Detail of SL 551-2012

Introduction of SL 551-2012

1 General provisions 1.0.1 This standard is formulated, in accordance with the Regulations on safety administration of reservoir dams, with a view to strengthening the safety monitoring of earth-rockfill dam and guaranteeing the engineering safety. 1.0.2 This standard is mainly applicable to the classification of water conservancy and hydropower engineering and the safety monitoring of Classes 1, 2 and 3 rolled earth-rockfill dams in the design standard. It may also be referred to for safety monitoring of Classes 4 and 5 rolled earth-rockfill dams and other types of earth-rockfill dams. 1.0.3 The scope of monitoring in this standard covers the body, foundation and ends of the earth-rockfill dam, and the outlet structures and devices directly related to the safety of the dam, as well as the bank slope at the near-dam region that has a significant impact on the safety of the earth-rockfill dam. 1.0.4 Safety monitoring methods include patrol inspection and monitoring with instruments, which shall be used in combination. 1.0.5 The safety monitoring of earth-rockfill dam shall be based on the engineering grade, scale, structural type and its topographical and geological conditions and geographical environment, etc., and the necessary monitoring items and their corresponding facilities shall be set up for regular system monitoring. For various types of monitoring items and their settings, see Table A.1 of Annex A and related instructions. For the stability monitoring of the near-dam bank slope and underground caverns, special items may be selected according to the provisions of 4.6, 4.7, 5.6 and 5.7 of this standard and the specific conditions of the engineering. See Annex F and Annex G for details and requirements of seismic response monitoring and hydraulic observation of outlet structures. 1.0.6 The safety monitoring work of earth-rockfill dam shall follow the principles below: 1 The arrangement of monitoring instruments and facilities shall be closely combined with the specific conditions of the engineering, highlighting key points and taking into account all aspects. Relevant items shall be coordinated and arranged. 2 The selection of monitoring instruments and facilities shall be advanced and convenient for automatic monitoring under the premise of reliability, durability, economy and practicality. 3 The installation of monitoring instruments and facilities shall be put in place timely through professional construction to ensure quality. When the instruments and facilities are installed and buried, the impact on the main construction should be reduced, and the main construction shall provide the necessary conditions for the installation of instruments and facilities. 4 It shall be ensured that the necessary items can still be monitored under severe conditions. Special monitoring stations (rooms) and monitoring galleries can be provided when necessary. 1.0.7 The main technical indicators of monitoring instruments shall comply with the current national standards for dam monitoring instruments. Before the instruments are buried, they shall be inspected, calibrated and subject to waterproof treatment for cable joints. After buried, the instruments and facilities shall be well protected, and the survey form and the cable routing diagram shall be completed in time, which shall be handed over to the management organization for filing for future reference after passing the special acceptance. The requirements for cables and their joints are detailed in Annex A.3. 1.0.8 Fiducial values shall be determined duly for instrument monitoring, and the monitoring shall be performed at specified times. If any abnormality is found, monitor again immediately. The monitoring shall be continuous with true records and complete annotations which are collated in a timely manner. Once the problem is found, it shall be reported timely. The monitoring and reading instruments shall be regularly calibrated, and comparing monitoring shall be made at the time of replacement. The number of monitoring for different items at different stages is detailed in Table A.2 of Annex A. 1.0.9 The monitoring work at each stage shall meet the following requirements: 1 Feasibility study stage: the overall design scheme of the safety monitoring system, the main monitoring items and the number of instruments required, as well as the investment estimation (about 1% to 2.5% of the total investment in the main building) shall be presented. 2 Preliminary design stage: the overall design scheme of the safety monitoring system, the monitoring items and their layout shall be refined, and the specific quantity of the monitoring instruments and facilities and the investment budget shall be determined. For Classes I and II engineering, a special report on engineering safety monitoring design shall be submitted separately. 3 Bidding design stage: the monitoring system layout, technical indicators of instruments and facilities, list of monitoring projects, technical requirements of installation, monitoring frequency and engineering budget shall be proposed. For Classes I and II engineering, bidding documents for engineering safety monitoring shall be submitted separately.

Contents of SL 551-2012

< Foreword i 1 General provisions 2 Terms and definitions 3 Patrol inspection 3.1 General requirements 3.2 Inspection items and content 3.3 Inspection methods and requirements 3.4 Records and reports 4 Deformation monitoring 4.1 General requirements 4.2 Surface deformation of dam body 4.3 Internal deformation of dam body (foundation) 4.4 Deformation of impervious body 4.5 Deformation of interface, joint (crack) and voids 4.6 Deformation of near-dam bank slope 4.7 Deformation of surrounding rock of underground cavern 4.8 Monitoring data and results 5 Seepage monitoring 5.1 General requirements 5.2 Seepage pressure of dam body 5.3 Seepage pressure of dam foundation 5.4 Seepage around dam 5.5 Seepage flow 5.6 Seepage of near-dam bank slope 5.7 Seepage of underground cavern 5.8 Monitoring data and results 6 Pressure (stress) monitoring 6.1 General requirements 6.2 Pore water pressure 6.3 Soil pressure 6.4 Stress-strain and temperature 6.5 Monitoring data and results 7 Environmental monitoring 7.1 General requirements 7.2 Water level and reservoir water temperature 7.3 Precipitation and air temperature 7.4 Sediment accumulation in front of the dam (and in the dam area) and downstream scouring 7.5 Ice pressure 7.6 Monitoring data and results 8 Automatic monitoring system 8.1 General requirements 8.2 System equipment 8.3 System design 8.4 Installation and commissioning 8.5 Operation and management 9 Compilation and analysis of monitored data 9.1 General requirements 9.2 Basic project data and survey data of monitoring facilities 9.3 Sorting and compilation of monitored data 9.4 Data analysis Annex A General provisions Annex B Patrol inspection Annex C Deformation monitoring Annex D Seepage monitoring Annex E Pressure (stress) monitoring Annex F Seismic response monitoring Annex G Hydraulic observation of outlet structure Annex H Monitoring organization and instrument management Annex J Calculation equations Annex K (Informative) Figures and tables format Explanation of wording in this specification