Pure Appl. Geophys. 169 (2012), 1205–1215 Ó 2011 Springer Basel AG DOI 10.1007/s00024-011-0394-z

Pure and Applied Geophysics

Physical and Mechanical Properties of Serpentinized Ultrabasic Rocks in NW Turkey C. KURTULUS,1 A. BOZKURT,2 and H. ENDES1 Abstract—Serpentinized ultrabasic rocks crop out at various places in the northwestern part of Turkey. They are the foundation rocks of some architecture and the ground under road bases in many areas. They are also frequently used for indoor work such as tables, shafts, pilasters, jambs for chimney pieces and ornaments of different kinds. Owing to their economic importance, in situ geophysical and geotechnical studies were conducted to determine their dynamic engineering parameters such as: P- and S-wave velocities, Poisson’s ratio, rigidity modulus, elasticity modulus, bulk modulus, natural period, safe bearing capacity, and bearing coefficient. Geophysical and geotechnical laboratory tests were performed on cylindrical specimens cored across and along the foliation planes: ultrasonic measurements of compressional pulse velocity (UPV), uniaxial compressive strength (UCS), point load index (Is(50)), and static elasticity modulus (Es); effective porosity (n), dry unit weight (DUW), and saturated unit weight (!s) sets of the rock specimens were determined. Finally, statistical correlations were performed by regression analysis to evaluate the relationships between UCS and Is(50), UPV, Es; UPV and Is(50), DUW, !s, n, and Es. Key words: Serpentine, UCS, Is(50), UPV, engineering properties.

1. Introduction The characterization of soil and rock conditions using geophysical surveys and geotechnical tests for determining near surface geology and dynamic properties is crucial for seismic design of architecture and urban planning. The characterization of ground conditions requires the knowledge of local geology, dynamic soil properties and seismic velocities that are used by many codes for ground type classification, and the rock mechanical properties, which are the most

important constituents in designing geological projects. Uniaxial compression strength (UCS) is widely used for the engineering classification of rocks determined in a laboratory test in accordance with the American Society for Testing and Materials (ASTM, 2010), and the International Society for Rock Mechanics (ISRM, 2007). The determination of UCS is difficult and time consuming and needs regularly shaped rock samples, as defined in standards. The point load strength (Is(50)) is an attractive alternative to the UCS because it can provide similar data at a lower cost. Although a large number of studies have been conducted to determine the engineering and mechanical properties for the purpose of site characterization and land use, only few of them have been performed on serpentinites (RAO and ROMANA, 1974; KOUMANTAKIS, 1982; PAVENTI et al., 1996; CHIRSTENSEN, 2004; COURTIER et al., 2004; MARINOS et al., 2006; DIAMANTIS et al., 2009). This paper presents the results of the geophysical surveys performed in the Ezine area (NW Turkey). In addition to the geophysical analyses, uniaxial compressive strength and point load strength index determined across and along the foliation planes of serpentinized ultrabasic rocks in the investigation area and their index properties such as dry and saturated unit weights, and effective porosity were determined. The static elasticity modulus was calculated across foliation planes of the specimens. The results were statistically analyzed using a simple regression method. The relationships among these properties were figured out by the best fit equations.

1

Department of Geophysical Engineering, Engineering Faculty, Kocaeli University, Umuttepe Campus, 41380 ˙Izmit/ Kocaeli, Turkey. E-mail: [email protected]; [email protected] 2 ABM Engineering Co, ˙Izmit/Kocaeli, Turkey. E-mail: [email protected]

2. Site Description The serpentinized rock specimens for this study were collected from the northeastern part of Ezine

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town, a hilly terrain crossed by roads. A total of 20 rock blocks, which were large and homogeneous enough to provide test specimens free from fractures, joints or partings, were collected and tested for this study (Fig. 1).

