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In this book, the term Trenchless Technology for Installation of Cables and Pipelines is understood to include the installation of supply and disposal lines (product lines), casing and host pipes, utility ducts and structural shells of man-accessible utility tunnels [Stein02] - all installed using trenchless methods of construction, e.g. without the excavation of trenches. The open cut method cannot be completely avoided but is used only to a limited … |
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(Image: Scientific disciplines of geotechnology with reference to [Floss00] [Image: S&P GmbH]) Geotechnology is a branch of civil engineering concerned with soil or rock as a subsoil and structural material and with the means for investigating its condition and structural utility for construction of stable and functional structures [Schmi96]. The following scientific disciplines, among others, belong to the Geotechnology subject area (Bild 4.1) [Schmi96] : |
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The crust of the earth consists mostly of rock materials that are made up of naturally formed quantities of different minerals (mineral aggregates) or of only one mineral type. This can occur as soil or as rock and sometimes of both in sequence. Soil occurs through the weathering of rock. It exists either in original strata (weathered soils) or has been transported by wind, water or ice and deposited (sediments) (Abschnitt 4.5.1) [Soos96]. Rock is … |
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With non-cohesive soils, the individual particles or parts of the rock material form an agglomeration that possesses a measure of strength due to the friction of the particle surfaces. Their properties are influenced by the particles size, particle size distribution, particle form and particle roughness. Depending on the base material, they are often resistant to weather conditions. According to DIN 1054 [DIN1054:2005], the non-cohesive soils comprise … |
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With cohesive soils, the particles adhere to each other due to electrostatic surface forces and thus form an interconnected formable mass. Their properties (strength behaviour) are influenced largely by the water content, the particle size and the clay mineral content (Abschnitt 4.3.1.5). They are sensitive to weathering. According to DIN 1054 [DIN1054:2005], this type of soil comprises clays, clayey silts, and silts (e.g. sandy clay, sandy silt, … |
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According to DIN 1054 [DIN1054:2005], this type of soil comprises peat or sapropel and inorganic soils with organic admixtures of animal or plant origin (Tabelle 4.3.1.1.3), when the weight percentage is more than 3% or 5% (e.g. sand containing humus, sapropel, or sand containing peat, organic silt or clay, loam). Depending on the degree of decay, such soils possess a fibrous, fleecy or earthy texture and a high degree of water retention or water … |
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Also, according to ISO14688-1 [DINENISO14688:2004], volcanic soils are understood to be, "pyroplastic materials produced and formed by explosive volcanic eruption; e.g. pumice, scoria, volcanic ash." The particles of volcanic soils are generally blistered and the compactness or density of the strata (Abschnitt 4.3.1.4) is relatively low. The soils possess a characteristic colour that depends on the original magma or rock. The main components of … |
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With fine soils, the shape of the particle is solely dependent on the type of the mineral. Quartz, lime and dolomite are generally cubic, clay minerals generally flat and halloysite is longitudinal (elongated). With coarse soils, the particle shape and the roughness is dependent on the type of rock material as well as the transport and weathering history. Increasing transport distances leads to rounding of the edges and the smoothing of the particle. … |
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(Image: Flow chart for the identification and description of soils based on ISO 14688-1 [DINENISO14688a]) The primary differentiating feature of mineral soils is the size of the individual particles. This determination is the first step in the identification and classification of a soil type (Bild 4.3.1.3). A review of the identification of the type of soil with reference to particle size is shown in Tabelle 4.3.1.3. (Table: Identification and particle … |
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Density is used to describe the compactness by which the individual soil particles have arranged or chained. From this, direct assumptions can be made concerning the soil strength, the additional compaction or displacement capability or the water … |
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Cohesive soils change their state or condition with water content. With a very high water content, cohesive soils are liquid and, with reduction of water content, change from a liquid to a plastic state, then to a stiff and finally into a very stiff (hard) condition, which means that the soil is less deformable and its strength increases. The transitions from one condition to the other have been defined by Atterberg [Atter11] and are called consistency … |
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The determination of the uniaxial compressive strength qu of soils, also known as cylinder compressive strength is carried out according to DIN 18136 [DIN18136:2003] on cylindrical or prismatic test bodies at constant compression velocity and with unhindered side expansion. The uniaxial compressive strength is also used in the description of the condition of cohesive soils (Abschnitt 4.3.1.5) [Kezdi68] [Lambe69]. A proposal in this respect for clays … |
