Methods and apparatus for monitoring structures

Abstract

A system for monitoring a foundation includes a plurality of sensors disposed in a tube. Each sensor is immersed in a dielectric fluid in the tube. A sensor head is attached to an end of the tube. At least one sensor in the sensor head is located above a level of the dielectric fluid. The tube may be positioned within the foundation and / or attached to a perimeter of the foundation. Each sensor in the tube is associated with a corresponding section of the foundation. Pressure measurements made by each sensor in the tube are used to determine a change in elevation of each section of the foundation.

Description

METHODS AND APPARATUS FOR MONITORING STRUCTURESCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is an International Patent Application under the Patent Cooperation Treaty, and claims priority to and the benefit of U.S. Provisional Patent Application Serial No. 63 / 610,063 filed December 14, 2023 and titled Methods and Apparatus for Monitoring Structures, the disclosure of which is incorporated herein in its entirety by this reference.BACKGROUNDField

[0002] The present disclosure generally relates to methods, systems, and apparatus for monitoring the elevation and movement of a structure.Description of the Related Art

[0003] Movements of the ground can cause damage to foundations of structures built thereon. Early detection of damage, or of conditions likely to cause damage, can beneficially impact repair costs. The repair costs may be minor with the timely implementation of a change to a foundation maintenance program before significant damage occurs. However, if left undetected, or if ignored, foundation damage can render a structure unsafe, uninhabitable, or unsuitable for intended uses, and repair costs may be substantial.

[0004] Effective early detection of foundation problems may be facilitated by the acquisition of competent measurements of the foundation itself. For example, a sensor may be moved within a conduit in a foundation, and may take readings of hydrostatic head of a surrounding fluid at various locations in the foundation, each reading indicative of the elevation of the conduit — and thus the foundation — at each location. However, such techniques are cumbersome, and are subject to error due to temperature effects and physical phenomena such as gas breakout / dissolution in the surrounding fluid. Furthermore, measurements taken at lengthy time intervals may not reveal the true extent of foundation movement over time.

[0005] Thus, there is a need for improved processes that facilitate efficient, effective, and accurate monitoring of foundations and other structures.SUMMARY

[0006] The present disclosure generally relates to systems, apparatus, and methods for the evaluation of foundations. In one embodiment, a system for monitoring a foundation includes a tube containing a plurality of first sensors. A sensor head includes a first compartment separated from a second compartment, the sensor head being coupled to the tube at the first compartment. A second sensor is disposed in the first compartment. A controller is disposed in the sensor head. The controller is communicatively coupled to the plurality of first sensors and to the second sensor. A dielectric liquid is in the tube and the first compartment. The dielectric liquid covers each of the first sensors.

[0007] In another embodiment, a method of monitoring a foundation includes coupling a tube to the foundation. The tube contains a plurality of first sensors. Each first sensor is associated with a corresponding section of the foundation. The method includes positioning a level of a dielectric liquid above a second sensor in a sensor head coupled to the tube. The method includes taking first pressure measurements using each sensor of the plurality of first sensors and the second sensor. The method includes obtaining first atmospheric pressure information corresponding to the first pressure measurements. The method includes determining, from the first pressure measurements and the first atmospheric pressure information, a first elevation of each sensor of the plurality of first sensors relative to the second sensor. The method includes taking second pressure measurements using each sensor of the plurality of first sensors and the second sensor. The method includes obtaining second atmospheric pressure information corresponding to the second pressure measurements. The method includes determining, from the second pressure measurements and the second atmospheric pressure information, a second elevation of each sensor of the plurality of first sensors relative to the second sensor. The method includes determining a difference between the first elevation and the second elevation of each sensor of the plurality of first sensors, and determining a change in elevation of each section of the foundation corresponding to each sensor of the plurality of first sensors.

[0008] In another embodiment, a method of monitoring a foundation includes coupling a first plurality of sensors to a first portion of the foundation, and coupling a second plurality of sensors to a second portion of the foundation. The method includes taking afirst set of pressure measurements using the first plurality of sensors. The method includes obtaining a plurality of first atmospheric pressure measurements corresponding to the first set of pressure measurements. The method includes taking a second set of pressure measurements using the second plurality of sensors. The method includes obtaining a plurality of second atmospheric pressure measurements corresponding to the second set of pressure measurements. The method includes identifying a first time period of the first atmospheric pressure measurements that correlates to a second time period of the second atmospheric pressure measurements. The method includes identifying one or more first data points of the first set of pressure measurements taken during the first time period, and identifying one or more second data points of the second set of pressure measurements taken during the second time period. The method includes determining, from the one or more first data points, an elevation profile of the first portion of the foundation. The method further includes determining, from the one or more second data points, an elevation profile of the second portion of the foundation.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of the scope of the disclosure, as the disclosure may admit to other equally effective embodiments.

[0010] Figure 1 schematically illustrates a foundation monitoring system.

[0011] Figure 2 is a schematic combined elevation and cross-sectional view of selected components of the foundation monitoring system of Figure 1.

[0012] Figure 3 is a schematic cross-sectional view of a portion of the apparatus of Figure 2.

[0013] Figure 4 is a partial cross-section that schematically illustrates a portion of the foundation monitoring system of Figure 1 .

[0014] Figure 5 schematically illustrates the apparatus of Figure 4 during a calibration operation.

[0015] Figure 6 schematically illustrates the foundation monitoring system of Figure 1 coupled to a foundation.

[0016] Figures 7A to 7D schematically illustrate exemplary ways of attaching the foundation monitoring system of Figure 1 to a foundation.

[0017] Figures 8A to 8C schematically illustrate exemplary communication links for installations that include multiple foundation monitoring systems of Figure 1.

[0018] Figure 9A schematically depicts an installation of the foundation monitoring system of Figure 1 .

[0019] Figure 9B schematically depicts the installation of Figure 9A at a later time.

[0020] Figure 9C presents an example graph of data pertaining to the installation ofFigure 9A.

[0021] Figure 9D presents an example graph of data pertaining to the installation of Figure 9B.

[0022] Figures 9E and 9F present example graphs related to the graphs in Figures 9C and 9D.

[0023] Figure 10 is a flowchart of a method of monitoring a foundation.

[0024] Figures 11A and 11 B schematically illustrate an exemplary method of monitoring a foundation.

[0025] Figure 11 C presents an example graph of sensor elevations relative to a reference point over time.

[0026] Figure 12 is a flowchart of a method of monitoring a foundation.

[0027] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It iscontemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.DETAILED DESCRIPTION

[0028] The present disclosure concerns systems, apparatus, and methods for the evaluation of a foundation and / or a structure built on a foundation. Example structures include, without limitation, buildings, dams, walls, tunnels, bridges, storage tanks, bulkheads, wind turbines, or any other construction upon the Earth’s surface. The evaluation may be undertaken for one or more purpose, such as, without limitation, an assessment of suitability for occupancy, identification of maintenance needs, success of completed repairs, independent confirmation of construction quality, prediction of future foundation issues, confirmation of engineering calculations, rapid testing of foundation performance evaluation during real estate transactions, or the creation of an actuarial database for the purpose of creating an insurance product. Other purposes for such evaluation are also contemplated, including, without limitation, maintenance interval prediction, repair evaluation, performance evaluation of contractors, actuarial data and insurance, intentional stress testing of foundation designs, and comparative performance analysis of foundation designs.

[0029] Figure 1 schematically illustrates a foundation monitoring system 100. The foundation monitoring system 100 includes a tube 160 coupled to a sensor head 110. A guide shoe 164 is located at an end of the tube 160. In some embodiments, an exterior surface of the guide shoe 164 is rounded or chamfered. In some embodiments, the guide shoe 164 is vented to permit fluids to enter the tube 160 but not exit the tube 160. In some embodiments, the guide shoe 164 is vented to permit fluids to exit the tube 160 but not enter the tube 160. In some embodiments, the guide shoe 164 is vented to permit fluids to enter and exit the tube 160. In some embodiments, the guide shoe 164 is not vented, and passage of fluids into and out of the tube 160 via the guide shoe 164 is prevented.