Figure 1 Geological map of investigation area and location of the geophysical applications and serpentinized ultrabasic rock specimen collecting points (general directorate of Mineral Research and Exploration, 2005)

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3. Geology of the Investigation Area Lower Miocene Ezine volcanites, Permian ophiolites, Triassic Kazdag massive, Pliocene– Pleistocene Bayramic formation and Holocene alluvium are observed in the investigation area (Fig. 1). Andesites, dacites, basalts, tuffs and agglomerates form the lower Miocene Ezine volcanites. These belong to the post-tectonic phase and are mainly of Tertiary age. To the east of Ezine, altered hornblendeandesites are found intermingled with tuffs and agglomerates (KALAFATCIOGLU, 1963). Permian ophiolites consist of serpentinized ultrabasic rocks (called Denizgo¨ren ophiolite by OKAY et al., 1990, and EZINE ophiolite by BILGIN, 1999), such as serpentinites, harzburgites, dunites, lherzolites and pyroxenites. The serpentinized ultrabasic rocks are exposed north of Ezine, in a N–S belt, 10 km long and 2–4 km wide. The unit is mainly composed of serpentinized peridotites, green, dark green and light brown in color (Fig. 2). The ophiolitic rocks occur on top of the other units with tectonic contact at the east-northeast of the study area. Olivine and pyroxene were transformed into serpentine minerals and the metamorphic reaction was accompanied by the disappearance of the textural and minerological characteristics of the protoliths. Serpentines are usually represented by sieve textured cyrisotiles (Fig. 3) (ARIK and AYDIN, 2011). The serpentinization percentage ranges from 25 to 39% (KO¨PRU¨BASI, 2007). Fractures and fissures of the highly fractured ophiolites were filled by secondary carbonates. Orthopyroxenes and opaque minerals are secondary components of these rocks. The age of the protoliths of the Denizgo¨ren ophiolites were interpreted as Paleozoic (BINGO¨L et al., 1973) and Permo-Triassic (OKAY et al., 1990). The age of metamorphism, evaluated in amphibolites at the base of the unit, was proposed to be 117 Ma (OKAY et al., 1996) or 125 Ma (BECELETTO and JENNY 2004). Accordingly, the Denizgo¨ren ophiolites formed in Permian–Triassic times and were metamorphosed and emplaced in the upper Cretaceous (ARIK and AYDIN, 2011). Kazdag metamorphites are observed in the northern part of the investigation area and comprise schists, migmatites, metagabbros, amphibolites, fillites, marbles and recrystallized limestones (TURGUT,

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Physical and Mechanical Properties of Serpentinized Ultrabasic Rocks in NW Turkey

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Figure 2 Serpentinized ultrabasic rocks exposed in the NW of Ezine town

Figure 3 Sieve texture serpentines in denizgo¨ren ophiolites a Parallel nikol, b cross nikol (Arik and Aydin, 2011)

2002). The Bayramic formation is exposed in northeast of Ezine and consists of gravel-gravely sandstone and siltstone. Finally, holocene alluvium is located to the east and north of Ezine and is formed of blockgravel-sand and clay.

4. Dynamic Engineering Properties Adequate knowledge of ground conditions is very important for analysis, design and construction of

foundations. A detailed site investigation is necessary to characterize the serpentinized ultrabasic rocks for design and construction of safe foundations. Several laboratory and field techniques are available to measure the dynamic properties. In this paper, the dynamic properties of serpentinized ultrabasic rocks were determined using geophysical techniques of seismic refraction and resistivity. The uniaxial compressive strength (UCS) is one of the key properties for characterization of rock materials in engineering practices. It is used to

