design of piled raft foundations. مشاركة لبشة الأوتاد الخوازيق و التربة في تحمل حمولات اللبشة

1
Dr. Hammida
‫اللبشة‬–‫العامة‬ ‫الحصيرة‬
) ‫األوتاد‬ ( ‫الخوازيق‬ ‫-لبشة‬
‫والتربة‬ )‫األوتاد‬ (‫الخوازيق‬ ‫لبشة‬
Mat foundation- Raft foundation-
Mat- Pile Foundation-
Mat & Piles Foundation-

3
Do you have access to a computer program that can do a finite elements analysis?
If so, you can model the mat as a concrete plate, subdivided into finite elements, on soil
springs.
Check service load soil bearing pressures qs against the allowable soil bearing
pressure q , and design the mat for factored pressures.
A

4
Check service load soil bearing pressures: qs = K*∆
∆= Deflection in joint spring
K= sprink stiffness or Module of sup grade
If no soil report for Module of sup grade use K= 100 q
Check: qs < q
If you design this by hand? you must assume the mat is
infinitely rigid.
First off all, you calculate the soil bearing pressure at all four corners of the mat
(check these against the allowable soil bearing pressure).

5
Then, using factored soil bearing pressures qu ,
design the concrete mat as a two way flat slab or- two way solid slab-
With to layer of steal top and bottom not less than Minimum reinforcement
Conventional Method
The basic assumptions in conventional method are:
Foundation is rigid relative to supporting soil and compressible soil is relatively shallow.
 The bearing pressure is assumed to be uniform such that centroid of the bearing
pressure coincides with the line of action of the resultant of all forces acting on the
foundation. In case of mat foundation it is difficult to coincide the line of action of resultant
force with the line of action of the soil pressure and there always exists some eccentricity.
The procedure for the conventional design of a raft foundation consists of the following
steps.
o Determine the line of action of all the loads acting on the raft as shown in Fig. 1. The self
weight of raft is not considered, as it is taken directly by the soil.
o Determine pressure distribution.
In general, a mat foundation is subjected to eccentricity on both x and y axis, then a
situation as shown in Fig. 1 occurs and in such case, the pressure, q is given by,
Where, ex is the eccentricity along x-axis, ey is the eccentricity along y-axis, Q is the
resultant of all the column loads, Ixx is the moment of inertia about y-axis and y is the

6
distance of the point in y-axis from the neutral axis, Iyy is the moment of inertia about x-axis
and x is the distance of the point in x-axis from the neutral axis.
The maximum soil pressure as obtained from the above equation should be less than the
allowable soil pressure.
Settlement of Raft Foundation
The settlement is not a problem for raft on sands as allowable bearing capacity is
computed on the basis of settlement criteria.
However, settlement is of great concern when a raft rests on a deposit of normally
consolidated clay.
The net foundation pressure for computing settlement is taken as:
qns = (Q/A) – γ×Df ———– (1)
The pressure in the Eq. (1) shall not cause settlement in excess of permissible
value. If settlement exceeds the permissible limits, the foundation pressure should
be reduced either by increasing the area under the structures or by increasing the
depth of raft or by providing one or more basement.
The base area of raft cannot be increased due to space limitation and hence the
only practical method to limit the settlement in order to obtain a required factor of
safety is to lower the elevation of the raft.
If this procedure does not bring the settlement within the permissible limits then a
deep foundation should be provided.

7
dvantage of Raft-Mat Foundation in Weak Soil
Raft or Mat foundation cover entire floor area of structure; it is a combined foundation
which support all columns and walls (structural or non-structural). We will discuss
here about advantage of raft foundation in weak soil i.e. soil having very low bearing
capacity.
In such condition raft foundation serves three advantages like-
Ultimate bearing capacity as proposed by different researchers have
relation with
width of foundation such that with increase in width ultimate bearing
capacity is also
increased which brings deeper layers of soil in effective zone.
The settlement of foundation is also decreased with increasing depth.
The erratic behavior of foundation soil, offers always differential settlement.
This type of settlement is very harmful to structure as stresses concentrated
at weak points of framing system which opens cracks and often lead to
failure.

