This issue of Geotechnical Engineering contains a Briefing article, followed by seven technical articles and a discussion contribution. Geotechnical engineers have often had to operate in a ‘data-poor’ world. This issue contains papers that present and analyse large quantities of geo-data collected from a variety of sources. There is also a strong link to design problems. In their Briefing article, Wilkins et al. (2017) highlight that a key set of improvements has now been incorporated into BS 8006-1 ‘Code of practice for strengthened/reinforced soils and other fills’. This is a useful communication for the geotechnical community.
Three detailed case study papers then follow. Bloodworth and Houlsby (2017) present a detailed case study on the ‘pre-vaulting’ tunnelling beneath some masonry buildings in the Ramsgate area. The authors' report that the monitored buildings exhibited a lower damage category than what would have been predicted using more traditional theories. Kumar et al. (2017) present the results of a large piling project from Vietnam and calibrate a finite-element model to study a combined pile-raft foundation system. They conclude (among other things) that the soil–pile–raft interaction factor governs the number of piles required. Larkela et al. (2017) describe the results of field testing of a vertical drilled ‘sheet pile wall’ from a site in Finland, and the suitability of the wall as a retaining structure is then examined, with the authors reporting good performance.
Geotechnical databases are highly valuable for designers and modellers as they allow for the variability of key parameters to be estimated as well as generate useful correlations (cf. Kulhawy and Mayne, 1990). Ouyang and Mayne (2017) make use of spherical cavity expansion theory to derive new relationships between piezocone and flat plate dilatometer test data that have been assembled from many sources into a large database. The use of the new relationships is demonstrated with two mini-case studies: Osnøy in Norway and Bothkennar in Scotland. Baroni and Almeida (2017) present a large field database of tests on undisturbed samples from the Jacarepaguá Lowlands in Rio de Janerio, Brazil, to establish correlations between soil compression index, natural water content, void ratio and liquid limit and then compare these correlations to others found in the literature. The authors' correlation between compression index and liquid limit is found to exhibit the greatest deviation from similar correlations reported in the literature.
The next two papers are more analytical in nature. Razavi and Bonab (2017) study soil nails in service using a three-dimensional finite-element model to perform a detailed parametric study. Xiao and Guo (2017) derive useful formulae that can be easily implemented in consultancy office spreadsheets to determine anchor forces for deep excavation design work.
The issue concludes with a discussion article with contributions by Cui, Zheng, Zhang and Zhang (Jeffrey et al., 2017). Discussion articles are very useful and here the authors of the original double set of papers, Jeffrey et al. (2016) and Knappett et al. (2016), are able to clarify some aspects of the original work.
On behalf of the Editorial Panel I hope that you enjoy reading the articles in this issue.
