Journal of Rock Mechanics and Geotechnical Engineering. 2012, 4 (4): 326–332

Design and verification of portable direct shear tester with application to remolded colluvium geomaterials

K. J. Shou, Y. W. Lin

Department of Civil Engineering, National Chung-Hsing University, Taichung, Taiwan 40227, China Received 10 January 2012; received in revised form 12 June 2012; accepted 10 July 2012

Abstract: The mechanical properties of colluvium strongly govern the stability of colluvial slopes, and they are essential for the related analysis and design. Nevertheless, their measurement is not easy on account of heterogeneity in property and difficulty of sampling. This study attempted to evaluate the shear strength of remolded colluvium by means of a simple direct shear test in the field. A portable direct shear tester was designed to overcome the inconvenience and expensiveness of the conventional large-scale in-situ direct shear test. It can be easily assembled and applied for the simple field direct shear test. For calibration, the results of the portable direct shear tester were compared with the results of the laboratory direct shear tester for four different types of soil samples, i.e. standard sand, slate debris, arenaceous shale debris and mixture of gravel and sand. Correlation formulas were established based on the calibration, enabling the portable direct shear tester to measure and estimate the shear strength of remolded colluvium in field. This study primarily focuses on the colluvium in Central Taiwan, including the lateritic Dadu Terrace and the arenaceous shale of Taiping-Wufeng mounts. The portable direct shear tester was applied to sites selected in these areas, and the results were further analyzed and discussed. Key words: direct shear test; portable direct shear tester; simple field direct shear test; colluvial slope

1 Introduction

As a result of intensive impacts of earthquakes and heavy rains, landslide frequently occurs in Central Western Taiwan. The landslides could be either newly initiated or reactivated, but the generation of colluvial slopes is inevitable. Therefore, the stability of slopes characterized by colluvium is always a major challenge to engineers and government authorities. For the analysis and design of a colluvial slope, the shear strength of composing colluvium is one of the most important characteristics (Hamel and Flint, 1972; Skempton, 1985; Fell et al., 2000; Karikari-Yeboah and Gyasi-Agyei, 2000; Stark et al., 2005).

The most common methods of measuring shear strength include the laboratory direct shear test and triaxial test. But those laboratory tests need field sampling which might not be easy for the geomaterials like colluvium. For a direct shear test, scale effect of the shear box can be critical to test results, and it is

Doi: 10.3724/SP.J.1235.2012.00326 Corresponding author. Tel: +886-4-2287-2221 ext. 240; E-mail: kjshou@dragon.nchu.edu.tw

also affected by relative density and type of geomaterial (Cerato and Lutenegger, 2006). In general, larger shear boxes and careful sample preparation are the key factors for a successful direct shear test. To avoid the disturbance of sampling, the large-scale in-situ direct shear test is a good alternative, but it is highly time-consuming and expensive. It requires heavy-duty machineries to prepare and perform the test, which is not easy especially in steep terrain and colluvial slopes with limited testing space (Marsal, 1969; Skempton, 1985; Matsuoka and Liu, 1998; Kakuo et al., 2001; Matsuoka et al., 2001; ASTM D3080-04, 2003; Liu et al., 2005; Yu et al., 2006).

To overcome the above disadvantages, this study designed a portable direct shear tester to tackle the inconvenience of the large-scale in-situ direct shear test. The major difference between these two methods is the amount of effort required to perform a test. For the portable direct shear tester, it takes only about 10 minutes to assemble or disassemble the tester, 30 minutes to test a colluvium sample; therefore it is more efficient and less expensive. It was designed based on the mechanism that upper shear box slides upon the lower shear box as the carrying platform was tilted (Lopes et al., 2001; Briancon et al., 2002; Narejo, 2003).

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Formulas were established to correlate internal friction angles measured by laboratory direct shear testers and the simple field direct shear tester, enabling the portable direct shear tester to accurately measure the shear strength of remolded colluvium on site. 2 Methodology

The Western Foothill of Taiwan comprises the Mushan, Guichulin, Chinshui, Cholan, and Toukashan sedimentary formations. Except Toukashan formation, those formations are mainly composed of arenaceous shale. This study focuses on the middle section of Western Foothill, including Houli Terrace, Dadu Terrace, and Taiping-Wufeng piedmont area (Central Geology Survey, 2003). As a deposit of debris transported from upper slope face by gravity, colluvium generally possesses the properties characterized by weak cementation, high porosity and low strength. Therefore, it is more vulnerable to human activity, earthquake and heavy rain, and this characteristic contributes to the landslide-prone behavior of colluvium-distributed areas. This behavior was widely observed in Central Western Taiwan because a tremendous number of landslides were induced by the 1999 Chi-Chi earthquake (Lin et al., 2003; Chen, 2005).

This study aims to develop a portable direct shear tester for the testing of colluvial geomaterial. In addition, the portable direct shear tester only requires limited testing space, i.e. approximately 1.0 m by 1.5 m, and that makes the developed tester more applicable to colluvial slopes. The developed tester was calibrated before applied to the colluvial slopes in Central Western Taiwan. This study comprises two major parts described as follows. 2.1 Calibration of the portable direct shear tester

For calibration, the test results from the developed tester were compared with those obtained from other laboratory direct shear testers, and correlation formulas were established subsequently. To investigate the robustness of the tester, this study adopted four different types of colluvium-like samples, including standard sand, mixture of 50% gravel and 50% sand, slate debris and arenaceous shale debris. The linear regression methods were applied to correlating the results of the portable direct shear tester and those of laboratory direct shear testers. The laboratory direct shear testers applied in this study are the small direct shear tester (with 63.5 mm cylindrical shear box) for standard sand, and the large-scale direct shear tester (with 50 cm by 50 cm rectangular shear box) for the

other three samples. 2.2 Application of the portable direct shear tester

Aerial photos of Houli Terrace, Dadu Terrace, and Taiping-Wufeng piedmont area were reviewed to find potential distributions of colluvial slopes. It was followed by field investigations to confirm the colluvium distribution and collect various slope characteristics. There are two types of colluviums in the study area, i.e. lateritic colluvium and arenaceous shale colluvium. In order to obtain the representative shear strength of those colluvium materials, test sites representing different types of materials were carefully selected according to the geologic map. To reduce the influence of water content, the tests were all performed in dry season during November to January. 3 The portable direct shear tester

The laboratory direct shear testers are commonly used to obtain the shear strength of geomaterials (Taylor, 1948; Skempton and Bishop, 1950; Matsuoka and Liu, 1998). The mechanisms of those testers are similar, i.e. the geomaterial in the shear box was sheared along a shear plane by the shear force applied to the box. The shear box can be as large as 50 cm by 50 cm to accommodate the size effect if the sample possesses larger size particles. In general, a direct shear tester adopts a level loading system to provide normal stress. To avoid inclination of the upper box due to differential vertical deformation in shearing, the end of pressure rod is designed as a ball against a concaved round hole in the top plate. The capacity of the tester is defined by the jack providing the shear force, which can be controlled by a servo-controlled system. 3.1 Components and setup

The portable direct shear tester (Fig. 1) contains the following components:

(1) Inclinable platform: carries the shear boxes. It can be inclined by manually hydraulic jack to induce sliding of the upper shear box.

(2) Shear box: is 50 cm long, 50 cm wide and 40 cm high, i.e. 20 cm high for both upper and lower halves. The lower shear box is fixed to the inclinable platform. The upper half can be either freely to slide or fastened by screws to change the clearance between upper and lower boxes.

(3) Slide rail: is attached on an inclinable platform. It is connected with four rollers of the upper shear box.

(4) Hydraulic jack: holds slide bracket on the base frame so that it slides to lift the inclinable platform. It

328 K. J. Shou et al. / J Rock Mech Geotech Eng. 2012, 4 (4): 326–332

(a) The picture of the assembled portable direct shear tester.

(b) The composition of the portable direct shear tester.

Fig. 1 Illustration of portable direct shear tester. The shear boxes can be raised and tilted by the jack on the base frame, and the upper shear box can slide down and shear the sample. can also adjust lifting rate and inclining rate of the platform by regulating the frequency of jacking stroke.

(5) Slide bracket: is built on the base frame. It supports the upper inclinable platform by the support force from hydraulic jack.

(6) Base frame: is the lower part of the tester. It possesses four protruding feet at four corners to prevent the tester from being overturned by the inclined shear boxes.

(7) Load iron plates: are used to apply a normal load on a test sample. The iron plates will be placed upon the upper shear box and slide together with the upper shear box. This tester can take up to 15 iron plates (150 kg in mass) which are equivalent to approximately 30 cm thick superficial soil stratum.

