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Saturday, December 4, 2010

An executive method for embankment layers in roads and yards


    Abstract:
This is a technical note of “An executive method for embankment layers in roads and yards”.
When we proceed to execute a compacted layer, for example: soil, Base, Sub base layer in road and yards, we should know how much the soil or aggregate (as a base or sub base layer) per square meter is need for reaching to specifications of design (thickness, percentage of compaction).
Author has presented an executive method to solve of above problem in this technical note.
    Introduction:
After designing of a pavement for roads or yards, civil engineer obtains several layers of aggregates (base or sub base) and soil that they must be compacted and executed under asphalt. Each one of these layers has its own specifications included: thickness, percentage of compaction, maximum dry density, optimum moisture, atterburg limits, sandy equalent, crashing percentage and etc.
Two specifications of them are very important: thickness and     compaction percentage. In this manuscript it has been calculated: “what is the distance between unloading of two consecutive Damp Trucks a long road so that two important specifications are produced?”
     Main body Of Article describing work and results:
     The following is a list of symbols used throughout the text:
-      w%    Natural moisture of the soil
-      Dn      Natural unit weight (Free unit weight of the soil)
-      Dm     Maximum dry density
-      R %   Compaction Percentage (Design Specification)
-      Z        Thickness of layer (Design specification)
-      V2       Volume of dry compacted soil after filling
-      m2      Weight of dry compacted soil after filling
-      m1      Weight of natural soil (Free)
     - A          required Area (XY) for unloading soil of each Damp Truck
     - V1         required Volume of unloading soil on Area (XY) by each Damp Truck
In order to execute a filling layer on sub grade in the road, we start it in accordance with four stages as follows:
A)  Unloading of soil or aggregate on required area (XY) of sub grade with required volume (V1) by a Damp Truck.
B)  To distribute storage area of soil (Unloaded by Damp Truck) by a Grader so that the soil or aggregate layer reaches to thickness of design specifications.
C)  Spraying on soil by watering - Can Truck in order to reach the soil or aggregate to optimum moisture.
D)  To compact the soil or aggregate by a Roller in order to reach to compaction percentage of design specifications.
    In this technical note, the target is to obtain the required area (XY) for unloading soil of each Damp Truck or the required volume (V1) of unloading soil on area (XY) by each Damp Truck for reaching to specifications of design.

    In order to solve above problem, author has used from returning    analyze as follows:
   An element of soil (X, Y, Z) has been considered after executing of the last stage (stage D).

  Where:
V2 = Z.X.Y                                                             (1)
m2 = Dm. Z.X.Y.R                                                      (2)
m1 = m2 + (m2 * w %) = m2 (1 + w %)                       (3)
Therefore, it could be used from below formula:
V1 = m1 / Dn = Dm.Z.X.Y.R((1 + w %) / Dn                 (4)
X.Y = A = V1. Dn / Dm.Z.R((1 + w %)                        (5)
Example (1):
w = 3 %
Dm = 2.17 gr / cm3
R = 95 %
Dn = 1.53 gr / cm3
A = 10000 cm2
Z=15Cm
V1 = 2.17 * 15 * 10000 * 95 % * (1 + 3 %) / 1.53
V1 = 0.2 m3
Example (2):
w = 3 %
Dm = 2.17 gr / cm3
R = 95 %
Dn = 1.53 gr / cm3
V1 = 6 m3 = 6000,000 cm3
Z=15Cm
6000,000 = 2.17 * 15 * 95 % * (1 + 3 %) A / 1.53
A = X.Y= 288226 cm2
A # 29 m2
Conclusions:
In this technical note, author has tried to show what is the distance between two consecutive soil storage area that they have been   unloaded by Damp Trucks for reaching to design specifications in roads and yards.
It is possible only with having results of laboratory tests.
Easily, we can see that above problem is independent of optimum moisture.

Friday, November 5, 2010

The quotation of Charlie Chaplin

Here is an important quotation of Charlie Chaplin in Persian language:

لبخند بزن بدون انتظار پاسخي از دنيا، بدان روزي دنيا آنقدر شرمنده ميشود كه بجاي پاسخ لبخندت، به تمام سازهايت مي رقصد.چارلي چاپلين

I could not find the original quotation.
Can you acquire it?

I translated this quotation in English language as follows:

"Smile, without any expectation for response from the world. Be aware that someday the world will be so embarrassed that instead of answering to your smile, will dance for all of your orders."

Actually, I am not sure whether it is the quotation of Charlie Chaplin because I can not find it anywhere.

Anyways, I would like to know whose quote is. Because I enjoy it
and this quote is very important for me.

I consider below approach as my analysis:

smile = presenting of the thoughts, ideas,stories and sharing of the knowledge

There is the quotation of Immanuel Kant as follows:

“If man makes himself a worm he must not complain when he is trodden on.”

Now, let me replace glow-worm or silk-worm instead of “a worm” in above quotation.
We will have:

“If man makes himself a glow-worm he will not be trodden on during the period of the night”
“If man makes himself a silk-worm he will not be trodden on any time”

I think that above quotations are the same meanings with the first quotation (Unknown). In fact, they are two sides of a coin (extreme positive or negative).

