Conference PaperPDF Available

A REVIEW ON THE PULLOUT CAPACITY OF AN ANCHOR BLOCK EMBEDDED IN COHESIONLESS SOIL

Authors:

Abstract and Figures

In geotechnical engineering practices, vertical anchor blocks are considered as a robust structural measure to counter the exerted pullout forces from the retaining structure and to maintain the overall stability of it. Several theoretical models are available in the literature to estimate the pullout capacity of the vertical anchor in cohesionless soil. This paper aims to estimate the accuracy and reliability of those theoretical models by comparing the predicted pullout capacity with the experimental results available in the literature. For this purpose, a rigorous literature review is carried out to compile the experimental studies conducted on vertical anchor blocks. A comparative assessment among the theoretical prediction models to assess the pullout capacity is done based on six statistical parameters: Mean Absolute Percentage Error (MAPE), Root Mean Square Error (RMSE), McFadden’s pseudo R-square, Akaike Information Criterion (AIC), Bayesian Information Criterion (BIC), and Nash-Sutcliffe model efficiency coefficient. These comparisons reveal the relative strength and weakness of each theoretical model. Thus, it will help the engineers to take an informed decision before adopting any theoretical model for design purposes.
Content may be subject to copyright.
Proceedings of the 5th International Conference on Advances in Civil Engineering (ICACE 2020)
4-6 March 2021, CUET, Chattogram-4349, Bangladesh
Imam, Rahman and Pal (eds.)
A REVIEW ON THE PULLOUT CAPACITY OF AN ANCHOR BLOCK
EMBEDDED IN COHESIONLESS SOIL
M.E. Chowdhury1*, S. Sakib2
1Lecturer, Institute of Water and Flood Management (IWFM), Bangladesh University of Engineering and Technology (BUET),
Dhaka, Bangladesh, email: enayetchowdhury@iwfm.buet.ac.bd
2Graduate Research Assistant, The University of Texas at Arlington, Texas, USA, email: shadman.sakib@mavs.uta.edu
*Corresponding author
Abstract
In geotechnical engineering practices, vertical anchor blocks are considered as a robust structural measure to
counter the exerted pullout forces from the retaining structure and to maintain the overall stability of it. Several
theoretical models are available in the literature to estimate the pullout capacity of the vertical anchor in
cohesionless soil. This paper aims to estimate the accuracy and reliability of those theoretical models by
comparing the predicted pullout capacity with the experimental results available in the literature. For this purpose,
a rigorous literature review is carried out to compile the experimental studies conducted on vertical anchor blocks.
A comparative assessment among the theoretical prediction models to assess the pullout capacity is done based
on six statistical parameters: Mean Absolute Percentage Error (MAPE), Root Mean Square Error (RMSE),
McFadden’s pseudo R-square, Akaike Information Criterion (AIC), Bayesian Information Criterion (BIC), and
Nash-Sutcliffe model efficiency coefficient. These comparisons reveal the relative strength and weakness of each
theoretical model. Thus, it will help the engineers to take an informed decision before adopting any theoretical
model for design purposes.
Keywords
Vertical anchor blocks, Pullout capacity, Cohesionless soil
1. Introduction
Anchor installment is a widely-used soil reinforcement measure. Its design and construction are basically focused
on resisting outwardly directed imposed loads on the structure’s foundation. Several analyses have been done to
determine anchor plates’ capacity [1, 5, 10, 13, 14, 19, 24, 27, 28, 36, 37, 40, 42]. Compared to a relatively greater
number of researches on anchor plates, anchor blocks have drawn attention to a few. The behavior of anchor block
has been studied by a number of researchers [8, 18, 29, 34]. Empirical approximations have been a key feature of
current design practices. It is because of a large number of researches performed in the past is based on laboratory
or field experiments. Vertical anchor block has been an almost unexperimented field in terms of theoretical and
numerical analyses [11]. However, the effect of ground water table on the ultimate pullout loads of anchors has
been rarely studied. Summarizing the frequently used anchor design practices is the prime objective of this study.
Through this attempt, a rigorous discussion on the past studies on anchor blocks in addition to related potential
research approaches on it in future will be established. In this study, an apposite summary of pertinent researches
will be distinctly discussed based on experimental, theoretical and numerical studies. There is no endeavor to
propose an entire bibliography of all the relevant works of literature; it is rather intended to summarize the
researches with the closest relevance to the anchor block design. Currently, available pullout prediction models
will be discussed in a comparative approach with one another based on some statistical measures.
2. Previous experimental investigations
2.1 Investigations on anchor plates
Previous studies on anchor plates are illustrated in Table 1 and Table 2. Researchers’ predilection towards
experimental studies on anchor plates is quite noticeable in the post-2000 era. Within the last few years, the pattern
of anchor failure situated at various depths from the ground surface has been studied by Chowdhary and Dash
(2016). A noteworthy thing is where most of the researchers avoided the study of deep anchors, Akinmusuru
(1978), and Dickin and King (1997) focused their study on shallow, intermediate and deep anchors’ behavior.
