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Feb 16, 2011 Rehabilitation and Maintenance of Drains and Sewers Profile Measurement (Displacement, Deformation, Internal Corrosion and Wear) Optical-electrical displacement measuring devices that are combined with a sewer TV camera are based mainly on the split-beam method. In this method, the pipe to be measured is illuminated not by means of points, but by a special light curtain (sheet) light that is created either with a corresponding optic or by means of a rotating mirror. The light reflected by the object surface is taken up by a receiver optic displaced in the direction of the … |
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Feb 16, 2011 Rehabilitation and Maintenance of Drains and Sewers Profile Measurement (Displacement, Deformation, Internal Corrosion and Wear) Powerful systems for determining the cross-sectional figure use laser measuring devices in combination with a video camera [NN95g] (Abschnitt 4.3.2.1) (Bild 4.3.2.2.3.3) (Bild 4.3.2.2.3.3). For measuring the pipe deformation, the measuring head positions itself automatically normal to the pipe wall and senses this in steps selected by the user by means of a laser distance sensor. The scatter beams reflected from the pipe wall are bundled by an optical … |
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Nov 19, 2004 Rehabilitation and Maintenance of Drains and Sewers Profile Measurement (Displacement, Deformation, Internal Corrosion and Wear) Sonar scanners have up to now only been used as extensions to the laser technology in order to make measurements in partly filled sewers possible (Abschnitt 4.3.2.3) [Campb95]. |
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Nov 19, 2004 (Image: 3D Laser Scan System: Laser-Scanner [FI-Buchm]) Although change of shape of flexible pipes (Abschnitt 2.7.1), deformation of cracked rigid pipes (Abschnitt 2.8.6) cross sectional measurements and internal corrosion associated with this (Abschnitt 2.6.3.2) and mechanical wear (Abschnitt 2.5) of sewers can be recognised through inspection by sewer TV cameras, or while walking through the sewer, quantitative information is only possible with … |
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Nov 19, 2004 (Image: Principle sketch of an "Impulse Echo Radar" with reference to [Lenz97] [Image: S&P GmbH]) Based on investigations carried out throughout the world, it has been determined that the exploration of the embedment by means of geophysical methods is basically possible but that there is a need for further development. One way to a solution is offered by the transfer of the so-called geophysical borehole measuring methods (e.g. gamma sensors, gamma-… |
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Nov 19, 2004
A fully new concept for the acquisition and description of the pipe-soil system from the … |
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Nov 19, 2004 Soil Exploration |
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Nov 19, 2004 There are many methods, instructions and numerous testing devices for testing accessible concrete and reinforced concrete sewers [NN86i] [ACI201] [Augus84] [Kuhne85] [Rybic79]. A review of the most important evaluation values, testing methods and aids is provided in Tabelle 4.3.2.2.5. Further information on testing methods with reference to the various testing aims can be found in [Larjo80] [Grube90] [Pohl69] [Bisle88]. (Table: Possible tests of concrete … |
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Nov 19, 2004 The results of optical inspections (Abschnitt 4.3.2.1) are often not sufficient to describe the condition of the sewers comprehensively and to provide satisfactory answers to questions of damage as well as type and extent of rehabilitation measures. In order carry out technically and economically based rehabilitation measures it may be necessary to carry out qualitative as well as quantitative determination of the actual condition (Abschnitt 4.2). |
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Jan 01, 1900 The methods presented below also deal with new developments that have not yet been used in practice. In all cases, an attempt is made, with the help of simultaneously utilised sensors to obtain different information on the actual condition of the respective sewers and, in some cases, of their bedding.
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Nov 19, 2004 The (KARO system) sewer robot has been conceived primarily for the inspection of concrete and vitrified clay sewers DN 200 to DN 500 and with a length of up to 400 m (Bild 4.3.2.3.1) (Bild 4.3.2.3.1) (Bild 4.3.2.3.1) [Kuntz95]. Besides a high resolution TV technology, the modular system concept consists of various sensors, especially optical, ultrasonic and microwave sensors that are in a position to detect the type, position and extent of damage … |
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Nov 19, 2004 A newly developed measuring system combining laser and ultrasonic measurement has been developed within the scope of the PIRAT project (Pipe Inspection Rapid Assessment Technique) by CSIRO, Australian and Melbourne Water [Campb95]. In this technique, the inner geometry of the sewers (including damage) is measured and then the data are analysed, identified and classified with the aid of modern computer methods. Depending on the level of the water, … |
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Nov 19, 2004 Also meant for internal inspection is the SSET system (Sewer System Evaluation Technology) being developed [FI-TOA] by TOA Grout Corp. & TGS Comp. in Japan. A combination of video inspection, scan and centrifugal techniques is meant to make the acquisition of the internal pipe surface possible in the form of a coating figure of the complete section of the sewer. Damage is identified and described by a colour and longitudinal horizontal and vertical … |
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Nov 19, 2004 (Image: Non-destructive hammer test with the Sonomolch with reference to [Kling94] [Image: S&P GmbH]) Acoustic methods can be used in order to discover non-visible damage. Besides information on corrosion on the external wall and bedding errors, measurements of the wall thickness as well as the course, position and depth of cracks are possible. A further aim of acoustic sewer inspection is the detection of errors in the operating condition with filled … |
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Nov 19, 2004 The methods presented below also deal with new developments that have not yet been used in practice. In all cases, an attempt is made, with the help of simultaneously utilised sensors to obtain different information on the actual condition of the respective sewers and, in some cases, of their bedding.
