buried pipeline upheaval buckling

dear all,
in the last few years we have experienced vertical uphaeval buckling of a buried gas pipeline
the maximum uplift hight is 1700 mm from the ground level and it length is 31 metres.operating pressure is 350 bars and the température is 70 °C
the pipeline is buried in desert area plenty of sand and sometimes it crosses the sande dunes
we would like to get informations from experts regarding the deformation is it plastic or elastic, how we can assess this deformation?
is it safe to continue operating the pipeline in this situation and what are the corrective actions?
any document or reference will be very helpful

Dear all,

I agree with scipion request. I'm also interested in knowing about this specific phenomena, and so I will appreciate your helpful.

Thanks in advance.

Deformation is plastic.
During the shutdown cut the line and restore the condition.
Add some flexibility in the pipeline.
Proper stress analysis required.
Chekc Andrew palmer paper

OTC PAPER 6335 is the basis for upheaval buckling calculation

I realize it has been a long time since the original post, but in case someone still needs this expertise, I have extensive experience generating and simulating buried pipelines using generalized FEA software such as Abaqus fully in 3D with as-built geometry. In the models I would be able to "calibrate" the axial soil parameter in order to reproduce the buckle shape, and then determine what longitudinal strain there is, and compare this to allowable strain limits.
Regards,

Curtis P, P.Eng
Senior Mechanical Engineer, FEA Specialist