Frictional angle effect on a wide range (29.5°-46.1°) was studied. Smith (1962) and Ovesen (1981) were found to
conduct field testing among the other researchers presented in Table 1. The maximum H/B (1-13) ratio was used
by Dickin and Leung (1983, 1985). Centrifuge testing was used in three studies: Ovesen (1981), Dickin and
Proceedings of the 5th International Conference on Advances in Civil Engineering (ICACE 2020)
4-6 March 2021, CUET, Chattogram-4349, Bangladesh
Imam, Rahman and Pal (eds.)
Leung (1983, 1985), Dickin and King (1997). Most of the studies were conducted on strip, rectangular or square
shape of the anchor, where Das (1975) and Akinmusuru (1978) conducted experiments on the circular shape of
anchors. It indicates that post-1980 researchers were not that much concerned about circular anchor plates.
2.2 Investigations on anchor blocks
Experimental studies on anchor blocks were limited in comparison to researches on anchor plates. Duncan and
Mokwa (2001), Naser (2006) and Khan et al. (2017) conducted their researches on anchor blocks (Table 3). The
field test was done only by Duncan and Mokwa (2001); the other two pieces of research were conducted in the
chamber. The maximum embedment ratio (H/B) is 3.2 among all three researches which indicate the anchor blocks
Table 2 Laboratory model tests and field tests on vertical anchor plate in cohesionless soil
Source
Type of testing
Anchor shape
Anchor
size (mm)
Friction
angle (°)
Heuckel (1959)
Chamber
Square
75-200
34
Smith (1962)
Field
Rectangular; L/B = 1.25, 5
915
38.5
Neely et al. (1973)
Chamber
Square; rectangular
50.8
38.5
Das (1975)
Chamber
Square; circular
3876
34
Das and Seely (1975)
Chamber
Square; rectangular; L/B = 1,3,5
51
34
Akinmusuru (1978)
Chamber
Strip; rectangular; square;
circular; L/B = 2, 10
50
24; 35
Ovesen (1981)
Centrifuge; field
Square
20
29.537.7
Rowe and Devis (1982)
Sand Chamber
Square; rectangular; L/B = 1
8.75
51
32
Dickin and Leung (1983,
1985)
Centrifuge
chamber
Square; rectangular; strip
25; 50
41a
Hoshiya and Mandal
(1984)
Sand chamber
Square; rectangular; L/B = 2, 4, 6
25.4
29.5
Murray and Geddes (1989)
Sand chamber
Square; rectangular; L/B = 110
50.8
43.6, dense
Dickin and King (1997)
Centrifuge
Rectangular; L/B = 7.8
25
37.346.1
Chowdhary and Dash
(2016)
Sand chamber
Square
100
3239
aMobilized plane strain friction angle, φ′mp
Table 1 Pertinent studies on anchors in cohesionless soil
Methods
Sources
Classification based
on anchor geometry
Anchor Plates
Heuckel (1959), Smith (1962), Neely et al. (1973), Das (1975), Das and
Seely (1975), Akinmusuru (1978), Ovesen (1981), Rowe and Devis
(1982), Dickin and Leung (1983, 1985), Hoshiya and Mandal (1984),
Murray and Geddes (1989), Dickin and King (1997), Chowdhary and
Dash (2016)
Anchor Blocks
Duncan and Mokwa (2001), Naser (2006), Khan et al. (2017)
Classification based on
Investigation Types
Theoretical
Investigations
Ovesen and Stromann (1972), NAVFAC DM 7.02 (U.S. Navy, 1986),
BS 8006 (1995), Ghaly (1997), Bowles (1997), Naser (2006),
Jadid et al. (2017)
Numerical
Investigations
Rowe and Davis (1982), Hanna et al. (1988),
Murray and Geddes (1989), Basudhar and Singh (1994), Merifield and
Sloan (2006), Bhattacharya and Kumar (2011), Hanna et al. (2011),
Bhattacharya and Kumar (2014), Bhattacharya and Roy (2016)
Proceedings of the 5th International Conference on Advances in Civil Engineering (ICACE 2020)
4-6 March 2021, CUET, Chattogram-4349, Bangladesh
Imam, Rahman and Pal (eds.)
were placed at shallow depth. Therefore, there is a large scope for the researchers to conduct experiments on
anchor behavior at intermediate and deep depths.
3. Previous theoretical investigations
In common, similar theoretical approaches are adopted for calculating the pullout capacity of vertical anchor plates
and anchor blocks [12]. Simple analytical approaches such as limit equilibrium and limit analysis were used in
previous theoretical studies of anchors in sand. On the contrary, limit analysis approach, developed by Drucker et
al. (1952), has two theorems: 1) Upper bound theorem and 2) Lower bound theorem. Determination of the ultimate
resistance of anchors in the sand through a quasi-empirical method was proposed by Ovesen and Stromann (1972).
