The glacial and periglacial history of a Middle Pleistocene ice-margin of the British Ice Sheet (BIS) in north Buckinghamshire, England and its influence on geotechnical variability

• Main Author: Price, Simon
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Clare Hall 2019
• Subjects: quaternary; geotechnical engineering; glacial; periglacial; BRitish Ice SHeet; Buckingham; Ice; Ice Sheet; permafrost
• Online Access: https://doi.org/10.17863/CAM.42280; https://www.repository.cam.ac.uk/handle/1810/295218

Resilience is an important factor in the design and operation of new and existing linear infrastructure. Temporal and spatial variability in Quaternary, cold-climate processes, including deposition and weathering of glacigenic sediments and bedrock, subglacial drainage and permafrost development, has resulted in abrupt lateral and vertical anisotropy in the natural geotechnical state of the ground. The ability to anticipate vertical and lateral changes in the physical properties and structure of the shallow subsurface remains a major challenge for geotechnical design. This research uses a combination of field and laboratory techniques to investigate the Middle Pleistocene history of part of north Buckinghamshire and its potential influence on geotechnical variability of till and Oxford Clay mudrocks. The project area was chosen because of its position relative to the proposed route of Great Britain’s second highspeed railway (HS2) and its coincidence with a major Quaternary domain divide between lowland glaciated and non-glaciated, landscape assemblages. A regional database of geotechnical properties and behaviour was constructed. The database was used to describe variability in geotechnical property and behaviour parameters, against which the results of the laboratory investigations were compared. Geotechnical laboratory analyses included single- and multi-stage triaxial tests to determine undrained shear strength parameters, stress paths and strength envelopes. Small-strain stiffness was analysed using Hall effect sensors in triaxial compression. Compressibility behaviour was examined using 1D consolidation tests. This was supplemented by index testing, clay mineralogy analysis, geological field logging and numerical dating of glacigenic sediments using optically stimulated luminescence (OSL) techniques. The results of the laboratory investigation, and database parameters, were interpreted against a national framework of spatial Quaternary Domains which relate similar geological and geomorphological landscape ...