|
|
Feb 16, 2011 In air gun seismics (Bild 4.3.1.2.5) (Bild 4.3.1.2.5), the soil particles are excited by means of acoustic wave signals that vary in their frequency with time (sweep) to oscillations. This is in contrast to hammering, explosives, etc. where a single impulse generates the seismic waves.
The advantage … |
||
|
|
Nov 19, 2004 (Image: Physical measurement principle of magnetism [Lenz97]) The magnetic field of earth is very strongly influenced at the surface of the ground by the topmost layer of the underground. In the application region of engineering geophysics, these are not the layers themselves but the structures they contain, such as, for example iron substances, bunkers, tanks, beams, pipelines, scrap, containers and reinforced concrete foundations. Often, these iron … |
||
|
|
Feb 16, 2011 In the process of Electromagnetic Induction (EMI), the subsoil is subjected to an alternating field by means of a coil and this induces a secondary field. This, again, superimposes itself on the exciting field. The resulting field is measured by a receiver coil. Bild 4.3.1.2.7 shows the manual measuring. The frequency region used by the EMI method ranges from about 10 Hz to 2 MHz, the coil spacing varies from a few metres (Bild 4.3.1.2.7) to approximately … |
||
|
|
Feb 16, 2011 In the geo-electrical method, a weak direct current is fed into the underground by means of electrodes. Sensors capture the resulting stationary field potential, which is influenced by the distribution of conductivity of the underground. By means of suitable model calculations, it is possible from these measurement values to obtain the distribution of the true specific resistance in the underground below the sensor point, along a profile or in a … |
||
|
|
Nov 19, 2004 In the soil or geo-radar (EMR = Electro-Magnetic Reflection), an impulse-type high frequency radio wave is sent into the soil from an antenna. The signal is partly reflected from border planes and interference bodies, and sensed by a receiver. The radargram built up in this way can be interpreted to show the underground structures [Lenz97]. Bild 4.3.1.2.9 shows the amplitudes of the reflected signal that change with time as a single point depiction. … |
||
|
|
Feb 16, 2011 Very important for the information received and the reliability of geophysical measurements are the method of the measuring and the proper arrangement of the measuring instruments. It is in the nature of the geophysical data to provide results that can mean a number of things and there is a high degree of complexity in the alternating effects between exciter signals and the answering behaviour of the measured object. Thus, there is a requirement, … |
||
|
|
Nov 19, 2004 Geophysical Soil Exploration |
||
|
|
Nov 19, 2004 Rehabilitation and Maintenance of Drains and Sewers Building Site and Subsoil Exploration by Means of Excavation "Scraping is an artificially created opening for obtaining a view of the construction site, for taking samples and for carrying out field tests." It can be carried out by accessible or non-man-accessible means. Scrapings are suitable mainly for tests above the groundwater or for small inspection depths [DIN4021]. |
||
|
|
Nov 19, 2004 Rehabilitation and Maintenance of Drains and Sewers Building Site and Subsoil Exploration by Means of Excavation "Boring makes possible the exploration in soil and rock up to great depths, its execution is not hindered substantially by groundwater" [DIN4021]. Various methods are used in order to remove the soil depending on the type (rotation, dry core, ram core or compression core drilling). Excavation boring can also be used for observing the groundwater to establish the position, quality and quantity in waterlogged layers or as groundwater measuring positions (… |
||
|
|
Feb 16, 2011 Rehabilitation and Maintenance of Drains and Sewers Building Site and Subsoil Exploration by Means of Excavation According to [DIN4094], the term sounding is defined as "an indirect construction site excavation process in soils, usually by the introduction of a sensor for measuring characteristics of the ingress resistance." One distinguishes between ram, pressure and rotating wing sounding. The various types and possibilities of application of the probe instruments are depicted in Tabelle 4.3.1.3.3. (Table: Types and application possibilities of the sounding … |
||
|
|
Nov 19, 2004 Building Site and Soil Exploration by Means of Excavation |
||
|
|
Nov 19, 2004 External inspection comprises all measures that are carried out from the surface. These include:
|
||
|
|
Feb 16, 2011 (Image: Sewer inspection system for accessible sewage installations [FI-Gully]) The direct optical inspection is carried out by viewing whilst traversing or driving. For structures of drain and sewer systems such as manholes or backflow structures, because of their dimensions or their geometry, it presents in most cases the only sensible or possible measure for determining the actual condition. In the sections of the sewer, this method is permitted … |
||
|
|