[0030] The tube 160 contains a sensor fluid 190, such as a single phase fluid, such as a liquid. The sensor fluid 190 is a dielectric fluid. Exemplary dielectric fluids include distilled water, natural or synthetic dielectric oils (such as mineral oils), transformer oils, fluids used in electric discharge machining, and the like.

[0031] A plurality of sensors 170 is installed in the tube 160. The sensor fluid 190 fills the tube 160 such that each sensor 170 within the tube 160 is immersed in the sensor fluid 190. Each sensor 170 measures and transmits data representative of a temperature and a pressure of the sensor fluid 190 surrounding the sensor 170 in the tube 160. The sensors 170 are spaced from one another along the tube 160. In some embodiments, the sensors 170 within the tube 160 are spaced at regular intervals along the tube 160. For example, the sensors 170 may be spaced about ten feet (about 3 m) apart. Additionally, or alternatively, some sensors 170 may be spaced closer together along the tube 160, and other sensors 170 may be spaced further apart along the tube 160.

[0032] Each sensor 170 within the tube 160 is connected to wiring 162 that is routed within the tube 160 from each sensor 170 to the sensor head 110. In some embodiments, the wiring 162 connected to each corresponding sensor 170 may be discrete from other wiring 162 connected to another sensor 170. In some embodiments, each sensor 170 is coupled to common wiring 162. In some embodiments, the wiring 162 for individual sensors 170 may be bundled together as an integrated unit. In an example, wiring 162 connected to a first sensor 170 may be attached to wiring 162 connected to a second sensor 170 by one or more clips, cable ties, encapsulations, or sheaths.

[0033] The wiring 162 conveys electrical power to each sensor 170 and / or facilitates telemetry of data from each sensor 170 to the sensor head 110. In some embodiments, one or more sensor 170 may be powered by a battery local to the one or more sensor 170 instead of, or in addition to, being powered via the wiring 162. In some embodiments, data from one or more sensor 170 may be telemetered wirelessly. In some embodiments the wiring 162 may include an optical fiber line for the telemetry of data from one or more sensor 170. In some embodiments, command signals may be sent to one or more sensor 170 via the wiring 162 and / or wirelessly.

[0034] The sensor head 110 is coupled to the tube 160 at the end of the tube 160 opposite to the guide shoe 164. The sensor head 110 contains a controller 150. The controller 150 includes a central processing unit (CPU), a memory containing instructions, and support circuits for the CPU. The memory, or non-transitory computer readable medium, is one or more of a readily available memory such as random access memory (RAM), read only memory (ROM), floppy disk, hard disk, flash drive, or any other form of digital storage, local or remote. The support circuits are coupled to the CPU for supportingthe CPU. The support circuits include cache, power supplies, clock circuits, input / output circuitry and subsystems, and the like. Operations and operating parameters are stored in the memory as a software routine that is executed or invoked to configure the controller 150 into a specific purpose controller to control the operations of the foundation monitoring system 100. The controller 150 is configured to conduct one or more of the operations described herein. The instructions stored on the memory, when executed, cause one or more of the operations described herein to be conducted.

[0035] In some embodiments, the controller 150 includes, or is coupled to, a communication chip. In some embodiments, the controller 150 includes, or is coupled to, a transmitter / receiver that facilitates communication with other devices, such as a base station or other controllers of other foundation monitoring systems.

[0036] The wiring 162 in the tube 160 extends into the sensor head 110, and is coupled to the controller 150. The controller 150 includes, or is coupled to, sensors 152 and 154 in the sensor head 110. Each sensor 152, 154 measures and transmits data representative of a temperature and a pressure of the fluid surrounding the respective sensor 152, 154 in the sensor head 110. The sensor fluid 190 is present in the tube 160 and the sensor head 110. During operation of the foundation monitoring system 100, a level 192 of the sensor fluid 190 in the sensor head 110 is between the sensor 152 and the sensor 154 such that the sensor 154 is immersed in the sensor fluid 190. The sensor 152 measures atmospheric pressure and temperature within the sensor head 110. In some embodiments, sensor 152 may be omitted. In an example, local atmospheric pressure data, such as from a weather station, may be used to estimate the atmospheric pressure at the location of the sensor head 110. In some embodiments, sensor 154 may be omitted.

[0037] Figure 2 is a schematic combined elevation and cross-sectional view that schematically illustrates a sensor 170 in the tube 160. Figure 3 is a schematic cross- sectional view through the tube 160 of Figure 2.

[0038] In some embodiments, as illustrated, sensor 170 includes a printed circuit board 172 with a surface 174 on which are attached one or more connectors 176 for attaching to wiring 162, one or more sensor chips 178, and one or more communication chips 180. In some embodiments, the sensor chip 178, and the one or morecommunication chips 180 are integrated into a microprocessor. The one or more sensor chips 178 are configured to measure a pressure and / or a temperature of the ambient environment at the sensor 170. In some embodiments, the sensor 170 includes additional circuitry (such as an additional chip, an accelerometer, an inclinometer, or the like) for measuring additional parameters, such as motion, vibration, time, etc. In some embodiments, the sensor 170 and / or the one or more sensor chips 178 include a memory. In some embodiments, the sensor 170 includes an identification device, such as an RFID tag.

[0039] The one or more communication chips 180 are configured to transmit data measured by the one or more sensor chip 178 and any additional circuitry. The one or more communication chips 180 transmit such data via the connector 176 and associated wiring 162. Additionally, or alternatively, in some embodiments the one or more communication chips 180 transmit at least a portion of such data wirelessly.

[0040] In some embodiments, each sensor 170 is coupled to a payout line 166 that facilitates insertion of each sensor 170 into, and removal of each sensor 170 from, the tube 160. As illustrated, in some embodiments a portion 168 of the payout line 166 near to the sensor 170 is contorted into a “u” shape, or the like. As shown in Figure 3, in some embodiments the sensor 170 is attached to the payout line 166 by a centralizer 182 and a retainer 184 such that the contorted portion 168 of the payout line 166 is oriented along an axis 186 that is substantially perpendicular to the surface 174 of the printed circuit board 172 of the sensor 170. In an example, the axis 186 is 85 to 90 degrees, such as 86 to 90 degrees, or 88 to 90 degrees from the surface 174 of the printed circuit board 172. The contorted portion 168 of the payout line 166 enables the payout line 166 to transfer an axial force to the sensor 170 along the tube 160.

[0041] Additionally, the centralizer 182 facilitates the placement of the sensor chip 178 substantially at the radial center of the tube 160, such as within a half inch (1.3 cm), within a quarter inch (0.6 cm), or within an eighth of an inch (0.3 cm) of the radial center of the tube 160. In some embodiments, the contorted portion 168 of the payout line 166 bears against one portion of a sidewall of the tube 160 and the centralizer 182 and / or retainer 184 bear(s) against one or more other portions of the sidewall of the tube 160 in order to facilitate placement of the sensor chip 178 at or near to the radial center of the tube 160. In some embodiments, the contorted portion 168 of the payout line 166, the centralizer182 and / or the retainer 184 maintain placement of the sensor chip 178 at or near to the radial center of the tube 160 regardless of the rotational orientation of the printed circuit board 172 within the tube 160.

[0042] In some embodiments, the contorted portion 168 of the payout line 166 is omitted, such that the centralizer 182 and / or retainer 184 alone maintain placement of the sensor chip 178 at or near to the radial center of the tube 160. In some embodiments, the centralizer 182 is omitted. In some of such embodiments, the retainer 184 attaches the payout line 166 to the printed circuit board 172. Additionally, the retainer 1841 printed circuit board 172 may be self-centralizing.

[0043] In some embodiments, the payout line 166 may be omitted. In some embodiments, the wiring 162 facilitates installation of the sensors 170 into the tube 160.

