1. GEOLOGICAL INVESTIGATIONS FOR
ENGINEERING WORKS AND
DISASTER PREVENTION
KYI KHIN
JICA SEMINAR
SAKURA Tower, Yangon, Myanmar
(10th May, 2005)
Some examples and case studies
in JAPAN

2. Geologist: Design the Earth
Engineer: Design the Materials

3. Related Works
National/Local
Underground Structures, Tunnels Boxes, Bridges Cut and Fill
Public Works
Buildings Rails/Roads Irrigation/Dam
Urban Planning
Landscaping Gardening Environmental Assessment
Inspections, Mitigation, Disaster Prevention
Earthquakes Volcanism Typhoon
Landslides, Collapses, Rock Falls, Debris Flows, Subsidence, Coastal erosions, River Floods etc.,

4. Ｔｅｃｔｏｎｉｃｓ ｏｆ Ｊａｐａｎ
Eurasia Plate
Philippine Sea Plate
Pacific Plate
North America Plate

5. Natural Hazards in Japan
Active Fault after Earthquake
(Kobe Earthquake, 1995)
Volcanic Eruptions
(Sakurajima, 1914)

6. Collapse/Rock Fall Landslide
Nagano Pref. 1986Yamanashi Pref. High-way

7. Investigations
 Surface Investigations
- Site Investigation, Land Surveying, Remote sensing,
Geotechnical Mapping, Outcrop mapping, Design Planning
 Subsurface Investigations
-Drilling, Sounding, Elastic wave, Seismic, Echo-sounding, etc.
-Ground water (permeability, pore water pressure etc.)
-SPT, LLT, CBR, Cone (CPT), Vane Shear Test
-Samplings (water, soil, Rocks, Concrete etc.)
-Borehole camera, inclinometer, AE sensors etc.,
 Laboratory Tests
-Soil, water, Rocks, concrete, metals

8. Site Investigation
 Topography, Slope, Overhang, Scarp, valley, stream
 weak planes (Bedding Plane, Joint, Lamination,
Cleavage, Foliation)
 Geological outcrops, Folds, dip/strike, faults (minor,
major, active, inactive), metamorphic grade,
weathering
 Surface water (volume, speed, erosion), pond,
springs, lake, seepage
 Plantation, Forest, tree alignment, fallen trees
 Rock Floats, old collapsed place, cracks, subsidence,
Traffic, old construction, civilization

9. Preliminary Survey
Regional Geological Maps
(S=1:25000-1:50000)
Air-photo Interpretations
(S=1:5000-1:40000)

10. Surface Investigation
Land Surveying, Route Planning, Design Planning
Cut Slope Plan
Fill Slope Plan

11. Geotechnical Mapping
-Outcrop Mapping
-Dip/strike, Joints, Faults
-Collapsed zones
-Seepage zone
-Vegetations
-Cover-soil (types, thickness etc.)
-Floats
-Previous Man-made structures
-Previous investigation points
-Planned investigation points
-Photo points

12. Consider the Problems
Embankment or Fill
Cut and Fill
Buildings
1. Liquefaction
3. Consolidation １
２
３
2. Bearing capacity
4. Bearing stratum
4
Embankment or Fill
Cut and Fill
1. Slope stability
2. Ground water
3. Fill materials/Volume
4. Consolidation/Settlement
Buildings
1. Bearing stratum
2. Liquefaction
3. Consolidation/Settlement

13. Investigation at Dam site
1.Regional Geological Mapping
2.Dam Axis Survey (Left/Right)
3.Landslide Possibility Survey
4.Environmental Impact
Shear Zone
WL
Down-stream (Left Bank)
Up-stream (Left Bank)
Geological Map for Dam-Axis Planning

14. Other Preliminary Investigations
Sketches in Trench Geophysical Explorations
Rock-quality
Slip Zones, Fault planes
Geological structures
Stratum
Fault plane (weak Zone)
Geological structures

15. Alluvial Plain
1.Volcanic Layers
2.Clayey sandy gravels beds
3.Sandy gravels
4.River Sands/Terraces and Flood
Plain deposits
5.Peat/Organic soil
6.Sand bars
7.Beach sand
8.Man-made embankments
9.Swamps
10.Bed rocks
F
l
u
v
i
a
l
Fluvial Plain FanDelta
Outflow dangerous Zones Seepage flow patterns

16. Creep
Flow
Slump/Slide
Rock glide
Cover soils, talus over clayey
layers (Thickness=5-10m)
Heavy rain, flows of rock and
soil debris (L=100sm, T=5-
10m)
Circular slip (soft
rocks)
Slump=T:10-15m
Slide= T:15-30m
Compound slip
Fault, shear zone,
dykes, folds etc.
T:10-30m,L:30-50m
Unnatural Topographic features
Contour lines, sag ponds, collapsed
Zones, tree alignments, seepage,