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(Image: Soil element under shear loading [Schmi96]) Soil is a structure made up of a framework of solid particles with water and air-filled pores and is therefore sensitive to shear loads that are caused by shear stresses (Bild 4.3.1.7). The fact that a borehole, an excavated cavity in the subsoil, or the working face is stable without supports is a result of the shear strength τ of the subsoil. For instance, this shear strength is lowest for dry sand … |
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Nov 28, 2006 Trenchless Technology for Installation of Cables and Pipelines Mechanical fundamentals of soil and rock (geotechnical parameters) (Image: Flow chart for the identification and description of soils based on ISO 14688-1 [DINENISO14688a]) Soil is a mixture of minerals and/or organic components without mineral cohesion. Separation of the mineral components according to particle size by means of simple sieving or sedimentation process is possible. A further characteristic is the importance of point contacts among the mineral particles. Basically, soils consist of several phases:
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A large zone of rock (rock mass) is not a monolithic body but is more or less divided by discontinuities [DS853]. Their spatial arrangement in the rock mass is called the geologic structure (Tabelle 4.3.2.1) [DINENISO14689:2004]. (Table: Examples of terms which may be used in the description of rock mass structure to ISO14689 [DINENISO14689a])
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As the measured compressive strength of a body can vary depending on the standards of the testing, the determination of the uniaxial compressive strength (UCS) of rock material should be carried out in Germany on the basis of an uniaxial compression test in accordance with DIN 18316 [DIN18136:2003] and the recommendations No. 1 of the Deutsche Gesellschaft für Erd- und Grundbau (DGEG), now called the Deutsche Gesellschaft für Geotechnik (DGGT) [… |
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Nov 28, 2006 Trenchless Technology for Installation of Cables and Pipelines Mechanical fundamentals of soil and rock (geotechnical parameters) ISO 14689 [DINENISO14689:2004] defines rock as, "a naturally occurring assemblage of minerals, consolidated, cemented or otherwise bonded together, so as to form material of generally greater strength or rigidity than soils". Rock material, according to ISO 14689 [DINENISO14689:2004] is, "the intact rock within the framework of the discontinuities." There are intermediate stages between solid and loose sediments. When testing solid rock and rock bond … |
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Nov 28, 2006 Trenchless Technology for Installation of Cables and Pipelines Mechanical fundamentals of soil and rock (geotechnical parameters) According to DIN 1054 [DIN1054:2005] a soil is termed, "made when it has originated due to filling or hydraulic filling". This is divided into:
Embankments, railway banks, waste dumps (landfills) as well as most of the surface regions under … |
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Nov 28, 2006 Trenchless Technology for Installation of Cables and Pipelines Mechanical fundamentals of soil and rock (geotechnical parameters) The following different soil characteristic and calculation values are of great importance for trenchless installation, for instance, in the determination of the required jacking forces, in structural calculations of jacking pipes and shafts, in the determination of soil deformation as well as in the estimation of the stability of the working face (Abschnitt 14) (Abschnitt 15.1). When no soil characteristics from field and laboratory tests are available, … |
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The DIN 18196 [DIN18196:1988] [DIN18196:2004] arranges the types of soil into soil groups only according to the material composition and independent of the water content and density of the soil. The following serve as classification characteristics [DIN18196:1988] [DIN18196:2004] :
For classification purposes, a soil sample must be allocated according … |
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In DIN 18300 "Contract procedures for building works - Part C: General technical specifications for building works; Earthworks" (ATV) [DIN18300-Cd], the subsoil is divided into seven soil and rock classes. The classification characteristic here is exclusively from the point of view of the ease of breakout (Tabelle 4.3.5.2). (Table: Soil and rock classes to DIN 18300 [DIN18300-Cd]) This soil and rock classification is not applicable for boring, drilling … |
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The soil and rock classes, for trenchless technology for installation of prefabricated pipes of any profile by means of pressing-in, pushing-in, ramming-in or pulling-in, [DIN18319:2000] (Bild 4.3.5.3) (Abschnitt 3.1) is defined in the Federal Republic … |
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The Unified Soil Classification System (USCS) of the ASTM (American Society for Testing Materials) Standard D2487-00 "Standard Classification of Soil for Engineering Purposes" [ASTMD248700] of the USA, divides soil into 15 classes (Tabelle 4.3.5.4) which are always described by a group symbol that comprises two characteristic letters [Weiß96b]. (Table: Soil classification according to the USCS (USA) [ASTMD248700]) Five letter symbols represent the … |
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(Image: Procedure for maesurement and calculation of RQD-value [Hoek95]) The Rock Quality Index (abbreviated to RQD-value or RQD-index) was developed in 1967 by Deere [Deere67] as a characteristic for describing rock and relies on the length of the intact segments of the bore core to designate the quality of the rock mass. The RQD-value provides the relationship L10/L in percent where L10 is the cumulative length of core pieces with intact length of … |
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