La desviación permitida de los pilotes de la verticalidad se menciona en prácticamente todas las especificaciones de pilotes,
con valores típicos que van del 1,33 al 2 por ciento. Del mismo modo, las especificaciones también limitan la tolerancia de rastrillado
pilas de su inclinación especificada. Si bien esta restricción parece fundamental para los muros de contención apilados, la
El razonamiento detrás de esta restricción para los cimientos piloteados no se comprende bien. Simulación de elementos finitos
realizado ha demostrado que superar los límites anteriores puede introducir grandes momentos flectores y fuerzas cortantes
en pilotes diseñados estrictamente para cargas axiales e incluso pueden provocar fallas estructurales.
This PPT discuss the 14 geometric symbols used in GD&T classified under five controls. Only important points are mentioned. Kindly mention, if any other important points are missed out. The sources of the content (including pics) are from various sites which details GD&T. The PPT with modifiers and additional symbols (in detail) will be updated soon.
This PPT discuss the 14 geometric symbols used in GD&T classified under five controls. Only important points are mentioned. Kindly mention, if any other important points are missed out. The sources of the content (including pics) are from various sites which details GD&T. The PPT with modifiers and additional symbols (in detail) will be updated soon.
This ppt describes Profile & Runout CONTROLS in GD&T. It also showcase the differences & similarities between the two controls. Kindly suggest your comments as required. Thank you + Regards.
*Introduction
*Controls For Setting Out
*Horizontal control
*Vertical control
*SETTING OUT A BUILDING
*The equipment required for the job
*Method(1):-By using a Circumscribing Rectangle
*Method(2):- By using centre-line-rectangle
* Setting out of culverts
*SETTING OUT A TUNNEL
The entire process of structural planning and design requires not only imagination and conceptual thinking but also sound knowledge of practical aspects, such as recent design codes and bye-laws, backed up by ample experience, institution and judgment.
It is emphasized that any structure to be constructed must satisfy the need efficiency for which it is intended and shall be durable for its desired life span. Thus, the design of any structure is categorizes into following two main types:-
1. Functional design
2. Structural design
Once the form of the structure is selected, the structural design process starts. Structural design is an art and science of understanding the behavior of structural members subjected to loads and designing them with economy and elegance to give a safe, serviceable and durable structure.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Surface roughness metrology refers to the measurement and quantification of the minute variations, irregularities, and finer details present on the surface of an object. Surface roughness is a crucial aspect in various industries, such as manufacturing, engineering, and quality control, as it significantly affects the functionality, performance, and appearance of products.
Surface roughness metrology involves the use of specialized tools and techniques to measure and characterize the topography of a surface. Some common methods and instruments used for surface roughness measurement include:
Contact Profilometers: These instruments use a physical stylus or probe that moves along the surface to measure its profile. The stylus records the vertical deviations in the surface, which are used to calculate roughness parameters like Ra (average roughness), Rz (average maximum peak to valley height), Rq (root mean square roughness), etc.
Non-Contact Profilometers: Optical and laser-based systems, such as confocal microscopy, interferometry, and focus variation, measure surface roughness without physically touching the surface. These methods use light, lasers, or other non-contact mechanisms to capture surface details.
Atomic Force Microscopy (AFM): AFM uses a tiny cantilever with a sharp tip to scan the surface at a nanoscale level, producing a 3D profile of the surface. It's highly accurate for measuring extremely small surface features and roughness.
White Light Interferometry: This method uses white light to measure the surface height variations by analyzing interference patterns produced by the reflected light.
Surface roughness measurements are typically expressed using various parameters, including:
Ra (Average Roughness): Arithmetic mean deviation of the roughness profile from the mean line.
Rz (Maximum Height of the Profile): The distance between the highest peak and the lowest valley within a sampling length.
Rq (Root Mean Square Roughness): The root mean square of the roughness profile deviations.
Understanding and quantifying surface roughness is crucial for several reasons:
Quality Control: Ensures that manufactured parts meet specified surface quality standards.
Functionality: Impacts how well parts interact, move, seal, or perform their intended functions.