According to NAVFAC DM 7.02 (1986), the anchor blocks should be placed outside the surface making an angle
equal to the angle of friction of backfill soil. BS 8006 (1995) emphasizes on using passive resistance coefficient
to calculate the pullout resistance of an anchor block. Passive earth pressure against short structures is relatively
higher than the predicted one by conventional Rankine and Coulomb theories which is not negligible [38]. Hansen
(1966) developed a method for correcting the results of conventional pressure theories for shape (or 3-D) effects.
For short anchors, the ultimate resistance should be multiplied by a coefficient (M) to account for 3-D effects.
However, the experimental studies by Khan et al. (2017) indicated that this coefficient is always less than 4. Ghaly
(1997) used the results of 104 laboratory tests, 15 centrifugal tests, and 9 field tests to propose an empirical
correlation. Bowles (1997) proposed a general equation to determine the horizontal pullout resistance of anchor.
Naser (2006) analyzed the pullout capacity of an anchor block using limit equilibrium approach. Jadid et al. (2017)
derived an equation where the ultimate pullout capacity for an anchor block with the dimension’s height, width,
thickness, and the depth of embedment below soil surface was calculated. They also developed charts for other
shapes of block.
4. Previous numerical investigations
In spite of the presence of numerous studies on experimental results, comparatively a reduced amount of numerical
analyses has been conducted in order to determine anchors’ pullout capacity in cohesionless soil (Merifield and
Sloan, 2006). A summary of some important previous numerical studies post-1980 on vertical anchors is provided
in Table 4. Observation of Table 4 reveals that most of the numerical studies on anchors focused on strip case and
no researches were found to report numerical studies on anchor blocks. Most recently, Bhattacharya and Kumar
(2011) investigated the effect of vertical spacing of anchor plates and anchor roughness on the pullout capacity of
vertical anchors using lower bound finite element analysis. Hanna and Rahman (2011) using limit analysis showed
that the stress-strain condition in a sand mass during and after the installation of an anchor plate, over-
consolidation ratio have a significant effect on the pullout capacity. Again, using numerical lower bound limit
analysis in combination with linear programming, Bhattacharya and Roy (2016) showed that pullout capacity
increases continuously with the decrease in normalized width. Thus, the concepts of anchor plate analyses may
provide significant insight into understanding the behavior of anchor block failure mechanism.
5. Discussions
Table 1 Laboratory model tests and field test on vertical anchor block in cohesionless soil
Source
Type of
Testing
Anchor Block
Shape
Anchor Block
size (mm)
Friction
angle (°)
H/B
Exclusive test condition
Duncan
and Mokwa
(2001)
Field
Rectangular;
L/B = 1.7
1100 x 1900 x 900
50
1
Blocks placed flush with
the ground surface using
two backfill materials
Naser
(2006)
Chamber
Square
150 x 150 x 150
43.5
2
Blocks’ pullout capacity
in saturated condition
Khan et al.
(2017)
Chamber
Square
150 x 150 x 75
37.2- 44.8
3.2
Blocks placed at different
distances from the
yielding retaining wall
Proceedings of the 5th International Conference on Advances in Civil Engineering (ICACE 2020)
4-6 March 2021, CUET, Chattogram-4349, Bangladesh
Imam, Rahman and Pal (eds.)
Only 7 test results (Table 5) were found in the literature to establish the most suitable method for an anchor block.
However, this comparison between the experimental results and theoretical predictions gives us an opportunity to
gain some useful information about the suitability of the theoretical methods in different conditions. For example,
when compared to the pullout capacity reported by Duncan and Mokwa (2001), the methods proposed by
NAVFAC DM 7.02 (1986), BS 8006 (1995), Ghaly (1997) gave an error of more than 50% (Table 5). Duncan
and Mokwa (2001) measured anchor block bearing against compacted gravel backfill near the ground surface.
Naser (2006) performed one laboratory test on 100% saturated sandy soil to observe the effect of degree of
saturation on pullout resistance of anchor. When compared to the pullout capacity observed by Naser (2006), the
methods proposed by Ovesen and Stromann (1972), NAVFAC DM 7.02 (1986) and BS 8006 (1995) gave an error
of more than 50%. The remaining 5 test results were conducted on poorly graded unsaturated sand. Each of the
method discussed here, except Jadid et al. (2017), gives an error of more than 50% for at least twice (Table 5).
Ovesen and Stromann (1972) considered the friction between wall and soil during upward movement of the
passive wedge. Bhattachyarya and Kumar (2014), Kumar and Sahoo (2012) showed numerically that
consideration of wall friction angle contributes favorably to pullout capacity. Again, anchor block moves together
with the passive wedge resulting in no shear displacement between the wall and passive wedge (Duncan and
Mokwa 2001). Thus, Ovesen and Stromann (1972) overestimated the test results in most of the cases. BS 8006
(1995) also significantly overestimated the test results in six out of seven cases. BS 8006 (1995) assumes that the
pullout resistance of anchor is four times the passive resistance of the soil. Whereas, experimental studies by Khan
et al. (2017) indicated this coefficient is always less than four. In other circumstances, Bowles (1997) method
underestimated each test results by a significant margin. Conventional earth pressure theories, assuming identical
cross section along the length of a structure was used in Bowles’s (1997) analysis. But such an assumption might
be suitable for heavy strip anchors. More importantly, the influence of different side conditions of the small
structure was omitted during the development of the theory, which is by far the single most important drawback.
