Buried Pipe Network Research Articles

Acoustic Echo Sensing for Robot Localization in Buried Pipe Networks

Acoustic Echo Sensing for Robot Localization in Buried Pipe Networks

Real-time robot topological localization and mapping with limited visual sampling in simulated buried pipe networks

Real-time robot topological localization and mapping with limited visual sampling in simulated buried pipe networks

A Comparison of the Performance of Four Acoustic Modulation Techniques for Robot Communication in Pipes

Autonomous robotics is an emerging technology for the inspection of a vast network of underground pipes. Communication between autonomous robots is essential to optimise their efficiency and network coverage. However, sending a message acoustically is not a well-researched topic because most of the existing literature is devoted to the study of the acoustic properties of the pipe for the purpose of sensing rather than communication. In particular, the influence of multi-modal propagation and background noise on the quality of acoustic communication in pipes has not been well understood. This paper studies the performance of four standard acoustic communication techniques in a dry drainage pipe to fill this knowledge gap. The noise resistance, communication range and data rate of these techniques are estimated through numerical simulations and laboratory experiments. It has been found that the techniques based on shift keying requires at least 5--10 dB signal to noise ratio (SNR) to function properly while the chirp linear frequency modulation technique can operate reliably with SNR = 0 dB or event lower SNR. The results also suggest that the multi-modal propagation in the pipe has significant effects on the package error rate. The frequency dependent sound attenuation in the pipe also affects the communication range and data rate. In particular, for a 150 mm diameter dry pipe the maximum robot operation distance is likely to be limited to 50--100 m with the highest carrier frequency of around 10 kHz and data rates below 6300 bps. The results of this work pave the way to the development of acoustic communication modules to be deployed on tetheless robots designed to inspect a buried pipe network autonomously and collaboratively.

Robotic autonomous asset management: benefit/value-based business model creation

Research has shown that value generation is an important factor when it comes to driving technological change. It follows that business models as narratives of value generation and capture have an important part to play as the end goals in the change process. Research also suggests, however, that the understanding of when, why and how value accrues to stakeholders, and what value to create, appears to be lacking. This paper describes an objective and repeatable methodology for the identification of benefit- and value-generating opportunities that can be used to aid business model creation. The methodology is demonstrated for the generic business of infrastructure asset management and discussed in detail in the context of ‘Pipebots’, a current scientific research project into the introduction of robotic and autonomous systems to the asset management of buried water and sewage pipe networks in the UK. In conclusion, the paper proposes that the methodology opens the door to a future where radical change in a given infrastructure system can lead to value capture across the wider system of systems.

A Governance Framework for Implementation of Scientific and Engineering Innovation in Buried Infrastructure Systems

This article draws on experience within a pervasive sensing research project, the Pipebots project. The aim of the project is to design miniature robots to gather physical condition and environmental data on buried pipe networks, using potable water distribution and wastewater pipe systems as the initial target applications. One of the challenges of the project is to anticipate and address the potential governance issues triggered by the project. Due to the lack of a suitable tool with sufficient breadth to guide thinking, the existing literature has been drawn upon to form the basis of a governance framework for use in infrastructure projects. Whilst the original intention was to be alert to and interrogate the forms of governance that may impact on new infrastructure interventions, what is emerging is a tool that would support the strategy for implementation, improve the design (a no-regrets design policy) and help build the business case for the transformational change the project envisages.

Importance of long-term ground-loop temperature variation in performance optimization of Ground Source Heat Pump system

In a recent article published in this journal, a series of design optimization was executed for a ground source heat pump system. The optimization was conducted based on a COPall index, which considers both the hydraulic loss on the buried pipe network, as well as the soil thermal balance over a one-year period. In that article, it was concluded that a borehole spacing of 4 m is the optimal value. In this short communication, the comprehensive COPall index is re-evaluated with the same system setup with both the TRNSYS and OpenGeoSys-TESPy software, but over a 20-year period. The results show that the borehole heat exchanger array with a spacing of 4 m will suffer severe heat accumulation over a 20-year operation. This causes the soil temperature to rise by 5.68 °C, along with a decrease of COPall from 4.59 to 4.18. Due to the smaller increase of ground-loop temperature and lower electricity consumption from heat pumps, a larger spacing of 6 m will bring better COPall value over the long term, and thus should be recommended. The extended numerical study in this work suggests that when evaluating the performance of a ground source heat pump system, different time duration will lead to different results. Therefore, the variation of long-term ground-loop temperature needs to be quantitatively evaluated in advance, and the system optimization is recommended to be conducted over the entire life cycle of the system.