Performance: Affects friction, wear, and corrosion resistance of components.
Appearance: Influences the visual and tactile perception of a product.
Accurate surface roughness metrology allows manufacturers to control and optimize their processes, resulting in better product performance, durability, and appearance.
This ppt describes Profile & Runout CONTROLS in GD&T. It also showcase the differences & similarities between the two controls. Kindly suggest your comments as required. Thank you + Regards.
*Introduction
*Controls For Setting Out
*Horizontal control
*Vertical control
*SETTING OUT A BUILDING
*The equipment required for the job
*Method(1):-By using a Circumscribing Rectangle
*Method(2):- By using centre-line-rectangle
* Setting out of culverts
*SETTING OUT A TUNNEL
The entire process of structural planning and design requires not only imagination and conceptual thinking but also sound knowledge of practical aspects, such as recent design codes and bye-laws, backed up by ample experience, institution and judgment.
It is emphasized that any structure to be constructed must satisfy the need efficiency for which it is intended and shall be durable for its desired life span. Thus, the design of any structure is categorizes into following two main types:-
1. Functional design
2. Structural design
Once the form of the structure is selected, the structural design process starts. Structural design is an art and science of understanding the behavior of structural members subjected to loads and designing them with economy and elegance to give a safe, serviceable and durable structure.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Surface roughness metrology refers to the measurement and quantification of the minute variations, irregularities, and finer details present on the surface of an object. Surface roughness is a crucial aspect in various industries, such as manufacturing, engineering, and quality control, as it significantly affects the functionality, performance, and appearance of products.
Surface roughness metrology involves the use of specialized tools and techniques to measure and characterize the topography of a surface. Some common methods and instruments used for surface roughness measurement include:
Contact Profilometers: These instruments use a physical stylus or probe that moves along the surface to measure its profile. The stylus records the vertical deviations in the surface, which are used to calculate roughness parameters like Ra (average roughness), Rz (average maximum peak to valley height), Rq (root mean square roughness), etc.
Non-Contact Profilometers: Optical and laser-based systems, such as confocal microscopy, interferometry, and focus variation, measure surface roughness without physically touching the surface. These methods use light, lasers, or other non-contact mechanisms to capture surface details.
Atomic Force Microscopy (AFM): AFM uses a tiny cantilever with a sharp tip to scan the surface at a nanoscale level, producing a 3D profile of the surface. It's highly accurate for measuring extremely small surface features and roughness.
White Light Interferometry: This method uses white light to measure the surface height variations by analyzing interference patterns produced by the reflected light.
Surface roughness measurements are typically expressed using various parameters, including:
Ra (Average Roughness): Arithmetic mean deviation of the roughness profile from the mean line.
Rz (Maximum Height of the Profile): The distance between the highest peak and the lowest valley within a sampling length.
Rq (Root Mean Square Roughness): The root mean square of the roughness profile deviations.
Understanding and quantifying surface roughness is crucial for several reasons:
Quality Control: Ensures that manufactured parts meet specified surface quality standards.
Functionality: Impacts how well parts interact, move, seal, or perform their intended functions.
Performance: Affects friction, wear, and corrosion resistance of components.
Appearance: Influences the visual and tactile perception of a product.
Accurate surface roughness metrology allows manufacturers to control and optimize their processes, resulting in better product performance, durability, and appearance.
Isolation of MIMO Antenna with Electromagnetic Band Gap StructureAysu COSKUN
This work represents isolation of mimo antenna system with mushroom type electromagnetic band gap structure in order to reduce mutual coupling between antennas.
Surface roughness metrology deals with basic terminology of surface,surface roughness indication methods,analysis of surface traces, measurement methods,surface roughness measuring instruments such as Stylus Probe Instrument, Profilometer, Tomlinson Surface Meter ,The Taylor-Hobson Talysurf etc.This is very useful for diploma,degree engineering students of mechanical,production,automobile branch
Presentation by the author of the CompNet Least Square Adjustment Software on the optimal setup and conditions in order to produce the most accurate resection traverse.
