Team Members: Alireza Babaee Budiwan Adi Tirta Maryam Izadifar July 2015

1. Team Members:
Maryam Izadifar, Alireza Babaee, Budiwan Adi Tirta
GETUS
Geo-Engineering Techniques for Unstable Slopes
July 2015
Characterization of a rock mass by integrated study of geology,
geophysics, and photogrammetry
Professors:
Laura Longoni, Diego Arosio, Marco Scaioni,
Stephene Garambois, Davide Brambilla

2. Table of Contents
1- Introduction
2- Geological Study
3- Photogrammetry and Laser Scanning
4- Geophysical Study
5- Block Volume Evaluation

3. 1- Introduction
Area of interest
• North of Lecco
• Slope is adjacent to sub-urban road
near Varrena
• The rock is typically hard sedimentary
rock, which is classified as limestone
• The slope itself is quite regular with
average height of 9-10 m, dip and dip
direction 65° and 220

4. Geological Study
Joint Orientation

5. Geological Study
Sets of joint family
Discontinuity
Code
Dip
Directio
n (°)
Dip
(°)
Aperture
(mm)
Joint
spacing
(cm)
Frequency
(1/m)
A1 220 65 10 - -
A2 230 65 15 30 3.33
A3 210 65 1-2 21 4.76
A4 210 65 1-2 19 5.26
A5 210 65 25 17 5.88
A6 210 65 1-2 15 6.67
A7 235 60 1-2 15 6.67
A8 230 55 1-2 6 16.67
A9 240 60 10 12 8.33
B1 110 75 1-2 - -
B2 110 75 1-2 160 0.63
B3 110 75 2-5 150 0.67
B4 120 75 1-2 100 1.00
B5 130 70 2-5 230 0.43
B6 140 80 30 290 0.34
B7 130 75 50 130 0.77
B8 130 75 10 80 1.25
B9 110 75 2-5 50 2.00
B10 110 80 2-5 80 1.25
B11 150 70 50 440 0.23
B12 140 65 50 650 0.15
C1 340 10 1-2 - -
C2 320 10 1-2 240 0.42
C3 340 30 1-2 300 0.33
Classification and condition of discontinuities
In order to have final classification, we made stereo plots
of poles using an equal area projection streoronet of each
discontinuity. Therefore, we were able to see classification
of families of discontinuity as shown

6. Geological Study
Joint Surface roughness
• JRC number is obtained by directly comparing the
actual joint surface profile with the typical profile in
the given chart.
• The measurement of the surface roughness was not
measured for all the joints, but it almost covers all
the measured joints. In this case the average value
of JRC is 12.3
Joint Roughness Coefficient chart
Joint surface roughness of the measurements and JRC numbers

7. Geological Study
Uniaxial compressive strength of intact rock
• For determining the uniaxial compressive strength of rock we can
use the Schmidt hammer (L-hammer).
• Obtain a direct estimate of the compressive strength by knowing
the density of rock.
• at least ten readings that are taken at various locations on each
surface
• the five lowest reading are discounted, and the five highest
readings are used to obtain uniaxial compressive strength
• Based on the highest five reading and the ranging of the
limestone unit weight (23-28 kN/m3) , the average of the
uniaxial compression strength might be between 78 to 115 Mpa
• Considering the unit weight of 25 kN/m3 and the five highest
reading it gives us the uniaxial compressive strength of 91 MPa

8. Geological Study
Shear strength of discontinuity

9. Geological Study
Slope stability analysis ( Markland Tests)
Planar failure
When a single plane of rock slides, a planer failure will occur. In
order to have that sliding, the following geometrical conditions
must be satisfied:
• The plane on which sliding occurs, strike must be parallel or
nearly parallel (within approximately ± 20°) to the slope face
• The dip of the plane must be smaller than the dip of the slope
face
• The dip of the failure plane must be greater than the angle of
friction of this plane
Joint Family
Average value of
dip direction
Average value of
dip
[°] [°]
A 222 63
B 124 74
C 333 17
Slope 220 65
Stereograph representation of joint families
and the slope with great circle for planar failure
evaluation
Planar failure
Criterion Description Family A Family B Family C
1 Slope dip > joint dip
YES
(65°>63°)
NO
(65°<74°)
YES
(65°>17°)
2
Difference between dip directions of
slope and joint < 20°
YES
(2°<20°)
NO
(96°>20°)
NO
(113°>20°)
3 Joint dip > friction angle
YES
(63°>30)
YES
(74°>30)
NO
(17°<30)
Based on the test, joint family A has all the criteria to
have planar failure.