Thermal energy transfer around buried pipe infrastructure

Decarbonisation of heating is essential to meet national and international greenhouse gas emissions targets. This will require adoption of a range of solutions including ground source heat pump and district heating technologies. A novel route to these solutions includes dual use of buried infrastructure for heat transfer and storage in addition to its primary function. Water supply and wastewater collection pipes may be well suited for thermal energy applications being present in all urban areas in networks already in proximity to heat users. However, greater understanding of their potential interactions with surrounding heat sources and sinks is required before full assessment of the energy potential of such buried pipe networks can be obtained. This paper presents an investigation into the thermal interactions associated with shallow, buried water filled pipes. Using the results of large scale experiments and numerical simulation it is shown that soil surface ambient conditions and adjacent pipes can both act as sources or sinks of heat. While conduction is the main mechanism of heat transfer in the soil directly surrounding any pipe, any adjacent water filled pipes may lead to convection becoming important locally. In the test case, the thermal sphere of influence of the water filled pipe was also shown to be large, at in excess of 4 m over a timescale of 4 months. Taken together, these points suggest that design and analysis approaches when using water supply and wastewater collection networks for heat exchange and storage need careful consideration of environmental interactions, heat losses and gains to adjacent pipes or other infrastructure, and in ground conditions for a number of pipe diameters from any buried pipe.

Estimation of Soil Burial and Pavement Thickness using GPR Technique (Case Study)

The ground-penetrating radar (GPR) transmits an electromagnetic wave, and it is a non-destructive test that can be used in geotechnical applications. One of the main benefits of this device is to explore buried underground objects. The study is proposed to find asphalt thickness and compare it with the core test (destructive test) and their error rate. The survey was also intended to detect buried services utilities (pipes, electrical cables, manholes, groundwater level). The current study focuses on finding the device’s error rate using an antenna with medium frequencies of 450 MHz in exploring a network of buried pipes, manholes, and electrical cables and comparing them with the actual execution to find the percentage error of the device. The GPR has relatively high accuracy with an error rate for buried utilities and pavement thickness compared with the actual execution is between 4.3% and 10%.

Acoustic and ultrasonic techniques for defect detection and condition monitoring in water and sewerage pipes: A review

Condition monitoring for water and sewerage pipes is essential for the safety of the environment, energy conservation and human health. This paper focuses on the application of acoustic and ultrasonic techniques for the detection and assessment of leaks, blockages and defect in buried pipes. The review includes acoustic methods (below 20 kHz) based on vibration sensing using accelerometers, hydrophones and fibre optic sensors, and ultrasonic methods (above 20 kHz) based on the propagation of bulk and guided waves. Related data-driven, machine-learning techniques are also discussed. Typical arrangements of sensors are shown, explained and analysed in terms of their applicability to buried pipe networks. Commercial systems and state of the art research for the inspection of pipes made of a range of materials such as cast iron, high-density polyethylene and concrete are critically assessed. This review also explores the future application of autonomous robotics to deploy these sensors in water distribution and sewerage pipes.

