stability assessment of the cut slopes in … finally stability assessment by bishop’s method to...

http://www.iaeme.com/IJCIET/index.asp 1628 [email protected]

International Journal of Civil Engineering and Technology (IJCIET) Volume 9, Issue 4, April 2018, pp. 1628–1639, Article ID: IJCIET_09_04_180 Available online at http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=9&IType=4 ISSN Print: 0976-6308 and ISSN Online: 0976-6316 © IAEME Publication Scopus Indexed

STABILITY ASSESSMENT OF THE CUT

SLOPES IN THE WIDIKUM HIGHLANDS OF

CAMEROON

O. R. M. Kenmoe

Department of Earth Sciences, Faculty of Science, University of Dschang, P.O Box 67 Dschang, Cameroon

V. Y. Katte

Department of Civil Engineering and Forestry Techniques, HTTTC, The University of Bamenda, P.O Box 39 Bambili, NWR, Cameroon

(Corresponding author)

A. S. L. Wouatong

Department of Earth Sciences, Faculty of Science, University of Dschang, P.O Box 67 Dschang, Cameroon

F. Ngapgue

Department of Civil Engineering FV UIT Bandjoun, University of Dschang Cameroon

ABSTRACT

Slope instability is a common phenomenon in highland regions of the world

leading to loss of life and property. In this study geotechnical studies were carried out

and finally stability assessment by Bishop’s method to obtain factors of safety and

critical heights of slopes for five sites within the Widikum highlands were carried out.

The results obtained are indicative of stable slopes with factors of safety greater than

1 for three sites and unstable slopes for two sites. The critical heights of the slope sites

are 2.3 m when the platforms do not carry a surcharge and 2.3 – 0.13q if the

platforms carry a surcharge. Therefore, serious protection procedures should be

carried out to mitigate frequent landslides within the study area.

Keywords: Slope instability, geotechnical studies, factor of safety, Bishop’s methods, Widikum highlands Cite this Article: O. R. M. Kenmoe, V. Y. Katte, A. S. L. Wouatong and F. Ngapgue, Stability Assessment of the Cut Slopes in the Widikum Highlands of Cameroon, International Journal of Civil Engineering and Technology, 9(4), 2018, pp. 1628–1639. http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=9&IType=4

O. R. M. Kenmoe, V. Y. Katte, A. S. L. Wouatong and F. Ngapgue


1. INTRODUCTION

Slope instability may be defined as the loss of resistance of an inclined surface by either sliding or collapse. This is a common phenomenon in the mountainous terrain with the triggering factors often being geometrical changes to landform, shocks and vibrations, a change in the water regime of the environment, loss of vegetation and weathering.

Interest in slope stability investigations have become important because of some hazards recorded such as that in Hong Kong 1972 where 7 people died, as well as in Australia where 18 persons were killed in 1999. In Nepal in 2015, a landslide buried several villages including Langtang with approximately 400 deaths. The case of the slip of Aab Bareek, which occurred on May 02, 2014 in the Badakhchan region in Afghanistan, give a report of 300 dead and 4000 people displaced. In Cameroon, the village of Kekem experienced a slide, on the night of October 20, 2007 killing one person and causing much damage. Apart from the loss of life there is enormous property damage causing communication problems, social and economic disruption and loss of productive life. In some countries the economic consequences have been registered such as the USA which is above $2 billion and Japan $4 billion. The 1999 debris flow in Venezuela which killed about 50000 people amounted to a loss of about $10 billion which was 10.2% of the GDP.