Earthquake analysis on 2 d rc frames with different aspect ratios of masonry ...eSAT Journals
Abstract
RC structures are one of the most famous and most utilized types of construction throughout the world. The wall panels for this type of
structures usually are made of masonry infill or monolithic RC panels. In this paper, earthquake analysis of a typical 2D-RC frame is
carried out. Masonry infill is modeled as equivalent diagonal strut and monolithic panel is modeled as shell element. Modal analysis
is carried out on the models and the results are compared with the shake table tests conducted at Central Power Research Institute
(CPRI), Bangalore to validate the models. Earthquake analysis is continued with equivalent static, response spectrum and time history
analyses for all the zones (II-V) as per IS: 1893(Part-1):2002. The analysis results such as natural frequency, displacement, interstorey
drift and acceleration are tabulated, compared and conclusions are drawn.
Key words: 2D-RC Frame, Masonry Infill, Monolithic wall, Shake table, Natural Frequency, Modal analysis, Response
spectrum, Equivalent Diagonal Strut, Time History, Inter-Storey drift.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Earthquake analysis on 2 d rc frames with different aspect ratios of masonry ...eSAT Journals
Abstract
RC structures are one of the most famous and most utilized types of construction throughout the world. The wall panels for this type of
structures usually are made of masonry infill or monolithic RC panels. In this paper, earthquake analysis of a typical 2D-RC frame is
carried out. Masonry infill is modeled as equivalent diagonal strut and monolithic panel is modeled as shell element. Modal analysis
is carried out on the models and the results are compared with the shake table tests conducted at Central Power Research Institute
(CPRI), Bangalore to validate the models. Earthquake analysis is continued with equivalent static, response spectrum and time history
analyses for all the zones (II-V) as per IS: 1893(Part-1):2002. The analysis results such as natural frequency, displacement, interstorey
drift and acceleration are tabulated, compared and conclusions are drawn.
Key words: 2D-RC Frame, Masonry Infill, Monolithic wall, Shake table, Natural Frequency, Modal analysis, Response
spectrum, Equivalent Diagonal Strut, Time History, Inter-Storey drift.
--------------------------------------------------------------------***--------------------------------------------------------
Online aptitude test management system project report.pdfKamal Acharya
The purpose of on-line aptitude test system is to take online test in an efficient manner and no time wasting for checking the paper. The main objective of on-line aptitude test system is to efficiently evaluate the candidate thoroughly through a fully automated system that not only saves lot of time but also gives fast results. For students they give papers according to their convenience and time and there is no need of using extra thing like paper, pen etc. This can be used in educational institutions as well as in corporate world. Can be used anywhere any time as it is a web based application (user Location doesn’t matter). No restriction that examiner has to be present when the candidate takes the test.
Every time when lecturers/professors need to conduct examinations they have to sit down think about the questions and then create a whole new set of questions for each and every exam. In some cases the professor may want to give an open book online exam that is the student can take the exam any time anywhere, but the student might have to answer the questions in a limited time period. The professor may want to change the sequence of questions for every student. The problem that a student has is whenever a date for the exam is declared the student has to take it and there is no way he can take it at some other time. This project will create an interface for the examiner to create and store questions in a repository. It will also create an interface for the student to take examinations at his convenience and the questions and/or exams may be timed. Thereby creating an application which can be used by examiners and examinee’s simultaneously.
Examination System is very useful for Teachers/Professors. As in the teaching profession, you are responsible for writing question papers. In the conventional method, you write the question paper on paper, keep question papers separate from answers and all this information you have to keep in a locker to avoid unauthorized access. Using the Examination System you can create a question paper and everything will be written to a single exam file in encrypted format. You can set the General and Administrator password to avoid unauthorized access to your question paper. Every time you start the examination, the program shuffles all the questions and selects them randomly from the database, which reduces the chances of memorizing the questions.