THE SEISMIC RESPONSE OF WATER SUPPLY NETWORKS IN RANDOM SEISMIC FIELDS BASED ON PHYSICAL MECHANISMS

Water supply networks are important components of lifeline engineering. Because of the influence of random earthquake motion fields, their seismic response and function also have obvious randomness. The influence of the complicated topological structure of water supply networks cannot be considered by the traditional seismic response analysis of buried pipelines. The traditional method is also difficult to be applied to analyze the random vibration of the nonlinear system. The physical response of pipelines has not been implemented into the functional analysis of water supply networks. To solve these three problems, this paper modifies the random physical model of seismic ground motion fields on the local engineering site, introduces a finite element method of buried pipe networks, combines the probability density evolution method, and realizes the random seismic response analysis of water supply networks. Furthermore, the transient flow theory is utilized, and the random seismic function analysis of water supply networks is completed. It lays foundation for the seismic reliability evaluation of water supply networks.

Failure prediction of buried pipe network with multiple failure modes and spatial randomness of corrosion

Buried pipes, as a significant civil infrastructure, play a vital role in water, oil and gas transports. In this paper, a systematic method is developed to accurately predict the failure probability of a buried pipeline network at various levels of failure mode, pipe segment and whole pipeline system. A framework of system reliability is proposed to integrate the ultimate and serviceability failures. The random field theory is employed to model the distribution of corrosion, considering its spatial and temporal variability. A time-dependent reliability method is used to determine the probability of pipe failures with either the structural response or resistance modeled as a stochastic process. A worked example is presented to illustrate the application of the proposed methodology. It is found that the developed method is able to predict when, where and what to fail in a pipeline network. It is also found that both the spatial variability of corrosion and auto-correlation of stochastic process between two time points have significant impacts on the probability of pipeline system failure. The paper concludes that the developed method can equip pipe engineers and asset managers with a tool in accurately predicting the failure of pipeline network with a view to cost-effective management of the pipeline network.

Reliability of Buried Pipes in Heterogeneous Soil Subjected to Seismic Loads

Dysfunctions and failures of buried pipe networks, like sewer networks, are studied in this paper from the point of view of structural reliability and heterogeneity of geotechnical conditions in the longitudinal direction. Combined soil spatial variability and Peak Ground Acceleration (PGA) induce stresses and displacements. A model has been developed within the frame of geostatistics and a mechanical description of the soil–structure interaction of a set of buried pipes with connections resting on the soil by a two-parameter model (Pasternak model). Structural reliability analysis is performed considering two limit states: Serviceability Limit State (SLS), related to large "counter slope" in a given pipe, and Ultimate Limit State (ULS), corresponding to bending moment.

Simultaneous Localization and Mapping for Inspection Robots in Water and Sewer Pipe Networks: A Review

At the present time, water and sewer pipe networks are predominantly inspected manually. In the near future, smart cities will perform intelligent autonomous monitoring of buried pipe networks, using teams of small robots. These robots, equipped with all necessary computational facilities and sensors (optical, acoustic, inertial, thermal, pressure and others) will be able to inspect pipes whilst navigating, self-localising and communicating information about the pipe condition and faults such as leaks or blockages to human operators for monitoring and decision support. The predominantly manual inspection of pipe networks will be replaced with teams of autonomous inspection robots that can operate for long periods of time over a large spatial scale. Reliable autonomous navigation and reporting of faults at this scale requires effective localization and mapping, which is the estimation of the robot’s position and its surrounding environment. This survey presents an overview of state-of-the-art works on robot simultaneous localization and mapping (SLAM) with a focus on water and sewer pipe networks. It considers various aspects of the SLAM problem in pipes, from the motivation, to the water industry requirements, modern SLAM methods, map-types and sensors suited to pipes. Future challenges such as robustness for long term robot operation in pipes are discussed, including how making use of prior knowledge, e.g. geographic information systems (GIS) can be used to build map estimates, and improve multi-robot SLAM in the pipe environment.

