Giulio Curioni

An Ontology of Soil Properties and Processes

Assessing the Underworld (ATU) is a large interdisciplinary UK research project, which addresses challenges in integrated inter-asset maintenance. As assets on the surface of the ground (e.g. roads or pavements) and those buried under it (e.g. pipes and cables) are supported by the ground, the properties and processes of soil affect the performance of these assets to a significant degree. In order to make integrated decisions, it is necessary to combine the knowledge and expertise in multiple areas, such as roads, soil, buried assets, sensing, etc. This requires an underpinning knowledge model, in the form of an ontology. Within this context, we present a new ontology for describing soil properties (e.g. soil strength) and processes (e.g. soil compaction), as well as how they affect each other. This ontology can be used to express how the ground affects and is affected by assets buried under the ground or on the ground surface. The ontology is written in OWL 2 and openly available from the University of Leeds data repository: http://doi.org/10.5518/54.

A Knowledge-Based System for Evaluating the Impact of Soil Properties on the Performance of Utility Location Technologies: Design and Case Study

Non-invasive utility location techniques are vital for maximizing the potential of trenchless technologies, especially within an urban environment. This paper proposes the approach of implementing a knowledge-based system (KBS) for predicting the geophysical properties of the soil by taking into account both the geographical and seasonal variation in soil properties. The key motivation for developing KBS as a prediction methodology is the advantage of being able to gather and integrate both analytical models as well as expert knowledge based upon existing and opportunistic data. The design and implementation of this system are presented as a case study for ground penetrating radar, which is mainly affected by the complex permittivity and electrical conductivity of the soil. Soil electromagnetic semiempirical models are implemented to obtain an estimate of the complex permittivity using geotechnical properties obtained in laboratory tests or found on a national database. Hydrology models are applied to account for variations in soil water content and the associated impact on permittivity values due to changes in precipitation patterns. Results obtained from a ground penetrating radar test site with a long-term monitoring station installed are also presented, showing agreement between measured data and KBS output, and demonstrating potential for improving the effectiveness of utility surveys.

Disposable stepped-frequency GPR and soil measurement devices

Some geophysical and geotechnical scientists would wish to non-invasively measure the electromagnetic properties of soils using inexpensive, even disposable, technology. They may even wish to develop inexpensive and compact low-power GPR equipment for such uses as teaching and mitigation of construction risks during excavation. To this end, a heuristic comparison is made between a commercial Vector Network Analyser (VNA) and two very low cost VNAs sourced from the amateur radio community. The results are used to illustrate the potential for technology transfer from amateur communications to the GPR community, in order that a wider range of technologies be available for inexpensive implementation in GPR and soil spectroscopy studies. It will be shown that even very low-cost gain and phase detection semiconductor devices can be used to develop simple GPR and soil measurement systems capable of being used in the field to compliment GPR survey interpretation, as well as for standalone soil monitoring.

Investigation of soil contamination by iron pipe corrosion and its influence on GPR detection

It has been observed that the corrosion of iron pipes in soil can produce variations in ground conductivity around the pipe, and that the visibility of such pipes to GPR can be greatly reduced. This new investigation and measurement of the permittivity and conductivity of soil contaminated by iron pipe corrosion products produces more accurate knowledge of permittivity and conductivity data and their likely spatial variation with distance from the corroding pipe. The experimental data are the result of monitoring accelerated corrosion over a period of several weeks and using TDR and direct conductivity measurement schemes. FDTD simulations of GPR signals show how the corrosion induced variation in the visibility of the pipe varies with the thickness and shape of the new spatial variations permittivity and conductivity. The results indicate that in the earlier stages of pipe corrosion use of lower GPR frequencies will still detect the pipe, although at lower spatial resolution.

Extending TDR Capability for Measuring Soil Density and Water Content for Field Condition Monitoring

AbstractTime domain reflectometry (TDR) can be used to measure the dry density of compacted soils, although it is believed that TDR could also be used to monitor the long-term performance of aging ...

3D Buried Utility Location Using A Marching-Cross-Section Algorithm for Multi-Sensor Data Fusion

We address the problem of accurately locating buried utility segments by fusing data from multiple sensors using a novel Marching-Cross-Section (MCS) algorithm. Five types of sensors are used in this work: Ground Penetrating Radar (GPR), Passive Magnetic Fields (PMF), Magnetic Gradiometer (MG), Low Frequency Electromagnetic Fields (LFEM) and Vibro-Acoustics (VA). As part of the MCS algorithm, a novel formulation of the extended Kalman Filter (EKF) is proposed for marching existing utility tracks from a scan cross-section (scs) to the next one; novel rules for initializing utilities based on hypothesized detections on the first scs and for associating predicted utility tracks with hypothesized detections in the following scss are introduced. Algorithms are proposed for generating virtual scan lines based on given hypothesized detections when different sensors do not share common scan lines, or when only the coordinates of the hypothesized detections are provided without any information of the actual survey scan lines. The performance of the proposed system is evaluated with both synthetic data and real data. The experimental results in this work demonstrate that the proposed MCS algorithm can locate multiple buried utility segments simultaneously, including both straight and curved utilities, and can separate intersecting segments. By using the probabilities of a hypothesized detection being a pipe or a cable together with its 3D coordinates, the MCS algorithm is able to discriminate a pipe and a cable close to each other. The MCS algorithm can be used for both post- and on-site processing. When it is used on site, the detected tracks on the current scs can help to determine the location and direction of the next scan line. The proposed “multi-utility multi-sensor” system has no limit to the number of buried utilities or the number of sensors, and the more sensor data used, the more buried utility segments can be detected with more accurate location and orientation.

Pipeline Engineering in the Ground: The Impact of Ground Conditions on Pipeline Condition and Maintenance Operations

The ground in which utility service pipelines are buried inevitably controls, to a large degree, the structural performance and progressive deterioration of the pipelines themselves. In a parallel programme of research to the UK Mapping the Underworld (MTU) project, a study of the fundamental properties of the ground, and how they change with the seasons and local physical and chemical contexts, is being conducted at the University of Birmingham, UK. While the results of this study feed into both the operational protocols for the MTU multi-sensor location device and the associated knowledge based system (KBS) that is being created to aid its deployment (both topics being the subjects of separate papers to this conference), the suite of complementary research projects on the ground and its properties provide valuable insights to the pipeline engineer. Geophysics is being used by the research team to explore the state of the ground with the aim of highlighting areas of concern for the structural health of pipelines buried in the ground. Studies of cast iron pipeline corrosion mechanisms have focussed on the changes that the reaction products cause to the surrounding soils, with a particular emphasis on clay soils, and one interesting finding is that these clay-iron reaction products can make the pipelines ‘invisible’ to standard geophysical location devices. Moreover there are other features in the ground that are being targeted (voids, ground wetting and softening due to leakage, ground weakening due to progressive erosion), and these features effectively make the ground more or less ‘visible’ to geophysical technologies. Alongside this work, bespoke tests have been developed for use on site to ‘calibrate’ the geophysics, thereby enhancing the signatures of the features. This paper introduces these parallel research projects and draws out the important findings for pipeline engineers charged with establishing the condition of existing buried assets.