NL2004027C2 - System and method for detecting a water leak in a constructional wall or floor of a submerged excavation. - Google Patents

Description

System and method for detecting a water leak in a constructional wall or floor of a submerged excavation

The invention relates to a method and a system for detecting a water leak in a constructional wall or floor of a submerged excavation. The constructional wall may be of any known type, such as MT-piles, sheet piles, concrete piles or walls, 5 combinations thereof or any other type of wall. The floor can be of different construction, such as concrete, grout, an impermeable ground layer, etc.

Whenever a construction is established that in part requires the establishment of a constructional wall or floor by 10 means of excavating the ground under water, this constructional wall or floor usually suffers from the problem that leakages may occur that may be detrimental to the stability of the construction, or the stability of existing buildings in the vicinity of the construction. In terms of both a human and a financial per-15 spective the consequences of these leakages and the resulting stability problems are huge. In the prior art possible leakages are detected by using piezometers around the excavation, or by divers going down into the excavation searching for water leaks in the constructional wall or floor. Because underwater vision 20 in the excavation is usually very poor, the leakages are most commonly hard to find, and the divers work is therefore laborious and very expensive and in the end ineffective.

It is an object of the invention to provide a system and method for detecting a water leak in a constructional wall 25 or floor of a submerged excavation, which is less laborious and less costly, and which is reliable and versatile in its application .

To this end the method and the system of the invention are characterized by one or more of the appended claims.

30 One of the aspects of the invention is that the system comprises a first measuring organ which is arranged to detect a water flow from the outside to the inside of the excavation, and second position measurement means for measuring the position of the first measuring organ with reference to the constructional 35 wall or floor. With this system it is suitably possible to detect a water leak in a constructional wall or floor of a submerged excavation, by employing the measuring organ for detection of the water flow from the outside to the inside of the ex- 2 cavation, whereby the position of the first measuring organ with reference to the constructional wall or floor is registered and used for establishing the position where exactly the water leakage in the constructional wall or floor occurs.

5 A further aspect of the invention is the inventive thought to embody the first measuring organ with a sensor for detection of infrared radiation. The water flow from the outside to the inside of the excavation can then be detected with this sensor for detection of infrared radiation, which is quite in-10 genious and far from obvious if one considers that infrared radiation is strongly absorbed by water. The inventors have however found that it is possible to measure infrared radiation underwater and that measuring infrared radiation is a very suitable means of detecting where subsurface water leakages in a 15 wall or floor construction of a submerged excavation occur. This aspect of the invention is based on the insight that the water originating from the groundwater table outside of the excavation usually has a different temperature than the water inside the excavation. When the water pressure outside of the excavation is 20 higher than inside the excavation, a leakage will then result in a partial area of the water inside of the excavation getting a (slightly) different temperature than the water immediately surrounding it. By measuring this temperature difference it is possible to detect leakages.

25 Advantageously the sensor is comprised in a water- impermeable housing, and said housing is provided with a window that is permeable for infrared radiation, whereby the sensor is placed behind the window. The housing can then simply be submerged in order to detect a profile of infrared radiation at a 30 region of interest of the constructional wall or floor. This profile is preferably registered so as to make possible that it may be processed at a different time that it is monitored. For this purpose it is advantageous that the sensor is connected or connectable to processing means for registration of a profile of 35 infrared radiation at a region of interest of the constructional wall or floor.

Beneficially the processing means comprise a memory and/or a computer. This allows that the profile of infrared radiation is registered in this memory and/or the computer. It is 40 of course possible that the memory and/or the computer are placed distant from the sensor and are connected through wire or 3 through a radio connection. According to the invention is is however preferred that the processing means are provided in the housing, making it possible to provide real-time processing with an easy manageable system.

5 Still another aspect of the invention is that the first measuring organ is suspended from a lifting device such as a movable crane, whereby the position of the lifting device in a horizontal plane is registered by the second position measuring means. It is then further desirable that the first measuring or-10 gan is suspended from the lifting device at a pre-established vertical height, whereby said height is also registered by the second position measuring means. This system can then very effectively be used for searching the region of interest of the constructional wall or floor on the occurrence of a water leak 15 by moving the first measuring organ along said region, whereby the position of the first measuring organ in x-, y-, and z- direction is registered and used for establishing at which exact location of the constructional wall or floor a leakage occurs. For reliable measurement results it is preferred that the first 20 measuring organ is moved along the region of interest of the constructional wall or floor at a distance in the range 0-30 cm, preferably in the range 5-10 cm. In order to avoid turbulences in the water, the operating speed of the measuring device must not exceed a couple of centimeters per second. For the same rea-25 son, building activities in the excavation should be suspended during the measurement of leakages.

The invention will hereinafter be further elucidated with reference to the drawing of an exemplary embodiment of the system of the invention and its use for detection of a water 30 leakage in a constructional wall or floor of a submerged excavation .