As such, conventional theories provide a lower estimate of the pullout capacity. This is consistent with the findings
of Hanna et al. (2011) and Bilgin (2012). Ghaly’s (1997) empirical equation underestimated test results by more
than 50% (Table 5) for relatively denser soil on two occasions. The results of 104 laboratory tests, 15 centrifugal
tests, and 9 field tests were used to propose this empirical correlation. Unit weight and internal friction angle of
soil ranged from 14 to 16 kN/m3 and 34° to 38.5° respectively. It is expected that excess deviation from the range
of test parameters used to derive the empirical correlation might be the possible source of errors.
Table 4 Numerical studies on vertical anchors in cohesionless soil
This is probably the reason for the highest error corresponding to the test results of Duncan and Mokwa (2001),
where unit weight and internal friction angle of soil were 21.2 kN/m3 and 50° respectively. On the other hand,
Naser (2006) utilized the passive resistance coefficient proposed by Hansen (1966) to estimate the pullout capacity
of an anchor block. This coefficient is defined as the ratio of actual pullout resistance to the corresponding passive
resistance from Rankine theory acting in front of the anchor block.
Source
Analysis method
Anchor
shape
Anchor
roughness
Friction
angle (°)
H/B
Rowe and Davis
(1982)
Elastoplastic finite element
Strip
Smooth
045
18
Hanna et al. (1988)
Limit equilibrium
Strip;
inclined
Smooth
All
All
Murray and Geddes
(1989)
Limit analysis upper
bound
Strip;
inclined
Rough;
smooth
43.6
18
Basudhar and
Singh (1994)
Limit analysis lower
bound
Strip
Rough;
smooth
32; 35; 38
15
Merifield and Sloan
(2006)
Limit analysis upper and
lower bound
Strip
Rough;
smooth
2040
110
Bhattacharya and
Kumar (2011)
Limit analysis lower
bound
Strip
Rough;
smooth
2540
17
Hanna et al. (2011)
Limit analysis
Strip
Rough
3045
19
Bhattacharya and
Kumar (2014)
Limit analysis lower
bound
Strip;
inclined
Rough;
smooth
3040
310
Bhattacharya and
Roy (2016)
Limit analysis lower
bound
Strip
Rough;
smooth
3040
27
Proceedings of the 5th International Conference on Advances in Civil Engineering (ICACE 2020)
4-6 March 2021, CUET, Chattogram-4349, Bangladesh
Imam, Rahman and Pal (eds.)
Table 5 Comparison of theoretical predictions of pullout capacity with experimental results for vertical anchor block
Authors
Exp.
results
Ovesen and
Stromann (1972)
NAVFAC DM
7.02 (1986)
BS 8006 (1995)
Ghaly
(1997)
Bowles
(1997)
Naser
(2006)
Jadid et al.
(2017)
Pu
(kN)
Pu
(kN)
% error
Pu
(kN)
% error
Pu
(kN)
% error
Pu
(kN)
%
error
Pu
(kN)
% error
Pu
(kN)
% error
Pu
(kN)
% error
Duncan
and Mokwa
(2001)
410.0
427.0
4.1
768.0
87.3
735.0
79.2
190.0
-53.6
233.0
-43.2
297.0
-27.6
396.0
-3.4
1.3
1.9
46.1
1.8
38.5
1.9
46.2
1.0
-23.1
0.6
-53.8
1.3
0.0
1.2
-7.7
Naser
(2006)
2.3
2.0
-13.0
2.0
-13.0
2.2
-4.3
1.1
-52.2
0.7
-69.6
1.5
-34.8
1.4
-39.1
0.71
1.5
114.3
1.1
57.1
1.2
71.4
0.6
-14.3
0.4
-42.9
0.8
14.3
0.7
0.0
Khan et al.
(2017)
1.9
2.2
15.8
1.5
-21.1
2.2
15.8
2.1
10.5
0.6
-68.4
1.8
-5.3
1.1
-42.1
2.1
3.1
47.6
3.0
42.9
3.1
47.6
1.8
-14.3
0.9
-57.1
3.6
71.4
1.7
-10.5
2.3
3.5
52.2
3.8
65.2
3.6
56.5
1.9
-17.4
1.0
-56.5
4.4
91.3
2.0
-13.0
1Pullout resistance at 100% saturated condition
Table 6 Cumulative frequency distribution of the available pullout capacity prediction models
Absolute
% error
Ovesen and
Stromann (1972)
NAVFAC DM 7.02
(1986)
BS 8006
(1995)
Ghaly
(1997)
Bowles
(1997)
Naser
(2006)
Jadid et al. (2017)
Freq-
ency
Cum.
Freq-
Ency
Freq-
ency
Cum.
Freq-
ency
Freq-
Ency
Cum.