Feb 16, 2011 Sewer TV cameras, also called Remote Sewer Eyes, are exclusively used today for optical inspection of non-man-accessible sewers. The installations are constructed on the module principle and can be adapted to almost all requirements by the exchange of lenses, camera and lighting units and the selection of various guide sleds or slides or motorised units, pull or push arrangements and by means of the utilisation of corresponding operating and display … |
||
|
|
Feb 16, 2011 As regards the conveying and control installations, one distinguishes between non-self-propelling and self- propelling cameras. In small nominal sizes, short sections of the sewer and laterals, the camera is usually pushed directly through the sewer by means of endless or extendable glass fibre rods whereby, under certain conditions, even 90° bends present no problems. For controlling or centring the camera unit, radially arranged brushes, sleds … |
||
|
|
Nov 19, 2004
The observation and control installations required for a sewer inspection are either built into an instrument case or are fixedly installed in special inspection vehicles. The instrument case that is usually used for private domain sewers, laterals and for sections of the sewer not accessible to motorised vehicles is equipped, … |
||
|
|
Nov 19, 2004 (Image: Universal test figure T05/DIN 25 435 Part 4 [DIN25435-4]) As the above paragraphs have shown, the most varied systems of sewer inspection for all nominal sizes usual in sewer systems are available today. The requirements to be fulfilled for their use in Germany are formulated in [ATVM143-2] and the most important of them will be mentioned in more detail below:
|
||
|
|
Nov 19, 2004 The oldest and simplest method of gaining an overview of the inner condition of straight laid and non-man-accessible sewers is direct viewing, if necessary, with the aid of sufficient lighting. For the sake of simplicity, use is made of sewer mirroring [Gürsc21]. In this method, a mirror is held at an angle of 45° at the end of the section of the sewer in such manner that an uninterrupted view is possible, whereby the light shines from the next … |
||
|
|
Nov 19, 2004 The foremost technology in internal inspection is the optical condition acquisition. In Germany this is regulated by the ATV-M 143E Part 2 in [ATVM143-2], which will be referred to below. Depending on the methods used, the following can be acquired and qualitatively evaluated (Abschnitt 2.1) :
|
||
|
|
Nov 19, 2004 (Image: Depiction of the principle of the inverted siphon measuring system with reference to [FI-KARO] [Image: S&P GmbH]) Deposits (Abschnitt 2.3.2.1) belong to the damage group of obstacles. They are presently acquired, together with incrustation, projecting flow obstacles and root ingress (Tabelle 2.9) within the scope of optical inspection and estimated as regards their effect on the cross sectional reduction as a percentage. The height of the deposits … |
||
|
|
Nov 19, 2004 Inclinometers, also called gradient measurement instruments, are utilised in combination with the sewer TV inspection for determining the gradient of the individual pipes or the section of the sewer (Abschnitt 4.3.2.1). The core piece of such an instrument is generally a gravity sensor with a control loop for torque compensation [Stein89g]. The measurement signal is a direct current, which is proportional to the sense of the gradient of inclination … |
||
|
|
Nov 19, 2004 (Image: Principle of the pressure measuring hose levelling device with reference to [Colli83] [Image: S&P GmbH]) The pressure measuring hose levelling instrument was developed especially for determining the vertical position (gradient, deflection, displacement) of non-man-accessible pipelines [Colli83] [NN86d]. A hose end is connected to a fixed level device containing a free fluid level as reference height. At the other end of the hose there is situated … |
||
|
|
Feb 16, 2011 (Image: Measuring arrangement for determining the directional deviation by means of laser and hole plate [NN86d]) The construction laser used for pipe laying can also be used to measure the position of existing straight drains and sewers in both the horizontal and vertical directions. For this purpose, the laser is positioned at the end of a section of the sewer, e.g. in an access manhole, and is first calibrated by means of a control board situated … |
||
|
|
Nov 19, 2004 Positional deviations in sewers can occur due to numerous causes (Abschnitt 2.4.1) and their recognition presents a condition for the evaluation of the hydraulic capabilities as well as for the selection of a suitable rehabilitation procedure. In accessible sewers, the measurement of the horizontal and vertical positional deviations is carried out by means of well-known engineering measuring methods, e.g. by means of the theodolite. In non-man-accessible … |
||
|
|
Nov 19, 2004 Rehabilitation and Maintenance of Drains and Sewers Profile Measurement (Displacement, Deformation, Internal Corrosion and Wear) Calibration measuring apparatus are pulled through the pipe or are moved forwards under the pressure of the conveying medium and make possible, by means of spring contacts evenly distributed around the circumference, the acquisition of ovalities, buckling, alterations of wall thicknesses, welding beads, deposits, etc. For flexible pipes, however, this is valid only on the assumption of a vertically symmetrical and elliptical deformation figure in … |
1158 search results:
