Category: Civil Engineering Articles

You can find in this section the best civil engineering articles which we found very useful and interresting

The Main Types Of Tunnels

The Main Types Of Tunnels

 

Tunnels have been used for various purposes throughout history, from transportation and infrastructure to military defense and mining. Tunnels are underground or underwater structures that allow people and vehicles to pass through an obstacle or a mountain range. There are different types of tunnels, each with its own unique features and purposes.

1.Cut-and-cover tunnels:

Cut-and-cover tunnels are constructed by digging a trench or ditch and then covering it with a roof. They are usually used for building underground structures such as subways or parking garages. Cut-and-cover tunnels are relatively shallow, and the construction process involves excavating the ground, building the walls and roof, and then backfilling the trench.

Cut-And-Cover Tunnels

2.Bored tunnels:

Bored tunnels are created by digging a tunnel through solid rock or other hard materials using a tunnel boring machine (TBM). These tunnels are typically used for transportation, such as roads, railways, or subways. Bored tunnels can be either single or double-track, and they are usually deeper than cut-and-cover tunnels.

Bored Tunnel

3. Immersed tunnels:

Immersed tunnels are built by prefabricating tunnel segments on land and then floating them out to their final location. Once the segments are in place, they are lowered to the sea or river bed and joined together. Immersed tunnels are commonly used for building tunnels under rivers or bays.

Immersed Tunnel

4. Shield tunnels:

Shield tunnels are similar to bored tunnels, but they use a different type of machine called a shield. Shield tunnels are used for building tunnels in soft soil or sand, where boring machines would not work well. The shield machine uses hydraulic jacks to push against the tunnel walls and push the machine forward. As the machine moves forward, the walls are supported by precast concrete segments that are placed behind the machine.

5. Cavern tunnels:

Cavern tunnels are built by excavating large underground chambers, either naturally or artificially. Cavern tunnels are often used for storage or for underground power plants. Caverns can be excavated in hard rock or in softer materials such as salt domes or limestone caves.

Cavern Tunnel

6. Service tunnels:

Service tunnels are used for utility purposes, such as carrying water, sewage, or electrical cables. These tunnels are typically small and are often dug by hand, using shovels and other hand tools. Service tunnels are essential for maintaining and repairing infrastructure without disrupting normal traffic flow.

 

In conclusion, tunnels are a vital part of modern infrastructure, and they come in many different shapes and sizes. From cut-and-cover tunnels to service tunnels, each type of tunnel serves a unique purpose and requires specialized construction techniques. Tunnels are essential for improving transportation, providing energy, and supporting urban growth.

 

Suggested Read:

Concrete Tunnel Design and Calculation Spreadsheet Based on AASHTO and ACI

Tunnel Boring Machine Types

Concrete Tunnel Design Spreadsheet

Tunnel Typical Section Autocad Free Drawing

 

 

The Main Types of Traffic Barriers for Roads and Highways

The Main Types of Traffic Barriers for Roads and Highways

 

Road barriers are a critical component of transportation infrastructure. They are important to prevent vehicles from crossing over into oncoming traffic, to protect pedestrians and cyclists, and to delineate lanes on highways and roads. In this article, we will explore the different types of road barriers and their uses, as well as their benefits and potential drawbacks.

Types of Road Barriers:

There are several types of road barriers, each designed for a specific purpose. The most common types of road barriers include:

  • Steel highway barriers

Metal road barriers are becoming more popular as an option for roadwork crews working in the road corridor. This is because some models on the market feature one of the highest possible MASH ratings, being rated at TL-4.

This rating refers to the ability of the roadside safety barriers to deflect and control out of control vehicles, and generally the higher the MASH rating, the faster the speed zone it can be used in. This makes steel barriers a good choice for the fastest road speeds such as those found on freeways, motorways and highways.

Steel road barriers are generally sold in 6m long units which are easy to install using a T shaped connecting pin.

  • Plastic jersey barriers

Barriers made from polypropylene or blow moulded plastic are generally only suitable for lower speed areas. This limits their use on highways or faster speed roads, as many of these barricades are rated to a maximum of 70km/hr. This means they are probably not the best choice for highway use, as speeds would generally be well above this level.