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determine compressive strength of rock specimens. The procedure for measuring the UCS has been given by both (ISRM, 2007) and (ASTM, 2008a, b). The point load strength test (Is(50)), is used as an index test for strength classification of rock materials. This index can be used to estimate other rock strength parameters such as uniaxial strength, tri-axial strength, tensile strength, Schmidt hardness, elasticity modulus, P-wave velocity, and peak strength (TEPNARONG, 2007; HOEK and BROWN, 1980; MARINOS et al., 2006; MARINOS, and HOEK, 2001; GOKTAN and HYDAN, 1993; KAHRAMAN, 2001; FEDDOCK et al., 2003). Given that the UCS method is time consuming and expensive, other non-destructive testing of rock properties have always been attractive for being costeffective, time conserving and practical (DIAMANTIS et al., 2009; WIJK, 1980; CHAU and WONG, 1996; KAHRAMAN, 2001; KAHRAMAN et al.,2003; ZACOEB et al., 2006; TEPNARONG, 2007; GHOSH and SRIVASTAVA,1991). Many researchers have correlated ultrasonic pulse velocity (UPV) with porosity and density (MORGAN,1969; YOUASH, 1970; GARDNER et al.,1974; HAMILTON, 1978; CASTAGNA et al., 1985; CHAU et al., 1996; SHON, 1998; YAS¸AR and ERDOGAN, 2004; KAHRAMAN and YEKEN, 2008). D’ANDREA et al. (1964), CHAU and WONG (1996), CHARY et al. (2006) and KURTULUS et al. (2010a, b) conducted uniaxial compression and point load tests on several rocks and determined a good relation between UCS and Is(50).

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In this study direct determination of UCS, Is(50) and Es were conducted in order to determine the physical and mechanical properties of serpentinized ultrabasic rocks. The other properties such as porosity and density of the serpentine specimens were obtained in the laboratory.

5. Geophysical Survey The seismic refraction and resistivity surveys were conducted at five different locations (Fig. 1). The seismic data were recorded using a 12 channel Geometrics Seismic Enhancement (Smart Seis) seismograph. The first arrival picks (first breaks) were taken and tabulated. The time-distance graphs were plotted and the plotted points were best fitted. The seismic velocities were calculated from the slops of the fitted lines on the time-distance curve using the GeoSeis computer program (Fig. 4). The dynamic elastic properties of the layers were derived from these velocities using them in empirical equations (KURTULUS 2000, 2002; TEZCAN et al., 2007). The natural period of the ground was calculated using the GBV-316 model microtremor device. The calculated average P- and S-velocities and other dynamic properties are illustrated in Table 1, where, Vp and Vs are the P- and S-velocities, r is the Poisson’s ratio r = 1 - 2(Vs/Vp)2/(2 - 2(Vs/Vp)2); G is the rigidity

Figure 4 a P seismogram, b S seismograms recorded in the investigation area

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Table 1 Average dynamic P- and S-wave velocities and engineering properties of serpentines determined from seismic refraction survey in the investigation area

Average Standard deviation

Vp (m/sn)

Vs (m/sn)

UPW

r

G (GPa)

E (GPa)

k (kN/m3)

2,420 2,490 2,545 2,467 2,428 2,470 50.7

1,355 1,392 1,450 1,397 1,385 1,395.8 34.4

20.6 20.58 20.6 20.48 20.48 20.55 0.063

0.27 0.27 0.26 0.26 0.26 0.264 0.006

3.75 3.99 4.35 4.0 3.92 4.002 0.22

9.54 10.15 10.96 10.13 9.88 10.132 0.52

6.96E?08 7.44E?08 7.59E?08 7.15E?08 6.82E?08 7.20E?07 32166753

modulus G = (DUW).V2s /100; E is the elasticity modulus E = 2(1 ? r)G; k is the bulk modulus k = {2(1 ? r)/3(1 - 2r)}G; qS is the safety bearing capacity qs = 0.024 (DUW).Vs; Ks is the bearing coefficient Ks = 40 9 (Vp/Vs) 9 qS 9 19.99; DUW is the dry unit weight DUW = {(0.002 9 Vp) ? 16}/ 10, and T0 is the natural period.

6. Electrical Resistivity Survey The electrical resistivity method was used to delineate the resistivity of serpentinized ultrabasic rocks. The Vertical Electrical Sounding (VES) technique with the Schlumberger array system were adopted at five points within the site (Fig. 1). The total current electrode spacing (AB) was opened as much as 60 m. The VES field results are presented as depth sounding curves. Interpretation of the curves was achieved by the partial curves matching method and computer iteration. The resistivity values were determined between 290 and 315 Xm, which reflect the porous or fractured nature of the serpentinized ultrabasic rocks.