There have been several approaches aimed at estimating the stability of ground surfaces on either weathered or intact rock slopes. The stability of natural rock and cut rock slope can be obtained using the rock mass classification system first introduced by (Bieniawski, 1976, 1979). Bieniawski, 1973 first proposed this parameter for the design of tunnels, mine, dam and underground excavations. Currently various other systems have been proposed and adopted for evaluating the stability of rock mass slopes such as the rock mass strength (Selby 1980, Moore et al., 2009), slope mass rating (SMR) system (Romana, 1985). However among the multiplicity of approaches used in assessing rock stability, the commonly used is the SMR (Romana et al., 2001, 2003, 2005). Meanwhile soil slope stability assessment of overburden material which is completely weathered material has been carried out since 1936 with the development of the equilibrium method of ordinary slices (Fellenius, 1936), Bishop’s modified method (Bishop, 1955). The force equilibrium methods (Lowe and Karafiath, 1960), Spencer’s method (Spencer, 1967), Janbu’s generalized method of slices (Janbu, 1968) and Morgenstern and Price’s method (Morgenstern and Price, 1965). There exist also several limit element methods available in software packages. Earth slope stability calculations are important for many civil engineering applications such as the design of cut and fill slopes as well as for maintenance or remedy operations in natural slopes. Earth slopes that have a factor of safety greater than 1 are stable; however with a change in shape or the internal and external forces, the factor of safety may also change. The purpose of this study is to analyze the stability of the natural and cut slopes and recommend suitable protection or stabilization measures in an area where there is frequent sliding.

2. STUDY AREA

The Widikum highlands is located in the North West Region of Cameroon between latitudes 05°49'12'' and 05°54'12'' of the Northern Hemisphere and longitudes 09°42' 00'' to 09°50' 00'' East. It comprises the following (Fig.1) villages: Bajem, Befang and Bamben in the North, Widikum in the Center, Diche I in the South, Diche, Denku and Numba in the West and of Tiben and Numben in the East. The Widikum environs lies between two climatic types which are the humid tropical equatorial rainforest climate in the Mamfe basin and the dry savannah climate of the Bamenda highlands. The rainy season commences from mid-March to mid-November and the dry season from mid-November to mid-March. The two main rivers are the Momo and Man, which are tributaries of river Manyu (Fig.1). Of recent

Stability Assessment of the Cut Slopes in the Widikum Highlands of Cameroon


there has been the construction of a paved highway opening up avenues for movement along the Enugu-Bamenda corridor passing through the Widikum highlands. It is observed that landslide and rock falls are affecting movement and communication on the portion of the highway in the Widikum highlands. Given the high population in this area the degraded forest is continually being replaced with palm and the area has been noted for oil palm production and a trading center.

Figure 1 Location of study area

3. METHODS

3.1. Profiling

Soil profiling was carried out on the cut slopes resulting from road construction activities of each of five sites of study area namely Keunom Tiben, Ogwei Tiben, Ofen Tiben, Fifty One and Numba. Furthermore, macroscopic descriptions were performed on each soil profile followed by specimen test collection at the upper, median and lower assemblage, for geotechnical analysis.

3.2. Geotechnical analysis

The geotechnical characteristics (natural water content, Atterberg limit, triaxial shear, absolute density) were performed on specimen collected and sealed in plastic bags then transported to the National Civil Engineering Laboratory (LABOGENIE) of Yaounde (Cameroon). The natural water content was determined by drying in an oven at a temperature of 105°C and for a duration of 24 hours according to the French standard norm NF P 94-050, (1995). The liquid limit was determined using the Casagrande method while the plastic limit was carried out on rods of 10 cm length and about 3 mm of thickness according to the French standard norm NF P 94-051, (1993). The Atterberg limits were used to determine the



plasticity index of the studied materials. Thus, Ip = ωL - ωP where Ip is the plasticity index; ωL the liquid limit and ωP represents the plastic limit. The Absolute density was obtained when the volume measured excluded the pore volumes between particles within the bulk sample. It was determined using the pycnometer method according to the French standard Norm NF P 94-054, (1991). The dry density, the porosity, the void ratio and the saturation ratio were determined using the relationships between physical characteristics of soils. Finally, the triaxial shear tests CU were carried out according to French standard norm NF P 94-074, (1994) in order to enable the determination of the friction angle and the cohesion of a material. It was carried out in three stages: firstly the sample preparation and installation in a triaxial cell then followed by saturation and finally shearing. After shearing of the specimen, respective stress curve τmax = f (σmax) were established from which the friction angle and the cohesion of weathered products were obtained. The stability analysis was carried out using the Bishop 1955 method to calculate the various factors of safety for the loose weathered profiles.