8
Raft foundation minimizes differential settlement and offer act as a bridge
over cavities.
Structures have a limiting value of differential settlement not to be
undergone damage.
It is found that differential settlement measured in different parts of
elements supported by raft foundation is significantly lower than identical
structure supported on individual
footings.
It is interesting to notice that maximum settlement or total settlement has
found same.
Again for raft or mat foundation allowable settlement is also considered more
than allowable settlement for structures supported on individual footing; in the other
word, this foundation permits higher bearing capacity in this situation.
Now we have to consider depth of soil layer having poor bearing capacity.
When deeper soil layers have very poor bearing property, increasing width of
foundation (like raft) will not always offer higher bearing capacity.
We know zone of influence of foundation is a function of foundation width.
So where soil at shallow layer have comparatively fair bearing capacity than underlain
deeper soil layers (having much weaker soils), it is recommended to use individual
footings as zone of influence of foundation is kept within relatively stronger layer at
the top.
So, mat foundation is discouraged in this situation

9
How are Raft Foundations Used to Reduce Settlement?
rafts are nothing but a flat slab reinforced with steel.
In the design purpose equivalent frame method of flat plate/slab is used as
recommendation of some codes. When C.G. (center of gravity) of loads
arrived
from individual columns or share walls coincide with raft’s centroid, the
upward reaction from soil becomes uniform.
The uniform upward reaction is equals to the sum of all loads from the
columns and other members divided by area occupied by raft.
It is important to note that in structural design self weight of raft is not
considered as self weight is supposed to rest directly on the subsoil.
Here no consideration for differential settlement (moment and shear form
differential settlement) is accounted and the effects of differential
settlement are compensated by using heavier reinforced section than that
required from above analysis.
In case of compressible soils, sometimes the total raft foundation is made
compensated foundation.
Now question is what is compensated foundation?
The answer is the raft slab is provided at such a depth that the weight of soil
excavated is equal to the weight of raft slab plus that of structure
to be supported.
Theoretically there should be no settlement as no pressure is increased
at that level.

10
Practically the settlement is also insignificant.
But total compensation is often impossible or impractical as weight
of structure often becomes too large.
In this situation partial compensation is used so that the settlement is in
Tolerable limit.
so far we considered differential properties of soils.
But if loads from different columns are not distributed uniformly the raft
Should be stiffened by T-beams connecting the raft with the stems.
In case of subsoil that is susceptible to large differential settlement this stiffening
Method is also applicable.
What is Raft Foundation?
Difference between Raft Foundations and Mat Foundation
Don't confuse about raft and mat foundation. Raft foundation is
mat foundation. Now what is raft foundation?
Raft foundation is a thick concrete slab reinforced with steel which covers the
entire contact area of the structure like a thick floor. Sometimes area covered by
raft may be greater than the contact area depending on the bearing capacity of
the soil underneath. The reinforcing bars runs normal to each other in both top
and bottom layers of steel reinforcement.
Sometimes inverted main beams and secondary beams are used to carry column
loads that require thicker foundation slab considering economy of the structure.
Both beams cast monolithically with raft slab.
Now I shall discuss where raft foundations are required.
Raft foundation is required where soils have low bearing capacity and have to support
heavy structural loads.
Normally structures on marshy land, soft clay and land that are made up of sanitary
land fill or other materials (like debris, unconsolidated soil and solid waste etc.
where differential settlement is suspected)-require raft foundation.

11
Raft foundations are preferred in the soil that are suspected to subsidence.
Subsidence may occur from different sources like change in ground water level due to
climatic change specially in case expansive soil or foundation in mining area.
In one words, where deep foundation like pile foundation are not economical and
feasible and isolated column footing is impracticable due to large footing size or over-
lapping of neighbor footing , raft foundation is the economical solution.
Raft Foundation

13
The types of mat foundation commonly employed are
Flat plate mat
Plate thickened under columns
Two-way beam and slab
Plate with pedestal
Rigid frame mat
Piled raft