Investigation for a novel optimization design method of ground source heat pump based on hydraulic characteristics of buried pipe network

In this paper, a novel optimal design method for ground source heat pump (GSHP) system based on hydraulic characteristics of buried pipe network (BPN) is proposed. The influence of BPN hydraulic characteristics and soil thermal balance on the operation efficiency of GSHP system are considered. This paper studies the GSHP system of a building in Changsha in the Central and South China Hilly Region. First, referring to the soil thermal property test, a simple simulation model is built using TRNSYS. Furthermore, the influence extent of various factors on soil thermal balance are studied by orthogonal experimental design method (OED). Then, the BPN model of this system is established and TRNSYS is employed to establish the GSHP system model of the building. A comprehensive coefficient of performance of the whole year transportation system (COPall) is presented as the evaluation index to optimize the borehole depth (Bd), borehole spacing (Bs), buried pipe length (Bl) and buried pipe form. These results indicate that, the resistance of vertical buried pipe accounts for 80% of the total resistance in a BPN partition. Reducing the Bl from machine room to BPN by 80% in the whole BPN, and the total resistance decreases by 31.8%. It is found that there is a power function relationship between the average temperature rises of soil (ΔT) and the BPN resistance (H). Considering comprehensively, Bd of this project should be designed within 60 m-100 m and Bs should be designed 4.0 m-5.0 m. When the Bl is certain, the COPall reaches its maximum when the Bs is 3 m. For any Bs between the two buried pipe forms, the Bl corresponding to the maximum COPall is almost the same. They are 25.2 km for single U- tube and 67.2 km for double U- tube respectively. When the Bl is the same, 24 km is the critical length of two buried pipe forms. Our work can provide theoretical basis and guidance for the optimization design of GSHP in similar areas.

Test on a buried pipe network subjected to an artificial earthquake produced by multi-millisecond blasting

Buried pipe networks are important components of lifeline systems. An experiment is conducted to test a buried pipe network subjected to an artificial earthquake produced by multi-millisecond blasting. The motivation of the research is to verify the feasibility of using multi-millisecond blasting to simulate earthquakes and to validate the deformation relationship between pipe and soil obtained in a single-point explosion test. Multiple explosives are used with a time-delay technique to create an extended period of loading on pipes. The dimension of the buried pipe network is 24 m × 24 m. The artificial earthquake is produced by trinitrotoluene (TNT) charges. The pipe network consists of ductile cast iron (DCI) pipes, which represent a water distribution network, and welded steel (WS) pipes, which represent a gas supply network. Eighty-five kilograms of TNT charges, which are divided into three parts, are detonated by millisecond blasting. The ground motion of the test field, including the accelerations and velocities at different points, and the pipe dynamic responses, including the joint deformations of DCI pipes and the axial strains of WS pipes, are described in detail. Finally, the deformation law of buried pipe networks and the deformation relationship between pipe and soil are discussed.

Seismic reliability analysis of water distribution networks on the basis of the probability density evolution method

In this study, a new approach for assessing the seismic functional reliability of water distribution networks is presented on the basis of the probability density evolution method. The original contribution of this paper is to build a new framework for the reliability analysis of water distribution networks on the basis of the physical mechanism of water distribution networks subjected to earthquakes. Firstly, a finite element model is established to capture the seismic response of the entire buried pipe networks. Then the nodal head of water distribution networks is derived through hydraulic analysis of water distribution networks with leakages. Secondly, owing to the randomness of ground motions, the probability density functions of the nodal heads of water distribution networks are obtained on the basis of the probability density evolution method. Thirdly, the seismic functional reliability of water distribution networks is evaluated considering the demand heads of nodes. When the nodal head is larger than the predetermined water head, the node is reliable while when the nodal head is smaller than the predetermined water head, the node is not reliable. Two examples, namely, a virtual and an actual water distribution networks, are examined in detail to investigate the feasibility of the proposed method. Results show that the proposed method effectively evaluates the seismic functional reliability of water distribution networks.

