HG/T 20548-1992 Design regulations for soft foundation treatment of chemical industry buildings
Some standard content:
Industry Standard of the People's Republic of China
HG20548-92
Design Provisions for Treatment of Soft Foundations of Chemical Industry Buildings
1993-04-27
1993-08-01
Ministry of Chemical Industry of the People's Republic of China
Industry Standard of the People's Republic of China
Design Provisions for Treatment of Soft Foundations of Chemical Industry Buildings
HG 20548-92
Editing Unit: Second Design Institute of Ministry of Chemical Industry
Approving Department: Ministry of Chemical Industry
Implementation Date: August 1, 1993
Engineering Construction Standard Editing Center of Ministry of Chemical Industry
According to the arrangement of the Infrastructure Department of the Ministry of Chemical Industry, the Architectural Design Technology Center of the Ministry of Chemical Industry organized the compilation of "Design Provisions for Treatment of Soft Foundations of Chemical Industry Buildings" (HG20548-92) as an industry standard for design application.
This standard was compiled by the Second Design Institute of the Ministry of Chemical Industry in accordance with the national standard "Code for Design of Building Foundations" (GBJ7-89) combined with the engineering practice summary of soft soil foundations in the chemical industry system over the years.
The draft for review was reviewed by the Technical Committee of the Central Station, and the reviewers were Zhang Gengrong and Zhang Dade. If any units have suggestions for improvement during use, please contact the Architectural Design Technology Central Station of the Ministry of Chemical Industry in a timely manner for reference during revision. Architectural Design Technology Center of the Ministry of Chemical Industry
December 1992
2 Basic Provisions
2.1 General Provisions
2.2 Treatment and Utilization of Soft Foundation
2.3 Selection of Foundation Treatment Methods
3 Foundation Treatment Methods
3.1 Heavy Hammer Ramming Method
Vibration Compaction Method
Soil Replacement Cushion Method
Lime Soil Well Column Method
Dynamic Ramming Method
Soil (Lime Soil, Two-Lime) Pile Compaction Method
Sand and Gravel Pile Method
|Vibration method
Preloading method
Deep mixing method
High-pressure jet grouting method
Anti-corrosion of foundation treatment
Architectural and structural measures for soft foundation
4.1Architectural measures
Structural measures
4.3Large-area ground load
Article explanation
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In order to ensure the safety, reliability, economic rationality and advanced technology of the design of soft foundation treatment for chemical buildings, this regulation is specially formulated.
1.0.2 The design of soft foundation treatment must adhere to the principles of advanced technology, adapting to local conditions, economic rationality, using local materials and reliable schemes; based on geological survey data, comprehensive comparison and careful design of factors such as project characteristics, structural type, material conditions and construction conditions. 1.0.3 These regulations are formulated in accordance with the current relevant national standards and in combination with the characteristics of chemical engineering buildings. Any matters not specified in these regulations shall be implemented in accordance with the relevant standards. When there are mature experiences or regulations in the area where the project is located, the local regulations shall be followed first.
2 Basic regulations
2.1 General regulations
2.1.1 Soft foundation refers to a foundation whose load-bearing layer is mainly composed of silt, silty soil, backfill, miscellaneous fill, plain fill or other highly compressible soil layers. When there is a highly compressible soil layer in the local range of the foundation, it should be considered as a local soft soil layer and local treatment should be performed. 2.1.2 If there is a layer with a standard bearing capacity value of less than 100kPa in the main load-bearing layer of the foundation, it should also be considered as a soft foundation.