In the meanwhile, I really enjoy from other quotations of Immanuel Kant below cited because they are completely compatible with my approach:

“Live your life as though your every act were to become a universal law.”
“May you live your life as if the maxim of your actions were to become universal law”
“Act that your principle of action might safely be made a law for the whole world”

Best Regards
Reza

Sunday, October 24, 2010

Energy saving through efficient Industrial Boiler System (part 2)

While I was researching on case study of "Energy saving through efficient Industrial Boiler System", I found a problem as follows:
Assume there is the sequence of natural numbers below cited:

a1, a2, a3, ……….an

Where: a2 = a1+ S, a3 = a2 + L, a4 = a3 + S, a5 = a4 + L ……..an = a(n-1) + (S or L)

In fact, S and L are added to natural numbers off and on.
S and L = constant members of real numbers®
We have:

an = a1 +{(n-1)/2}(S +L) If n = 2k +1
an = a1 + 0.5 {(n-2)L + nS} If n = 2k

Do you know any easy way to calculate below series?
SUM (an) from n = 1 to n = i and “i” is a member of natural numbers

Is there any real number for: limit Sum (an) if “n” tends to infinity?

I would like to inform you that my problem has been solved by Mr. Nico Potyka on below link:

https://www.xing.com/net/mathe/general-interest-remarks-and-links-5223/energy-saving-through-efficient-industrial-boiler-system-33117616/

The answer is as follows:

Let's consider the cases s1, and si for even and uneven i.

1. s1 = a1

2. 1 < i = 2k+1. Let's decompose the sum in separate parts for a1, S and L. Then we obtain:

coefficients of a1:
i

coefficients of S:
(i-1) + (i-3) + ... + 2
= (1 + 2 + ... + (i-1)/2) * 2
= ((i-1) / 2 * (i+1) / 2) / 2 * 2
= (i^2-1)/4

coefficients of L:
(i-2) + (i-4) + ... + 1
= 1 + 3 + ... + (i-2)
= ((i-1)/2)^2
=(i-1)^2/4

So in this case we obtain si = a1*i + S * (i^2 - 1) / 4 + L * (i-1)^2 / 4

3. 1 < i = 2k.

coefficients of a1:
i

coefficients of S:
(i-1) + (i-3) + ... + 1
= 1 + 3 + ... i-1
= (i/2)^2
= i^2 / 4

coefficients of L:
(i-2) + (i-4) + ... + 2
= (2 + 4 + ... + i-2)
= 2 * (1 + 2 + ... (i-2)/2))
= 2*((i-2)/2)*i/2)/2
= (i^2 - 2i)/4

So we obtain si = a1*i + S * i^2 / 4 + L * (i^2 - 2i) / 4



Better check the result ;)



PS. A general form for i in N is:

si = a1*i + (as*S +al*L) / 4
where as := i^2 - (i mod 2)
and al := (i-1)^2 - ((i+1) mod 2)

So much to thank him for solving of my problem.

PS: I consider this quotation “Xenophanes said: The gods did not reveal all things to men at the start; but, as time goes on, by searching, they discover more and more” for below link (camel - stationary traveller):
http://www.youtube.com/watch?v=MKBwku-PsPY&feature=relat...

Best Regards
Gholamreza Soleimani

Monday, October 18, 2010

Energy saving through efficient Industrial Boiler System








1. Introduction

This report is previous paper continuation of “Saving Techniques: optimization in Boiling water consumption” in which it is willing to debate the role of energy saving in industrial sector such as steam generators. The result of previous paper shows us positive influence of energy saving on boiling water consumption in the public sector while we will not have the same outcome in industrial Boiler system. Why? According to IEO 2010 Reference case, total energy consumption in the world industries will increase an average of 1.3 percent per year from 2007 to 2035. In addition, worldwide industrial energy consumption is equal to 184 quadrillion Btu in 2007 and 262 quadrillion Btu in 2035 whereas total world energy consumption is equal 495 quadrillion Btu in 2007 and 739 quadrillion Btu in 2035. Consequently, industrial energy consumption in the world is approximately 35 to 37 percent of total sum world energy consumption. Besides, only 30 percent of total energy consumption for industrial productions (outputs) is used by the steam energy. Therefore, the influence of energy saving by using of steam on the growth of total energy consumption in the world is negligible.
Why should we increase the efficiency of steam generators?
It is due to competition among industrial companies in the world.
IEO2010 stated, there are five industries that they consume the half of total energy in industrial sector as follows:

-Chemicals 22%
-Iron and steel 15%
-Non-metallic minerals 6%
-Pulp and paper 4%
-Nonferrous metals 3%

Among industries, Pulp and paper manufacturing and Petroleum refining and chemical manufacturing respectively use huge amount of steam as a percentage of total energy consumption as follows:

Industry Total energy consumption by steam
(%)
Pulp and paper manufacturing 84

Petroleum refining 51

Chemical manufacturing 47


As we can see, if pulp and paper manufacturers companies save the energy through efficient industrial Boiler, they can manage the standard cost of their produced goods and finally it will be affected on the lifestyle of their productions. This case is the same for petroleum refining and chemical manufacturers.

How can we increase the efficiency of industrial Boilers?

2.0 Literature Review

As I mentioned beforehand, there are so many common approach about efficiency of Boilers as follows:
Kilicaslan and Ozdermir (2005) stated that Boiler efficiency is ability rate for producing steam from a type of fuel.
Boilers are the equipments which exchange chemical energy to thermal energy(energy in steam) where we have:
Energy in fuel (coal, oil or gas) = Energy in steam + Energy in Heat losses
In fact, for enhancement of Boiler efficiency, we should decrease the losses of Heat in Boilers.It means the conservation of the energy.



What are depressor ways of Heat losses?

