Large-scale dynamic model testing facility for offshore geotechnology

Abstract

Offshore pipelines are used for the conveyance of oil and gas from offshore fields to onshore facilities or vice versa. Such pipelines undersea are subjected to several forces including large hydrostatic pressure, strong wave action, forces due to temperature and pressure, forces generated during pipe laying process, earthquake forces, etc. This paper outlines the facility and procedure of large-scale geotechnical dynamic model tests at IIT Delhi for such critical conditions of offshore pipelines. With the aid of servo-controlled hydraulic actuators, large-scale model tests can be done to study the response of offshore buried pipelines addressing the problems like (i) upheaval buckling, (ii) lateral buckling, (iii) fatigue and fracture of pipe, (iv) on-bottom stability, and (v) earthquake-induced ground deformation and response of pipelines. The properties and dimensions of offshore pipelines and soil can be scaled down as per the requirement of model testing using appropriate scaling laws. During the model testing, various responses can be recorded such as distribution of pressure, vertical and lateral movement of pipelines, ground movement, time-acceleration response through the sensitive sensors attached with data acquisition system to address the various critical issues of offshore pipelines. The large-scale dynamic model testing facility established at the Department of Civil Engineering of IIT Delhi can be customized as per the requirement of testing of offshore problem. The facility will be useful for both elemental testing of soil/rocks and model testing of any offshore structures.