[0044] In some embodiments, the sensor 170 is configured such that the sensor chip 178 is not placed at or near the radial center of the tube 160. For example, the sensor 170 may include an attachment and / or retainer 184 configured to offset the sensor chip 178 from the radial center of the tube 160. Such an example may include the use of a weight attached to the sensor so that the rotational orientation of the sensor 170 is maintained relatively constant by the Earth’s gravity. Alternatively, a biasing element, such as a bow spring, may be attached to the sensor 170 in order to force the sensor 170 against the sidewall of the tube 160, thereby holding the sensor 170 rotationally in place.

[0045] In another example, the sensor 170 may be configured such that the sensor chip 178 may be positioned in a zone that includes the radial center of the tube 160 and includes a region surrounding the radial center of the tube 160.

[0046] In embodiments in which a sensor chip 178 of a sensor 170 is positioned at the radial center of a tube 160, it is contemplated that the elevation of the point of measurement of the sensor chip 178 remains at the radial center of the tube 160, and hence at the same elevation with respect to the tube 160, even if the sensor 170 is rotated within the tube 160. Therefore, even if the sensor 170 is rotated within the tube 160, such as during an interval between acquiring measurements from the sensor 170, each measurement is indicative of the elevation of the tube 160 itself with respect to the corresponding sensor head 110. Thus, in comparing measurements taken at different times, a change in the magnitude of the data values obtained from the sensor 170 canindicate that there has occurred a change in the elevation of the tube 160, and hence a change in the elevation of the section of the foundation to which the tube 160 is attached.

[0047] In embodiments in which a sensor chip 178 of a sensor 170 is positioned near to the radial center of a tube 160, it is contemplated that should the sensor 170 become rotated within the tube 160 between or during acquiring measurements, any error in later measurements due to a change in elevation of the point of measurement of the sensor chip 178 with respect to the tube 160 may be minor compared to other sources of inaccuracy, such as density variations of the sensor fluid 190 within the tube160.

[0048] Nevertheless, it is contemplated that after the tube 160 has been installed at a work location, the propensity is low for a sensor 170 to become rotated within a tube 160 between or during the acquisition of measurements from the sensor 170. Hence, the propensity is low for a change in elevation with respect to the tube 160 of the point of measurement of the sensor chip 178. Therefore, in embodiments in which a sensor chip 178 of a sensor 170 is positioned away from the radial center of a tube 160, it is contemplated that rotation of the sensor 170 between or during acquiring measurements would not be a root cause of error when comparing the measurements.

[0049] Figure 2 further depicts a payout distance 188 of the sensor 170 with respect to a reference point 196, such as a brick ledge on the foundation, the sensor 152, the sensor 154, the controller 150, or a specific datum of the sensor head 110. As illustrated, the payout distance 188 is representative of a distance of the sensor chip 178 of sensor 170 from the reference point 196. In some embodiments, the payout distance 188 is a distance measured along the tube 160. In some embodiments, the payout distance 188 is a lateral distance measured in a horizontal plane. The payout distance 188 refers to the location of the sensor 170 along the tube 160.

[0050] Figure 3 further depicts an elevation 194 of the sensor 170 with respect to the reference point 196. In some embodiments, the elevation 194 of the sensor 170 may be determined with respect to a datum different to the reference point 196, such as the sensor fluid level 192 in the sensor head 110. The elevation 194 is derived from a measurement of hydrostatic pressure of the sensor fluid 190 by the sensor chip 178. The hydrostatic pressure of the sensor fluid 190 is a function of the density of the sensor fluid 190. The density of the sensor fluid 190 is a function of the temperature of the sensorfluid 190. Measurements of temperature and pressure by the sensor chip 178 of each sensor 170 and the sensor 154 provide data from which the elevation 194 of each sensor 170 is derived. The elevation 194 is recorded for each sensor 170 corresponding to measurements obtained from each sensor 170 and sensor 154 over time.

[0051] During assembly, the tube 160 is filled with sensor fluid 190. In some embodiments, it is contemplated that the tube 160 is filled with sensor fluid 190 in a manner that removes air from the tube 160. For example, the sensor fluid 190 may be introduced into the tube 160 via a capillary line. In another example, the tube 160 is positioned at an incline to promote the escape of air during filling with sensor fluid 190. Additionally, or alternatively, a vacuum may be applied to the tube 160 to evacuate air while filling the tube 160 with sensor fluid 190. Furthermore, the tube 160 may be vibrated during and / or after introduction of the sensor fluid 190 in order to dislodge air bubbles so that the air bubbles can escape from the tube 160.

[0052] The location of each sensor 170 along the tube 160 is noted for future reference with respect to sections of a foundation to be monitored by corresponding sensors 170. In some embodiments, the location of each sensor 170 in the tube 160 is ascertained via an identification device (such as an RFID tag) included with each sensor 170. In an example, an operator uses a handheld reader to locate each identification device to confirm the identity (such as name or number) and location of each sensor 170. In some embodiments, the tube 160 is transparent, enabling an operator to visually locate each sensor 170. In some embodiments, the tube 160 is translucent such that a shadow of each sensor 170 is visible. In an example, an operator uses a flashlight to create the shadow of each sensor 170. As illustrated, in some embodiments, the sensor 170 includes a light source, such as an LED 181 . The LED 181 may be illuminated to indicate the location of the sensor 170 in the tube 160. In an example, light emitted by the LED is visible through the wall of the tube 160, such as in embodiments in which the tube 160 is made of a translucent material, such as a polymer. The LED 181 may be illuminated during installation and / or operation of foundation monitoring system 100 for correlating the location of the sensor 170 with a portion of the foundation. The identified location of each sensor 170 may be correlated with the corresponding payout distance 188 of each sensor 170.

[0053] Figure 4 is a partial cross-section that schematically illustrates the sensor head 110. The sensor head 110 includes a body 112 and a lid 114. A divider 116 is sealed against the body 112 by a seal 118, such as a gasket, an o-ring, or the like. The divider 116 separates the sensor head 110 into an upper compartment 120 and a lower compartment 122. The lower compartment 122 is sealed with respect an exterior of the sensor head 110 by the seal 118.

[0054] The lower compartment 122 contains the controller 150, the sensor 152, and the sensor 154. The controller 150 includes, or is coupled to, the sensor 152 and the sensor 154. The controller 150 is coupled to the wiring 162 extending from the tube 160. The tube 160 is coupled to the sensor head 110 at the lower compartment 122. The lower compartment 122 contains the sensor fluid 190 up to the sensor fluid level 192 between the sensor 152 and the sensor 154 such that the sensor 154 is immersed in the sensor fluid 190. In embodiments in which the sensor 154 is omitted, the sensor fluid level is below the sensor 152. In some of such embodiments, the sensor fluid level 192 is within the tube 160, below the sensor head 110, but above a sensor 170 in the tube 160.

[0055] The upper compartment 120 is exposed to atmospheric pressure, such as via a port in the lid 114. The sensor head 110 includes a vent 124. As illustrated, in some embodiments, the vent 124 is located in the divider 116, and fluidically couples the upper compartment 120 with the lower compartment 122. Additionally, or alternatively, in some embodiments, the vent 124 is located in a wall of the body 112, and directly fluidically couples the lower compartment 122 with an exterior of the sensor head 110. In some embodiments, a cap 126 on the vent 124 inhibits the passage of liquids and solids through the vent 124 into the lower compartment 122. A breather port 128 in the cap 126 facilitates the equalization of pressure between the upper compartment 120 and the lower compartment 122. Additionally, or alternatively, a filter or a diaphragm in the vent 124 facilitates the communication of atmospheric pressure to the lower compartment 122 while inhibiting the passage into the lower compartment 122 of moisture entrained in the air.