17. Investigation of Topography Ⅰ
Valley in Mountain site
・Cover soil (thickness, soil type)
・Collapsed soil, Bed rocks
・Failure, slip plane, collapsed area
・Possible slide area
・Cover soil (thickness, soil type)
・Slope angle (Run-off)
・Seepage zone, groundwater
・Over-hang, Bank-erosion
・Failure, slip plane, collapsed area
・Possible slide area
・Bed rocks
Up-stream Areas

18. Investigation of Topography Ⅱ
Landslide Topography
-Swamp, pond, slip scarp, collapsed
zones
-Contour shape, alignment
-Seepage, springs
-Displaced materials, cracks (open or
closed), slip plane (active, in-active)
-Zone of bulging, depression,
subsidence
-Cover soils, collapsed materials,
Bedrocks, shear zones, faults,

19. ROCK SLOPE FAILURES
Dip Slope of
Sedimentary &
Metamorphic rocks
Planar failure Wedge failure Toppling failure Circular failure
Two intersecting
discontinuities with a
line of intersection in
Metamorphic & folded
Sedimentary Rocks
Along the
columnar joints or
slab of jointed
block that dip
steeply into slope
Overburden soil,
Volcanic ash beds,
weathered rocks
or heavily
fractured rocks

20. Examples of slope failures in cut-slope (1)
Erosion, Collapse Slope
Dry, Frozen, Heavy rain,
gully erosions in Volcanic ash
beds, Tuff, Weathered Rocks,
granite soil, soft rocks
Overhang slope
Volcanic flow beds, Terrace
deposits, Boulders in
sedimentary sequences
Fall or Slide
Along the Cracks, joints,
bedding planes
Collapse
Boundary between cover soil and
highly weathered bed rocks by
ground water seepage

21. Examples of slope failures in cut-slope (2)
Weathered Zone of Bed rock
Bedding, Joint &Fault plane slide
Sedimentary, Tuff, Metamorphic
Rocks
Large scale landslides
Geological structures, Ground water
and bed rock natures
Dip slope, weak planes (clay layers),
Fault Zone (Crushed zone)
Deep slope in columnar jointed rocks

22. Examples of slope failures in Fill-slope (1)
Shallow fill-slope failure
Materials=Soil, Tuff, Volcanic
ash layers
Causes=Un-compaction, Heavy
rain, earthquakes, slope angles,
underground water
Mitigation=Compaction, drain
systems, re-slope, select fill
materials

23. Examples of slope failures in Fill-slope (2)
Embankments across stream
Construct drainage system
Impermeable soil (Clay, Mud)
Underground water effect
Soft ground such thick clay or
mud
Top of landslide Zone

24. Examples of Rock Fall (1)
Pull-out/Drop out
Terrace deposits
Diluvial/Alluvial deposits
Boulder conglomerate
Collapsed soils
Glide/Slide
Jointed Rocks
Alternated sequences
Concretions
Aeolian deposits

25. Examples of Landslide (1)
-Fault Zone (Brecciaed Zone)
-Weathered Zone
-Man-made construction
Bed rock Slides
Weathered rock Slides
-Valley or Ridge, spur
-Heavy rain, Earthquakes
-Man-made construction

26. Examples of Landslide (2)
Talus/Colluvial soil Slides
-foothill, valley
-pebbly, gravelly soils
-block slide
-Snow, typhoons, heavy rains
-Man-made effects
Soft soil Slides
-foothill, valley
-Clayey soils
-Hot spring, brecciaed zone
-block slide
-Snow, heavy rains, river erosions
-Man-made effects

27. Examples of Debris flows and Mud flows (1)
-Topography
-Slope angle (10°-45°)
-Snow, typhoons
-Heavy rains
-Up-stream geology
-Dam-breaking
-Landslides at up-stream
Controlling Factors

28. SUBSURFACE INVESTIGATIONS
Assign Boring Points for Cut-Slope

29. Plan for Subsurface Investigations
Elastic Wave Test Points Inclinometer and Tilt Meter Test Points

30. Drilling Investigations
Hydraulic-feed Boring Machine Cone-Penetration Test Machine

31. Others Drilling Tests
Sweden Sounding Test Machine Sensor-attached Cone

32. SPT Count and Sandy soil Compaction
Very Loose
Loose
Medium
Dense
Very Dense
φ
SPT Count and Hardness of Clayey Soil
Very Soft
Soft
Medium
Hard
Very Hard
Compact

33. Core interpretation for Rock
RQD=Rock Quality Distribution
A B CH CM CL D

34. Rock Classification
for Engineering Purposes
SPT Count and its
Safety Factors

35. Boring and Cone Investigations

36. Inclinometer test in Landslide Area

37. Inclinometer Test Machine

38. Subsurface Investigation and Interpretation
?

39. ＣＯＮＣＬＵＳＩＯＮ
 General interpretation both Surface and
Subsurface Investigations
 Importance of Geological Mapping
 Importance of Alluvial Plain Sequence
stratigraphy and it’s geotechnical
relationships
 Importance of Regional hazard Maps