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Radiation is a process by which energy moves through a medium or vacuum without the movement of any molecules and without heating any medium through which it passes. The quantity of energy radiated from a grain surface increases with increased surface temperature and neighbouring grains increase their temperature by absorb­ing the radiation emitted. Because the […]

The basic principles to model the complete time-dependent heat transfer in soils are described in this section. More details of these and the associated effects can be found in some of the better or more specialist geotechnical textbooks, for example Mitchell and Soga (2005) or Fredlund and Rahardjo (1993). The water content in various road […]

Ake Hermansson[6], Robert Charlier, Frederic Collin, SigurSur Erlingsson, Lyesse Laloui and Mate Srsen Abstract Temperature highly affects pavement performance. High and low tem­peratures not only affects the viscosity of asphalt concrete but also has an impact on the moisture flow within pavements. At temperatures below 0°C the freezing of pavements dramatically changes the permeability and […]

Although far less common than in the laboratory, techniques for in-situ matric suc­tion measurements using the contact filter paper (CFP) method and in-situ total suction measurements using the non-contact filter paper method have also been described (Greacen et al., 1989). The filter paper technique is, in theory, applicable over the entire range of total suction, […]

A simple laboratory variant of the tensiometer method for measuring matric suction of fine-grained soils uses a semi-pervious sintered glass plate. A small soil sample Fig. 3.15 Comparison between laboratory soil suction measurements with tensiometers and TCS. Reproduced with permission of D. Fredlund is placed on the glass plate and covered immediately with a cap […]

Thermal conductivity sensors (TCS) are used to indirectly relate matric suction to the thermal conductivity of a porous medium embedded in a mass of unsaturated soil. Any change in the soil suction results in a corresponding change in the water content of the porous medium (governed by its characteristic curve). The thermal conductivity of a […]

One of the most common devices for measuring suction is a tensiometer. A ten­siometer consists of a fine porous ceramic cup connected by a tube to a vacuum Technique/Sensor Suction component measured Measurement range (kPa) Equilibrium time Laboratory/Field Tensiometers Matric 0-100 Several minutes Laboratory and field Axis translation techniques Matric 0-1500 Several hours-days Laboratory Electrical/ […]

Soil suction or capillary pressure head can be measured either in the laboratory in an undisturbed sample of soil or directly in the field. Soil suction or total suc­tion consists of the matric suction and the osmotic suction. Their magnitudes can range from 0 to 1 GPa (Rahardjo & Leong, 2006). Today no single instrument […]

As introduced in Chapter 2, the flow of water in saturated soils is commonly de­scribed using Darcy’s law which relates the rate of water flow to the hydraulic gra­dient (Eq. 2.16). Furthermore the coefficient of permeability is relatively constant for a specific soil. Darcy’s law applies also to the flow of water through unsaturated soils. […]

Tracer tests involve the injection of an inert solution, or tracer, into an existing flow field via a borehole or a well. Tracer tests are often desirable because they are passive-type tests and do not place unnatural stress conditions on the flow system. The dilution rate of the tracer at the injection well or its […]