GB2043895A

GB2043895A - Terrestrial Settlement Probe Unit

Info

Publication number: GB2043895A
Application number: GB7934132A
Authority: GB
Original assignee: SOIL INSTRUMENTS Ltd
Current assignee: SOIL INSTRUMENTS Ltd
Priority date: 1978-10-04
Filing date: 1979-10-02
Publication date: 1980-10-08
Also published as: GB2043895B

Abstract

A probe unit for determination of settlement within a terrestrial matrix by a method in which the probe unit is advanced through a tube which has already installed within the ground or foundation structure, for example during construction, the probe unit being used to determine any change in the elevation of defined points along the length of the tube. The probe comprises a body 2 housing an elongate distensible bladder 8 disposed about a rigid tube support 5, the support affording communication 6 for a liquid medium between a first connector 9 and the interior of the bladder, a cavity 10 being provided between the bladder and the body for a pressure gas medium and connected through a duct with a second connector 13, the probe unit in use being connected by the first connector to a flexible tube supplying the liquid medium to the bladder and by the second connector to a further flexible tube supplying the gaseous medium. <IMAGE>

Description

SPECIFICATION Terrestrial Settlement Probe Unit This invention relates to a probe unit for determination of settlement within a terrestrial matrix by a method in which the probe unit is advanced through a tube which has already installed within the ground or foundation structure, for example during construction, the probe unit being used to determine any change in the elevation of defined points along the length of the tube.

According to this invention a probe unit for the above purpose comprises a body housing an elongate distensible bladder disposed about a rigid tube support, the support affording communication for a liquid medium between a first connector and the interior of the bladder, a cavity being provided between the bladder and the body for a pressure gas medium and connected through a duct with a second connector, the probe unit in use being connected by the first connector to a flexible tube supplying the liquid medium to the bladder and by the second connector to a further flexible tube supplying the gaseous medium.

With such an arrangement the bladder may first be filled with the liquid medium, for example ethanol or water, and thereafter a predefined quantity of said liquid removed so that the bladder is in a slack state allowing it to give or take the liquid. The pressure gas medium, for example nitrogen, is applied to the cavity through the second tube and also pressurises the liquid at the remote reading station to which the probe is connected via the tubes. As the probe follows the installed tube profile the head changes and this may be observed on a manometer transducer or the like at the reading station.

In this probe the pressurisation on the outside of the bladder isolates the device from the effects of external atmospheric pressure changes which can significantly affect accuracy and also the effect of entrained air is reduced. Migration of air along the fluid lines is also reduced. The construction also offers a robust reliable unit of simple construction. The invention also embraces the method of determining settlement using the probe unit.

An embodiment is shown in the drawings as an example and further describing the probe unit and system of the invention, in the drawings: Figure 1 shows the principal parts of a probe unit, and Figure 2 shows a circuit of a system of measurement using the probe.

Referring to Figure 1, the probe unit has a body 1 formed from a main core part 2, a forward housing 3 and rearward housing 4. The housings 3 and 4 are screw-thread connected to the core 2.

The forward end of a core 2 carries a rigid support tube 5 around which a distensible rubber bladder B is located. The tube 5 includes a series of perforations 6 and provides communication through duct 7 with a first connector 8 for coupling with a flexible plastics tube 9. An annular cavity 10 exists between the housing 3 and tube 5 and this communicates through duct 11 with a second connector 12 for coupling with a further flexible plastics tube 1 3.

In use the bladder is filled with ethanol, together with tube 9 and duct 7, with care being taken to exclude air as far as possible. Pressure is applied to the outside of the bladder via tube 1 3 and normally nitrogen gas is to be preferred but a second liquid could be used. A predetermined quantity of the ethanol is then removed to ensure that the bladder may be taken-up or yield ethanol during use.

Figure 2 shows a simplified circuit with the probe unit 1 containing the bladder B and connected through the flexible tubes 9 and 1 3 to the measuring station 5. The probe 1 will, in practice, be intoduced into an existing tube T provided within the building structure for the purpose of measuring the elevation at various points therealong.

The tube 9 may be connected to a reservoir R of ethanol to fill the system via a valve V, and a syringe N provides means to withdraw a measured quantity of fluid from the bladder so that room for expansion within the cavity 10 is allowed for. After removal of this quantity the valve is used to connect the bladder to manometer M which provides an indication of the level of the probe at any point during travel along the tube. The system is pressurised from a source of pressure gas P which is taken to the probe 1 through the tube 1 3. The pressure is typically 1 Bar and a gauge G may be inciuded.

In the normal condition the bladder will contain ethanol but in a slack state and will fill or empty according to the height change from a datum level. The system may use mercury to replace the ethanol and then a pressure gauge may be used due to the higher pressure change with height.

Claims

1. A probe unit for determination of terrestrial settlement comprising a body housing an elongate distensible bladder disposed about a rigid tube support, the support affording communication for a liquid medium between a first connector and the interior of the bladder, a cavity being provided between the bladder and the body for a pressure gas medium and connected through a duct with a second connector, the probe unit in use being connected by the first connector to a flexible tube supplying the liquid medium to the bladder and by the second connector to a further flexible tube supplying the gaseous medium.

