Small-scale experimental investigation on the behaviour of nailed slab system in expansive soil

Abstract

Nailed slab system has been developed as an alternative rigid pavement on unstable soils such as soft soil and expansive soil. Nailed slab system is a rigid pavement system, which consists of a thin plate (thickness 12 cm-20 cm) reinforced with micro piles with a diameter of 15 cm-20 cm and a length ranging from 1.5 m − 2.0 m. On soft soil, the nailed slab system can increase the modulus of subgrade reaction and shows better performance than conventional rigid pavement systems in their ability to support the load. However, behaviour nailed slab system on expansive soil still needs to be researched. This research aims to study the behaviour of nailed slab system on expansive swelling soil under heavy and loading test. On expansive soil, nailed slab system was subjected to uplift force due to the soil expansion. Small scale experimental models have been done in the laboratory. Nailed slab system models with a variation in the length of piles have been made. The test results showed upward displacement on nailed slab system were smaller than the slab without pile; pile was functioned as heavy reducer. The upward displacement observed on the unreinforced slab was 57.40 mm and 39.85 mm on a slab reinforced with 25 cm length of pile, decreased the upward displacement of 30.57%. The longer pile produces, the smaller vertical displacement. The Modulus of subgrade reaction on the slab reinforced with 25 cm piles length was two times greater than the unreinforced slab. Soil expansion causes decreased modulus of subgrade reaction, with reinforcing and increasing pile’s length (L) the difference in its modulus of subgrade reaction due to soil expansion decrease.