It is clear, the biggest energy loss in Boilers are related to exit of the stack gas from the chimney in which the volume and the temperature of the stack gas are determinant factors on heat losses. As Kaya et al (2007) mentioned that incomplete combustion, excess air, water vapor in flue gas, flue gas temperature, fuel type, burners, boiler load, heat loss from boiler surface and the heater surface dirtiness are actual effective factors on Heat losses. And so in a case study conducted by Kaya and Eyidogan (2010), they found that leakage air losses in Rotary Type Air Heater (RTAH) are the most important factor on Boiler efficiency because it is caused an increase on excess air and finally prevents to reach Boiler to full operation.
American Boiler Manufactures Association (ABMA) also refers to the ASME power Test
Code, PTC4 or BTS-2000 to calculate Boiler efficiency that it is included the stack gas, radiation and convection losses. According to ABMA, the principal factors, which are effectively on Boiler efficiency, could be considered as follows:

1) The temperature of Flue gas
2) Heat losses because of the stack
3) The pressure of the steam (High-Medium- low pressure steam)
4) The losses because of Radiation and Convection
5) Excess air
6) The temperature of ambient air
7) Type of fuel

Energy Efficiency Handbook (2007) published by CIBO (Council of Industrial Boiler Owners), introduced several useful strategies for decreasing Heat losses of the stack gas as follows:

1) Reduction of excess air:
When excess air increases, Nitrogen of air rapidly absorb thermal energy and we will have heat loss.




2) The heat transfer surfaces should be clean because these dirty surfaces work just like to an insulation system and absorb the heat so that we will have heat loss.

3) Using of outlet flue gas as combustion air by recovery equipments such as APH (Air Pre-Heater), Economizer in which they work the similar to heat exchangers.

4) Combustible Heat losses:
Because of unburned fuel in ash, heat losses will increase. In fact, the main reason for unburned fuel is not to be enough combustion air. Another reason is the type of fuel.

5) Controlling of air leakage:
It can be done by changing of manufacturing in Rotary Air Pre-Heater (as a new idea) or to replace a new one because of erosion.

6) Radiation Heat:

Thermal exchange between Boiler body and environment is another heat loss that it could be solved by a proper insulation of Boiler.
As we can see, all of above references reflect the influence of the volume and the temperature of Flue gas (stack gas) as a main factor on Heat losses and Boiler efficiency. In fact, if we decrease the temperature of outlet fumes from Boilers, we will have a reduction of excess air accompanied by controlling of air leakage and finally operating of Boiler in full load.
There is the equipment in steam generator systems that it is named Regenerative Air Pre-Heater. It is made by several plates in which flows of inlet and outlet fumes heat the plates and flows of cool air absorb the heat of plates. In the result, the plates of Air Pre-Heater transfer the heat of fumes to cool air. We have two types of this tool:
1) Rotating-Plate Regenerative Air Pre-Heater
2) Stationary-Plate Regenerative Air Pre-Heater



RAPH has a rotor which rotates the plates with slow speed (about 3-5 rpm) while the plates of SAPR are fixed. Each one has the advantages and disadvantages.


In here, I would not like to illustrate the technology of Regenerative Air Pre-Heater more but it is better we zoom the influence of this technology on energy saving in Boilers.

3.0 Research Methodology

All of technical information as secondary data has been obtained by searching in Internet (Google website) and case study has been downloaded from UTM library zone.

4.0 Data Analysis and Discussion

I have brought a case study about the ways of enhancing efficiency through steam generators at high pressure operating here that I will explain the reason of it in conclusion.
Kaya and Eyidogan (2010) conducted a experimental study on boiler which was operating at 420 Bars and 440 ° C temperature whit a natural fuel gas in which the nominal capacity of Boiler was 33.33 kg/s.




They measured the volume, velocity, pressure and temperature of flue gas in outlet and chimney accompanied by mass balances and exergy analysis. According to their measurements, Boiler efficiency was obtained around 88.28% and exergetic efficiency was equal to 36.7%. They found the huge losses of efficiency which was due to air leakage in Rotating-Plate Regenerative Air Pre-Heater so that it increased not only the temperature of flue gas in stock (chimney) but also decrease the capacity of Boiler in full operating by increasing of excess air and incomplete combustion.
According to their data, total energy saving potential was calculated as follows:
Type of energy saving Energy saving potential
(%)

Avoiding excess
leakage air losses 31.14

Reduction
of excess air 17.81

Operating
the boiler
at full load 36.56


Reduction of
flue gas
temperature 14.49



Total 100

Total Energy Saving Potential

Why have we leakage air losses? Because the erosion will occur on the plates in the period of time in connection with the fumes flows. If we decrease leakage air, we will increase the operating of Boiler in full load so. How can we scale down leakage air? By using of new technology, modernization and change in manufacturing of Rotating-Plate Regenerative Air Pre-Heater.
Regarding to total energy saving potential, they calculated the finance of new manufacturing included in investment costs and payback period as follows:



Finance of new manufacturing (RAPH)

-Manufacturing Cost of new model RTA-Heater $600,000
-Annual net profit of Energy saving:
- By avoiding excess leakage air losses $221,625
- By operating the boiler at full load $260,215
-Total profit $481, 840
-Payback period ($600,000/481,840) 1.245 years 15 months
In this case study, the influence of leakage air plus full operating of Boiler has been considered as total sum of energy saving. In my opinion, if we decrease the volume and temperature of flue gas, we will cover every three another items such as saving energy by reducing of leakage air and excess air that finally the result will be the operating of Boiler in the full load condition. In fact, we need new ideas for next generation of Regenerative Air Pre-Heater which could be adopted from the parameters as follows:
- Increase of sum total area of each plate
-Number of plates
-rpm of motor drive
-Material of plates
As we can see, the function of energy saving in Boilers is depended on four variables and we should solve this problem by consideration of maximum energy saving and optimum cost of manufacturing.