[0056] The upper compartment 120 contains a battery 132 that powers the controller 150, the sensor 152, and the sensor 154. In some embodiments, the battery 132 also powers the sensors 170 in the tube 160. In some embodiments, the battery 132 is rechargeable. In at least some of such embodiments, the battery 132 may be coupled toan external power supply, such as a solar panel 134, that facilitates recharging of the battery 132. In an example, as illustrated, the solar panel 134 may be located on an exterior of the sensor head 110, such as on the lid 114. Additionally, or alternatively, the external power supply may include a conventional electricity supply 138, such as a mains electricity supply. In some embodiments, the controller 150 is coupled directly to the external power supply. In some embodiments, the battery 132 serves as a back-up power supply to the external power supply. In some embodiments, the battery 132 may be omitted.

[0057] Figure 5 schematically illustrates the sensor head 110 during a calibration of the sensors 152, 154, 170. The lid 114 is omitted for clarity; the lid 114 may be removed for the performance of the calibration operation. The cap 126 is removed from the vent 124, and a gas source 142 is coupled to the vent 124, such as via a tube 144. The gas source 142 provides a gas, such as air or pure nitrogen. The gas is pressurized. Gas from the gas source 142 is fed into the lower compartment 122, which increases the pressure inside the lower compartment 122 with respect to the ambient pressure in the upper compartment 120 and external to the sensor head 110. The increased pressure in the lower compartment 122 is exerted on the sensor fluid 190, and is communicated by the sensor fluid 190 into the tube 160. It is contemplated that the sensor fluid level 192 may change as the pressure inside the lower compartment 122 increases. In an example, the increased pressure exerted on the sensor fluid 190 may cause the tube 160 to expand. Nevertheless, the sensor fluid level 192 is maintained above the sensor 154 (if present).

[0058] In the calibration operation, the sensors 152, 154, 170 take first measurements of pressure and temperature before the pressure within the lower compartment 122 is increased. In some embodiments, a first reference pressure measurement is taken by a reference sensor 146 that is independent of the sensors 152, 154, and 170. In an example, the reference sensor 146 is associated with the gas source 142. Then the pressure within the lower compartment 122 is increased, as described above. While the pressure within the lower compartment 122 is at an increased magnitude, the sensors 146, 152, 154, 170 take second measurements of pressure and temperature. Then the pressure within the lower compartment 122 is reduced and equalized with the ambient pressure external to the lower compartment 122. In an example, flow of gas from the gas source 142 is ceased, and a bleed valve at the gas source 142 or in the tube 144 is opened to fluidically couple the vent 124 to the atmosphere. Then the sensors 146, 152,154, 170 take third measurements of pressure and temperature. Then the sensors 152, 154, 170 are calibrated according to a comparison of the first, second, and third measurements of pressure and temperature recorded from each sensor 146, 152, 154, 170.

[0059] Figure 6 schematically illustrates examples of the foundation monitoring system 100 coupled to a foundation 322 of a structure 320. The structure 320 may be any structure, such as described above, that sits atop the foundation 322. As illustrated, in some embodiments, at least a portion of the foundation monitoring system 100 is coupled to the structure 320. In some examples, the entire foundation monitoring system 100 is coupled to the structure 320. However, in some embodiments, the entire foundation monitoring system 100 is coupled to the foundation 322. The foundation monitoring system 100 is represented by each of foundation monitoring system 100A and foundation monitoring system 100B. Foundation monitoring system 100A is coupled to portion 322A of the foundation 322. In some embodiments, the coupling is performed according to any of the methods described herein, such as with respect to Figures 7A to 7C. Foundation monitoring system 100B is coupled to portion 322B of the foundation 322. In some embodiments, the coupling is performed according to any of the methods described herein, such as with respect to Figure 7D. The sensor head 110 of each of foundation monitoring system 100A and foundation monitoring system 100B is attached to the structure 320, such as by a clamp, an adhesive, or a fastener (such as a screw). In some embodiments, a single foundation monitoring system 100 is coupled to the foundation 322. In some embodiments, two or more foundation monitoring systems 100 are coupled to the foundation 322.

[0060] In some embodiments, portion 322B of the foundation 322 may include part of portion 322A of the foundation 322. In some embodiments, portion 322A of the foundation 322 may include part of portion 322B of the foundation 322. In some embodiments, portion 322B of the foundation 322 may be adjacent portion 322A of the foundation 322. In some embodiments, portion 322B of the foundation 322 may be proximal to portion 322A of the foundation 322. In some embodiments, portion 322B of the foundation 322 may be distal from portion 322A of the foundation 322.

[0061] Foundation monitoring system 100A is shown in partial cross-section. A raceway 290 is attached to the foundation 322. The raceway 290 is a conduit into whichthe tube 160 of the foundation monitoring system 100A is disposed. The tube 160 includes a first portion 160A that is substantially vertical, such as within ten degrees, within eight degrees, or within five degrees of vertical. The tube 160 includes a second portion 160B that extends laterally along the foundation 322 away from the first portion 160A. As illustrated, in some embodiments, the second portion 160B is below a ground level 310. In some embodiments, the second portion 160B may be at or above the ground level 310. The sensors 170 within the tube 160 are spaced apart along the foundation 322. As illustrated, in some embodiments, the first portion 160A terminates at the sensor head 110 above the ground level 310. The sensor head 110 is shown attached to the structure 320, nevertheless, in some embodiments, the sensor head 110 may be attached to an exposed part of the foundation 322. In some embodiments, the sensor head 110 may be at or below the ground level 310 while retaining exposure to atmospheric pressure, such as via a vent.

[0062] The foundation monitoring system 100B is similar to the foundation monitoring system 100A, except that the raceway 290 is omitted, and the tube 160 of foundation monitoring system 100B is directly attached to the foundation 322. The tube 160 and the sensors 170 therein of foundation monitoring system 100B are arranged similarly to the tube 160 and the sensors 170 of foundation monitoring system 100A. The sensor head 110 of foundation monitoring system 100B is shown attached to the structure 320, nevertheless, in some embodiments, the sensor head 110 of foundation monitoring system 100B may be attached to an exposed part of the foundation 322.

[0063] Figure 6 illustrates that the vertical positions of sensors in one foundation monitoring system that is attached to a foundation may be different to the vertical positions of sensors in another foundation monitoring system that is attached to the same foundation. Nevertheless, it is contemplated that in some embodiments in which two or more foundation monitoring systems are attached to the same foundation, a vertical position of a sensor of one foundation monitoring system may be the same as a vertical position of a sensor of another foundation monitoring system.

[0064] Figures 7A to 7D schematically illustrate exemplary ways of attaching the foundation monitoring system 100 to the foundation 322. Figures 7A to 7D are cross- sectional depictions transverse to the plane of Figure 6.

[0065] Figures 7A to 7C concern the attachment of a raceway (such as raceway 290 shown in Figure 6) to the foundation 322. In Figure 7A, a spacer 314 is provided between the foundation 322 and another construction, such as flatwork 312. It is contemplated that the spacer 314 may be any convenient material, such as wood or loose brick, that is removable without disturbing the foundation 322 or the flatwork 312. Beneath the spacer 314, and against the foundation 322, is a provision 316 for a raceway. In some embodiments, it is contemplated that the provision 316 for the raceway is an excavated portion of the ground that has been backfilled with soil, sand, and / or gravel. A plurality of raceway anchors 292 are attached to the foundation 322 at discrete locations along the foundation 322. Each raceway anchor 292 may be attached to the foundation 322 by a fastener, such as a screw, or by being keyed into the foundation 322. Each raceway anchor 292 may be configured as a clip, a clamp, a bracket, or the like. The raceway 290 may be attached to each raceway anchor 292 by the clip, the clamp, an adhesive, or a fastener, such as a screw. In some embodiments, the raceway anchors 292 are flexible and / or may be opened to enable removal and replacement of the raceway 290. As illustrated, the raceway anchors 292 are attached to the foundation 322 at the time of constructing the provision 316 for the raceway. In some embodiments, it is contemplated that the raceway anchors 292 may be attached to the foundation at the time when the raceway itself is installed. In the event that a raceway is to be installed against the foundation 322 as a retrofit, the spacer 314 and provision 316 for the raceway are removed. Then a raceway is anchored to the foundation 322 by raceway anchors 292. Then the soil, sand, and / or gravel are returned and packed around the raceway. Then the spacer 314 is replaced.

