The impact of environmental factors on foundation type selection for bridges over water is explored. The construction of foundations for bridges over water is a difficult and time-consuming task, and the designer will face numerous difficulties. Environmental conditions, rather than ground conditions, are the most important factor that may influence the design of bridges over water. This is in contrast to the design of bridge foundations on land, which is governed by ground conditions. As a result, it’s critical to comprehend the environmental factors that influence water bridge design and their impact on foundation kinds and construction procedures.
The Impact of Environmental Conditions on Bridge Foundations
The Impact of Environmental Conditions on Bridge Foundations The following are some of the environmental conditions that influence the types of overwater foundations and how they are built:Water depths and exposure Conditions Currents in the sea or rivers Collision of ships Earthquakes caused by floating Ice Ridge Foundations’ Exposure Conditions and Water Depths When a bridge is built in the open waters of a big bay crossing, it is frequently subjected to strong currents and winds. This active state has unfavourable consequences, such as the deterioration of unfinished structures and the limitation of the operation period of floating construction plants. This unfavourable circumstance stimulates the use of large prefabricated structural elements. Open well caissons and box caissons, for example. Floating and transporting caisson units to the bridge construction site is typical practise. They then proceeded to.
When the seawater is sufficiently deep for box caisson floatation, a box caisson can be used. The weather has a big impact on the transportation of the caisson box to the bridge building site, as well as the sinking and installation of the caisson pieces. As a result, it is vital to factor in the possibility of construction delays due to inclement weather. The open well caisson is appropriate for shallow water in which the shallow draught bottom portion is floated and brought to the building site and submerged by removing the dirt from the open wells while the walls are gradually elevated. It’s worth noting that the open well caisson construction procedure is more susceptible to the effects of weather than the closed well caisson construction method.
Effect of Sea or River
A drag force created by a sea or river current may be applied to pilings or piers. In areas where the soil is vulnerable to erosion at sea level, this force forms scour holes.The presence of these holes surrounding cofferdams is undesirable because transient conditions such as partially driven sheet piles produce cyclic water movement in this area. While sheet piles or bearing heaps are being installed, the current drag force is likely to cause problems. This is because high-velocity force oscillates, causing damage to the pile prior to the installation of pile caps or interim grit to keep the pile from oscillating.
The Impact of a Ship Collision on the Foundation of a Bridge Ships that are out of control are likely to collide, potentially causing bridge pier failure. In some broad estuaries, a deep water channel can swing from one side to the other in a short period of time, putting practically all of the bridge’s piers at risk.The former Sunshine Skyway Bridge, which collapsed in 1980 after a vessel collided with one of the bridge’s piers, is a true illustration of ship collision danger. The Old Sunshine Skyway Bridge has collapsed. The Old Sunshine Skyway Bridge Collapse In 1980, the ancient Sunshine Skyway Bridge collapsed. In 1980, the old Sunshine Skyway Bridge collapsed owing to a collision with a train.
collision of a vessel with one of the piers of the bridge
As a result, it is vital to take the required precautions to avoid ship collisions with piers. The total cost of foundation construction would undoubtedly rise as a result of these precautions. Providing an artificial island around the pier to prohibit vessels from colliding with the bridge pier is one example of a measure against ship collision. For piers in shallow water, this protection method should be considered.Surrounding Bridge Piers with an Artificial Island to Protect the Pier from Ship Collisions : Artificial islands protect the piers of the Penang Island Bridge from ship collisions.Details of the Man-Made Island that Surrounds the Bridge Piers Details of the Artificial Island Surrounding Bridge Piers to Prevent Ship Collisions The amount of stones needed for wave protection if artificial islands are built in deep water.
Fender piles, which are typically joined by huge ring beams, are another form of protection. The ring beams should be set back from the pier to allow for pier displacement while absorbing the kinetic energy of a moving vessel and bringing it to a complete halt. As a precaution, short piles are placed around piers: The Sunshine Skyway Bridge has short piles surrounding the piers as a safety precaution against ship collisions.Defending the Pier Bridge from Ship Collisions: Pier Bridge Protection against Ship Collisions Floating Ice’s Impact on Bridge Foundations The impact of a floating ice sheet on the bridge pier is similar to the impact of a colliding ship on the bridge pier. As a result, their designs are identical to one another. However, the former poses an additional risk.
prevent ridge pressure formation
When pressure ridges occur, the direction of build-up pressure is transversal to the bridge pier or vertical. Single pier bridges are preferred over group piles because single piles change the direction of ice floes and avoid the establishment of ridge pressure. The application of narrow piers with a substantial base is the ideal kind of bridge foundation in locations prone to floating ice for gravity base structures. This is because the latter provides resistance to sliding and overturning pressures, whereas the former provides little resistance to floating ice sheet forces. Furthermore, if piles are required because of ground conditions, a ring of closely spaced skirt piles should be erected around the group.
Finally, if the water flow is parallel to the river bank, introducing cut waters to the piles would offer an acceptable response to the floating ice forces. This is due to the fact that cutwaters would cut and break ice floes, avoiding the impact and pressure of floating ice sheets. Earthquakes inflict significant damage to bridge piers, particularly in deep water, since the force exerted on the bridge superstructure is combined with the load on the pier, resulting in a significant overturning moment at the pier’s base. The mass of water replaced by the pier is to be added to the pier’s mass.
Earthquake Damage to Bridge Foundations
In deep water, the eccentric load borne by the pier is critical, making a narrow pier with a hefty base an attractive alternative. Because seismic forces have no particular direction and can occur in any direction, it is recommended that a circular column be used. The liquefaction of loose to medium dense soil caused by ground shaking is another issue. This problem could be solved by constructing pile foundations to densify the soil to the point where piers can be supported safely. Using particle size distribution and in situ density, the depth of liquefaction can be calculated.Finally, liquefaction could trigger a tsunami or develop undersea flow slides, resulting in a horizontal force at the pier’s base.
The movement of expansive and highly flexible soils beneath different portions of the foundation footings is the most common cause of foundation failure. Shrinkage, which causes settlement, or expansion, which causes heave, are two types of soil movement.
The nature and bed conditions of river or stream.
Permanence. It’s essential for foundations to be placed in an area.
Foundation base should be strong enough to reduce the unequal settlement of soil.
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