(8) Digital protractor: is used to measure the inclined angle of the shear box carrying platform at failure. The accuracy of the applied digital protractor is 0.01 for an inclined angle less than 10, and 0.1 for an inclined angle larger than 10.

3.2 Test procedures for the simple field direct shear tester

(1) Collect the colluvium from the bottom of colluvial slope. In order to avoid the influence of heterogeneity in vertical direction, a 50 cm by 50 cm by 40 cm pit is dug to obtain the colluvial material.

(2) Mix the colluvial material thoroughly after being screened by a 50 mm sieve, and then deposit the colluvial material evenly into the shear box.

(3) To consider the influence of compactness, the original colluvial slope surface and the re-compacted sample in the shear box are tested by a pocket penetrometer. To compact the sample comparable to the original state, the penetrometer reading of the re-compacted sample is matched with the reading of the original colluvial slope surface.

(4) Place one iron plate above the re-compacted colluvium sample. To apply the vertical load in a more uniform way, level is used to check the flatness of the iron plate.

(5) Loose the four screws at both sides of the upper shear box in contact with slide rails, and then adjust the clearance (20 mm is adopted in this study) between upper and lower shear boxes by the bolts and washers at both sides of the upper shear box.

(6) Add more iron plates according to the designated normal load and use level to recheck the flatness of upper face. The edges of the iron plates are lubricated in order to avoid the friction that might induce non-uniform vertical load during the inclining of shear box carrying frame.

(7) Use the hydraulic jack to lift the inclined platform. The lifting rate is controlled by counting the strokes in a period according to angle change rate (adapted to 3 per minute in this study).

(8) Due to inclining of the platform, sample in the shear box will experience increasing shearing force until a shear plane is generated by the sliding of the upper shear box. Then digital protractor is used to measure the inclined angle of platform at sliding failure.

It is recommended to prepare new colluvium samples for four different normal loads, i.e. repeating all the above eight steps. However, it could be acceptable to reuse the sample, i.e. repeating steps (2)(8), if the material is difficult to obtain. Besides, there is a limit of particle size on account of size effect, one tenth of the size of the shear box, i.e. 50 mm in our case, is suggested as the limit for the designed tester (Cerato and Lutenegger, 2006). 3.3 Analysis of the test data

The shear force of the developed tester is induced by

Normal force

Lower shear box

Shear box raised by jack

Jack

Upper shear box

50 cm

20 cm

K. J. Shou et al. / J Rock Mech Geotech Eng. 2012, 4 (4): 326–332 329

the inclining of the platform, and the origin of the shear force is the iron plates placed above the sample. When the shear force is increased by further inclining the platform, the normal load will be diminished simultaneously. The relationship between inclined angle of the platform and normal stress on the shearing plane n can be expressed as

n in

cosF NWA A

(1)

where nF is the normal force, N is the total number of iron plates applied, iW is the weight of one iron plate, and A is the size of the shear plane (2 500 cm2 for the developed portable direct shear tester). We also have

s is

sinF NWA A

(2)

where sF is the shear force. The n and s obtained by Eqs. (1) and (2) are

used to plot n - s curve to obtain the internal friction angle and cohesion c. 4 Results of calibration

To calibrate the portable direct shear tester, test results of this tester were compared with laboratory results of the small- and large-scale direct shear testers. Four colluvium-like samples, i.e. standard sand, slate debris, arenaceous shale debris and mixture of gravel and sand, were tested. 4.1 Test results

Standard sand samples were tested by the portable direct shear tester and the small-scale direct shear test with 63.5 mm cylindrical shear box. The internal friction angle of standard sand measured by the small-scale direct shear tester is 24.40, but cohesion was extremely low. Alternatively, the internal friction angle measured by the portable direct shear tester is 28.26, as shown in Fig. 2.

Fig. 2 Comparison of direct shear test results of sand (s.d.s. represents simple field direct shear test, d.s. represents conventional laboratory direct shear test).

