DEPARTMENT OF CIVIL ENGINEERING (GEOTECHNICAL DIVISION)GOVERNMENT COLLEGE OF TECHNOLOGYCOIMBATORE -641013

A REPORT ON VISIT TO PILE CONSTRUCTION AT DMRC KOCHI.ByM.E 1ST YEAR GEOTECHNICAL ENGINEERING STUDENTS

ACKNOWLEDGEMENT

At the very outset, we take pleasure in thanking our honourable Principal Dr.V.LAKSHMI PRABHA for incorporating such industrial visit as a part of our curriculum.We would like to render our heartfelt thanks to our Professor and Head, Dr.T.MEENAMBAL for providing us an opportunity to visit such an uncommon site.Next we would like to thank our Associate Professor Dr.P.D.ARUMAIRAJ who is always at our reach to support and guide us in all academic aspects.And we thank our Assistant Professor Mr.V.SATHEES KUMAR for providing us valuable information throughout the visit.We extend our sincere thanks to Project Director Mr.P.SRIRAM and engineers of KOCHI METRO PROJECT, KERALA for explaining clearly about the various technical aspects involved in the pile works of the Kochi Metro and we thank District Collector of Ernakulam M.G.RAJAMANICKAM who gave us an inspiring and motivating speech during the visit.

INTRODUCTIONEducation when adorned with experience becomes knowledge. Knowledge empowers a man to resolve what he sees. Institution and curriculum now a day delivers both education and experience. Someone said seeing is believing and also feeling is more than believing.On 27.02.2014 & 28.02.2014, we saw and felt pile coming up at KOCHI METRO, KERALA. In the following report we share our experience with the pile we felt at the site.

SITE SEEN DURING THE VISIT

Site 1- KOCHIN METRO YARDRising of ground level.Constructing platform for the subway Box Jacking. Site 2- KOCHI METRO PIER CONSTRUCTION Auger Boring. Cast in-situ pile construction. Pile cap & pier construction Site 3- MAKING OF PRESTRESSED GIRDERS Prestressing of girders. Pier cap making

LOCATION OF SITEThe site (Kochi Metro Yard) is located near Choornikkara, Aluva, Kerala. The co-ordinates are 10.0715359 N, 76.3407343 E.FIG.1 SITE LOCATION OF METRO YARD

Fig.2 Box Jacking platform for the subway

CONSTRUCTION DETAILS OF KOCHI METRO YARD The substrata consist of laterite soil with water table at the surface. It has been proposed to fill the soil to overcome the low bearing capacity and settlements which may be differential. The hydraulic engineer recommended that the site should be filled by coarse grained gravel upto 3.75 m from the initial level based on the 100 years rainfall data and 95 % of field density must be achieved. They had adopted underreamed piles for the piers of metro at metro yard because frictionless soil lies under. Standard gauge rail is to be adopted. (4 feet 8 inches).

Fig.3 PROJECT DIRECTOR & SAFETY ENGINEER EXPLAINING THE PROJECT AND SAFETY PRECAUTIONS

Fig.4 SITE SEEING OF KOCHI METRO YARD

Fig.5 AUGER BORING FOR THE BORED IN-SITU PILE

LOCATION 2 (KOCHI METRO PILE CONSTRUCTION)

The site is located near Kalamassery , Ernakulam, Kerala. The co-ordinates are 10.05393 N, 76.3213403E. The points of boring are located using total station and temporary bench marks Auger boring was used to reach the hard strata. The auger can excavate the soil to a depth 2m in 10 minutes. They used cast in-situ pile of diameter 1.2 m. A group of 4 piles takes load from the pier. While constructing the pile, they checked the quality of work by the cross hole sonic test randomly. We have seen the sequence of pier construction works in order: Starting from pile, pile cap reinforcements, casting of pile cap concrete, reinforcement details of pier and casting. All the above mentioned works are done with sophisticated equipment using advanced methods.

Fig.6 SITE LOCATION OF PILE AND PIER CONSTRUCTION SEEN

Fig.7 PILE DRIVING EQUIPMENTS AND WITH WORKING EXPLANATION

Fig.8 REINFORCEMENT DETAILS FOR PILE AND PIER Fig.9 PILE CAP REINFORCEMENT

Fig.10 REINFORCEMENT DETAILS WITH EXPLANATIONLOCATION 3 (MAKING OF PRESTRESSED GIRDERS)

All the structures above the pier are prefabricated and prestressed in a casting plant. The pier cap, which is of Y-section is made of as a post tensioned structure:1. The reinforcement cage for the pier cap was made and shuttering arrangements are given with tendons for post tensioning in transverse direction to the rail.2. Separate arrangements are given for shear key and connections with both pier and U girders.3. Concreting is done and it is allowed to achieve sufficient strength and post tensioning is done.4. Out of four tendons two is post tensioned at plant and remaining two will be post tensioned after erection.

Fig.11 MAKING OF PIER CAP The Girder, which is of U-section is made of as a pretensioned structure: 1. The maximum length to which the U Girder can be casted is 51.8m is divided into sub sections based on construction convenience.2. High tension steel wires are pre tensioned with in reinforcement gauge in horizontal manner along longitudinal direction before concreting. 3. The tendons are pulled by 750mm using hydraulic jack in one end by keeping the other end fixed.4. The concrete used is M60 grade and after 3 to 4 days the tendons are released slowly.

Fig.12 MAKING OF PRESTRESSED U-GIRDERS

Fig.13 REINFOCEMENT DETAILS OF PRESTRESSED U-GIRDERS

MEETING WITH COLLECTOR

Fig.14 A MEET WITH COLLECTOR

Fig.15 GROUP PHOTO WITH COLLECTOR AND L&T PROJECT MANAGER

CONCLUSIONThe field visit was very much useful to us. We have learned to a great extent about the construction procedures of pile and casting techniques of prestressed girders.