Detail of JTG D70-2004

Introduction of JTG D70-2004

1 General provision 1.0.1 This code is formulated with a view to provide technical criteria for design of mountain ridge road tunnel. 1.0.2 This code is applicable to all kinds of two-lane tunnels with major excavation mean of drilling and blasting method, road tunnel of other forms may also comply with this. 1.0.3 Tunnel layout and design shall abide by first principles of give full play to tunnel function, safety and economically construct tunnel. Design of the tunnel shall have a complete investigation and survey information; it shall takes topography, geology, hydrology, meteorology, earthquake, trafficking and its components, as well as the construction and operation conditions into consideration, and then makes multivariate comparison on technology, economy, and environmental protection to make the design of the tunnel meet the requirement of safe and practical, reliable quality, reasonable economy and state-of-art technology. 1.0.4 Road tunnel may be divided into four types according to its length, see table 1.0.4. Table 1.0.4 Classification of the Road Tunnel Length Classification Special long tunnel Long tunnel Middle tunnel Short tunnel Length (m) L>3000 3000≥L>1000 1000≥L>500 L≤500 Note: Length of the tunnel refers to distance between intersecting line of portal wall face and pavement at both ends and intersecting point of the channel center line. 1.0.5 Main structure of the tunnel must be designed as permanent building: with provided strength, stability and durability; established tunnel shall be able to adapt to the needs of long-term operation to facilitate maintenance operations. 1.0.6 It shall strengthen coordination between design of the major structures like tunnel support lining, drainage-proof, roads and design of operating facilities like ventilation, lighting, power supply/distribution, fire, and traffic control operation to a rational comprehensive design. If necessary, it shall carry out special design and studies to deal with relevant technical issues. 1.0.7 Civil design of the tunnel shall reflect the concept of dynamic design and informatization construction and be established general program on geological observations and monitor measurements; tunnels with complicated geological conditions shall be established geological prediction program to timely judge reasonableness for the design, and to adjust support parameters and construction program. By dynamic design, it makes supporting structure adaptable to the actual situation in the surrounding rock, and makes it with greater security and more economy. 1.0.8 Design of the tunnel shall implement relevant technical economy policies of the nation; positively and prudently adopt new techniques, new materials, new equipments and new technology. 1.0.9 Design of the tunnel must meet the requirement of state regulations like state land management, environmental protection, water and soil conservation. It shall pay attention to the economic use of land, farmland protection and water conservancy facilities, to protect the existing vegetation as possible and properly handle the waste slag and sewage. 1.0.10 Not only the requirements for design of road tunnel, but also those specified in the current relevant compulsory ones of the nation shall be complied with. 2 Major terms and symbols 2.1 Terms 2.1.1 Road Tunnel Tunnel for car and pedestrian traffic is divided into two kinds generally: special for automobile and mixed tunnel for both automobiles and pedestrians. 2.1.2 Mountain tunnel It refers to the tunnels running through hills or mountains. It is relative to the city tunnel and immersed tunnel and denotes different names of the built locations. 2.1.3 Rock quality designation (RQD) It refers to drill length percentage accumulated by cores with length of above 10cm. 2.1.4 Rock mass classification Divide the rock mass into some grades with different degree of stability with the object of civil engineering. 2.1.5 Environmental survey Inquiry on environmental impact of the channel surroundings as a result of the construction of the tunnel 2.1.6 Hydrological survey Inquiry on surface water and groundwater influencing the tunnel engineering and its surrounding environment 2.1.7 Geological survey Inquiry made in order to understand distribution of the rock mass or strata, formation time, degree of weathering or geological structure. 2.1.8 Water inflow into tunnel Groundwater inflow into the tunnel from surrounding rocks around the tunnel and along with the tunnel excavation 2.1.9 Load It refers to strength acting on structures and generating stress on the structure. 2.1.10 Surrounding rock pressure After tunnel excavation, pressure acting on rock mass or support structure around the grotto because of deformation or loosening of the surrounding rock. 2.1.11 Unsymmetrical pressure Condition of pressure acting on tunnel is left-right asymmetry with one side pressure is outsize; unsymmetrical load acting on tunnel structure. 