Light Weight Deflectometer with Geophones and Load Cell

Four years of intense development work have been crowned with success. TERRATEST® on the bauma Shanghai is proud to present its new high-tech model of Light Weight Deflectometer TERRATEST 9000 LWD for the first time, thus reaching the top in the field of light weight deflectometers. This device for measurement uses a central geophone instead of an acceleration sensor, thus significantly increasing the precision in the case of high rigidity. “Meanwhile we are in contact with dealers in Saudi Arabia and Korea, ready to offer our devices in these countries”, explains Sven Krone, CEO of TERRATEST LWD GmbH. “This model is produced particularly for export, as no test specification in Germany for this type of instrument exists. The situation in USA, Canada, Great Britain, Italy, India and South East Asia however is different, so there is a strong demand.”< The configuration enables two external geophones to be attached additionally, in order to measure settlement at a distance of up to 60 cm. An integrated load cell is provided as well, so that falling height, plate diameter and mass of the falling weight can be optimized by the user whenever needed. The four plate diameters amount to 100, 150, 200 and 300 mm; falling weights with a mass of 10, 15 and 20 kg can be used. The load measurement is correspondingly taken into consideration for the calculation.

Production enhanced by Synergy Effects

For the production, TERRATEST® can exploit synergies, which becomes obvious by the optical appearance of the device, hexagonal shape of the falling weight and the inclined load plate handles. Development of smartphone App and software is based on proven resources as well.

The new light weight deflectometer TERRATEST 9000 LWD has been conceived for international markets, and results from a development phase of four years. The instrument features a central geophone and a load cell; two external geophones can be attached as well.

Light Weight Deflectometer in Use on Interstate Highway No.1

Bridge construction works for interstate highway no. 1 in Germany are currently successfully supported by TERRATEST’s model 4000 STREAM. For the Volmarstein viaduct with a length of 315 m, which is frequented everyday by more than 100,000 vehicles, recalculations of the statics have revealed the presence of flaws not to be corrected by sanitation. “For this reason, a completely new construction of the bridge proved to be necessary. For the abutments of the new bridge piers, we are establishing a reinforced soil construction”, explains builder’s manager Michael Rehmann. “This includes an integrated frost protection layer with a graining of 45 - and the lightweight deflectometer is a valuable assistance for performing dynamic load plate tests on each second layer of the gravel base, so its bearing capacity permanently remains under control.”

A reinforced soil construction represents a special form of retaining wall and was invented in the sixties of the past century by the French engineer Henri Vidal. Tensile loads are directed to a reinforcement inserted into the soil, and then conveniently distributed. This reinforcement is usually made of plastics in order to avoid corrosion problems. The new abutments and piers are placed between the former elements, so the length of the bridge is reduced to 285 m. Its width of 31 m exceeds the value of the old bridge by 2 m and offers three lanes in either direction. The construction is intended to be completed in the year of 2020.