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(Image: Attention!) The results of the geotechnical investigation as well as the laboratory analyses must be determined accurately by the geotechnical specialist or engineering geologist and described in a geotechnical report. Geotechnical reports, also referred to as subsoil reports or expertise, are intended to inform the client and contractor about the most important properties and characteristic parameters of the subsoil. |
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(Image: Documentation) |
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(Image: Documentation) In trenchless installation, the geotechnical report should at least contain the following points [DIN18319:2000] [Scher99a] [GSTT5] [DCA01] [DINEN12889:2000]:
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(Image: Documentation) For soil, the geotechnical report must include the following points in addition:
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(Image: Documentation) For rock, the geotechnical report must include the following points in addition:
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Soil is called backfill if it "has been artificially placed." Backfill is divided into:
[DIN1054:2010], [[ASTM D2321–05]] (Image: Compacted backfill under a motorway) Most of the areas below the surface of traffic ways and |
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The following categories will be used for a more detailed description: (Image: Unconsolidated soil categories) |
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The main types of soil are:
[[EN ISO 14688:2002]] differentiates
These main soil types consists of
These are further differentiated using particle fractions. |
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By non-cohesive soil, the individual mineral or rock grains form a loose cluster as a result of frictional forces that occur when the grain surfaces rub against each other. The characteristics of non-cohesive soil are influenced by the following parameters:
(Image: Non-cohesive soil particles, held loosely together through the grain surface friction) Sands, gravels, stones, and their … |
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In the case of cohesive soil, the particles cling together as a result of electrostatic surface forces, forming a bonded and mouldable mass. Its characteristics (strength) are essentially influenced by the following parameters:
This type of soil is sensitive to weather conditions. It includes clays, clayey silts (e.g., sandy clay, sandy silt, loam, marl), as well as their mixtures with non-cohesive … |
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The soil is classified as organic silt or organic clay if the liquid limit after oven drying is less than 75% of the liquid limit of the original specimen determined before oven drying. A further classification of organic fine-grained soils (group symbols OL and OH) is presented in a future section [[ASTM D2487-06]]. Another organic soil type is peat, which consists of "primarily vegetable tissue in various stages of decomposition, usually with an |
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The (top) soil in a narrow sense is defined as the most biologically active part of the top crust of the earth, which is surrounded by rock or soil below, and by vegetation or atmosphere above [MURL1991]. The soil can be classified, based on its percent by mass, into organic soil and mineral soil with an organic percentage [DINENISO14688:2018] [DINENISO14688:2018]. (Image: Topsoil) (Table: Classification of soil with organic percentages according to … |
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According to [DINENISO14688:2018], volcanic soil is defined as “magma that has been emitted into the atmosphere during intense volcanic eruptions and, over time, has formed deposits; e.g., pumice, scoria, ash.” (Table: Designation and description of volcanic types of soil [ENISO14688]) |
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Fine soil particle shape depends solely on the type of mineral.
Coarse soil particle shape and roughness depend on the type of rock as well as the individual history of transportation and weathering.
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The grain particle shape has an influence on the texture and isotropy of the soil, as well as on the structural characteristics of the subsoil, such as:
[Soos96] [Trian00]. (Image: Particle shape - well rounded) (Image: Particle shape - Rounded) (Image: Particle shape - Sub rounded) (Image: Particle shape - Angular) (Image: Particle shape - Very angular) |
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The primary distinctive feature of mineral soil is the grain size of the individual particles. The determination of the grain size is the first step in the designation and classification process of a certain type of soil. (Image: Soil grain sizes from 0 – 4 mm) (Image: Soil grain sizes from 4 – 25 mm) |
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An important factor in soil classification presented in the upcoming pages is the soil particle size (grain size). Two scales are used for classification purposes of soil grain size:
The table below presents the most common sieve mesh opening sizes for these two scales. (Table: US sieve mesh size) |
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The cumulative frequency polygon of the mass percentages of the given soil sample is called a grading curve (or grain size curve), and is used for a definite designation of the soil. (Image: Grading curves of some characteristic types of soil [Neuma64]) |
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