2.1.12 Loosening pressure It refers to reasons like blasting of the tunnel excavation, support sinking liner and interstice behind the lining that cause loosening of surrounding rock around the tunnel. It is equivalent to gravity of surrounding rock in a certain height and it is soil pressure as a direct load on the tunnel support and lining. 2.1.13 New Austrian Tunneling Method (NATM) NATM is a kind of method and principle supervising tunnel and underground engineering design/construction through measurement and monitoring of surrounding rock and support. It is applied for rock mass mechanical theory and with basic point of maintaining and utilizing self-supporting property of surrounding rock. Adopting bolt and sprayed concrete as major support mean, it timely support and control the deformation and relaxation of the surrounding rock, which makes the surrounding rock form a constituent of the support system. 2.1.14 Inner section It refers to cross-sectional area and shape inside the tunnel lining 2.1.15 Portal It is a tunnel structure set with a view to retain soil and protect slope, lies in the tunnel adit; it lies in the tunnel adit. 2.1.16 Lining Struct covered by surrounding rock around the tunnel with a view to control and prevent the deformation or slumping of the surrounding rock, and ensure the stability of the surrounding rock, or to deal with the gushing water and leaking water, or for the purpose of tidiness or esthetic appearance for the inner tunnel. 2.1.17 Invert Reverse arch structure set at bottom of the tunnel in order to improve the stressing condition of support structure on top of the tunnel. 2.1.18 Neighborhood tunnel It refers to tunnel structure with small clear distance between the up and down line of the double-tunnel walls, and it cannot be regarded independently as double-tunnel. 2.1.19 Multi-arch tunnel It refers to tunnel structures of arch-part lining structure of the double-tunnel connected by central cylinder. 2.1.20 Vertical shaft Sap set vertically to improve operating ventilation or construction conditions 2.1.21 Incline or inclined shaft Sap set with a certain inclination to improve operating ventilation or construction conditions. 2.1.22 Horizontal adit Sap set approaching horizontal operation of the more-in material and slag tap when making construction by dividing the tunnel into several work areas. Horizontal adit may also be used for operating ventilation. 2.1.23 Advancing drift As a result of the large tunnel section or complex surrounding rock conditions, and with difficult full section method during the excavation process, it advancing excavate a light-sectional tunnel in the excavated section of the tunnel and this light-sectional tunnel is called advancing drift. 2.1.24 Ventilation A kind of air change behaviors exhausting out the noxious gas in the tunnel. 2.1.25 Lighting By setting the tunnel lighting, to achieve the required brightness for the traffic safety 2.2 Symbols BQ——Basic quality index of the rock mass; [BQ]——Corrected value for the basic quality index of the rock mass; Rc——Saturated compressive strength of single axle of the rock; Ra——Compressive strength of concrete or bricking-up; RJ——Ultimate strength of tensile of the concrete; IS (50)——Measured strength index of rock point loading; K1——Correction factor influencing the groundwater; K2——Correction factor influencing attitude of the main weak structural plane; K3——Correction factor influencing the primary stress state; Kv——Coefficient of integrity of the rock mass; Jv——Cleavage number of the rock mass volume; Sn——Number of per measuring line on the nth group of cleavage; Sk——Numbers of non-grouping cleavage on each cubic meter rock mass; vpm——Velocity of elastic longitudinal wave of rock mass; vpr——Velocity of elastic longitudinal wave of rock; бmax——Maximal primary stress along the axial direction of the vertical tunnel; γ——Density of the surrounding rock; k——Elastic resistance coefficient; E——Modulus of deformation; μ——Poisson ratio; φ——Calculated frictional angle; B——Sectional width of tunnel excavation; W——Driveway width; LL——Width of the left side; LR——Width of light side; L——Lateral width; C——Surplus width; J——Width of the repairing way; h——Height of the repairing way or sideway; R——Width of the sideway; H——Height of building line of the tunnel; K——Elastic resistance coefficient of the surrounding rock; δ——Displacement value of the lining; n——Slope ration of the excavation; m——Slope ration of the back fill dam side 3 Tunnel investigation and surrounding rock classification 3.1 General requirements 3.1.1 It shall determine content and scope of the gathered and surveyed data according to the mission, objectives and requirements of different phases and aiming at roads grades, the characteristics and the scale of the tunnel, and seriously to carry out a investigation, mapping, exploration and test. Investigated information shall be complete, accurate and meet the design requirements. 3.1.2 Investigation shall include two phases: investigation before construction and investigation under construction. The investigation, scope, accuracy and so on in the pre-construction phases shall be in line with the requirements of the corresponding phases of the design; investigation during the construction shall be conducted in a timely manner, and it shall forecast and solve geological problems encountered in the construction in order to provide criteria for verifying or modifying the design and construction. 3.1.3 It shall compile corresponding survey planning according to topography and geological conditions of region passing by the tunnel, and it shall comprehensively consider phases, methods and scope of the investigation. During the investigation process, if discrepancy was found between the actual geological conditions and the situation not expected, it shall amended the survey planning in a timely manner. 3.1.4 Surrounding rock classification shall be judged by adjoin method of both qualitative and quantitative classification. 3.2 Collection of data 3.2.1 It shall completely gather the following available information in tunnel areas: 1 Topography, maps and remote sensing and telemetry data; 2 Information about engineering geology, hydrogeology (especially the type, nature, scale and extent of injury of the natural geological disasters), and it shall also analyze the relationship between various disasters and the tunnel project; 3 Geological mapping, prospecting information and various types of maps, and it shall analyze the accuracy and possible problems of the information, at the same time, it shall put forward plans to investigate; 4 Meteorological data like air temperature, precipitation, wind speed and wind direction in the tunnel area; 5 Information likes earthquake history and coefficient of peak acceleration of ground motion; 6 Traffic of areas along the line and their vehicles compositions and mineral resources; 7 The relevant Act and regulations 3.2.2 To collect information about social environment, construction conditions and neighborhood existing engineering. 3.3 Topography and geological survey

Contents of JTG D70-2004

Contents 1 General provision 2 Major terms and symbols 2.1 Terms 2.2 Symbols 3 Tunnel investigation and surrounding rock classification 3.1 General requirements 3.2 Collection of data 3.3 Topography and geological survey 3.4 Meteorological investigation 3.5 Environmental survey for the engineering 3.6 Surrounding rock classification 4 Overall designs 4.1 General requirement 4.2 Selection of tunnel site 4.3 Line shape design of tunnel 4.4 Design for cross section not the tunnel 4.5 Construction plan 5 Building material 5.1 General requirement 5.2 Material property 6 Loads 6.1 General requirement 6.2 Permanent load 6.3 Variable load 6.4 Accidental load 7 Tunnel adit and portal 7.1 General requirement 7.2 Tunnel adit engineering 7.3 Portal engineering 8 Design for lining structure 8.1 General requirement 8.2 Anchor-spray lining 8.3 Cast-in-place lining 8.4 Combined type lining 8.5 Open tunnel lining 9 Structural Calculations 9.1 General requirements 9.2 Lining calculation 9.3 Open tunnel calculation 9.4 Portal calculation 9.5 Structure requirement 10 Waterproofs and Drainage 10.1 General requirements 10.2 Waterproof 10.3 Drainage 10.4 Waterproof and drainage at the portal and open tunnel 11 Neighborhood and Multi-arch Tunnel 11.1 Neighborhood tunnel 11.2 Multi-arch tunnel 12 Secondary Channels 12.1 General requirements 12.2 Vertical shaft 12.3 Inclined shaft 12.4 Parallel pilot tunnel and horizontal tunnel 12.5 Horizontal adit, wind tunnel and underground machinery room 13 Ancillary works measures 13.1 General requirements 13.2 Ground stabilizing measures 13.3 Gushing water treatment measures 14 Special Geologic Districts 14.1 General requirements 14.2 Expansible surrounding rock 14.3 Solution cavity and worked-out section 14.4 Drift sand 14.5 Layer with gasses 14.6 Loess 14.7 Rock burst 15 Roadbed and pavement in the tunnel 15.1 General requirements 15.2 Roadbed 15.3 Pavement 16 Electromechanical Device and Other Facilities 16.1 Ventilation 16.2 Lighting 16.3 Traffic engineering 16.4 Other facilities Appendix A Relevant Regulations on Surrounding Rock Classification Appendix B Standard Inner Contour of the Tunnel Appendix C Natural Parameter Tables of Shapes Appendix D Calculation Method of Releasing Load Appendix E Calculation Method for Load of Shallow-buried Tunnel Appendix F Calculation Method of Lining Load of Tunnel with Unsymmetrical Pressure Appendix G Calculation Method for Design Load of Open Tunnel Appendix H Calculation Method of Soil Pressure Load of the Portal Appendix I Load-structure Method Appendix J Stratal Configuration Method Appendix K Calculation Methods for the Reinforcing Bars of Bending and Compression Reinforced Concrete Members Appendix L Explanation of Wording in this code