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Engineering Construction Standard Full-text Information System
National Standard of the People's Republic of China
Architectural Code for Collapsible Loess Areas
GBJ25-90
1991Beijing
Engineering Construction Standard Full-text Information System
W Engineering Construction Standard Full-text Information System
National Standard of the People's Republic of China
Architectural Code for Collapsible Loess Areas
GBJ25—90
Editor Department: Shaanxi Provincial Planning Commission||tt| |Approving department: Ministry of Construction of the People's Republic of China Date of implementation: March 1, 1991
Engineering Construction Standards Full Text Information System
Engineering Construction Standards Full Text Information System
Notice on the release of "Architectural Code for Collapsible Loess Areas"
(90) Jianbiaozi No. 256
According to the requirements of the State Planning Commission's Document No. Jizong [1986] 250, the "Architectural Code for Collapsible Loess Areas" revised by the Shaanxi Provincial Planning Commission and relevant departments has been reviewed by relevant departments. The "Architectural Code for Collapsible Loess Areas" GBJ25-90 is now approved as a national standard and will be implemented on March 1, 1991. The original "Architectural Code for Collapsible Loess Areas" TJ25-78 will be abolished at the same time.
This code is managed by the Shaanxi Provincial Planning Commission, and its specific interpretation and other work are the responsibility of the Shaanxi Provincial Building Science Research and Design Institute. The publication and distribution is organized by the Standard and Quota Research Institute of the Ministry of Construction.
Ministry of Construction of the People's Republic of China
May 18, 1990
Engineering Construction Standards Full Text Information System
Engineering Construction Standards Full Text Information System
Revision Notes
According to the spirit of the State Planning Commission's Document No. 250 [1986], the Shaanxi Provincial Institute of Architectural Science Research and Design, together with relevant survey, design, material research and colleges and universities, formed a revision group to revise the original "Building Code for Collapsible Huangshi Areas" TJ25-78. During the revision process: opinions were widely solicited from relevant units across the country, and after many discussions and revisions, the Shaanxi Provincial Planning Commission organized the review and finalization. The revised code is divided into 6 chapters and 12 appendices. The main contents of the supplement and revision to the original code are:
1. Based on a large amount of engineering practice and building survey data, the comprehensive treatment measures are changed to comprehensive measures based on foundation treatment. 2. Added Chapter 4, Ground Treatment, and added 6 appendices, including explanation of terms, key points for taking original soil samples from boreholes, examples of various types of buildings, design measures for pool structures, bearing capacity of loess, and static load test of single pile immersion. 3. For soil layers below 10m below the base, the original fixed pressure of 300kPa is changed to the saturated deadweight pressure of the overlying soil to determine the collapsibility of loess. For newly accumulated loess with high compressibility, the regulation of using 150kPa pressure to determine the collapsibility coefficient for soil layers within 5m below the base is cancelled. For buildings with base pressure greater than 300kPa, the actual pressure is added to determine the collapsibility of loess.
4. For the boundary value of determining the type of site collapsibility, whether it is calculated deadweight collapsibility or measured deadweight collapsibility, 7cm is used as the standard. The regulation of comprehensive determination of 7 to 11cm is cancelled according to the calculated deadweight collapsibility.
5. In the formula for calculating the self-weight collapsibility, a correction coefficient β is added, which varies according to the soil type. By calculating the self-weight collapsibility, it is possible to avoid misjudging a non-self-weight collapsible loess site as a self-weight collapsible loess site, or misjudging a self-weight collapsible loess site as a non-self-weight collapsible loess site.
6. In the formula for calculating the total collapsible amount of the collapsible loess foundation from saturation to stable sinking, a correction coefficient β is added by taking into account factors such as the lateral extrusion and water immersion probability of the foundation soil.
7. According to the total collapsibility and the size of the calculated self-weight collapsibility, the foundation is divided into four collapsible grades: I (slight), I (medium), III (severe), and IV (very severe), and the provision of dividing the collapsible amount into six collapsible grades is cancelled. 8. For soils with natural water content less than the plastic limit water content, the bearing capacity of Huang Wang shall be determined according to the plastic limit water content; for soils with natural water content greater than 25%, the bearing capacity shall be determined according to the bearing capacity table of saturated Huang Wang (Appendix 10.2). 9. The three types of buildings, A, B, and C, shall be changed to four types, A, B, C, and D. In the A and B types of buildings, high-rise buildings and related regulations are added. 10. The design measures selection table is changed to clause expression. 11. In waterproofing measures, effective new waterproof materials and pipe-in-pipe leak detection facilities are introduced.
12. In foundation calculation, the calculation principles of collapsible deformation and compression deformation are clarified, and empirical coefficients suitable for settlement calculation in loess areas are proposed. In the process of implementing this specification, please combine engineering practice, carefully summarize experience, and please send relevant opinions and suggestions to Shaanxi Provincial Building Science Research and Design Institute, No. 142, Huancheng West Road, Xi'an at any time.