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Nov 19, 2004 Internal inspection includes all measures for determining and evaluating the actual condition of drains and sewers, manholes and the embedment or the immediate surrounding soil (Abschnitt 4.3.1.2) from inside. One distinguishes in this between the qualitative and the quantitative condition acquisition (Bild 4.3). Which of the methods and processes are to be used in the particular case under consideration, depends primarily on the nature of the inspection … |
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(Image: Methods for structural investigations of drains and sewers (the methods of engineering measurements for application in accessible sewers are not shown)) The determination of the actual structural condition of sewers is carried out qualitatively with the aid of optical processes and quantitatively by the use of suitable measurement and testing processes. A review of the processes used in practice for this purpose, and that are not as a rule … |
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Nov 19, 2004 Depending on the respective aims of a flow measurement, very different hydraulic situations will occur in the cross section to be measured for which not all measuring methods and certainly not all measuring instruments are equally suitable. If, for instance, it is meant to gather data on the hydraulic loading and capabilities of the sewer, then a large bandwidth of flow conditions up to possible complete filling under a backwater must be acquired. |
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Feb 16, 2011
The selection of the site for measurement is decisive for the results of a flow measurement. Measuring methods and devices, which, because of the system, have a guaranteed rate of error of no more than a few percentage points, can generate operating errors of more than 20 percent when the required hydraulic … |
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Feb 16, 2011 The time of the measurements, also, are determined largely by the purpose. The measurement must take place primarily at a time in which the flow section of the sewer of interest can be viewed as isolated as possible from other part flows. Investigations for determining the extraneous water share through infiltration of groundwater are, for example, carried out at about 2 am on a dry night. At this time the flow of domestic sewage is about zero so … |
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Feb 16, 2011 Basically, flow measurements can be separated into short-time and continuous measurements. In the short time measurements, one deals mostly with individual measurements, control or calibration measurements [DIN19559-1:1983]. If a particular event is to be measured with the help of the flow measurements, such as for instance, a strong downpour event, then a particular single measurement is undertaken. These measurements can be extended to multiple … |
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Feb 16, 2011 Rehabilitation and Maintenance of Drains and Sewers Flow Measurement Procedure Without Cross-Sectional Restriction The simplest but also least accurate method of determining the volume flow for a free flow is the calculation of the median flow velocity by means of partially empirically developed flow formulae. In these, the friction forces at the sewer walls are accounted for by means of coefficients. An example of this is the Manning-Strickler formula: v = K ยท I1/2 ยท Rh2/3Where K = Coefficient of friction in [m1/3s-1]I = Energy line gradient [-] and Rh = Hydraulic … |
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Feb 16, 2011 Rehabilitation and Maintenance of Drains and Sewers Flow Measurement Procedure Without Cross-Sectional Restriction (Image: Volumetric measurement with a pivot counter [Bonfi87]) Volumetric procedures can be used for the determination of very small volume flows, for short-term applications or for calibration. In these methods, the volume (by means of calibrated containers) and the time can be measured at the same time. In order to automate the method for long-term measurements, tipping counters are often used (Bild 4.4.1.5.1.2). The two-chamber container rotates … |
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(Image: Velocity distribution in a partly filled circular pipe [Valen94]) For circular pipes filled one-third to two-thirds full it is known that the median flow velocity vm required for the calculation of the volume flow, is in a constant relationship to the measurable maximum velocity vmax. Under ideal conditions this factor k is equal to 0.82 [Valen89]. Under actual conditions, which are determined by the relatively large velocity sensors employed … |
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(Image: Cross sectional profile of a sewage collector of the City of Frankfurt [Kölli]) With the help of a numerical flow model that has been developed at the TU Munich [Kölli95], it is now possible to determine the k factor for almost any desired open channel section (also natural) and a large bandwidth of grades of filling with which a single point measured maximum velocity must be multiplied in order to determine the median flow velocity vm required … |
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