Critical levels for monitoring ground anchor systems provide essential safety checks during deep excavation projects. They define an alert level and work suspension level to monitor anchor loads. Exceeding the alert level requires close monitoring, while exceeding the work suspension level stops work. This case study of a large excavation project in Singapore demonstrates how critical level monitoring, conservative design parameters, and controlled pre-loading of anchors ensures the safety and performance of complex temporary earth retaining systems.
Vibro replacement stone columns are a ground improvement technique to improve the load bearing capacity and reduce the settlement of the soil. On many occasions, it is noted that the local soil is, by nature, unable to bear the proposed structure, so the use of ground improvement techniques may be necessary. Use of stone columns is one such technique. The stone column consists of crushed coarse aggregates of various sizes. The ratio in which the stones of different sizes will be mixed is decided by design criteria
The presentation illustrates a technique for ground improvement, Grouting. In India, grouting is still not being used very much. In this presentation, I have demonstrated the basic types of grouting, goals of ground improvement and two case studies of grouting.
Dense Bituminous Macadam (DBM) is a binder course used for roads with more number of heavy commercial vehicles and a close-graded premix material having a voids content of 5-10 per cent.
Vibro replacement stone columns are a ground improvement technique to improve the load bearing capacity and reduce the settlement of the soil. On many occasions, it is noted that the local soil is, by nature, unable to bear the proposed structure, so the use of ground improvement techniques may be necessary. Use of stone columns is one such technique. The stone column consists of crushed coarse aggregates of various sizes. The ratio in which the stones of different sizes will be mixed is decided by design criteria
The presentation illustrates a technique for ground improvement, Grouting. In India, grouting is still not being used very much. In this presentation, I have demonstrated the basic types of grouting, goals of ground improvement and two case studies of grouting.
Dense Bituminous Macadam (DBM) is a binder course used for roads with more number of heavy commercial vehicles and a close-graded premix material having a voids content of 5-10 per cent.
Overview of Soil Stabilization :Cement / Lime :PPTAniket Pateriya
Soil-cement is frequently used as a construction material for pipe bedding, slope protection, and road construction as a sub-base layer reinforcing and protecting the subgrade. It has good compressive and shear strength, but is brittle and has low tensile strength, so it is prone to forming cracks.
Lime can be used to treat soils to varying degrees, depending upon the objective. The least amount of treatment is used to dry and temporarily modify soils. Such treatment produces a working platform for construction or temporary roads. A greater degree of treatment supported by testing, design, and proper construction techniques--produces permanent structural stabilization of soils.
Class notes of Geotechnical Engineering course I used to teach at UET Lahore. Feel free to download the slide show.
Anyone looking to modify these files and use them for their own teaching purposes can contact me directly to get hold of editable version.
Class notes of Geotechnical Engineering course I used to teach at UET Lahore. Feel free to download the slide show.
Anyone looking to modify these files and use them for their own teaching purposes can contact me directly to get hold of editable version.
Pile foundation is important for construction of foundation where bearing capacity of soil is poor. Pile foundation is use for distribution of uneven load of superstructure.There are so many type of pile are use for construction. Here i present some of pile with suitable condition for construction and methods for construction.
Thank you.
#تواصل_تطوير
المحاضرة رقم 187
أستاذ دكتور / مدحت كمال عبدالله
عنوان المحاضرة:
تدعيم كباري باستخدام التفاعل المشترك
للمياه - جسم الكوبري
وعرض حالة عملية
Temporary Support Of Existing Bridges Using
Water-Structure Interaction
including case study
يوم الإثنين 26 ديسمبر 2022
الثامنة مساء توقيت القاهرة
التاسعة مساء توقيت مكة المكرمة
و الحضور عبر تطبيق زووم من خلال الرابط
https://us02web.zoom.us/meeting/register/tZModeusrzsoHtbqmSpzcaX1yPR0TmfeoAQl
علما ان هناك بث مباشر للمحاضرة على القنوات الخاصة بجمعية المهندسين المصريين
ونأمل أن نوفق في تقديم ما ينفع المهندس ومهمة الهندسة في عالمنا العربي
والله الموفق
للتواصل مع إدارة المبادرة عبر قناة التليجرام
https://t.me/EEAKSA
ومتابعة المبادرة والبث المباشر عبر نوافذنا المختلفة
رابط اللينكدان والمكتبة الالكترونية
https://www.linkedin.com/company/eeaksa-egyptian-engineers-association/
رابط قناة التويتر
https://twitter.com/eeaksa
رابط قناة الفيسبوك
https://www.facebook.com/EEAKSA
رابط قناة اليوتيوب
https://www.youtube.com/user/EEAchannal
رابط التسجيل العام للمحاضرات
https://forms.gle/vVmw7L187tiATRPw9
ملحوظة : توجد شهادات حضور مجانية لمن يسجل فى رابط التقيم اخر المحاضرة.