5.0 Conclusion

This paper shows us how the business such as marketing in the field of competition can manage a technology as the core to stay in stocks and continue the lifestyle of production. And so, it represents us how an idea can be as a base of R &D and innovation and complete the cycle of process development for the production. Therefore, the new ideas are very important for industry.
Why do I use from this case study?



We will have the big challenge with extraction of crude oil throughout the world in the near future. In the matter of fact, one of the best ways will be the injection of high pressure steam to extract crude oil from wells in which we will have to decrease the cost of high pressure steam by saving of energy. This will be the important strategy for firms in the field of oil & gas.
In the result, apparently the influence energy saving by using of steam on the growth of total energy consumption in the world is negligible but if we measure the performance by a Balance Scorecard method as a research study, we will perceive that the conclusion is vice verse. In fact, there is the high influence of energy saving on total energy consumption in the world by using of steam in industry.

6.0 References

- American Boiler Manufacturers Association. (2008, May). Determining & Testing Boiler Efficiency for Commercial/Institutional Packaged Boilers. Retrieved September 4, 2010, from http://www.abma.com/Commercial_Boiler_Efficiency.Determine.Test.FINAL_POSTED_TO_WEBSITE.pdf/.
- Gietz, M., Schule, V., & Faller, B. (2009). Method for Optimised Operation of an Air PreHeater and Air Preheater. United States Patent Application Publication,US 2009/0095440 A1.
- Kaya, D., & Eyidogan, M. (2010). Energy Conservation Opportunities in an Industrial Boiler System. Journal of Energy Engineering, 136, 18-25.
- U.S. Department of Energy. (2003). How To Calculate The True Cost of Steam.
DOE/GO-102003-1736. Washington, DC: U.S. Industrial Technologies Program.

- US. Department of Energy. (2006). Best Practices: Steam. DOE/GO-102006-2275. Washington, DC: Energy Efficiency and Renewable Energy.

-US. Department of Energy. (2004). Improving Steam System Performance. DOE/GO-102004-1868. Washington, DC: Energy Efficiency and Renewable Energy.

-US. Department of Energy. (2002). Steam System Opportunity Assessment for the Pulp and Paper. DOE/GO-102002-1639. Washington, DC: Energy Efficiency and Renewable Energy.

-U.S. Energy Information Administration. (2010). International Energy Outlook 2010. DOE/EIA-0484(2010). Washington, DC: Office of Integrated Analysis and Forecasting.

- ZEITZ, R. A. (2007). ENERGY EFFICIENCY HANDBOOK. COUNCIL OF INDUSTRIAL BOILER OWNERS (CIBO). Retrieved September 4, 2010, from http://www.cibo.org/pubs/steamhandbook.pdf/.

Thursday, October 7, 2010

ACI - 211 At Our Homes

Abstract: 

 This Technical Note has presented an executive method for concrete placing in small building sites.
Since there is not a mechanized and automatic systems for concrete placing ( Cast - in - place ) in small building sites (included : Batching plant , Batch mixer , Truck mixer , … ) , a contractor utilizes from drum mixer or handling mixer by volume batching method .
In this Technical Note, author has tried to show changing of weight batching to volume batching of concrete materials (cement, water, aggregates) so that weight batching has already obtained by using of ACI-211 (Mix Design).
Therefore, ACI-211 can be used even at our homes.





Introduction: 

In order to execute concrete placing (cast-in-place) at the sites, it needs to be obtained a mix design of concrete.
A mix design of concrete (in accordance with ACI-211) introduces us only the weight batching of cement, water, aggregates.
We can use from weight batching, if we have had a batching plant, batch mixer, truck mixer…
In fact, if we have had a mechanized and automatic system for concrete placing that it is used only in big and large sites.
But we have to use volume batching instead of weight batching in small sites.
In this paper, author has presented a method for changing of weight batching to volume batching.

Main Body of Article Describing work and Results:

In here, we proceed step by step for changing of weight batching to volume batching:

1) We should get the results of simple tests on aggregates as follows:

- Sieve analysis of coarse and fine aggregates
- Free unit weight of coarse aggregate
- Free unit weight of fine aggregate
- Free unit weight cement

2) According to above tests results and tables of ACI-211, we can estimate weight batching of concrete materials.

3) We assume weights batching of concrete materials per one cubic meter of the concrete in according with point (2) are as follows:
- ma Weight of coarse aggregate / 1 m3 concrete
- ms Weight of fine aggregate / 1 m3 concrete
-mc Weight of cement / 1 m3 concrete
- mw Weight of water / 1 m3 concrete

4) So, we should get the volume of a batch that it is available for us and total volume of Drum Mixer should be recognized that it depends on to type of Drum Mixer (It is Standard)
- v1 Volume of an available batch
- v2 Total Volume of Drum mixer (Volume capacity of Drum mixer)

5) According to point (1), we have:
- da Free Unit weight of coarse aggregate

- ds Free Unit weight of fine aggregate
- dc Free Unit weight of Cement
- dw=1000 Kg / m3 Free Unit weight of Water

6) In this step, we can get the volume of each one of the concrete materials for one cubic meter of the concrete:

-va =ma / da The volume of coarse aggregate / 1 m3 concrete
-vs =ms / ds The volume of fine aggregate / 1 m3 concrete
-vc =mc / dc The volume of Cement / 1 m3 concrete
-vw =mw / dw The volume of Water / 1 m3 concrete
-vT = va + vs + vc + vw Sum of concrete materials volumes

