The Influence of Groundwater Level on the Structural Behaviour of a Pavement Structure Using FWD

Download
Farhad Salour

The effect of groundwater table level on the structural response of an instrumented flexible pavement in southern Sweden was studied using multilevel Falling Weight Deflectometer (FWD) testing. In order to raise the groundwater table level under the pavement structure, the outlets of the pavement’s subsurface drainage system was blocked for three months. Thereafter, it was unblocked, allowing the pavement to recover to its normal draining condition. During this period, variations in the groundwater level and subsurface volumetric moisture content were registered. Manipulation of the drainage system significantly affected the ground water level and the pavement unbound layers moisture conditions. Both the granular layer and the subgrade stiffness significantly decreased with increasing moisture content. In all the FWDs performed, the granular materials exhibited stress-hardening behaviour. However, the subgrade showed stress-softening response in unsaturated condition and stress-independent behaviour in saturated state. In an attempt to determine the k-theta model parameters from the backcalculated internal stresses and unboundlayers moduli, it was observed that the k1 parameter decreased with increasing moisture content for both the granular layer and the unsaturated subgrade materials.

MEET US


19-20
Oct

ERPUG 2017

The five year anniversary of  European Road Profile Users' Group (ERPUG) Forum will take place at Ramboll head quarter, Copenhagen, Denmark October 19-20, 2017. 

LATEST NEWS


2017-07-05

Vehicle Driver Monitoring: sleepiness and cognitive load

To prevent road crashes it is important to understand driver related contributing factors, which have been suggested to be the critical reason in 94 per cent of crashes. The overall aim of the project Vehicle Driver Monitoring has been to advance the...


2017-06-29

Tomas Svensson new director-general

Tomas Svensson was today appointed Director-General of VTI. Tomas has been acting Director-General since January 2017. 


2017-05-30

Crash testing bicycles at VTI

For the first time single bicycle crashes have been simulated at the VTI crash safety laboratory.


2017-05-15

A case study exploring firefighters’ and municipal officials’ preparedness for electrical vehicles

A VTI-study presents a social perspective on new vehicle technology. It explores the self-reported preparedness of the fire departments (i.e., rescue services) in Sweden’s three largest cities regarding rescue operations involving electrical vehicles (EVs).


2017-05-02

Pioneering research on and about bicycles at VTI

Under what circumstances might cyclists lose tyre grip? What actions could then be taken to prevent a crash? VTI is currently developing a theoretical model of the behaviour of bicycle tyres during braking and steering in different situations and on different...


2017-05-02

Virtual pedestrians create efficient stations

If more people are to choose sustainable travel, then the public transport stations of the future must be designed so that pedestrians can get where they are going quickly, without congestion or queues. The Swedish Road and Transport Research Institute (VTI)...