NO1 Uk best vashikaran specialist in delhi vashikaran baba near me online vas...Amil Baba Dawood bangali
Contact with Dawood Bhai Just call on +92322-6382012 and we'll help you. We'll solve all your problems within 12 to 24 hours and with 101% guarantee and with astrology systematic. If you want to take any personal or professional advice then also you can call us on +92322-6382012 , ONLINE LOVE PROBLEM & Other all types of Daily Life Problem's.Then CALL or WHATSAPP us on +92322-6382012 and Get all these problems solutions here by Amil Baba DAWOOD BANGALI
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Using recycled concrete aggregates (RCA) for pavements is crucial to achieving sustainability. Implementing RCA for new pavement can minimize carbon footprint, conserve natural resources, reduce harmful emissions, and lower life cycle costs. Compared to natural aggregate (NA), RCA pavement has fewer comprehensive studies and sustainability assessments.
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
Literature Review Basics and Understanding Reference Management.pptxDr Ramhari Poudyal
Three-day training on academic research focuses on analytical tools at United Technical College, supported by the University Grant Commission, Nepal. 24-26 May 2024
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)
Testing of bored_pile_inclination
1. Testing of bored pile inclination
Joram M. AMIR
Chairman, Piletest.com Ltd. JMAmir@Piletest.com
Erez I. AMIR
President, Piletest.com Ltd. Erezam@piletest.com
Keywords: deep foundations, inclination, testing, raked piles
ABSTRACT:
The allowable deviation from of piles from verticality is mentioned in practically all piling specifications,
with typical values ranging from 1.33 to 2 percent. Similarly, specifications also limit the tolerance of raked
piles from their specified inclination. While this restriction seems critical for piled retaining walls, the
reasoning behind this restriction for piled foundations is not well understood. Finite element simulation we
carried out has shown that exceeding the above limits can introduce large bending moments and shear forces
in piles designed strictly for axial loads and may even lead to structural failure. Still, the above specifications
are seldom enforced due to the lack of convenient testing apparati. In this paper, we describe the BIT
(Borehole Inclination Tester), present its details and calculation method, and show initial field results.
1 INTRODUCTION
Probably all piling specifications prescribe the
tolerances for both centricity and verticality of
piles. The following examples demonstrate
common values for allowable deviation:
“Verticality – the maximum permitted deviation
of the finished pile from the vertical at any level is
1 in 75. Rake – the maximum permitted deviation
of any part of the finished pile from the specified
rake is 1 in 25 for piles raking up to 1 in 6 and 1 in
15 for piles raking more than 1 in 6” (ICE 1996).
“The vertical alignment of a vertical shaft
excavation shall not vary from the plan alignment
by more than 20 mm per meter (1/4 inch per foot)
of depth. The alignment of a battered shaft
excavation shall not vary by more than 40 mm per
meter (1/2 inch per foot) of the distance along the
axis of the shaft from the prescribed batter”
(O’Neill and Reese 1999).
The importance of controlling the verticality of
a contiguous piled retaining wall is clear: piles
protruding excessively into an excavation for a
parking basement, for instance, may cause the loss
of parking spaces and hinder the granting of a
building permit. Strict verticality is even more
important in secant pile walls, where misalignment
can make the wall non-watertight (Fleming et al.
1994). The questions we set out to answer were
twofold.
• Why is verticality important for single
foundation piles?
• How can we quickly check conformance of
bored piles to the specifications regarding
inclination?
In the following, we shall use finite element
simulation to prove the importance of complying
with such specifications. Later on we shall present
a brief overview of existing devices which can
measure pile verticality and then describe the
system which we developed specifically for testing
pile inclination. Initial field results which we have
obtained demonstrate the viability and accuracy of
this technique.
2 TERMINOLOGY
Borehole axis – The trajectory the Kelly bar tip
follows when lowered into the borehole.
Inclination – the angle, in either degrees or
percent, between the vertical and the borehole axis
at any given depth.
2. Battered pile or raking pile – a pile purposely
constructed at an inclination.
Stop – a depth in the hole at which stabilized
inclination readings are taken.
Depth interval – the mean distance along the
borehole axis between two consecutive stops.
Deviation – the vector, measured in the
horizontal plane, from the planned borehole axis to
the actual one.
