Abstract:
Yudaganawa dagoba in uva province is one of the largest stupes in Sri Lanka which dates back to 2nd century BC. Presently, this colossal stupa with a diameter
about 91.2 m and reaching a height of 13 m is undergoing several issues which
necessitate it to be rehabilitated. The stupa was found in ruins and grown with
vegetation until it has been preserved by subsequent restoration efforts in the
recent past. However, it is not standing at its original height well-matched with the
circumference at its base. Further, existing formation of the structure, existing
foundation and ground condition are unknown. This paper presents structural
assessment of existing stupa and proposal for rehabilitation in order to build the
stupa to its full height.
A literature survey has been carried out to investigate the structural formation of
stupas in ancient Sri Lanka. The geometry of the present stupa and the soil profile
under the stupa were assessed. Material properties have been found with
adequate laboratory testing. Present condition was modelled using finite element
analysis employing SAP 2000 and PLAXIS 2D. The results show that the stresses
generated within the existing stupa due to its self weight is well below than the
compressive strength and the tensile strength of bricks. Based on the results,
several alternative methods are proposed for rehabilitation and the options are
analysed with respect to structural performance along with the existing condition
and the religious beliefs, attitudes and rituals concerning the stupas. The
possibility of cracking in the masonry due to the self weight in each alternative
method was checked using a failure criteria developed based on the modified Von
Mises theory. The final option was selected so as the stresses generated in the
existing brickwork are satisfying the failure criteria and has the minimum
intervention to the stupa in the context of ancient value and the concerns related
to stupas. Consistent with that, it is shown; the existing stupa is capable of taking
the load of proposed solid brick superstructure without showing any possibility of
cracking.