Shaanxi Provincial Planning Commission
March 1990
Engineering Construction Standard Full Text Information System
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Chapter 1 General
Chapter 2 Engineering Geological Survey
Section 1
General Provisions
Welcome to the Industry
Section 2. On-site Survey
Section 3 Collapsibility Evaluation.
Chapter 3 Design
Section 1
General Provisions
Section 2 Site Selection and Master Plan Design
Section 3
Section 4
Section 5
Section 6
Chapter 4
Architectural Design
Structural Design.*
Water Supply and Drainage, Heating and Ventilation Design
Foundation Calculation
Foundation Treatment
Section 1
Section 2
Section Section 3
Section 4
Section 5
Section 6
Section 7
General provisions.
Bedding method.…
Compaction method
Compaction method
Pile foundation
Pre-soaking method·
Single liquid silicification or alkali solution reinforcement method
Chapter 5
Section 1
Section 2bzxZ.net
Section 3
Section 4
General provisions·
On-site protection.
Construction of foundation pit or trench
Construction of buildings
Engineering construction standard full text information system
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Engineering construction standard full text information system
Section 5 Construction of pipelines and pools||tt ||Chapter VI Use and Maintenance
Section 1 General Provisions
Section 2 Maintenance and Repair
Section 3 Settlement Observation and Groundwater Level ObservationAppendix 1
Appendix 2
Appendix 3
Appendix 4
Appendix 5
Appendix 6
Appendix 7
Appendix 8
Terms of Explanation.
Physical and Mechanical Properties of Collapsible Loess and Collapsible Loess in China Sketch of engineering geological zoning
Stratigraphic division of loess
Provisions for distinguishing newly deposited loess Q
Operational points for taking undisturbed soil samples from boreholes
Loess collapsibility test·
Examples of various types of buildings
Design measures for pool-type structures
Appendix IX for non-self-weight collapsible loess sites when groundwater level rises
Design measures for buildings
Appendix X
Appendix X||| tt||Bearing capacity of Huangshi
Static load test of single pile immersed in water
Appendix 12
Additional explanation:
Explanation of terms used in this specification
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W.bzsoso.coI Engineering Construction Standard Full Text Information System
Main symbols
Foundation bottom area
Compression coefficient
Foundation bottom surface width
Cohesion
Foundation placement depth, pile diameter
Relative density of soil particles (specific gravity)
Compression modulus of soil
Porosity
Design value of foundation bearing capacity
Basic value of foundation bearing capacity
Standard value of foundation bearing capacity
Liquidity index| |tt||Plasticity index
Length of foundation bottom
Average pressure of foundation bottom
Average additional pressure of foundation bottom
Standard value of bearing capacity of soil at pile end
Standard value of friction of soil around pile
Soil saturation
Soil water content
Soil gravity density, referred to as soil weight
Weighted average weight of soil above foundation bottom and below groundwater level
Engineering construction standard full-text information system Assume standard full-text information system
Take effective weight
Pressure diffusion angle of foundation
Bearing capacity correction coefficient of foundation width
Bearing capacity correction coefficient of foundation burial depth
Empirical coefficient for settlement calculation
Shrinkage coefficient
Self-weight shrinkage coefficient
Calculate self-weight shrinkage
Measured self-weight shrinkage
Total shrinkage
Shrinkage starting pressure
Correction coefficients that vary according to soil quality and region|| tt||Correction coefficient for factors such as lateral extrusion and waterlogging probability of foundation soil Compaction coefficient
Engineering Construction Standard Full Text Information System
Engineering Construction Standard Full Text Information System
Chapter 1 General
Article 1.0.1 In order to ensure the safety and normal use of buildings in collapsible loess areas, comprehensive measures mainly based on foundation treatment should be taken according to the characteristics of collapsible loess and engineering requirements, and local conditions should be taken to prevent foundation collapse, so as to achieve advanced technology and economic rationality. This specification is specially formulated.
Article 1.0.2 This specification applies to the survey, design, foundation treatment, construction, use and maintenance of industrial and civil buildings (including structures) in collapsible loess areas. Article 1.0.3 Construction projects in collapsible loess areas should not only be implemented in accordance with the provisions of this specification, but also comply with the provisions of relevant current national standards and specifications. Engineering Construction Standard Full Text Information System
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Chapter 2
Engineering Geological Survey
Section 1 General Provisions
Article 2.1.1 The engineering geological survey should identify the following contents, and should make evaluations of the site and foundation and suggestions for foundation treatment measures in combination with the requirements of the building. 1. The age and origin of the loess layer.
