In order to reinforce loose soils during construction of the M-12 Highway in the Nizhny Novgorod Region, builders install the textile and compacted sand piles. The state-of-the-art technology is used approximately 30 km from the cable-stayed bridge under construction across the Oka River (near the town of Murom) in the Novashino urban district in the area of Levino, Natalyino settlements, and deep swamps.
A special reinforced ground site is arranged to start the work, which will allow for driving special vehicles in order to install the textile and compacted sand piles.
The piles will transmit the load from the roadway to a solid base bedded under the loose soils. This will allow to avoid continuous replacement of the base under the road, which consists of peat soils to the depth of 12 meters.
Builders use two methods of pile insulation. The first method - vibro piling - involves insulation of a steel displacing leader-tube with a double seat valve by means of a high-frequency vibrator through the loose soils down to the design grade with subsequent placement of a geo shell into the leader tube and filling with sand. Back-lifting of the leader-tube is made with an open valve in the vibration mode. This will enable compacting sand in the pile, expanding the geo shell, and transmitting the compacting horizontal stress to the loose soils of the space between the piles.
The second drilling method involves indentation of a sectional cased pile into the loose soil to the design grade with subsequent drilling-out of excessive soil from the cased pile, placement of the geo shell into the pile, and filling with sand. Back-lifting is also carried out in the vibration mode.