AECOM. Sven Thorin (MSc, DIC), AECOM

Transcription

1 Sven Thorin (MSc, DIC),

2 Value of historical ground data for large infrastructure projects Sven Thorin (MSc, DIC), Senior Geotechnical Engineer, David Och (PhD), Principal Engineering Geologist, WSP Tim Rannard, Associate Director,

3 Source: Daily Telegraph Value of historical ground data AS requires literature review & initial assessment of site conditions Why collect existing data prior to any fieldworks? Reduce SI scope & associated risk : avoid areas with sufficient data Identify hazards & gaps in info, update design & target SI scope Develop initial Ground Model (mass & material characterisation) Yet, many large projects rush to intrusive fieldworks Source: AFP

4 Identifying hazards and gaps in information Identify structural features (dykes, fault zones, joint swarms, ) Identify weathering features such as infilled palaeo-valleys Define geological boundaries Provide an indication of groundwater levels Identify fill, potential contamination and buried assets

5 Example: backfilled brick pits in Sydney

6 Example from Sydney Metro CSW (1/2) Data-sharing approach > 50 historical projects Single ArcGIS database (6000 bhs) Single gint (AGS4.0) database (450 historical bhs) Size of statistical significance

7 Source: Sydney Metro City & Southwest Source: Och et al Example from Sydney Metro CSW (2/2) Source: Herbert 1986

8 Data collected today is tomorrow s historical data Digital data has become the most useful deliverable Save to open formats, unencrypted, uncompressed -> increase life expectancy Proprietary (e.g. xlsx, tiff) + potentially zip, PDF, etc could become unreadable Open (plain text, CSV, XML, png, html) Data Interchange formats Keep track of versions, combine information in single project database Be aware of Ownership & Reliance Be aware of inherent limitations due to data source (e.g. mining, enviro) Key aspects: Quality and consistency, Sample Photography, Location

9 Consistency is as important as quality Technical Workshop with Client / TA Technical Induction to field engineers, reviewers Use Technical Instruction in contracts & keep in the field Source:

10 Sample photos are a key factual record Clean core Include scale and factory-printed colour control patch Review on a large screen before testing Take additional close-up shots of core Photograph soil samples

11 Most of the data is unusable without spatial information Coordinate datum, projection and zone Elevation datum and depths references Inclined vs vertical: Length? Depth? Expected accuracy of survey All bearings with a suffix (MN/TN) prefer TN Register changes during project

12 Visualise, Manage, Share and Store? Data Interchange Formats - Geotechnical Databases SHARE - - MANAGE Geotechnical Data 3D Geological Model INTERPRET Spatial Database - VISUALISE Other Software DESIGN

13 Spatial databases: what data is available? Massive rise of open-source GIS National map-based indexes e.g. NZDG, BGS - GeoIndex, BRGM-BSS Various licencing schemes Only require basic attributes: X,Y,Z, year, depth, link, custodian In Australia: Geological Survey NSW: mostly mining No central custodian agencies & consultants have own databases No requirement to provide data

14

15 Geotechnical databases E.g. Bentley gint, Keynetix HOLEbase SI, EsDAT, EQuIS Manage, interrogate, process, present and export data Customised and proprietary Moving to SQL Servers and cloud platforms Use correspondence files to import/export to AGS

16 AGS Data Format Exists since 1992 to transfer SI, laboratory and monitoring data in an open format (ASCII CSV) Customized AGS3.1 (AU, HK, SIN) or AGS4 (NZ) versions Although key deliverable and relevant to BIM, lack of familiarity amongst clients, consultants and laboratories AGS files not requested, late or incomplete DIGGS potential future alternative (GML XML) Table Name Field Names Records

17 Conclusion Historical ground data can yield considerable value, esp. in urban settings for large projects The industry is poor in extracting this value Data collected today is tomorrow s historical data: quality & consistency, photo records, spatial information, change management Spatial databases, data exchange files, geotechnical databases & 3D models are complementary Open centralised national databases are key to know what data may be available Drive required across clients, consultants and labs to customise a national AGS format New data and data collected as part of desktop studies should be requested in AGS format