31
‫الخطوات‬‫والخوازيق‬ ‫اللبشة‬ ‫تصميم‬ ‫في‬ ‫الالزمة‬
‫بمقدار‬ ‫نصعدها‬ ‫الكلية‬ ‫الشاقولية‬ ‫الحموالت‬ ‫قيمة‬ ‫معرفة‬ ‫بعد‬01%‫وحموالت‬ ‫الحصيرة‬ ‫مركز‬ ‫بين‬ ‫والالمركزية‬ ‫العزوم‬ ‫تواجد‬ ‫مقابل‬
‫والجدران‬ ‫األعمدة‬‫التربة‬ ‫تقرير‬ ‫من‬ ‫المعطاة‬ ‫األعظمية‬ ‫الوتد‬ ‫حمولة‬ ‫على‬ ‫ونقسم‬‫الال‬ ‫الكلية‬ ‫األوتاد‬ ‫عدد‬ ‫نوجد‬ ‫ومنها‬‫جاء‬ ‫كما‬ ‫ونتابع‬ ‫زم‬
‫اعاله‬
-‫الخازوق‬ ‫ومن‬ ‫العامود‬ ‫من‬ ‫الثقب‬ ‫اجهاد‬ ‫على‬ ‫اللبشة‬ ‫تدقيق‬ ‫يجب‬
-‫شادة‬ ‫اجهادات‬ ‫الخوازيق‬ ‫بعض‬ ‫في‬ ‫سالب‬ ‫فعل‬ ‫رد‬ ‫نرى‬ ‫قد‬
‫وغيرها‬ ‫كبيرة‬ ‫زلزالية‬ ‫افقية‬ ‫قوى‬ ‫وجود‬ ‫حال‬ ‫في‬‫وكذلك‬ ‫الشد‬ ‫لقوة‬ ‫الخازوق‬ ‫تسليح‬ ‫حساب‬ ‫يجب‬ ‫الحالة‬ ‫هذه‬ ‫في‬
‫الخازوق‬ ‫جوانب‬ ‫على‬ ‫االحتكاك‬ ‫قوة‬> up lift
-‫اللبشة‬ ‫على‬ ‫قصية‬ ‫افقية‬ ‫قوى‬ ‫تواجد‬ ‫حال‬ ‫في‬
‫القص‬ ‫قوة‬ ‫من‬ ‫الخازوق‬ ‫حصة‬ ‫حساب‬ ‫يجب‬v‫وئلك‬‫الخوازيق‬ ‫عدد‬ ‫على‬ ‫الكلي‬ ‫القاعدي‬ ‫القص‬ ‫قيمة‬ ‫بتقسيم‬
-‫للخازوق‬ ‫الحر‬ ‫الطول‬ ‫معرفة‬ ‫يجب‬h‫الوثاقة‬ ‫ومكان‬
‫عادة‬ ‫التربة‬ ‫حيث‬ ‫اللبشة‬ ‫اسفل‬ ‫عن‬ ‫للخازوق‬‫التربة‬ ‫تقرير‬ ‫من‬ ‫رخوة‬‫الخازوق‬ ‫رأس‬ ‫على‬ ‫العزم‬ ‫ونوجد‬v*h=
-‫تواجدت‬ ‫اذا‬ ‫والعزم‬ ‫والقص‬ ‫الشد‬ ‫قوة‬ ‫على‬ ‫الخازوق‬ ‫رأس‬ ‫وحساب‬ ‫تدقيق‬‫المحورية‬ ‫للحموالت‬ ‫باالضافة‬
‫التربة‬ ‫على‬ ‫تصميمها‬ ‫يشابه‬ ‫خوازيق‬ ‫على‬ ‫اللبشة‬ ‫تصميم‬
‫الشاقولية‬ ‫الحموالت‬ ‫على‬ ‫والخوازيق‬ ‫اللبشة‬ ‫تصمم‬ ‫ان‬ ‫ويجب‬‫الزلزالية‬ ‫واألفقية‬
-‫تواجد‬ ‫حال‬ ‫وفي‬v =‫األفقية‬ ‫القاعدي‬ ‫القص‬ ‫قوة‬
‫و‬M=‫القاعدة‬ ‫على‬ ‫االفقية‬ ‫القوى‬ ‫من‬ ‫االنقالب‬ ‫عزم‬
P =‫للبناء‬ ‫الكلي‬ ‫الوزن‬
-‫الخازوق‬ ‫على‬ ‫الشد‬ ‫او‬ ‫الضغط‬ ‫قوة‬ ‫نوجد‬F:
F= P/n +_ M*di / sum )di2(
n=‫اسفل‬ ‫بانتظام‬ ‫موزع‬ ‫الكلي‬ ‫الخوازيق‬ ‫عدد‬‫اللبشة‬
d=‫اللبشة‬ ‫ثقل‬ ‫مركز‬ ‫عن‬ ‫خازوق‬ ‫كل‬ ‫بعد‬
sum d2=‫البعد‬ ‫مربع‬ ‫مجموع‬‫اللبشة‬ ‫ثقل‬ ‫مركز‬ ‫عن‬
-‫المحورية‬ ‫القوة‬ ‫اوالشد‬ ‫بالضغط‬ ‫يتحمل‬ ‫ان‬ ‫الخازوق‬ ‫على‬F
‫حيث‬‫القطر‬ ‫نزيد‬ ‫او‬ ‫الخوازيق‬ ‫عدد‬ ‫نزيد‬
-‫اللبشة‬ ‫اعلى‬ ‫العامود‬ ‫حمولة‬ ‫من‬ ‫بالثقب‬ ‫اللبشة‬ ‫تدقيق‬
‫حمولة‬ ‫ومن‬‫اسفلها‬ ‫الخازوق‬
-‫وجدت‬ ‫ان‬ ‫األفقية‬ ‫الزلزالية‬ ‫القوى‬ ‫تقاوم‬ ‫ان‬ ‫يجب‬ ‫األوتاد‬
-‫ويحدث‬ ‫يتحرك‬ ‫سوف‬ ‫رخوة‬ ‫الخازوق‬ ‫رأس‬ ‫حول‬ ‫التربة‬ ‫ان‬ ‫وبما‬
‫الخازوق‬ ‫اعلى‬ ‫انحناء‬ ‫عزم‬
‫الحر‬ ‫الخازوق‬ ‫رأس‬ ‫طول‬ ‫وعادة‬=‫اللبشة‬ ‫اسفل‬ ‫من‬ ‫امتر‬
‫ومقدارالعزم‬=‫امتر‬* v1‫الخازوق‬ ‫حصة‬
‫رأس‬ ‫تصميم‬ ‫ويجب‬‫ذلك‬ ‫على‬ ‫الخازوق‬