However, you might see plastic barriers used on worksites at the side of a highway: they are a great all rounder and can be used to create temporary worksite carparks and walkways.

They are also used to barricade items such as power poles or electrical boxes so that worksite plant such as excavators does not accidentally bump into these obstacles.

  • Concrete barriers

These roadside safety barriers are one of the most common to be used around temporary road work, new road construction and infrastructure sites. Also known as jersey barriers, these barriers are TL-3 rated making them suitable for use on most Australian highways.

Jersey barriers are constructed with a steel bar running through the middle of the concrete, giving it extra strength and rigidity and helping to link all of the barriers together in a long line.

 

 

Uses of Road Barriers:

Road barriers are used for a variety of purposes, including:

  1. Separating opposing lanes of traffic: Jersey barriers and cable barriers  separate opposing lanes of traffic on highways and prevent head-on collisions.
  2. Protecting pedestrians and cyclists: Bollards  protect pedestrians and cyclists from vehicles by creating a physical barrier between them.
  3. Channelizing traffic: Barriers are often used to create lanes of traffic and prevent vehicles from veering into other lanes.
  4. Protecting work zones: Water-filled barriers are often used in construction zones to separate traffic from work areas, keeping workers safe.

Disadvantages of Road Barriers:

 

The benefits of road barriers are numerous. They can help prevent accidents by separating opposing lanes of traffic and protecting pedestrians and cyclists from vehicles. Road barriers can also reduce the severity of accidents by absorbing the impact of a collision, potentially saving lives.

Another benefit of road barriers is that they can be cost-effective. While the initial cost of installing barriers can be high, they can save money in the long run by reducing the cost of accidents and the associated medical bills, property damage, and legal fees.

Disadvantages of Road Barriers:

 

Despite their benefits, road barriers can have drawbacks. They can obstruct the view of drivers, making it difficult for them to see oncoming traffic or pedestrians. Additionally, road barriers can limit the ability of emergency vehicles to respond to accidents.

Road barriers can also create traffic congestion, particularly in urban areas limited with limited spaces. They can make it difficult for vehicles to merge or change lanes, leading to backups and delays.

Conclusion:

Road barriers are a crucial component of transportation infrastructure, providing safety and protection for motorists, pedestrians, and cyclists. There are several types of road barriers, each designed for a specific purpose. They can offer numerous benefits, including preventing accidents, reducing the severity of collisions, and saving money in the long run.

However, road barriers can also have drawbacks, including obstructing views, limiting emergency vehicle access, and creating traffic congestion. As with any transportation infrastructure, it is essential to weigh the benefits and drawbacks of road barriers carefully. It is always a good practice to consider their use on a case-by-case basis.

The Best Software For LIDAR Classification

The Best Software For LIDAR Classification

 

 

LiDAR, which stands for Light Detection and Ranging, is a remote sensing technology that uses laser pulses to measure distances and create 3D models of surfaces. LiDAR data can be used for a variety of applications, including urban planning, forest management, and topographic mapping. One of the most important steps in processing LiDAR data is classification, which involves identifying and labeling different types of objects and terrain features in the LiDAR point cloud.

There are several software packages available for LiDAR classification, each with its own unique features and benefits.

1. LAStools:

 

LAStools is a popular software package for LiDAR processing and classification. It includes a suite of tools for filtering, quality control, and classification of LiDAR data. LAStools can classify LiDAR data into ground, non-ground, buildings, vegetation, and other features. It also includes tools for point cloud thinning, which can significantly reduce processing times.

2. TerraScan:

 

TerraScan is another powerful software package for LiDAR classification. It includes a range of tools for point cloud management, filtering, and classification. TerraScan can classify LiDAR data into ground, buildings, vegetation, and other features, and can also perform advanced classification tasks such as building footprint extraction and power line detection. TerraScan is widely used in the forestry, transportation, and utility industries.

