soft ground improvement techniques soft ground reinforcement company in China

soft ground improvement techniques soft ground reinforcement

The use of prefabricated vertical drains with preloading is now common practice and is proving to be one of the most effective ground improvement techniques known. 

Preloading of soft clay with vertical drains is one of the most popular methods used to increase the shear strength of soft soil and control its post-construction settlement. Since the permeability of soils is very low, consolidation time to the achieved desired settlement or shear strength may take too long. Using prefabricated vertical drains (PVDs), means that the drainage path is shortened from the thickness of the soil layer to the radius of the drain influence zone, which accelerates consolidation. This system has been used to improve the properties of foundation soil for railway embankments, airports, and highways.

Over the past three decades the performance of various types of vertical drains, including sand drains, sand compaction piles, prefabricated vertical drains (geosynthetic) and gravel piles, have been studied. Prefabricated band shaped drains and cardboard wick drains for ground improvement. Typically, prefabricated band drains consist of a plastic core with a longitudinal channel surrounded by a filter jacket to prevent clogging. Most vertical drains are approximately 100 mm wide and 4 mm thick.

To study consolidation due to PVDs, unit cell analysis with a single drain surrounded by a soil cylinder has usually been proposed. PVDs under an embankment not only accelerate consolidation, they also influence the pattern of subsoil deformation. At the centre line of an embankment where lateral displacement is negligible, unit cell solutions are sufficient but elsewhere, especially towards the embankment toe, any prediction from a single drain analysis is not accurate enough because of lateral deformation and heave.

soft ground improvement techniques soft ground reinforcement