7. Geotechnical Studies 7.1. Experimental Procedure Twenty big rock blocks were sampled in the investigation area north of Ezine town (Fig. 1). Cylindrical specimens with length between 110 and 115 mm and diameter of 54 mm (ASTM, 2001, 2010; ISRM, 2007) were prepared for testing from

T0 (sn)

0.39

qS (kPa)

Ks (kN/m3)

665 687.5 719.8 688.4 679.6 688.06 20

71167.6 73725.4 75744.2 72882.6 71461.6 72996.28 1857

each specimen by drill coring along two orthogonal directions: across and along the foliation planes, that is, 20 specimens along foliation and 20 specimens across foliation were prepared for uniaxial compressive strength, and 20 specimens along foliation and 20 specimens across foliation were prepared for point load test. In addition, 20 specimens with the same size across foliation were prepared for the static elasticity modulus test (Fig. 5). The two ends of the specimens were ground and lapped parallel to accomplish an accuracy of ±0.2 mm and both end surfaces were polished. The cylindrical sides were made straight with an accuracy of ±0.3 mm over the full length of each specimen. The physical properties of the specimens such as dry unit weight, saturated unit weight, water absorption and effective porosity were determined in accordance with ISRM (2007). The tests were performed at room temperature in dry conditions. The effective porosity of rock specimens was determined using saturation and buoyancy techniques. All samples were saturated by water immersion for a period of 48 h with periodic agitation to remove trapped air. Later, the samples were transferred underwater to a basket in an immersion bath and their saturated-submerged weights were measured with a scale having 0.01 g accuracy. Then, the surface of the specimens was dried with a moist cloth and their saturated-surfacedry weights were measured outside water. Bulk sample volumes were found from weight differences between saturated-surface-dry weight and saturatedsubmerged weight. The dry mass of specimens was determined after oven drying at a temperature of 105°C for a period of at least 24 h. The effective pore volumes were determined from weight difference

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between saturated-surface-dry weight and dry sample weight. The uniaxial compressive str ength (UCS) of the specimens was determined by subjecting each specimen to incremental loading at a nearly constant rate with the help of a hydraulic testing machine of 150 kN capacity in accordance with ASTM (2010). The point load index (Is(50)) of each cylindrical specimen was determined by mounting each specimen between two pointed platens of a point load tester of 50 kN capacity in accordance with ASTM (2008). The static elasticity modulus test was performed by placing the each specimen in a loading device of 150 kN capacity, and recording the deformation of specimen under axial stress in accordance with ASTM (2002). The test results indicated that the static elasticity modulus values calculated from the stress–strain curve from uniaxial testing are much lower than dynamic elasticity modulus values (HELVATJOGLU-ANTONIADES et al., 2006; STAVROGIN et al., 1984). Ultrasonic pulse velocity (UPV) measurements of compressional waves (P-waves) were conducted using Pundit Plus and DT Quist-120t ultrasonic pulse generator instruments with the transducers having a 54 kHz frequency to compare the rates measured by them. UPV was measured on all serpentinized ultrabasic rock specimens prepared for Is(50), UCS and Es test with a diameter of 54 mm and a length 110–115 mm. The ends of the core specimens were polished and covered with stiffer grease to establish a good coupling. The measurements on each rock specimen with two instruments were conducted several times to test the accuracy of the measured velocities. The average value of ultrasonic pulse

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velocity (UPV) measurement results obtained from two instruments was considered. The test results revealed that compressional velocities along the foliation planes are always faster than those across the foliation planes for all specimens. This result shows that the foliation of the metamorphic rocks is the primary parameter causing anisotropy between

Table 2 Summary of results of dry and saturated unit weight, water absorption and effective porosity Sample no.

