Chapter 1. Proposal
Background
I was
attached with Bauer Foundation Singapore for my internship. Headquartered in
Germany, Bauer Group is a renowned international conglomerate specializing in construction
and machinery manufacturing, with its inception dating back to 1970. The
company operates across three core segments: Construction, Equipment, and
Resources. Under the Construction segment, spearheaded by BAUER Spezialtiefbau
GmbH, Bauer Group excels in executing specialized foundation engineering tasks
for intricate excavation pits and foundations in largescale infrastructure and
building projects.
This includes
the installation of cut-off walls, ground improvement works, and provision of
comprehensive project development services. Bauer Foundations Singapore, a
subsidiary of Bauer Spezialtiefbau GmbH, extends the company’s expertise to the
vibrant market of Singapore and its neighboring regions. Specializing in a
diverse array of foundation services, including bored piles, diaphragm walls,
earth retaining systems, ground improvement, and deep excavation support
systems, Bauer Foundations Singapore is committed to delivering high-quality
solutions tailored to meet the unique demands of the local construction landscape.
During my
tenure at Bauer Singapore, I served as a site engineer for Project J120: Design
and Construction of the Integrated Transport Hub at Jurong East.
One of the
main challenges faced by the project is the challenging ground condition of the
worksite due to the presence of large amount of silty clay on certain areas. This
causes the collapse of trenches during the early stages of the project and contamination
of concrete due to presence of silty clay during concrete casting.
Objective
The primary
goal of this comprehensive analysis is to elevate the overall efficiency and effectiveness
of the J120 Diaphragm Wall construction project and specifically to investigate
the impact of silty clay on the construction progress and to identify
strategies for mitigating its adverse effects.
Firstly, the
analysis will delve into the investigation of overbreak occurrences, a
critical
concern in diaphragm wall construction. This phase involves a exploration of factors
contributing to overbreak, considering ground conditions and leveraging
existing data from sources such as Koden Radar and B-Tonic display.
The objective
is to discern and mitigate variables causing overbreak in specific regions of the
construction site. By systematically correlating borehole data with instances
of overbreak and conducting a thorough assessment of ground conditions, the
analysis seeks to provide valuable insights on the ground conditions of J120.
Furthermore, the analysis will explore
the occurrences of trench collapse and concrete contamination encountered
during the initial phases of the project, largely attributed to the presence of
silty clay. This investigation will entail a series of experiments utilizing
the silty clay and the associated supporting fluid utilized in the diaphragm
wall construction process.
Proposed Method
1. Overbreak
Analysis with Ground Condition Influence
The first segment of the project is dedicated to an extensive analysis
of overbreak,
with a particular emphasis on the influence of ground conditions. To
undertake this
analysis, the project will leverage existing data obtained from various
sources, including Koden Radar, B-Tonic display, and records of concreting
activities.
Koden radar is a device that uses ultrasound technology to map out the
alignment of the
excavated trenches, the device is to ensure that the deviation of the
trench from
perpendicular and any surface cavities in the trench are measured.
Therefore, any
deviation out of acceptable range will be recorded, it will be able to
identify location that might be under excavated or over excavated.
B-Tronic display is a system that is equipped in every Bauer rig, which
records all relevant data of the rig operation. Together with the built-in
inclinometer which provides inclination of the excavation live to the operator.
Therefore, differentiate panels within the J120 Diaphragm Wall
construction site that exhibit overbreak conditions that is cause by operators
or ground condition. Subsequently, a comprehensive on-site borehole data
collection effort will be initiated specifically in the areas identified with
overbreak due to ground conditions.
This step is crucial for gaining insights into the underlying soil
composition and ground conditions that may be contributing to the occurrence of
overbreak. The collected borehole data will then be systematically correlated
with instances of overbreak, aiming to discern and pinpoint the variables that
play a significant role in causing overbreak in specific regions. In parallel,
the project will conduct a detailed analysis to determine the necessity for
backfill in panels that exceed tolerance ranges for overbreak, proposing
appropriate measures to address such scenarios. Furthermore, a comparative
assessment of the cement requirements for finishing casting in the identified
panels will be conducted.
This comparative analysis involves cross-referencing the data to unveil
potential patterns or anomalies that may offer valuable insights for refining
construction practices and mitigating overbreak challenges in the J120.
2.
Assessing the influence
of various supporting fluids on Silty Clay.
The second phase of
the project involves experimentation with silty clay, employing various
supporting fluids, notably Polymer and Bentonite. Supporting fluids are crucial
for stabilizing trenches during excavation. Unfortunately, in the project’s
initial stages, trench collapses occurred, attributed to the use of polymer as
a supporting fluid. To investigate the underlying causes of these collapses,
silty clay will be combined with the two aforementioned supporting fluids at
different concentrations. The rheological properties of the resulting mixtures
will be assessed to ascertain how silty clay impacts the performance of the
supporting fluids. Ultimately, this analysis aims to determine the optimal
dosage of supporting fluids mixed with silty clay that aligns with LTA
standards.