10. Geological Study
Slope stability analysis ( Markland Tests)
Wedge failure
Wedge failure occurs where sliding takes place along the line of
intersection of two planes. The following geometrical conditions
must be satisfied:
• The dip of the slope, must exceed the dip of intersection line
• The dip of the intersection line must higher than friction angle
• Dip direction of intersection line should be almost similar to the
dip direction of slope
To check wedge failure, a circle that shows friction angle on the
stereograph has been considered with dip and dip direction of joint
families. Intersection of friction angle circle and slope great circle
creating an intersection area that is mentioned as a critical area (red
zone in Figure ).
Stereograph representation of great circles of
joint families and slopes, intersections, and also
cohesion=30° for wedge failure evaluation
the intersection of joints A and B sets
satisfied the criteria. Moreover, as shown in
the stereoplot of wedge failure’s test, it can
be observed that the A-B intersection
located inside the critical area
Wedge failure
Criterion Description Intersection AB Intersection AC Intersection BC
1 Slope dip > intersection dip
YES
(65°>58°)
YES
(65°>14°)
YES
(65°>10°)
2 Intersection dip > friction angle
YES
(58°>30°)
NO
(14°<30°)
NO
(10°<30°)
3
Similarity between dip direction of
intersection line and slope (220°)
YES
(190°)
NO
(308°)
NO
(48°)

11. Geological Study
Slope stability analysis ( Markland Tests)
Toppling failure
Toppling failure involves rotation of columns or blocks of rock about fixed base. In the following there
are geometrical conditions that must be satisfied.
• The plane on which toppling occurs must have the same strike of the slope but in opposite direction
• The dip of the plane must be greater than 70°
Therefore, there would be no possibility to have toppling failure in this slope, since all the joint
families did not satisfy the failure conditions of toppling
Toppling failure
Criterion Description Family A Family B Family C
1
similar strike , opposite dip direction
with slope
NO
(YES and NO)
NO
(NO and NO)
NO
(NO and NO)
2 Joint dip > 70°
NO
(63°< 70°)
YES
(74°> 70°)
NO
(17°< 70°)

12. Geological Study
Unitary Rock Volume (URV)
Joint family Spacing, (cm)
Code Minimum Medium Maximum
A 0.02 0.06 0.14
B 0.11 0.50 1.26
C 1.33 2.40 2.67

13. Geological Study
Unitary Rock Volume (URV)
The unitary rock volume (URV) could be calculated by considering the persistence as well:
Empirical method

14. Photogrammetry
Data Acquisition
Objectives:
1) To generate point clouds and orthophotos; [PhotoScan]
2) To get some representative trace for the profiles of geophysical survey; [CloudCompare]
3) To define dip and dip direction of the face derived from point clouds. [CloudCompare]
Images:
- Two groups of images;
- 80% overlapping + random images
Camera:
 Model: Canon EOS-1D Mark IV;
 Lens: focal length 20 mm;
 Resolution of image: 4896x3264
pixels.

15. Photogrammetry
Geodetic Network and GCPs
Ground Control Point (GCP)
geodetic network for photogrammetry and location of 4 stations
- to geo-referencing the images
Geophysical Points
- to extract topography of
geophysical profiles
Local RS
+
2 GPS stations
=
Global RS

16. Photogrammetry
Processing Images (PhotoScan)
Steps for each chunk:
1- Aligning the photos (tie points);
2- Marking some GCPs for geo-referencing (already in Global System);
Camera Calibration (automatically in the software);
Residual error in tie points = 0.5 pixel (3 mm)
Before calibration After calibration
C, XP, YP: Inner orientation parameters
K1, K2, K3, K4: Radial distortion parameters (very small)
p1, p2: decentering distortion coefficients (very small)
B1, B2: affine distortion coefficients (very small)

17. Photogrammetry
Processing Images (PhotoScan)
3- Merging two chunks;
4- Building Dense Cloud;
5- Building Mesh;
6- Texture construction;
7- Exporting the point cloud;
[CloudCompare]

18. Photogrammetry
Orthophoto (PhotoScan)
After building the texture:
- Export the Orthophoto
XZ-Front
Orthophoto from Canon images
Orthophoto from iPhone 4 images (lower resolution and quality)
pixel size = 0.5 cm

19. Photogrammetry
GPR profiles (CloudCompare)
After Importing Point Cloud:
- Segmentation / Extract Sections
- Save Vertices of profiles in text file
- Represent profile in Excel
Distance calculation (comparing with geophysical
and geological results)
H2 profile (exported to Excel)
Topography effect in geophysical results

20. Photogrammetry
Dip and Dip Direction Extraction (CloudCompare)
Option 1:
RANSAC (RANdom SAmple Consensus) Shape Detection plug-in -- Poor results
Option 2:
- Defining block segments with same orientation [by Professor Scaioni]
- Segmentation / Cross section for each block segment
- Manually extracting d and dd (by fitting a plane for each cross section)
Remove vegetation:
Edit / Segment/ Segment Out