 

3. ArcGIS:

 

ArcGIS is a popular GIS software package that includes tools for LiDAR data processing and classification. It can classify LiDAR data into ground, vegetation, buildings, and other features, and can also perform advanced classification tasks such as tree species identification and canopy height modeling. This software is widely used in the urban planning, forestry, and environmental management industries.

 

4.CloudCompare:

 

CloudCompare is an open-source software package for LiDAR data processing and classification. It includes a range of tools for point cloud filtering, registration, and classification. CloudCompare can classify LiDAR data into ground, non-ground, buildings, vegetation, and other features. It is widely used in the surveying, archaeology, and geology industries.

5.TopoDOT:

 

TopoDOT is a software package for LiDAR processing and classification that is specifically designed for the transportation industry. It includes tools for point cloud management, filtering, and classification, as well as advanced features such as automated roadway extraction and sign detection. TopoDOT is widely used in the transportation industry for highway and rail planning, design, and maintenance.

6.GlobalMapper:

 

One of the key features of Global Mapper’s lidar classification tool is the ability to distinguish between ground and non-ground points. This is an essential step in many lidar applications, as it enables accurate terrain modeling and surface analysis. Global Mapper offers several algorithms for ground point classification, including the progressive morphological filter (PMF) and the triangulated irregular network (TIN) method.

 

In conclusion, LiDAR classification is an essential step in processing LiDAR data for a variety of applications. There are several software packages available for LiDAR classification, each with its own unique features and benefits. LAStools, TerraScan, ArcGIS, CloudCompare, and TopoDOT are some of the most popular software packages for LiDAR classification, widely used in different industries for different purposes. It is important to select the appropriate software package based on the specific requirements of the project and the industry.

 

How to Determine Which Conveyor System is Best for Your Operations

How to Determine Which Conveyor System is Best for Your Operations

 

Conveyor systems are widely used because they save companies time, money, and resources that would otherwise be spent moving materials. There are many different types of conveyor systems that can be used in a variety of applications. But, how do you know which one’s best for your company?

What is a conveyor system?

Conveyor systems make it easier to move objects from one place to another. Their design allows you to move materials too heavy or bulky to carry by hand effectively. These pieces of automated equipment can be seen in a variety of places such as airports, scrap yards, large factories, and even grocery stores.

Commonly used types of conveyor systems

With so many different types of conveyor systems, it can be difficult to choose one that best suits your unique operation. However, once you have a basic understanding of the main types of conveyor systems, the choice will be much easier.

 

Let’s take a look at some of the kinds of conveyor solutions and the different purposes each one serves:

Belt Conveyor

Belt conveyors consist of a wide belt that fits over a flat surface or rollers to move items from point A to point B. These systems are stable, keeping the items in position, so they are unlikely to jostle and fall. They also keep the items transported at a consistent pace. That way, you don’t have to worry about your materials bumping into one another or becoming unorganized during transport.

Chute Conveyor

A chute conveyor is the most basic example of a gravity-operated system. They are used in bulk-handling applications to gather items into shipping areas or convey items between floors. Chute systems can even be used to easily load belt conveyors or transfer materials from one moving belt to another.

Gravity Roll Conveyor

Gravity roll conveyors allow materials to move on the rollers using momentum rather than a motor. Warehouse facilities often use these rollers to move boxes, totes, and cartons because they are a cheap and simple solution compared to other conveyor systems. Depending on the model you choose, gravity rollers can hold anywhere between 95 to 3000 pounds per roller.

Bucket Conveyor

Bucket conveyors are used for transporting bulk and small size materials vertically. They’re made of a loop of buckets that stay level when moving from horizontal to vertical, preventing the materials from spilling along the way. These systems are often utilized in food, pharmaceutical, cosmetics, agricultural, and chemical applications.

Ball Transfer Conveyor

Ball transfer tables are used in packing and assembly operations where items need to be moved or rotated in more than one direction. It’s composed of load-bearing spherical balls mounted in a casing that restricts the ball from moving. When assembled into a table, they work together to transfer products to and from machines and conveyor systems efficiently.

