1. Scope
The standard specifies the requirements in design, construction, monitoring survey and detection of power engineering ground treatment. The power engineering in this standard includes production, auxiliary production and subsidiary production buildings in coal-fired, oil-fired, and gas fired fossil fuel power plants, subsidiary buildings (structure) for desulfurization and denitration, and power supply and transformation facilities.
This standard is applicable to design, construction, monitoring survey and detection of power engineering construction, extension and renovation ground treatment, and ground treatment of other power engineering may reference this standard.
2. Normative References
The following documents contain contents which, through reference in this text, composite provisions of this standard. For dated reference, subsequent amendments (excepting corrigenda content) to, or revisions of, any of these publications do not apply. Parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. For undated references, the latest editions of the normative documents referred to apply in the standard.
GB 13476 Pretensioned Spun Concrete Pile
GB 50007-2002 Code for Design of Building Foundation
GB 50011-2001 Code for Seismic Design of Buildings
GB 50021 Code for Investigation of Geotechnical Engineering
GB 50202 Code for Acceptance of Construction Quality of Building Foundation
GB 50204 Code for Acceptance of Constructional Quality of Concrete Structures
DL/T 5022-1993 Technical Stipulation for the Design of Civil Structure of Thermal Power Plant
JGJ 79 Technical Code for Ground Treatment of Buildings
JGJ 94-1994 Technical Code for Building Pile Foundations
JGJ 106-2003 Technical Code for Testing of Building Foundation Piles
JTJ/T 256 Specifications for Construction of Plastic Drainage Boards
JTJ/T 257 Quality Inspection Specifications for Plastic Drainboard
JTJ 298 Code of Design and Construction of Breakwaters
YB 9258 Code for Technique of Building Foundation Pit Engineering
3. Terms, Definitions and Symbols
3.1 Terms
This following terms and definitions are applicable to this standard:
3.1.1 Ground Treatment
It is referred to the foundation soil reinforcement method to improve the foundation soil strength, and soil deformation or penetrability, when the property of natural subsoil cannot meet the engineering requirements.
3.1.2 Subgrade foundation soil
It is referred to the earth mass or rock mass directly bearing the building foundation.
3.1.3 Foundation
It is referred to the structure part transferring actions that the structure bears to the subgrade foundation soil.
3.1.4 Characteristic value of subsoil bearing capacity
It is referred to the pressure value corresponding to the deformation specified in linear deformation section of the foundation soil pressure deformation curve measured in the loading test.
3.1.5 Allowable Subsoil Deformation
It is referred to the deformation controlling value to guarantee the normal condition of buildings.
3.1.6 Composite subgrade, composite foundation
It is referred to the artificial foundation that the foundation soil mass and the reinforcement interact each other or bear the load jointly. The soil in the artificial foundation is treated with ground treatment, reinforcement and displacement, or added with reinforcement material.
3.1.7 Pile Foundation
It is referred to the foundation that foundation pile arranged in rock-soil, and cushion cap connecting pile tops.
3.1.8 Composite Pile Foundation Controlled by Settlement
It is referred to the low cushion cap floating pile foundation which the topside load is born by foundation soil and pile, and which the pile number is determined according to the settlement control requirement.
3.1.9 Vertical ultimate bearing capacity of single pile
It is referred to the peak load that an individual pile is close to the collapse condition or appears the deformation that is not suitable to kept bearing under the vertical load or, and this value depends on the supporting resistance of soil on the pile and the materials strength of the pile foundation.
3.1.10 Consolidation
It is referred to the process that the void water in earth mass is discharged, the excess pore water pressure is vanished gradually, and the effective stress is increased as well.
3.1.11 Prototype Test
One or several foundation schemes featured in reliability and economic feasibility are recommended through the scheme suitability analyses and comparison. The present full-scale tests are taken out according to the practical engineering working condition.