2.1.3 The geological and hydrogeological survey reports should be carefully studied to analyze and identify the uniformity, composition, distribution range and properties of the soft soil layer, and understand the bearing capacity and compression modulus of the foundation soil layer as the basis for the design scheme. 2.1.4 When determining the design scheme for the soft foundation, a comprehensive analysis should be conducted based on the geological report, foundation conditions and the importance of the building, and sufficient technical and economic demonstration should be made. 2.2 Treatment and utilization of soft foundations
2.2.1 The foundation of a building can only be reinforced if it cannot meet the bearing capacity and deformation requirements after verification. When treating the foundation, the importance of the building and its sensitivity to settlement should be considered, and appropriate treatment methods should be adopted. The foundation treatment requirements for special soils such as collapsible loess and expansive soil should be implemented in accordance with the corresponding specifications.
2.2.2, Chemical buildings are divided into three safety levels according to their importance, as shown in Table 2.2.2.
Chemical building safety level
Building type and name
Important chemical buildings or buildings with special requirements for foundation settlement, such as compression workshops, urea granulation towers, synthesis frames, various tower equipment foundations and Class 1
Important compressor foundations
General chemical buildings and structures (multi-story workshops or frames with a total height of no more than 20m, single-story workshops with a span of no more than 24m, etc.)
Soft buildings
2.2.3 For Class I buildings, in addition to verifying the foundation bearing capacity, the foundation deformation should also be verified.
For Class II and Class D general buildings with low requirements for foundation deformation control, when they meet the conditions listed in Table 2.0.2 of the "Code for Design of Building Foundations" (GBJ7-89), it is not necessary to verify the deformation; if the foundation bearing capacity meets the requirements, the foundation can be left untreated, or simply treated according to the actual situation.
2.2.4 If a Class I building has any of the following conditions, it is still necessary to verify the foundation deformation: 2.2.4.1 The standard bearing capacity of the foundation of a building with a complex shape is less than 130kPa; 2.2.4.2 There is ground loading near the foundation or the load difference between adjacent foundations is large; 2.2.4.3 When the distance between adjacent buildings is too close and there is a possibility of tilting; 2.2.4.4 There is thick or uneven fill in the foundation. 2.2.5 The allowable value of the foundation deformation of the building shall be determined in accordance with the requirements of the "Design Regulations for Foundation Deformation of Chemical Buildings (Structures)" (HGJ24-89). When it is difficult to verify the tilt and settlement difference and only the settlement can be verified, the allowable settlement can be adopted according to Table 2.2.5. Allowable settlement of foundation
Building structure and foundation type
Brick boron bearing structure: Building length-to-height ratio: 34
Single-layer nested structure (column spacing 6m)
Multi-layer frame structure: Single foundation, strip foundation Xiao-style foundation
Box foundation
Tower equipment foundation
Exhaust pipe foundation
Smoke window foundation
Oil tank foundation (center)
Gas cabinet foundation (center)
Allowable settlement, mm
Note: When the multi-layer frame bears super-heavy chemical equipment such as synthesis tower, the table allowable settlement should be multiplied by 0.7.
2.2.6 When the bearing capacity and deformation of the building foundation meet the requirements, natural foundation should be used as much as possible. When using soft soil layers as bearing layers, the following provisions may be followed: 2.2.6.1 For silt and silty soil, it is advisable to make full use of the better soil layers overlying them as bearing layers. When the overlying soil layer is thin, care should be taken to avoid disturbing the silt and silty soil during construction.
2.2.6.2 Backfill soil, construction waste and industrial waste with stable performance can all be used as bearing layers when they have good uniformity and compactness. 2.2.6.3 For miscellaneous fill soils such as domestic waste with high organic matter content and industrial waste that has a slow erosion effect on the foundation, it is not advisable to use them as bearing layers without treatment. 4
2.2.7 When there are local soft soil layers, dark ponds and dark ditches in the foundation of a building, the following treatment methods may be adopted:
2.2.7.1 Deepening of foundation: Applicable to situations where the scope and depth to be treated are not large, the underlying soil layer is good, and there are conditions for deep excavation. After the local weak layer is excavated, the foundation is buried deep into the underlying soil layer.
