Underground Pipe Network Research Articles

GPRS-Based Network of Underground Gas Pipeline Leak Detection System

This article describes the overall structure and components of the gas leak detection system for underground pipe network, proposed difficulties and solutions that exist in the system design process, analyzed how to use the existing wireless GPRS network and gas sensing technology, real-time monitoring of the underground pipe network gas leak from the means of detection, data transmission, measures to combat environmental aspects.

Short-term HDPE pipe degradation upon exposure to aggressive environments

Natural gas and drinkable water are regularly transported by underground polyethylene pipe networks in urban and rural areas. The interaction between materials such as high density polyethylene (HDPE) and contact environments is a critical factor which strongly influences pipe behaviour for short and long terms. The aim of this study is to establish separate effects of H2 SO4 , a mixture of toluene–methanol and distilled water on the mechanical properties of HDPE pipes. Two testing geometries representing the pipe wall are considered: (1) orthogonally machined filaments and (2) ASTM standard specimens. Tensile tests are carried out on both specimen types using a computer controlled Zwick machine. It is observed that chemical environments degrade mechanical properties causing a structural weakening especially those specimens exposed to organic solvent and acid. For instance, filaments show a reduction in elastic modulus of 64% after 7 days of exposure to toluene and methanol. Compared to standard specimens, the obtained properties are much higher indicating that geometry has an effect on the measured values. Fluctuations in mechanical properties are most probably caused by cristallinity gradients all the way through the pipe wall. This type of results allowed establishing the linear relationship between the elastic modulus and the yield stress and is intended to contribute to a better understanding of properties heterogeneity effects when exposed to unfavourable environments.

An Impact Analysis of Constructions in Cities to Construction Security and Environment on Scene

The Capital Constructions in cities will greatly impact the city environment and personal security. It will have a devastating effect to the surrounding environment, municipal roads, and underground pipe network after some major accidents, and even some major casualties, such as the Hangzhou Metro accident, and Shanghai Toppled Building accident, etc. This paper analyzed the reasons of the accidents systematically, and raised suggestions of the information-based construction to prevent such kind of accidents.

A Study on 3D Modeling-Mapping Technology in Underground Pipelines Detection

By collecting the data of the ground scene and non-destructive detecting of the underground pipe network, using freeform software design of the data collected by the three-dimensional color modeling and rapid prototyping systems will underground complex pipeline modeling, using ground-dimensional graphics and three-dimensional model of underground pipe network combined method, This paper is trying to find out an effective presentation method for the distribution of underground pipe network. Thus, an efficient, realistic, intuitive three-dimensional rapid mapping prototyping service technology corresponds to the ground and underground pipe network scenario is applied to urban planning, municipal infrastructure, scientific management, maintenance and reconstruction.

Cylindrical Guided Wave Signals for Underground Pipe Inspection using Different Continuous Wavelet Mother Functions

Over the past decade, wavelets provided a powerful and flexible set of tools for handling fundamental problems in science and engineering. Wavelet analyses are being used for solving problems in different engineering areas like audio de-noising, signal compression, object detection, image decomposition, speech recognition etc. Wavelet analysis employs orthonormal as well as non-orthonornal functions. This research investigates the effectiveness of wavelet analysis in detecting defects in underground steel pipe networks. Continuous Wavelet Transforms (CWT) has been performed on the received signals of cylindrical guided waves. Cylindrical Guided waves are generated and propagated through the pipe wall boundaries in a pitch-catch system. Piezo-electric transducers are used to generate as well as receive guided waves. Several mother wavelet functions such as Daubechies, Symlet, Coiflet and Meyer have been used for the Continuous Wavelet Transform to investigate the most suitable function for defect detection. This research also investigates the effect of surrounding soil on wavelet transforms for different mother wavelet functions.