Chain Conveyor

Manufacturing and warehousing companies utilize chain conveyors to move products down an assembly line or around the facility. They are equipped to transport heavy unit loads that don’t efficiently move on rollers, such as wrong-way pallets, automobile frames, and racks. Since chain systems easily integrate into CDLR and chain transfers systems, implementing these conveyors also adds versatility to production lines.

Trolley Conveyor

A trolley conveyor is a system of trolleys supported by an overhead track that’s connected to a chain or cable that propels the trolleys. You can use these continuously operating devices in various applications. Facilities primarily use them to move packaged and piece materials long distances around a shop since the system doesn’t require floor space.

Magnetic Conveyor

Magnetic conveyors are one of the types of conveyor belt systems. They are created by placing permanent magnets in the bed of a regular conveyor. These systems can hold ferrous or iron-containing parts fast to the belt, making them suited for elevation changes. You can also use them upside-down since the strength and size of the magnets are designed to fit each application.

Key conveyor system applications

Manufacturers and warehouse facilities typically include conveyors for pick-and-place, assembling, dispensing, and palletizing in their production practices. Due to the versatility of the different types of conveyor systems, companies can use them to suit their unique operations, making them a one-size-fits-all solution.

Some examples of commonly used applications for conveyors include:

Assembly lines

Conveyor systems are an excellent way to speed up your product assembly operations. The item automatically moves along the machinery to each station as pieces are added until the finished product is created.

Packing stations

Product-handling conveyors can be used to create packaging and processing stations. Employees or pick-and-place robots can grab items from the moving belts and package them into containers without leaving their station.

Inspection systems

You can use conveyor systems to automate various inspection processes, from ensuring a product works to determining if it’s the right size. When defective products are found, a conveyor can move them into a separate location from products that pass inspection.

Do you need a conveyor system for your facility?

Conveyor systems have become more widely used as there’s an increased demand for transporting goods as quickly as possible. Cutting down the time it takes to transport materials means that your business can fulfill customer orders more efficiently.

 

Here are some of the signs that your facility needs to implement a conveyor system:

Limited transportation ability

The different types of conveyor systems offer unlimited opportunities for facilities to move their products from one place to another. This allows you to optimize your operations and speed up time to fulfillment, ensuring that your customers get their orders on time.

Need greater protection of goods

Being able to choose the mode of transportation can save you a great deal by preventing lost and damaged products. When goods are moved around a warehouse by busy employees, there are likely to be a few accidents, but everything automatically transitions smoothly with conveyors.

Too many valuable resources are being used to move materials

Moving material by hand not only creates a security risk, but it’s also a waste of valuable resources. If you find that you don’t have enough employees to run your operation, you should look into implementing conveyor systems rather than hiring more people.

What is Pumped Concrete? Advantages of Pumped Concrete

What is Pumped Concrete? Advantages of Pumped Concrete

 

 

What is Pumped Concrete:

 

The method in which the fresh concrete is pumped to the area where the concreting work to be done is called as pumped concrete. For small work, concreting can manually be done, but for large scale work, concreting is efficiently done by pumping.

Concrete pumps are generally mounted on a truck or on a trailer. Pumps can be operated by electric power or diesel. Pipeline pumping system has a diameter between 100mm to 180mm. Diameter size of 125mm is must probably adopted for pumping the concrete.

Modern and advanced handy or portable concrete pumps have more power, high capacity and absolutely reliable hydraulic system and these pumps can take the fresh concrete to a height near about 600 m and also can take the concrete in horizontal distance near about 200 m.

Pumps have fully hydraulic, compact and dirt resistance control system. Hydraulic pump is output regulated and hence require less power utilization at an ideal speed and pressure.

Taper and a clamping device is provided to the outlet portion of the pump so as to connect the pipeline. The outlet portion is easy to clean and also has a simple side swing. The agitator maintains the concrete in an agitated form in between two batches of concrete fed into the hopper.

The concrete pump unit is mounted one the chassis of a tuck and drive of the hydraulic pump is driven from the engine of truck directly. Water pump is joined to the water tank and it is driven hydraulically.

The pump capacity is in m3/hr and it depends on a distance of pumping the concrete, diameter of delivery line and the maximum line pressure.

