Caisson Foundation

Caisson Foundation

WHAT IS CAISSONS?

• It’s a prefabricated hollow box or cylinder

• It is sunk into the ground to some desired depth and then filled with concrete thus forming a foundation.

• Most often used in the construction of bridge piers & other structures that require foundation beneath rivers & other bodies of water

• This is because caissons can be floated to the job site and sunk into place

• Basically it is similar in form to pile  foundation but installed using different way

• used when soil of adequate bearing strength is found below surface layers of weak materials such as fill or peat

• It’s a form of deep foundation which are

• constructed above ground level, then sunk to  the required level by excavating or dredging material from within the caisson

TYPES OF CAISSONS

• Box Caissons

• Excavated Caissons

• Floating Caissons

• Open Caissons

• Pneumatic Caissons

ADVANTAGES

• Economics

• Minimizes pile cap needs

• Slightly less noise and reduced vibrations

• Easily adaptable to varying site conditions

DISADVANTAGES

• Extremely sensitive to construction procedures

• Not good for contaminated sites

THE PROCESS: BUILDING A CAISSON

• After some initial form work and concrete pours, the cutting edge is floated to the breakwater by towboat and fastened to the caisson guide. Concrete is placed (poured) into steel forms built up along the perimeter of the box. With every concrete placement, the box becomes heavier and sinks into the water along the caisson guide.

• Forms are also built inside the box around the air domes and concrete is placed in between. The resulting open tubes above the air domes are called dredge wells

• When the caisson finally touches the river bottom, the air domes are removed and earth is excavated through the long dredge well tubes, as shown in the animation below. The caisson sinks into the river bottom. Excavation continues until the caisson sinks to its predetermined depth

• As a final step, concrete is placed (poured) into the bottom 30 feet of the hollow dredge wells and the tops are sealed.

Risk That Could Derail Projects

Identifying Risk Connections That Could Derail Projects  

The World Economic Forum’s (WEF) annual Global Risk Report includes graphical representations of how the critical risks facing the world are interconnected. Some of the risks identified by the WEF report—prolonged infrastructure neglect, major systemic financial failure and pervasive entrenched corruption—raise red flags for any business involved in major infrastructure projects around the world.

Most project managers track costs and schedules, but risk is the all-important third dimension and can be hard to identify, record and analyze. Unlike the WEF, which includes business leaders, politicians and academics, construction companies don’t have the luxury of calling on a panel of global experts to identify risks. But, they are well-equipped with their own staff, partners and suppliers closest to the real risks and the opportunities affecting the business. The difficulty has been to develop a corporate culture in which staff call out the risks faced and can use a simple mechanism to easily record them. Now that technology is available to aid the recording process, management can drive the cultural change needed. 

Most important for a project with a fixed deadline, having the overall picture meant risks could be mitigated at the most appropriate and cost-effective point. Without such an approach, management would not know to support the decisions and promises being made, and different project team members might duplicate mitigation efforts, leading to unnecessary cost overruns. 

The other benefit of a single risk repository is management can visualize how risks are interconnected. The latest analysis tools can produce representations of the “risk universe” faced by the project or enterprise and show the associated “risk constellations” that are forming. As a result, management can see the cumulative effect of risks that might have been deemed as relatively unimportant at the individual project level. 

For example, every project might identify the lack of skilled resources as a risk. Bringing in temporary staff is a reasonable mitigation action if the risk only happens on a single project, but enough skilled people may not be available if it hits several projects simultaneously. 

new construction techo.

In general, there are four types of construction:

1. Residential Building construction
2. Industrial construction
3. Commercial Building construction
4. Heavy Civil construction   

   Design and build

   Main article: 

   

   

   Construction of the Phase-1
   This approach has become more common in recent years and involves the client contracting a single entity to both provide a design and to build that design. In some cases, the Design and Build (D & B) package can also include finding the site, arranging funding and applying for all necessary statutory consents.
   The owner produces a list of requirements for a project, giving an overall view of the project's goals. Several D&B contractors present different ideas about how to accomplish these goals. The owner selects the ideas he or she likes best and hires the appropriate contractor. Often, it is not just one contractor, but a consortium of several contractors working together. Once a contractor (or a consortium/consortia) has been hired, they begin building the first phase of the project. As they build phase 1, they design phase 2. This is in contrast to a design-bid-build contract, where the project is completely designed by the owner, then bid on, then completed.