Freq-
ency
Freq-
Ency
Cum.
Freq-
ency
Freq-
ency
Cum.
Freq-
ency
Freq-
ency
Cum.
Freq-
ency
Freq-
ency
Cum.
Freq-
ency
0-10
1
1
0
0
1
1
0
0
0
0
2
2
3
3
10-20
2
3
1
1
1
2
4
4
0
0
1
3
2
5
20-30
0
3
1
2
0
2
1
5
0
0
1
4
0
5
30-40
0
3
1
3
0
2
0
5
0
0
1
5
1
6
40-50
2
5
1
4
2
4
0
5
2
2
0
5
1
7
>50
2
7
3
7
3
7
2
7
5
7
2
7
0
7
Proceedings of the 5th International Conference on Advances in Civil Engineering (ICACE 2020)
4-6 March 2021, CUET, Chattogram-4349, Bangladesh
Imam, Rahman and Pal (eds.)
Table 7 Goodness of fits for different methods
From experimental investigation, Khan et al. (2017) observed significant discrepancy between experimental
results and predictions of passive resistance coefficient using Hansen (1966) model. From a statistical point of
view, Jadid et al. (2017) give an absolute error in the range, 0 to 15% in 5 out of 7 cases. For the remaining cases,
it underestimates the actual results by 30% to 45%. Table 7 shows that Jadid et al. (2017) gives the best result in
all six goodness of fits. BS 8006 (1995) method is comparatively better than other methods except Jadid et al.
(2017), as it produces the best result after Jadid et al. (2017) according to Root Mean Square Error (RMSE),
McFadden’s Pseudo R-square, Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC).
6. Conclusions
After comparing the data obtained from the experimental investigations and from the different theoretical methods,
the following principal conclusions are made.
Jadid et al. (2017) method seemed to predict the pullout capcity of an anchor block more accurately than
any other methods according to different six statistical goodness of fits since their method was devised
exclusively for an anchor block. In addition, the water table correction is also properly accounted for in
this method. BS 8006 (1995) comes second to Jadid et al. (2017) in terms of predicting the pullout capacity
of anchor block according to four different statistical parameters.
The accuracy of the Ghaly’s (1997) empirical method was found to be satisfactory with the experimental
studies for sandy soil. Due to its simplicity and computational efficiency, it can be used for a rough
estimation of the pullout capacity of an anchor block.
Bowles’s (1997) method considered plain strain condition to develop his theory which is the case for strip
anchor. Thus, it is probably not suitable for an anchor block where the different end condions due to 3-D
effect needs to be considered.
Ovesen and Stromann’s (1972) method can be used when the anchor is heavy (e.g., strip anchor) which
causes the development of friction between wall and soil.
Goodness
of
Fits
Ovesen and
Stromann
(1972)
NAVFAC
DM
7.02
(1986)
BS 8006
(1995)
Ghaly
(1997)
Bowels
(1997)
Naser
(2006)
Jadid et al.
(2017)
Mean
Absolute
Percentage
Error
(MAPE)
41.9
46.4
45.9
26.5
55.9
35
16.5*
Root Mean
Square
Error
(RMSE)
0.523
0.461
0.369
0.949
0.386
1.612
0.361*
McFadden's
Pseudo
R-square
0.99999042
0.9999926
0.9999952
0.9999685
0.9999948
0.999909
0.9999954*
Akaike
Information
Criterion
(AIC)
14.4
12.7
9.6
22.8
10.2
30.2
9.2*
Bayesian
Information
Criterion
(BIC)
14.3
12.5
9.4
22.6
10.02
30.04
9.1*
Nash-
Sutcliffe
Model
Efficiency
Co-efficient
0.998
0.103
0.261
0.661
0.781
0.911
0.999*
Proceedings of the 5th International Conference on Advances in Civil Engineering (ICACE 2020)
4-6 March 2021, CUET, Chattogram-4349, Bangladesh
Imam, Rahman and Pal (eds.)
Rigorous experimental, theoretical, and numerical studies should be conducted focusing anchor blocks, as the
present state of the art does not warrant the use of anchor plate theories to analyse anchor block behaviour.
Sufficient field observations are required to develop confidence among the users about the suitability of different
methods mentioned in this paper. The authors hope that this paper will be useful to all those dealing with civil
engineering projects and research works on the anchored retaining wall. This article will also be helpful to those
who are involved in the development of standards for the determination of horizontal pullout capacity of an anchor
block embedded in cohesionless soil.
7. Acknowledgement
We thank Mr Azmayeen Rafat Shahriar, graduate student in the North Carolina State University, Raleigh, United
States, Mr Rowshon Jadid, graduate teaching and research assistant in the North Carolina State University,
Raleigh, United States, and Mr Tanvir Imtiaz, research assistant in the University of Texas at Arlington, United
States, for their valuable inputs throughout this research work.
