| 1. |
- Ahmadi, H., et al.
(författare)
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Experimental Research on Variation of Pore Water Pressure in Constant Rate of Strain Consolidation Test
- 2014
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Ingår i: Acta Geotechnica Slovenica. - 1854-0171. ; 11:2, s. 46-57
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Tidskriftsartikel (refereegranskat)abstract
- Constant rate of strain (CRS) consolidation is a rapid test method which is used for determination of compressibility of clayey soils. In a CRS test, the appropriate strain rate is selected based on pore water pressure ratio, i.e. the ratio of pore pressure to total stress. In the present study, to investigate the effect of strain rate on variation of pore water pressure ratio, four different clay samples of different plasticity were tested by CRS apparatus. The results of the experiments showed that the trend of variation of pore water pressure is dependent on the drained water flow regime which may be either Darcy or non-Darcy. The results also indicated that the plasticity of clay does not have considerable effect on variation of pore water pressure.
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| 2. |
- Alén, Claes, 1949, et al.
(författare)
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Lime/Cement Column Stabilised Soil - A New Model for settlement calculation
- 2005
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Ingår i: Deep Mixing '05.
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Konferensbidrag (refereegranskat)abstract
- A new model for calculation of settlements for an embankment on lime/cement stabilised clay is presented. The model can be regarded as a development of the current Swedish practice, which is based upon a simplified model, adopted in the computer program Limeset. The goal has been to incorporate recent years experience and research in a qualitative and realistic way. The model is based on the assumption that the deformation properties of the natural as well as the stabilised clay can be modelled in a conventional way. Hence, the development is to give a realistic description of the interaction between these two parts of the soil. A notable feature of this is to describe the stress distribution in the soil in a simple, yet relevant way.
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| 3. |
- Alén, Claes, 1949
(författare)
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On Probability in Geotechnics. Random Calculation Models Exemplified on Slope Stability Analysis and Ground-Superstructure Interaction
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The thesis deals with uncertainty in calculation modelling. Emphasis is put on the design state. Design is a chain of decisions under uncertainty. A probabilistic approach is used to describe the uncertainty and calculations as a way to reveal the uncertainty. Thus, a calculation method becomes an operative tool in a risk analysis, not merely a verification of a prescribed minimum level. The work is a combination of elements from three different academic disciplines; geotechnics, structural mechanics and statistics. Different aspects from two fields of geotechnical modelling are discussed; slope stability as an example of ultimate limit state problems, and interaction ground /superstructure as an example of serviceability limit state problems. For the mathematical solution different algorithms are used; mathematical analysis, point estimate method, Monte-Carlo simulation and reliability analysis. Soil properties are described as random variables. Different uncertainties are accounted for; natural variations, systematic testing errors, random testing errors and errors due to limited testing. Pre-knowledge and test results are combined systematically using Bayesian statistics. Three different levels of complexity of both slope stability analysis and ground/superstructure interaction are given. In both cases, structural models of the soil are given for the third level. For a slope a constant degree of mobilisation is not a prerequisite. Instead the deformation properties of the soil are considered. In the interaction analysis the soil is described as a continuous shear beam on elastic supports. The structural model of the soil can be calibrated against a more rigorous geotechnical model. To determine volumetric creep deformations in clay a simple creep model is presented, in which the soil deformations can be determined as a sum of elastic/plastic deformations and creep deformations.
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| 4. |
- Alén, Claes, 1949, et al.