[0066] Figure 7B shows the raceway anchor 292 attached to the foundation 322 at the time of constructing the provision 316 for the raceway. In some embodiments, it is contemplated that the raceway anchor 292 may be attached to the foundation at the time when the raceway is installed. In the event that a raceway is to be installed against the foundation 322 as a retrofit, the flatwork 312 (or topsoil, if present) abutting the foundation 322 is removed, and then a raceway is anchored to the foundation 322 by a raceway anchor 292. Thereafter, the flatwork 312 is replaced, such as by pouring concrete over the raceway. Alternatively, the topsoil is replaced as desired. It is contemplated that a plurality of raceway anchors 292 are attached to the foundation 322 at discrete locations along the foundation 322.

[0067] Figure 7C depicts the raceway 290 placed within the foundation 322. In some embodiments, it is contemplated that at least a portion of the raceway 290 may be installed within the foundation 322, and at least a portion of the raceway 290 may be attached to an external part of the foundation 322. Sensors 170 installed in such a raceway 290 may be placed within the foundation 322 and along a perimeter of the foundation 322. Additionally, or alternatively, a first raceway 290 may be installed within the foundation, and a second raceway 290 may be attached to an external part of the foundation 322. Sensors 170 of a first foundation monitoring system may be placed within the foundation 322, and sensors 170 of a second foundation monitoring system may be placed along a perimeter of the foundation 322.

[0068] The placement of sensors 170 within a foundation 322, and optionally at the perimeter of a foundation 322, enables the curing of the concrete of the foundation 322 to be monitored. In some embodiments, it is contemplated that the monitoring may be achieved by sensors 170 at spaced intervals, such as at approximately 10 feet (approximately 3 m) intervals, across the foundation 322 — centrally and peripherally. Since the curing of concrete is exothermic, the monitoring may include measuring temperatures at each sensor location continuously or at regular time intervals. A timebased temperature map of the foundation 322 may be created that is akin to a map of the progress of curing over time. When temperature stabilization is observed, the timing of further work, such as the building of a structure on the foundation 322, may be optimized. It is contemplated that the monitoring of curing at specific locations and then monitoring subsequent vertical movement has particular utility in facilitating improving engineering design guidelines.

[0069] Figure 7D depicts an embodiment in which a tube 160 is deployed against a foundation 322 without a raceway, such as illustrated by foundation monitoring system 100B in Figure 6. A plurality of tubing anchors 294 are attached to the foundation 322 at discrete locations along the foundation 322. The tube 160 is clipped to each tubing anchor 294 that is attached to the foundation 322. Each tubing anchor 294 is attached to the foundation 322 by a fastener, such as a screw that penetrates into the foundation 322. In some embodiments, the location of fastening the tubing anchor 294 to the foundation 322 is proximal to the location of a sensor 170 in the tube 160. In an example, the location of fastening the tubing anchor 294 to the foundation 322 serves as a datum reference for data measured by the corresponding sensor 170 in the attached tube 160. Each tubinganchor 294 may be attached to the foundation 322 by a fastener, such as a screw, or by being keyed into the foundation 322. Each tubing anchor 294 may be configured as a clip, a clamp, a bracket, or the like. The tube 160 may be attached to each tubing anchor 294 by the clip, the clamp, an adhesive, or a fastener, such as a screw. In some embodiments, the tubing anchors 294 are flexible and / or may be opened to enable removal and replacement of the tube 160 despite the lack of a raceway 290. In some embodiments, the tube 160 is permanently mounted to the foundation 322.

[0070] A tubing protector 296 is attached to the foundation 322 and covers the tube 160. The tubing protector 296 prevents materials, such as soil, from impacting and distorting or damaging the tube 160. In some embodiments, it is contemplated that thermal insulation 298 may be placed in the tubing protector 296 and around the tube 160. In some embodiments, it is contemplated that the thermal insulation 298 may be omitted. In some embodiments, it is contemplated that the tubing protector 296 may be omitted.

[0071] In embodiments in which the raceway 290 or the tube 160 is attached to the foundation 322 at discrete locations, the raceway anchors 292 or tubing anchors 294 may be positioned such that each sensor 170 is proximal to a corresponding raceway anchor 292 or tubing anchor 294. Each of the above embodiments facilitates positioning of each sensor 170 proximal to a respective portion of the foundation 322 such that movement of a portion of the foundation 322 results in a corresponding movement of the respective sensor 170.

[0072] In some embodiments, the foundation monitoring system 100 is coupled to a foundation 322 of a structure 320 before construction of the structure 320 has been completed. In an example, the tube 160 is coupled to the foundation 322, but a suitable portion of the foundation 322 or the structure 320 is not (yet) available for coupling to the sensor head 110. In such an example, it is contemplated that the sensor head 110 may be coupled to a post, a frame, a temporary wall, or the like, while the structure 320 is being constructed. In some embodiments, the foundation monitoring system 100 is used to monitor the foundation 322 during construction of the structure 320. In some embodiments, the sensor head 110 is transferred to become attached to the foundation 322 or the structure 320 after a suitable portion of the foundation 322 or the structure 320 becomes available for coupling to the sensor head 110. In some embodiments, data fromsensors 152, 154, 170 may be adjusted to compensate for any change of elevation of the sensor head 110 as a result of the transfer to the foundation 322 or the structure 320.

[0073] It is contemplated that in some embodiments, a single foundation monitoring system 100 may be disposed on a foundation. Nevertheless, as shown in Figure 6, multiple foundation monitoring systems 100 may be disposed on a single foundation. In the example illustrated in Figure 6, each foundation monitoring system 100A, 100B is disposed on a corresponding different portion 322A, 322B of the foundation 322. In some embodiments, multiple foundation monitoring systems 100 may be disposed on the same portion of a foundation. In some embodiments, each foundation monitoring system 100 is discrete from the other foundation monitoring systems 100 that are disposed on the same foundation. For example, foundation monitoring system 100A and foundation monitoring system 100B of Figure 6 are not mechanically coupled to each other, except by being coupled individually to different portions 322A, 322B of the same foundation 322.

[0074] In some embodiments, a foundation monitoring system 100 disposed on a foundation does not communicate with another foundation monitoring system 100 disposed on the same foundation. In some embodiments, a foundation monitoring system 100 disposed on a foundation may communicate with another foundation monitoring system 100 disposed on the same foundation. In some embodiments, a foundation monitoring system 100 disposed on a foundation does not communicate with another foundation monitoring system 100 disposed on a different foundation. In some embodiments, a foundation monitoring system 100 disposed on a foundation may communicate with another foundation monitoring system 100 disposed on a different foundation.

[0075] Figures 8A to 8C schematically illustrate exemplary communication links for installations that include multiple foundation monitoring systems attached to a foundation. In some embodiments, each foundation monitoring system of an installation is disposed on the same foundation. In some embodiments, at least one foundation monitoring system of an installation is disposed on a foundation that is different to the foundation on which another foundation monitoring system of the installation is disposed.

[0076] Figure 8A represents an installation 200A of three foundation monitoring systems 210A, 210B, 210C. Each foundation monitoring system 210A, 210B, 210C isconfigured similarly to foundation monitoring system 100, but certain components are omitted from the Figure for clarity. In foundation monitoring system 210A, sensors 212A represent individual sensors (such as sensors 152, 154, and 170), and controller 214A represents the controller 150. In foundation monitoring system 210B, sensors 212B represent individual sensors (such as sensors 152, 154, and 170), and controller 214B represents the controller 150. In foundation monitoring system C, sensors 212C represent individual sensors (such as sensors 152, 154, and 170), and controller 214C represents the controller 150. Each controller 214A, 214B, and 214C communicates with the corresponding sensors 212A, 212B, and 212C, as described above.