With the Bishop method, a slip circle was established with the loose weathered material which was subsequently divided into a number of vertical stripes of the same width taking into consideration site specificities. The Bishop approach can be explained by making reference to figure 2 where AC is an arc of a circle representing a trial failure surface as presented by (Das, 1999).

Figure 2 Stability analyses by ordinary method of slices, (a) trial failure surface (b) forces acting on the nth slice. (Das, 1999)



Figure 3 Bishops simplified method of slices (a) forces acting on the nth slice (b) force polygon for equilibrium (Das, 1999).

The trial surface is divided into a number of vertical stripes. For analysis a typical slice (nth slice) is considered having a weight Wn is shown in Figure 3 (a)

Nr and Tr = normal and shear components of the reaction R

Pn and Pn+1 = normal forces acting on the sides of the slice

Tn and Tn+1 = shearing forces acting on the sides of the slice.

Now we consider that Pn-Pn+1 = ΔP and Tn –Tn+1 =ΔT

T� = N��tanϕ� � + ��∆Ln = N� ��

�� + ��∆�� 1

From figure 3(b) summing the forces in the vertical direction of the polygon of forces for the nth slice we obtain.

W� + ∆T = N�cosα� + #$%��

�� + ��∆�� & sinα� 2

Or

N� = (�)∆*+,�∆-�./�0�12

�3456)78�9�./�0�12

3

For equilibrium of the wedge ABC taking moments about O gives.

∑ W�rsinα��<=�<> = ∑ T�γ�<=

�<> 4

Where

T� = >��.

�c + σ�tanϕ�∆L� = >��.

�c∆L� + N�tanϕ� 5

Substituting equations (3) and (5) into equations (4) gives

FS4 =∑ ��D�)(��)∆*�� E

F0��GH�GE

∑ (�4I�5��GH�GE

6

Where

m5�� = cosα� + ��4I�5��.

7

For simplicity, if ΔT is taken as zero, then equation (6) becomes



FS4 =∑ ��D�)(�� E

F0��GH�GE

∑ (�4I�5��GH�GE

8

For cases of steady state seepage equation 8 is modified to the equation (9) below

FS4 =∑ K�∗D�)�(�+MD�N E

F0��GH�GE

∑ (�4I�5��GH�GE

9

It is observed that the term FSs appears on both sides of equation and therefore a trial and error procedure must be adopted to determine the value of FSs. The relevant parameters were obtained from each site after there were carefully obtained from hand drawings and introduced into an excel spreadsheet. The factors of safety were obtained after several trials. Finally the critical height step of slopes was determined according to Taylor-Biarez expression in (Philipponnat and Hubert, 1997) to determine the long term stability of the slopes by means of equation (10)

H�> = 2.67 �T tan �45° + �

X� 10

If the plate forms limited by a slope is intended to be subjected to uniformly distributed surchage q, the critical height of each step will be given according to the equation (11)

H�X = 2.67 �T tan �45° + �

X� − XZT 11

Where c is the cohesion, [ the unit weight of the soil and \ the friction angle of the soil in both equations 10 and 11 respectively

