Prefabricated Vertical Drains (PVD)

Introduction

In almost all projects which are constructed on compressible, saturated soils, excessive settlement is a problematic issue to deal with. Drainage, can be an effective solution to reduce the soil settlement. Vertical and horizontal drains can be constructed in site, or alternatively manufactured. Obviously using prefabricated vertical drains (PVD) can budget the time and results in more successful outcome. In simple words, vertical drains are aimed to shorten the drainage path of the pore water.  Consequently it increases the rate of primary consolidation. To boast the efficiency  of prefabricated drains, this method can also be coupled with surcharge or preloading methods.

PVD Characteristics

PVD is made of a plastic core covered by a synthetic geotextile called “filter jacket”. Core functions as a longitudinal path for water flow, while filter jacket is a sieve to restrict soil particles from entering into the core.

PVD Efficiency and Quality Control

The flowing figure make a comparison to evaluate the efficiency of PVD method demonstrating its high performance. Moreover the precision of operation must be controlled during installation and manufacturing process. Here is a brief checklist to conduct a quality control :

• Minimize soil disturbance by choosing the optimized size of drains.
• drain structure must be stiffness enough to remain vertical under loading.
• adjust the penetration rate to reduce the bending moments.