Samples consist of 50% gravel and 50% sand, and are used as an artificial colluvium. Four different normal loads, i.e. 0.5, 0.8, 1.2 and 1.5 kN were applied by a certain number of iron plates. However, the normal stress for the portable direct shear tester must be defined by the inclined angle of platform at failure. As shown in Fig. 3, the internal friction angles obtained by the portable direct shear tester and laboratory large-scale direct shear test are 41.43 and 36.31, respectively. In addition, slate debris samples obtained from Lishan landslide area (Shou and Chen, 2005) were also tested by the portable direct shear tester and the laboratory large-scale direct shear tester. The portable direct shear tester gives an internal friction angle of 29.23 and a value of cohesion of 0.56 kPa. With a slight discrepancy, the laboratory large-scale direct shear tester gives an internal friction angle of 27.35 and a value of cohesion of 0.90 kPa (see Fig. 4).

Fig. 3 Comparison of direct shear test results of mixture of gravel and sand (abbreviations s.d.s. and d.s. defined in Fig. 2).

Fig. 4 Comparison of direct shear test results of slate debris (abbreviations s.d.s. and d.s. defined in Fig. 2).

Two sets of arenaceous shale colluvium samples were collected from Wufeng, i.e. the set of Cholan formation and the set of Siangshan phase of Toukashan formation. Similarly, these two sets of samples were tested by the two testers with four different normal loads as well. For the former set of samples, the portable direct shear tester gives an internal friction angle of 28.87 and a value of cohesion of 1.13 kPa. In addition, the laboratory large-scale direct shear tester gives an internal friction angle of 28.51 and a value of

s.d.s. =28.26, c=0.01 kPa

d.s. =24.40, c=0.05 kPa

0

1

2

3

4

0 1 2 3 4 5 6 7 8 Normal stress (kPa)

Shea

r stre

ss (k

Pa)

s.d.s. =41.43, c=0.01 kPa

d.s. =36.31, c=0.78 kPa

0

1

2

3

4

5

6

7

0 1 2 3 4 5 6 7 Normal stress (kPa)

Shea

r stre

ss (k

Pa)

d.s. =27.35°, c=0.90 kPa

s.d.s. =29.23°, c=0.56 kPa

0

1

2

3

4

5

0 1 2 3 4 5 6 7 8 Normal stress (kPa)

Shea

r stre

ss (k

Pa)

330 K. J. Shou et al. / J Rock Mech Geotech Eng. 2012, 4 (4): 326–332

cohesion of 1.73 kPa, as shown in Fig. 5. For the later set of samples, an internal friction angle of 26.80 and a value of cohesion of 1.07 kPa were found by the portable direct shear tester, and an internal friction angle of 24.15 and value of cohesion of 3.08 kPa were obtained by laboratory large-scale direct shear tester (see Fig. 6).

Fig. 5 Comparison of direct shear test results of Cholan formation arenaceous shale colluvium (abbreviations s.d.s. and d.s. defined in Fig. 2).

Fig. 6 Comparison of direct shear test results of Toukashan formation arenaceous shale colluvium (abbreviations s.d.s. and d.s. defined in Fig. 2).

4.2 Correlation formulas

Correlation formulas were established for internal friction angles measured by the portable direct shear tester and laboratory direct shear testers. Based on the results of five samples, linear regression can be applied to obtain the correlation formula as shown in Fig. 7. For simplicity, the relation was ideally set to cross the origin of the coordinates. This linear regression obtains the correlation of internal friction angles as =0.907 (3)

Fig. 7 Linear correlations for internal friction angles from the simple field direct shear test and laboratory direct shear test.

where θ denotes the internal friction angle measured by the portable direct shear tester and denotes the internal friction angle obtained by the laboratory direct shear testers. The coefficient of determination (R2) is 0.91 for this fitting line.

Allowing the relationship line to intercept a coordinate axis, the linear regression gives the relation:

0.797 3.502 (4) The coefficient of determination (R2) for this fitting

line is 0.92. The reasonably good R2 values show that both formulas express good correlation of θ and . 4.3 Discussion of results

The results in Figs. 26 show that internal friction angles measured by portable direct shear tester are 12%15% larger than those measured by small- or large-scale direct shear testers in the laboratory. It is also worth noting that the internal friction angle and residual shear angle tend to be larger than the theoretical minimum if the sample is sheared under lower normal stress (Brandl, 2000). Because the normal loads were deducted by the inclining of platform, the normal stresses for the portable direct shear tester are smaller than those for the laboratory direct shear testers (see Figs. 26). It might be the reason that the portable direct shear tester slightly overestimates the internal friction angle.

