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Delivery: <= 11 days. True-PDF full-copy in English will be manually translated and delivered via email. GB 50497-2019: Technical code for monitoring of building excavation engineering Status: Valid GB 50497: Historical versions
Basic dataStandard ID: GB 50497-2019 (GB50497-2019)Description (Translated English): Technical code for monitoring of building excavation engineering Sector / Industry: National Standard Classification of Chinese Standard: P22 Classification of International Standard: 93.020 Word Count Estimation: 109,121 Date of Issue: 2019-11-22 Date of Implementation: 2020-06-01 Issuing agency(ies): Ministry of Housing and Urban-Rural Development of the People's Republic of China; State Administration for Market Regulation GB 50497-2019: Technical code for monitoring of building excavation engineering---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.1 General 1.0.1 In order to standardize the monitoring work of building foundation pit engineering, ensure the quality of monitoring, provide the basis for information-based construction and optimal design, achieve reliable results, advanced technology, and reasonable economy, ensure the safety of building foundation pits and protect the surrounding environment of foundation pits, formulate this standard. 1.0.2 This standard is applicable to the monitoring of building foundation pits and the surrounding environment. For excavation projects in special soils and erosive environments such as expansive soil, collapsible loess, red clay, permafrost, saline soil, and highly sensitive soft soil, monitoring should be carried out in combination with local engineering experience. 1.0.3 Foundation pit engineering monitoring should comprehensively consider factors such as foundation pit engineering design scheme, geotechnical engineering conditions of the construction site, surrounding environmental conditions, construction scheme, formulate a reasonable monitoring scheme, and carefully organize and implement monitoring. 1.0.4 In addition to complying with this standard, the monitoring of foundation pit engineering shall also comply with the current relevant national standards. 2 terms 2.0.1 building excavation In order to carry out the construction of the underground part of the building (structure), the space excavated from the ground is called the foundation pit for short. 2.0.2 surroundings around excavation In the construction and use phase of building foundation pits, the collective designation of existing buildings (structures), facilities, pipelines, roads, rock and soil bodies, and water systems around the foundation pit that may be affected by the foundation pit or that may affect the foundation pit. 2.0.3 Monitoring of excavation engineering During the construction and use phase of building foundation pits, regular or continuous inspections, measurements, monitoring and data collection are carried out on the safety status, changing characteristics and development trends of foundation pits and surrounding environments by means and methods such as instrument measurement and on-site inspections, analysis, feedback activities. 2.0.4 rock mass excavation A foundation pit where the rock is outcropped on the ground or the rock mass is covered with a small amount of soil. 2.0.5 soil-rock combinational excavation Within the range of excavation depth, the upper part is the soil mass and the lower part is the rock mass. It is necessary to consider the influence of the soil mass on the stability of the supporting structure. 2.0.6 design safety grade of excavation The safety level of the foundation pit determined by the foundation pit engineering design document. 2.0.7 bracing and retaining structure In order to ensure the safety of foundation pit excavation and underground structure construction and protect the surrounding environment of the foundation pit, a structural system that supports and reinforces the side walls of the foundation pit includes enclosure walls and support (or anchor) systems. 2.0.8 retaining wall The vertical structure that bears the earth pressure, water pressure and ground load within a certain range around the foundation pit. 2.0.9 Support bracing The component or structural system used to bear the load transmitted from the retaining wall in the foundation pit. 2.0.10 monitoring point monitoring point Observation points that are directly or indirectly set on the monitoring object and can reflect its changing characteristics. 2.0.11 Monitoring frequency frequency of monitoring The number of observations made to a monitoring point within a certain period of time. 2.0.12 Forewarning value on monitoring According to the protection requirements of the foundation pit and the surrounding environment, the warning value set for the monitoring items. 3 Basic Regulations3.0.1 The following foundation pits shall be monitored for foundation pit engineering. 