1. Thesis Advisor : Dr.P.Ghosh
By:
Piyush Sarangi
12103045
Geotechnical Engg

2.  Soil nailing is the most popular method of in situ ground improvement
technique which is used to stabilize the vertical cuts and slopes by offering
passive resistance.
 It offer resistance to shearing through tension, bending and shear.
 Divide the slopes into two zones i.e. active and resistive zone
 As the slope deforms due to external load it exerts a drag force(Pull out)
on nail in active zone which is balanced by the frictional resistance
mobilized between nail and surrounding soil in the resistive zone.
 The interaction length behind the slip surface in resistive zone is known as
bond length.
Active and resistive zone

3.  Stability analysis of soil nailed slope has been studied by several
researchers among them Stocker et al(1979) was the first to study
about the stability of soil nailed slope which is know as the famous
GERMAN METHOD.
 But the main concern was how the soil nailed slope behave under
seismic conditions, several studies were performed by several
researchers on the stability analysis of reinforced soil subjected to
seismic loading and several interpretations were made . Sakaguchi
M(1996) was the first to study about the reinforced soil.
 As seismic stability analysis of the of the nailed slopes was a very
rigorous and costly issue and could not performed by all . To
overcome these drawbacks pseudo static and dynamic methods were
come into picture.

4. Name Contribution
Okabe(1926) Reported earth quake lateral earth pressure behind
retaining wall using limit Equilibrium and pseudo
static method considering failure surface to be linear
and passing through toe
Monobe and Matsuo(1929) Studied seismic lateral earth pressure behind the
retaining wall in active and passive conditions using
pseudo static method similar to above method but
wall and ground inclinations were also considered
Steedman and zeng(1990) First to propose pseudo dynamic method behind the
vertical cantilever retaining wall considering finite
shear wave velocity in the backfill .The amplification
of acceleration and non uniform shear modulus was
considered.
Choudhury and Nimbalkar(2005) First to modify the pseudo dynamic method of
steedman and zeng by considering horizontal as well
as vertical accelerations which were dependent on
the shear and p-wave velocity with in the backfill

5. SOIL NAILING
Stocker et al.(1979) First to study about the stability analysis of nailed slope
by large scale field tests and model tests measured the
deformation within the reinforced soil and observed
two failure mechanisms based on position of load on
the slope.
Sakaguchi M(1996) Studied different design methods like limit
equilibrium, limit analysis and FEM method as well as
proposed optimum design of nailed slope by sequential
unconstrained minimization technique
Patra and Basudhar(2005) Here computer based optimum design of soil nailed
slope was reported .A limit equilibrium formulation
satisfying overall and internal stability and considering
tensile resistance of reinforcement was used for the
computation of stability of nailed slopes
Meenal et.al(2005) Here seismic stability analysis of the soil nailed
embankment was performed by pseudo static analysis.
The failure surface assumed to be log spiral and
internal stability analysis was done by means of
moment equilibrium method
Choudhury et.al(2009) Used pseudo dynamic method for determination of
internal stability of RE wall by horizontal slices
method. Results were presented in graphical and
tabular form to show the required tensile force and
length of geosynthetic to maintain stability. The effects
of variation of parameter such as friction angle of soil,
horizontal and vertical acceleration on stability of RE
wall was also investigated

6. Reddy et.al(2009) Used the pseudo dynamic method to determine the
seismic stability of the reinforced wall subjected to
pullout and oblique force by sliding of soil masses.
The seismic stability analysis was carried out
considering the kinematics of oblique pull. The
parametric studies quantify the effects of different
parameters on F.O.S considering increase in tension
due to oblique pull and pseudo dynamic forces.
Sengupta and Giri (2011) Here stability analyses of the nailed soil slopes were
presented by kinematic limit approach. Here
earthquake forces were incorporated by means of
pseudo static method. Two types of failure surfaces i.e.
planar and circular were considered. The F.O.S and
nailed forces were found out to be good agreement
with publishes results

7.  Max no. of studies till now performed are
based on reinforced earth structures and very
Less no. of studies based on seismic
performance of the soil nailed slopes.
 The available studies of soil nailed slopes have
been performed based on Pseudo static method
which is very less realistic
 Studies are yet to performed on seismic
stability analysis of soil nailed slopes based on
pseudo-dynamic method

8. PSEUDO-STATIC PSEUDO –DYNAMIC
 Proposed by Monobe-Okabe(1926)
 Horizontal and vertical
accelerations considered to be time
independent
 Here the shear wave velocity is
assumed to be infinity as soil
wedge is considered to be rigid.
 Does not consider the shear
modulus variation
 Magnitude and phase of
acceleration are considered
uniform throughout the backfill
 Less realistic
 Proposed by Steedman & zeng(1990)
 Time dependent
 Finite shear and P-wave velocity
through out the backfilled
 Non uniform shear modulus
variation through out the backfill
 Magnitude same as pseudo static
analysis but phase changes with
respect to time.
 More realistic

9.  Pseudo-dynamic analysis of soil nailed slope
Soil Nailed Slope Pseudo dynamic method

10.  Pseudo-dynamic formulation
 Max force determination in the nails by
incorporating the skin friction between nail and
surrounding soil or bond resistance of soil nail.
 Stability check by performing slope stability
analysis under static and dynamic loads.
 Variation of coefficient of horizontal and
vertical acceleration cofficient with respect to
different parameters

11.  Okabe, S. (1926) General Theory of Earth Pressure, Journal of the Japanese Society of Civil Engineers,
Tokyo, Japan,12(1).
 Mononobe, N. and Matsuo, H. (1929) On the determination of earth pressure during earthquakes,
Proceedings, World Engineering Conference, Vol. 9, 176 p.
 Steedman, R.S. and Zeng, X. (1990) The influence of phase on the calculation of pseudo-static earth
pressure on a retaining wall, Geotechnique, 40(1), 103–112
 Kramer, S.L. (1996)Geotechnical Earthquake Engineering, New Jersey, Prentice Hall
 Choudhury D, Nimbalkar S. Seismic passive resistance by pseudo dynamic method. Geotechnique
2005; 55 (9):699–702
 Choudhury, D., Nimbalkar, S. S. & Mandal, J. N. (2007). External stability of reinforced soil-walls
under seismic condition.Geosynthetics International, 14, No. 4, 211–218.
 Nimbalkar, S. S., Choudhury, D. & Mandal, J. N. (2006a). Seismic stability of reinforced soil wall by
pseudo-dynamic method. Geosynthetics International, 13, No. 3, 111–119
 Shahgholi, M., Fakher, A. & Jones, C. J. F. P. (2001).Horizontal slice method of analysis.Ge´otechnique,
51, No. 10, 881–885
 Ahmad, S. M. & Choudhury, D. (2008).Pseudo-dynamic approach of seismic design for waterfront
reinforced soil wall. Geotextiles and Geomembranes, 26, No. 4, 291–301
 Saran S, Mittal S, Gosavi M (2005) Pseudo static analysis of nailed vertical excavations in sands. Indian
Geotech J 35(4):401–417
 Patra CR, Basudhar PK (2001) Nailed soil structure: an overview. Indian Geotech Journal 31(4):322–362
 Giri D and Sengupta A (2009) Dynamic behavior of small scale nailed soil slopes. International Journal
of Geotechnical and Geological Engineering 27(6): 687–698
 Sengupta A and Giri D (2011) Dynamic analysis of soil nailed slope. Ground Improvement 164(GI4)
225-234