2.2.7.2 Foundation span: Applicable to the situation where the scope to be treated is narrow and the depth is large. When the soft layer is deep and difficult to excavate, a local foundation beam span is used to transfer the upper load to the better soil layers on both sides. 2.2.7.3 Soil replacement cushion layer: Applicable to the situation where the scope to be treated is large, the treatment depth is small, the underlying soil layer is poor, and it cannot be directly used as the foundation bearing layer. The cushion layer material can be medium-coarse sand, angular gravel, crushed stone, slag, etc. 2.2.7.4-Short piles: Applicable to the situation where the depth to be treated is large, the foundation pit is difficult to drain, or it is not suitable for deep excavation.
2.3 Selection of foundation treatment methods
2.3.1 Foundation treatment can be divided into shallow treatment and deep treatment according to its treatment depth. Shallow treatment methods include: heavy hammer surface tamping method, soil replacement layer method, vibration compaction method, etc. Deep treatment methods include: strong tamping method, sandstone pile method, soil (lime, lime) pile compaction method, vibration impact method, lime well column method, preloading method, deep mixing method, high-pressure jet grouting method, etc. When selecting, shallow treatment should be given priority. Only when shallow treatment cannot meet the requirements can deep treatment be used.
2.3.2 Before determining the treatment method, the following work should be carried out: 2.3.2.1 Collect detailed engineering geological and hydrogeological data. 2.3.2.2. According to the design requirements of the project and the main problems of using natural foundations, determine the purpose, scope and technical indicators of foundation treatment after treatment.
2.3.2.3 Understand the foundation treatment experience and construction conditions in the region; for buildings with special requirements, the foundation treatment experience and effects of similar projects in other regions should be understood. 2.3.3 When considering the foundation treatment plan, the synergy of the superstructure, foundation, foundation and superstructure should be considered at the same time to determine a reasonable foundation treatment plan and superstructure system.
2.3.4 Determine the foundation treatment plan according to the following steps: 2.3.4.1 According to the structure type, load size and use requirements, combined with factors such as soil conditions, groundwater characteristics and environmental conditions, preliminarily select several foundation treatment methods for consideration.
2.3.4.2 For the various foundation treatment methods initially selected, a technical and economic analysis and comparison shall be carefully conducted from the aspects of reinforcement mechanism, scope of application, expected treatment effect, material source, material consumption, equipment conditions, construction progress and environmental impact, and the best foundation treatment scheme shall be selected. If necessary, a comprehensive treatment scheme consisting of two or more foundation treatment methods may be selected.
2.3.4.3 For the selected foundation treatment methods, field tests or experimental construction shall be carried out on representative sites, and necessary tests shall be carried out during the test to verify the design parameters and treatment effect. If they do not meet the design requirements, the design parameters shall be revised or other foundation treatment methods shall be used instead.
2.3.5 When initially selecting the foundation treatment method, it may be selected according to Table 2.3.5 based on the conditions of the foundation and the safety level of the building.
2.3.6 For production plants with acidic media, foundation treatment methods such as lime soil cushion, lime soil well column, and lime soil pile shall not be used.
2.3.7 For important chemical buildings (such as the main buildings and special structures of large-scale fertilizer plants and petrochemical plants), if the requirements for foundation deformation and stability are high and the general foundation treatment methods cannot meet the requirements, pile foundations should be used. 2.3.8 For factories or warehouses with large-area ground loads on soft soil foundations, if the ground load value is greater than 40kPa or the foundation deformation verification cannot meet the requirements of Article 4.3.3 of these regulations, the foundation should be treated. Treatment method: The preloading method or vibroflotation method can be used for the factory floor; the vibroflotation method or pile foundation can be used for the factory foundation. 6
m:
Applicable treatment
Miscellaneous fill
Saturated impact
fill and clay
Saturated
loose sand and
silt,
silty
collapsibility
3～~10
3～10bzxZ.net
Heavy hammer table
Table for selection of foundation treatment methods
Shallow treatment
Lime soil cushion
Note: I and I in the table are the safety levels of the buildings. 2.3.9 For the foundation of important large compressors, if the foundation is of high compressibility or poor stability, pile foundation should be adopted.