21. Photogrammetry
Dip and Dip Direction Extraction (CloudCompare)
Results:
(Comparing photogrammetry and classic geological survey)
Slope and A joint family from
Geological survey
15 planes from photogrammetry
Methods
Average dip
direction [deg]
Average dip angle
[deg]
Geological Survey 222 63
Photogrammetry 209 53
Slope = 220 / 65

22. Terrestrial Laser Scanning
Alignment (CloudCompare)
Two TLS recorded in Local RS
1- Segmentation of two data sets (removing road and trees, etc.)
2- Aligning by ICP (Iterative Closest Points)
- residual error < 1 cm

23. Photogrammetry vs Laser Scanning
Alignment (CloudCompare)
3- Aligning by ICP (Iterative Closest Points)
Point cloud of photogrammetry as reference (will not move during ICP)
Merged point cloud of LS as model (will move during ICP)
- residual error << 1 cm
- higher residual error
Canon
iPhone4

24. Geophysical Study
Introduction
Methods:
 Ground Penetration Radar (GPR).
Objectives:
 a seduo 3D sketch of the main discontinuities
considering areal persistance;
 1D velocity-depth (validation with the thickness layers
based on other surveys);
 Water content (an empirical formula).

25. Geophysical Study
Data acquisition
 GPR with frequency of 1 GHz;
 The resolution (/4) of the GPR measurement is around 2.5 cm considering
typical velocity of limestone (10 cm ns-1);
 Two horizontal profiles (H1, H2) and four vertical profiles (V1-V4);
 One common-mid-point (CMP) profiling;
 Total length of the profiles is about 20 m

26. Geophysical Study
Velocity analysis (stacking velocity)
n 1/v0:n
2 v0:n
2 v0:n t0:n
2 t0:n
[-] [(ns/cm)2] [(cm/ns)2] [cm/ns] [ns2] [ns]
1 0.014 71.43 8.45 71 8.43
2 0.012 83.33 9.13 173 13.14
3 0.011 90.91 9.53 643 25.35
4 0.012 83.33 9.13 1289 35.90

27. Geophysical Study
Interval velocity (Dix’s formula)
n v0:n t0:n (v0:n)2
t0:n-
t0:n-1 Vint thickness elevation
[-]
[cm/ns
] [ns]
[(cm/ns)2
] [ns] cm/ns [cm] [cm]
1 8.45 8.43 602 - 8.45* 35.61 35.61
2 9.13 13.14 1095 4.71 10.23 24.09 59.70
3 9.53 25.35 2305 12.21 9.95 60.77 120.47
4 9.13 35.90 2992 10.55 8.07 42.59 163.06
0
20
40
60
80
100
120
140
160
180
8 9 10 11
Elevation,cm
Velocity, cm.ns-1
Interval velocity
average of interval velocity

28. • Based on the 1D
velocity analysis from
CMP;
• Assuming:
where c is the air velocity (30 cm.ns-1).
28
Vint elevation c Ka qv
[cm/ns] [cm]
[cm/
ns] [-] [-]
8.45 35.61 30 12.6 0.24
10.23 59.70 30 8.6 0.16
9.95 120.47 30 9.1 0.17
8.07 163.06 30 13.8 0.26
Geophysical Study
Water content (Topp, 1980)

29. Geophysical Study
Reflective layers
V1
V2
V3
V4

30. • Profile at normal direction
with respect to dip
direction of surface;
• Areal persistence;
– Persistence based on
reflective profiles ;
– Linear interpolation
between two data;
30
4- Geophysical Study
4-7 Sketch of a Pseudo-3D of discontinuity

31. 5- Block Volume Evaluation
3DEC calculation
 Model 1: 100% persistency for all the discontinuities; [comparable with first
calculation of the empirical formula]
 Model 2: 100% persistency for A1,A2,A5,A9 and 50% persistency for A3,A4,A6,A7,A8;
 Model 3: 100% persistency of A1 and A2, 96% of A5, 83% of A9 and 0% persistency
of A3, A4, A6, A7, A8. [comparable with second calculation of the empirical formula]
From geophysical surveying
Assumption: Joint of one family have same d % dd (parallel)

32. 5- Block Volume Evaluation
Granulometric curves & comparison
3DEC Model 1
(100% persistence)
Model 2 Model 3
(persistence according
to geophysical survey)
Empirical
Formula
(100 %
persistence)
(persistence according
to geophysical survey)
V90 0.89 1.1 2.8 V max 0.5 0.67
V50 0.3 0.3 0.55 V med 0.08 0.107
V10 0.04 0.02 0.02 V min 0.003 0.004
Model 1:
V min (empirical) = 0.003 m^3
V10 (3DEC) = 0.04 m^3
Model 3:
V min (empirical) = 0.004 m^3
V90 (3DEC) = 0.02 m^3
Decreasing the persistency has higher
effect in 3DEC (real geometry) than
empirical calculation
20 classes were defined

33. Thank You For Yours Attention