1 The design safety level of the foundation pit is one or two foundation pits. 2 The following foundation pits whose excavation depth is greater than or equal to 5m. 1) Soil foundation pit; 2) Extremly soft rock foundation pit, broken soft rock foundation pit, extremely broken rock mass foundation pit; 3) The upper part is soil, and the lower part is a soil-rock composite foundation pit composed of extremely soft rock, broken soft rock, and extremely broken rock mass. 3 Foundation pits whose excavation depth is less than 5m but with complex geological conditions and surrounding environment 3.0.2 The design documents of foundation pit engineering shall specify the scope of monitoring, monitoring items and arrangement of measuring points, monitoring frequency and monitoring and early warning value. 3.0.3 Before the construction of the foundation pit project, the construction party shall entrust a third party with corresponding capabilities to carry out on-site monitoring of the foundation pit project. The monitoring unit shall prepare a monitoring plan, which shall be approved by the construction party and the designer, and shall be implemented after consultation with relevant management units involved in the surrounding environment of the foundation pit if necessary. 3.0.4 The monitoring work steps should meet the following requirements. 1 On-site survey and data collection; 2.Develop a monitoring program; 3 Layout and acceptance of reference points, working reference points and monitoring points, calibration of instruments and equipment and calibration of components; 4 Implement on-site monitoring; 5.Processing, analysis and information feedback of monitoring data; 6 Submit periodic monitoring results and reports; 7 After the on-site monitoring work is completed, submit complete monitoring data. 3.0.5 Before the monitoring program is compiled, the entrusting party shall provide the following information. 1 Geotechnical investigation report; 2 foundation pit support design documents; 3 Construction plan or construction organization design of foundation pit engineering; 4 Relevant data of each monitoring object in the surrounding environment; 5 other required information. 3.0.6 The monitoring unit should include the following main tasks in the stage of on-site survey and data collection. 1 Understand the monitoring requirements of the construction party and relevant units; 2 Collect and analyze geotechnical engineering investigation, hydrometeorology, surrounding environment, design, construction and other data; 3 Understand the design and construction of adjacent projects; 4 Through on-site survey, review the relationship between relevant data and on-site conditions, and determine the feasibility of on-site implementation of the proposed monitoring project. 3.0.7 The monitoring program should include the following. 1 Project overview; 2 Site engineering geology, hydrogeological conditions and environmental conditions around the foundation pit; 3 monitoring purpose; 4 basis for preparation; 5.Monitoring scope, objects and items; 6.Layout requirements of datum point, working datum point and monitoring point, and layout of measuring points; 7 Monitoring method and accuracy level; 8 The main instruments and equipment used by monitoring personnel; 9 monitoring period and monitoring frequency; 10 Monitoring data processing, analysis and information feedback; 11 Monitoring measures for early warning, abnormal and dangerous situations; 12 Quality management, monitoring operation safety and other management systems. 3.0.8 The monitoring scope of the foundation pit project should be comprehensively determined according to the design depth of the foundation pit, geological conditions, surrounding environment, support structure type, and construction method; During blasting excavation, the monitoring range of blasting vibration should be determined through blasting tests in accordance with the relevant provisions of the current national standard "Blasting Safety Regulations" GB 6722 and combined with the actual situation of the project. 3.0.9 The objects of on-site monitoring should include. 1 support structure; 2 Foundation pit and surrounding rock and soil mass; 3 Groundwater; 4 Protected objects in the surrounding environment, including surrounding buildings, pipelines, rail transit, railways and important roads, etc.; 5 Other objects to be monitored. 3.0.10 The monitoring schemes of the following foundation pit projects shall be subject to special demonstration. 1 Foundation pit engineering with serious damage consequences adjacent to important buildings, facilities, pipelines, etc.; 2 Foundation pit engineering with complex engineering geology and hydrogeology; 3 A serious accident has occurred and the foundation pit project has been reorganized; 4 First- and second-level foundation pit projects using new technologies, new processes, new materials, and new equipment; 5.Other foundation pit projects that need to be demonstrated. 