7) According to Volume of Drum Mixer, we should calculate the volume of concrete materials for one Drum Mixer batch:

- VIa = v2.va / vT The volume of coarse aggregate / 1 unit Drum Mixer batch
-VIs = v2.vs / vT The volume of fine aggregate / 1 unit Drum Mixer batch
-VIc = v2.vc / vT The volume of Cement / 1 unit Drum Mixer batch
-VIw = v2.vw / vT The volume of Water / 1 unit Drum Mixer batch

8) We should get number of batches:
N = v2 / v1 Number of total batches

9) Now, we can get number of batches for each material of the concrete with using of below formula:

ni = N.VIi / v2
VIi = v2.vi / vT
ni = N.vi/ vT
vT = SUM vi = va + vs + vc + vw
ni = N.vi/ SUM vi
vi = mi / di
ni = N. mi / di SUM mi / di

Where:

- i Each one of the concrete materials (aggregate, cement, water)
- n Number of batches for each material of the concrete
- N Number of total batches
- mi Weight of each one of the concrete material / 1 m3 concrete (According to ACI-211 Tables)
- di Free Unit weight of each one of concrete material

Example:

According to ACI-211 Tables, we have obtained amount of materials per one cubic meter of the concrete as follows:
- ma = 1040 kg
- ms = 830 kg
-mc = 350 kg
- mw = 190 kg

And so, free unit weight of above materials is below cited:

-da = 1470 kg / m3
- ds = 1530 kg / m3
- dc = 1200 kg / m3
- dw=1000 Kg / m3

The volume of Drum Mixer and the Volume of the batch sample are:

- v1= 0.2 * 0.2 * 0.2 = 0.008 m3
- v2 = 0.2 m3

Therefore, we have:

N = v2 / v1 , N = 25 Number of Total batches

Now, we can calculate number of batches for each materials of the concrete. For instance, batches number of coarse aggregate is calculated as follows:


ni = N. mi / di SUM mi / di

na = 25 * 1040 / 1470 (1040/1470 + 830/ 1530 + 350 / 1200+ 190/1000) = 10.2
Conclusion:

 According to previous mentioned matters, we can execute concrete placing by using of ACI-211 or another standard and volume batching method in small sites where there is not any mechanized or automatic system.
Therefore, we can speak about optimum slump, W/C, quality of concrete even in small building sites.
Small building sites could be meant even when we are using of concrete in our homes.
But we should notice, for producing the concrete with high quality, all of aggregates, cement and water should be tested in laboratory before using of them.

Executive methods for solving of the problems (part 3-conclusion)

Conclusion:

Regarding to the points and examples mentioned in this manuscript , there are many methods for solving of the problems.


One of the best ways to solve the problems is to go along step by step as follows:

Step1) To find out exact definition of the problem.

Step2) To make a sentence that is exactly included all of the problem basic concepts (To summarize exact definition of the problem by a sentence).

Step3) To search the guiding channels of knowledge for each word or perfect sentence just like to use of the search engines.

Step4) To select of collected knowledge so that we find out the logical relation among them.

Step5) To find out assumptions, dependent and independent variables (unknowns) by using of Step (4).

Step6) To establish the differential equations by using of Step (5) and the points A to T mentioned in this paper.

Step7) To solve the differential equations by deleting of many variables (unknowns) so that we must observe balance of the Time and Energy (Cost).

Concerning to above steps, we can use of “Equilibrium Theory” for solving of the problems in the world. Maybe, one day we will be able to find out an opportunity of the Reference Frame with datum coordinates by using of Equilibrium Theory and Returning Analysis. We as well as know that all of Equilibrium systems are the unstable and we must spend the energy for increasing of Equilibrium stability time. One of the most important sources to secure of the energy is to use of Educational systems.
In fact, the key for solving of the problems in the world is basic and essential changes in Educational systems so that the students in the all of educational fields included: Natural science, Medicine, Art groups, Social science and etc should study Basic Physics, General Mathematics and finally Equilibrium Theory.

Gholamreza Soleimani

Wednesday, 3 May 2007

Executive methods for solving of the problems (part 2-examples of Geotechnical Engineering)


Following to article of "Executive methods for solving of the problems (part 1)" posted on link:
http://www.emfps.org/2010/10/executive-methods-for-solving-of.html, the purpose of this article is to present the examples to solve the problems in the field of Geotechnical engineering in which these examples are real projects and my real experiences when I was working as a Geotechnical engineering consultant. 

Example (1):

It was March 2002, one of my clients sent me a soil reports to examine that it had been caused a conflict between my client and their consulting engineers company who had presented the allowable bearing capacity equal to 20-30 ton for single precast concrete piles in their soil reports as follows:

       Dimension of precast piles


L=25-30 m Length of precast piles

Qa=20-30 ton Allowable bearing capacity of precast piles

When I studied Geotechnical reports, I understood that they was taking two great mistakes because the results of Triaxial(U.U) and Shear box(C.D) tests were too much more less than the results of S.P.T tests from depth 18m to final boring (35m) :


1) It sound that they had done Triaxial and Shear box tests on undisturbed samples collected from High Over Consolidation clay (H.O.C clay layers) and it had been caused that undisturbed samples were changed to disturbed samples in Laboratory(the allowable bearing capacity had been calculated in accordance with laboratory tests).

2) It sound that they had taken into the soil characteristics uniformly until depth of 25m.