3.2 Symbols
The following symbols are applicable to the standard:
A——Foundation base area;
——Treated foundation area shared by stump
——Pile sectional area
b——Foundation base width;
——Vertical consolidation coefficient of foundation soil;
——Horizontal consolidation coefficient of foundation soil;
c——Four-bladed vane shearing strength (vane strength) of foundation soil;
D——Effective influence depth of heavy-tamping; bell-end diameter of belled pile;
——Relative compaction of sandy soil;
d——Pile diameter or pile width, soil size (particle diameter);
——Equivalent circle diameter of treated foundation area shared by stump, effective drainage diameter;
——Soil particle relative density (specific gravity);
——Composite foundation compressive modulus;
——Compressive modulus of pile soil;
——Pile body compressive modulus;
——Foundation soil pore-solids ratio;
——Safety coefficient;
——Static-penetrate frictional resistance of sidewall;
——Design value of concrete uniaxial compressive strength;
——Unconfined compressive strength standard value of indoor soilcement test block;
——Characteristic value of subsoil bearing capacity;
——Characteristic value of bearing capacity of pile body unit cross-sectional area;
——Bearing capacity characteristic value of pile soil;
——Bearing capacity characteristic value of composite foundation;
——Plasticity index;
k——Permeability coefficient of soil layer;
l——Foundation base length, pile length;
m——Area displacement ratio;
O——Geotextile pore size;
p——Average additional pressure corresponding to foundation base of loading effect standard combination;
——Self-weight pressure of foundation base soil, soil pre-consolidation pressure;
——Self-weight pressure of underlayer base soil;
——Ultimate vertical bearing capacity of a single pile;
——Total ultimate shaft resistance of single pile;
——Total ultimate tip resistance of single pile;
——Ultimate shaft resistance of the i soil layer soil of the pile side;
——Ultimate tip resistance of pile tip soil;
——Bearing capacity characteristic value of pile tip soil;
——Friction force characteristic value of pile-periphery soil;
——Characteristic value of the vertical bearing capacity of a single pile;
——Drill tip static-penetrate resistance;
s——Pile spacing interval, settling volume;
U——Foundation soil consolidation degree;
u——Pile perimeter;
W——Hammer ram weight;
——Optimum moisture content of foundation soil
z——Thickness of replacement cushion under foundation base, thickness of soil layer;
——Pressure diffusion angle;
——Compacting coefficient;
——Dry Density.
4. General Provisions
4.0.1 The standard is formulated to enable pile foundation engineering and construction to comply with national technical economy politics, and to be of safety and usability, state-of-art technology, economic feasibility, quality guaranteeing and environment protection.
4.0.2 Besides the engineering design requirements, the power engineering ground treatment must stick to the principle of adjusting measures to local conditions, using local materials, environment protection and resources conservation.
4.0.3 The implementation of this standard shall meet the relative current national standard in geotechnical exploration survey and foundation design, and comply with local and professional standards in exploration survey, foundation design and construction technology, as well as construction quality acceptance standard.
4.0.4 In the ground treatment, the supervision of geotechnical engineering shall be taken out in accordance with relative regulations.
4.0.5 Expenses in design, test, construction, monitoring survey, detection and supervision of the ground treatment shall be listed in the engineering estimate and budgets.
5. General Requirements
5.0.1 The safety class of power engineering buildings (structure) shall be determined in accordance with DL-T 5022 and other relative regulations. And the foundation design level shall be determined in accordance with GB 50007.
5.0.2 The selection of ground treatment scheme shall be taken out according to site geotechnical engineering condition, building safety class, structure type, intensity of loading, combined action of topside structure and foundation, as well as local ground treatment experience, local construction condition and rock-soil environmental condition change during the building usage. After the technical and economic comparison, the ground treatment scheme or the scheme of topside structure reinforcement and ground treatment combination shall be adopted based on that the scheme is of reliable technology, and meet the requirements of engineering design and construction progress. The adopted ground treatment method shall meet the requirement of environmental protection, and avoid surface water and underground water pollutions due to the ground treatment; avoid damages of nearby buildings (structure) due to the base soil deformation; prevent adverse effect on surrounding environment due to vibration noise and fly ash.
5.0.3 If the power engineering is under one of the following conditions, the ground treatment shall be taken out:
1 The natural subsoil bearing capacity or its deformation cannot meet the engineering requirements;
2 Covered gutter, hidden lakes, hidden creek, earth cave or karst cave exist in foundation;
3 The foundation in seismic area where the liquefiable soil layer is available cannot meet the requirements of anti-liquefaction;
4 Through the technical and economic comparison, treated foundation is more reasonable and suitable than natural foundation.