32
--‫حساب‬‫لبشة‬‫الخوازيق‬‫يدويا‬
-‫محيط‬ ‫من‬ ‫الثقب‬ ‫اجهاد‬ ‫تحقيق‬ ‫من‬ ‫اللبشة‬ ‫سماكة‬ ‫نحدد‬ ‫عادة‬‫الثقب‬ ‫يقاوم‬ ‫تسليح‬ ‫وضع‬ ‫يفضل‬ ‫وال‬ ‫الوتد‬ ‫او‬ ‫للعامود‬ ‫الثقب‬
-‫اللبشة‬ ‫على‬ ‫بانتظام‬ ‫موزعة‬ ‫حمولة‬ ‫الى‬ ‫المركزة‬ ‫الخازوق‬ ‫حمولة‬ ‫تحويل‬‫الوتد‬ ‫حمولة‬ ‫بتصعيد‬ ‫نقوم‬‫بمقدار‬%01
‫المحصورة‬ ‫المساحة‬ ‫على‬ ‫وتقسميها‬‫طن‬ ‫التحمل‬ ‫على‬ ‫لنحصل‬ ‫الألوتاد‬ ‫بين‬/‫م‬2‫كما‬ ‫اصوال‬ ‫التسليح‬ ‫ونوجد‬ ‫ونتابع‬
‫العادية‬ ‫اللبشات‬ ‫في‬
-‫األصغري‬ ‫عن‬ ‫التسليح‬ ‫يقل‬ ‫ال‬
‫ايقاف‬ ‫دون‬ ‫المجازات‬ ‫طول‬ ‫كامل‬ ‫على‬ ‫والسفلي‬ ‫العلوي‬ ‫التسليح‬ ‫ويمتد‬
‫القضبان‬ ‫بعض‬
***‫ال‬ ‫او‬ ‫الرخوة‬ ‫الترب‬ ‫حال‬ ‫في‬‫طينية‬
‫اللبشة‬ ‫محيط‬ ‫على‬ ‫تزرع‬ ‫مائلة‬ ‫بخوازيق‬ ‫االستعانة‬ ‫يجب‬
‫والزلزالية‬ ‫االفقية‬ ‫القوى‬ ‫لمقاومة‬
‫الخوازيق‬ ‫لبشة‬ ‫حساب‬(‫األوتاد‬)‫بالحاسب‬
-‫الخوازيق‬ ‫صالبة‬ ‫ايجاد‬k stiffness)(‫ب‬ ‫الخازوق‬ ‫عن‬ ‫والتعويض‬spring
-‫الحركة‬ ‫من‬ ‫وممنوع‬ ‫التربة‬ ‫في‬ ‫ومدفون‬ ‫موثوق‬ ‫الخازوق‬ ‫ان‬ ‫بما‬‫األفقية‬‫تميثله‬ ‫يمكن‬ ‫لذلك‬ ‫الرأسى‬ ‫والهبوط‬ ‫الحركة‬ ‫اال‬
‫ب‬spring
translation + assign joint spring‫فقط‬ ‫الشاقولي‬ ‫المحور‬ ‫مع‬
-‫الصالبة‬ ‫عامل‬ ‫تعين‬ ‫يمكن‬K‫واوتاد‬ ‫لبشة‬ ‫حال‬ ‫في‬ ‫مسموح‬ ‫هبوط‬ ‫فرض‬ ‫من‬=0‫سم‬
K=‫للخازوق‬ ‫التشغيلي‬ ‫الحمل‬‫الهبوط‬ ‫علي‬ ‫مقسوما‬ ‫بالطن‬‫المحسوبللخازوق‬‫ويمكن‬ ‫بالمتر‬
‫الهبوط‬ ‫اخذ‬=0‫سم‬(10.‫متر‬)‫التربه‬ ‫تقرير‬ ‫من‬ ‫معرفته‬ ‫عدم‬ ‫حالة‬ ‫في‬
-‫التشغيلي‬ ‫الحمل‬ ‫كان‬ ‫اذا‬ ‫فمثال‬=01‫طن‬k=70/.01 =7000
-‫قانون‬ ‫من‬ ‫ويمكن‬‫تح‬‫مل‬‫المسموح‬ ‫التربة‬q=‫ولدين‬‫ا‬= 100 qk
K=100*70 = 7000 tlm
-‫الوتد‬ ‫صالبة‬ ‫لتعين‬ ‫اخرى‬ ‫طريقة‬‫للتربة‬ ‫فني‬ ‫تقرير‬ ‫تواجد‬ ‫عدم‬ ‫حال‬ ‫في‬
‫يتم‬‫اللبشة‬ ‫تحت‬ ‫االوتاد‬ ‫تمثيل‬Spring‫ومنه‬‫الوتد‬ ‫قساوة‬K
D=PL/EA
displacement or settlement=D‫للوتد‬ ‫الشاقولي‬ ‫االنزياح‬
P‫الوتد‬ ‫تحمل‬ ‫قدرة‬-‫الوتد‬ ‫قساوة‬K=P/D-K = EA/L
‫للوتد‬ ‫المسموح‬ ‫االنزياح‬=0%‫الوتد‬ ‫قطر‬ ‫من‬
D=0.01*d
d‫الوتد‬ ‫قطر‬.

