Rolf Sandven

Determination of the Transitional Fines Content of Mixtures of Sand and Non-Plastic Fines

Sand-silt mixtures show different behavior with different fines content. The transitional fines content (TFC) is a key parameter which can indicate if the soil behaves as a sand-dominated or as a fines-dominated material. The determination of the TFC for a sand-silt mixture and the possible ways of obtaining the TFC from index data and the triaxial test results are discussed in this study.

Influence of water and fat content on compressive stiffness properties of impacted morsellized bone: An experimental ex vivo study on bone pellets

Background The initial stability of an exchanged hip arthroplasty is crucial for the survival of the revised joint. Several factors can affect the outcome. The amount of liquid in morsellized bone has a major influence on the constrained stiffness properties of impacted bone applied in revision joint surgery. Method To determine whether water or fat is the main contributing liquid, we performed an experimental study on impacted morsellized cortico-cancellous bovine bone to compare the constrained e-moduli in native bone and bone with modified water and fat content. The bone was impacted into bone pellets by a standardized method by which the construction procedure was monitored. Other stiffness properties were recorded during subsequent load testing. Results Low water content significantly increased the constrained stiffness moduli during load, while high water content significantly reduced it. Low fat content increased stiffness significantly only during the initial phase of loading. Interpretation Our findings indicate that the preparation and usage of morsellized bone in revision joint surgery should be performed under dry conditions to improve the initial stability of the revised prosthesis. ▪

Runout of Landslides in Sensitive Clays

An essential part of landslide hazard and risk assessment is the estimate of the runout distance of the landslide masses. There is, however, little guidance available today on the estimation of the landslide runout in sensitive clays and no suitable model exists for predicting runout in sensitive clays. A new empirical model for the runout estimation is presented in this paper. The new model is based on empirical data, and is recommended for use in Norway until further research on analytical models becomes available. The recommended empirical procedure is based on the historical landslides in sensitive clays in Norway. The paper discusses the implementation of the proposed empirical models in a calculation tool called GeoSuite Toolbox as a part an ongoing R&D project GeoFuture II.

CPTU Classification Diagrams for Identification of Sensitive Clays

When dealing with slope stability considerations in deposits where sensitive and quick clays might be encountered it is vital to map the extent of these clays. For the geotechnical engineer, the cone penetration test with pore pressure measurement (CPTU) is a powerful tool in this respect. With its combined measurement of tip resistance, pore pressure and sleeve friction, the CPTU holds a great potential for identification of quick and sensitive clays. Such interpretations can be done based on measured data directly or by combining parameters in dimensionless numbers. Amongst the more popular dimensionless numbers are the pore pressure ratio (B q ), the cone resistance number (N m ) and the friction ratio (R f ). Diagrams exist which allow classification of soils based on the combination of such numbers. Robertson (Can Geotech J 27:151–158, 1990) is one widely used example. However, In Norway, it is found that existing diagrams to a large extent fail to identify sensitive and quick clays. Based on a database of 10 Norwegian sites a new set of classification diagrams are presented with focus on identifying quick and sensitive clays. The diagrams are based on a pore pressure ratio where the tip pore pressure is used (u 1 ) rather than the u 2 -position as this is found to better capture the actual collapsible response of sensitive clays. The cone resistance number is modified to also include an effect of overconsolidation (OCR) instead of only accounting for vertical effective overburden. Also, the friction ratio is normalized with pore pressure (u 1 ) rather than the cone resistance. Electrical resistivity values from R-CPTU-soundings are also included in the considerations. The outcome is a set of revised classification diagrams that provides more accurate identification of Norwegian sensitive and quick clays compared to existing classification diagrams.

Future Strategy for Soil Investigations in Quick Clay Areas

The landslides at Rissa in 1978, and more recently at the Skjeggestad bridge in Norway, are devastating reminders of the potential threats related to quick clays. For a geotechnical engineering project it is hence important to determine if there is sensitive clay present and to clarify the extent of the quick clay deposit. Integration of geophysical and geotechnical methods has become more common in ground investigations nowadays, particularly in larger projects. In such integrated measurements, geotechnical engineers and geophysicists can cooperate, and by joint knowledge decide where geotechnical soundings, in situ tests and sampling should be located with optimal cost-efficiency. This paper describes how various investigation methods may be combined to achieve a successful strategy for detecting deposits of quick and sensitive clays. The methods presented herein include conventional soundings, CPTU and field vane test (FVT), supplemented by geophysical methods such as CPTU with resistivity measurements (R-CPTU), Electrical Resistivity Tomography (ERT) and Airborne Electromagnetic Measurements (AEM).

Geotechnical Evaluation of a Quick Clay Area in Trondheim, Norway

In geotechnical engineering, the presence of sensitive clays poses a major challenge. The landslides at Rissa in 1978, and more recently at the Skjeggestad bridge in Norway, are reminders of the potential devastating threats related to such soils. Norway has several sets of regulations to handle construction work in sensitive soils. This paper exemplifies the implementation of the regulations for a densely populated area on a quick clay area. The city area of Trondheim in central Norway has several zones of quick and sensitive clays which cause severe challenges for urban planning and development. One of these areas is the Gloshaugen – Bakklandet quick clay zone. The project partners consulted the company Multiconsult ASA to undertake the geotechnical evaluation of the area in the period 2012–2014. This work helped assessing areas where special geotechnical investigations and evaluations must be carried out to allow further development of infrastructure and erection of new buildings. The results from this work have been further developed into hazard maps, revealing several major deposits of quick clay within the quick clay zone. The results may be used as a basis for general planning by the local authorities, but are particularly helpful as a background for further development of the NTNU university campus at Gloshaugen.