The results of my views are as follows:

(Regarding to incompatibility between the results of field and laboratory, I have only used of the results of field (S.P.T) except soil classification)

-From depth of 0.00 to 18m:

(G.W.T: Average 1.5m from 0.00 level of bore holes)
1) Soil classification: CL, ML

The soil layers were U.C to N.C (under to normal consolidation) and according to Table 3-5 of J.E Bowles 1996, we have;













-From Depth of 18m to 23m:

1) Soil classification: CL, ML










8) Consistency: Very Stiff
The soil layers were O.C (Over Consolidation).


-From Depth of 23 to 30 m:

1) Soil Classification: CL, ML (Cemented)










The soil layers were H.O.C (High Over Consolidation).

According to above mentioned, allowable bearing capacity of pre-cast concrete piles (Driving) were calculated in accordance with ALPHA-method of M.J.Tomlinson by me as follows:
(In here, the executed dimension has been only calculated that it is 40* 40 cm)










Where:











Total settlement (Elastic) had been estimated in accordance with Braja.M.Das by me below cited:

S1 = 0.54 cm Elastic settlement of pile body (concrete)

S2 = 0.32 cm Elastic settlement of pile point soil

S3 = 0.24 cm Elastic settlement of pile sides soil

S = S1+ S2 + S3, S = 1.1 cm

Where:











The consolidation settlement had been calculated for piles group and it was negligible just like to elastic settlement.
Therefore, the settlement was not controller and allowable bearing capacity was announced 89 Ton.

This example is included points : A,C,D,F,H,I.

My design was caused a saving money about 3.5 million Euro and so saving time for my client that it was more important than saving money.


Example (2):

Regarding to example(1), I prepared a operating instruction manual accompanied by executive details for construction(pre-fabrication) and transport of pre-cast piles and so method of driving pile ramming that summary of it is as follows:

-Anticipation of amount of piles penetration during ramming at the site in accordance with static bearing capacity obtained in example (1) and modified ENR formula (Dynamic pile formula) for controlling of the results of static bearing capacity (Returning Analyze), and so a Table had been made for this case by me.

-To determine allowable bearing capacity by using of dynamic pile formula (modified ENR formula) as follows:

-Type of diesel piling hammer: K35
-Set final (Refusal): 6 blows/in
-Pile length (L): 23m
-Safety factor: 6
-Efficiency of hammer (E): 80%
-C =0.1 , n = 0.45

Where:










Therefore, it was compatible with the result of example (1) and so a Table had been made for this section.

-To determine produced stress in piles during ramming:

Set final (Refusal): 6 blows/in










-To determine minimum length for jointed pre-cast concrete piles:

According to Swedish Code:








Above ratio is for diesel piling hammer.
Therefore, due to diesel piling hammer (K35), minimum length of piles must be 10m.

-The methods for lifting, picking up and transferring of piles:

According to Fig.7.1, Fig.7.2 and Table 7.1 from book of Pile Design and Construction Practice by M.J.Tomlinson (1981) and regarding to length and main reinforcement of pre-cast piles, we can design the methods of lifting piles.

-Maximum cracking on surface of concrete of piles:

Because of ramming, it is possible to be created some crack on surface of concrete.
According to England standard (CP110), maximum opening is 0.3mm for embedded concrete and for expose concrete; it must not be increased from 0.004 times thickness of cover on main reinforcement.

-To control of negative skin friction by using of bitumen coating on piles:

After pile ramming, if backfilling with the thickness equal to 1 m is executed on natural soil and the sides of piles, in accordance with Bowles (1996) we have:



















Therefore, we have:

L1=16.2 m Distance to the neutral point

Qn = 39 Ton Total force of negative skin friction

In accordance with above mentioned, executive instructions for coating are as follows:

a) Mix bitumen RC-30 as pre-coating (amount of 0.1-0.5 lit/m2).
b) Bitumen 60/70 or 30/50 as final coating with thickness of 10mm plus or minus of 2mm.
c) Maximum length of coating: 16.2 m.

-To prepare ID-card for each pile

-Quality control procedure of concrete for reaching to the design compressive strength of concrete equal to 550 kg/cm2 that it must be used of Micro-silica with super plasticizer additive.

-Quality control of water, cement and aggregates

-Design of pile point:

If dimension of pile point is 10*10 cm, the angle between side plane of pile and vertical plane must be about 30 degree.
If dimension of pile point is 15*15 or more than that, above angle is calculated from below formula:



d = diameter of pile (cm)

This example is included points: B, C, D, F, H, M, Q.



Example (3):

Regarding to example 1 and 2, I had been informed by site manager that some pre-cast piles had been driven no more than depth of 18m. It meant that they had reached to a very hard layer. I checked it out and I found out that the distance between this piles were less than 3m.
Unfortunately, before starting of geotechnical activities, it had not been done any appropriate Geology, Hydrogeology and Geophysics investigations at the site.

Therefore, I ordered to do Seismic Refraction Survey (one of Geophysics methods) and provide Geology records.
We know, in accordance with velocity of “P” waves, we can calculate thickness, hardness and compaction (density) of soil layers as follows:






According to Geology records and results of Seismic Refraction Survey, it was discovered that there was a Dendroidal shape of High Over Consolidation clay (clay stone) after depth of 16-17m. In fact, location of project was on a Delta (connection of river to sea).

Note: Sometimes alluviums or loose fill (made-up gravel) have been laid unconformity on geology formations included: out crops, folded rock stratums that their geomorphology have been shown in shape of up and down (roughness).
Therefore the logs of two bore holes, which have very low distance between them, are not compatible together. It is possible, one of them encounter to rock layer in depth of 1m but another bore hole come in contact with this rock layer in depth of 10m.
One of the best ways to specify this problem is to use of German Light S.P.T equipment (DIN 4094). The specifications of this equipment are as follows:

D =22 mm Rod diameter
D*=35.6 mm Point diameter
a =60 degree Point angle
W = 10 kg Hammer mass
H = 50 cm Free falling height
A = 10 cm2 Point area

We can even change number of blows to ASTM-D1586 in accordance with energy equilibrium’s principle.