33
-‫صغيرة‬ ‫بمربعات‬ ‫اللبشة‬ ‫شبكة‬ ‫تقسيم‬ ‫يفضل‬1.0*1.0
‫الخوازيق‬ ‫ومسافات‬ ‫التقاطع‬ ‫نقاط‬ ‫في‬ ‫الفروقات‬ ‫وتقريب‬ ‫الخوازيق‬ ‫تموضع‬ ‫المكانية‬
-‫ب‬ ‫خازوق‬ ‫كل‬ ‫يمثل‬spring‫وصالبته‬k
-‫الجدار‬ ‫او‬ ‫العامود‬ ‫اسفل‬ ‫يكون‬ ‫ان‬ ‫شرطا‬ ‫ليس‬spring‫المهم‬ ‫ولكن‬
‫يقع‬ ‫ان‬‫المربعات‬ ‫وتقاطع‬ ‫عقد‬ ‫في‬ ‫الجدار‬ ‫او‬ ‫العامود‬ ‫وينطبق‬
-‫الحاسب‬ ‫على‬ ‫التحليل‬ ‫اجراء‬ ‫بعد‬
-‫الخازوق‬ ‫وهبوط‬ ‫االنتقال‬ ‫وقيمة‬ ‫واألفقي‬ ‫الشاقولي‬ ‫الخازوق‬ ‫على‬ ‫الفعل‬ ‫رد‬ ‫ايجاد‬ ‫يجب‬
-‫التربة‬ ‫تقرير‬ ‫وفق‬ ‫المسموح‬ ‫ضمن‬ ‫وانه‬
-‫رأس‬ ‫لحساب‬ ‫والعزوم‬ ‫الخازوق‬ ‫على‬ ‫األفقي‬ ‫الفعل‬ ‫رد‬ ‫تدقيق‬‫سابقا‬ ‫رأينا‬ ‫كما‬ ‫الخازوق‬
-‫وتحقيق‬ ‫الالزم‬ ‫التسليح‬ ‫وايجاد‬ ‫اللبشة‬ ‫تصميم‬ ‫طلب‬‫ا‬‫الثقب‬ ‫جهاد‬
‫الخازوق‬ ‫تسليح‬(‫الوتد‬)
-‫مقطعه‬ ‫من‬ ‫األصغري‬ ‫التسليح‬ ‫نسبة‬ ‫عن‬ ‫يقل‬ ‫وال‬ ‫بالعامود‬ ‫اسوة‬ ‫بالكامل‬ ‫الخازوق‬ ‫تسليح‬ ‫يجب‬
-‫وطولي‬ ‫حلزوني‬ ‫عرضي‬ ‫اضافي‬ ‫بتسليح‬ ‫العلوي‬ ‫القسم‬ ‫تسليح‬ ‫ويجب‬‫القص‬ ‫قوى‬ ‫لمقاومة‬
‫وجدت‬ ‫ان‬ ‫االنحناء‬ ‫وعزوم‬
-‫المطلوب‬ ‫حال‬ ‫في‬ ‫الخازوق‬ ‫رأس‬ ‫في‬ ‫الالزم‬ ‫التسليح‬ ‫اضافة‬ ‫يجب‬ ‫كذلك‬
‫للرفع‬ ‫الخازوق‬ ‫تحمل‬ ‫قوة‬ ‫ومعرفة‬ ‫الخوازيق‬ ‫استالم‬ ‫عند‬ ‫الموقع‬ ‫في‬ ‫الشد‬ ‫تجربة‬ ‫اجراء‬uplift
-‫الخواز‬ ‫واختبار‬ ‫تجارب‬‫ي‬‫ق‬(‫األوتاد‬)
-‫واختبارات‬ ‫تجارب‬ ‫هناك‬‫والتربة‬ ‫الخازوق‬ ‫نوع‬ ‫حسب‬ ‫تختلف‬
‫الشروط‬ ‫ودفتر‬ ‫المخططات‬ ‫على‬ ‫لحظها‬ ‫ويجب‬ ‫الخازوق‬ ‫من‬ ‫تحقيقه‬ ‫المطلوب‬ ‫والعمل‬
‫المشروع‬ ‫لمناقصة‬ ‫الفنية‬
-‫والتجارب‬ ‫االختبارات‬ ‫هذه‬ ‫واهم‬
1-‫الخوازيق‬ ‫بتنفيذ‬ ‫البدء‬ ‫قبل‬ ‫اجرائها‬ ‫ويجب‬ ‫الخازوق‬ ‫اختبار‬ ‫تجربة‬
‫لما‬ ‫طبقا‬ ‫واحد‬ ‫خازوق‬ ‫تنفيذ‬ ‫يتم‬ ‫حيث‬‫التربة‬ ‫وتقرير‬ ‫المخططات‬ ‫في‬ ‫جاء‬‫األعظمي‬ ‫والتحمل‬ ‫وقطره‬ ‫الخازوق‬ ‫طول‬ ‫حول‬
‫المسموح‬ ‫الهبوط‬ ‫ومقدار‬‫التربة‬ ‫ضمن‬ ‫المطلوبة‬ ‫االعماق‬ ‫الى‬ ‫والوصول‬‫جهة‬ ‫موافقة‬ ‫وأخذ‬ ‫ذلك‬ ‫صحة‬ ‫من‬ ‫التاكد‬ ‫وبعد‬
‫المسؤول‬ ‫والمهندس‬ ‫االشراف‬‫الخوازيق‬ ‫باقي‬ ‫وتنفيذ‬ ‫العمل‬ ‫يتم‬
2-‫هي‬ ‫الثانية‬ ‫التجربة‬‫التصميم‬ ‫متطلبات‬ ‫وفق‬ ‫اختبارية‬‫شادة‬ ‫رفع‬ ‫قوى‬ ‫وتواجد‬
‫قوى‬ ‫وتواجد‬uplift‫تحقيها‬ ‫والمفروض‬ ‫المخططات‬ ‫على‬ ‫وشدتها‬ ‫قيمتها‬ ‫تحدد‬‫مع‬ ‫الخازوق‬ ‫لميحط‬ ‫حتكاك‬ ‫اال‬ ‫قوى‬ ‫من‬
‫واحد‬ ‫وتد‬ ‫على‬ ‫االختبار‬ ‫اجراء‬ ‫والمفروض‬ ‫التربة‬‫الخوازيق‬ ‫باقي‬ ‫تنفيذ‬ ‫ثم‬ ‫الشروع‬ ‫قبل‬
3-‫الثالث‬ ‫واالختبار‬ ‫التجربة‬‫والمعايرة‬ ‫األوتاد‬ ‫استالم‬ ‫تجربة‬ ‫هي‬
‫والشروط‬ ‫المواصفات‬ ‫مع‬ ‫التنفيذ‬ ‫اعمال‬ ‫ومطابقة‬ ‫الفعلي‬ ‫الهبوط‬ ‫ومقدار‬ ‫الخازوق‬ ‫تحمل‬ ‫لقدرة‬‫المخططات‬ ‫في‬ ‫المبينة‬ ‫الفنية‬