The correlation between the portable direct shear test and the laboratory direct shear test was based on the tests of only four different types of colluvium-like geomaterials. Therefore, the correlation might have an application limitation of the internal friction angle. To have more accurate correlation, the calibration for geomaterials with strength in other ranges is necessary.

In addition, cohesions measured by portable direct shear tester are much smaller than those measured by small- or large-scale direct shear tester. As the adopted colluvium-like geomaterials possess relatively lower cohesion, it is difficult to have accurate measurements of cohesion. Thus more test data, especially for those geomaterials with higher cohesion, are necessary to further investigate this discrepancy. 5 Applications

The portable direct shear tester was applied to the study of colluvium in Central Taiwan. The tests were performed in the eight sites selected in: (1) four sites in the lateritic formation, (2) two sites in the Cholan formation, and (3) two sites in the Siangshan phase of Toukashan formation.

Table 1 shows particle size distribution of lateritic material in the study area, which contains gravels

d.s. =28.51°, c=1.73 kPa

s.d.s. =28.87°, c=1.13 kPa

0

1

2

3

4

5

6

0 1 2 3 4 5 6 7 Normal stress (kPa)

Shea

r stre

ss (k

Pa)

d.s. =24.15°, c=3.08 kPa

0 1

2 3

4 5

6 7

0 1 2 3 4 5 6 7 Normal stress (kPa)

Shea

r stre

ss (k

Pa)

s.d.s. =26.80°, c=1.07 kPa

Internal friction angle θ (°)

Inte

rnal

fric

tion

angl

e δ

(°)

δ=0.907θ, R2=0.91

δ=0.797θ+3.502, R2=0.92

0

10

20

30

40

0 5 10 15 20 25 30 35 40 45

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(coarse) and lateritic soil (fine). The lateritic formation is composed of reddish brown clayey soil as cementation between gravels, and their physical properties vary dramatically. It reveals from Table 1 that the gravel content is 78%86%. As the maximum particle size (Dmax) is around 15 cm, to avoid removing too much large size gravels, we screen the geomaterial by a 76 mm sieve instead of the 50 mm one. Table 2 shows particle size distribution of samples collected in two sites in Cholan formation and two sites in Toukashan formation. The Cc, Cu values in Table 2 also reveal that the particle size of Toukashan formation is more uniform than the particle size of Cholan formation.

Table 1 Characteristics of lateritic colluvium in the study area.

Size distribution Site Dry unit weight (g/cm3) Gravel (%) Sand (%) Silt (%)

Houli Terrace/south 2.18 84 13 3 Dadu Terrace/north 1 2.09 78 17 5 Dadu Terrace/north 2 2.14 81 13 6

Dadu Terrace/west 2.32 86 10 4

Table 2 Characteristics of arenaceous shale colluvium in the study area.

Site d (g/cm3)

D10 (mm)

D30 (mm)

D60 (mm) Cc Cu

Sand (%)

Silt (%)

Cholan Formation/ Wufong 1.57 0.02 0.14 0.21 4.67 10.5 79 21

Cholan Formation/Taiping 1.59 0.042 0.18 0.23 3.35 5.48 86 14

Toukashan Formation/

Siangshan Phase/ Wufong

1.53 0.086 0.16 0.27 1.10 3.14 88 12

Toukashan Formation/

Siangshan Phase/ Taiping

1.52 0.062 0.18 0.28 1.87 4.52 92 8

The results of the simple field direct shear tests

performed by the portable direct shear tester are summarized and discussed below:

(1) The internal friction angles and cohesions of gravel colluvium measured by the portable direct shear tester were 4048 and 01.35 kPa, respectively, and the internal friction angles obtained by the correlation formulas ranged from 35.4 to 43.6 (see Table 3). These results show more gravel in the sample will give larger internal friction angle. Also the range of the test results reasonably includes the internal friction angle of 37 obtained by a large-scale in-situ direct shear test in this area (Lin, 2006).

(2) The internal friction angles and the cohesions of Cholan formation colluvium in Taiping and Wufeng were 28.87°39.90° and 0.21.4 kPa, respectively (as shown in Table 3). For the Siangshan phase of Toukashan formation, the results in Table 3 show the internal friction angles of 22.16°26.80° and cohesion

Table 3 Results of simple field direct shear tests in the study area by the portable direct shear tester.

