If no other stipulations are explicitly made in the individual Recommendations, they shall apply under the following engineering preconditions:
1. The complete height of the retaining wall is lined.
2. The soldier piles of soldier pile walls are installed such that intimate contact with the ground is ensured. The lining or infilling can consist of wood, concrete, steel, hardened cement-bentonite suspension or stabilised soil. It shall be installed such that the contact with the soil is as uniform as possible. Soil excavation should not advance considerably faster than plank installation. Also see DIN 4124.
3. Sheet pile walls and trench sheet piles are installed such that intimate contact with the ground is ensured. Toe reinforcement is permitted.
4. In-situ concrete walls are executed as diaphragm walls or as bored pile walls. Accidental or planned spacing between the piles is generally lined according to Paragraph 2.
5. In the horizontal projection, struts or anchors are arranged perpendicular to the retaining wall. They are wedged or prestressed such that contact by traction with the retaining wall is guaranteed.
6. Braced excavations are lined in the same manner on both sides with vertical soldier pile walls, sheet pile walls or in-situ concrete walls. The struts are arranged horizontally. The ground on both sides of the braced excavation displays approximately the same height, similar surface features and similar subsurface properties.
If these preconditions are not fulfilled, or those in the individual Recommendations, and no Recommendations are available for such special cases, this does not exclude application of the remaining Recommendations. However, the consequences of any deviations shall be investigated and taken into consideration.
1. Following its introduction, geotechnical analysis and design in Germany are controlled by DIN EN 1997-1: Eurocode 7: Geotechnical Design – Part 1: General Rules (Eurocode 7), in conjunction with the corresponding National Annex:
– DIN EN 1997-1/NA: National Annex – Nationally Determined Parameters – Eurocode 7: Geotechnical design – Part 1: General rules and
– DIN 1054: Subsoil – Verification of the Safety of Earthworks and Foundations – Supplementary Rules to DIN EN 1997-1.
These three coordinated standards are summarised in the ‘Handbuch Eurocode 7, Band 1’.
The National Annex represents a formal link between the Eurocode EC 7-1 and national standards. It states which of the possible analysis methods and partial safety factors are applicable in the respective national domains. Remarks, clarifications or supplements to Eurocode EC 7-1 are not permitted. However, the applicable, complementary national codes may be given. The complementary national codes may not contradict Eurocode EC 7-1. Moreover, the National Annex may not repeat information already given in Eurocode EC 7-1.
2. In addition, the following Eurocode programme standards govern excavation structures:
| EN 1990 Eurocode 0: | Basis of structural design |
| EN 1991 Eurocode 1: | Actions on structures |
| EN 1992 Eurocode 2: | Design of concrete structures |
| EN 1993 Eurocode 3: | Design of steel structures |
| EN 1995 Eurocode 5: | Design of timber structures |
| EN 1998 Eurocode 8: | Design of structures for earthquake resistance |
3. The Eurocode 7 Handbook, Volume 1 contains general rules for geotechnical engineering. It is supplemented by the analysis standards which, where necessary, have been adapted to the partial safety factor approach. The following codes in particular also represent the governing standards for excavation structures:
| DIN 4084: | Global stability analyses |
| DIN 4085: | Subsoil – Calculation of earth pressure |
| DIN 4126: | Cast-in-situ concrete diaphragm walls; design and construction |
| DIN 4093: | Design of ground improvement – Jet grouting, deep mixing or grouting |
4. The standards covering ground exploration, investigation and description are not affected by the adaptation to partial safety factors and therefore remain valid in their respective latest editions, or are superseded by Eurocode 7 and EN ISO standards:
EN 1997-2, Eurocode 7: Geotechnical design – Part 2: Ground investigation and testing
EN 1997-2/NA: National Annex – Nationally Determined Parameters – Eurocode 7, Part 2: Ground investigation and testing
DIN 4020: Geotechnical investigations for civil engineering purposes – Supplementary rules to DIN EN 1997-2
DIN 4023: Geotechnical investigation and testing – Graphical presentation of logs of boreholes, trial pits, shafts and adits
EN ISO 22475-1: Geotechnical investigation and testing – Sampling by drilling and excavation and groundwater measurements – Part 1: Technical principles for execution, supersedes DIN 4021 and DIN 4022
EN ISO 14688-1: Geotechnical Investigation and testing – Identification and classification of soil – Part 1: Identification and description, superseded by DIN 4022-1
EN ISO 14688-2: Geotechnical Investigation and testing – Identification and classification of soil – Part 2: Principles for classification, superseded by DIN 4022-1
EN ISO 14689-1: Geotechnical Investigation and testing – Identification and classification of rock – Part 1: Identification and description, superseded by DIN 4022-1
EN ISO 22476-2: Dynamic probing
EN ISO 22476-3: Standard Penetration Test
DIN 4094-2: Subsoil – Field testing – Part 2: Borehole dynamic probing
DIN 18121 to DIN 18137: Investigation of soil samples
DIN 18196: Soil classification for civil engineering purposes
DIN 1055-2: Soil properties
5. The Eurocode 7 Handbook, Volume 1, only replaces the analysis section of the previous standards DIN 4014 “Bored piles”, DIN 4026 “Driven piles”, DIN 4125 “Ground anchorages – Design, construction and testing” and DIN 4128 “Grouted piles (in-situ concrete and composite piles) with small diameter”. The new European standards from the “Execution of special geotechnical works” series now take the place of the execution sections of these standards:
| EN 12063: | Sheet pile walls |
| EN 12699: | Displacement piles |
| EN 12794: | Precast concrete – foundation piles |
6. The following execution standards are not affected by the adaptation to European standards and therefore continue to govern excavation structures:
| DIN 4095: | Drainage systems protecting structures |
| DIN 4123: | Excavations, foundations and underpinnings in the area of existing buildings |
| DIN 4124: | Excavations and trenches |
1. In contrast to the original probabilistic safety factor approach, this safety factor approach, upon which both the new European standards generation and the new national standards generation are based, no longer rests on probability theory investigations, e.g. the beta-method, but on a pragmatic splitting of the previously utilised global safety factors into partial safety factors for actions or effects and partial safety factors for resistances.
2. The foundation for stability analyses is represented by the characteristic or representative values for actions and resistances. The characteristic value is a value with an assumed probability which is not exceeded or fallen short of during the reference period, taking the lifetime or the corresponding design situation of the civil engineering structure into consideration; it is characterised by the index “k”. Characteristic values are generally specified based on testing, measurements, analyses or empiricism.
Variable actions can also be given as representative values, thus taking into consideration that not all variable, unfavourable actions occur simultaneously at their maximum values.
3. If the bearing capacity in a given cross-section of the retaining wall or in an interface between the retaining wall and the subsoil needs to be analysed, the effects in these sections are required:
– as action effects, e.g. axial force, shear force, bending moment;
– as stresses, e.g. compression, tension, bending stress, shear stress or equivalent stress.
In addition, further effects of actions may...
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