During the construction of the Lešće Hydropower Plant (HPP) in 2007, 2008, and 2009, geotechnical and geological consulting services were provided, covering the dam, spillway, powerhouse, power tunnel, and grout curtain of the hydropower plant, as well as the Ribnjak and Dobra bridges.
The following activities were carried out:
1. Engineering-geological surveying (mapping) of foundation pits for the dam, spillway, powerhouse, and power tunnel, as well as slopes and cuts above the powerhouse and spillway,
2. Process control of preparation and quality control testing of the grout mix for the grout curtain,
3. Additional geotechnical investigation works for the powerhouse,
4. Geotechnical and geological consulting during the investigation works and construction of the Ribnjak and Dobra bridges,
5. Material compaction testing using a circular plate
The purpose of the consulting services was to verify design assumptions and to optimize and ensure construction quality through geological and geotechnical advice, as well as the monitoring and guidance of construction activities.
Engineering geological mapping during the construction phase determined the state of the rock mass and provided engineering geological elements for the foundation of buildings, which were compared with the project settings. The results of engineering geological mapping are shown on the engineering geological situation and on IG profiles in M 1:200, which show different engineering geological environments, as well as the present discontinuities and their characteristics. The RMR (GSI) rock mass classification was provided for various engineering-geological environments, and mapped excavations were photographically documented for each project element.
The results of control tests on constituent materials and the grout mix, as well as tests on grout mix properties during the construction of the grout curtain at the Lešće HPP reservoir site, complied with the technical material quality specifications defined in the project documentation.
Due to the presence of faults in the powerhouse foundation zone, additional investigative works were carried out; these included geotechnical exploratory drilling, engineering-geological mapping and core logging, laboratory sample testing, geophysical surveys, and the preparation of a geotechnical report, which served as the basis for the technical solution regarding foundation soil preparation.
Geotechnical and geological consulting during the construction phase of the Ribnjak and Dobra bridge, combined with the use of data from earlier investigations, provided insight into the rock mass condition and yielded engineering-geological parameters for the bridge foundations as well as recommendations for construction execution.
Compaction testing using the plate load method was performed on material placed in the abutment wedges of the Ribnjak and Dobra bridge; on material used for the embankments, subgrades, and base courses of access and connecting roads; and on material used for the embankments, subgrades, and base courses of the left-bank barrier and the dam plateau.
Lešće.