Dry unit weight. UPW (kN/m3)

Saturated unit weight cs (kN/m3)

Water absorption Wn (%)

Effective porosity (%)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Average Standard deviation

24.7 26.2 25.4 25.1 24.9 25.2 25.8 25.7 26.1 24.3 25.5 25.1 26.1 26 25.9 26.1 25.7 26.3 26.1 26.6 25.64 0.57

24.68 26.35 25.58 25.19 25.12 25.34 25.92 26.1 26.27 24.45 25.74 25.27 26.35 26.24 26.31 26.19 26.12 26.39 26.27 27.14 25.78 0.6

1.33 0.16 0.18 0.86 0.96 0.18 1.12 0.21 0.18 0.98 0.63 0.92 0.18 0.19 0.18 0.16 0.25 0.19 0.17 0.16 0.48 0.4

3.29 0.43 2.21 2.44 3.24 2.24 1.21 1.14 0.49 4.25 1.68 2.48 0.51 0.51 0.71 0.69 1.42 0.59 0.48 0.41 1.52 1.15

Figure 5 Preparation of cylindrical core specimens with respect to foliation planes

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Table 3 Wave velocities uniaxial compressive strength (UCS) and point load ındex (Is(50)) with respect to orientation of foliation Vp (across foliation) (m/s)

Vpa (along foliation) (m/s)

UCS (across foliation) (MPa)

Is(50) (across foliation) (MPa)

UCS (along foliation) (MPa)

Is(50) (along foliation) (MPa)

Static Elasticity Modulus (across foliation) (GPa)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Average Standard deviation

4110.3 5072.4 4927.8 4589.3 4310.31 4712.94 4752.6 4886.4 5111.3 4152.6 4889.5 4586.9 5240.2 5113.7 4957.2 5203.3 4800.2 4998.9 5112.6 5288.7 4840.9 336

4419.21 5471.83 5376.93 5047.79 4612.63 5085.26 5027.61 5287.96 5427.32 4463.69 5290.58 4931.24 5632.75 5502.37 5304.67 5576.32 5198.26 5364.77 5496.35 5376.93 5195 345

34.56 98.25 82.25 58.38 41.58 71.8 78.21 91.67 98.34 32.68 75.36 78.23 103.24 92.56 92.56 114.32 81.33 82.68 111.55 111.24 81.5 23.6

2.41 6.58 6.23 4.45 3.24 4.53 4.32 5.28 6.48 2.67 5.84 5.27 6.88 6.32 6.73 7.85 5.67 5.14 6.86 7.21 5.5 1.48

11.4 32.6 27.13 22.35 19.31 22.85 21.62 23.87 32.45 14.21 25.36 22.88 36.18 35.12 33.78 39.75 24.13 23.57 33.48 34.67 26.8 7.4

0.74 2.2 1.9 1.42 1.34 1.63 1.33 1.73 2.1 0.92 1.9 1.62 2.35 2.16 2.41 2.64 1.72 1.68 2.45 2.35 1.8 0.5

3.48 5.0 4.77 3.59 3.42 4.19 4.42 4.39 4.63 4.06 4.52 3.69 5.32 4.79 5.12 5.36 4.74 4.35 4.59 5.32 4.49 0.6

140 120 100 80 60 40 20 0

UCS = 15,248Is(50) - 2,2964

UCS (MPa)

UCS (MPa)

Specimen no.

2

R = 0,91

2

3

4 5 6 7 Point load index Is (50) (MPa)

8

9

45 40 35 30 25 20 15 10 5 0

UCS = 14,458Is (50 ) + 0,3852 2

R = 0,9565

0.5

1

1.5

2

2.5

3

Point load index Is (50) (MPa)

Figure 6 Scatter plot of UCS against Is(50) for cylindrical specimens with respect to a across foliation, b along foliation

two orthogonal directions (SONG et al., 2004; VASCONCELOS et al., 2007). The summary data of ultrasonic P-wave velocity and other index properties are presented in Table 2, whereas wave velocities, UCS, and (Is(50)) were illustrated in Table 3. 7.2. Statistical Analysis A regression analysis was performed to describe the relationships between UCS and Is(50), UCS and UPV, DUW and UPV, n and UPV, UCS and Es, and