3 FINITE ELEMENT SIMULATION
To get a better understanding of the effect of
excessive inclination, we ran a two-dimensional
Plaxis simulation of a diaphragm wall 600 mm
thick and 20 m deep, embedded in soft clay. The
wall inclination was 2.5 percent from the vertical,
a mere 0.5 percent above the typically acceptable
value. We checked two cases: a free wall and a
horizontally-restrained one.
The results show the distribution of normal
force N, shear force Q and bending moment M
down the wall for both a free-headed (Figure 1)
and a fixed-headed (
Figure 2) wall. It shows clearly that even a small
excessive deviation can introduce large,
not-accounted for, shear forces and bending
moments in free walls. In restrained walls, e.g.
those connected by beams, this effect is minimal.
Although this two-dimensional simulation is not
fully-valid for three dimensional piles, the results
are at least qualitatively applicable.
Figure 1: Effect of vertical load on inclined
free-headed wall
Figure 2: Effect of vertical load on inclined restrained wall
4 EXISTING SYSTEMS
Present methods for measuring the inclination of
bored piles are invariably based on the plumb bob
principle: the instrument is hung down from the
planned center of the pile, and the distance to the
sidewalls is measured by ultrasonic sensors (Bruce
et al. 1989, Kort and Kostaschuk 2007). The
sensors are arranged in either of two fashions:
• Four transceivers in two mutually-
perpendicular sets, providing four readings per
every depth
• One rotating transceiver, giving 360º coverage.
Once the hole is completely logged, the
sidewall profile is drawn and, provided it is
relatively regular, the pile axis can be plotted and
compared to the vertical. A bonus of this approach
is that it enables the calculation of the bore
volume, an item of special interest to contractors.
An interesting and simple method, described by
Bruce et al. (1989), is the inverted pendulum in
which a buoy floating on the slurry replaced the
plumb bob.
The above systems have several drawbacks:
• They can be used only in slurry-filled holes
• They cannot be used in slender piles (when the
slenderness ratio L/d exceeds 25, a deviation of
2% or more from the vertical cannot be
measured)
• They cannot be used to measure the inclination
of raked piles
• They cannot be used to measure the inclination
of finished piles
• Some of these systems are cumbersome and
need a dedicated crane to move around the site
and an AC generator to power them.
5 THE PROPOSED SYSTEM
5.1 Description
The system is dual purpose:
• During drilling, it can be mounted on the
drilling bucket that acts as centralizer.
• In the finished pile, it can be lowered inside the
access tubes which are routinely installed for
crosshole ultrasonic testing (ASTM 2008).
The system consists of four main units (Figure
3):
3. 1. The upper unit which contains the electronic
circuitry and is mounted inside a 100 m.
cable-reel
2. The lower unit, containing a bi-axial (X-Y)
Micro Electro-Mechanical System (MEMS)
inclinometer, a MEMS gyro and a
thermometer, all packaged in a compact
waterproof housing. For drilling monitoring,
the lower unit is rigidly mounted on the drilling
bucket crossbar while for finished pile testing it
is mounted on a stabilizer that acts as both a
centralizer and a rotation-suppressor.
3. A wireless depth meter
4. A hand-held computer for recording and
presenting data
Figure 3: Schematic drawing of the system components
The lower unit transmits the data to the upper
one via a cable that runs over the depth meter
wheel and operates it. The upper unit uses wireless
communication to both the depth meter and the
computer.
The actual system components are depicted in
Figure 4.
5.2 Operation - Drilling configuration
After the hole is drilled to the desired depth, the
lower unit is fixed on the bucket cross bar and
inserted into the hole while pointing to the
reference north. The inclination and azimuth are
measured at ground level and then at
predetermined stops until the drilling bucket
reaches the bottom of the hole. The procedure is
then repeated on the way up, with readings taken at
the same stops as before. During the whole
procedure, the rig operator should keep Kelly bar
rotation to a minimum (although some degree of
unavoidable rotation is tolerable). When the bucket
returns to the surface, it is aligned back with the
reference north, and a final reading taken. Typical
test duration is in the order of 10 to 15 minutes.