34
‫الخوازيق‬ ‫جميع‬ ‫على‬ ‫تجري‬ ‫ال‬ ‫التجربة‬ ‫هذه‬ ‫وطبعا‬ ‫الشروط‬ ‫ودافتر‬‫العدد‬ ‫من‬ ‫بنسبة‬ ‫تحدد‬ ‫عشوائية‬ ‫عينة‬ ‫على‬ ‫بل‬ ‫المنفذة‬
‫الكلي‬‫المنفذ‬
4-‫خاص‬ ‫فني‬ ‫مراقب‬ ‫تكليف‬ ‫االشراف‬ ‫وجهة‬ ‫االدارة‬ ‫على‬
‫والتجارب‬ ‫االختبارات‬ ‫وصحة‬ ‫المواد‬ ‫جودة‬ ‫وفق‬ ‫الصحيح‬ ‫والتنفيذ‬ ‫المراقبة‬ ‫لتأمين‬
--**‫الشدة‬ ‫ذات‬ ‫الزلزالية‬ ‫المناطق‬ ‫في‬ ‫الواقعة‬ ‫المشاريع‬ ‫معظم‬
‫مناطق‬ ‫الخفيفة‬0-2‫الزلزالية‬ ‫القوى‬ ‫تكون‬ ‫العادية‬ ‫واألبنية‬‫صغيرة‬ ‫القاعدة‬ ‫على‬ ‫والعزوم‬
‫و‬ ‫رفع‬ ‫لقوى‬ ‫تأثير‬ ‫وال‬uplift‫التجربة‬ ‫الجراء‬ ‫داعي‬ ‫ال‬ ‫لذلك‬
-‫حدوث‬ ‫الى‬ ‫ستودي‬ ‫القاعدة‬ ‫على‬ ‫تعمل‬ ‫عزوم‬ ‫وتواجد‬ ‫العالية‬ ‫البرجية‬ ‫األبنية‬ ‫اما‬‫شادة‬ ‫ضاغطة‬ ‫قوى‬
‫وتواجد‬uplift‫األعلي‬ ‫الى‬ ‫الخازوق‬ ‫يشد‬‫تجربة‬ ‫عمل‬ ‫فيجب‬uplift‫واحد‬ ‫خازوق‬ ‫على‬‫البدء‬ ‫قبل‬‫بتنفيذ‬
‫الخوازيق‬‫تواجد‬ ‫حالة‬ ‫على‬ ‫ال‬ ‫ام‬ ‫اجراءها‬ ‫يعتمد‬ ‫التجربة‬ ‫هذه‬ ‫اذن‬uplift‫ال‬ ‫ام‬.
‫المياه‬ ‫منسوب‬ ‫تواجد‬
‫يسمى‬ ‫ما‬ ‫او‬ ‫الجوفية‬ ‫المياه‬ ‫مستوى‬ ‫تنزيل‬ ‫عملية‬Dewatering
-‫ف‬‫اللبشة‬ ‫مستوي‬ ‫من‬ ‫اعلى‬ ‫المياه‬ ‫ومنسوب‬ ‫مياه‬ ‫وجود‬ ‫حال‬ ‫ي‬
‫الى‬ ‫وتصريفها‬ ‫بضخها‬ ‫المياه‬ ‫منسوب‬ ‫تنزيل‬ ‫يجب‬‫مجرور‬ ‫اقرب‬
‫يستمر‬ ‫المياه‬ ‫وضخ‬ ‫وشفط‬ ‫واألوتاد‬ ‫اللبشة‬ ‫تنفيذ‬ ‫لإلمكانية‬‫الوتد‬ ‫محيط‬ ‫حول‬ ‫التربة‬ ‫تفقد‬ ‫فالمياه‬ ‫التنفيذ‬ ‫مدة‬ ‫طوال‬
‫تعمل‬ ‫وال‬ ‫الترب‬ ‫بعض‬ ‫في‬ ‫اوتقللها‬ ‫االحتكاك‬ ‫خاصية‬‫لم‬ ‫اذا‬ ‫الخوازيق‬ ‫وتنقلع‬ ‫اللبشة‬ ‫ترتفع‬ ‫وقد‬ ‫الشد‬ ‫على‬
‫اسفل‬ ‫حتى‬ ‫المستوي‬ ‫وتنزيل‬ ‫المياه‬ ‫وشفط‬ ‫ضخ‬ ‫يتم‬‫اللبشة‬
-‫حيث‬‫وعمل‬ ‫المياه‬ ‫شفط‬ ‫دون‬ ‫اللبشة‬ ‫حتى‬ ‫وال‬ ‫الخوازيق‬ ‫تنفيذ‬ ‫اليمكن‬Dewatering

