GROUND MODEL · SITE INVESTIGATION
Soil Investigation & Ground Characterization
Plan reliable ground investigations through desk studies, boreholes, sampling, in-situ tests and groundwater observations—connecting ground facts to engineering decisions.
ENGINEERING OVERVIEW
Better monitoring starts with a credible ground model
Ground conditions control the design of foundations, excavation support, tunnels and monitoring plans. In Hong Kong, variable fill, residual soils, completely decomposed rock, boulders and groundwater can make unsupported assumptions costly. A good site investigation integrates historic information, reconnaissance, properly located in-situ work, laboratory testing and geological interpretation. GEOOE contributes an engineering-technology perspective to site-investigation planning and the translation of findings into monitoring needs.
The aim is not the largest number of boreholes; it is the right level of subsurface evidence for the decisions being made.
ENGINEERING CHALLENGES
What changes the monitoring decision?
Real-world constraints influence how a technically sound monitoring strategy is designed.
Lateral variability
Geology can change rapidly between investigation locations, particularly near rockhead and weathered rock profiles.
Disturbed samples
Handling, transport and sampling method may alter water content, fabric and test interpretation.
Groundwater misunderstood
Standpipes and piezometers record conditions in particular horizons and require correct installation and equilibration.
Missing investigation context
Borehole logs without spatial coordinates, datum, test standards or interpretation can be difficult to use in design.
METHODS & COMPARISONS
Choose investigation methods by the uncertainty to resolve
A useful method must measure a relevant variable, maintain a reliable baseline and support a decision.
| Method | Primary evidence | Typical engineering purpose | Limitations to plan for |
|---|---|---|---|
| Desk study and walkover | Records, maps, geology and site conditions | Design the investigation and identify hazards | Historic data may be incomplete or outdated |
| Boreholes and sampling | Strata, recovered samples and in-situ observations | Confirm stratigraphy and obtain test materials | Spacing and sample quality control resolution |
| SPT and related in-situ tests | Penetration resistance under a defined procedure | Supplement soil profiling and empirical assessment | Energy, soil type and procedure influence results |
| CPT/CPTu where suitable | Continuous cone resistance and pore-pressure response | Characterise stratigraphic transitions and soil behaviour | Obstructions and ground applicability |
| Groundwater instruments | Water levels or pore-pressure time series | Understand hydraulic boundaries and construction sensitivity | Filter zone and reading stabilization are critical |
| Geophysical survey | Indirect seismic or electrical response | Interpolate conditions and target anomalous zones | Requires geological or borehole control |
ENGINEERING APPLICATIONS
Explore the relevant topics
Choose a subject area for a more detailed discussion of technical limitations and engineering context.
Deep Excavation
Use the ground model to choose wall and groundwater monitoring.
Explore Deep Excavation ↗Tunnel Interfaces
Identify variable ground ahead of underground works.
Explore Tunnel Interfaces ↗Slope Engineering
Investigate weathering profiles, water and potential movement.
Explore Slope Engineering ↗Geophysical Survey
Pair geophysics with conventional investigation evidence.
Explore Geophysical Survey ↗Ground Monitoring
Translate investigation uncertainty into meaningful monitoring locations.
Explore Ground Monitoring ↗ENGINEERING APPROACH
A disciplined route from field evidence to action
Successful monitoring connects requirements, measurement, validation and accountable review.
01 · Desk study
Review previous boreholes, maps, development history and nearby works.
02 · Conceptual model
Identify likely units, groundwater regimes and key unknowns.
03 · Targeted investigation
Plan accessible exploratory positions and appropriate tests.
04 · Quality and interpretation
Check logs, coordinates, test quality and unexpected strata.
05 · Monitoring integration
Align parameters and instrument locations with the ground model.
ENGINEERING CHECKLIST
Questions to answer before deciding
These questions help shape a realistic scope and avoid selecting technology before defining the engineering problem.
- Are the investigation locations adequate for the proposed structure and geological uncertainty?
- Has the chosen method been matched to expected soil, rock and obstructions?
- Are borehole elevations, coordinates and depths referenced consistently?
- Are groundwater readings taken in appropriate horizons and over sufficient time?
- How will discrepancies between boreholes and geophysical responses be resolved?
- Which design or monitoring decision requires each proposed test?
TECHNICAL BOUNDARIES
Limitations and professional judgement
GEOOE’s site-investigation content explains engineering methods and coordination approaches; it does not imply ownership of an extensive drilling fleet or that drilling can proceed without appropriate permits and specialist arrangements.
Investigation findings remain subject to uncertainty. Site-specific design and construction decisions require qualified professional assessment and applicable specifications.
FAQs
Frequently asked questions
How many boreholes does a project need?
Can geophysical methods eliminate drilling?
Why should groundwater be observed beyond one visit?
How does investigation improve monitoring design?
RESEARCH & RELATED CONTENT
Official references and further reading
These official resources provide primary-source context; additional GEOOE pages explore the methods in more depth.
GET IN TOUCH
Discuss Your Project
Share your asset type, location, engineering concern and any access constraints. We can discuss a practical technical approach before defining scope, responsibilities or delivery terms.