Vertical Walls with Concrete Facing Panels
HYDERABAD - ANDHRA PRADESH - India
APRDC and R&B, Andhra Pradesh
FOUR LANING OF HYDERABAD – KARIMNAGAR-RAMAGUNDAM ROAD (SH-01)
Photo 1: Spreading of fly ash
Photo 2 : Laying of ParaWeb®
Photo 3 : Placement and joining of MacDrain®
Photo 4 : After placement of MacDrain® behind the bottom panel
Photo 5: Compaction of fly ash
Photo 6 : Compaction of fly ash
Hyderabad – Karimnagar – Ramagundam road is state highway (SH-01) also known as Rajiv Rahadari, connecting Karimnagar and coal belt Ramagundam to the capital city of Hyderabad. The starting point of this highway is Secunderabad. It goes ahead to join the National Highway-16 at the crossroads of Godavarikhani- Mancherial-Chennur. Running over a stretch of 235 km it passes through Adilabad, Karimnagar, Medak and Ranga Reddy districts of Andhra Pradesh. Various structures such as Rail Over Bridge (ROB), Vehicle Under Pass (VUP) and Cattle Under Pass (CUP) needed to be constructed. The approaches of the ROB were to be retained by reinforced soil wall. From the tests conducted in different boreholes along the road, it was found that the soil was silty sand with moorum upto depths of 3m and the below this depth it was weathered rock.
Maccaferri proposed reinforced soil wall with concrete panels as facia. ParaWeb® as reinforcement was adopted due to its technical and economic advantages. As per MoRTH requirement, a 600mm thick gravel filter shall be provided behind the wall as a drainage media to quickly drain off excess pore water that may develop behind the wall. Maccaferri proposed a better alternative solution – placing a layer of MacDrain® (drainage geocomposite) behind the retaining wall, replacing the conventional drainage arrangement of graded gravel layer. MacDrain® is a specifically designed geocomposite to meet the drainage and protection requirements in structurally demanding water draining applications. Drainage composites effectively eliminate hydrostatic pressure against below-grade structures and aid in dewatering saturated soil by collecting and conveying groundwater to a drain pipe for discharge. As Ramagundam has a coal based power plant, lot of fly ash is being generated. Use of fly ash with structural fill has been adopted due to the enormous availability of fly ash and added advantages of it being used in the embankment fill due to its properties like low unit weight and high shear strength, there by reducing the stresses. The pozzolanic hardening of fly ash imparts additional strength and very little settlements, making it more suitable.