Concrete pumping capacity depends upon the following factors:

  • Horizontal pipe length through which concrete can be pumped.
  • Vertical pipe length through which concrete can be pumped.
  • Number of bends in pipe line.
  • Diameter of delivery pipe line.
  • Length of flexible hose pipe.
  • Number of reducers in the pipe line.
  • Workability of concrete and its cohesiveness.
  • Type and size of aggregates used in the concrete.
  • Proportion of ingradients in the concrete.

 

Advantages of Pumped Concrete:

 

Following are the advantages of pumping the concrete for casting the various member of the structures:

  • Concrete can be moved horizontally as well as vertically at a time
  • It provides a good quality control.
  • Concreting by pumping is the most effective and sensitive method because any variation in concrete mix can be easily rectified at the pumping point by observing the pumping pressures and hence there is a proper control on consistency and workability of concrete.
  • It refuses to handle any concrete which is unduly harsh, non-cohesive, inadequately mixed, improper consistency.
  • No wastage of concrete if casting work done by pumping, but there is more wastage of concrete if casting work is done manually.
  • Pumped concrete has high workability and good cohesion which provides good finish and ultimate strength.
  • By pumping system, concrete can be placed in inaccessible areas.
  • Mass concreting work can be carried out in a limited time with high speed without cold joints.
  • For high rise building, pumped concrete method is best suitable, economical and faster.
  • Pipeline for delivery of the concrete require a very less space and can be easily extended to the desired height and can be easily removed.
  • The total unit of pumped concrete helps to complete the contacts within the prescribed time given in agreement. It also reduces the site-overheads.

What is Total Station? Principles and fundamentals – Advantages and Disadvantages

What is Total Station? Principles and fundamentals – Advantages and Disadvantages

 

Total station is used for computing slant distances, horizontal and vertical angles, elevations in topographic and geodetic works, tacheometric surveys, etc. The total station is a pre-eminent contribution to modern surveying and hence the equipment is designed for speed, range, and accuracy. They are a combination of Theodolite and Electronic Distance measurement (EDM). This enables computing the vertical, horizontal as well as slope measurements.

They acts as a substitute for theodolite, EDM, Data collector, and a Microprocessor. Moreover, they are lightweight and compact machines and perform like transit stadia and plane table alidades.

The integration of microprocessors helps in the data collection and measurement computation process. Further to that, the inbuilt software helps to generate the maps instantly.

Applications

Apart from taking the measurements, the total station helps in computing, interpreting, and documenting the data. Here is a list of activities that are computed, interpreted, and analyzed.

  • Horizontal angle
  • Vertical angle
  • Slope distance
  • Coordinate of point
  • Missing line measurement
  • Area calculation
  • Contour level

Principle of Total station

The total station consists of a built-in emitter, capable of emitting microwaves and infrared signals. The wavelength of these emitted waves helps in calculating the distance between the points.
Distance = velocity * time 

Here the distance is calculated by multiplying the time taken to cover a certain distance by the velocity. However, Triangulation and trigonometry methods are adopted for computing the angles and determining the coordinates.

Total Station Components

The Equipment is composed of different parts. Below listed are the major components.

 

Components of total station
  • Handle
  • Handle securing screw
  • Data input/output terminal (Remove handle to view)
  • Instrument height mark
  • Battery cover
  • Operation panel
  • Tribrach clamp
  • Baseplate
  • Levelling foot screw
  • Circular level adjusting screws
  • Circular level
  • Display
  • Prism and prism pole
  • Objective lens
  • Tubular compass slot
  • The optical plummet focusing ring
  • Optical plummet reticle cover
  • Optical plummet eyepiece
  • Horizontal clamp
  • A horizontal fine motion screw
  • Data input/output connector
  • External power source connector
  • Plate level
  • Plate level adjusting screw
  • Vertical clamp
  • A vertical fine motion screw
  • Telescope eyepiece
  • Telescope focusing ring
  • Peep sight
  • Instrument centre mark

A tripod enables to affix the equipment onto the ground. A handle is available on the top of the equipment for holding it. There are a Data input and output terminal below the handle enabling the data transfer to the computer.
The total station comes with inbuilt software, an operation panel, keyboard, and a screen. The prism and prism poles helps in measuring distances.

