Abstract
The continuous monitoring of capillary rise via indirect measures aims to predict and generate alerts regarding the soil mass deformations, transport leachate from landfills to the soil surface, and carry salts that can damage buildings. Through time-lapse monitoring of the electromagnetic wave's electrical potential and speed, it is possible to correlate via petrophysical relations the measures of electrical potential, electrical resistivity, and dielectric permittivity to the volumetric water content and capillary height. For this, four acrylic columns filled with civil construction material were instrumented. Column 1 - silver electrodes to measure the potential difference with a bench multimeter that measures the spontaneous potential generated by water flow. Column 2 - low-cost soil moisture sensors that measured the electrical potential and converted to bits. Column 3 - resistivimeter that measured the voltage and that was later converted to electrical resistivity and, Column 4 - 2.6 GHz antenna that measured the speed of the electromagnetic wave that was later converted into dielectric permittivity. The instrumentation assembled proved to be satisfactory to monitor the phenomenon. The monitoring lasted 187 h, and it was found that the maximum capillary height remained constant for a long time.
Highlights
A wide variety of technological applications, such as oil extraction through porous rocks, or ink-jet printing, is fundamentally dependent on capillary flows
In the construction of landfills and pavements, the water that rises through capillarity tends to compromise the pavements' durability; capillary siphoning can occur in dams: capillary water can pass through impermeable barriers and generate percolation through the dam
With timelapse monitoring of the electrical potential and speed of the electromagnetic wave, it is possible to correlate via petrophysical relations the measures of electrical potential, electrical resistivity, and dielectric permittivity to the volumetric water content and capillary height (Revil et al 2003 [1], Loeffler & Bano 2004 [2], Jol 2009 [3], Franzoni & Bandini 2012 [4], Klenk et al 2015 [5], Revil et al 2017 [6], Liu et al 2017 [7], Oliveti & Cardarelli 2019 [8], Gois et al 2019 [9], Gois et al 2020 [10]) few studies relate the indirect measures to capillary height for transient monitoring of long test periods due to the divergence of existing solutions for capillary height in these conditions
Summary
A wide variety of technological applications, such as oil extraction through porous rocks, or ink-jet printing, is fundamentally dependent on capillary flows. The capillary rise phenomenon can be observed in many applied situations affecting the industry, infrastructure, agriculture, and environmental remediation. In agriculture, this phenomenon helps in irrigating plants and is responsible for transporting water with nutrients. It can contribute to the consolidation of the soils that support the buildings and, when there are ionic exchanges, the capillary water can damage the concrete and steel of the foundations of the buildings. It can bring the landfill leach back to the surface. With timelapse monitoring of the electrical potential and speed of the electromagnetic wave, it is possible to correlate via petrophysical relations the measures of electrical potential, electrical resistivity, and dielectric permittivity to the volumetric water content and capillary height (Revil et al 2003 [1], Loeffler & Bano 2004 [2], Jol 2009 [3], Franzoni & Bandini 2012 [4], Klenk et al 2015 [5], Revil et al 2017 [6], Liu et al 2017 [7], Oliveti & Cardarelli 2019 [8], Gois et al 2019 [9], Gois et al 2020 [10]) few studies relate the indirect measures to capillary height for transient monitoring of long test periods due to the divergence of existing solutions for capillary height in these conditions
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