38
Raft Foundations-Design of piled
-(‫شارك‬‫لبشة‬‫التربة‬‫مع‬‫الخوازيق‬)‫اوتاد‬‫او‬‫شارك‬‫لبشة‬‫الخوازيق‬‫مع‬‫التربة‬
‫توفر‬‫تقريبا‬30%‫من‬‫عدد‬‫الخوازيق‬
‫تصميم‬‫اللبشة‬‫الحصيرة‬(‫مع‬‫مشاركة‬‫الخوازيق‬)‫ألوتاد‬‫و‬‫التربة‬‫في‬‫تحمل‬‫األ‬‫وزان‬‫والجهود‬‫من‬‫الحمو‬‫ال‬‫ت‬
‫الشاقولية‬‫والزلزالية‬‫على‬‫اللبشة‬
-‫من‬‫اهم‬‫فقرات‬‫التصميم‬
‫يجب‬‫درأسة‬‫تأثير‬‫العمل‬‫المشترك‬‫بين‬‫هبوط‬‫الخازوق‬‫وهبوط‬‫التربة‬‫و‬‫ايجاد‬‫صيغة‬‫وعامل‬‫رد‬‫فعل‬
‫مشترك‬‫واحد‬‫بين‬‫عامل‬‫رد‬‫فعل‬‫التربة‬smart spring‫وعامل‬‫رد‬‫فعل‬‫الخازوق‬‫يسمى‬‫عامل‬‫النابض‬
‫الذكي‬‫ففي‬‫حال‬‫هبوط‬‫التربة‬‫اكبر‬‫من‬‫هبوط‬‫الوتد‬‫ستنتقل‬‫كامل‬‫الحمولة‬.‫الى‬‫الوتد‬‫وينهار‬‫الوتد‬‫او‬
‫اللبشة‬‫والعكس‬‫صحيح‬
‫والخوازيق‬ ‫التربة‬ ‫بتحمل‬ ‫اللبشة‬ ‫مشاركة‬
:
‫مقبول‬ ‫تحملها‬ ‫والتربة‬ ‫العالية‬ ‫األبنية‬ ‫حال‬ ‫في‬‫زرع‬ ‫يمكن‬ ‫لبشة‬ ‫اجل‬ ‫من‬ ‫كافي‬ ‫غير‬ ‫لكن‬‫اوتاد‬–‫خوازيق‬ -
‫الخوازيق‬ ‫مع‬ ‫التربة‬ ‫ومشاركة‬ ‫منتظم‬ ‫بتباعد‬ ‫شبكة‬ ‫بعمل‬ ‫كالعادة‬ ‫البرامج‬ ‫على‬ ‫تمثل‬ spring
‫لوحدها‬ ‫لبشة‬ ‫في‬ ‫كما‬ ‫التربة‬ ‫فعل‬ ‫رد‬ ‫عامل‬ ‫وادخال‬‫الخازوق‬ ‫فعل‬ ‫رد‬ ‫عامل‬ ‫يضاف‬ ‫وكذلك‬‫عند‬
‫خازوق‬ ‫كل‬
-‫الطريقة‬ ‫هذه‬ ‫تطبيق‬ ‫لكن‬‫المشترك‬ ‫العمل‬ ‫تأثير‬ ‫به‬ ‫يأخذ‬ ‫تربة‬ ‫تقرير‬ ‫يحتاج‬‫التربة‬ ‫هبوط‬ ‫بين‬
‫الفعل‬ ‫رد‬ ‫ومعامل‬ ‫الخازوق‬ ‫وهبوط‬‫الخازوق‬ ‫وحمولة‬ ‫المسموح‬ ‫التربة‬ ‫تحمل‬ ‫اعطاء‬ ‫ومنه‬
-‫به‬ ‫المعمول‬ ‫الكود‬ ‫ان‬ ‫من‬ ‫التأكد‬ ‫يجب‬ ‫كذلك‬‫والخازوق‬ ‫التربة‬ ‫مشاركة‬ ‫الطريقة‬ ‫بهذه‬ ‫يسمح‬‫في‬
‫التحمل‬‫المشتر‬‫ك‬
‫ت‬