2. The thickness of the collapsible loess layer.
3. The change of the collapsible coefficient with depth.
4. The plane distribution of the collapsible type and collapsible grade. 5. The possibility of groundwater level rise and fall and other engineering geological conditions. Article 2.1.2 The physical and mechanical properties of collapsible loess and the outline map of China's collapsible loess engineering geological division (see Figure 2.1) can be selected according to Appendix 2 of this specification. Article 2.1.3 The investigation stage can be divided into three stages: site selection or feasibility study, preliminary investigation, and detailed investigation. The investigation results of each stage shall meet the requirements of each design stage.
For areas with small site area, simple geological conditions or construction experience, the investigation stage can be simplified, but it shall meet the requirements of the two stages of preliminary investigation and detailed investigation. For buildings with complex engineering geological conditions or base pressure greater than 300kPa, construction investigation or special investigation is still advisable. Article 2.1.4 The preparation of the investigation work outline shall be carried out according to the following conditions and requirements: 1. Different investigation stages.
2. Existing engineering geological data and regional construction experience on the site and its vicinity. 3. The complexity of the engineering geological conditions of the site and the collapsible characteristics of loess. 4. Project scale, design and construction requirements. Article 2.1.5 The complexity of the engineering geological conditions of the site can be divided into the following three types: Engineering Construction Standard Full Text Information System
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1. Simple site: gentle terrain, simple landforms and strata, single type of collapsibility, and little change in the level of collapsibility.
2. General site: large terrain fluctuations, complex landforms and strata, local development of adverse geological phenomena, complex changes in types of collapsibility and levels of collapsibility. 3. Complex site: large terrain fluctuations, complex landforms and strata, widespread development of adverse geological phenomena, complex distribution of types of collapsibility and levels of collapsibility, and significant changes in groundwater levels.
Article 2.1.6 In addition to meeting general requirements, engineering geological surveying and mapping should also include the following contents:
1. Study the undulations of the terrain and the accumulation and discharge conditions of precipitation, and investigate the scope of mountain torrents and their occurrence time.
2. Divide different geomorphic units, find out the distribution, scale and development trend of adverse geological phenomena such as wet depressions, loess caves, landslides, collapses, gullies, mudslides and their impact on construction.
3. Divide loess layers according to Appendix 3 of this code, and determine the recent accumulation of loess Q% according to Appendix 4.
4. Investigate the depth of groundwater level, the amplitude of seasonal changes, the rise and fall trend, surface water bodies and irrigation conditions.
5. Investigate the current status of neighboring buildings.
6. Understand whether there are underground pits such as tombs, wells, pits, caves, tunnels, sand, and sand lanes in the site.
Article 2.1.7 When taking undisturbed soil samples, their natural humidity and structure must be maintained. When sampling in the exploration well, the vertical spacing should be 1m, and the diameter of the soil sample should not be less than 10cm; when sampling in the borehole, it should be strictly implemented in accordance with the requirements of Appendix 5 of this code. There should be a certain number of exploration wells at the soil exploration point. On the III and IV level self-weight collapsible loess sites, the number of exploration wells shall not be less than 1/3 of the soil exploration point. Article 2.1.8 After the exploration point is used, it shall be immediately backfilled and compacted with original soil in layers, and its dry density shall not be less than 1.5g/cm
Engineering Construction Standard Full Text Information System
W.bzsosO.cOArticle 2 The physical and mechanical properties of collapsible loess and the outline of the engineering geological zoning of collapsible loess in China (see Figure 2.1) can be selected according to Appendix II of this code. Article 2.1.3 The investigation stage can be divided into three stages: site selection or feasibility study, preliminary investigation, and detailed investigation. The investigation results of each stage should meet the requirements of each design stage.
For areas with small site area, simple geological conditions or construction experience, the investigation stage can be simplified, but it should meet the requirements of the two stages of preliminary investigation and detailed investigation. For buildings with complex engineering geological conditions or base pressure greater than 300kPa, construction investigation or special investigation should be carried out. Article 2.1.4 The preparation of the investigation work outline should be carried out according to the following conditions and requirements: 1. Different investigation stages.
2. Existing engineering geological data and regional construction experience on the site and its vicinity. 3. The complexity of the engineering geological conditions of the site and the collapsible characteristics of loess. 4. Project scale, design and construction requirements. Article 2.1.5 The complexity of the engineering geological conditions of the site can be divided into the following three types: Engineering Construction Standard Full Text Information System
W. Engineering Construction Standard Full Text Information System
1. Simple site: gentle terrain, simple landforms and strata, single type of collapsibility, and little change in the level of collapsibility.
2. General site: large terrain fluctuations, complex landforms and strata, local development of adverse geological phenomena, complex changes in types of collapsibility and levels of collapsibility. 3. Complex site: large terrain fluctuations, complex landforms and strata, widespread development of adverse geological phenomena, complex distribution of types of collapsibility and levels of collapsibility, and significant changes in groundwater levels.
