Research than the base resistance for a

 Research Proposal

 

 

An
Experimental investigation on shaft resistance cast in situ bored piles in
sound rock

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S.Suloshini

140608J

Supervisor:

 

Dr. L.I.N. de Silva

 

 

 

 

 

 

12thJanuary,
2018

 

Department of Civil Engineering

Faculty of Engineering

UNIVERSITY OF MORATUWA-SRI
LANKA

 

 

 

 

Table of Contents
Introduction. 1
Problem Statement 1
Significance of the
research. 2
Scope of the study. 2
Aims and Objectives of
the research. 2
Hypothesis (if any) 3
Review of the literature. 3
Proposed Methodology. 3
Time schedule/work plan. 4
Budget/estimated cost
built up. 4
References. 5
 

 

 

Introduction

Nowadays in the construction industry the pile foundation
socketed into the rock plays a key role in the high rise buildings due to the
high bearing capacity and minimum settlement. The bearing capacity of the rock
socketed piles contains two basic components, base resistance and shaft
resistance or skin friction. Shaft resistance is more significant when
calculating the bearing capacity of the pile because shaft resistance is
induced earlier than the base resistance for a very small movement. And the
base resistance needs the pile base free from debris. It is difficult to
achieve this condition in the practical situation. Therefore shaft resistance
is considered as an important part in designing the pile foundation. First
shaft resistance of the pile should be estimated to evaluate the bearing
capacity of the pile foundation. This research focus on the experimental investigation on shaft resistance of cast in
situ bored piles in sound rock.

Many
research have been carried out in this area and from those studies it is found
that the shaft resistance of the rock socketed pile is governed by the several
parameters like mechanical properties of the surrounding rock, RQD value of the
surrounded rock, pile diameter, roughness of the rock – concrete interface,
discontinuities of the rock, the radial force induced by the load and the rock
type. The shaft resistance should be evaluated correctly for the safety of the
structure. The under estimation of the shaft resistance is not economical but
it is conservative. Therefore the designers must pay attention on this.

Problem Statement

The investigation of the shaft resistance of the pile – rock
interface is a very complex problem because many factors should be considered
and the lack of knowledge in shaft resistance. The knowledge of shaft
resistance is necessary for the designing of the structure safely and
economically. Empirical methods are used in calculation process of shaft
resistance. Those empirical methods may not be reliable for some cases.

 

From the literature survey it is noticed that several
studies have been carried out on the shaft resistance of the cast in situ bored
piles socketed in sound rock all over the world. Even though there is no proper
investigation for the shaft resistance of rock socketed piles. The main problem
of the design engineers is the value of the shaft resistance of the underlying
rock. This study is to evaluate the shaft resistance of the rock socketed piles
for different types of rock.

Significance of the research

Pile foundation is used in the heavy loaded structures like
bridges, high rise building complex. The piles are socketed into the sock to
increase bearing capacity. The bearing capacity of the pile foundation can be
increased by introducing the rock socketed piles. The applied load is
transferred to the bed rock in the rock socketed piles. The bearing capacity of
the rock socketed pile foundation depends on the shear strength of the rock-
concrete interface. The shaft resistance is mainly governed by the roughness of
the concrete- rock interface.

For
the safety of the structure the shaft resistance should be estimated correctly.
In the normal practice the shaft resistance is calculated using empirical
methods. It is not economical. In the Engineering practice all the design and
construction works should be done to optimize the cost. Mostly the geotechnical
engineers need the shaft resistance between the piles – rock interface in their
design process.

The
shaft resistance varies with the type of rock type. Most of the methods which
are available to calculate the shaft resistance are empirical. So it may not be
correct for other types. The significance of this study is to provide more
understanding about the shaft resistance. From this study the ultimate shaft
resistance of the rock socketed can be evaluated which is helpful in the design
process of the pile.