2. A probe according to Claim 1, wherein the body comprises a core carrying the rigid tube support at one end and first and second connections at the other end, a housing at one end of the core extending coaxially therewith and over the rigid tube to enclose same with an annular space forming the cavity allowing limited expansion of the bladder.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Terrestrial Settlement Probe Unit This invention relates to a probe unit for determination of settlement within a terrestrial matrix by a method in which the probe unit is advanced through a tube which has already installed within the ground or foundation structure, for example during construction, the probe unit being used to determine any change in the elevation of defined points along the length of the tube. According to this invention a probe unit for the above purpose comprises a body housing an elongate distensible bladder disposed about a rigid tube support, the support affording communication for a liquid medium between a first connector and the interior of the bladder, a cavity being provided between the bladder and the body for a pressure gas medium and connected through a duct with a second connector, the probe unit in use being connected by the first connector to a flexible tube supplying the liquid medium to the bladder and by the second connector to a further flexible tube supplying the gaseous medium. With such an arrangement the bladder may first be filled with the liquid medium, for example ethanol or water, and thereafter a predefined quantity of said liquid removed so that the bladder is in a slack state allowing it to give or take the liquid. The pressure gas medium, for example nitrogen, is applied to the cavity through the second tube and also pressurises the liquid at the remote reading station to which the probe is connected via the tubes. As the probe follows the installed tube profile the head changes and this may be observed on a manometer transducer or the like at the reading station. In this probe the pressurisation on the outside of the bladder isolates the device from the effects of external atmospheric pressure changes which can significantly affect accuracy and also the effect of entrained air is reduced. Migration of air along the fluid lines is also reduced. The construction also offers a robust reliable unit of simple construction. The invention also embraces the method of determining settlement using the probe unit. An embodiment is shown in the drawings as an example and further describing the probe unit and system of the invention, in the drawings: Figure 1 shows the principal parts of a probe unit, and Figure 2 shows a circuit of a system of measurement using the probe. Referring to Figure 1, the probe unit has a body 1 formed from a main core part 2, a forward housing 3 and rearward housing 4. The housings 3 and 4 are screw-thread connected to the core 2. The forward end of a core 2 carries a rigid support tube 5 around which a distensible rubber bladder B is located. The tube 5 includes a series of perforations 6 and provides communication through duct 7 with a first connector 8 for coupling with a flexible plastics tube 9. An annular cavity 10 exists between the housing 3 and tube 5 and this communicates through duct 11 with a second connector 12 for coupling with a further flexible plastics tube 1 3. In use the bladder is filled with ethanol, together with tube 9 and duct 7, with care being taken to exclude air as far as possible. Pressure is applied to the outside of the bladder via tube 1 3 and normally nitrogen gas is to be preferred but a second liquid could be used. A predetermined quantity of the ethanol is then removed to ensure that the bladder may be taken-up or yield ethanol during use. Figure 2 shows a simplified circuit with the probe unit 1 containing the bladder B and connected through the flexible tubes 9 and 1 3 to the measuring station 5. The probe 1 will, in practice, be intoduced into an existing tube T provided within the building structure for the purpose of measuring the elevation at various points therealong. The tube 9 may be connected to a reservoir R of ethanol to fill the system via a valve V, and a syringe N provides means to withdraw a measured quantity of fluid from the bladder so that room for expansion within the cavity 10 is allowed for. After removal of this quantity the valve is used to connect the bladder to manometer M which provides an indication of the level of the probe at any point during travel along the tube. The system is pressurised from a source of pressure gas P which is taken to the probe 1 through the tube 1 3. The pressure is typically 1 Bar and a gauge G may be inciuded. In the normal condition the bladder will contain ethanol but in a slack state and will fill or empty according to the height change from a datum level. The system may use mercury to replace the ethanol and then a pressure gauge may be used due to the higher pressure change with height. Claims

3. A probe according to Claim 2, wherein the rigid tube support includes a plurality of perforations affording passage for the liquid medium from the first connector to the interior of the bladder.

4. A probe according to Claim 2 or 3, wherein the core includes a duct connecting the annular space with the second connector.

5. A probe according to any one of Claims 2 to 4, wherein a housing is provided at the other end of the core, the housing extending over the connectors and including passages for the flexible tubing.

6. A probe in accordance with any one of Claims 2 to 5, wherein the, or each, housing is screw connected with the core.

7. A method for determination of settlement within a terrestrial matrix in which a probe unit in accordance with any one of Claims 1 to 6 is advanced through a tube which has already installed within the ground or foundation structure, for example during construction, the probe unit being used to determine any change in the elevation of defined points along the length of the tube, by supplying a constant pressure through the second connector, and measuring the pressure changes occurring in the liquid medium.

8. A probe unit for the purpose herein set forth substantially as herein described with reference to Figures 1 and 2 of the accompanying drawings.

1 0. The method for determination of settlement carried out substantially as herein described with reference to the accompanying drawings.