Event organised by The British Tunnelling Society Young Members
Horizontal directional drilling (HDD) is a trenchless method commonly used for pipeline and cable installation. It is ideally suited to crossings beneath natural and man-made obstacles and offers substantial cost, safety and environmental benefits. Despite the wide use of HDD, there remain concerns regarding project risk in certain situations. Key to HDD success is good management of the drilling fluid and the avoidance of excessive mud loss.
Fundamental risks in HDD arise from pressure build-up in-bore leading to hydrofracturing of the ground, heave of the overburden and mud loss – either to formation, subsurface infrastructure or up to the surface. Poor cuttings transport is a main trigger for bore blockage, leading to potential hydrofracture and the manifestation of the hazards associated with these risks.
In this lecture, a case study involving HDD bores for cable landfall of an offshore windfarm is discussed. The aforementioned risks associated with mud loss are most severe in this type of HDD where drilling starts at a clifftop and descends to punchout in the seabed. In-bore pressures before punchout are elevated by the hydrostatic head of the drilling fluid from the clifftop entry pit.
Other geotechnical challenges encountered onsite will be discussed, along with the analysis of rare annular pressure monitoring data which provided valuable insights into the behaviour of cuttings in the bore.
This lecture concludes with some lessons learnt, recommendations to minimise the risks of hydrofracture and bore blockage, and advice to other young engineers interested in this field.
Following the event, there will be a networking session with drinks at ICE Kendal's bar sponsored by Geotechnical Consulting Group (GCG).
GCG is a leading firm of highly qualified consultants, comprising geotechnical engineers and engineering geologists, who pool their expertise to provide a comprehensive specialist consulting service in geotechnics.
The BTS is a dynamic group of tunnelling professionals sharing knowledge within the industry.
Geotechnical Consulting Group (GCG)
Geotechnical Engineer
Serena joined Geotechnical Consulting Group (GCG) in 2021 as a geotechnical engineer after she completed her MSc in Soil Mechanics at Imperial College. She has also been a science, technology, engineering, and mathematics (STEM) ambassador since 2021.
Serena has worked closely with developer and contractor clients on various energy, infrastructure, and building projects within the UK and internationally. Her work has a focus on early-stage optioneering as well as advising clients on a range of geotechnical risks throughout the project lifecycle.
From 2022 to 2023, Serena took up a technical advisory role as the on-site geotechnical engineer for an offshore wind developer for their cable landfall horizontal directional drilling (HDD) works for an offshore windfarm. During her site work, she contributed to overcoming several interesting geotechnical and drilling-related challenges. She recently published and will present a paper related to her site work at the European Conference on Soil Mechanics and Geotechnical Engineering (ECSMGE 2024).
Aimed at students, this series of seven webinars which runs until May 2025 will enable you to learn about professional life from recent graduates from across the industry.
This is an opportunity for Technicians to gather online to discuss ways in which we can help ourselves, each other and the ICE to provide ongoing learning and experience in the wide world of civil engineering.
The last in our series of online events for new engineers and technicians starting their Initial Professional Development (IPD). It is an opportunity to learn about the level of understanding needed for to demonstrate the Knowledge (K) level on an ICE training agreement or mentor supported scheme.
