1 General Provisions
1.0.1 This code was formulated to unify the construction specifications of railway subgrade, assure the engineering quality, and make the subgrade construction meet the requirements on safety, applicability, state-of-art technology and economic feasibility.
1.0.2 This code is applicable to the construction and acceptance of the subgrade engineering in the newly-built or reconstructed full gauge railway with the highest running speed of passenger train of 140km/h.
1.0.3 The subgrade engineering must be constructed according to the approved design documents, amendments, if any, shall be in accordance with those specified in the current design change management method of railway design. In the construction, if the actual conditions are discovered different from the design or new engineering issues appear, the related information shall be feed back to the design organization timely.
1.0.4 The railway subgrade shall be constructed meticulously as soil structures; the subgrade construction shall be managed strictly according to the engineering quality standard without left any engineering diseases. All the projects on subgrade shall be completed matching with each other on schedule timely; the relevant data shall be collected timely to formulate into the completion documents.
Technical safety measures shall be reinforced at such important construction site or procedure, and the affects and damages of rain, water, wind, snow and other natural disasters shall be prevented in the construction.
1.0.5 As for concealed works, the construction of the next procedure shall not be started until this work passing the inspection and being transacted with license.
1.0.6 In the subgrade construction, importance shall be attached to the farmland water conservancy and the optimal land and arable land utilization.
1.0.7 The subgrade construction shall comply with the related policies and regulations on environmental protection. And the environmental protection engineering shall be constructed matching with the major project simultaneously as required.
1.0.8 The subgrade construction shall be arranged comprehensively, treated in accordance with local conditions, used with the local materials, planned thoroughly and adopted with accurate construction method, and the construction labor force shall be allocated reasonably.
1.0.9 The major projects shall be formulated with individual practical construction design scheme and shall be constructed based on this design scheme after it being approved according to the established procedures.
1.0.10 The subgrade engineering shall carry out mechanized construction, popularize adoption of new technologies, new processes, new facilities and new test methods, and also shall be formulated with the process requirements that can meet the quality standard as specified in this code so as to improve the technical level and quality of subgrade construction constantly.
1.0.11 The steel products, cement geosynthetic materials, blasting equipments, large-scale machines and detection devices used for the subgrade engineering shall be in accordance with the current relevant standards of the nation and also shall be equipped with the quality certificates, in additions, the equipments shall be set with nameplates.
1.0.12 The road shoulder and side slope of the soil subgrade shall not be buried with any cables or electric poles for construction.
1.0.13 The mechanized operating platform of the newly-built regional subgrade shall be constructed completely along with the subgrade.
1.0.14 As for the reconstruction of existing lines and the additional construction of the second line of subgrades, the construction shall be arranged thoroughly to ensure the safety of existing routes.
1.0.15 The construction o subgrade engineering shall not only comply with this code, but also shall comply with those specified in relevant current national compulsory standards.
2 Terms and Symbols
2.1 Terms
2.1.1 Gap behind abutment of bridge or culvert
Gap behind abutment of bridge: The scope at back bottom of the abutment no less than 2m and above the abutment no less than the abutment height added by 2m.
Gap behind abutment of culvert: The scope at both sides of the culvert, which is no less twice of the pore diameter of culvert but no less than 2m at each side.
2.1.2 Reserved amount of settlement
The height of preplaced filling soil in order to cover the settlement embankment and subgrade after filling the embankment.
2.1.3 Soil materials
Natural soil and rock, including the loosed and cracked soil and stone.
2.1.4 Fill materials
The soil materials used for filling the embankment and replacing the subgrade, including the screened soil materials or those blended machined according to certain requirements.
2.1.5 Permeable soil
The rock mass and coarse-grained soil (excluding silty sand and sticky sand) with the content of fine-grained soil less than 15% as listed in the classification table of fill materials.
2.1.6 Unpermeable soil
The rock mass, coarse-grained soil and easy-to-weather soft soil block stone with the contents of various fine-grained soil and silty sand, sticky sand as well as fine-grained soil being larger than or equal to 15% as listed in the classification table of fill materials.
2.1.7 Improved soil
The soil mass by improving the engineering property through mixing such materials as lime, cement, fly ash and curing agent.
2.2 Symbols
Dr——the relative density
D15——the particle diameter of the fill materials in the coarse particle layer among adjacent filling layers, with the content corresponding to 15% in the grain size distribution curve.
d85——the particle diameter of the fill materials in the fine particle layer among adjacent filling layers, with the content corresponding to 85% in the grain size distribution curve.
Kh——the compacting factor of the heavy compaction standard
K30——the foundation coefficient
n——the porosity
ωopt——the optimum water content of fill materials
[σ]——the allowable bearing capacity of subgrade
ρ——the density of compacted soil and density of wet soil
ρd——the dry density of soil
ρdmax——the maximum dry density of soil
ρ0——the natural density of soil
3 Construction Preparation
3.0.1 Before commencing the construction, the design documents and their contents shall be checked to whether meet the field actual condition in combination of the field investigation.
