We engineers have the onus of building a new India for future generations but are we doing justice to our education? Today, many of the bridges built in India are rested on pile foundation. The life of any structure is said to be 100 years but in absence of following the laid down rules, the life will not be 100 years and unprecedented structure failure could be catastrophic.
Pile foundation is a method used where the bearing capacity of the soil is not meeting the required load carrying capacity. Pile foundation is a means of transferring the load of the structure to the strata where desired bearing capacity is encountered. For doing so, the designed diameter bore is made using various piling techniques upto the depth where firm strata , per design, is encountered. For the safety and long life of structure, it is very much desirous that pile engineer ensure the removal of the loose material from the bore and pile should be rested on firm strata.
Nowadays, the less skilled piling contractors, who are not well versed with the functionality of the pile and who are more interested in earning big money by whichever way possible, are using Truck mounted rig (TMR) for pile foundation. TMR is basically an equipment used for boring water bores for potable water. TMR is not meant for drilling bores for the purpose of pile foundation as TMR is not capable of removing loose material from the bore. Thus, usage of TMR results in laying the foundation of the structure on loose soil/strata.
As per CPWD DSR, usage of Truck mounted rig (TMR) is prohibited, but in absence of proper know how of the pile foundation and its function, today TMR’s are ubiquitously used for building pile foundation. They are used in many of the bridges constructed under the guidance of NHAI and other government agencies. Thus, in order to give a structure with long life to the nation, the onus lies on all the engineers of the country to ensure that the pile foundation is done in the most appropriate manner as to satisfy the requirement of the pile foundation.
Thus, TMR is not the substitute of Direct mud circulation (DMC) or rotary hydraulic rig method of Pile foundation.