Sinking Bridge

there are possibilities for repairing the pier. however, the cause of the original sinking may simply reoccur when the next flood comes.

scour around and under the foundation may well be the cause of the piers demise and may need addressing for a repair or for a new bridge. i am assuming that deep piles were not used as it would be unusual for the flood conditions to make a piled foundation fail in this way.

deep piles (to bedrock or other stiff soil layer) could be driven from a boat (sheet piles even) and a secondary foundation attached to the central pier to prevent further descent. the new piles could even be used to support the bridge directly.

this is quite speculative as the ground conditions are unknown. best get the geological report for when the bridge was built. it will enable you to get a better informed answer.

Hi

Raising is done in poker and not in bridge. or not?

Are the pylons still sinking?

What is the rock and soil formation like?

What is the size of road and traffic?

A temporary steel bridge should afford them time to rebuild properly.

Yeah - tell your guys to install a temporary bridge - such as a Bailey Bridge

http://www.baileybridge.com/

while they fix the damn thing properly

If you take a look at my referenced photo, you can see a Bailey Bridge sitting atop the damaged structure.

mmmmmmmmmmm - excellent point - I missed that on first glance.

So tell them to move the Bailey over and fix the damn thing.

www.mointaingrout.com

Talk to Bill he will refer you to Bill Brady, P.E.

It can be raised and the problem rectified so it will not happen again.

if this photo was taken during or two days after the flood, it is a rocky (boulder) river bed due to the color of the water. dark brown is the color of the water for the soil/clay river bed.

if the cause of sinking pier is due to scouring, this pier is resting on spread fooding not on piles. except if the penetration length of the piles is less than the minimum required. but i am much sure that this is a spread footing because it is a combination of sinking and tilting.

sinking piers can be repaired by jacking-off the girders and inserting structural steel section (wide flange or I-beams) at the pier where the girders rest. but in this case, this methodology is no longer applicable due to tilting of the pier.

lifting the pier and grouting with hydraulic cement underneath is possible but you need a bigger lifting machine (crane) and craneway is necessary due to the size & weight of the unit. you have to be sure that the hydraulic cement will not be eroded during grouting by diverting the flow of the water or constructiong a cofferdam or crib.

i will suggest that it is be better to remove the damaged pier and replace it by driving steel piles (H-beam) and construct a concrete pile cap where the top level is the same elevation of the existing piers. (elevated pile cap - bottom is no longer at the river bed). in this case, you only need 25T crane to do the job and the existing bridge can be utilized as craneway by installing additional supports.

i also suggest that you must provide gabion mattress around the other existing piers in order to avoid scouring. quarrying 100 meters or more from upstream and downstream of the bridge must be prohibited.

Another suggestion in using the URETEK METHOD. This is another way to raise the pylon. Refer the web and look for Uretek under alternative Underpinning.

Good Luck

URETEK method or lifting structures by injecting polymer is a very good application for restoring slabs such as road pavements, ground slabs etc. dead weight of the slab or pavement is very small compare to the dead weight of pylon. small pressure is needed in order to lift the slab compare to the pressure required to lift the pylon (you must create a pressure more than the total weight of the pylon in order to lift the structure). another advantage of the slab is the the adjacent ground surface is covered with concrete slab and bursting due to applied pressure will be eliminated.

for pylon: in order to eliminate side bursting, you have to covered the perimeter ground surface area of the pier with heavy load or encased the foundation with steel sheet piles so that pressure will be concentarted on the area covered by the foundation only. remember, the applied pressure is not only an upward force but also creates lateral force that may affect the adjacent structures.

saying the pylon was already lifted and the top surface is levelled and already with the required elevation, what will be your next solution if you found out that the lifted structure is not alligned with the others?

Yeah this looks like a scour problem undermining the foundation of a spread footing. You are going to need a new bridge and the current one is severely damaged, and the foundations are unstable. You could attempt to mud-jack the foundation, but the next major storm would scour under the grout and undermine the foundation again. Additionally the structural damage to the bridge deck and frame could be an issue. I kind of wonder why they have so many supports anyways. Many bridges have much wider spans between the supports, and deep foundation caissons for the span supports to prevent undermining from scour.

Let us get it straight.

Bridge did not sink--only the midstream pylon(poor design in the first place) did.

The Midstream pylon is now solidly where it should have been resting .

Now the Bridge is quite safe.Tell everybody THAT.

Psychologically everybody is scared.

Put Confidence back--like politicians try to -when Wall Street sinks.

Wait till dry season appears. One Sunday stop Traffic and jack up the Bridge structure(you can do it easily on the sunk pylon) and put correct Packings +shims.

Restoration Complete-Till many yers later again -maybe.

mm

Greetings, MUKULMAHANT,

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