently, rock mass classification using both rmr and qsystem has been frequently used for tunnel design together with numerical analysis, in korea. Design and evaluation of a lowspeed windtunnel with. Rock mass characterization for underground hard rock mines.
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. 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. Gecko geotechnics has developed a mobile phone application for empirically design ground support for tunnels and underground excavations using the q system. In reality the qsystem is far more than six parameters, as.
Engineering classification of rock masses for the design of tunnel support. Bieniawski design enterprises, prescott, arizona, usa abstract. 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. It expresses rock quality, q, as a function of 6 independent parameters. In 1993 the system was updated to include more than cases grimstad and barton, 1993.
This report discusses tunnel design procedures based on various rock mass classification systems. Together with the estimating ratio between the span or wall height of the opening and the stability requirements to the use of the tunnel or. However, use of sprayed concrete has been extended in rock masses of good quality. In case of the aeronautical lswts, the requirements of those parameters are extremely strict, often substantially increasing the cost of facilities. The 1993 updated version of the q system tunnel support diagram grimstad and barton 1993, which is reproduced in fig. Case study comparing from qsystem and terzaghis rock. Comparison among different criteria of rmr and qsystem for. 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. It also allows for emailing of automatically generated reports. 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. A good starting point is essential to the process and facilitates safe and economic design. The impact of earthquakes on tunnels in different rock mass. 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. For mining applications, the qsystem recommendation is for an esr of 3 to 5 for.
A comparison is made between the tunnel support design based on the. As shown in figure 2, the q system is a design method based on the tunnelling quality index, q. In 1681 gunpowder was first used for blasting the tunnels. The actual density of rock bolting which proved necessary to install, following. Tunnel design criteria common design guidelines 2015 c26. 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.
The application of the qtunnelling quality index to rock. 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 process of design of a tunnel support system to resist ground loading. Nchrp project 2068a scan 0905 best practices for roadway. 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. 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. Ground improvement ahead of tbm via a pilot tunnel using fiberglass anchors and tam grouting 3. 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.
Therefore, the general approach to the design o tunnels includes site. Ngi has developed a q system app and a users guide that can be downloaded free of charge. Recently, rock mass classification using both rmr and q system has been frequently used for tunnel design together with numerical analysis, in korea. 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. Q systemsystem the q system of rock mass classification was developed in 1974 in norway by prof. The initial primary support, comprising rockbolts and mesh, was designed using the q system 17. The qsystem is also used for mapping rockmass conditions during tunnel and cavern construction to aid in the choice of permanent support. The qsystem is a classification system for rock masses with respect to stability of underground openings. Critical assessment of rmr based tunnel design practices. Ground classification systems in tunnel construction. 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 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.
This is an unscheduled inspection to assess structural damage resulting from environmental factors or human actions. 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. The q system is developed as an empirical design method for rock support. Computer based finite element analysis fem has given yet another dimension to design approach. Qsystemsystem the qsystem of rock mass classification was developed in 1974 in norway by prof. Methodology for tunnel and portal support design in mixed. Together with the estimating ratio between the span or wall height of the opening and. A total of 176 case histories by potvin and by nickson16 of unsupported open stopes are plotted on the. Bhasin, johansen, barton and makuratrock joint sealing experiments using an ultra fine cement grout. Ngi has developed a qsystem app and a users guide that can be downloaded free of charge. Demolition plans, plans showing new and existing utilities, utility and tunnel details, an outline specification, and developed tunnel plans and profiles.
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. Design, construction, maintenance, inspection, and operations, whose members are listed below. 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 numerical value of the index q varies on a logarithmic scale. The tunnel grounds were classified according to the qsystem, rmr method and natm. The final estimates of permanent support were found to compare well with the preliminary estimates. Bartonsome new qvalue correlations to assist in site characterization and tunnel design. The 1993 updated version of the qsystem tunnel support diagram grimstad and barton 1993, which is reproduced in fig. Tunnels, and shafts in rock, engineer manual em 111022901, washington. The writers have noted the frequent use of the qsystem in various roles in mining.
The rock load estimated from the qsystem empirical method was based on the qvalue and the. Comparison among different criteria of rmr and qsystem. The qsystem for rock mass classification, developed at the norwegian geotechnical institute ngi in 1974, originally included a little more than 200 tunnel case. The qsystem is developed as an empirical design method for rock support.
Some years afterwards, application in norwegian road tunnels followed. It appears that the rock tunnelling quality q can now be considered to be a function of. The qsystem for rock mass classification is developed by barton, lien, and lunde. 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. It expresses the quality of the rock mass in the socalled qvalue, on which are based design and support recommendations for underground excavations. These classification systems are described and guidelines are given for stepbystep. Tunnel support design by comparison of empirical and.
A tunnel characterized by advanced or unique structural elements or functional systems. An empirical approach for tunnel support design through q. 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. First time the ventilation system for tunnel was developed in 1927 in holland tunnel. The specific purposes of support systems, however, depend greatly on the purposes of the tunnel. In a subsequent site visit the qsystem was applied insitu. The q system is also used for mapping rockmass conditions during tunnel and cavern construction to aid in the choice of permanent support. 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. All the tunnels were in hawkesbury sandstone, with depths of cover ranging from about 20m to about 80m. 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. Barton and abrahaoemploying the qtbm prognosis model. 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. In addition to the visual observation, hammering with a scaling rod or a hammer will give. The q system is empirical with regards to rock support.
It has a 3 m long test section of 2 2 m2 cross section and a maximum speed of 62 ms. Design and evaluation of a windtunnel with expanding corners 3 l2000, was built in 1963 and is still used for aeronautical research. In most tunnelling projects, the ground actively participates in providing stability to the opening. Advantages and difficulties when applied to a tunnel project will be highlighted. Underground excavation design classification alfred zettler rock tunnelling quality index, q the system was proposed by barton et al. 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 of rock mass classification was developed in norway in. Design methodology for a quick and lowcost wind tunnel.
Empirical tunnel support types and categories were selected for each of the three classification systems. The design of stable stope spans for shallow mining operations. Finally, an approach to determine the new seismic support system using. It is important to combine application of the q system with deformation measurements and numerical simulations in squeezing rock or very weak rock.
Rqd rock quality designation jn is based on the number of joint sets jr is based on discontinuity roughness ja is based on. We develop designs in accordance with both prescriptive and performancebased regulations and standards. 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. The diagram below shows the relationship between these underground structures in a typical mountain tunnel. In a subsequent site visit the q system was applied insitu. Combining the rmr, q, and rmi classification systems. Nchrp project 20 68a is guided by a technical project panel and managed. Tunnel support measures are selected based on rmr and q classification systems. Case study comparing from qsystem and terzaghis rock load. The initial primary support, comprising rockbolts and mesh, was designed using the qsystem 17. Abstract the design of support for tunnels in weak rock is an iterative process.
The impact of earthquakes on tunnels in different rock. 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. A twodimensional approach for designing tunnel support in weak rock john h. The qsystem can therefore be used as a guideline in rock support design decisions. In the context of this discussion, the most important use of rqd is as a component of the rmr and q.