Specialist Geotechnical Advice

New Cruise Terminal. – We were contacted to provide specialist geotechnical advice on the potential effects of noise and vibration caused by the installation of large diameter steel tubular piles for a new cruise terminal. Of particular concern was the potential effect on the marine life and over what area the marine life would be affected. Our findings recommended steps that could be taken to mitigate the levels of noise and vibration to reduce the risk of harm.   C Hobbs Associates were able to draw on experience gained in providing similar geotechnical advice on a review considering noise levels caused by the construction of a new loading berth in Bunbury Western Australia. 

Manchester Ship Canal. – In late December 2015 Storm Eva cause flooding in the canal which resulted in severe damage to about 160m of canal bank. Drilled ground anchors were needed to tie back a new combi pile wall stabilising the damaged bank. However, during the drilling of the anchors, movement was recorded beneath nearby structures and work was stopped. We were commissioned to provide specialist geotechnical advice about the cause of the movement and what changes could overcome these problems. Researching the probable cause of the movement, we highlighted changes ensuring that further movement could be kept to controllable levels. 

Chernobyl. – Construction of the new safe confinement shelter over the reactor building number four at the Chernobyl nuclear power plant, problems were encountered in forming the CFA piles in the active zone. Bechtel contacted us to ask for our help to resolve the problems they were having on site. After reviewing the computer records for the pile installation and the test pile results we identified where changes in construction method would significantly impact the quality and speed of construction. Seeing construction at the site quickly confirmed our findings. Our recommendations to the construction team resolved the problems that the site team were having.  Take some time to watch the arch being slid into place here.

Bishop’s Stortford. – A house builder called to say that their piling contractor was unable to form CFA piles on their site in Bishop’s Stortford. Our role was to research the reasons why the piles could not be formed and what solutions could be implemented so the project could be completed.  After reviewing the site investigation documents, pile records and previous projects close to the site we discovered there were dissolution features under the site preventing the formation of the piles. We proposed the scope of further ground investigation that found the full extent of the features. The solution we proposed was to perform compaction grouting to stabilise the dissolution features and reduce the effects of ground movement on adjacent buildings during the successful completion of the piling.

Geotechnical Design and Innovation

Retaining Wall Design – C Hobbs Associates regularly prepare geotechnical design reports for the construction of embedded retaining walls to retain unstable slopes and for the construction of basement structures. Our more recent contracts include the design of a bored pile retaining wall at Cayton Stud near Reading; a piled basement retaining wall Bristol and a piled king post retaining wall in Barnsley.

Bearing Pile Design – C Hobbs Associates prepare geotechnical design reports for bearing pile design from as little as 4 piles for a house extension to more than 1,000 piles for for much larger projects. Projects of note include the design of bearing piles to a new statue to Nehandu in Harare, Zimbabwe; designing bearing piles for a new hotel near Oxford and the design of steel cased driven piles for a new housing development near Welney, Cambridgeshire.

Ground Movement Analysis – Planning conditions for a new 24 storey tower block in South London required a ground movement assessment arising from the installation of the piled foundations. Using computer modelling techniques, we were able to show that the predicted induced strains surrounding the nearby tunnel would not be sufficient to cause any damage.

Differential Settlement – Heavily loaded centre core foundations near to more lightly loaded column foundations can give rise to high differential settlement and hence structural instability. Our analysis of a tall building’s foundations showed that there was a significant risk of large differential settlement occurring. By modelling the building foundations and structural loads, we modified the foundation design moderating the differential settlement to a level that the structure could sustain. 

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