Monday, July 3, 2017

Shoring System- Soldier Type -Cost effective earth retaining

In 2012, a client  reached me to get to a shoring solution for an excavation.

'Shoring' is a civil engineering technique to retain the earth in deep  excavation.

The Client requested a  cost effective solution to support   7 m of earth in a  deep excavation. I provided two options with cost comparison.
1. Driving  of steel sheet pile
2. Soldier piles. 

Option -2 was economical and technically feasible.  owing to existence of deep sandy layer in the sub soil profile , the driving of sheet piles  predicted to be difficult.

Chosen the sheet pile option, I  developed  an Excel spread sheet to calculate the driving depth of the steel H iron . Simultaneously I developed  a finite element model for the same using Stadd Pro.  

I was compelled develop my own techniques to determine the driving depth of H iron as literature on the FE modeling using general FE software was limited.

I did several modelling but did not get the exact bending moment shape as it should be. After several attempts of different methods, I was succeeded in getting correct shape of the bending moment diagram and was in a position to  decided the driving depth of the pile. I compared this results with the excel spread sheet calculation and the results were matched.

Sunday, March 5, 2017

Solutions for Differential Settlement in Structures

Providing  structural solutions for differential  settlement  is a challenge that face by many structural  Engineers during their career.

Generally ,allowable differential settlement is  20mm ,maximum, between two adjacent columns. This is based on the 75% of the maximum allowable cumulative settlement for  shallow foundations  of 25mm.

Below are few general solutions that widely used to cope the differential settlement problems;

11.)Provision of  thick /rigid raft foundation

22.) Provision of deep basement  to reduce the Net Bearing Pressures

33.) Adopt deep foundation solutions such as Piles

  4.) Pre Loading of lightly loaded Columns

55.)  Structural Isolation between differently loaded areas with a Joint