Scope of the study

The scope of this study is to develop a fundamental
knowledge on shaft resistance of the rock – concrete interface. This is a fully
laboratory experimental study. All the tests will be conducted in the
laboratory. The shaft resistance is calculated using the rock sample.

Aims and Objectives of the
research

The aim of this study is to investigate the shaft resistance
of cast in situ bored piles in sound rock through laboratory experiment.

Hypothesis (if any)

 

Review of the literature

Many researchers have carried out their researches on the shaft resistance
of the bored piles in rock. Most of the researches have been conducted to find
the parameters which are affecting the shaft resistance or shear strength of
the intermediate surface between concrete and rock. From those studies it is
concluded that the factors affecting the shaft resistance are strength of rock
material, rock mass, RQD, roughness of pile-rock interface, diameter of the
pile, fracturing of the rock etc. The studies have been done according to
different theories like cavity expansion theory, fractal theory etc. The shaft
resistance correlations are different to country to country and they have
proposed different equation. Many empirical relationships have been proposed to
calculate the shaft resistance.

Proposed Methodology

Literature survey would be carried out to identify the
findings on this topic up to now. The methods which the researchers were
followed, factors affecting the shaft resistance, problems in finding the shaft
resistance, the existing methods to estimate the shaft resistance of the rock
socketed piles will be studied.

The intact rock samples would be collected from the field
and brought to the laboratory. The rock sample will be cut in an angle using
the rock cutter. The concrete will be placed on the top of the sample to get
the concrete – rock interface. Then the sample will be tested in the triaxial
apparatus. The shear strength of the concrete – rock interface will be
calculated.

The above mentioned procedure will be proceeded by changing
the rock type. The results obtained from the test will be analyzed.

Time schedule/work plan

 

 

Work
breakdown

November

December

January

Febrary

March

April

May

June

July

Literature
review

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Collecting
samples

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Laboratory
Experiment

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Analyzing
results

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Budget/estimated cost built up

 

References

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                                                                                                      

 Research Proposal

 

 

An
Experimental investigation on shaft resistance cast in situ bored piles in
sound rock

We Will Write a Custom Essay Specifically
For You For Only $13.90/page!


order now

 

 

 

 

S.Suloshini

140608J

Supervisor:

 

Dr. L.I.N. de Silva

 

 

 

 

 

 

12thJanuary,
2018

 

Department of Civil Engineering

Faculty of Engineering

UNIVERSITY OF MORATUWA-SRI
LANKA

 

 

 

 

Table of Contents
Introduction. 1
Problem Statement 1
Significance of the
research. 2
Scope of the study. 2
Aims and Objectives of
the research. 2
Hypothesis (if any) 3
Review of the literature. 3
Proposed Methodology. 3
Time schedule/work plan. 4
Budget/estimated cost
built up. 4
References. 5
 

 

 

Introduction

Nowadays in the construction industry the pile foundation
socketed into the rock plays a key role in the high rise buildings due to the
high bearing capacity and minimum settlement. The bearing capacity of the rock
socketed piles contains two basic components, base resistance and shaft
resistance or skin friction. Shaft resistance is more significant when
calculating the bearing capacity of the pile because shaft resistance is
induced earlier than the base resistance for a very small movement. And the
base resistance needs the pile base free from debris. It is difficult to
achieve this condition in the practical situation. Therefore shaft resistance
is considered as an important part in designing the pile foundation. First
shaft resistance of the pile should be estimated to evaluate the bearing
capacity of the pile foundation. This research focus on the experimental investigation on shaft resistance of cast in
situ bored piles in sound rock.

Many
research have been carried out in this area and from those studies it is found
that the shaft resistance of the rock socketed pile is governed by the several
parameters like mechanical properties of the surrounding rock, RQD value of the
surrounded rock, pile diameter, roughness of the rock – concrete interface,
discontinuities of the rock, the radial force induced by the load and the rock
type. The shaft resistance should be evaluated correctly for the safety of the
structure. The under estimation of the shaft resistance is not economical but
it is conservative. Therefore the designers must pay attention on this.