5.0.4 The power engineering ground treatment shall be elaborated according to the engineering exploration survey design stages and implemented by steps.
5.0.5 The planning and the execution of the ground treatment may be taken out in the following order:
1 Analyses the condition of site as natural foundation and main existing problems according to the geotechnical survey data and the requirement of building on land; definite name, characteristic and external conditions of the building treated with ground treatment, as well as technical criteria that the ground treatment shall meet. Several alternative ground treatment schemes shall be selected preliminarily.
2 Combined with the site geotechnical engineering condition, analyses and compare the selected preliminarily ground treatment schemes, and selected the best ground treatment method from the technical economic aspects such as reinforcement principle, applicable scope, expected treatment effect, implement condition, construction duration and construction cost.
3 Combined with the geotechnical engineering exploration survey at power engineering preliminary design stage, take out necessary ground treatment prototype test to obtain necessary design parameters and appropriate construction scheme.
4 Complete the ground treatment working drawing design, and propose the requirements of supervision and monitoring survey during the construction and operation periods.
5.0.6 As for the power engineering ground treatment, a ground treatment method shall be adopted for same building foundation, and two or more methods may be combined comprehensively if necessary.
5.0.7 If difficult ground and new dredger fill freshly settled on the offshore and in riverine regions, or difficult ground needing filling are adopted as the building foundation, the site pretreatment should be taken out.
5.0.8 The prototype test shall be taken out for the Class I and II buildings (structure) of large and medium-sized power engineering. And the prototype test of the ground treatment should be taken out for expansion project which the engineering condition is changed greatly.
5.0.9 As for the working drawing design of the ground treatment, the sufficient geotechnical engineering data must be available. If the preexisting data cannot meet the design requirement, special geotechnical engineering explorations and tests shall be taken out additionally.
5.0.10 Previous to the formal construction of the ground treatment, the trial construction should be taken out. And the formal construction of the ground treatment may be carried out when the construction technology condition meets the design requirements.
5.0.11 In the ground treatment, the construction quality shall be controlled and the treatment effect shall be inspected. If the detection result indicates that the treated foundation cannot meet the design requirements, the reasons shall be ascertained and the reinforcement measures shall be taken out or the design parameter shall be adjusted.
5.0.12 As for the ground treatment construction, the detailed preparations for construction, construction quality control and quality assurance measures shall be available. The special crew shall be in charge of the construction inspection and quality supervision, make construction records, and report the abnormal condition to the relative departments and study the solutions together.
5.0.13 The monitoring survey and detection shall be taken out during and after the ground treatment construction. As for Class I buildings, partial Class II buildings and projects with special requirements, or ground treatment project that may affect nearby buildings, or ground treatment projects which the ground treatment effect will be showed in the process of civil topside structure construction, or even during the usage, the settlement observation and other monitoring survey shall be arranged during the construction period and the usage. The monitoring survey and detection of the ground treatment shall be in the charge of the Class I exploration and design organizations which are qualified in geotechnical engineering exploration and design.
5.0.14 As for the treated foundation, the foundation bottom area and the embedded depth shall be determined according to the ground bearing capacity. If the characteristic value of subsoil bearing capacity specified in this standard needs be corrected, the correction shall comply with the following the provisions, besides other provisions in the standard:
1 The ground bearing capacity correction coefficient of the foundation width shall be zero;
2 As for the embedded depth of foundation, the ground bearing capacity correction coefficient may be 1.0.
As for the treated foundation, the added part of the bearing capacity may be treated with no depth correction if the ground bearing capacity decreases with the depth increase within the treatment depth range. If the soft-weak subjacent bed is always available in the stressed layer, the ground bearing capacity of the subjacent bed shall be calculated.
As for composite foundation like soilcement mixing pile, the calculation of the pile foundation strength shall be taken out according to the corrected bearing capacity characteristic value of composite foundation.
