Geotechnical Design and Mitigation Measures for the Conservation of Akapana Pyramid in the Tiwanaku Archaeological Site (Bolivia)

Tiwanaku is an Archaeological World Heritage Site, located at an elevation of 3,885 m.a.s.l., south of Lake Titicaca (La Paz), in the high plateau region of Bolivia. The present paper reports the actions carried out in the frame of the project: “Preservacion y conservacion de Tiwanaku y la piramide de Akapana, Bolivia”. The consultancy was requested by UNESCO Office in Quito, following previous activities conducted since 2010 and directly by the CIAAAT. During the first mission in the archaeological site of Tiwanaku (from 9 to 16 May 2016), an interdisciplinary team, carried out the preliminary diagnosis concerning the geotechnical processes affecting the Akapana pyramid. After that, another filed mission was carried out in order to implement a general master plan of actions aimed at the conservation and risk reduction of the whole pyramid. For this scope during 2017 two different field survey were carried out. Main scope of the activities was: (i) prepare and develop a long term executive full proposal conservation project for the Pyramid; (ii) implement a Terrestrial Laser Scanning (TLS) survey in order to produce a very detail topographical setting of the whole pyramid; (iii) collect core drilling samples in the Akapana pyramid for laboratory analysis; (iv) perform stability analysis 3D Model; (v) identify mitigation measures for a test site. After the summer 2017 field mission, the main topographical outcomes of the TLS survey were elaborated, incorporated and adopted for the implementation a pilot project of mitigation measures. Final design has been implemented along the east flank of the pyramid, and support was given to. local authorities and workers during all the mitigation measures implementation.