8. References
[1] Akinmusuru JO (1978) Horizontally loaded vertical plate anchors in sand. J Geotech Eng Division (ASCE)
104(2):283-286
[2] Basudhar PK, Singh DN (1994) A generalized procedure for predicting optimal lower bound break-out factors
of strip anchors. Géotechnique 44(2):307-318
[3] Bhattacharya P, Kumar J (2011) Horizontal pullout capacity of a group of two vertical strip anchors plates
embedded in sand. Geotech Geol Eng 30(2), 513-521
[4] Bhattacharya P and Kumar J (2014) Pullout capacity of inclined plate anchors embedded in sand. Can Geotech
J 51(11):1365-1370
[5] Bhattacharya P, Roy A (2016a) Variation of horizontal pullout capacity with width of vertical anchor plate.
Int J Geomech 16(5):06016002
[6] Bhattacharya P, Roy A (2016b) Improvement in uplift capacity of horizontal circular anchor plate in undrained
clay by granular column. Geomech Eng Int J, 10(5):617-633
[7] Bilgin O (2012) Lateral earth pressure coefficients for anchored sheet pile walls. Int J Geomech 12(5):584-
595.
[8] Bowles JE (1997) Foundation Analysis and Design (5th ed.). The McGraw-Hill Companies, Singapore
[9] BS 8006 (1995) Strengthened/Reinforced Soils and Other Fills (Section 6.6), British Standard, London
[10] Choudhary AK, Dash SK (2016) Load-carrying mechanism of vertical plate anchors in sand. Int J
Geomech 04016116
[11] Das BM (1990) Earth Anchors, Elsevier, Amsterdam, Netherlands
[12] Das BM (2007) Principles of Foundation Engineering (6th ed.). Thomson Brooks/Cole, Ontario, Canada
[13] Das BM, Seeley GR (1975) Load-displacement relationships for vertical anchor plates. J Geotech Eng
Division (ASCE). 101(GT7):711-715
[14] Demir A, Ok B (2015) Uplift response of multi-plate helical anchors in cohesive soil. Geomech Eng Int
J 8(4):615-630
[15] Dickin EA, King JW (1997) Numerical modelling of the load-displacement behavior of anchor walls.
Computers and Structures 63(4):849-858
[16] Dickin EA, Leung CF (1983) Centrifuge model tests on vertical anchor plates. J Geotech Eng (ASCE),
109(12):1503-1525
[17] Dickin EA, Leung CF (1985) Evaluation of design methods for vertical anchor plates. J Geotech Eng
(ASCE) 111(4):500-520
[18] Duncan M, Mokwa R (2001) Passive earth pressures: theories and test. J Geotech Geoenviron. Eng.
(ASCE) 127(4):248-257
[19] Ghaly AM (1997) Load-displacement prediction for horizontally loaded vertical plates. J Geotech
Geoenviron Eng (ASCE) 123(1):74-76
[20] Hanna AM, Das BM, Foriero A (1988) Behavior of shallow inclined plate anchors in sand. Geotech
Special Publ (ASCE) 16:54-72
[21] Hanna A, Rahman F, Ayadat T. (2011) Passive earth pressure on embedded vertical plate anchors in
sand. Acta Geotechnica 6:21-29
[22] Hansen JB (1966) Resistance of rectangular anchor slab. Danish Geotech Inst 21:12-13
[23] Hoshiya M, Mandal JN (1984) Some studies of anchor plates in sand. Soils Found 24(1):9-16
Proceedings of the 5th International Conference on Advances in Civil Engineering (ICACE 2020)
4-6 March 2021, CUET, Chattogram-4349, Bangladesh
Imam, Rahman and Pal (eds.)
[24] Hueckel S (1957) Model tests on anchoring capacity of vertical and inclined plates. Proc 4th Int Conf
Soil Mech Found Eng London 2:203-206
[25] Jadid R, Abedin Z, Shahriar AR, Arif ZU (2017) Analytical model for pullout capacity of a vertical
concrete anchor block embedded at shallow depth in cohesionless soil. Int J Geomech 18(7):1-8
[26] Jones C (1996) Earth reinforcement and soil structures. Thomas Telford Services Ltd London UK
[27] Kame GS, Dewaikar DM, Choudhury D (2012) Pullout capacity of a vertical plate anchor embedded in
cohesionless soil. Geomech Eng Int J 4(2),105-120
[28] Keskin MS (2015) Model studies of uplift capacity behavior of square plate anchors in geogrid-
reinforced sand. Geomech Eng Int J 8(4):595-613
[29] Khan AJ, Mostofa G, Jadid R (2017) Pullout resistance of concrete anchor block embedded in
cohesionless soil. Geomech Eng An Int J 12(4):675-688
[30] Kumar J, Sahoo JP (2012) Upper bound solution for pullout capacity of vertical anchors in sand using
finite elements and limit analysis. Int J Geomech 12(3):333-337
[31] Merifield RS, Sloan SW (2006) The ultimate pullout capacity of anchors in frictional soils. Can Geotech
J 43:852-868
[32] Murray EJ, Geddes JD (1987) Uplift of anchor plates in sand. J Geotech Eng (ASCE) 113(3):202-215
[33] Murray EJ, Geddes JD (1989) Resistance of passive inclined anchors in cohesionless medium.