4. RESULTS AND DISCUSSION

4.1. Soil Profile Characteristics

The profile of the Keunom Tiben site presents two large distinct sets organized from the top towards the base in upper alloteritic and lower alloteritic quartz block sets. The 18 m thick upper alloteritic assemblage corresponds to horizon BC1 as given in Fig.4 and consists of two phases: the yellowish red matrix (2) and the whitish matrix (1). The yellowish red matrix (5YR5/8) is sandy clay with fine to medium lumpy structure. It is friable, porous and contains some roots. The yellowish red indurated elements (5YR5/8) are individualized in millimetric to decimeter gravel. The whitish matrix (2.5YR8/1) is compact, dense, with a massive structure. It consists of millimeter to decimeter quartz crystals. These crystals recall that of the underlying set and represent about 10% of the total volume of materials in the set. The lower alloteritic quartz block assembly is about 13 m thick and corresponds to the BC2 horizon. It consists of two phases: the yellowish to reddish matrix (3) and the whitish matrix (4). The yellowish matrix (10YR8/8) to reddish (2.5YR5/8) is a sand-clay material, with a polyhedral structure, friable and quite porous. The whitish matrix (2.5Y8/1) consists of quartz blocks of metric sizes. It is compact, dense and reminiscent of the quartzo feldspathic structure of mother rock. It represents about 25% of the total volume of materials in the set.



Figure 4 Soil profile of Keunom Tiben site. (1) whitish matrix. (2) yellowish red matrix. (3) yellowish to reddish matrix. (4) whitish matrix.

The profile of the Ogwei Tiben site presents two large distinct sets organized from the top towards the base in upper alloteritic and lower alloteritic with gneiss blocks as shown in Fig.5.The upper alloteritic complex of thickness 15 m corresponds to horizon BC1. It consists of two phases: the yellowish red matrix and the light gray matrix. The yellowish red matrix (7.5YR7/8) consists of a sandy-clayey material, with a fine to medium lumpy structure, is friable and slightly porous. It represents approximately 55% of the total volume of assemblage materials. The indurated elements consisting of yellowish red (7.5YR7/8) of millimetric to decimetric gravels which are present within the set. They represent about 1% of the total volume of materials. The light gray matrix (2.5Y7/1) (1) is a clay-textured material of sub-angular to prismatic structure. It is sticky, pasty and very porous. It represents about 40% of the total volume of materials. The lower alloteritic group with gneiss blocks has a thickness of about 10 m and thus corresponds to the BC2 horizon. It consists of two phases: the yellowish red matrix (3) and the whitish matrix (2). The yellowish red matrix (5YR5/8) is a sandy-clayey material with a compact structure and of little porosity. It represents approximately 80% of the volume of the materials of the set, with some roots present. The whitish matrix (5YR8/1) is a sticky and pasty material. It represents about 15% of the total volume of materials in the set.

Figure 5 Soil profile of Ogwei Tiben site. (1) light gray matrix. (2) whitish matrix. (3) yellowish red matrix.



The site of Ofen Tiben has two distinct sets organized from the top towards the base in upper alloteritic and lower alloteritic with granite blocks. The upper alloteritic set of thickness 20.5 m corresponds to the B horizon as shown in Fig. 6. It consists of three phases: the yellowish red matrix (1), the red matrix (2) and the yellow matrix. The yellowish red matrix (7.5YR7/8) is a clay-silty material with a prismatic structure, very friable and slightly porous. It has a fine particle size and represents about 45% of the volume of the materials of the set, with some fine roots present. The red matrix (10R4/8) is a clay-silty material with a prismatic structure. It is very friable, porous and having medium to fine grain sizes particle representing 50% of the volume of materials, containing some roots. The yellow matrix (2.5Y8/6) of millimetric size represents approximately 7% of the total volume of materials of the set.

The lower alloteritic unit with centimetric to metric granite blocks has a thickness of 22m and corresponds to horizon C. It consists of three phases: the red matrix (10R5/8), the yellowish brown matrix (10YR6/8) and the pale brown matrix (10YR8/3) (3) consisting of centimetric rounded streaks. These streaks represent approximately 10% of the total volume of the materials and recall the quartzo-feldspathic minerals of the mother rock. The lower alloteritic set is a clay-silty textured material, with rounded to prismatic structure. It is none porous, compact and has a medium to coarse grain size.

Figure 6 Soil profile of Ofen Tiben site. (1) yellowish red matrix. (2) red matrix. (3) pale brown matrix.