Flood Wave Modeling Based on a Two-Dimensional Modified Wave Propagation Algorithm Coupled to a Full-Pipe Network Solver

Flood propagation over urban areas can cause an interaction between the free-surface flow and large underground pipe networks used for sewage and storm drainage, causing outflows and inflows at the bed. The waves resulting from these bed discharges may collide with each other and the surface waves, increasing water depths, velocities and accelerations, and their interaction thus affects flood risk. The authors previously introduced a one-dimensional (1D) shallow-water model for simulating free-surface interaction with the flows issuing vertically through finite gaps, referred to as efflux. This model used a modified wave propagation algorithm and was validated by comparing results with the full Navier-Stokes equation solver (STAR-CD) based on the volume-of-fluid method, which models free-surface motion quite generally, although at considerable computational expense. The present paper extends the shallow-water scheme to two dimensions, including source terms for pipe outflow/inflow (efflux/influx) and bed ...

Dynamic reliability under random shocks

The theory of dynamic reliability is extended to explicitly incorporate random changes of the state variables at the time points of transition between the discrete states of the Markovian component of the model. It is shown, that this can be used to model random loads induced by external events, a situation often encountered in structural reliability problems. A state model is developed, which represents the behavior of elementary structures degrading, due to aging processes and stochastic environmental loads. Finally, the structural reliability of the basic components of underground water pipe networks is estimated using the proposed framework.

UtilNets: a water mains rehabilitation decision-support system

UtilNets is a decision-support system (DSS) for rehabilitation planning and optimisation of the maintenance of underground pipe networks of water utilities. The DSS performs reliability based life predictions of the pipes and determines the consequences of maintenance and neglect over time in order to optimise rehabilitation policy.

Soil Temperature Increases Induced by Subsurface Line Heat Sources1

AbstractGenerating electricity using the steam cycle produces large quantities of waste heat. Conversion efficiencies range from 32 to 38% which means that for three units of energy input about one unit of electrical energy is produced and two units of waste heat must be disposed of.Circulating the condenser cooling water through a network of underground pipes would result in warming the soil. The present study was initiated to evaluate the effect of increased soil temperatures on crop growth, the energy balance of the proposed system, and the economic feasibility of the system. This report presents results of the energy balance studies.The proposed system was simulated by electrical heating cables, 92 cm deep with 183 cm spacing, maintained at temperatures ranging from 35 to 37 C. Soil temperatures were measured at hourly intervals over a 2‐year period at points forming arrays in planes perpendicular to the heat sources. The temperature measurements were recorded on magnetic tape and later processed to obtain desired information, such as daily averages at various depths. Energy input was measured with watt‐hour meters. With a bare soil surface the average daily soil Temperature at the 5 cm depth increased about 1.0 C during the summer and 1.5 C during the winter. At the 25 cm depth temperature increases were about 4.0 C and 5.5 C, respectively. The average daily temperature of the profile to a depth of 220 cm was increased about 10 C in the summer and 13 C in the winter. The rate of energy dissipation varied from about 0.012 cal/cm2/min in the summer to about 0.030 cal/cm2/min in the winter. During summer months heat flow from the soil to the atmosphere accounted for less than half of the total flux. During the winter the heat flux to the atmosphere accounted for most of the energy dissipation. Very large surface areas would be required to dissipate the waste eat generated by a power plant with an electrical output of 1,000 MW. The proposed system of soil warming is not an efficient primary heat sink. The rate of heat dissipation could be increased by placing the pipes closer to the soil surface and closer together.

New aspect of buried urban telephone distribution

In 1955, the Bell System initiated a program for developing the necessary methods, tools, and materials to permit construction of economical buried telephone distribution plant. The buried installations up to that time were generally costly, compared with conventional aerial plant, and were in most instances restricted to very-high-priced residential areas. The postwar development of plastic insulated conductor (PIC) cable and the associated ready-access type of terminations made the prospects quite promising. This paper summarizes results achieved to date and describes those methods, tools, and materials which have produced the best results. The term “telephone distribution” includes the subscriber loop plant from the central office to the customer's premise. Urban (in contrast to rural) denotes a built-up area, served by a network of metallic underground utility pipes which tends to act as a ground network in the event of lightning. Methods, tools, and materials used in urban and rural installations are basically the same except that added precautions must, in many instances, be included to prevent lightning damage in rural areas.