River bridge foundation 1

[victor923]

I am designing a river bridge and have a few questions on it
I am designing to use a bankseat pile foundation and the ground is made of soft clay

1. If there is rapid variation of river level, will the water table on the retain side be higher than the river level so a higher water pressure will be act on the abutment?

2. In considering the drained and undrained condition, normally drained condition is considered as critical. What calculation should be done with drained condition? Moreover, live load and braking force are considered as undrained loading. how to apply them into an drained condition?

THANKS

 

[cvg]

answer to question 1) is yes, rapid drawdown will cause the bank to be saturated after the flood recedes

I will let others answer question 2)

 

[VoyageofDiscovery]

Typically the piles are axially loaded so live load and braking go to the base of pile on bedrock. Are you seating your piles on hard clay or using friction piles?

 

[ishvaaag]

Not precisely answering your question 2, but a reminder: since live load and braking will concurr in whatever the state expected in the soil, you will need to provide a path of loads to firm foundation in whatever the case.