(författare)
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Slitsmurar som permanenta konstruktioner
- 2006
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Slitsmursteknik är internationellt en vanligt förekommande metod. Den användes framförallt vid djupa schakter för källare och infrastrukturkonstruktioner i innerstadsbebyggelse. Ett annat användningsområde är som tätskärm vid dammar eller deponier. När slitsmuren användes vid djupa schakter utnyttjas den normalt också i den permanenta konstruktionen, vilket ökar metodens ekonomiska konkurrenskraft. Vid tät stadsbyggnad har metoden stora fördelar tack vare sin begränsade omgivningspåverkan (buller, damm, deformationer etc) jämfört med spontslagning och sin goda ekonomi när den kan utnyttjas som permanent konstruktion.I Sverige har slitsmurar använts endast vi ett fåtal tillfällen och då endast som temporär konstruktion. De senaste exemplen är Götatunneln i Göteborg och Citytunneln i Malmö.Med ett ökat undermarksbyggande i våra större städer har intresset ökat för att också utnyttja slitsmuren i den permanenta konstruktionen och därigenom öka den ekonomiska nyttan och även ta mindre mark i anspråk under byggandetI avsikt att utreda möjligheten att kunna acceptera slitsmuren i permanenta konstruktioner tog Vägverket under år 2004 initiativet till ett branschgemensamt utvecklingsprojekt med Vägverket, Banverket och SBUF som finansiärer. Projektet skall resultera i en rekommendation om vilka begränsningar och förändringar som erfordras för att kunna utnyttja tekniken . Alternativt skall projektet utmynna i ett motiverat avstyrkande av tekniken. Behov av ytterligare utvecklingsarbete skall också identifierats.För projektets genomförande har en projektgrupp tillsatts representerande expertis inom de olika områden som är relevanta för slitsmurar. En referensgrupp med representerande för myndigheter, utförare , konsulteroch högskolor har sammankallats vid två tillfällen. Enskilda personer i referengruppen har intervjuats i speciella frågeställningar.Efter inledande litteraturstudier och seminarier i samband med en slitsmurskonferens arrangerad av Vägverket och Banverket har arbetet koncentrerats på följande områden:-Slitsmurens beständighet, framför allt frågeställningar beträffande krav på material ochutförande, konstruktiva lösningar samt sprickviddsbegränsninagr -Geotekniska frågeställningar speciellt med koppling till påverkan på slitsmurens täthet, kvalitet och beständighet.-Inverkan av stödvätska på den färdiga slitsmurskonstruktionens egenskaper -Internationella erfarenheter; brukare och entreprenörer har intervjuats om erfarenheter i driftsskedet och under utförandet. Arbetet och analyser har baserat på litteraturstudier, enkätsvar från beställare och entreprenörer, intervjuer med experter och myndigheter samt egna erfarenheter avslitsmursarbeten inom projektgruppen.För utredning av stödvätskans inverkan på den färdiga slitsmuren har fältförsök utfört vid Citytunnelprojektet i Malmö. Projektgruppen finner att man med dagens kunskaper kan rekommendera slitsmurar för permanent bruk under vissa förutsättningar t.ex:-Betongens vct skall vara mindre än 0,50-Vid konstruktioner med miljöbelastning motsvarande vägmiljö samt vid krav på torr inomhusmiljö bör en inre betongvägg utföras innanför slitsmuren.-Sprickvidden i permanentskedet bör inte överstiga 0,2mm. -Möjlighet finns att åstadkomma frostbeständig betong där så erfordras.-Den tillåtna vidhäftningsspänningen mellan betong och armering reduceras med 20 %. Vissa frågeställningar bör belysas ytterligare för att eventuellt kunna öka potential och ekonomi för permanenta slitsmurar t.ex:-Ett mer nyanserat sätt att formulera sprickviddskrav för att på ett relevant sätt kunna hantera vattentäthet, beständighet och omgivningspåverkan både i permanent- och utförandeskedet.-Vidhäftningens beroende av stödvätskan-Storlek av belastningar som användes vid dimensionering av slitsmurar-Påverkan på betongens hållfasthet och täthet av stödvätska, tillsatsmedel och arbetsutförande.-Påverkan av slitsmurens täthet på omgivningen.Viktiga faktorer för att uppnå ett bra kvalitet på den permanenta slitsmuren är bl.a:-Arbetesutförandet och erfarenheten hos slitsmursentreprenören är av avgörande betydelse för en bra kvalitet.-Samverkan mellan projektör, entreprenör och beställare är viktigt för att uppnå ett bra resultat. -Armeringens utformning och detaljlösningar vid anslutande bjälklag bör ägnas speciell omsorg. För tätt armerade konstruktioner i syfte att uppnå täta konstruktioner kan motverka sitt syfte.-Stödvätskans egenskaper och hantering har en avgörande inverkan på slutproduktens kvalitet.
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| 5. |
- Alén, Claes, 1949, et al.
(författare)
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Test Embankments on Lime/Cement Stabilized Clay
- 2005
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Ingår i: Deep Mixing 05.
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Tidskriftsartikel (refereegranskat)abstract
- In a large expansion of the infrastructure in Western Sweden a divided highway and a double railroad track for high speed trains are being planned in the Eastern part of the Göta river valley. Lime/cement columns were considered an attractive method for foundation in many of the cases. In order to improve the accuracy of the settlement calculations, which was considered crucial in the project, four test embankments were constructed. The results from these test embankments are reported in this paper. The embankments, which were constructed in two lifts, about a year and a half apart, were monitored in terms of settlement at the surface as well as at different depths. Measurements were taken in the columns as well as in the clay in between the columns and also below the stabilized soil. A number of piezometers were installed and also a couple of inclinometers. In the paper the overall behaviour of the stabilized soil is analysed and comparison with generally accepted assumptions is made. The results comprise an important base for another paper where a new approach to settlement calculations for lime/cement stabilized soil.
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| 6. |
- Baker, Sadek, et al.
(författare)
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Deformation properties of lime/cement columns. Evaluation from in-situ full scale tests of stabilised clay
- 2005
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Ingår i: Deep Mixing 05.
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Tidskriftsartikel (refereegranskat)abstract
- A realistic evaluation of the deformation properties of lime cement column stabilised soil is of great importance for the accuracy of the calculation of the total and time dependent settlement. It is difficult to determine the in situ compression modulus and the hydraulic conductivity of a lime cement column, and very few methods exist. In this study two different load test methods were used to evaluate the column modulus in situ. They are described in detailed as well as the analytical evaluation of the modulus. The hydraulic conductivity of the lime cement column was measured by using a method called packer test, which is similar to a method used for measurement of hydraulic conductivity in a rock mass. The evaluation of the hydraulic conductivity of the column was obtained using results from the field tests and numerical analysis. A comparison is also made with empirical rules for modulus and hydraulic conductivity recommended for engineering design.
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| 7. |
- Göransson, Gunnel, et al.
(författare)
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A methodology for estimating risks associated with landslides of contaminated soil into rivers
- 2014
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 472, s. 481-495
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Tidskriftsartikel (refereegranskat)abstract
- Urban areas adjacent to surface water are exposed to soil movements such as erosion and slope failures (landslides). A landslide is a potential mechanism for mobilisation and spreading of pollutants. This mechanism is in general not included in environmental risk assessments for contaminated sites, and the consequences associated with contamination in the soil are typically not considered in landslide risk assessments. This study suggests a methodology to estimate the environmental risks associated with landslides in contaminated sites adjacent to rivers. The methodology is probabilistic and allows for datasets with large uncertainties and the use of expert judgements, providing quantitative estimates of probabilities for defined failures. The approach is illustrated by a case study along the river Gota Alv, Sweden, where failures are defined and probabilities for those failures are estimated. Failures are defined from a pollution perspective and in terms of exceeding environmental quality standards (EQSs) and acceptable contaminant loads. Models are then suggested to estimate probabilities of these failures. A landslide analysis is carried out to assess landslide probabilities based on data from a recent landslide risk classification study along the river Gota Alv. The suggested methodology is meant to be a supplement to either landslide risk assessment (LRA) or environmental risk assessment (ERA), providing quantitative estimates of the risks associated with landslide in contaminated sites. The proposed methodology can also act as a basis for communication and discussion, thereby contributing to intersectoral management solutions. From the case study it was found that the defined failures are governed primarily by the probability of a landslide occurring. The overall probabilities for failure are low; however, if a landslide occurs the probabilities of exceeding EQS are high and the probability of having at least a 10% increase in the contamination load within one year is also high.
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| 8. |
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| 9. |
- Olsson, Mats, 1974, et al.
(författare)
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Some experiences from full-scale test embankments founded on floating lime-cement columns
- 2008
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Ingår i: Proc. of the 2nd int. workshop on Geotechnics of soft soils.
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Konferensbidrag (refereegranskat)abstract
- In western part of Sweden 80 km of a new motorway and a new high speed railway will be constructed on soft, high-plastic clay. In order to reduce the settlements and improve the stability conditions of the embankments, lime-cement columns will be used extensively, i.e. some 9 million linear metres of columns will be installed. Already during the feasibility studies, in year 2000, a large amount of test-columns were installed in order to study their geo mechanical properties (strength, stiffness, permeability). Furthermore 3 full-scale test embankments, founded on lime-cement columns not reaching firm bottom were constructed in year 2001. The test embankments were considered necessary due to lack of reliable design methods for estimating consolidation settlements of embankments founded on floating columns. The embankments were heavily instrumented in order to study the settlements of the embankments.
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| 10. |
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