Overview of Soil Stabilization :Cement / Lime :PPTAniket Pateriya
Soil-cement is frequently used as a construction material for pipe bedding, slope protection, and road construction as a sub-base layer reinforcing and protecting the subgrade. It has good compressive and shear strength, but is brittle and has low tensile strength, so it is prone to forming cracks.
Lime can be used to treat soils to varying degrees, depending upon the objective. The least amount of treatment is used to dry and temporarily modify soils. Such treatment produces a working platform for construction or temporary roads. A greater degree of treatment supported by testing, design, and proper construction techniques--produces permanent structural stabilization of soils.
Class notes of Geotechnical Engineering course I used to teach at UET Lahore. Feel free to download the slide show.
Anyone looking to modify these files and use them for their own teaching purposes can contact me directly to get hold of editable version.
Class notes of Geotechnical Engineering course I used to teach at UET Lahore. Feel free to download the slide show.
Anyone looking to modify these files and use them for their own teaching purposes can contact me directly to get hold of editable version.
Pile foundation is important for construction of foundation where bearing capacity of soil is poor. Pile foundation is use for distribution of uneven load of superstructure.There are so many type of pile are use for construction. Here i present some of pile with suitable condition for construction and methods for construction.
Thank you.
#تواصل_تطوير
المحاضرة رقم 187
أستاذ دكتور / مدحت كمال عبدالله
عنوان المحاضرة:
تدعيم كباري باستخدام التفاعل المشترك
للمياه - جسم الكوبري
وعرض حالة عملية
Temporary Support Of Existing Bridges Using
Water-Structure Interaction
including case study
يوم الإثنين 26 ديسمبر 2022
الثامنة مساء توقيت القاهرة
التاسعة مساء توقيت مكة المكرمة
و الحضور عبر تطبيق زووم من خلال الرابط
https://us02web.zoom.us/meeting/register/tZModeusrzsoHtbqmSpzcaX1yPR0TmfeoAQl
علما ان هناك بث مباشر للمحاضرة على القنوات الخاصة بجمعية المهندسين المصريين
ونأمل أن نوفق في تقديم ما ينفع المهندس ومهمة الهندسة في عالمنا العربي
والله الموفق
للتواصل مع إدارة المبادرة عبر قناة التليجرام
https://t.me/EEAKSA
ومتابعة المبادرة والبث المباشر عبر نوافذنا المختلفة
رابط اللينكدان والمكتبة الالكترونية
https://www.linkedin.com/company/eeaksa-egyptian-engineers-association/
رابط قناة التويتر
https://twitter.com/eeaksa
رابط قناة الفيسبوك
https://www.facebook.com/EEAKSA
رابط قناة اليوتيوب
https://www.youtube.com/user/EEAchannal
رابط التسجيل العام للمحاضرات
https://forms.gle/vVmw7L187tiATRPw9
ملحوظة : توجد شهادات حضور مجانية لمن يسجل فى رابط التقيم اخر المحاضرة.
