Frank Georg Schulz | TERRATEST

How Soil Bearing Capacity is Determined Using Light Weight Deflectometer

Dec 2nd 2015 at 12:43 AM

The light weight deflectometer is one of the most recent versions of a load bearing capacity measurement equipment, the earlier versions of which can be found in the form of falling weight deflectometers that required heavy weights to simulate deflection. Light weight deflectometers (LWDs) have been around for quite a long time but are only now gaining recognition in engineering and construction fields as more manufacturers emphasize their advantages over other testing devices. LWDs are quite handy in the field as they can be used for determining the soil bearing capacity of pavement surfaces during different stages in the construction process. This is also true for subgrade and sandy surfaces, which are quite difficult to access using the traditional measuring equipment.

Their flexibility, compact nature, and ease of use, make light weight deflectometers a great supplement for various measuring devices and techniques used during different design and construction phases. However, before you replace any of your measuring equipment in place of the more versatile light weight deflectometer, it is important to gain a good understanding of its capabilities and how the results it produces correlate with those of traditional devices. LWDs can and do provide great alternatives to falling weight deflectometers, static plate load and vine test equipment, and the dynamic cone penetrometer, but you should know just how their results compare with these devices to make sure you are getting the right data you need for your design and application.

In any road or foundation construction, initial design processes require thorough examination and measurement of the E-value or the bearing capacity of the subgrade. This is extremely important to accomplish at the early stage of design and construction as this lays the standard for the action to be taken to ensure proper design of the site.

The lightweight deflectometer is essentially a portable falling weight device that performs dynamic load testing. It works by introducing stress to the soil by simulating a load in the form of a light weight, falling from a pre-determined height. This weight transfers force to a load plate, which is laden with sensors that measure deflection. The force of individual measurements at varying drop heights are collected to calculate soil bearing capacity, among many other measurements. This is the same process as a falling weight deflectometer, only it doesn't require a huge vehicle and other difficult to calibrate and handle equipment to facilitate the measurement.

About The Author:
TERRATEST GmbH is world leader in development and manufacturing of Light Weight Deflectometers for dynamic load plate test. They offer the world’s first light weight deflectometer “TERRATEST 5000 BLU” with Bluetooth and voice navigation. For more information about their products visit their website!

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