[0077] Controller 214A includes, or is coupled to, a transmitter / receiver 216A. Controller 214B includes, or is coupled to, transmitter / receiver 216B. Controller 214C includes, or is coupled to, a transmitter / receiver 216C. Each transmitter / receiver 216A, 216B, 216C facilitates communications with a base station 220. It is contemplated that communications between the base station 220 and each transmitter / receiver 216A, 216B, 216C may be via one or more of a satellite link, a cellular telephone network, or the internet. In some embodiments, the base station 220 includes a control center that monitors a plurality of foundation monitoring systems, such as foundation monitoring systems that are installed on different foundations. In some embodiments, the analysis of data from each foundation monitoring system is performed at the base station 220.

[0078] Each controller 214A, 214B, 214C receives instructions from the base station 220, and transmits data to the base station 220, via the corresponding transmitter / receiver 216A, 216B, 216C. In some embodiments, each foundation monitoring system 210A, 210B, 210C communicates also with each other foundation monitoring system 210A, 210B, 210C via the corresponding transmitter / receiver 216A, 216B, 216C. In some embodiments, each foundation monitoring system 210A, 210B, 210C does not communicate with each other foundation monitoring system 210A, 210B, 210C.

[0079] Figure 8B represents an installation 200B of three foundation monitoring systems 210D, 210E, 21 OF. Each foundation monitoring system 210D, 210E, 21 OF is configured similarly to foundation monitoring system 100, but certain components are omitted from the Figure for clarity. In foundation monitoring system 210D, sensors 212D represent individual sensors (such as sensors 152, 154, and 170), and controller 214D represents the controller 150. In foundation monitoring system 210E, sensors 212Erepresent individual sensors (such as sensors 152, 154, and 170), and controller 214E represents the controller 150. In foundation monitoring system 21 OF, sensors 212F represent individual sensors (such as sensors 152, 154, and 170), and controller 214F represents the controller 150. Each controller 214D, 214E, and 214F communicates with the corresponding sensors 212D, 212E, and 212F, as described above.

[0080] Controller 214D includes, or is coupled to, a transmitter / receiver 216D. The transmitter / receiver 216D facilitates communications with the base station 220. It is contemplated that communications between the base station 220 and the transmitter / receiver 216D may be via one or more of a satellite link, a cellular telephone network, or the internet. The controllers 214E and 214F communicate with the controller 214D. It is contemplated that communications between the controller 214D and controllers 214E and 214F may be via one or more of a satellite link, a cellular telephone network, the internet, a wired connection, Bluetooth, WIFI, or the like. In some embodiments, controller 214D receives instructions from the base station 220, and transmits data to the base station 220, via the transmitter / receiver 216D. In some embodiments, controller 214D acts as a primary controller, and controllers 214E and 214F act as secondary controllers. In an example, controller 214D provides instructions to controllers 214E and 214F, and receives data from controllers 214E and 214F.

[0081] Figure 8C represents an installation 200C of three foundation monitoring systems 210G, 21 OH, 2101. Each foundation monitoring system 210G, 21 OH, 2101 is configured similarly to foundation monitoring system 100, but certain components are omitted from the Figure for clarity. In foundation monitoring system 210G, sensors 212G represent individual sensors (such as sensors 152, 154, and 170), and controller 214G represents the controller 150. In foundation monitoring system 21 OH, sensors 212H represent individual sensors (such as sensors 152, 154, and 170), and controller 214H represents the controller 150. In foundation monitoring system 2101, sensors 2121 represent individual sensors (such as sensors 152, 154, and 170), and controller 2141 represents the controller 150. Each controller 214G, 214H, and 2141 communicates with the corresponding sensors 212G, 212H, and 2121, as described above.

[0082] Installation 200C includes a primary controller 225 that is separate from the controllers 214G, 214H, 2141. The primary controller 225 includes, or is coupled to, a transmitter / receiver 226. The transmitter / receiver 226 facilitates communications with thebase station 220. It is contemplated that communications between the base station 220 and the transmitter / receiver 226 may be via one or more of a satellite link, a cellular telephone network, or the internet. The controllers 214G, 214H, and 2141 communicate with the primary controller 225. It is contemplated that communications between the primary controller 225 and controllers 214G, 214H, and 2141 may be via one or more of a satellite link, a cellular telephone network, the internet, a wired connection, Bluetooth, WIFI, or the like. Primary controller 225 receives instructions from the base station 220, and transmits data to the base station 220, via the transmitter / receiver 226. In some embodiments, primary controller 225 provides instructions to controllers 214G, 214H, and 2141, and receives data from controllers 214G, 214H, and 2141.

[0083] Figures 9A to 9F schematically illustrate an exemplary method of monitoring a foundation. Figures 9A and 9B depict an installation of the foundation monitoring system 100 coupled to a foundation 322 of a structure 320. The foundation monitoring system 100 is coupled to the foundation 322 by any of the methods described above. The foundation 322 is delineated into sections 324. Data from the sensors 170 is used to interpret the elevation of each section 324 of the foundation 322. The combined elevation information of each section 324 provides an elevation profile of the foundation 322. As illustrated, in some embodiments, a datum or reference point (such as the reference point 196, described above) is established at the foundation 322 or the structure 320, such as at a brick ledge. In an example, a transit level is used (such as is known in the art) to establish the datum.

[0084] In some embodiments, at least one sensor 170 is associated with each section 324. In some embodiments, there may not be a sensor 170 associated with a specific section 324. In an example, a first section 324 without an associated sensor 170 may be adjacent to a second section 324 that is associated with a sensor 170. Elevation information concerning the first section 324 may be extrapolated from, interpolated from, or otherwise inferred from, the elevation information concerning the second section 324 obtained via the sensor 170 associated with the second section 324.

[0085] Three sensors (S1 , S2, and S3) are highlighted. Sensor S1 represents the sensor 152 that measures atmospheric pressure and temperature in the sensor head 110. As illustrated, in some embodiments, sensor S2 represents the sensor 154 that is in the sensor head 110 and immersed in the sensor fluid 190. In embodiments in which sensor154 is omitted (or malfunctions), a sensor 170 in the tube 160 is designated as sensor S2. In an example, a sensor 170 in the first (substantially vertical) portion 160A of the tube 160 is designated as sensor S2. In another example, a sensor 170 in the second portion 160B of the tube 160 (such as a sensor 170 located one or more feet or meters laterally distant from the sensor head 110) is designated as sensor S2. In some embodiments, the elevation of sensor S2 relative to a datum (such as reference point 196) is established, such as by direct measurement.

[0086] Sensor S3 represents one of the sensors 170 that are disposed in the second portion 160B of the tube 160 (that extends laterally away from the first portion 160A). In the illustrated example, sensor S3 represents a sensor 170 that is distal from the sensor head 110. In some embodiments, a sensor 170 that is located between the first portion 160A and the second portion 160B of the tube 160 may be designated as sensor S3. In some embodiments, a sensor 170 that is located in the first portion 160A of the tube 160 may be designated as sensor S3. The section 324’ of the foundation 322 in the region of sensor S3 is associated with, or corresponds with, the sensor S3. The location of sensor S3 on (or in) the foundation is known a the time of installation of the foundation monitoring system 100, such as by any of the methods described above. The controller 150 is coupled to each of the sensors S1 , S2, and S3. The level 192 of sensor fluid 190 in the sensor head 110 is between sensor S1 and sensor S2.