3.0.11 The monitoring unit shall carry out monitoring according to the monitoring plan. When there is a major change in the design or construction of the foundation pit project, the monitoring unit should study with the construction party and related units and adjust the monitoring plan in time. 3.0.12 The monitoring unit shall process and analyze the monitoring data in a timely manner, and provide feedback on the monitoring results and evaluation to the construction party and relevant units in a timely manner. 3.0.13 During the monitoring period, the monitoring party should do a good job in the protection of monitoring facilities. The construction party and the general contractor shall assist the monitoring unit to protect the monitoring facilities. 3.0.14 Automatic monitoring should be implemented when the following requirements are met. 1 Monitoring items requiring high-frequency or continuous real-time observation; 2 Monitoring items that environmental conditions do not allow or cannot be observed manually. 3.0.15 The excavation engineering that implements automatic monitoring shall meet the following requirements. 1 The automatic monitoring system shall include monitoring instruments and equipment, automatic data collection system, data transmission system, data storage management system and real-time release system, etc.; 2.The accuracy and range of automatic monitoring equipment should meet the engineering requirements; 3 The automatic monitoring system should be able to perform automatic early warning or fault display in case of abnormal data. 3.0.16 At the end of the monitoring stage, the monitoring unit shall provide the construction party with a monitoring summary report and file the following data. 1 monitoring programme; 2 Reference point, monitoring point arrangement and acceptance record; 3 Periodic monitoring reports; 4 Monitoring summary report.4 Monitoring items4.1 General provisions 4.1.1 The monitoring items should match the foundation pit engineering design and construction plan; key observations should be made on the key parts of the monitoring objects; the selection of each monitoring item should be conducive to the formation of a monitoring system that complements and verifies each other. 4.1.2 On-site monitoring of foundation pit engineering should adopt the method of combining instrument monitoring and on-site inspection. 4.2 Instrument monitoring 4.2.1 Instrument monitoring items for soil foundation pit engineering shall be selected according to Table 4.2.1. 4.2.2 Rock mass foundation pit engineering instrument monitoring items should be selected according to Table 4.2.2. 4.2.3 The soil-rock composite foundation pit project shall be based on the design safety level of the foundation pit, rock mass quality, soil-rock distribution, soil-rock joint surface and groundwater conditions, support forms, and deformation control requirements of the surrounding environment, in accordance with Section 4.2.1 of this standard. Article 4.2.2 Select the monitoring item, and the horizontal displacement of the rock mass at the rock-socketed place of the retaining pile should be monitored. 4.2.4 When rock mass foundation pits and soil-rock combination foundation pits are excavated by blasting, particle vibration velocity or acceleration monitoring should be carried out for buildings (structures), bridges, roads, pipelines and other protected objects within the impact range of blasting vibration. 4.2.5 For collapsible loess and expansive soil foundation pits, when the possibility of waterlogging of the pit wall soil is high, it is advisable to monitor the water content of the soil. 4.2.6 When there are subways, tunnels or other buildings and facilities with special requirements for displacement around the foundation pit, the monitoring items should be determined through consultation with relevant management departments or units. 4.3 Inspection tour 4.3.1 During the construction and use period of the foundation pit project, special personnel should conduct inspections every day. 4.3.2 The patrol inspection of foundation pit engineering should include the following contents. 1 Support structure. 1) Forming quality of supporting structure; 2) Whether there are cracks in crown beams, supports, purlins or waist beams; 3) The continuity of crown beams, purlins or waist beams, and whether there is excessive deformation; 4) The closeness between purlins or girders and retaining piles, and the fall prevention measures for purlins and supports; 5) Check whether the backing plate of the anchor bolt is loose or deformed; 6) Whether the column is tilted, subsidence or bulge; 7) Whether the water-stop curtain is cracked or leaking water; 8) Whether there is soil gushing, quicksand and piping in the foundation pit; 9) Whether the surface layer is cracked or peeled off. 2 Construction status. 1) Whether there is any difference between the exposed rock and soil condition after excavation and the geotechnical investigation report; 2) Whether the excavation section length, layer thickness and support (bolt) setting are consistent with the design requirements; 3) Whether the exposed surface of the excavation of the side wall of the foundation pit is closed in time; 4) Whether the support and anchor rods are constructed in a timely manner; 5) Whether the water interception and drainage measures of the slope, side wall and surrounding surface are in place, and whether there is water accumulation at the side of the pit or at the bottom of the pit; 6) Whether the foundation pit dewatering and recharging facilities are operating normally; 7) Whether the ground around the foundation pit is overloaded. 