Géotechnique 39(3):417-431
[34] Naser AS (2006) Pullout capacity of block anchor in unsaturated sand. Proc. 4th Int Conf Unsat Soils,
Arizona April 403-414
[35] NAVFAC DM 7.02 (1986) Foundations and earth structures, Naval Facilities Engineering Command
Alexandria
[36] Neely WJ, Stuart JG, Graham J (1973) Failure loads of vertical anchor plates in sand. J Geotech Eng
Division (ASCE) 99(9):669-685
[37] Niroumand H, Kassim KA (2013) A review on uplift response of symmetrical anchor plates embedded
in reinforced sand. Geomech Eng Int J 5(3):187-194
[38] Ovesen NK (1964) Anchor Slabs, Calculation Methods, and Model Tests. Bull. No. 16, Danish
Geotechnical Institute Copenhegen 5-39
[39] Ovesen NK (1981) Centrifuge tests of the uplift capacity of anchors. Proc 10th Int Conf Soil Mech Found
Eng Stockholm Rotterdam Netherlands 717-722
[40] Ovesen NK, Stromann H (1972) Design methods of vertical anchor slabs in sand. Proc Specialty Conf
Perform Earth Earth-Supported Structures (ASCE) Indiana 2.1:1481-1500
[41] Rowe RK, Davis H (1982) The behavior of anchor plates in sand. Géotechnique 32(1):25-41
[42] Singh V, Maitra S, Chatterjee S (2016) Generalized design approach for strip anchors in clay. Int J
Geomech 04016148
[43] Smith JE (1962) Deadman anchorages in sand. Washington DC US Naval Civil Engineering Laboratory
ResearchGate has not been able to resolve any citations for this publication.
Article
Full-text available
The anchor block is a specially designed concrete member intended to withstand pullout or thrust forces from backfill material of an internally stabilized anchored earth retaining wall by passive resistance of soil in front of the block. This study presents small-scale laboratory experimental works to investigate the pullout capacity of a concrete anchor block embedded in air dry sand and located at different distances from yielding boundary wall. The experimental setup consists of a large tank made of fiberglass sheets and steel framing system. A series of tests was carried out in the tank to investigate the load-displacement behavior of anchor block. Experimental results are then compared with the theoretical approaches suggested by different researchers and codes. The appropriate placement of an anchor block and the passive resistance coefficient, that is multiplied by the passive resistance in front of the anchor block to obtain the pullout capacity of the anchor, were also studied.
Article
Full-text available
A series of tests is described on model anchor plates in sand. The results are presented in the form of dimensionless force coefficients and shape factors rrelating failure loads to the geometry of the anchor and its depth of embedment. The method of stress characteristics is used to produce comparable theoretical values which agree well with experimental results at both model and field scales. The measured shape factors are independent of the size of the plate, and this contrasts with the force coefficients which decrease with increasing anchor size.
Article
The passive resistance of inclined anchor plates in sand is examined. Laboratory experimental results are presented for the ultimate passive resistance, and the corresponding displacements, of rectangular anchor plates pulled at angles of inclination between the vertical and the horizontal through very dense sand. The results of ultimate passive resistance are compared with theoretical solutions based on the upper and lower bound limit theorems of soil plasticity. A general lower bound solution for a strip anchor pulled at various angles of loading cannot be readily formulated, and only a poor lower bound solution for the case of horizontal loading is determined. However, it is shown that provided interface friction is taken into account, upper bound solutions for a strip anchor compare favourably with the experimental evidence. Good agreement is shown between the upper bound solutions and the equivalent free surface stress characteristic solution, and experimental data, of Neely et al. (1973) for the horizontal translation of anchor plates in medium dense sand. Comparison is also made between the experimental results of this Paper and the finite element approach of Rowe & Davis (1982) for anchors pulled horizontally through an assumed elastic-plastic soil. L'article examine la résistance passive des plaques d'ancrage inclinées. Les résultats de quelques expériences effectuées en laboratoire sont présentés concernant la résistance passive limite et les déplacements correspondants de plaques d'ancrage rectangulaires arrachées selon des directions comprises entre la verticale et l'horizontale à travers du sable de grande densité. Les résultats pour la résistance passive limite sont comparés avec des solutions théoretiques basées sur les valeurs supérieures et inférieures possibles des théories de la plasticité du sol. Il est difficile de formuler une solution générale pour les valeurs inférieures pour une plaque d'ancrage extraite à des angles différents tandis qu'on ne détermine qu'une solution peu satisfaisante pour les valeurs inférieures dans le cas du chargement horizontal. Nénamoins, à condition qu'on tienne compte du frottement d'interface, les solutions dans les valeurs supérieures s'accordent très bien avec les résultats expérimenteaux. On démontre un accod satisfaisant entre les solutions limites des valeurs supérieures et la solution equivalent basée sur les caractéristiques de contrainte superficielle libre et les données expérimentales de Neely et autres (1973) pour la translation horizontale des plaques d'ancrage dans du sable de densité moyenne. On compare aussi les résultats décrits dans cet article avec la méthode aux éléments finis de Rowe et Davis (1982) pour des ancrages horizontalement à travers un sol élastoplastique.