[0087] Figure 9A represents the installation at a time ti. Figure 9B represents the installation at a time t2 that is later than time ti , such as days, weeks, months, or years later than time ti. Figure 9B shows that between time ti and time t2, the ground level 310 and the section 324’ of the foundation 322 associated with sensor S3 has sunk, and that sensor S3 has been displaced downwards relative to the sensor head 110 along with the sunken section 324’ of the foundation 322. As illustrated, in some embodiments, the level 192 of the sensor fluid 190 may change from time ti to time t2, such as due to thermal expansion / contraction of the sensor fluid 190. In some embodiments, the level 192 of the sensor fluid 190 does not change from time ti to time t2.

[0088] Figures 9C and 9D present graphs (230, 240, respectively) of pressure versus elevation for the three sensors S1 , S2, and S3. Figure 9C represents the data / information (labeled with subscript “1”) at time ti, and Figure 9D represents the data / information (labeled with subscript “2”) at time t2.

[0089] In the graph 230 of Figure 9C, data point 231 represents the pressure reading taken from sensor S1 at time ti , data point 232 represents the pressure reading taken from sensor S2 at time ti , and data point 233 represents the pressure reading taken from sensor S3 at time ti. In some embodiments, a correction (such as a temperature correction) may be applied to one or more of the pressure readings. In an example, the correction may be based on calibration data. Line 236 represents the atmospheric pressure gradient, and line 238 represents the sensor fluid pressure gradient. The atmospheric pressure gradient 236 is derived from the pressure and temperature readings from sensor S1 . The sensor fluid pressure gradient 238 is derived from one or more of the pressure and temperature readings from sensor S2, sensor S3, or other sensors 170 of the foundation monitoring system 100.

[0090] In the illustrated example, elevation of sensor S3 is derived relative to the elevation of sensor S2. In other examples, the elevation of sensor S3 may be derived relative to the elevation of sensor S1 or relative to the elevation of the sensor fluid level 192. The vertical distance between sensor S1 and sensor S2 in the sensor head 110 is known at the time of manufacturing the sensor head 110, and so the elevation ES11 of sensor S1 relative to the elevation ES2i of sensor S2 is known. The (actual or corrected) pressure reading of sensor S1 at time ti is PS11, the (actual or corrected) pressure reading of sensor S2 at time ti is PS2i, and the (actual or corrected) pressure reading of sensor S3 at time ti is PS3i. The atmospheric pressure gradient 236 is drawn through data point 231 , and the sensor fluid pressure gradient 238 is drawn through data points 232 and 233. The intersection of the atmospheric pressure gradient 236 and the sensor fluid pressure gradient 238 provides the elevation ELLi of the sensor fluid level 192. The sensor fluid level 192 is between sensor S1 and sensor S2, which is an indicator of the validity of the determinations made from the pressure measurements of the sensors 170, including pressure PS3i , of sensor S3. The sensor fluid pressure gradient 238 intersects data point 233 at the derived elevation ES3i of sensor S3. The derived elevation ES3i of sensor S3 provides a quantification of the vertical separation between sensor S2 and sensor S3 (or between the sensor fluid level 192 and sensor S3), and thus provides a quantification of the elevation of the section 324’ of the foundation 322 at sensor S3 relative to sensor S2 (or relative to the sensor fluid level 192).

[0091] The graph 240 of Figure 9D is equivalent to the graph 230 of Figure 9C, but with the data and information corresponding to the situation depicted in Figure 9B. Datapoint 241 represents the pressure reading taken from sensor S1 at time t2, data point 242 represents the pressure reading taken from sensor S2 at time t2, and data point 243 represents the pressure reading taken from sensor S3 at time t2. In some embodiments, a correction (such as a temperature correction) may be applied to one or more of the pressure readings. In an example, the correction may be based on calibration data. Line 236 represents the atmospheric pressure gradient, and line 238 represents the sensor fluid pressure gradient, as in Figure 9C. The atmospheric pressure gradient 236 and the sensor fluid pressure gradient 238 are derived, as described above, using the pressure and temperature readings taken at time t2. Due to differing temperatures, differing pressures, or other factors, the magnitudes of the atmospheric pressure gradient 236 and / or the sensor fluid pressure gradient 238 at time t2 may be different from the magnitudes at time ti.

[0092] As described above, the elevation ESI2 of sensor S1 is known relative to the elevation ES22 of sensor S2. The (actual or corrected) pressure reading of sensor S1 at time t2 is PSI2, the (actual or corrected) pressure reading of sensor S2 at time t2 is PS22, and the (actual or corrected) pressure reading of sensor S3 at time t2 is PS32. The data points 232 and 233 are shown as ghost depictions to illustrate the change in pressure readings of sensors S2 and S3 from time ti to time t2. Also shown is the elevation ES3i of sensor S3 at time ti.

[0093] Because the sensor fluid level 192 has moved downwards (albeit slightly) with respect to sensor S2 (Figure 9B), the hydrostatic head of sensor fluid 190 above sensor S2 at time t2 is lower than the hydrostatic head of sensor fluid 190 above sensor S2 at time ti. Therefore, the pressure PS22 measured by sensor S2 at time t2 is lower than the pressure PS2i measured by sensor S2 at time ti.

[0094] Sensor S3 has moved downwards with respect to sensor S2 by more than the sensor fluid level 192 has moved downwards with respect to sensor S2 (Figure 9B). Because sensor S3 has moved downwards with respect to the sensor fluid level 192, the hydrostatic head of sensor fluid 190 above sensor S3 at time t2 is greater than the hydrostatic head of sensor fluid 190 above sensor S3 at time ti . Therefore, the pressure PS32 measured by sensor S3 at time t2 is greater than the pressure PS3i measured by sensor S3 at time ti.

[0095] The atmospheric pressure gradient 236 is drawn through data point 241 , and the sensor fluid pressure gradient 238 is drawn through data points 242 and 243. The intersection of the atmospheric pressure gradient 236 and the sensor fluid pressure gradient 238 provides the elevation ELL2 of the sensor fluid level 192. As shown, the elevation ELL2 of the sensor fluid, level 192 is lower at time t2 compared to the elevation ELL1 of the sensor fluid, level 192 at time ti. Nevertheless, the sensor fluid level 192 is between sensor S1 and sensor S2, which is an indicator of the validity of the determinations made from the pressure measurements of the sensors 170, including pressure PS32, of sensor S3.

[0096] The elevation ES32 of sensor S3 at time t2 is derived as described above. The elevation ES32 of sensor S3 at time t2 is lower than the elevation ES3i of sensor S3 at time ti , indicating that the elevation of the section 324’ of the foundation 322 at sensor S3 relative to sensor S2 (or relative to the sensor fluid level 192) has fallen between time ti and time t2, as depicted in Figure 9B.

[0097] Figure 9E presents a graph 250 of the difference in (actual or corrected) pressure readings of sensor S3 and sensor S2 over time. Although only a few data points are plotted, the graph 250 may include more or fewer data points. Data point 251 represents the numerical difference between the pressure PS3i measured by sensor S3 at time ti and the pressure PS2i measured by sensor S2 at time ti. Data point 252 represents the numerical difference between the pressure PS32 measured by sensor S3 at time t2 and the pressure PS22 measured by sensor S2 at time t2.

[0098] In some embodiments, the time ti represents a nominal time corresponding to the actual times at which the pressure readings of sensor S2 and sensor S3 are taken. For example, the pressure readings of sensor S2 and sensor S3 may be taken within an hour, within 30 minutes, within 15 minutes, within 5 minutes, within 1 minute, within 30 seconds, within 10 seconds, within 5 seconds, or within 1 second of the time ti. In some embodiments, the time t2 represents a nominal time corresponding to the actual times at which the pressure readings of sensor S2 and sensor S3 are taken. For example, the pressure readings of sensor S2 and sensor S3 may be taken within an hour, within 30 minutes, within 15 minutes, within 5 minutes, within 1 minute, within 30 seconds, within 10 seconds, within 5 seconds, or within 1 second of the time t2.

