Szalai*, S., Szokoli*, K., Metwaly#, M., Tóth $, Á., Wesztergom*, V.* GGI of the Hungarian Academy of Sciences, Sopron, Hungary, szalai@ggki.hu

# Archaeology department, college of tourism and archaeology, King Saud University, Saudi Arabia$ Department of Physical and Applied Geology, Eötvös Loránd University, Budapest, Hungary

The 8th Congress of Balkan Geophysical Society, 4–8 October 2015, Chania, Greece

Fracture system mapping using Pressure Probe method

Outlines

Introduction- Site description- Measuring method- Field results- VerificationConclusions

Study site

P1

P2(long profile)

N6N4N2N0S2S4S6S8

S10S12S14S16S18S20

N

Danube

N

The landslide area with the measuring profiles

The directly visible main fracture (MF)

study site

Fractures of the Vár Hill

~ 1 mloess

Study site

S10

S8

S6

S4

S10

S8S6S4

N

2 m

~ 0.5 m

measured quantity penetration depth in cm

maximum penetration depth

30 cm

probe weight 2.790 g

recommended drop height is 1m14 cm

12 cm 5.6 cm

diameter of the metal rod: 10 mm

50 cm

scale

Technical specifications of the probe and execution of the measurement

Cone Penetration Test

Exploration of a fracture

step 1

step 3step 2

Principle of the measurement

d

3d

0 0.8 1.6 2.4 3.2 4 4.8 5.6 6.4 7.2 8 8.8 9.6 10.4 11.2 12 12.8 13.6 14.4 15.2 16 16.8 17.6 18.4

-31

-25

-19

-13

-7

Distance (m)

Pene

trati

on d

ept (

cm)

Pressure Probe result

0.00 0.70 1.40 2.10 2.80 3.50 4.20 4.90 5.60 6.30 7.00 7.70 8.40 9.10 9.80 10.5011.2011.9012.60

-31

-28

-25

-22

-19

-16

-13

-10

-7

Distance (m)

crew member 1crew member 2

Pene

trati

on d

epth

(cm

)

DanubeMF

Repeability of the PreP measurements

0.3 2.7 5.1 7.5 9.9 12.3 14.717.119.5 21.924.3 26.729.1 31.5 33.936.338.7 41.143.5 45.948.3 50.7 53.1 55.557.9 60.362.7 65.167.569.9

-31-27-23-19-15-11

-7

Distance (m)

Pene

trati

on d

eph

(cm

)

3+3+4=10

MF

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70

-31-27-23-19-15-11

-7

Distance (m)

Pene

trati

on d

epth

(c

m)

0.2 7 13.8 20.6 27.4 34.2 41 47.8 54.6 61.4 68.2000000000001

-31-27-23-19-15-11

-7

Distance (m)

Pene

trati

on d

epth

(c

m)

5+6+6=17

5+3+6=14

sampling distance: 10cm

sampling distance: 20cm

sampling distance: 30cm

The effect of the sampling distance

Danube

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 8.5 9 9.5 1010.51111.51212.51313.51414.51515.51616.51717.51818.5

-31

-25

-19

-13

-7

Distance (m)

Pene

trati

on d

ept (

cm)

1 2 3

Danube

profile N4

MF

S8

S12

S16

S20

P1

N6

S4

S6

S10

S18

N4N2

N0

S2

S14

P2 N

Interpreation of the PreP results

4

1b

2a

1a

3d

3c

3b

3a

2b

8a

7

6

5

8b

9

10

I

III IVa VVI

VII VIIIII

IXIVbX

XI

XII

II-III

N

Penetration depth (cm)

x (m)

y (m)MF

II

scarpPreP map of the study area

Danube

36

30

24

18

12

6

0

Danube

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70

-31

-28

-25

-22

-19

-16

-13

-10

-7

Distance (m)

Pene

trati

on d

epth

(cm

)

MF

S8

S12

S16

S20

P1

N6

S4

S6

S10

S18

N4N2

N0

S2

S14P2 N

P2 profile PreP result

active side passive side

River Danube

Vár hill

street

hill edge

Buildings at the bottom of the Vár hill

S8

S12

S16

S20

P1

N6

S4

S6

S10

S18

N4N2

N0

S2

S14P2

MF1.5-2 m

0.6-1 m

W

E

New mass movement (summer 2015)

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70

-31

-28

-25

-22

-19

-16

-13

-10

-7

Distance (m)

Pene

trati

on d

epth

(cm

)

MF1

Newly developed fractures

MF2

Danube

Verification of the results 1.

P2

S8S12S16S20

P1

N6

S4

S6

S10

S18

N4N2

N0S2

S14

P2 N

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

-31-28-25-22-19-16-13-10

-7

Distance (m)

Pene

trati

on d

epth

(cm

)

MF

forecasted and realised

forecasted but not (yet ?) realised

???

Verification of the results 2.

Danube

P1

S8

S12S16S20

P1

N6

S4

S6

S10

S18

N4N2

N0S2

S14

P2

N

Conclusions 1- A new method, the Pressure Probe (PreP) method has been developed which

- is easy to use;- is cost effective;- is applicable also in areas which are difficult to reach;- has very good resolution (2 cm wide fractures are detectable);- provides easily interpretable results;

- can e.g. localise fractures very precisely.

Its applicability is limitedif the mechanical properties of the soil are exposed to artificial changes, e.g. in agricultural areas, or in areas visited by vehicles.

Conclusions 2.Using the Pre-P method the fracture system of a slowly-moving landslide could have been mapped. It was shown that:

- Even very thin cracks are detectable by this method.- There are signigficant fractures also in the still passive side

of the landslide; but their distances are about two times smaller than the distances of the fractures in the active side of the landslide;

- A well-consolidated zone is attached to the fractures on the side towards the edge of the hill;

- The southern part of the study area is less endangered than the northern one.

The Pre-P method enables the delineation of such landslides and most likely also the prediction of future rupture surfaces.

Thank you for your attention!

Danube, the guilty