This example is included points: B, C, D, E, F, G, H, L, M, N, R, S.


Example (4):

Referring to examples (1), (2) and (3), load test of pre-cast piles (compression tests) was done by my client for controlling of my design.
Regarding to my client’s records, three pre-cast piles had been tested in accordance with ASTM-D 1143-81.The results of compressive loading tests on pre-cast piles adopted from load-settlement curves were as follows:

-Pile number: P059

L = 21 m (because of the problem mentioned in example (3), B = 40*40cm

Q = 280 Ton Maximum load

dz = 21 mm Maximum vertical displacement

For vertical displacement = 11mm, we have: Compressive load = 175 Ton







Pile number: P126-

L = 24 m, B = 40*40 cm

Q = 340 Ton Maximum load

dz = 19 mm Maximum vertical displacement

For vertical displacement = 11mm, we have: Compressive load = 195 Ton






-Pile number: TP11

This pile was a tentative pile not to operate and it had proved that the length of piles must be more than 21m.

L = 18 m, B = 40*40 cm

Q = 140 Ton Maximum load

dz > 55 mm Maximum vertical displacement

In accordance with Load- Vertical displacement curve, we have:








Therefore, the design of pre-cast piles was approved by my client.

On the other hand, there was an important problem in Destacking house (a ware house for storing of galvanized sheets). The problem was “Effect of adjacent surcharge loading on lateral displacement of pre-cast concrete piles” because galvanized sheets, which were stored on finish floor of ware house ( Destacking house), were to maximum distance of 0.25 m from pre-cast piles executed under columns of Destacking house(pile caps) and if lateral displacement of pre-cast piles was increased more than allowable limit, overhead traveling crane was stopped.

Here is loading specifications of galvanized sheets:

B*L = 4.5* 12.2 m, Dimension of galvanized sheets

T = 10 mm, Thickness of galvanized sheets

H = 3.5 m, Height of storing (on each other)

P = 7800 kg/cm3, Specific gravity of galvanized sheets

Therefore, loading of galvanized sheets was just like to loading of a rectangular footing that it was equal to:




The summary of my research method in accordance with lay out of galvanized sheets storing is as follows:

-Analysis of loading adjacent pre-cast piles in accordance with Boussinesq equation (JE.Bowles 1996)

-The calculation of bending moment and lateral displacement of pre-cast piles in accordance with equations and curves presented by Davisson and Gill (1963) as follows:






According to above mentioned, it obtained maximum bending moment and lateral displacement below cited:





So, I ordered to do a modeling test of loading adjacent pre-cast pile at the site as follows:

-A pre-cast pile was rammed at the site (L = 15 m, B = 40*40 cm).

-A plate load test (just like to ASTM-D 3966) was done by several rigid plates (maximum dimension of 100*100 cm) and maximum load of 50 Ton with distance equal to 20 cm from pre-cast pile( the distance between center to center of pre-cast pile and rigid plate was 90 cm).

-Three of gauges were installed for measurement of lateral displacement of pre-cast pile during the plate load test.

The results of modeling test showed a maximum lateral displacement equal to 4.5 mm.

The conclusion of research:

-All of analysis and calculations were approximately confirmed by modeling test.

-I offered to control the lateral displacement of pre-cast piles the points as follows:

1) To increase of inertia moment by executing of additional piles.
2) To decrease of at-rest lateral stress ratio(Ko) by using of lean concrete between galvanized sheets and pre-cast piles until critical depth.
3) To use of reinforced concrete tie beam between two against columns.

This example is included the points: A, B, C, D, F, G, H, I, K.


Example (5):

I have mentioned this example because it is included the point: “J” that is one of the most important points for solving of the problem.
Regarding to examples: 1, 2, 3 and 4, there was a great problem in production house because there must be installed a press machinery in depth of (-6 m) while Ground Water Table was about depth of (-1.5 m).
I offered to use sheet piling for the excavation. Before designing of sheet piles, I must control below points:

- “Heaving” because of instability the clay layers of trench floor. In accordance with Bjerrum and Eide(1965), we can calculate ‘Heaving’ as follows:






- “Piping” because of difference between hydraulic gradient outside and inside of excavation (arising of pumping dry) as follows:












h: The difference of water head between outside and inside of excavation

- “Ground loss” because of sides ground settlement arising of movement of sheet piles.

- Over turning of sheet piles in accordance with diagram of design stress envelope (Peck1969).We usually use of Struts and Wales for controlling of over turning.
In here, the important point was not designing of sheet piles but it was the omission of Struts and Wales by me because I ordered to use of the beams for connection of pre-cast piles executed (previously) around of sheet piles (out side of excavation location) to sheet piles.
This example as well as shows the point: “J”.

According to this example, we can see that a soft ware is not enough for designing alone.

Example (6):

This example is also compatible with point “J”.
I received a request of another client that it was the excavation of urban zone till depth of 15 m. After visiting of the site, I offered to execute of the temporary supporting structure by using of Drilled-in-Place piles.