Es and UPV. Hence, UCS data were plotted against Is(50) data (Fig. 6) and UPV (Fig. 7). Is(50) data were plotted against UPV data (Fig. 8), DUW data were plotted against UPV data (Fig. 9), n data were plotted against UPV data (Fig. 10), UCS data were plotted versus Es data (Fig. 11a), and Es data were plotted against UPV (Fig. 11b). These results were analyzed using least squares regression. It was determined that UCS increases with increase in the Is(50) (KURTULUS, 2010; D’ANDREA et al.,1964a, b; BROCH and FRANKLIN, 1972; BIENIAWSKI, 1975; HASSANI et al.,1980; READ et al.,1980; FORSTER, 1983;

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R = 0,9253

100

UCS (MPa)

UCS (MPa)

120

80 60 40 20 0 4000 4200 4400 4600 4800 5000 5200 5400

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45 40 UCS = 0,0188(UPV) - 71,054 R2 = 0,8316 35 30 25 20 15 10 5 0 4400 4600 4800 5000

5200

5400

5600

5800

Ultrasonic pulse velocity (UPV) (m/s)

Ultrasonic pulse velocity (UPV) (m/s)

9 8 Is(50) = 0,0042(UPV) - 14,602 7 2 R = 0,895 6 5 4 3 2 1 0 4000 4200 4400 4600 4800 5000 5200 5400

3 Is (50) = 0,0013(UPV) - 4,819

2.5

Is (50) (MPa)

Is (50) (MPa)

Figure 7 Scatter plot of UCS against UPV for cylindrical specimens with respect to a across foliation, b along foliation

R2 = 0,8383

2 1.5 1 0.5 0 4400

Ultrasonic pulse velocity (UPV) (m/s)

4600

4800

5000

5200

5400

5600

5800

Ultrasonic pulse velocity (UPV) (m/s)

3

Dry unit weight (DUW) (kN/m )

3

Dry unit weight (DUW) (kN/m )

Figure 8 Scatter plot of Is(50) against UPV for cylindrical specimens with respect to a across foliation, b along foliation

2.7 DUW = 0,0002(UPV) + 1,7752 R2 = 0,8786

2.65 2.6 2.55 2.5 2.45 2.4 4000

4200

4400

4600 4800

5000

5200

5400

Ultrasonic pulse velocity (UPV) (m/s)

2.7 2.65

DUW= 0,0001(UPV) + 1,7937 R2 = 0,8323

2.6 2.55 2.5 2.45 2.4 4400

4600

4800

5000

5200

5400

5600

5800

Ultrasonic pulse velocity (UPV) (m/s)

4.5 4 n= -0,0031(UPV) + 16,736 R2 = 0,8789 3.5 3 2.5 2 1.5 1 0.5 0 4000 4200 4400 4600 4800 5000 5200 5400

Ultrasonic pulse velocity (UPV) (m/s)

Effective porosity (n) %

Effective porosity (n) %

Figure 9 Scatter plot of dry unit weight (UPW) against UPV for cylindrical specimens with respect to a across foliation, b along foliation

4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 4400

n = -0,0029(UPV) + 16,373 R 2 = 0,8318

4600

4800

5000

5200

5400

5600

5800

Ultrasonic pulse velocity (UPV) (m/s)

Figure 10 Scatter plot of effective porosity against UPV for cylindrical specimens with respect to a across foliation, b along foliation

Physical and Mechanical Properties of Serpentinized Ultrabasic Rocks in NW Turkey

140 UCS = 36.029Es - 81.132 R2 = 0.7457

UCS (MPa)

120 100 80 60 40 20 0 3

3.5

4

4.5

5

5.5

Es (GPa)

Static Elasticity modulus (Es) MPa

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6 5 4 3 2

Es = 0.0015(UPV) - 2.516 R2 = 0.7462

1 0 4000 4200 4400 4600 4800 5000 5200 5400

Ultrasonic Pulse Velocity (UPV)