Tsunami impact assessment: development of vulnerability matrix for critical infrastructure and application to Christchurch, New Zealand

Tsunamis can have severe impacts on society. In addition to casualties and damage to buildings, they can also damage and disrupt critical infrastructure. To support effective risk management, it is important to understand the possible extent, severity and duration of these impacts. While impacts on buildings and casualty estimations are relatively well developed for tsunamis, critical infrastructure impact models are either not available or lack accurate vulnerability information. This paper addresses these issues by reviewing global tsunami impacts to critical infrastructure to develop a semi-quantitative tsunami damage matrix for critical infrastructure components and systems. One potential application of the damage matrix is demonstrated within an impact assessment process for Christchurch, New Zealand. The impact assessment determines asset damage likelihood for energy, water, telecommunication and transportation assets from a large tsunami inundation scenario. Consistent with observations from previous international tsunamis, above-ground assets and buried storm water pipe networks in Christchurch were found to perform poorly, while buried potable and waste water pipe networks were less impacted. This process provides a simple, but widely applicable, impact assessment approach which further studies can build on. Future research should focus on developing quantitative probabilistic tsunami vulnerability models for critical infrastructure that implement multiple asset standards and hazard intensity measures, and better account for uncertainty.

Design of smart sensors for real time drinking water quality monitoring and contamination detection in water distributed mains

Drinking Water Distribution Systems facilitate to carry portable water from water resources such as reservoirs, river, and water tanks to industrial, commercial and residential consumers through complex buried pipe networks. Determining the consequences of a water contamination event is an important concern in the field of water systems security and in drinking water distribution systems. The proposed work is based on the development of low cost fuzzy based water quality monitoring system using wireless sensor networks which is capable of measuring physiochemical parameters of water quality such as pH, temperature, conductivity, oxidation reduction potential and turbidity. Based on selected parameters a sensing unit is developed along with several microsystems for analog signal conditioning, data aggregation, sensor data analysis and logging, and remote representation of data to the consumers. Finally, algorithms for fusing the real time data and decision making using fuzzy logic at local level are developed to assess the water contamination risk. Based on the water contamination level in the distribution pipeline the drinking water quality is classified as acceptable/reject/desirable. When the contamination is detected, the sensing unit with ZigBee sends signals to close the solenoid valve inside the pipeline to prevent the flow of contaminated water supply and it intimates the consumers about drinking water quality through mobile app. Experimental results indicate that this low cost real time water quality monitoring system acts as an ideal early warning system with best detection accuracy. The derived solution can also be applied to different IoT (Internet of Things) scenario such as smart cities, the city transport system etc.

The stiffness of axial pipe–soil springs and axial joint springs tested by artificial earthquakes

This study proposes an experimental method to obtain the stiffness of axial pipe–soil and axial joint springs in time and frequency domains. The proposed method can determine axial pipe–soil spring stiffness by using the pipe strains and slippages between pipes and soil. It can also determine axial joint spring stiffness by utilizing pipe strains and joint deformations. The pipe–soil spring stiffness values of ductile cast iron (DCI) and welded steel (WS) pipes are obtained and analyzed through artificial earthquake tests on a 24m × 24m buried pipe network. Artificial earthquakes are produced with trinitrotoluene explosives. Three theoretical models are discussed, and their results are compared with the test results. The comparisons indicate that the proposed experimental method is valid to obtain the stiffness of axial pipe–soil and axial joint springs. The stiffness values can be a benchmark to study the pipe–soil interaction and flexible joints. The effects of axial pipe–soil spring stiffness on the joint deformations of DCI pipes and pipe strains of WS pipes are also discussed.

Seismic reliability evaluation of gas supply networks based on the probability density evolution method

An accurate and efficient reliability evaluation is necessary for network systems with uncertain conditions, especially for the lifeline networks subjected to earthquakes. This study takes gas supply networks as examples and establishes an approach to evaluate the seismic reliability of networks on the basis of the probability density evolution method. First, a nonlinear finite element model is established to simulate buried pipe networks that are subjected to earthquakes. Then, the seismic stresses of the pipes are derived, and the von Mises stresses of the pipes are calculated and used to judge pipe failure. Second, a connectivity index is defined to describe the connectivity between the source and the terminal. Third, on the basis of the probability density evolution method, network reliability is obtained after introducing a physically-based model to simulate ground motion field. Finally, two networks are used as examples to demonstrate the proposed approach, and the results are validated by the Monte Carlo simulation method and compared with a selective recursive decomposition algorithm.