Note: “Always there are too much problems for excavations in loose soils, especially if the depth of them is very high (deep). In addition to soils problems, two important factors are also the controller of stabilization methods that they are Time and Cost (Energy).
One of the simplest methods for excavation is to use of Drilled-in-Place piles as the retaining wall but the most important thing to analyze and design them is to stable against over-turning because Drilled-in-place piles could not be designed and executed for excavations with high height of the walls without Struts and Wales.
In this example, the methods have been proposed for deep excavations by using of Drilled-in-Place piles and acquiring of a wedge failure is shown based on both theoretical considerations and observations of model footing (Jumikis(1962), Ko and Davidson (1973)) and finite elements model for securing passive pressure of soils as resisting force against over turning so that Drilled-in-Place piles can be executed the stepped shape or two row piles that one is supporting the piles near to the wall.
Before an excavation is started to be executed, it must be studied if a vertical wall into soil will be the stable without a supporting structure and what is amount of safety factor or critical height.
In first step, mechanical parameters of soil should be obtained in accordance with Geotechnical investigation and so we can use of returning analysis.
In second step, loading analysis should be considered regarding to surcharges loads and soil specifications.
In third step, we should design a retaining wall as supporting structure, if a vertical wall without a retaining wall is not the stable.”



Specifications of the project:


6-1) In the southern part of the project ground:

Under footing of a building (two floor) had been excavated to depth of 12 m without any supporting structure and it showed a section of cemented sandy gravel layers (Hezar Dareh conglomerate of geology formations).
Regarding to the stabilization time (about 1year) of excavation, I estimated minimum the parameters of soil layers by using of Retaining Analysis as follows:

-Taylor Method (1937):


















Therefore, minimum selected characteristics of Conglomerate layer are:









6-2) In the western part of the project ground:
Concerning to Geotechnical investigations included: Test pits, Standard Penetration Tests and Remolded Shear Box Tests, soil characteristics were selected as follows:

- From depth of 0.00 to depth of 5 m (very loose sandy gravel with clay):








- After depth of 5 m:

There was Conglomerate layer just like to (6-1) as follows:








Therefore, the problem was point (6-2). In the western part of the project ground, I offered to use of Drilled-in-Place concrete piles as the temporary supporting structure.

Step1) Loading Analysis:

-There was a traffic load as the surcharge load with distance at least 70 cm from wall edge, that I considered it as a model of continuous foundation as follows:

B = 30 cm, Width of continuous foundation
Q = 5.6 kg/cm2, Loading by continuous foundation

According to Bowles (1996) and Boussinesq equation, the load diagram was obtained just like to a parabolic curve that total sum of load and load resultant are as follows:









- Lateral pressure of soil:


















Step 2) Geotechnical design of Drilled-in-Place piles:



It was included the points as follows:

- Length of piles (L)
- Diameter of piles (d)
- Numbers of total piles (N)
- Distance of center to center the piles from each other (r)
- Length of clamping (fixity) of piles into cemented sandy gravel layer (h)

For Geotechnical design (above points), below parameters must be controlled:

- Stabilization controlling against over-turning.
- Stabilization controlling against sliding forward.
- Stabilization controlling for allowable bearing capacity of foundation.
Usually, the important problem is over-turning and the other cases are ok.) )

-Assumptions:

H = 500 cm, Excavation from depth of 0.00 to 500cm
h = 250 cm (0.5H)
L = H + h = 750 cm
d = 80 cm
N = 7 In accordance with length of excavation wall
r = 125 cm In accordance with length of excavation wall

- Calculations for controlling of over-turning:


















Therefore, we have:
















Important Note:

It is possible only using of passive pressure (Pp), if it was executed a stair with width equal to 2.5 m (from Conglomerate layer) in front of piles for securing of passive pressure. Width of stair could be calculated in accordance with model footing of Jumikis(1962), Ko and Davidson(1973) accompanied by using of finite element model. Of course, it can be a research work at the university.



So, we can obtain characteristics of soil by Returning Analysis where we can use of a Grab Bucket Crane at the site so that the excavation is done in center of the project ground (limited section) until appropriate depth by a Grab Bucket Crane for reaching to a critical safety factor.

Therefore, this example as well as shows the points: “J” and “Q”.


Example (7):

This example is compatible with the point: “O”.
Concerning to example (6), I was persuaded to do structural design of Drilled-in-Place concrete piles by my client because of lack of time (I present the Geotechnical design for the projects because I have only studied BSc degree in the field of Geology at the university). For structural design of concrete piles, I had to read chapters: 1, 2, 4, 5, 6 and 10 from Mechanic of Materials book (by Popov.EP) and ACI-318.

Here is my design method:

Drilled-in-Place concrete piles had been considered as Cantilever beam.
According to free body diagram:







Regarding to bending moment and shear diagrams, maximum main longitudinal reinforcement must be executed from bottom of piles (on ground) to the height of
4.5 m and according to ACI-318, maximum bars are 6% of the piles cross section
as follows:











Assumptions:







For acquisition the equivalent section of concrete and bars and calculating the moment of inertia, I considered total cross section of reinforcements just equal to thin-wall steel pipe as follows:

t: Thickness of thin-wall steel pipe (cm)

















Therefore, all of assumptions were ok.
Since bending moment was the controller (not shearing force), this design was approved to execute by me.

This example as well as present the points: “O” and “M”.

Example (8):

This example is a general idea or a hypothesis for highlighting of the point: “N”.
Maybe, one of the ways to improve saturated clay soils (N.C) will be to prevent their drainage in the future.















Example (9):

I have brought this example because it is compatible with the point: “P”

In one of the earth dam projects, we had to inject Red-colored water into the joints and cracks of Rocks under dam foundation for finding out direction (orientation) and distribution of them.
Red-colored water had been appeared on the ground surface until radius of 30 km far away from the location of Dam. It as well as showed connection among the joints and cracks.