Construction Temporary Works and Excavation

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Questions and Answers

Sheet piling is an earth retention and excavation support technique that retains soil using sheet sections with interlocking ______.

edges

Sheet piles are installed in sequence to design depth along the planned excavation ______.

perimeter

Sheet piles can be used for temporary and ______ structures.

permanent

The work using sheet piles is neat, clean, and creates no ______ arisings.

spoil Signup and view all the answers

Cofferdams constructed with sheet piles can be in almost any desired ______.

shape Signup and view all the answers

Piling rigs are composed of a series of leaders, which are a tubular element or ______ box.

hard Signup and view all the answers

The prime goal of piling winches is to lift the hammer and ______ in addition to supporting tools.

piles Signup and view all the answers

Hanging leaders are specifically designed to be hanged from the ______ of a crane.

jib Signup and view all the answers

The principal purpose of excavation in construction is to create building ______.

foundations Signup and view all the answers

Sheet piling is often used to create a ______ that provides stability for construction projects.

barrier Signup and view all the answers

Shallow foundations are typically used for structures where the soil close to the ______ can support the load.

surface Signup and view all the answers

Deep foundations, such as piles, are used when ______ soil layers cannot support the load.

surface Signup and view all the answers

Excavation is a process that involves moving earth, rock, or ______ using various methods.

materials Signup and view all the answers

In construction projects, equipment such as cranes and piledrivers are crucial for ______ works.

temporary Signup and view all the answers

Propping and shoring are used to ensure stability during the ______ phase of construction.

excavation Signup and view all the answers

Construction hoists and mast climbing work ______ are used to facilitate access during the build process.

platforms Signup and view all the answers

The fluid used in construction is called ______.

Bentonite Signup and view all the answers

Underpinning is a method used for repair and strengthening of building ______.

foundations Signup and view all the answers

The mass concrete underpinning method is the traditional method of underpinning, followed for ______.

centuries Signup and view all the answers

One of the underpinning methods involves the use of a cantilever ______ beam.

needle Signup and view all the answers

A submersible pump connected to tremie pipes is used to pump the fluid down to the ______ level.

toe Signup and view all the answers

When hard strata is encountered, a heavy ______ may be used to break up the obstruction.

chisel Signup and view all the answers

______ method of underpinning includes techniques like mini piled and pile methods.

Pre-test Signup and view all the answers

Underpinning by cantilever needle beam is suitable when the foundation must be extended only to one ______.

side Signup and view all the answers

Study Notes

Site Temporary Works

Site temporary works (TW) refer to the essential temporary elements and structures within a construction project that are crucial for facilitating the initial phases of construction, often serving as a foundation for subsequent permanent works.
These temporary works are usually dismantled or removed following the completion of the overall construction project. Despite being temporary, they play a critical role in ensuring the project proceeds smoothly and efficiently, ultimately contributing to the timely delivery of the final structure.
Various components are classified under TW, which can typically include major categories such as: Earthworks, structures, foundations, and equipment, each serving specific functions within the construction process.
Examples of earthworks within TW encompass a range of activities and features, such as trenches that are dug for utility lines, excavations to create suitable bases for buildings or infrastructure, temporary slopes that are created for land stability or access, and stockpiles for storing soil or materials during construction.
Structures that fall under the umbrella of TW may include a variety of supportive and protective installations. These can range from formwork used to mold concrete, falsework that provides temporary support until permanent constructions are finished, propping mechanisms to hold structures in place, and façade retention systems that stabilize existing structures during renovations. Other examples include needling for stabilizing walls, shoring to secure work areas, edge protection systems to safeguard personnel, scaffolding for safe access to building heights, temporary bridges for crossing work zones, site hoarding for security and privacy, signage for safety information, site fencing to demarcate boundaries, and cofferdams used in water management.
When it comes to foundations within TW, notable examples include temporary bases for tower cranes, supports for various construction apparatus, anchors, and ties designed specifically for construction hoists that assist with vertical lifting, mast climbing work platforms meant for safe elevation during construction, and groundwork that allows for the proper erection of construction plants.
The equipment utilized during TW operations can include heavy-duty machinery like mobile cranes for lifting and maneuvering heavy loads, as well as piling rigs specifically designed for deep foundation work.

Excavation

Excavation is a fundamental construction process that involves the removal and relocation of earth, rock, or various materials, typically employing specialized tools, heavy machinery, and sometimes explosive techniques to achieve the desired outcome.
This process encompasses various activities within the realm of earthwork, such as trenching, which involves digging narrow grooves in the ground, wall shafts that require vertical excavation for structural support, tunneling for underground passages, and comprehensive underground construction operations.
Excavation serves a multitude of purposes, often being employed to create building foundations that provide a stable base for structures, to develop reservoirs designed for water storage, and to construct roadways that facilitate transportation.
The common processes associated with excavation work include trenching for utilities or foundations, digging for removal of materials, dredging for underwater excavation, and site development that involves reshaping the land for construction purposes.