In the drawing: -figure 1 shows part of the system of the invention; and 35 -figure 2 shows in a side view the system of the inven tion applied in a submerged excavation for detection of a water leakage in one of the walls of said excavation.

Whenever in the figures the same reference numerals are applied, these numerals refer to the same parts.

40 Referring first to figure 1 showing part of the system of the invention for detecting a water leak in a constructional 4 wall or floor of a submerged excavation, being a water-impermeable housing 1, whereby said housing 1 is provided with a window 2 that is permeable for infrared radiation, and whereby a sensor (not shown) for detection of infrared radiation is placed 5 in the housing 1 behind the window 2. Said sensor is connected or connectable to processing means for registration of a profile of infrared radiation at a region of interest 4 of a constructional wall 3 or floor 7 as shown in figure 2. It is feasible that said processing means comprising a memory and/or a computer 10 are provided in the housing 1 for immediate processing of data pertaining to the registered infrared radiation along the region of interest 4 of the constructional wall 3 or floor 7.

As the example of figure 2 further shows the housing 1 with the (not shown) sensor contained therein is suspended from 15 a lifting device such as the shown movable crane 5, whereby the position of the crane 5 in a horizontal plane is registered by a (also not shown) second position measuring means. The manner in which this may be realized is well known to the person skilled in the art and need not be shown herein. It is then also desir-20 able that the housing 1 with the sensor contained therein can be selected to be suspended from the movable crane 5 at a pre-established vertical height, whereby said height is also registered by the (not shown) second position measuring means. Accordingly the region of interest 4 of the constructional wall 3 25 or floor 7 can be searched for a water leak by moving the housing 1 with the sensor contained therein along said region 4, whereby the position of the housing 1 and the sensor in x-, y-, and z- direction is registered.

The invention thus provides effective means for detec-30 tion of a possible leakage in the constructional wall 3 or floor 7 of an excavation in the ground, wherein a water flow symbolized by the arrows 6 from the outside to the inside of the exca vation is detected, using a sensor for detection of infrared radiation. It is preferred that the housing 1 with the sensor con-35 tained therein is moved along the region of interest 4 of the constructional wall 3 or floor 7 at a distance in the range 0-30 cm, preferably in the range 5-10 cm.

In this method a profile of infrared radiation at a region of interest 4 of the constructional wall 3 or floor 7 is 40 registered, for instance in a memory and/or a computer, which may further be immediately or with delay processed in order to 5 enable an analyst to discover where a possible leakage in the constructional wall 3 or floor 7 may be present.

Claims (14)

A system for detecting a water leak in a construction wall (3) or floor (7) of a sunken building pit, characterized in that it comprises a first measuring device which is adapted to detect a water flow from outside 5 to inside building pit, and second position measuring means for measuring the position of the first measuring member with respect to the construction wall (3) or floor (7). 2. System as claimed in claim 1, characterized in that the first measuring element comprises a sensor for detection of infrared radiation. A system according to claim 1 or 2, characterized in that the sensor is accommodated in a watertight housing (1), and in that said housing (1) is provided with a window (2) which is permeable to infrared radiation, the sensor is placed behind the window (2). 4. System as claimed in any of the foregoing claims, characterized in that the sensor is coupled or connectable with processing means for recording a profile of infrared radiation in an examination area (4) of the construction wall (3) or floor (7) ). System according to claim 4, characterized in that the processing means comprise a memory and / or a computer. System according to claim 4 or 5, characterized in that the processing means are provided in the housing (1). A system according to any one of the preceding claims, characterized in that the first measuring device is suspended from a lifting device (5), the position of the lifting device being recorded in a horizontal plane by the second position-measuring means. A system according to claim 7, characterized in that the first measuring device is suspended from the lifting device (5) at a predetermined vertical height, said height being picked up by the second position measuring means. 9. Method for detecting a water leak in a construction wall or floor of a sunken building pit, characterized in that a water flow from the outside to the inside of the building pit is detected with a first measuring device, and that the position of the first measuring device with respect to the construction wall (3) or floor (7) is included. 10. Method according to claim 9, characterized in that the water flow from the outside to the inside of the building pit is detected with a sensor for detecting infrared radiation. Method according to claim 9 or 10, characterized in that a profile of infrared radiation is recorded in an examination area (4) of the construction wall (3) or floor (7). Method according to claim 11, characterized in that the profile of an infrared radiation is registered in a memory and / or a computer. 13. Method according to any of claims 9-12, characterized in that the examination area (4) of the construction wall (3) or floor (7) is detected for water leakage by moving the first measuring device along said area (4) wherein the position of the first measuring device in the x, y, and z directions is recorded. A method according to claim 13, characterized in that the first measuring device is moved along the examination area (4) of the construction wall (3) or floor (7) at a distance in the range 0-30 cm, preferably in the range 5-10 cm.