Geotechnical engineering is strongly associated with large uncertainties. Exploring a medium (soil) that is almost entirely and completely hidden from us is no easy task. Investigations can be made only at discrete points, and the majority of a specific soil volume is never tested. All soils experience inherent spatial variability, which contributes to some uncertainty in the design process of a geotechnical structure. Furthermore, uncertainties also arise during testing and when design properties are inferred from these tests. To master the art of making decisions in the presence of uncertainties, probabilistic description of soil properties and reliability-based design play vital roles. Historically, the observational method (sometimes referred to as the “learn-as-you-go-approach”), sprung from ideas by Karl Terzaghi and later formulated by Ralph Peck, has been used in projects where the uncertainties are large and difficult to assess. The design approach is still highly suitable for numerous situations and is defined in Eurocode 7 for geotechnical design. In paper I, the Eurocode definition of the observational method is discussed. This paper concluded that further work in the probabilistic description of soil properties is highly needed, and, by extension, reliability-based design should be used in conjunction with the observational method. Although great progress has been made in the field of reliability-based design during the past decade, few geotechnical engineers are familiar with probabilistic approaches to design. In papers II and III, aspects of probabilistic descriptions of soil properties and reliability-based design are discussed. The connection between performing qualitative investigations and potential design savings is discussed in paper III. In the paper, uncertainties are assessed for two sets of investigations, one consisting of more qualitative investigations and hence with less uncertainty. A simplified Bayesian updating technique, referred to as “the multivariate approach”, is used to cross-validate data to reduce the evaluated total uncertainty. Furthermore, reliability-based design was used to compare the two sets of investigations with the calculated penetration depth for a sheet-pile wall. The study is a great example of how a small amount of both time and money (in the pre-investigation phase) can potentially lead to greater savings in the final design. / <p>QC 20160201</p> / TRUST, Transparent Underground Structures

A model study on laterally braced sheet pile walls retaining cohesionless soil was conducted using 1-g shaking table. Lateral dynamic earth pressures, backfill accelerations and dynamic displacement of walls were measured. Input accelerations were kept between 0.03g to 0.27g. A data acquisition system consisting of dynamic pressure transducers, accelerometers, displacement transducer, signal conditioning board and a data acquisition card compatible with a personal computer was used during the study. Three different walls with thicknesses of 6.6, 3.2 and 2.0 mm were used in order to investigate the effects of changing wall stiffness value on lateral seismic pressures developed on the wall. In addition to that, steel blocks were placed on top of the backfill in order to simulate a surcharge effect of 1.57 kPa to 3.14 kPa during shaking. Amplification of input acceleration, incremental seismic lateral thrusts and corresponding maximum dynamic pressures, application point of the resultant, effect of stiffness and surcharge on maximum seismic lateral thrust and dynamic wall deflections were calculated by processing raw data stored. The results were compared to previous model studies and some analytical methods available.

The thesis is focused on the reconnstruction of the "Old Bridge“ in Bratislava. Part of the reconstruction is the foundations of a new pier and redevelopment of an existing pier. The introduction provides an overview of methods used for the foundations within the river and from there onwards, the most suitable method haas been selected. The piers foundation is designed in several variants, coupled with the drawings. In conclusion, the variants were compared and the most suitable one was selected.