The soil profile of site Fifty One is shown in Fig.7 and has three distinct large sets from the top towards the base in upper lateritic, median alloteritic with basalt blocks, and lower isalteritic assemblage. The upper lateritic set of thickness 3.5 m, corresponds to horizon B. It consists of a single phase; the dark red matrix (10R3/6). This matrix is a sandy-clay material with a lumpy structure. It is slightly porous and contains some roots. These roots represent about 1% of the total volume of materials.

The median alloteritic assemblage with basalt blocks is described on a 65 ° dipping bench. This 35 m thick set corresponds to the BC horizon and consists of two phases: the dark red to brown gravelly matrix (1) and the basaltic matrix (2). The dark reddish (10R3/4) to brown (5YR3/4) gravelly matrix is a sandy-clayey material with a lumpy structure. It is friable and porous. The basaltic matrix (GLEY2-2.5/1) consists of centimetric to metric healthy rock blocks. These represent about 40% of the total volume of materials.

The lower isalteritic assemblage is described on a 60 ° dipping bench. It is about 3.8 m thick and corresponds to horizon C. It consists of two phases: the greyish matrix (3) and the greenish matrix. The greyish matrix (2.5Y7/1) is a sandy-clay material with a lamellar



structure. It is friable and porous, is deboned by stripping. The greenish matrix (GLEY1-2.5/1) consists of a clay material with a polyhedral structure. It is pasty and slightly porous.

Figure 7 Soil Profile of Fifty One site. (1) dark red to brown gravelly matrix. (2) basaltic matrix. (3) greyish matrix.

The Numba site has three distinct large sets organized from the top towards the base in upper lateritic, median alloteritic and isalteritic granite assemblage and is shown in Fig. 8.

The upper lateritic assemblage is described on a bench dipping 50 ° of thickness 7.5m, it corresponds to the B horizon. It is consists of two phases; the reddish matrix (1) and the yellowish matrix. The reddish matrix (10R5/8) is a sandy-clay material with a sub-angular to prismatic structure. It is friable and very slightly porous. Reddish indurated elements (10R5/8) of decimetric to centimetric sizes are present. The yellowish matrix (2.5Y7/8) consists of hardened elements of decimetric to centimetric size. It has a lumpy structure and represents about 12% of the total volume of materials in the set.

The median alloteritic assemblage is described on a 7.5 m berm, a bench of 1.5 m with a dip of 54 ° and of thickness 50 m. It corresponds to horizon BC and consists of three phases: the dark brown matrix (2), the black matrix and the whitish matrix. The dark brown matrix (7.5YR5/8) is a sandy-loamy material with fine to medium lumpy structure. It is slightly porous and very friable. Some roots are present. The indurated elements consist of dark brown centimetric rounded gravel (7.5YR5/8). These elements represent approximately 30% of the total volume of materials. The black (5Y2.5/1) and whitish (5YR8/1) matrix are sub-angular, with decimeter to centimeter size, representing between 10 to 15% of the total volume of materials. These matrices are reminiscent of the ferromagnesian and quartzo feldspathic minerals of the mother rock.

The isalteritic assemblage of solid granite is described on a 5 m berm, a bench of 4 m, dipping 52°. It has a thickness of approximately 22.5m and corresponds to horizon C. This set consists of three phases: the red pale matrix (3), the white pinkish matrix and the ferromagnesian matrix with granite block. The red pale matrix (10R6/4) is a silty-sandy material with a prismatic structure. It is porous and very friable, with medium to fine grain size. The pinkish white matrix (2.5YR8/2) is composed of decimetric to centimetric fine gravels of quartz. These chunks represent about 20% of the particles of the set. The ferromagnesian matrix (5Y2.5/1) with centimetric to metric granite blocks represents about 65% of the particles of the set.



Figure 8 Soil profile for Numba site. (1) reddish matrix. (2) dark brown matrix. (3) red pale matrix.

