This study comprehensively analyzes seismic active earth pressure estimation for hunched retaining walls. The analysis utilizes the horizontal slices method within the modified pseudo-dynamic ...framework and incorporates depth-dependent dynamic parameters for the backfill soil. The friction angle of the backfill soil varied between 30° and 45°, while the hunch angle of the retaining wall increased from 0° to 20°. The findings of this study demonstrate that the use of hunched retaining walls results in a significant reduction in active earth pressure. In both static and dynamic cases, reductions of up to 23% and 18%, respectively, compared to vertical walls, were observed. Notably, this reduction is more pronounced for smooth walls under static conditions than for rough walls under dynamic conditions. The estimated active earth pressures for both vertical and hunched walls in static and dynamic scenarios closely align with those reported in the literature. Additionally, an empirical equation based on an artificial neural network model, utilizing the numerical analysis result, is proposed to establish a relationship between the investigated design parameters and the active earth pressure coefficient. The proposed equation demonstrated a high coefficient of determination (R
2
) value of 99.78% when compared to the numerical results. This study’s outcomes provide valuable insights and a tool for practicing engineers in the field.
AbstractThe lower- and upper-bound finite-element limit analysis in conjunction with second-order conic programming (SOCP) was used to estimate the ultimate bearing capacity of strip and circular ...footings with an inclusion of a layer of dense sand over existing loose sand strata. The analysis followed the Mohr-Coulomb yield criterion and an associated flow rule. The results are expressed in terms of an efficiency factor that increases quite significantly with increases in the (1) thickness and (2) friction angle of the upper densified layer. While keeping the same thickness of the upper dense sand layer, the circular footing exhibits greater efficiency-factor values as compared to strip footing. The numerical results compare well with data available from the literature.
In the present study, the uplift capacity of the under-reamed piles (also referred to as belled piles) in the sand was determined by following a finite element analysis. In this regard, the soil was ...assumed to obey Mohr-Coulomb's failure criteria, together with a non-associated flow rule. The pile geometry, soil, and pile properties were selected by following relevant literature. The friction angle (ϕ) of sand varied from 25°-45°, whereas the embedment ratio (L/D) of the pile was kept between 7.0-17.5. The computed uplift capacity was expressed in a non-dimensional manner. After comparison of uplift capacity with literature, an analytical equation to predict the uplift capacity of under-reamed\belled piles was developed using the generated failure patterns from numerical analysis. The proposed equation was validated using 300 datasets from literature which includes field and laboratory test both. The uplift capacity estimated with the developed equation correlates well with literature as the R
2
value in all the cases was greater than 0.99.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
A numerical study has been conducted to compute the ultimate bearing capacity of the embedded strip and circular footing placed on loose sand, which is densified in the upper region as well as ...reinforced with a geogrid sheet at the interface of loose and dense sand layers. The analysis was carried out using the lower and upper bound finite elements limit analysis in conjunction with the second-order conic programming. The friction angle
ϕ
1
of the upper dense sand layer was varied from 40° to 46°; on the other hand, the friction angle
ϕ
2
of the lower strata was varied from 30° to 36°. The bearing capacity (
q
u
)
for different combinations of
D
f
/B, the friction angles of the two layers, with and without the provision of the geogrid sheet, was expressed in terms of a non-dimensional efficiency factor (the ratio of
q
u
for footing on layered sand to that for a footing placed entirely on bottom loose sand strata). The efficiency factor increased significantly for a given friction angle of the loose sand, increasing the friction angle of top dense sand. The provision of the geogrid sheet was found to affect the efficiency factor of the unreinforced foundation marginally. However, a considerable reduction in the dense sand layer’s thickness compared to the unreinforced case was observed. The results obtained from the analysis were compared with the different solutions reported in the literature for footing on the reinforced and unreinforced cases.
The vertical uplift resistance of circular plate anchors, embedded horizontally in a clayey stratum whose cohesion increases linearly with depth, has been obtained under undrained (
ϕ
=
0) condition. ...The axi-symmetric static limit analysis formulation in combination with finite elements proposed recently by the authors has been employed. The variation of the uplift factor (
F
c
) with changes in the embedment ratio (
H/
B) has been computed for several rates of increases of soil cohesion with depth. It is noted that in all the cases, the magnitude of
F
c
increases continuously with depth up to a certain value of
H
cr/
B beyond which the uplift factor becomes essentially constant. The proposed static limit analysis formulation is seen to provide acceptable results even for the two other simple chosen axi-symmetric problems.
By incorporating the variation of peak soil friction angle (
φϕ
) with mean principal stress ( σ
m
), the effect of anchor width (B) on vertical uplift resistance of a strip anchor plate has been ...examined. The anchor was embedded horizontally in a granular medium. The analysis was performed using lower bound finite element limit analysis and linear programming. An iterative procedure, proposed recently by the authors, was implemented to incorporate the variation of
φϕ
with σ
m
. It is noted that for a given embedment ratio, with a decrease in anchor width (B), (i) the uplift factor (F
γ
) increases continuously and (ii) the average ultimate uplift pressure (q
u
) decreases quite significantly. The scale effect becomes more pronounced at greater embedment ratios.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The present paper tries to explore the load-settlement behavior of an under-reamed pile subjected to either compressive or pull-out loading and installed in clay whose cohesion increases linearly ...with depth. In this regard, the finite element analysis was performed using OptumG2 software wherein the soil was assumed to obey Mohr–Coulomb’s failure criterion under the undrained condition. For the selected pile geometry, the analysis was performed for the different values of linearly increasing cohesion and for the various shaft adhesion. The comparison of results for single and double under-reamed pile with a uniform diameter pile suggests that the provision of a bulb or under-reamed section to the pile helps in the increase in safe load and decrease in the settlement up to a certain value of the slope of linearly increasing cohesion. Additionally, the effect of no tension condition at the base of a pile on the safe and ultimate capacity was examined. The present results were found to compare well with that available literature.
By using the axisymmetric finite elements static limit analysis formulation, proposed recently by the authors, the stability numbers (
γH/
c
o
) for an unsupported vertical circular excavation in ...clays, whose cohesion increases with depth, have been determined under undrained condition;
γ
=
unit weight,
H
=
height of the excavation and
c
o
=
cohesion along ground surface. The results are obtained for various values of
H/
b and m; where
b
=
the radius of the excavation and
m
=
a non-dimensional parameter which accounts for the rate of the increase of cohesion with depth. The values of the stability numbers increase continuously both with increases in
H/
b and
m. The results obtained in this study compare well with those available in literature.