Internal friction angle() Area Site Cohesion c (kPa) s.d.s.* Eq. (3)** Eq. (4)**

Houli Terrace/ south 0.02 48.05 43.58 41.8 Dadu Terrace/north 1 1.3 40.05 36.32 35.42 Dadu Terrace/north 2 0.2 46.08 41.79 40.23

Lateritic gravel area

Dadu Terrace/west 1.4 47.69 43.25 41.51 Cholan

Formation/Wufong 1.4 28.87 26.19 26.51

Cholan Formation/Taiping 0.2 39.9 36.19 35.3

Toukashan Formation/Siangshan

Phase/ Wufong 1.1 26.8 24.31 24.86

Arenaceous shale area

Toukashan Formation/Siangshan

Phase/ Taiping 1.8 22.16 20.1 21.16

Note: “*” means simple field direct shear test by the portable direct shear

tester; “**” means to introduce s.d.s. results into Eq. (3) or Eq. (4).

of 1.11.8 kPa, respectively. The results show that internal friction angles are lower in the more uniform Toukashan formation.

(3) According to a literature review of 6 large-scale direct shear tests (Lin, 2006), the internal friction angle of arenaceous shale in Western Taiwan is in a range of 16°37°, lower than the range 22°40° obtained by the portable direct shear tester in this study. However, it shows a closer approximation for the internal friction angle of 20.1°36.2° regulated by the correlation formulas.

6 Conclusions and suggestions

In this study, a portable direct shear tester was designed to tackle the inconvenience and expensiveness of the conventional large-scale in-situ direct shear test. It can be easily assembled and applied for the simple field direct shear test. For the colluvium in Central Taiwan, based on the comparison between test results in this paper and those from laboratory direct shear tests, the linear correlation formulas, i.e. Eqs. (3) and (4), were established. The test results in the field indicate that the portable direct shear tester can reasonably estimate the internal friction angle of remolded colluvium.

The study also illustrates the benefits of the portable direct shear tester, including easy to use, very efficient, and less expensive. Although the normal stress might be disturbed during the inclining and sliding of the shear box, this tester is reasonably good to gain the peak shear resistance (Lopes et al., 2001; Narejo, 2003), in which we carefully prepare the sample and properly perform the test.

Since there is no loading frame to provide reaction force, the normal load can be only applied by

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deadweight. And the normal load reduces when the upper shear box inclines. The limitation of normal load makes more inaccuracy from other sources, such as the friction between tester components and the uneven shear plane. More investigation on the derivation of the formulas, especially the part of normal stress, is strongly suggested. More tests are necessary to improve the accuracy of the correlation formulas and further investigate the discrepancy of cohesion. However, it is worthy to further improve the portable direct shear tester to overcome its shortcomings in loading and controlling mechanism. More properly applying the normal load, increasing the capacity of normal load, and more precisely controlling the rate of lifting are suggested for the further development of this tester. Acknowledgements

The work presented in this paper was made possible through the support of the National Science Council (NSC94-2211-E-005-022), Taiwan, China. The authors are indebted to the suggestions of the anonymous reviewers and the support of Profs. J. R. Lai and P. S. Lin.

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Keh-Jian Shou (Professor, Ph.D., Department Head) is now working with Department of Civil Engineering, National Chung-Hsing University, Taiwan, China (since 1994). He got his Ph.D. degree (Civil Engineering) from University of Minnesota, U.S.A. (1993).

His experience includes: (1) Senior Principal Engineer, Shannon & Wilson, Seattle, USA (2008/2–2008/9); (2) Visiting Professor, TTC, Louisiana Technical University, USA (2006/1–2006/2); (3) Visiting Professor, RCUSS, Kobe University, Japan (2003/10–2004/3); (4) Research Engineer, CSIR/Miningtek, South Africa (1998/2–1999/1); (5) Geotechnical Engineer, National Expressway Engineering Bureau, Taiwan (1993–1994). His major interests include rock mechanics, rock engineering, engineering geology, trenchless technologies, and geotechnical engineering. Contact information: Department of Civil and Environmental Engineering National Chung-Hsing University No. 250, Kuo Kuang Road, Taichung, Taiwan 40227, China Tel: (886) 4-2287-2221#240 Fax: (999) 4-2286-2857 E-mail: kjshou@dragon.nchu.edu.tw