4.2. Landslide Characteristics

The results of the geotechnical characteristics obtained from each study are given in the Table 1, which also presents the factors of safety of each of the five sites. All the sites present soil material with poor geotechnical characteristics for roadwork in accordance with the AASHTO soil classification system but for site Fifty One. In terms of the stability, Keunom Tiben, Fifty One and Numba have factors of safety greater than one making then potentially stable. However since the stability factors are only slightly greater than 1 for site Fifty One and Numba, these stable sites may be termed marginally stable since they have the potential to slide if any of the triggering mechanism of rainfall or vibration becomes abnormal. Keunom Tiben site is noted for rockfalls which reaches the road’s surface and often cuts of traffic flow. The rock surfaces are well weathered with a thick covering. The cut slope at this locality is still very steep (46 – 58) which is greater than the friction angle of the soil, and therefore may have to experience recurrent incidences of rockfalls more often. Moreover, many cracks are present on the rocks favoring their fall by gravity. The Ogwei Tiben site presents characteristics of a well weathered soil and characterized with steep slopes. The slope stability factor of the site is less than one thus potentially unstable. Ofen Tiben site also has also a factor of safety less than one making it also potentially unstable.

However, the critical height steps of slopes obtained varies between 2.3 and 20.5m (table 1). So, there are less than natural slope heights (on average greater than 40m). This element has a great role in instability observed.

Table1 Characteristics of specific site. KT Keunom Tiben. OT Ogwei Tiben. OF Ofen Tiben. FO Fifty One and NU Numba

S/N Sites

Characteristics

Soil

classification Hc1 (m) Hc2 (m)

Γ (kN/m3) Φ (°) Θ (°) C (kN/m

2)

Slope

Height

(m)

FOS

1 KT 17.2 4.43 31 30 80 2.06 A-7-5(3) 7.3; 7; 8.7

2,3 – 0,13q 2 OT 18.0 16.32 28.0 29.4 25 0.84 A-7-5(4) 6.4; 16.7 3 OF 16.5 11.89 36.0 17.2 43 0.79 A-7-5(14) 3.6; 20.5; 3.5 4 FO 16.2 16.50 37.0 21.6 45 1.14 A-2-7(1) 2.3; 6.8 5 NU 16.4 24.2 42.0 34.6 83 1.07 A-7-5(5) 5.5; 9; 9.9



5. CONCLUSION AND RECOMMENDATIONS

The purpose of this study was to investigate the stability of the cut slopes of five sites along the highway in the Widikum highlands using the Bishop Method and propose suitable remediation methods in an area experiencing frequent slides. The factors of safety using the Bishop’s method reveal that the slopes are generally stable for three of the sites Keunom Tiben, Fifty One and Numba having factors of safety greater than 1 and the two unstable sites Ogwei Tiben and Ofen Tiben with respective factors of safety being 0.84 and 0.79. Since the area is located in a high rainfall region, the slopes are thus generally prone to failure. The Keunom Tiben site needs some remedial work carried out which entails netting the slope to prevent blocks from falling off the slope. Where much of the rock fractures are evident, some grouting can be carried out to stabilize the rocks and prevent their downward movement. The planting of trees especially eucalyptus as well as vertiva grass is recommended at all sites to facilitate the process of evaporation which will render the soil much drier and the roots will also reinforce the soil and thus reduce the incidences of soil slip. General slope remedial work would have to be carried out in the near future. Since the least height of the steps guarantees more safety and facilitates the execution of the work, the critical height value of the steps proposed on the basis of data of table 1 is of 2.3m when the platforms do not carry a surchage by mitigating for a bench of 3m. Moreover, adopt the dip angle of θ = 37.5°. However, if the platforms are intended to carry surchage when executing slope works, the critical height must be calculated using the expression (11) Hc2 = 2.3 – 0.13q. Furthermore, build retaining works. The current cut slope face is generally very steep and facilitates the land slide together with the triggering mechanisms of rainfall and vibration from moving traffic.

REFERENCES

[1] Bieniawski, Z T (1973). Engineering classification of jointed rock masses. Trans S Afr Inst Civ Eng 15(12):335–344.