Problem Statement

The investigation of the shaft resistance of the pile – rock
interface is a very complex problem because many factors should be considered
and the lack of knowledge in shaft resistance. The knowledge of shaft
resistance is necessary for the designing of the structure safely and
economically. Empirical methods are used in calculation process of shaft
resistance. Those empirical methods may not be reliable for some cases.

 

From the literature survey it is noticed that several
studies have been carried out on the shaft resistance of the cast in situ bored
piles socketed in sound rock all over the world. Even though there is no proper
investigation for the shaft resistance of rock socketed piles. The main problem
of the design engineers is the value of the shaft resistance of the underlying
rock. This study is to evaluate the shaft resistance of the rock socketed piles
for different types of rock.

Significance of the research

Pile foundation is used in the heavy loaded structures like
bridges, high rise building complex. The piles are socketed into the sock to
increase bearing capacity. The bearing capacity of the pile foundation can be
increased by introducing the rock socketed piles. The applied load is
transferred to the bed rock in the rock socketed piles. The bearing capacity of
the rock socketed pile foundation depends on the shear strength of the rock-
concrete interface. The shaft resistance is mainly governed by the roughness of
the concrete- rock interface.

For
the safety of the structure the shaft resistance should be estimated correctly.
In the normal practice the shaft resistance is calculated using empirical
methods. It is not economical. In the Engineering practice all the design and
construction works should be done to optimize the cost. Mostly the geotechnical
engineers need the shaft resistance between the piles – rock interface in their
design process.

The
shaft resistance varies with the type of rock type. Most of the methods which
are available to calculate the shaft resistance are empirical. So it may not be
correct for other types. The significance of this study is to provide more
understanding about the shaft resistance. From this study the ultimate shaft
resistance of the rock socketed can be evaluated which is helpful in the design
process of the pile.

Scope of the study

The scope of this study is to develop a fundamental
knowledge on shaft resistance of the rock – concrete interface. This is a fully
laboratory experimental study. All the tests will be conducted in the
laboratory. The shaft resistance is calculated using the rock sample.

Aims and Objectives of the
research

The aim of this study is to investigate the shaft resistance
of cast in situ bored piles in sound rock through laboratory experiment.

Hypothesis (if any)

 

Review of the literature

Many researchers have carried out their researches on the shaft resistance
of the bored piles in rock. Most of the researches have been conducted to find
the parameters which are affecting the shaft resistance or shear strength of
the intermediate surface between concrete and rock. From those studies it is
concluded that the factors affecting the shaft resistance are strength of rock
material, rock mass, RQD, roughness of pile-rock interface, diameter of the
pile, fracturing of the rock etc. The studies have been done according to
different theories like cavity expansion theory, fractal theory etc. The shaft
resistance correlations are different to country to country and they have
proposed different equation. Many empirical relationships have been proposed to
calculate the shaft resistance.

Proposed Methodology

Literature survey would be carried out to identify the
findings on this topic up to now. The methods which the researchers were
followed, factors affecting the shaft resistance, problems in finding the shaft
resistance, the existing methods to estimate the shaft resistance of the rock
socketed piles will be studied.

The intact rock samples would be collected from the field
and brought to the laboratory. The rock sample will be cut in an angle using
the rock cutter. The concrete will be placed on the top of the sample to get
the concrete – rock interface. Then the sample will be tested in the triaxial
apparatus. The shear strength of the concrete – rock interface will be
calculated.

The above mentioned procedure will be proceeded by changing
the rock type. The results obtained from the test will be analyzed.

Time schedule/work plan

 

 

Work
breakdown

November

December

January

Febrary

March

April

May

June

July

Literature
review

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Collecting
samples

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Laboratory
Experiment

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Analyzing
results

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Budget/estimated cost built up

 

References

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                                                                                                      

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