Theory of Pure Bending of Sheeting

For the structural analysis of sheet piling, the primary  object is to analyse failure due to excess bending moment and stresses. Most of the analysis of cantilever and anchored walls involve the computation of pure bending. For the case of pure bending, the maximum allowable bending moment is given by the equation.

Equation 2-2: Mallow = Smin σ allow

where

  • Mallow = Allowable bending moment
  • Smin = Minimum Section Modulus

Both the allowable bending moment and the section modulus are specified as per lineal foot or meter of wall. The strength of sheet piling to resist bending is a combination of the shape of the section and the material out of which it is made. The allowable stress of the material is a function of the material itself.

(This article comes from Pile Buck International editor released)

Different Sheet Piling driving hammers

Methods for steel sheet pile construction are classified as follows.

1. Vibration method using vibrating pile hammer;
2. Pile jacking method using pile jacking machine;
3. Pile jacking method using spiral drill;
4. Piling method using pile hammer
For hard foundation, water jetting method could be used with.

1. Vibration method using vibrating pile hammer

This is a construction technique that drives steel sheet pile into earth by transferring the vertical vibration generated by vibrating pile hammer. In default of hitting power, the head of steel sheet pile would not be damaged, which contributes to a relatively high construction efficiency; this technique is applicable for both driving and extraction of pile. However, the instantaneous current is extremely high in case of electric vibration, so large-scale electrical equipment is required; in case of hydraulic vibration, dedicated hydraulic unit is a must under most circumstances.

Recently, machines that are suitable for low-noise and low-vibration construction method and for construction under beam or in small space have been put in operational service.

2. Pile jacking method using pile jacking machine

This is a construction technique that presses steel sheet pile into earth using the counter-force of drive-in steel sheet pile by clamping the intermediate section of steel sheet pile.

The main body of machine is very compact and applicable for construction under beam, but steel sheet piles need to be lifted with additional cranes.

This technique is suitable for soft foundation and can realize low-noise and low-vibration construction.

3. Pile jacking method using spiral drill

With respect to this construction method, steel sheet pile is pressed in using hydraulic press during or after drilling; in this construction technique, both the drilling mechanism of spiral drill and the penetration mechanism of steel sheet pile is provided. Thanks to the use of sleeve, a high rigidity is realized during penetration, so this technique is suitable for hard foundation. Furthermore, this construction method can realize low-noise and low-vibration construction.

4. Piling method using pile hammer

This construction method features large hitting power, mobility, high hitting frequency and operational abundance; however, feasible pile hammer must be selected so as to prevent compression failure of pile head during hitting.

Since this construction technique makes high noise and vibration, its use in surrounding areas of residential district, school and hospital etc. and designated areas is restricted; hence, it is rarely used in harbor district.

Pile hammer is classified into diesel engine driven pile hammer, hydraulic pile hammer, monkey and pneumatic pile hammer etc.

Steel piling in marine applications: Types, durability and installation

Demand for larger and deeper berthing facilities at harbours and ports is constantly increasing to satisfy the expansion of world trade. The Port Engineer has a range of construction techniques available when planning new structures, and steel piling is often the material of preferred choice for qualities of robustness, reliability, and speed of installation compared to other options. This paper presents an overview of steel pile types, their durability, and the methods of installation and driving equipment most commonly used in maritime situations.

Steel pile types

Bearing piles

Universal H Piles are low displacement piles particularly beneficial for penetrating dense stratums and hard rock. They are generally used in buried structures where the pile shaft is fully supported to prevent buckling failure about the weak axis of the profile. Soil heave and transmission of ground vibrations during installation are low compared to other pile types.

Tubular Section Piles are the most widely used steel bearing pile type and are suitable for supporting deep water structures such as jetties and dolphins. They are available in a large range of diameters, wall thickness and steel quality. A symmetrical radius of gyration allows long unrestrained lengths in open water to resist buckling failure and provide flexural strength for horizontal berthing and environmental forces.

Fabricated Box Piles are formed by connecting together individual sheet piles to form close sided sections. They can be transported from the rolling mill in single bars to be welded together on the job site. By using special corner elements and driving sequentially, it is possible to create significant load bearing foundations without the need for heavy pile driving equipment. In respect of design and installation, they have similar attributes to tube piles.

Interlocking piles for earth retaining structures

Interlocking steel sheet piles supported by tie rods and anchoring systems are prolific in harbour works. However, the demand to build very deep structures often requires profiles which have much greater strength and robustness than standard proprietary pile sections. CombiWalls and High Modulus Walls consist of tubes, box or I section ‘primary’ members interlocked with ‘secondary’ panels of Z or U profile sheet piles, and are used for deep water berths because of their high strength characteristics.

