Dams: Bitumen Joint Monitoring

Case study: DiTeSt System

DiTeSt SMARTape dam monitoring
Threshold detection software used
SPST device used as redundancy for warnings
Strain and temperature monitoring

Project Description

Summary: Structural monitoring of three bitumen joints, with a total length of 250 m approximately, using DiTeSt SMARTape and Temperature Sensing Sensors in order to prevent damage and inundation of a dam inspection gallery.

Clients: Latvenergo, Latvia

Place: Plavinu hes, Aizkraukle (Latvia)

Period: 2004 - N/A

Installation: VND2 Ltd., SMARTEC SA

Structure's short description: Plavinu hes is a dam belongs to the complex of three most important hydropower stations on the Daugava river in Latvia. In terms of capacity this is the largest hydropower plant in Latvia and is considered to be the third level of the Daugavas hydro-electric cascade. It was constructed 107 km distant from the firth of Daugava and is unique in terms of its construction - for the first time in the history of hydro-construction practice, a hydropower plant was built on clay-sand and sand-clay foundations with a maximum pressure limit of 40 m. The HPP building is merged with a water spillway. The entire building complex is extremely compact. There are ten hydro-aggregates installed at the hydropower plant and its current capacity is 870,000 kW.

Aim of monitoring: One of the dam inspection galleries coincides with a system of three bitumen joints that connects two separate blocks of the dam. Due to abrasion of water, the joints lose the bitumen and the redistribution of loads in concrete arms appears. Since the structure is nearly 40 years old, the structural condition of the concrete can be compromised due to ageing. Thus, the redistribution of loads can provoke damage of concrete arm and as a consequence the inundation of the gallery. In order to increase the safety and enhance the management activities it was decided to monitor the average strain in the concrete arm next to the joints. The DiTeSt system with SMARTape deformation sensor and Temperature Sensing Cable is used for this purpose. The sensors were installed by company VND2 with SMARTEC support and configured remotely from the SMARTEC office. Threshold detection software with SPST (open-ground) module was installed in order to send pre-warnings and warnings from the DiTeSt instrument to the Control Office.

Number of sensor: 2

Main Results: Non-disclosed

Installation of SMARTape and Temperature Sensing Cable

DiTeSt reading unit installed in the rack executes a scan

Bibliography:

Overview of fibre optic sensing to structural health monitoring applications , D. Inaudi, ISISS'2005, International Symposium on Innovation & Sustainability of Structures in Civil Engineering, Nanjing, China, November 20-22, 2005

Field Applications of Fiber Optic Strain and Temperature Monitoring Systems , D. Inaudi, B. Glisic, Opto-electronic Sensor-based Monitoring in Geo-engineering,Nanjing, P.R.China, November 23-24, 2005

Application of distributed Fiber Optic Sensory for SHM , D. Inaudi, B. Glisic, 2nd International Conference on Structural Health Monitoring of Intelligent Infrastructure (SHMII-2'2005), Shenzhen, China, November 16-18, 2005

Reliability and field testing of distributed strain and temperature sensors , D. Inaudi, B. Glisic, SPIE Smart Structures and Materials Conference in San Diego. 2006 February 27, March 2, 2006

Health monitoring with optical fiber sensors: from human body to civil structures , ?ic Pinet, Caroline Hamel, Branko Gli?ic, Daniele Inaudi, Nicolae Miron, 14th SPIE Annual Symposium on Smart Structures and Materials & Nondestructive Evaluation and Health Monitoring, San Diego (CA), USA, 6532-19, 2007

Distributed Fiber Optic Sensors: Novel Tools for the Monitoring of Large Structures , Daniele Inaudi, Branko Glisic, Geotechnical News, Volume 25, Number 3, Pages 8-12, 2007

Fibre Optic Methods for Structural Health Monitoring , Branko Glisic and Daniele Inaudi, Johh Wiley & Sons, Ltd, 2007