Målet med rapporten är att redovisa erforderliga maskiner, personal och erfarenhetsdata för sekantpålning. Detta kan utnyttjas vid jämförelse med andra pålningsmetoder av företag.   Sekantpålning används som en stödkonstruktion, vars uppgift är att stötta jordmassor vid schakt. De positiva egenskaperna med denna är en bidragande faktor till ett ökat utnyttjande av metoden. Genom att uppnå lägre vibrationsnivåer och minimera grundvattensänkning får metoden ett ökat mervärde. Sekantpålningsmetoden används i större utsträckning utomlands och det är först nu den börjar brukas i Sverige. Genom att Trafikverket har godkänt sekantpålning som en permanent konstruktion, kan metoden bryta ny mark i Sverige. Sekantpålningsmetoden i sig påverkas ej av det svenska mark- och klimatförhållandet. Det är den teknik som man utnyttjar vid sekantpålningen, som påverkas av de geologiska och hydrogeologiska förutsättningarna. Mark som består av rikligt med stenblock eller varierande sten storlekar bör man använda CSP-tekniken med foderrörsborrning. Tekniker som inte klarar av dessa markförhållanden är CFA och CAP, som istället utnyttjar en augerborr. Dessa tekniker utnyttjas när marken består av fastlera eller friktionsjord, vilket gör arbetet för augerborren betydligt lättare än om marken består av stenblock.   Slutsatsen i rapporten visar att sekantpålning är det dyrare alternativet och att metoden inte kan konkurrera med de mer konventionella stödkonstruktionerna ur kostnadssynpunkt. För att sekantpålningen ska vara fördelaktig måste metoden ses ur ett större perspektiv och hänsyn tas till omgivningspåverkan och markförhållanden. På så sätt kan ett mervärde skapas. Metoden lämpar sig väl i innerstadsmiljö med närliggande byggnader, då buller och vibrationer är en påverkande faktor. Projekt som har utnyttjat sekantpålningsmetoden har varierande kostnader, då de har använt olika sekantpålningstekniker. Vid Norra länken 12 och 22 tillämpades CSP-tekniken som hade en kapacitet till att göra 2,5 pålar per dag till en kostnad av 11.500 kr/m². Vid Bargers plats i Malmö tillämpades CFA-tekniken till en kostnad av 2.500 kr/m². Vid Folkungagatan i Stockholm användes CAP-tekniken till en kostnad av 4.500 kr/m². Metoden har både för och nackdelar. Fördelarna är att metoden är flexibel vilket innebär att den kan anpassas efter önskad geometri. Metoden bidrar till mindre vibrationer som i sin tur minimerar risken för sättningar. Nackdelarna är att sekantpålning är dyrare än konventionella stödkonstruktioner p.g.a. att metoden är tidskrävande. Vid sekantpålning som permanent stödkonstruktion görs efterspänning av ankarstag som är tidskrävande. I rapporten presenteras byggprojekt där sekantpålning använts. Projekt som redovisas i rapporten är Odenplan station, Spjutmo kraftstation, Norra länken 12 och 22, Bagers plats och Folkungagatan. / The goal of the report is to present machines, staff and requisite experience data within secant piling. The information may be utilized in comparison with other piling methods by corporations. Secant piling is used as a support structure whose task is to keep the soil from sliding in to the pit during excavation. Its positive aspects of the environment are a contributing factor to increased use of the method. By achieving lower vibration levels and minimize the reduction in the groundwater level, the method adds value. The secant pile method is extensively used abroad and nowadays it begins to be operated in Sweden. Now when Trafikverket has approved secant piling as a permanent structure, the method can lead to more usage in Sweden. The secant pile method in itself is not affected by the Swedish soil and climatic condition. It is the technique you are utilizing when using secant piling that’s affected by the geological and hydrogeological conditions. Soil that is consisting of boulders or variable stone sizes should use CSP technology with casing drilling. Techniques that don’t work in these soil conditions is CFA and CAP, which instead uses an auger drill. These techniques are utilized when the soil consists of solid clay or friction soil, which makes the work of the auger drill much easier than if the land consists of stone blocks. The conclusion of the report indicate that secant piles are the more expensive option, and that the method cannot compete with the more conventional support structures in that regard. To understand that secant piles will be beneficial the method must be seen from a broader perspective and you have to look at the impact of the surroundings and the soil conditions. In this way, added value is created. The method is suitable in urban setting with nearby buildings, where noise and vibration is an influencing factor. Projects that have embraced the secant pile method have varying costs, since they have used different secant pile techniques. At Norra länken 12 and 22 they used the CSP technology that had a capacity to make 2.5 piles per day at a cost of 11,500 SEK/m². In Bagers Plats in Malmö they used the CFA technology at a cost of 2,500 SEK/m². At Folkungagatan in Stockholm they used the CAP technology at a cost of 4,500 SEK/m². The method has both advantages and disadvantages. The advantages are that the method is flexible which means that it can be adapted to the desired geometry. This method helps to reduce vibration, which in turn minimizes the risk of subsidence. The disadvantages are that secant piling is more expensive than conventional supporting structures because of the method is time consuming. When secant piles that are used as a permanent support structure the anchor rods have to be tightened often and that is time consuming. The report presents the construction projects where secant piling is used. Projects presented in the report are Odenplan station, Spjutmo kraftstation, Norra länken 12 and 22, Bagers plats and Folkungagatan.