Straight Web Piles are commonly used in circular cofferdams to form self supporting gravity structures for dock closures, quay walls and breakwaters. Maximum depths and diameters of cells are limited only by strength of the bulb interlocks and also practicalities associated with installation.

Durability of steel structures

Up until the mid 1980’s it was accepted that corrosion of steel piles in marine applications was most severe in the splash and intertidal zone just above low water. However, engineers have become increasingly aware of a sinister form of bacterially induced concentrated rust termed ‘accelerated low water corrosion’ (ALWC) which manifests itself as a bright orange bloom giving off a pungent odour when disturbed. The rate of corrosion is extreme, and, unlike other corrosion mechanisms, ALWC is unpredictable as to where it will occur and its severity.

Selecting the right type of pile and other design criteria can create sustainable solutions to the problem of concentrated corrosion. The design life of the steel depends on the combined effect of imposed stresses and corrosion. For earth retaining walls, avoiding maximum stresses at or near low water by astute positioning of tie rods is desirable. Steel grades can be improved so that corrosion does not impair the strength to the same degree and the same effect can be achieved by selecting heavier section piles to provide a sacrificial thickness of steel. Protective coatings can also be used to delay the onset of rusting. High quality durable paint systems increase effective life by up to 20 years.

(This article comes from PORT TECHNOLOGY editor released)

SHEET PILING INSTALLATION

Sheet piling installation is achieved by hammering or vibrating steel sheet sections into the ground. The sheets have interlocking edges so that a continuous wall can be realised, enabling a safe excavation. In most cases a sheet piling installation is realised with steel sheets, but concrete sheet piles have been in use for over a hundred years as well to create a very durable construction which requires little maintenance. Installation of sheet piling is a widely used method by steel sheet piling contractors in order to create space to build structures such as parking garages, foundations and cofferdams. Also in water environments the installation of sheet piling allows contractors to build seawalls, quay and bulkheads. The interlocked sheet piles form a wall for permanent or temporary lateral earth support with reduced groundwater inflow.

METHOD TO REALISE SHEET PILING INSTALLATION

A commonly used method to realise sheet piling installation is by using vibratory hammers. Traditional pile drivers use a large weight to strike a sheet which has quite a few disadvantages in the sense of noise and vibrations. Vibratory hammers however use spinning counter-weights to create vibration to the sheet, which allows it to easily cut into the ground. In areas where even these hammers create too much inconvenience, the sheets can also be hydraulically pushed into the ground, if soil conditions allow it. Clearly, for applications in inner cities the vibration-free silent sheet piling technique is often preferable. In this way, sheet piling installation is vibration free and there is little noise production.

(This article comes from piledrivershop.com editor released)

Design Procedure of Sheet Piles In Sand

This is a procedure to design a sheet pile cantilever in sand and covers all the details you need to design them.

This very useful design procedure has been uploaded here with an aim to help civil engineers make the design process simpler. We are thankful to a engineer Sadaf Noor Ahmed for this valuable contribution and hope to see more such valuable information from her.

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We are thankful to a engineer Sadaf Noor Ahmed for this valuable contribution and hope to see more such valuable informations from her.

(This article comes from www.engineeringcivil.com editor released)

Design Guide for Steel Sheet Pile Bridge Abutments

A design basis is presumed based on limit state design principles, and is written with reference to UK construction legislation, DETR Highways Agency Specifications, UK Codes of Practice, and European Standards.

Awareness of the type of soil data that is required to perform an accurate design is very important, therefore the document focuses on the importance of high quality site investigations and the selection and evaluation of soil parameters for use by the structural designer.

Both limit equilibrium methods based on classical theory of soil mechanics, and soil-structure interaction methods are presented to determine the earth pressure forces acting on the sheet piles.

Bridge abutments also have to resist vertical loads from the bridge superstructure, therefore methods to determine the axial capacity of steel sheet piles in different soil types are covered by reference to the SCI publication Steel bearing piles guide.

As construction and installation are important aspects of design, there are sections on pile driving installation methods and equipment, driveability, construction tolerances, and noise and vibration during sheet pile driving.

The long-term performance of a bridge abutment has to be ensured, therefore design for durability is a major requirement.

This necessitates that realistic rates of corrosion are used, and that protection to the sheet piles is provided where necessary.

(This article comes from JD Fields editor released)

STEEL SHEET PILES

One of the easiest and quickest ways in which to form a watertight retaining wall, in soft or loose saturated soil profiles, is to use steel sheet piles.  These are steel sections which have the facility to interlock, one with another, and which can be driven into the ground to form a watertight wall.  The sheet pile sections can be extracted once they have performed the function for which they were installed, reducing costs considerably.  The steel sheet piles can either be used as cantilever walls or as braced / tie-back walls.