3.0.2 The examination of the construction of subgrade engineering shall not only include the projects needed jointly by the full line or full section, but also shall cover the research and collection of the following contents of data according to the engineering characteristics, and the investigation report shall be written out.
1 Conditions of special subgrade, including geology, underground water level and frozen depth.
2 Check the categories and distribution of earth material, and preliminarily recheck and test the fill materials. Examine the environmental conditions of the construction of high fill, deep cut and yard, the sources of the fill materials at such sections where are difficult to borrow or abandon soil, the soil abandoning position and the soil hauling conditions.
3 The geography, landscape and geology of the large scale rock blasting section as well as the conditions of the residents, construction works, traffic generation and communication facilities nearby.
4 The transportation and assembly site of large-scale earth and rock construction machine.
5 The data needed in all temporary works and construction waterproof and drainage.
6 The transport operation condition, subgrade condition of the existing line as well as the data needed for adopting safe, reasonable and convenient engineering measures.
7 The data on such special needs as new technologies, new processes, new equipments and new materials.
3.0.3 Piles shall be connected on the spot and the relevant handing over procedures in written form shall be transacted.
3.0.4 The center line, level and border piles of the remeasured route shall meet the following requirements:
1 The center line and level of remeasured route must be connected and closed with the center line and level of the adjacent work section.
2 The measurement result at every time must be rechecked. The original measuring records shall be stored integrally till after the acceptance survey is completed.
3 The principal center line control piles shall be set with guard piles and the relevant records shall be done well.
4 The border piles of subgrade shall be set by measuring according to the detail cross section design drawing based on the center line and level after repetition measurement; and the cross section and border piles shall be measured in addition at such parts where geography or geology varies.
3.0.5 Before the construction of subgrade engineering, according to the design document and the construction survey data, the practical construction design shall be compiled according to the requirements of construction period, the construction scheme shall be determined, the feasible safety and environmental protection measures shall be brought forward, the manpower, materials and machines shall be reasonably organized and distributed.
3.0.6 Before the construction of subgrade engineering, a field laboratory and a sound safety and quality assurance system shall be organized.
3.0.7 Before starting the construction, the railway land and the relocation, compensation and other works of facilities in boundary shall be done well.
If there are road, grade crossing, water channel, pipeline, route, cultural relic, permanent measurement stake, geologic or seismologic observation facility within the influence circle of construction are need to be dismounted, rerouted, transferred or protected, the dismounting, rerouting, transferring or protecting works shall be handled properly through the negotiation with the relevant competent departments.
1 General Provisions
2 Terms and Symbols
2.1 Terms
2.2 Symbols
3 Construction Preparation
4 Embankment
4.1 General Provisions
4.2 Bed
4.3 Embankment under Bed
4.4 Subgrade Surface Treatment
4.5 Soil Borrow
4.6 Reserved Amount of Settlement and Observation
4.7 Improved Soil Construction
4.8 Low-temperature Construction
4.9 Rainy Season Construction
4.10 Construction Control and Inspection construction control
5 Road Cuts
5.1 General Provisions
5.2 Parts of Road Cuts
5.3 Waste
6 Subgrade Protection
6.1 General Provisions
6.2 Slope Protection
6.3 Scour Protection
7 Special Subgrades
7.1 Soft Soil Subgrade
7.2 Expansive Soil (Rock) Subgrade
7.3 Loess Subgrade
7.4 Salty Soil Subgrade
7.5 Frozen Soil Subgrade
7.6 Vibration Liquefied Soil Subgrade
7.7 Submerged and Reservoir Subgrades
7.8 Subgrade in Landslide Zone
7.9 Subgrade in Collapse, Rockfall and Rock Pile Zone
7.10 Subgrade in Karst and Cavity Zone
7.11 Subgrade in Windy and Sand Zone
7.12 Subgrade in Snow Damage Zone
8 Retaining Structure
8.1 General Provisions
8.2 Gravity Retaining Wall
8.3 Retaining Wall with Short Relieving Plate
8.4 Cantilever and Counterfort Retaining Walls
8.5 Anchored Retaining Wall
8.6 Anchor-plate Retaining Wall
8.7 Reinforced Earth Retaining Wall
8.8 Soil Nailing Wall
8.9 Friction Pile
8.10 Pile-plate Retaining Wall
8.11 Prestressed Anchor Rope
9 Mechanical Construction
9.1 General Provisions
9.2 Digging and Loading with Excavator
9.3 Digging and Loading with Loader
9.4 Pushing and Transporting with Bulldozer
9.5 Shoveling and Transporting with Earthscraper
9.6 Car Earthmoving
9.7 Train Earthmoving
9.8 Levelingup with Grader
9.9 Mechanical Compaction
10 Blasting
10.1 General Provisions
10.2 Common Blasting
10.3 Smooth Blasting and Presplitting Blasting
11 Engineering Acceptance
Appendix A Placement and Compaction Test of Embankment
Appendix B Classification, Outdoor Identification and Indoor Test of Fill Materials
Appendix C Classification of Rock-soil Construction Works
Appendix D Explosive Specific Charge k for Blasting Various Rocks
Explanation of Wording in this Code
