This project includes the geotechnical investigation and assessment of underground soil and groundwater conditions and the design and construction of the temporary lateral support system of a 5.50m excavation for the construction of underground basements of the office building on the roads Varatasi and Favierou at the center of Chalkis. The geotechnical investigation started with the preliminary opening of two investigation shafts in the area of the excavationand continued with the execution of a 12m rotary drilling borehole, in-situ testing and collection of representative samples for laboratory testing. After the completion of the borehole a standpipe piezometer was installed for the monitoring of the water table level.
Based on the results of the performed geotechnical evaluation, the design of the earth retaining system commenced for the selection of the appropriate lateral support system. The design was based on the in-situ soil conditions and the soil displacement restraints, due to the existence of buildings at the excavation boundary. The lateral support system included the construction of vertical steel HEB-IPB soldier piles, at various axial distances with a 10cm thick shotcrete lagging reinforced with a T188 steel grid and the local use of rakers for the reduction of soil displacements at the limits of the excavation with neighbouring buildings.