Positive Features

  • Fast method for forming a wall or cofferdam in soft or loose saturated soil profiles
  • Sheet piles can be extracted and used many times, thus reducing costs
  • Wall flexibility can be used in the design to reduce wall pressures, leading to economical designs

Typical Uses of / Need for Sheet Pile Installation

  • Temporary cofferdam for the construction of the pile-cap for a pier in a river
  • Temporary cofferdam for the construction of a pump-house below ground level
  • Temporary cofferdam for the construction of a basement to a building
  • Permanent wall as part of the construction of a harbour quay
  • Permanent cut-off wall to restrict the flow of groundwater
  • Temporary or permanent retaining walls

As the cost of steel sheet piles is high, their use is generally only justified economically for temporary support of excavations below the water-table in soft saturated soil profiles.  Despite the high costs, sheet piles are often used for certain permanent works or in situations where the speed of installation is a distinct advantage.  They are commonly used in marine construction.

(This article comes from Franki Africa editor released)

Braced sheet piling walls with ground anchors

The bracing of sheet piling walls using ground anchors facilitates deep excavations whilst leaving the area free of obstacles.

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  • This method enables the undertaking of deep excavations whilst limiting deformation to the wall.
  • Providing it is possible to implement this method, the use of anchors for bracing sheet piling screens enables the undertaking of excavations in the proximity of elements which must be protected (buildings, installations, communications networks, etc.).
  • The excavation must be carried is needed more than one phase in order that the anchors can be installed and stress tested before proceeding with the other work.
  • This type of bracing makes it possible to undertake the excavation of large enclosures in a variety of geometries.
  • The excavation remains completely free of obstacles, enabling the optimum performance of the work to be carried out in its interior.

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(This article comes from www.ischebeck.es editor released)

Repair and corrosion protection of steel sheet pile walls

In sea-water, especially in the variable waterline zone, sheet piles are exposed to major corrosive damages. Precedents are known, when over the years of operations, sheet pile walls were found with multiple holes through the whole section of the element, caused by corrosion.

Repair works in the zone of variable water level are performed in air-dry environment, using patented special underwater equipment – hermetic chamber. Works are performed keeping the structures in operational conditions. The repair technology depends on the degree of damages.

If the corrosive wear is less than 30% of the initial metal thickness, it will be sufficient to apply an anticorrosive coating on the steel surface. From the hermetic chamber the steel surface is blast cleaned and then a primer and a protective coatings are applied. Used materials are thoroughly selected, have the required certificates and have passed through long-term testing.

In presence of significant sheet piles damages and depending on the environmental conditions and Client request, a thin reinforced concrete wall could be built directly on the sheet piling surface or additional metallic elements could be added to the structure to increase the section. In underwater zone cathodic protection is applied.

(This article comes from GT Corporation editor released)

Steel Pile Installations

Sheet Piling is the holding back or retaining of substances, i.e. earth, water etc. as against Steel Piling which is designed for structural and load bearing applications.

The piles has a mechanical connection “Interlock” at both ends of the section to enable to interlock to form a continuous wall of sheet piling. They are typically designed to create a rigid barrier for earth and water while resisting the lateral pressures of those bending forces. Sheet Piling is versatile and widely used as a quick and economical method of installing cofferdams and retaining walls, both on temporary works and permanent structures. We can also do Jagged wall piling.

Due to their versatility Sheet Piles can be used for River and Coastal Protection, Docks, Quaysides, Underground Basements, Covered Tunnels, Embankment Supports, Containment in contaminated areas, as all piles can be sealed using sealant to form a water tight seal.

Sheet Piles are used when installing cofferdams. Cofferdams come in many shapes and sizes. The circular cofferdam will also have H Piles installed, also known as UBPs or Universal Bearing Piles and also used in Steel Piling. The properties of steel mean that they can be used to resist tensile as well as comprehensive loads and they can be designed for bending. These piles provide excellent impact resistance and high strength in both compression and tension.

The Sheet Piles can be installed/extracted using conventional methods, ie vibratory or percussive, when the ground conditions are straightforward, and we have a selection of ABI Telescopic Leader Rigs with Vibratory Hammers, Hydraulic Impact Hammers, Auger Drives and several Movax units to go on our 38T Excavators.

Impact Driving is the best method for driving piles into difficult ground conditions or the final driving of piles to level in panel form. With the correct hammer it is the most effective way of completing deep penetration into hard soils in most conditions. The downside is that it is noisy and not suitable for sensitive or restricted areas.

We also use silent vibrationless techniques with our Tosa WP150 Stillworker Pile Press System. Pressing or silent and vibrationless methods are very effective in clay soils, less so in dense cohesionless ground unless pre-augering or jetting techniques are used. This is the most effective method when installing sheet piles in sensitive or restricted areas, adjacent to structures, built up areas, cities, railways etc.

(This article comes from aeyates.co.uk editor released)