Article
This paper focuses on the theoretical investigations into the behavior of a concrete anchor block embedded in cohesionless soil. The research was carried out for the purpose of devising an analytical method for attaining a reliable and accurate estimate of the pullout capacity of an anchor block embedded at shallow depth. To this end, it was assumed that a passive wedge of soil developed in front of the anchor block, due to the force exerted from the retaining structure via the attachment to a rebar. The limit equilibrium of the wedge was satisfied, and relevant assumptions were made to idealize the geometry of a failure mechanism. For simplicity in hand calculations, design charts were developed, utilizing the ratio of the breakout factor to the embedment depth to obtain the pullout capacity of an anchor block. The proposed theoretical estimation was compared with existing theoretical and experimental investigations for accuracy and reliability, and the comparison clearly showed the superiority of the proposed method in both the areas. Moreover, the effects of the placement of anchor blocks in relation to retaining structures were studied.
Article
An experimental study on the load-carrying mechanism of vertical plate anchors is presented and discussed. It was found that, with a shallow anchor, the rupture surface reached the ground surface, leading to a general shear failure, whereas with deeper embedment, the rupture surface was localized around the anchor. Anchors placed close to the ground surface failed in linear rupture but, when embedded within the failure mechanism, were very close to the polar curve of a logarithmic spiral, which, however, tends to be nearly circular for deeper depths of embedment. The size of rupture surface increases with an increase in density of fill soil that mobilizes higher resistance, leading to enhanced anchor capacity. The critical embedment depth beyond which the anchor breakout factor does not change much is found to be approximately 7 times the anchor height for dense soil, whereas it is approximately 5 times the anchor height for loose soil. The anchor when placed below the critical depth, settlement, and heave on the fill surface tend to be marginal.
Article
The estimation of the undrained pullout capacity of plate anchors is vital for the design of offshore floating facilities and has been an active topic of research for several years. Most of the previous studies have proposed empirical relationships to predict the undrained pullout capacities of inclined anchors. Generally, the buoyancy effect is added to the shearing resistance to obtain the total capacity, which is less than or equal to the maximum capacity. In this paper, an alternative mechanism-based simple design methodology is proposed to estimate the undrained pullout capacity of inclined anchors. A series of finite-element analyses are performed for a range of anchor inclinations in soils with uniform and heterogeneous shear strength. The effects of anchor embedment, soil unit weight, and anchor–soil interface tensile capacity are studied in a systematic manner. A relationship has been developed to estimate the depth at which the anchor undergoes a transition in the failure mechanism from shallow to deep failure mode. Robustness of the proposed methodology is also examined for a generalized shear strength profile of the soil. The proposed model estimates pullout capacity with the maximum error being less than 5% for any soil or anchor property.
Article
A numerical study has been conducted to examine the improvement achieved in the ultimate pullout capacity of horizontal circular anchor plates embedded in undrained clay, by constructing granular columns of varying diameter over the anchor plates. The analysis has been carried out by using lower bound theorem of limit analysis and finite elements in combination with linear programming. The improvement in uplifting capacity of anchor plate is expressed in terms of an efficiency factor (ξ). The efficiency factor (ξ) has been defined as the ratio of ultimate vertical pullout capacity of anchor plate having diameter D embedded in soft clay reinforced by granular column to the vertical pullout capacity of the anchor plate with same diameter D embedded in soft clay only. The variation of efficiency factor (ξ) for different embedment ratios and different diameter of granular column has been studied considering a wide range of softness of clay and different value of soil internal friction angle (Φ) of the granular material. It is observed that ξ increases with an increase in diameter of the granular column (Dt) and increase in friction angle of granular material. Also, the effectiveness of the usage of granular column increases with decrease in cohesion of the clay.
Article
The variation of pullout capacity of vertical strip anchor plates with width was studied while considering the effect of mean normal stress on the peak friction angle in a granular soil domain. This analysis was performed by using lower-bound finite-element limit analysis in conjunction with linear programing. The study was conducted for a wide range of anchor widths (B) and embedment depths (H) for both loose and dense sands. It was determined that the pullout capacity factor (Fγ = Pu/γBH) increases with decreasing values of normalized anchor width (γB/σA), where Pu is the ultimate pullout load; γ is the unit weight of soil mass; and σA is the atmospheric pressure. The rate of change for increments of Fγ with γB/σA was found to be more pronounced when the anchor is embedded in loose sand and at greater embedment depths.
Article
The use of model testing for solving design problems in soil mechanics is discussed with special reference to the scaling law relationship. As an example the uplift capacity of anchor slabs in sand is considered. The potential of the centrifugal testing technique is demonstrated. On the basis of centrifugal model tests, formulas are derived for the uplift capacity of circular and square anchor slabs in sand pulled in a vertical and in a slanting direction. Refs.