3 surrounding environment. 1) Whether the surrounding pipelines are damaged or leaked; 2) Whether there is subsidence, cracks and slippage of the soil behind the retaining wall; 3) Whether there are new cracks in the surrounding buildings; 4) Whether the surrounding roads (ground) have cracks or subsidence; 5) Changes in adjacent foundation pit construction (heap loading, excavation, precipitation or recharge, piling, etc.); 6) Changes in the water level of adjacent water bodies (lakes, rivers, reservoirs, etc.) with hydraulic connections. 4 Monitoring facilities. 1) Integrity of reference points and monitoring points; 2) Monitor the integrity and protection of components; 3) Whether there are obstacles affecting the observation work. 5.Other patrol inspection contents determined according to design requirements or local experience. 4.3.3 In addition to complying with the provisions of Article 4.3.2 of this standard, the patrol inspection of special soil foundation pit engineering shall also meet the following provisions. 1 For expansive soil, collapsible loess, red clay, and saline soil, it is important to inspect whether the protection facilities such as waterproofing and drainage in the site are in good condition, and whether the exposed surface of the excavation is soaked by rainwater and various water sources, and whether it is timely cover closure; 2 Whether there is a large original crack surface when the expansive soil foundation pit is excavated, and whether there are moisturizing measures for the slope surface in the season of severe dry-wet cycle; 3 For temperature-sensitive soils such as permafrost and seasonally frozen soil, when the foundation pit undergoes freeze-thaw cycles during construction and use, it is necessary to focus on inspecting whether the heat preservation and heat insulation measures for the exposed surface of the excavation are in place, and whether the drainage at the top and foot of the slope is adequate. Whether the system facilities are in good condition; 4 For highly sensitive soft soil, it is necessary to focus on inspecting the construction disturbance, whether the support is implemented in a timely manner, whether there is soft soil extrusion on the side wall, and whether the exposed surface of the excavation is closed in time, etc. 4.3.4 In addition to complying with the provisions of Article 4.3.2 of this standard, inspection inspections of rock mass foundation pits and soil-rock combination foundation pits shall also comply with the following provisions. 1.Occurrence and water content of structural planes of rock mass; 2.When the supporting form of hanging piles is adopted, whether the rock mass at the rock abutment is cracked or lost; 3 Whether the rock mass is loose after blasting. 4.3.5 The patrolling inspection should be based mainly on visual inspection, supplemented by tools such as hammer, drill, measuring ruler, magnifying glass, etc., as well as equipment such as camera and photography. 4.3.6 The inspections of natural conditions, support structures, construction conditions, surrounding environment, monitoring facilities, etc. should be recorded, sorted out in time, and comprehensively analyzed with instrument monitoring data. If any abnormal situation is found, it should be timely Notify the construction party and other relevant units.5 Monitoring point layout5.1 General provisions 5.1.1 The layout of monitoring points should be able to reflect the actual state of the monitoring object and its changing trend. The monitoring points should be arranged on the key points and characteristic points of the monitoring object's force and deformation, and should meet the monitoring requirements of the monitoring object. 5.1.2 The arrangement of monitoring points should not hinder the normal work of the monitoring objects, and should be convenient for monitoring and protection. 1.The plane position of the monitoring section should be arranged in places where the stress and soil conditions change greatly or other representative parts; 2 In terms of plane layout, there should be no less than 2 monitoring sections on each side of the foundation pit, and the distance between monitoring points in vertical layout should be 2m~5m, and the lower part should be denser; 3 When laying out according to the distribution of soil layers, the number of measuring points laid out for each layer of soil should not be less than one, and should be arranged in the middle of each layer of soil. 5.2.9 The pore water pressure monitoring section should be arranged in the stress-bearing, large-deformation or representative parts of the foundation pit. 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