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Register a new userAnalysis the Effect of Variation in Vertical Core Thickness on Stability of Earth Dams (Case Study: Dwesat dam)
تحليل تأثير سماكة النواة العمودية على استقرار السدود الترابية (حالة سد الدويسات)
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فاطمة فويتي( باحث )
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في هذا البحث تم دراسة تقييم استقرار سد الدويسات ذي النواة الشاقولية و الارتفاع 33 م، ميل الجانب الخلفي 1V:2.75H و ميل الجانب الأمامي 1V:3H ، كما سيتم دراسة تغير سماكة النواة من 1V:0.25H إلى 1V:2.0H و تأثيرها على استقرار جانبي السد الأمامي و الخلفي و ذلك لثلاث حالات تصميمية هي خلال فترة بناء السد، التسرب المستقر، و التفريغ السريع، و ذلك باستخدام طريقة التوازن الحدية العامة و حزمة البرامج GeoStudio. و قد تبين من التحليل أته بتغير سماكة النواة الشاقولية للسد، فإن النواة ذات السماكة الأقل تعطي استقراراً أكبر و أن الزيادة في سماكة النواة لميول أكبر تسبب انخفاضاً حاداً لعامل أمان الوجهين الأمامي و الخلفي للحالات التصميمية الثلاثة الآنفة الذكر.
Therefore in this paper we will present the stability analysis carried out on the Dwesat dam with vertical core, its high is 33m, the downstream slope of 1V:2.75H and the upstream slope of 1V:3.0H. Thickness of the vertical core was varied from 1V:0.25H to 1V:2.0H, and also present the effect of the varied thickness on slope stability for both upstream and downstream under three design conditions i.e. during and end of construction, steady state seepage and rapid draw down by General Limit Equilibrium Method using GeoStudio software. It was observed from the analysis that by varying the thickness of vertical core of earth dam, thinner core up to 1V:1.30H gives more stability and further increase in thickness of core tends to sharp decline in factor of safety for both upstream and downstream slope under different design conditions.
References used
BISHOP A.W., BLIGHT G.E., -Some aspects of effective Stress in Saturated and unsaturated soils, Geotechnique, VOL. 13 , No 3, 1963
BISHOP A.W., MORGENSTREN N.R., - Stability coefficients for earth slopes, Geotechnique , VOL. 10 , No. 4. 1960
FREDLUND D. G., RAHARDIO H., - Soil Mechanics for un saturated soils, John wiley & sons , Newyork. 1993
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This research includes analytical study by Finite Element Method about the effect of
earthquakes in the stability of ALBASEL DAM, so we have set a numerical model suitable
by using programs Slope/W, Quake/W. We run the model and we got the results
of the
simulation, which summarized in calculation factors of safety for verification the final
stability of the dam under the effect of different intensity earthquakes. And then were
compared between the two cases static and dynamic model showing the effect of the shear
variables of the soil angle of internal friction and tendency of slops dam and the different
situations of the lake water levels and the high of dam in addition to the effect of the
construction material of the dam on the stability of the body of the dam.
After the study each case depending on the parameters, that are entered, and based
on the resulting factors of safety, the diagrams are painted to appear the positive or the
negative effects to increase or decrease any variable of the dam variables in each of the
static case and the dynamic case. And then we studied the effect of seismic Amplification
resulting from the body of the dam on both the two horizontal and vertical component of
seismic acceleration. The results will help us in a perfect choice for variables of
Embankment dams for design.
The scientific and practical value of this research appears in recognizing the characteristics of the clay soil, which is located in Alnabeck, and used in constructing ALwagar earth fill dam. We will study five samples chosen from the materials site
Hofar ALmlagea and which will be used in constructing ALwagar earth fill dam through which some Geo-geometrical characteristics like (Liquid Limit, Plasticity Limit, plasticity index, Consistency Index, Liquidity Index, Clay activity, collapse degree) will be determined.
Depending on the Results of this study, we used international classifications (Casagrande classification – Unified Soil Classification System) to study the soil of the studied area. We made use of the results of the experimental study to determine the position of soil according to the international classification, and we suggested some solutions to improve the characteristics of the soil which is used in constructing soil dams.
The stability of the upstream shell of the dams is changed under the rapid drawdown
condition where the pore water pressure has a different values according to the soil
permeability. This paper considers the stability of the upstream shell of the "
Braddon" dam
with many types of soil and analyses each type under two rapid drawdown programs, the
first program is when the discharge happens, according to the irrigation outlet by 25 m3/s,
and the second program is when the discharge happens according to the tunnel conversion
of the river by 500 m3/s. The obtained results show, that the stability of the upper slope
under considered boundary conditions changed according to the soil type. Some soil have
good stability factor while other soil collapsed .Accordingly, we can conclude that the
type of soil of the upper dam slope is important and we could chose the appropriate type
which does not cause dangerous during the rapid drawdown. Also the study shows that:
the highest values of the safety factors result when the slopes are formed of high
permeability soils as well as the slopes of homogeneous soil, while the soils formed of
materials between them appeared decreasing values of safety factors.
This research study the cause failure earth dams After that it show the
more important problems which dams exposure.
During its construction and compassingthe importance causes of this
case and how we can processing it , and show also the necessar
y of
earth dams observerand the necessary reportsto showing that the work
of dam is good.
The research also discusses the analysis of earth dam using the Geo
slope program.
We have chosen many parameters as total stresses, vertical strain , and
pore water pressure to study change of this parameters with elevation
in the upstream , downstream , and core of dam and draw the requisite
graphsgraphs to compare this design values with reading of observer
devices to be sure of typical work of dam.
Finaly we showing the results and suggest many recommendations.
Asphalt concrete was used for the first time in Syria as a tightening material for dam
Sourani. It was used in this dam as a surface facing on the front slope.
Use of asphaltic concrete under climatic conditions prevailing in Syria, particularly
h
igh temperatures, is discussed in the paper. To achieve this goal, a number of bituminous
concrete mixes, designed using the same constituent components in Sourani dam, were
experimentally tested and analyzed. To determine the effect of the expected maximum
temperatures for Sourani dam, a program depending on Energy balance was developed.
Possible methods of reducing the effect of the high temperature in order to increase
the stability of the asphalt surface facing are analyzed. In this context, the facing was
plastered by a light-color, which led to a decrease in the temperature of the asphalt surface
facing by about 20 degrees Celsius. The facing was also plastered by placing a concrete
layer above it, which led to a decrease in the temperature of the asphalt surface facing by
about 25 degrees Celsius.
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