Sheet Piling

Sheet piling is a specialized construction method employed for earth retention and excavation support, which utilizes long, thin sections of material known as sheet piles that possess interlocking edges designed to form a continuous wall.
The installation process of sheet piles involves placing these sections sequentially into the ground to a predetermined depth along the periphery of the intended excavation or waterfront structure, such as a seawall.
In their operational capacity, sheet piles act as temporary retaining walls that prevent the collapse of softer soil layers from higher elevations to lower levels, providing essential support during various phases of construction.
An additional advantage of sheet piles is their environmental sustainability, as they can be easily recycled, reused, and are available in a variety of sizes and materials to suit different project requirements.

Advantages of Sheet Piling

One of the critical benefits of employing sheet piling is its cost-effectiveness and speed of installation, which typically surpasses that of other methods such as contiguous or secant wall constructions.
The versatility of sheet piling allows for its usage in both temporary and permanent constructions, making it adaptable to various project needs.
Furthermore, sheet piling can be installed using operations that are silent and vibration-free, minimizing disruption to the surrounding environment and existing structures.
The installation process of sheet piles results in a neat and clean environment with minimal waste generated, contributing to more sustainable construction practices.
These structures can be customized into nearly any shape; however, they are predominantly rectangular or circular in design due to practicality and ease of implementation.
The close-fitting joints created by interlocking sheet piles ensure effective water sealing, which is particularly essential in applications where water intrusion must be minimized.
Lastly, sheet piles boast a long lifespan, comparable both above and below water, making them an excellent choice for projects situated in marine or coastal environments where durability is paramount.

Pile Driving Equipment

A range of advanced machines and equipment is utilized in construction for the process of pile driving, which involves driving structural piles into the ground to form deep foundations for various types of buildings and infrastructures.

Piling Rigs

Piling rigs are specialized equipment composed of a series of leaders, which can be described as tubular elements or rigid boxes. These are securely placed and anchored on a crane base to provide stability and accurate pile placement during the driving process.

Piling Winches

Piling winches are crucial components of the pile driving apparatus, as they are responsible for lifting the hammer and the piles themselves. Additionally, they provide the necessary support tools required for efficiently raking and rotating the leader during operation.

Hanging Leaders

Hanging leaders are specifically designed for use in conjunction with cranes, where they hang from the jib. This setup allows for the efficient alignment and placement of piles during the driving process.
To connect the assembly, a steel strut is employed to join the leader foot to the bed frame of the machine, providing the necessary support and stability required during operation.

General Procedure of Construction for Sheet Piling

The procedure for constructing sheet piles begins with dredging the soil both in front of and behind the proposed infrastructure. This operation prepares the site for the subsequent installation of the sheet piles.
After the dredging operation is complete, the next step involves driving the sheet piles into the prepared ground, which provides the necessary support and containment required for the intended excavation or structure.

Underpinning

Underpinning is a critical technique used in construction for the repair and fortification of existing building foundations that may be experiencing instability or structural issues. This method extends the depth or breadth of the foundation, reaching down to a more stable stratum to provide enhanced support.
The underpinning process is essential in situations where renovations or additional loads on the structure necessitate a stronger foundation, or in instances where soil conditions have changed, undermining the existing foundation's integrity.

Methods of Underpinning

Various methods of underpinning exist, tailored to different structural needs and soil conditions, including:
Mass concrete underpinning method (pit method)
Underpinning by cantilever needle beam method
Pier and beam underpinning method
Mini piled underpinning technique
The pile method of underpinning, which employs driven piles
Pre-test method of underpinning, often used prior to other underpinning methods to assess the existing conditions.

Mass Concrete Underpinning Method (Pit Method)

The mass concrete underpinning method, often referred to as the pit method, is considered a traditional approach to underpinning. This technique involves excavating beneath the existing foundation to extend it downward or outward, thereby reaching a stable soil layer that enhances the foundation's strength.
The process requires careful planning and execution to ensure that the rest of the structure remains stable while the excavations and modifications are taking place.

Underpinning by Cantilever Needle Beam Method

This method is essentially an extension of the pit method, where underpinning is carried out on a single side of the foundation. It is particularly suitable when the foundation only requires adjustment on one side, with the design of the building incorporating a more robust interior column that can bear additional load when the underpinning process is carried out.
This technique not only stabilizes the existing structure but also offers an efficient, effective solution to foundation issues without necessitating extensive excavation or disruption to the building’s overall integrity.

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Description

Explore the vital role of temporary works in construction projects and the excavation processes involved. This quiz covers essential temporary structures, equipment, and techniques needed for successful project execution. Understand the intricacies of earthworks and temporary structures integral for construction.