Advantages of Total station

There are a lot of advantages of total station as follows.

  • High precision and accuracy.
  • Requires limited manpower
  • Perform quick field work
  • Reduction in manual errors.
  • Correction for temperature, pressure etc and digitally rectified.
  • Storage and interpretation of data is easy
  • Time consumed is less.
  • Inbuilt GIS software helps in instant map creation
  • Assists in local languages.

Disadvantages of Total station

  • The cost of the instrument is high.
  • Need high skilled surveyor with AutoCAD knowledge and professional training.
  • Checking errors during the operation is impossible.
  • Low battery life.

What Is Anchor Block Slope Stabilisation?

 

What Is Anchor Block Slope Stabilisation?

 

Anchor block slope stabilization is a technique that stabilizes slopes or existing retaining walls using anchored reaction blocks. The block layout pattern is typically in rows across the slope or wall. The finished anchored reaction blocks resist the movement of the retained soil or wall.

Anchors are slope stabilization and support elements that transfer tension loads using high-strength steel bars or steel strand tendons. Micropile Slide Stabilization System (MS³) is a slope stability technique that utilizes an array of micropiles sometimes in combination with anchors. The micropiles act in tension and compression to effectively create an integral, stabilized ground reinforcement system to resist sliding forces in the slope.

Advantages

  • Cost-saving solution for landslide repair and slope stability control
  • Can be designed for permanent or temporary support
  • Crane-mounted equipment can reach even the most difficult access slopes

 

 

https://www.theengineeringcommunity.org/wp-content/uploads/2022/01/Slope-stabilization-Anchor-block-slope-stabilization-.mp4?_=1

The Common Types of Plastering

The Common Types of Plastering

 

Introduction

Plastering is the process of covering the walls with plaster. The main purpose of doing plastering is to provide a smooth finishing surface and for avoiding deterioration of the walls.

Plaster is a plastic material that is a mixture of cement, sand with water. A good plaster should not show any volume change after drying and should not develop cracks. It also helps in making the structure weather resistant and durable. Plastering can be done on external as well as internal walls.

The choice of ratio of cement mortar for plastering can be chosen on the basis of requirement. In this article, we will discuss the various types of plastering in a building.

 

Types of Plastering

There are different types of plastering used in construction:

  • Cement plastering
  • Lime plastering
  • Mud plastering
  • Stucco plastering
  • Gypsum plastering

 

1. Cement plastering

Cement plastering is a type of plastering consisting of a mixture of portland cement, sand and water in appropriate proportion. The minimum thickness of cement plaster should be 10 mm. For brick walls, thickness plastering is between 15 mm to 20 mm.

Also, Plastering is applicable for both internal and external walls. Cement plastering is mostly suitable for damp conditions. It acts as a protective layer and avoids corrosion. For RCC surfaces, 1:3 or 1:4 cement plaster is applicable. For external walls 1:5 or 1:8 cement plaster is applicable. After plastering, to avoid the developing of cracks, curing is done.

2. Lime plastering

Lime plaster consists of lime, sand and water. Since it consists of lime it is called lime plaster. Non-hydraulic hydrated lime is used in Lime plastering. It is one of the oldest plastering methods. When comparing with cement plaster, lime plaster has low binding capacity and delay in setting. The ratio of lime and sand for this plaster is 1:3 to 1:4.

3. Mud plastering

Mud plastering is one of the cheapest types of plastering. Another name of mud plaster is earthen plaster. Before plastering, eliminate dust and scrap the surface for making it rough. Generally, mud plastering is done in two coats. The thickness of the first coat is 18 mm and that of the second coat should be 6 to 7 mm. This plastering is less toxic and eco-friendly.

4. Stucco plastering

Stucco plastering is a type of plastering that gives an aesthetic appearance. It consists of aggregates, binders and water. It is applicable for both internal and external walls. There are two types of stucco plaster, Modern and traditional plaster. Usually, three coats of stucco plastering are applied they are scratch coat, fine coat and finishing coat. The thickness of stucco plaster should be 25 mm.