Figure 11 Scatter plot of uniaxial compressive strength (UCS) against static elasticity modulus (Es) (a), and Es against to ultrasonic pulse velocity (UPV)

Table 4

8. Discussion and Conclusions

Empirical relationship between UCS and Is(50) engineering properties and UPV, and Es and UCS, and UPV R2

Empirical relationships UCS = 15248Is(50) - 2.2964 UCS = 14.458Is(50) ? 0.3852 UCS = 0.0675(UPV) - 245.13 UCS = 0.0188(UPV) - 71.04 Is(50) = 0.0042(UPV) - 14.602 Is(50) = 0.0013(UPV) - 4.819 DUW = 0.0002(UPV) ? 1.7752 DUW = 0.0001(UPV) ? 1.7937 n = -0.0031(UPV) ? 16.736 n = -0.0029(UPV) ? 16.733 UCS = 36.029Es - 81.132 Es = 0.0015(UPV) - 2.516

Across foliation Along foliation Across foliation Along foliation Across foliation Along foliation Across foliation Along foliation Across foliation Along foliation Across foliation Across foliation

0.91 0.95 0.92 0.83 0.89 0.83 0.87 0.83 0.88 0.83 0.75 0.75

GUNSALLUS and KULHWAY,1984; CARGILL and SHAKO1990; CHAU and WONG, 1996). UPV increases with dry unit weight, while it decreases with porosity. The empirical relationships between the UCS and Is(50), UCS and UPV, dry unit weight (DUW) and effective porosity (n) and P-wave velocity, and static elasticity modulus and UCS and UPV are given in Table 4. According to Table 2, uniaxial compressive strength (UCS) and point load strength Is(50) and ultrasonic pulse velocity (UPV) showed strong linear correlations with the highest correlation coefficients (R2 = 91–95). Point load index Is(50) and UPV, dry unit weight (DUW) and UPV, and effective porosity (n) and UPV exhibited linear correlations with R2 equal to 89, 83, 87 and 83, respectively. Also, a nonlinear relation between UCS values and static elasticity modulus values (Es) was found. A good linear relation was determined between Es and UPV with R2 = 0.75.

OR,

The objective of the study was to determine the dynamic engineering values as well as the geotechnical and mechanical properties of serpentinized ultrabasic rocks. For this purpose, seismic and electrical surveys were conducted at five different locations and rock specimens were collected from 20 different points of the investigation area and subjected to tests. Average seismic P- and S-velocities were determined to be equal to 2,470 and 1,395.8 m/s, respectively. A comparison of data shows a reasonable consistency among Vp, UCS, Is(50), and static elasticity modulus (Table 3). The discrepancy increases notably when comparing Vp in situ values with laboratory results. The large reductions in Vp in situ values are clearly the functions of fractures and natural joints. Fracture frequencies are usually high for 5–10 m rock depth and Vp were strongly affected as a result. The Poisson’s ratio, the safety bearing capacity and other engineering parameters point out that serpentinized ultrabasic rocks are strong enough for being a foundation rock. The resistivity survey, that employed the vertical electrical sounding, shows in the study area moderate resistivity value ([180 Xm). The mechanical properties (UPV, UCS and Is(50)) of serpentinized ultrabasic rocks have been determined with laboratory tests. Static elasticity modulus (Es) was calculated for across foliated specimens. Certain physical parameters such as effective porosity (n), dry unit weight (DUW) and saturated unit weight (cs) were also determined. The collected data contribute to the geomechanical characterization of a wide extent of geological units subject to civil works

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and use as ornamental stone. Finally, statistical correlations were conducted by regression analysis to evaluate the relationships between compressive strength and Is(50), UCS, DUW, n and UPV, and empirical relations were determined between these parameters and UPV with the high correlation coefficients. In addition, Es was correlated with (UPV) and (UCS).

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(Received December 8, 2010, revised July 12, 2011, accepted July 13, 2011, Published online August 6, 2011)