Geophysical Methods and their Applications in Dam Safety Monitoring

Abstract

The use of geophysical methods in dam sites investigations and safety monitory has proved their good value and versatility in many earthfill dam sites as early as the 1920s. In the following years great development has occurred in the methods, application procedures and tools used. They may be considered today as good ways for carrying out observation tasks on existing dams in non-intrusive and much faster and cheaper ways than the traditional geotechnical methods. It is possible using them to discover anomalies in the dam body or its foundation at an early stage and allowing quick intervention repair works. These methods seek to register and present variations in the basic geotechnical material properties in dams such as; bulk density, moisture content, elasticity, mechanical properties of rocks, electrical resistivity and mineralogy and magnetic properties and so forth. Such variations can indicate increasing seepage flow, progression in cracks’ sizes, formation of voids, caverns and other instability manifestations. Depending on how any investigation is carried out and the targeted anomaly, there is now selection of these methods such as: Electromagnetic Profiling (EM), Electrical Resistivity Tomography (ERT), SelfPotential (SP), Ground Penetration Radar (GPR), variety of Seismic Methods (SM) which can be applied using such equipment as in Seismic refraction, Seismic Reflection, Multi Analysis of Rayleigh surface waves (MASW) instruments, or using Refraction Micrometer (ReMi), macro-gravity method, and Cross-Hole Seismic Tomography. In addition, Temperature Measurements and other less used methods can be used like Microgravity measurement, Magnetic Profiling and Radio Magnetotelluric methods. An attempt is made here to cover the details of these methods, their advantages and limitations and to prove their usefulness in many dam sites all over the world. One observed issue is their adaptability to embankment dams more than to concrete dams and their popularity for checking seepage related problems and material changes within dam bodies and their foundations such as formation of voids and sinkholes.

Characterisation of the Dynamics of Leachate Contamination Plumes in the Surrounding of the Hulene - B Waste Dump, Maputo, Mozambique

“…In recent years with the awareness of the increasingly complex environmental issues, geophysical prospection methods started to be successfully used in the study of complex environments, such as urban areas [45,46]. Among the geophysical methods most employed in environmental studies the electrical resistivity has been pointed out as relevant [21,22], and it has been prominent in the study of environmental problems in soil and groundwater, mainly in the location of buried hazardous waste, contamination from different sources and the planning of safe sites for the deposit of industrial and domestic waste [26,28] being widely used to identify areas of heavy metal contamination, contamination plumes [10], groundwater [22,47], lithological variations [26]. Leachates when they meet geological materials, cause the natural electrical resistivity of the material to decrease due to the high concentration of dissolved metal ions, creating anomalous resistive zones [27,48].…”

“…Many methods are currently used to study contamination problems in solid waste disposal areas and geophysical methods are pointed out as effective in identifying waste contaminated areas [21,22]. Among these methods, electrical resistivity is widely applied due to its non-invasive nature in data acquisition and processing [23,24,25].…”

Landslide Zone Investigation by Determining Cracks and Cracks Compressive Strength Test in Waru District, Pamekasan Regency

“…Electrical resistivity tomography (ERT) can describe two types of faulty surface geometry (surface landslides and collapsed surfaces), and identifies three external shapes in ancient river basins, landslide bodies and collapse bodies [5] . The ERT method seeks to register and present variations in the properties of basic geotechnical materials in dams such as; bulk density, moisture content, elasticity, rock mechanical properties, electrical resistance and mineralogical and magnetic properties, and so on [6] . The objective of the ERT survey is to characterize the geometry of the landslide section [7] .…”

Economic efficiency of application of geophysical methods in diagnosis of technical condition of regulatory pool

“…В зв'язку з цим набувають актуальності дослідження, які дозволять з оптимальним співвідношенням за витратами часу та коштів отримати дані про технічний стан зрошувальних систем та їх складових, зокрема магістральних каналів (МК) та регулюючих басейнів (РБ). В роботах [3][4][5][6] розглядались результати польових досліджень технічного стану гідротехнічних споруд (ГТС) різного класу наслідків (відповідальності), в тому числі і СС-1, до яких як правило, відносяться регулюючі басейни та канали зрошувальних систем. Наприклад, в Інституті водних проблем і меліорації НААН України застосовувався комплекс методів мікроелектрозондування (МЕЗ), електричного профілювання (ЕП) та природного електричного поля (ПЕП) для оцінки технічного стану магістральних каналів [7][8][9].…”

“…Постановка задачі і методика дослідження. Діагностування технічного стану регулюючого басейну РБ-2 СТЗС комплексом геофізичних методів ПІЕМПЗ і ВЕЗ було виконано раніше і детально розглянуто в роботі авторів [6]. Досліджуваний об'єкт розташований біля с. Малозахарине Солонянського району Дніпропетровської області (рис.…”