- Prepared a 2D stick model of the bridge in SAP2000 using the properties mentioned in the FHWA Bridge document
- Designed the bridge for linear and non-linear structural models to conduct analyses
- Performed different analyses on the bridge – multimode analysis, pushover analysis, time history analysis and capacity spectrum analysis
- Compared the shear force, bending moment, axial force and displacement values for each abutment and pier from all analyses and critically assessed the bridge performance
Cable Stay Bridge construction at Bardhman using LARSA and LUSAS four dimensi...Rajesh Prasad
For the construction of Cable Stayed Bridge at Bardhman, a simulation model was made using LARSA 4D and accordingly design were concluded considering all the possible situation. At the execution stage the profile/geometry control is very important. Accordingly construction stage analysis along with geometry control is being done using LUSAS software. These software are 4D and the fourth dimension is Time. The said presentation covers the LARSA, LUSAS and few pictures on execution at site along with sample of documentation.
Conceptual design and architecture of turkish communication satellite turksat...Atılay Mayadağ
Preparing a preliminary report of new communication satellite of TUBITAK. In the project, there were studied launch system standarts of spacecrafts, communicated with launch companies and prepared a cost report. Also, researched satellite safety tests and listed relevant institutions. Finally, there was chosen a suitable adaptor to assemble the satellite into the spacecraft.
• Used Computer Skills : Systems Tool Kit, Microsoft Word, Excel, PowerPoint
• Gained Social Skills : Ability to communicate, formulate and report in a clear understandable manner.
Ken Lee: 2013 Sandia National Laboratoies Wind Plant Reliability Workshop
ICDE2006, Singapore
1. Critical Levels for Monitoring of Ground
Anchor System for Deep Excavation Project
T. S. Chua, Meinhardt Infrastructure Pte Ltd
S.S. Marican, Land Transport Authority
T.W. Kok, Andrew, Meinhardt Infrastructure Pte Ltd
K. Tani, Taisei Corporation
C424 of KPE
2. Ground anchors
Permanent Temporary
Design life more than 2
years
Design life less than 2
years
FOSstruct = 2 FOSgeo = 3 FOSstrut =1.6 FOSgeo = 2.5
Non-removable:
Anchor tendons left-in
Removable:
Anchor tendons removed after use
2
4. Instrumentation and Monitoring
verification of design and activating contingency measures
• Critical levels = Alert Level (AL) and
Work Suspension level (WSL)
• WSL = Allowable level or design level
• WSL = Structural capacity or geotechnical
capacity; or its weakest links i.e. waler
• Action plans
• AL = 70% of WSL
• Exceed AL, close monitoring
• Exceed WSL, work suspension
AL WSL
70% 100%
4
Close
monitoring
Regular
Monitoring
Monitoring frequency
5. Ground anchors – Instrumentation and Monitoring
Historical practices Current practices
Numerical analysis has been used,
Pre-load less than WL
Numerical analysis routine
Pre-load = 110% WL ( BS8081 ) Pre-load = design pre-load
Instrument readings as feedback Instrument readings as Critical Level
Inconsistency acceptable
In-consistency leads to stop work
order
i.e. DL = WL, WSL = WL
Preload = 110% WL >WSL
5
6. Current issues
• What is the right pre-load?
• Should we follow BS8081:Ground Anchorages?
• How to manage the conflicts with the Code?
• Is design level a critical level?
• Should work stop if the field data hits design level?
• The best way to answer these questions is
to go through a case study, C424 of KPE…
6
10. Sequence of excavation simulated in the analysis
Excavation to 1st level Install 1st strut, excavation to 2nd level
Install 2nd strut, excavation to 3rd level Install 3rd anchor, excavation to 4th level
Install 4th anchor, excavation to 5th level Install 5th anchor, excavation to final level
10
11. Deformation of
retaining wall (Plaxis)
80.0
85.0
90.0
95.0
100.0
105.0
110.0
115.0
-10 10 30 50 70 90 110 130 150 170 190
Horizontal Displacement [mm]
ReducedLevel[m]..