5.3 Operation - Access tube configuration
The lower unit with the stabilizer is inserted
into the access tube pointing to the reference north.
The inclination and azimuth are measured at pile
head level and then at predetermined stops until
the unit reaches the bottom of the tube. The
procedure is then repeated on the way up, with
readings taken at the same stops as before. When
the unit returns to the surface, it is aligned back
with the reference north, and a final reading taken.
Figure 4: The BIT system
5.4 Calculations (Figure 5)
1. For each stop numbered [n], with sensor
heading hn, the inclinations Xn and Yn in the X
and Y directions, respectively, are transformed
to inclinations in the North and East directions
by the following relationships.
)
sin(h
·
Y
-
)
cos(h
·
X
IncEast n
n
n
n
n +
= (1)
)
cos(h
·
Y
-
)
sin(h
·
X
-
IncNorth n
n
n
n
n = (2)
2. For each stop numbered [n] at depth = Dn, the
deviations of the pile axis in the N-E directions
are calculated as follows.
4. 0
DevEast1 = (3)
0
DevNorth1 = (4)
)
2
tan(
)
(
DevEast
DevEast
1
1
1
-
n
n
−
−
+
⋅
−
+
=
n
n
n
n
IncEast
IncEast
D
D
(5)
)
2
tan(
)
(
DevNorth
DevNorth
1
1
1
-
n
n
−
−
+
⋅
−
+
=
n
n
n
n
IncNorth
IncNorth
D
D
(6)
Figure 5: Inclination and deviation explained
And the combined deviation expressed as a polar
vector is:
n
n
n r
Dev θ
∠
= , (7)
where
2
2
n
n
n DevEast
DevNorth
r +
= (8)
=
n
n
n
DevNorth
DevEast
arctan
θ
(9)
3. Ideally, for the final surface reading N, the
final calculated deviation rf should be zero.
4. If the closure error rf is less than a
pre-determined threshold value (expressed as a
fraction of pile length), it is proportionately
distributed among all stops.
5. If the closure error rn exceeds the threshold
value the operator receives a warning and may
decide to repeat the test.
6. For each stop, the corrected downward and
upward deviations are averaged and
transformed to polar coordinates.
5.5 Calibration
Since the specifications typically allow a deviation
in the order of only 1 to 2 percent, the system
accuracy should be at least one order of magnitude
smaller or better than 0.1%.
MEMS components are generally sensitive to
temperature changes. To achieve the required
accuracy, these components should be carefully
calibrated before the test, as follows:
Inclinometer calibration: The lower unit is
placed on a hard, smooth, horizontal surface and
stabilized inclination readings for both axes taken.
The lower unit is then rotated 1800
and the
procedure repeated. The mean X and Y readings,
respectively, are the level (or zero inclination)
readings.
Gyro calibration: MEMS gyro devices tend to
drift at a fairly constant rate. To compensate for
this drift the lower unit is laid stationary until the
rate of drift is constant, at which time it is
recorded.
Depth meter: A typical distance of 5 to 10 m is
marked on the cable and pulled over the depth
meter wheel.
5.6 Reporting
In addition to project and pile identification, the
report typically includes graphic presentation of
the results in two forms (Figure 6).
1. Top view of the pile axis superimposed on a
number of concentric circles showing the
radii in meters
2. Side view in which the maximum deviations
measured in all stops are connected by straight
lines on the background of a funnel depicting
the allowable deviation.
5. Figure 6: Typical results
6 CONCLUSIONS
Excessive inclination can be detrimental to piles
which were planned to be vertical, by introducing
large bending moments and shear forces. This
effect is much more prominent when the piles
heads are free to move.
The system presented is a portable instrument
for measuring the deviation of bored piles from the
vertical with accuracy within 0.1%. It may
therefore assist the geotechnical engineer to
enforce the specification for pile verticality. The
system may also serve piling contractors who have
to meet strict verticality tolerances in contiguous
and secant piled walls. In addition, it can help the
contractors to evaluate the suitability of specific
rigs to difficult site conditions, such as the
presence of boulders or rock.
7 REFERENCES
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