2.3.10 For the foundation of oil tanks or gas tanks, when it is located in silt mud soil or saturated soft clay foundation, water preloading method should be adopted first. 7
3 Foundation treatment method
3.1 Heavy hammer surface tamping method
3.1.1 Heavy hammer surface tamping method is suitable for reinforcing slightly wet clay, sand, plain fill, miscellaneous fill and collapsible loess. The groundwater level of the site should be below the effective influence depth of heavy hammer tamping.
3.1.2 The weight of the hammer can be 15~30kN, the unit static pressure of the hammer bottom should be 15kPa~20kPa, and the drop distance can be 3.5m~4.5m. At this time, the effective compaction depth is generally 1.2m~1.5m.
3.1.3 Before heavy tamping construction, a trial tamping should be carried out on site to determine the drop distance of the tamping hammer, the minimum number of tamping times, the total settlement, the average settlement of the last two times, and the effective compaction depth. The trial tamping area should not be less than 10m×10m. The average settlement of the last two times should be: for clay and collapsible loess
10mm-~20mm;
5mm--10mm.
3.1.4 In order to achieve a better compaction effect, the base soil should be kept in the best moisture content state as much as possible during tamping. The best moisture content of soil should be obtained according to the indoor compaction test. For ease of use, the optimum moisture content of the clay soil can be 0.6WL. If the soil moisture content is more than 2% lower than the optimum moisture content, water should be injected into the foundation pit to make the soil close to the optimum moisture content.
3.1.5 The range of heavy tamping should be larger than the foundation edge, and each side should exceed the foundation outer edge by 0.5m. When there are many equipment foundations in the factory or the water consumption is large, the foundation should be treated as a whole. 85m～4.5m, at this time the effective solid depth is generally 1.2m~1.5m.
3.1.3 Before heavy tamping construction, a test tamping should be carried out on site to determine the tamping hammer drop distance, the minimum number of tamping times, the total settlement, the average settlement of the last two times and the effective tamping depth, etc. The test tamping area should not be less than 10m×10m. The average settlement of the last two times should be: cohesive soil and collapsible loess
10mm-~20mm;
5mm--10mm.
3.1.4 In order to achieve a better tamping effect, the base soil should be kept in the best water content state as much as possible during tamping. The best water content of soil should be obtained according to the indoor compaction test. For ease of use, the best water content of cohesive soil can be 0.6WL. If the water content of the soil is more than 2% lower than the best water content, water should be injected into the foundation pit to make the soil close to the best water content.
3.1.5 The tamping range should be larger than the foundation edge, and each side should exceed the foundation outer edge by 0.5m. When there are many equipment foundations in the factory or the water consumption is large, the foundation should be treated as a whole.5m～4.5m, at this time the effective solid depth is generally 1.2m~1.5m.
3.1.3 Before heavy tamping construction, a test tamping should be carried out on site to determine the tamping hammer drop distance, the minimum number of tamping times, the total subsidence, the average subsidence of the last two times and the effective tamping depth, etc. The test tamping area should not be less than 10m×10m. The average subsidence of the last two times should be: cohesive soil and collapsible loess
10mm-~20mm;
5mm--10mm.
3.1.4 In order to achieve a better tamping effect, the base soil should be kept in the best water content state as much as possible during tamping. The best water content of soil should be obtained according to the indoor compaction test. For ease of use, the best water content of cohesive soil can be 0.6WL. If the water content of the soil is more than 2% lower than the best water content, water should be injected into the foundation pit to make the soil close to the best water content.
3.1.5 The tamping range should be larger than the foundation edge, and each side should exceed the foundation outer edge by 0.5m. When there are many equipment foundations in the factory or the water consumption is large, the foundation should be treated as a whole.
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