Article 2.1.6 In addition to meeting general requirements, engineering geological surveying and mapping should also include the following contents:
1. Study the undulations of the terrain and the accumulation and discharge conditions of precipitation, and investigate the scope of mountain torrents and their occurrence time.
2. Divide different geomorphic units, find out the distribution, scale and development trend of adverse geological phenomena such as wet depressions, loess caves, landslides, collapses, gullies, mudslides and their impact on construction.
3. Divide loess layers according to Appendix 3 of this code, and determine the recent accumulation of loess Q% according to Appendix 4.
4. Investigate the depth of groundwater level, the amplitude of seasonal changes, the rise and fall trend, surface water bodies and irrigation conditions.
5. Investigate the current status of neighboring buildings.
6. Understand whether there are underground pits such as tombs, wells, pits, caves, tunnels, sand, and sand lanes in the site.
Article 2.1.7 When taking undisturbed soil samples, their natural humidity and structure must be maintained. When sampling in the exploration well, the vertical spacing should be 1m, and the diameter of the soil sample should not be less than 10cm; when sampling in the borehole, it should be strictly implemented in accordance with the requirements of Appendix 5 of this code. There should be a certain number of exploration wells at the soil exploration point. On the III and IV level self-weight collapsible loess sites, the number of exploration wells shall not be less than 1/3 of the soil exploration point. Article 2.1.8 After the exploration point is used, it shall be immediately backfilled and compacted with original soil in layers, and its dry density shall not be less than 1.5g/cm
Engineering Construction Standard Full Text Information System
W.bzsosO.cOArticle 2 The physical and mechanical properties of collapsible loess and the outline of the engineering geological zoning of collapsible loess in China (see Figure 2.1) can be selected according to Appendix II of this code. Article 2.1.3 The investigation stage can be divided into three stages: site selection or feasibility study, preliminary investigation, and detailed investigation. The investigation results of each stage should meet the requirements of each design stage.
For areas with small site area, simple geological conditions or construction experience, the investigation stage can be simplified, but it should meet the requirements of the two stages of preliminary investigation and detailed investigation. For buildings with complex engineering geological conditions or base pressure greater than 300kPa, construction investigation or special investigation should be carried out. Article 2.1.4 The preparation of the investigation work outline should be carried out according to the following conditions and requirements: 1. Different investigation stages.
2. Existing engineering geological data and regional construction experience on the site and its vicinity. 3. The complexity of the engineering geological conditions of the site and the collapsible characteristics of loess. 4. Project scale, design and construction requirements. Article 2.1.5 The complexity of the engineering geological conditions of the site can be divided into the following three types: Engineering Construction Standard Full Text Information System
W. Engineering Construction Standard Full Text Information System
1. Simple site: gentle terrain, simple landforms and strata, single type of collapsibility, and little change in the level of collapsibility.
2. General site: large terrain fluctuations, complex landforms and strata, local development of adverse geological phenomena, complex changes in types of collapsibility and levels of collapsibility. 3. Complex site: large terrain fluctuations, complex landforms and strata, widespread development of adverse geological phenomena, complex distribution of types of collapsibility and levels of collapsibility, and significant changes in groundwater levels.
Article 2.1.6 In addition to meeting general requirements, engineering geological surveying and mapping should also include the following contents:
1. Study the undulations of the terrain and the accumulation and discharge conditions of precipitation, and investigate the scope of mountain torrents and their occurrence time.
2. Divide different geomorphic units, find out the distribution, scale and development trend of adverse geological phenomena such as wet depressions, loess caves, landslides, collapses, gullies, mudslides and their impact on construction.
3. Divide loess layers according to Appendix 3 of this code, and determine the recent accumulation of loess Q% according to Appendix 4.
4. Investigate the depth of groundwater level, the amplitude of seasonal changes, the rise and fall trend, surface water bodies and irrigation conditions.
5. Investigate the current status of neighboring buildings.
6. Understand whether there are underground pits such as tombs, wells, pits, caves, tunnels, sand, and sand lanes in the site.
Article 2.1.7 When taking undisturbed soil samples, their natural humidity and structure must be maintained. When sampling in the exploration well, the vertical spacing should be 1m, and the diameter of the soil sample should not be less than 10cm; when sampling in the borehole, it should be strictly implemented in accordance with the requirements of Appendix 5 of this code. There should be a certain number of exploration wells at the soil exploration point. On the III and IV level self-weight collapsible loess sites, the number of exploration wells shall not be less than 1/3 of the soil exploration point. Article 2.1.8 After the exploration point is used, it shall be immediately backfilled and compacted with original soil in layers, and its dry density shall not be less than 1.5g/cm
Engineering Construction Standard Full Text Information System
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