Reinforced soil retaining structures designs – Pelješac Bridge access roads
For the Pelješac bridge projects we have developed the reinforced soil retaining structures main and detailed designs at the positions of the abutments of the Dumanja Jaruga I bridge and the Doli wall as part of the construction of access roads to the bridge on the side of the Pelješac peninsula.
The future Dumanja Jaruga I bridge will start at km 9 + 290 and end at km 9 + 710. It will have four spans of individual lengths of 90.0, 120.0, 120.0 and 90.0 m. The future Doli wall will start at km 8 + 085 and end at km 8 + 265. Because of to the unfavorable geomorphology of the terrain – a valley, where the construction of the embankment in a stable geometry would require the use of a huge amount of material – reinforced soil retaining structures are planned at both locations.
The project envisages to ensure the stability of the embankment in the abutment zones U0 and U4 of the Dumanja Jaruga I bridge and the embankment at the position of the Doli wall, the construction of reinforced soil retaining structures is planned. Retaining structures of 102.0 m and 155.60 m in length are planned for the abutment zones U0 and U4 of the Dumanja Jaruga I bridge, and a retaining structure of 180.0 m in length is planned for the position of the Doli wall.
Reinforced soil retaining structures are executed from the bottom up. The construction follows certain steps, i.e., phases of construction that are in principle always repeated. A reinforced soil retaining structure is composed of individual types that are primarily defined by the height, type and layout of the planned geogrids. The designed height distance of the geogrid is 65.0 cm.
The reinforced soil retaining structures will be executed in several construction phases: phase 1 – Excavation of the existing terrain in the slope in stable geometry for the purpose of constructing a reinforced soil retaining structure, phase 2 – Installation of the first panel of the reinforcing mesh Q-335 in the bottom of the excavation to form the front face of the retaining structure. phase 3 – Installation of geogrids of different lengths depending on the retaining structure coverage area, phase 4 – Installation of composite mesh on a reinforcing mesh panel in order to prevent the erosion of embankment material through the front face of the retaining structure, phase 5 – Installation of reinforcing bars of Φ8.0 mm, made of ribbed reinforcement B 500B for the purpose of stiffening the reinforcement mesh panel (stabilization of the front face of the retaining structure) at every 45.0 cm, phase 6 – Preparation of a layer of reinforced soil 65.0 cm thick, using material filling and compaction in two layers.
After each row of the embankment is executed, appropriate compaction is performed using vibration, while compaction is performed manually along the front face.
By repeating the above phases (from phase 2 to phase 6), the retaining structure is constructed from the reinforced soil to reach full height, and it consists of the following basic parts: soil for the construction of a reinforced soil retaining structure, panel of reinforcing mesh Q-335 and reinforcing bars Φ8.0 mm of ribbed reinforcement B500B to form the front face of the retaining structure at the selected slope, uniaxial geogrid made of high-density polyethylene (HDPE).