5.0.15 As for the buildings (structure) which are treated with taken out in accordance with this standard, the checking calculation of the subsoil deformation or the foundation stability shall be taken out in accordance with relative regulations.
5.0.16 Besides the ground treatment methods listed in the standard, other feasible treatment methods such as anchor rod static pressure pile method, root pile method, pit-jacked pile method, single fluid silicification method and alkali liquor method may be adopted in accordance with the geotechnical engineering condition, treatment purpose and applicability, by reference to the relative standards.
6. Replacement Cushion Method
6.1 General Provisions
6.1.1 The replacement cushion method is applicable to the treatments of shallow layer soft-weak or disadvantageous strata. If the soft-weak or disadvantageous strata is thicker, and cannot be treated with full displacement, the substratum shall meet the strength and deformation requirements.
6.1.2 Common cushion materials include, lime soil, granule or grit, crushed stone (pebble), powdered coal ash and so on.
If the materials are stacked, shattered and mixed in the building site, the antipollution measures shall be available.
6.1.3 If drainage consolidation exists in the foundation, drainage cushions should be adopted, but as for the collapsible loess foundation and water softening foundation, the drainage cushions shall not be adopted. If the underground water is of corrosivity, impervious blankets (cushion) should be adopted. If the groundwater velocity is higher, the underground erosion and washing resistance of the cushion material shall be considered.
6.1.4 The thickness z of the cushion (blanket) shall be determined according to the thickness of the displaced soft soil and the substratum bearing capacity. if the soft soil layer is thinner, the soil shall be displaced totally; if the soft soil layer is thicker, the cushion shall meet the requirements of the formula (6.1.4 - 1):
(6.1.4-1)
Where,
——Additional pressure of cushion bottom surface, kPa;
——Self-weight pressure of underlayer base soil, kPa;
——Subsoil bearing capacity characteristic value of cushion bottom s soil layer after depth correction, kPa.
The additional pressures of cushion bottom surface may be calculated simply respectively according to the formula (6.1.4-2) and the formula (6.1.4-3).
Strip foundation:
(6.1.4-2)
Rectangular foundation:
(6.1.4-3)
Where,
——Foundation base width, m;
——Length of rectangular foundation bottom, m;
——Average pressure value of foundation base corresponding to the loading effect standard combination, kPa;
——Self-weight pressure of foundation base soil, kPa;
——Thickness of foundation base underlying cushion, m;
——Pressure diffusion angle of cushion, (°), may be selected form Table 6.1.4.
Foreword
1. Scope
2. Normative References
3. Terms, Definitions and Symbols
3.1 Terms
3.2 Symbols
4. General Provisions
5. General Requirements
6. Replacement Cushion Method
6.1 General Provisions
6.2 Plain Soil Cushion
6.3 Lime Soil Cushion
6.4 Gravel Sand Cushion
6.5 Cushion of powdered coal ash and other industrial slag
7. Preloading Method
7.1 General Provisions
7.2 Surcharge preloading
7.3 Vacuum Preloading
7.4 Deadweight Preloading
8. Heavy-tamping Method
8.1 Heavy-tamping
8.2 Heavy-tamping Displacement
9. Jet Grouting Method
9.1 High Pressure Jet Grouting
9.2 Static Pressure Grouting
10. Vibrofloatation Method
11. Compaction pile method
11.1 General Provisions
11.2 Dry Vibration Pile
11.3 Lime soil and plain soil compaction pile
11.4 Borehole compaction pile
12. Mixing pile method
12.1 General Provisions
12.2 Design
12.3 Construction
12.4 Quality Supervision
13. Geosynthetic Application
13.1 General Provisions
13.2 Materials
13.3 Anti-filtering and drainage
13.4 Antiseepage
13.5 Reinforced cushion and reinforced soil retaining wall
13.6 Filling banks with geotextile bag
14. Pile foundation project
14.1 General provisions
14.2 Filling pile
14.3 Driven pile
14.4 Composite pile foundation controlled by settlement
15 Prototype test
15.1 General provisions
15.2 Integrative pile test
15.3 Prototype test for foundation treatment
15.4 Dynamic test for pile
Appendix A
Appendix B
Appendix C
Appendix D
Appendix E
Appendix F