[2] Bieniawski, Z T (1976). Rock mass classification in rock engineering. In: Bieniawski ZT (ed) Exploration for rock engineering, proceedings of the symposium expl. Rock Engineering, Johannesburg, pp 97–106.

[3] Bieniawski, Z T (1979). The Geomechanics classification in rock engineering applications. In:Proceedings ofthe 4th international congress rock mechanics, Montreux, Balkema, Rotterdam, vol 2. pp 41–48.

[4] Bieniawski, Z T (1989). Engineering rock mass classifications. Wiley, Chichester, p 251

[5] Bishop, A.W. (1955). The use of the slip circle in the stability analysis of earth slopes. Geotechnique, Vol.5 (1), pp.7-17.

[6] Das, B.M. (2001). Principles of Geotechnical Engineering 5th Ed. Thomson Learning Inc USA.

[7] Fellenius, W. (1936). Calculation of the stability of earth dams. Proc. Second Congress of Large Dams, Washington, v.4, pp.445-463

[8] Janbu, N. (1968). Slope stability computations. (Geoteknikk, NTH). Soil mechanics and foundation engineering, technical university of Norway

[9] Lowe, J., Karafiath, R. V. (1960) Stability of earth dam upon drawdown. Proceedings of the of the first pan american conference on soil mechanics and foundation engineering, Maxico City, pp 537–552

[10] Morgenstern, N.R., Price, V.E. (1965). The analysis of the stability of general slip surfaces. Geotechnique 15(1):79–93. doi:10.1680/geot.1965.15.1.79

[11] Moore, J.R., Sanders, J.W., Dietrich, W.E., Glaser, S.D. (2009). Influence of rock mass strength on the erosion rate of alpine cliffs. Earth Surf Proc Land 34(10):1339–1352. doi:10.1002/esp.1821



[12] Norme NF P 94-051, (1993). Soils, recognition and tests: determination of the Atterberg limits.

[13] Norme NF P 94-054, (1991). Soils, recognition and tests: determination of Absolute density

[14] Norme NF P 94-050, (1995). Soils, recognition and tests: determination of natural water contents

[15] Norme NF P 94-074, (1994). Soils, recognition and tests: determination of Triaxial shear

[16] Philipponnat and Hubert, (1997). Fondations et ouvrages en terre. Editions Eyrolles, 3ème édition.

[17] Romana M, Seron J B, Montalar E (2001). La clasificacion geomecanica SMR: aplicacion experiencias y validacion. In: CEDEX, UPM (eds) Proceedings of the V Simposio Nacional sobre taludes y laderas inestables. Centro de publicaciones, Secretaria General Tecnica. Ministerio de Fomento, CEDEX, Madrid, pp 393–404 (in Spanish)

[18] Romana, M., Seron, J.B., Montalar, E. (2003). SMR geomechanics classification: application, experience and validation. In: Merwe JN (ed) Proceedings of the 10th congress of the international society for rock mechanics, ISRM 2003—technology roadmap for rock mechanics. South African institute of mining and metallurgy, pp 1–4

[19] Romana, M., Seron J.B, Jorda, L., Velez, M.I. (2005). La clasificacion geomecanica SMR para taludes: Estado actual, aplicacion y experiencia internacional. In: Corominas J, Alonso E, Romana M, Hu¨rlimann M (eds) Proceedings of the VI Simposio Nacional sobre taludes y laderas inestables, Valencia, pp 239–250 (in Spanish)

[20] Selby, M.J. (1980). A rock mass strength classification for geomorphic purposes: with test rom Antarctica and New Zealand. Z fu¨r Geomorphol 24:31–51

[21] Spencer, E. (1967) A method of analysis of the stability of embankments, assuming parallel inter-slice forces. Geotechnique 17(1):11–26. doi:10.1680/geot.1967.17.1.11

stability assessment of the cut slopes in … finally stability assessment by bishop’s method to...

Documents