Exc to belowS1
Exc to belowS2
Exc to belowGA3
Exc to belowGA4
Exc to belowGA5
Exc to FL of tunnel
Construct tunnel
backfill to below
GA5 & remove GA5
backfill to below
GA4 & remove GA4
backfill to below
GA3 & remove GA3
backfill to belowS2
& remove S2
backfill to belowS1
& remove S1
backfill to GL
Strut 1, RL112.0m
Strut 2, RL107.5m
Ground Anchor 3,
RL104.0m
Ground Anchor 4,
RL101.0m
Ground Anchor 5,
RL98.5m
Formationlevel
RL95.2m
11
16. Design of ground anchors
Structural check Geotechnical check
N = (WL X Fs) / (UTS x Rd) Lfix = (WL x FG) / (Π x D X fs)
N = required number of strands, 2,4
6... Number of unit anchor = N/2
WL = Working load of anchor, kN
Fs = factor of safety, 1.6
UTS = Ultimate tensile strength, kN
Rd = reduction factor due to bend
Lfix = required fixed length, m
WL = working load of each unit anchor, kN
FG = Safety factor for geotechnical, 2.5
D = diameter of anchor, m
fs = unit skin friction, kN/m2
Rd
16
17. All ground anchors are subjected to acceptance test
Passing criteria:
Apparent free length, Lapp = (AEδ/∆P)
Upper limit Lower limit
Lapp < Ltf +Le +0.5Ltb
or
Lapp< 1.10Ltf + Le
Whichever is larger
Lapp> 0.8Ltf +Le
17
18. Pre-load
load transferred to the anchor head immediately on completion of
stressing operation
How high to Pre-load?
• Sufficient to ensure that the anchorage resistance under
SLS conditions will be mobilised with acceptable head
displacement
• Too low – wall movement may be too large, uneven
distribution of loads
• Too high – not economical as WL will be higher, may hits
WSL
Currently with monitoring based on Critical levels,
works could be suspended
18
19. Pre-load affects behaviour of ground anchor
Type of ground anchor also affects the amount of pre-load
δ=PL/AE
Llong=24m > Lshort = 16m
19
∆δ =constant
∆P= ƒ(1/L)
U-turn system
20. Load distributions if the pre-load is too low
Pre-load to 70%
Ref. Lgth Elong
at
70%
Elong
at
100%
Addn
elong
Inc in
load
Max
load
FOS
m mm mm mm kN kN
1 24 75 107 32 44 165 1.8
2 22 69 98 29 48 169 1.7
3 20 63 89 27 52 174 1.7
4 18 56 80 24 58 180 1.6
5 16 50 71 21 65 187 1.6
Pre-load to 50%
Ref Lgth Elong
at
70%
Elong
at
100%
Addn
elong
Inc in
load
Max load FOS
m mm mm mm kN kN
1 24 54 107 55 73 160 1.9
2 22 49 98 49 79 166 1.8
3 20 45 89 45 87 174 1.7
4 18 40 80 40 97 184 1.6
5 16 36 71 36 109 196 1.5
20
21. What if the pre-load is too high?
• Design engineer assumed a certain pre-load
(70% WL), but …
• Contractor installed based on
recommendation by BS8081, (110% WL)?
• i.e. Actual pre-load higher than design pre-
load
21
24. How to overcome these problems?
• Pre-load to design pre-load
• Avoid strict interpretation of BS8081:1989
• Adopt most adverse combinations
– Max. and min. pre-load should be selected
when analyzing the temporary earth retaining
system (TERS)
• Select appropriate design parameters
– Use worst credible parameters; or moderately
conservative parameters with appropriate
safety margin
– If use most probable parameters, ensure that
there are spare capacity i.e. WSL >DL
24
Ciria C580
34. Conclusions
• ‘Critical Level’ is effective and efficient
• Pre-load affects the behaviour of ground anchor
• U-turn ground anchors
• Affected by pre-load
• Important to check internal structural capacity
• BS8081:1989, Ground Anchorages
• Strict interpretation on it’s recommendation could results in
conflict i.e. ground anchor load will breach Critical Level
• Drafted in 1989, the Code need to be re-look
• Pre-load
• Removable ground anchor system
• Case study: C424 of KPE
• Holistic approach, using conservative design parameters and
close monitoring using Critical Levels, is the key to ensure
adequacy and safety of TERS.
34