5. Gypsum plastering

Gypsum plastering is a type of plastering where gypsum replaces with cement. This plastering provides good finishing for the surface. Gypsum is a binding material. The thickness of gypsum plastering can be 6 to 20 mm. An important characteristic of gypsum is they do not shrink during drying. Hence we can avoid the development of cracks. Gypsum plaster does not need curing. Also, it is white in colour, So it gives a good aesthetic appearance.

 

What are Deep Foundation? The Common Types of Deep Foundation

What are Deep Foundation? The Common Types of Deep Foundation

 

1. What are Deep Foundations?

A deep foundation is needed to carry loads at depth or for functional reasons from a structure through weak compressible soils or fills on to stronger and less compressible soils or rocks.

Deep foundations under the finished ground surface are founded too deeply for their base bearing ability to be affected by surface conditions, generally at depths > 3 m below the finished ground level.

When unsuitable soils are present near the surface, the deep foundation may be used to transfer the load to a deeper, more capable strata at depth.

2. Types of Deep Foundation

The types of deep foundations in general use are as follows:

  • Basements
  • Buoyancy rafts (hollow box foundations)
  • Caissons
  • Cylinders
  • Shaft foundations
  • Pile foundations

 

a. Basement foundation

They are hollow substructures built to provide space below ground level for the work or storage. The structural design is driven by its practical needs rather than by considerations of the most effective method of resisting external earth and hydrostatic pressures. In open excavations, they are set up in place.

 

b.Buoyancy Rafts (Hollow Box Foundations)

Buoyancy rafts or hollow box foundations also known as the floating foundations is a type of deep foundation is used in building construction on soft and weak soils.

They are designed to provide a buoyant or semi-buoyant substructure underneath which reduces net loading to the desired low intensity on the soil. Buoyancy rafts can be constructed to be sunk as caissons, and can also be installed in open excavations.

Buoyancy rafts are more expensive than traditional forms of foundations. For that reason, their use is usually restricted to sites that are on silts, soft sands and other alluvial deposits that are very deep, or where loads can be kept concentric. Schemes requiring underground tanks or where it’s economical to incorporate deep basements into the design are common.

c. Caissons Foundations

A caisson is a sort of foundation of the state of the hollow prismatic box, which is worked over the ground level and afterward sunk to the necessary depth as a solitary unit. It is a watertight chamber utilized for establishing foundations submerged as in rivers, lakes, harbors, etc. The caissons are of three types:

  • Open Caissons: Open caissons are of hollow chambers, open both at the top and the bottom. The lower part of the caisson has a bleeding edge. The caisson is sunk into place by eliminating the soil from within the shaft until the bearing layer is reached. Well foundations are special type of open caissons used in India.
  • Pneumatic Caissons: Pneumatic caissons are closed at the top but open at the bottom. A pneumatic caisson has a working camber at its bottom in which compressed air is maintained at the required pressure to prevent entry of water into the chamber. So, these type of excavations are done in dry.
  • Floating Caissons: Floating caissons are open at the top but closed at the bottom. These caissons are developed ashore and afterward shipped to the site and floated to where these are to be finally installed. These are sunk at that spot by filling them with sand, ballast, water or concrete to an evened out bearing surface.

 

d. Cylinders

These foundations are placed when there is required to place only a single cylindrical unit.

e. Drilled Shaft foundations

These foundations are constructed by drilling a cylindrical hole within a deep excavation and subsequently placing concrete or another prefabricated load-bearing unit in it.

Their length and size can be easily tailored. Drilled shafts can be constructed near existing structures and under low overhead conditions, making them suitable for use in numerous seismic retrofit projects.

It may, however, be difficult to install them under certain conditions such as soils with boulders, soft soil, loose sand, and sand under water.

 

e. Pile foundations

Pile foundations are relatively long and slender members designed by driving preformed units to the desired foundation level, or by driving or drilling in tubes to the appropriate depth – tubes filled with concrete before or during withdrawal or by drilling unlined or wholly or partially lined boreholes filled with concrete after that.

 

 

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