39
-In situations where a raft foundation alone does not satisfy the design
requirements, it may be possible to enhance the
performance of the raft by the addition of piles.
- The use of a limited number of piles, strategically located, may improve
both the ultimate load capacity and the settlement and differential
settlement performance of the raft.
-

40
design of piled raft foundations.‫اللبشة‬ ‫حموالت‬ ‫تحمل‬ ‫في‬ ‫التربة‬ ‫و‬ ‫الخوازيق‬ ‫مشاركة‬
‫د‬.

43
of design should study the effect ofparagraphsOf the most important
nd find afalling pile and fall of the soil athe Joint Working Group of the
formula and factor common reaction one between subgrade reaction
worker and worker response pile reaction called springsmart spring
factor smart In the case of soil subsidence greater than the drop pile will
move full load
piles and breaks down to piles or mat and vice versa
In the event of high rises and soil carried acceptable but not enough for
the transplant can mat- piles-
Regular spacing and share the soil with piles represent the programs
work as usual spring network
And the introduction of sub grade reaction as factor in mat alone as well
as the added factor reaction pile at each pile

44
But the application of this method takes the soil report by the impact of
joint work between the soil decline and fall of the stake and the
coefficient of reaction and give him carrying a load of soil and allowed
the pile needs
Also must make sure that the applicable tag allows participation in this
way the soil and pile in the joint
Assume springs for soil and piles
getting modulus of sub grade
matsoilFor
∆ pile =∆ soil
for piles
K= 100 P p= pile Load
OR : ∆ = p*L/EA K=EA/L =P/ ∆
FOR ALLOW ∆ = 1cm k=P/0.01 = 100 P

46
‫األفقية‬ ‫لمقاومةالقوى‬ ‫مائلة‬ ‫خوازيق‬

design of piled raft foundations. مشاركة لبشة الأوتاد الخوازيق و التربة في تحمل حمولات اللبشة

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design of piled raft foundations. مشاركة لبشة الأوتاد الخوازيق و التربة في تحمل حمولات اللبشة