[0099] The difference between a pressure reading of sensor S3 and a pressure reading of sensor S2 is a function of the hydrostatic head of the sensor fluid 190 in the tube 160 and the sensor head 110, and is related to the vertical distance between sensor S3 and sensor S2 (i.e. the relative elevations of sensor S3 and sensor S2).

[0100] Figure 9F presents a graph 260 of the elevation of sensor S3 relative to sensor S2. Although only a few data points are plotted, the graph 260 may include more or fewer data points. Data point 261 represents the vertical distance between sensor S3 and sensor S2 (equal to the elevation ES3i of sensor S3 minus the elevation ES2i of sensor S2) at time ti. Data point 262 represents the vertical distance between sensor S3 and sensor S2 (equal to the elevation ES32 of sensor S3 minus the elevation ES22 of sensor S2) at time t2.

[0101] The change in the elevation of the sensor S3 relative to the sensor S2 from time ti to time t2 represents the sinking of the section 324’ of the foundation 322 that is associated with sensor S3 relative to the sensor S2.

[0102] In some embodiments, the elevation of sensor S3 is calculated relative to a datum or reference point, such as the reference point 196 (Figures 9A, 9B). In an example, a transit level is used (such as is known in the art) to establish the datum at time ti and / or at time t2. The elevation of sensor S2 relative to the datum is measured, and the methodology described above may be performed to calculate the elevation of sensor S3 relative to the datum.

[0103] In some embodiments, an atmospheric pressure reading of a sensor located external to the sensor head 110 may be used in place of the atmospheric pressure reading taken from sensor S1 at time ti or at time t2. In an example, the atmospheric pressure reading at time ti or at time t2 may be obtained from a local weather station. In some embodiments, the atmospheric pressure reading at time ti or at time t2 may be estimated based on a previous atmospheric pressure measurement and an average of pressure changes measured by one or more of the sensors 154 or 170 since the time of the previous atmospheric pressure measurement.

[0104] Such determinations as described above and shown in Figures 9C to 9F may be made for each sensor 170 in the tube 160. Each sensor 170 is correlated with aspecific section 324 of the foundation 322. Relative movement of individual sections 324 of the foundation 322 over time can be determined as described herein.

[0105] In some embodiments, a rate of change of elevation of a section 324 of the foundation is determined. The rate of change of elevation of a section 324 of the foundation may be based upon the measurements made at time ti , time t?, or at other times. In some embodiments, the rate of change of elevation of a section 324 of the foundation is used to predict a future change of elevation of the section 324 of the foundation. In some embodiments, the predicted future change of elevation of the section 324 of the foundation is compared to threshold value to estimate a time to failure of the section 324 of the foundation. In some embodiments, the estimated a time to failure of the section 324 of the foundation is used to determine whether or when to perform a corrective action to address the potential failure of the section 324 of the foundation.

[0106] Figure 10 is a flowchart of a method 400 of monitoring a foundation, such as foundation 322. Operation 402 includes coupling a tube (such as tube 160) to the foundation. The tube contains a plurality of first sensors (such as sensors 170). In some embodiments, the coupling is performed according to any of the methods described above. Each first sensor is associated with a corresponding section of the foundation (such as corresponding sections 324).

[0107] Operation 404 includes positioning a level of a dielectric liquid (such as dielectric fluid 190) above a second sensor (such as sensor 154) in a sensor head (such as sensor head 110) coupled to the tube.

[0108] Operation 406 includes taking first pressure measurements using each sensor of the plurality of first sensors and the second sensor. In some embodiments, operation 406 includes taking first temperature measurements using each sensor of the plurality of first sensors and the second sensor.

[0109] Operation 408 includes obtaining first atmospheric pressure information corresponding to the first pressure measurements. In some embodiments, operation 408 includes taking one or more atmospheric pressure measurements using an atmospheric pressure sensor. In some embodiments, the atmospheric pressure sensor (such as sensor 152) is located in the sensor head. In some embodiments, operation 408 includes obtaining one or more atmospheric pressure measurements from a sensor external to thesensor head. In some embodiments, the sensor external to the sensor head is located at a weather station. In some embodiments, the first atmospheric pressure information includes an estimate of atmospheric pressure.

[0110] Operation 410 includes determining, from the first pressure measurements and the first atmospheric pressure information, a first elevation of each sensor of the plurality of first sensors relative to the second sensor. In some embodiments, operation 410 includes one or more operations described above, such as with respect to any of Figures 9A to 9F.

[0111] Operation 412 includes taking second pressure measurements using each sensor of the plurality of first sensors and the second sensor. In some embodiments, operation 410 includes taking second temperature measurements using each sensor of the plurality of first sensors and the second sensor.

[0112] Operation 414 includes obtaining second atmospheric pressure information corresponding to the second pressure measurements. In some embodiments, operation 414 includes taking one or more atmospheric pressure measurements using an atmospheric pressure sensor. In some embodiments, the atmospheric pressure sensor (such as sensor 152) is located in the sensor head. In some embodiments, operation 414 includes obtaining one or more atmospheric pressure measurements from a sensor external to the sensor head. In some embodiments, the sensor external to the sensor head is located at a weather station. In some embodiments, the second atmospheric pressure information includes an estimate of atmospheric pressure.

[0113] Operation 416 includes determining, from the second pressure measurements and the second atmospheric pressure information, a second elevation of each sensor of the plurality of first sensors relative to the second sensor. In some embodiments, operation 416 includes one or more aspects or operations described above, such as with respect to any of Figures 9A to 9F.

[0114] Operation 418 includes determining a difference between the first elevation and the second elevation of each sensor of the plurality of first sensors. In an example, for each first sensor, operation 418 includes subtracting the first elevation from the second elevation. In another example, for each first sensor, operation 418 includes subtracting the second elevation from the first elevation. In some embodiments, operation 418includes one or more aspects or operations described above, such as with respect to any of Figures 9E to 9F.

[0115] Operation 420 includes determining a change in elevation of each section of the foundation corresponding to each sensor of the plurality of first sensors. In an example, the change in elevation of a specific section of the foundation is equal to the change in elevation of the corresponding first sensor. In another example, the change in elevation of a specific section of the foundation is substantially equal to the change in elevation of the corresponding first sensor, such as within ten percent, within five percent, within two percent, or within one percent of the change in elevation of the corresponding first sensor.

[0116] In another example, the change in elevation of a specific section of the foundation is extrapolated from, interpolated from, or otherwise inferred from, the change in elevation of one or more first sensors that are proximal to the specific section of the foundation.

[0117] In some embodiments, operation 420 includes one or more aspects or operations described above, such as with respect to any of Figures 9E to 9F.

[0118] In some embodiments, method 400 includes calibrating each sensor of the plurality of first sensors, such as by performing one or more aspects of the methodology described above with respect to Figure 5. In some embodiments, method 400 includes sending any one or more of the first pressure measurements to a base station from a controller, such as controller 150. In some embodiments, the sending includes one or more aspects as described above with respect to Figures 8A to 8C. In some embodiments, method 400 includes sending any one or more of the second pressure measurements to the base station from the controller. In some embodiments, the sending includes one or more aspects as described above with respect to Figures 8A to 8C. In some embodiments, method 400 includes receiving, at the controller, a command from the base station to commence taking the first or second pressure measurements.

[0119] In some embodiments, method 400 provides monitoring of a structure, such as structure 320. In some examples, operation 402 includes coupling at least a portion of the tube (containing the plurality of first sensors) to the structure. In some examples,each first sensor is associated with a corresponding section of the structure and / or a corresponding section of the foundation.

[0120] In some embodiments, method 400 includes one or more aspects or operations described below with respect to method 500.

[0121] Figures 11A and 11 B schematically illustrate an exemplary method of monitoring a foundation that includes the correlating of data between two foundation monitoring systems that are coupled to different portions of a foundation.

[0122] Figure 11A schematically illustrates two foundation monitoring systems 100 coupled to a foundation 322 of a structure 320. The structure 320 may be any structure, such as described above, that sits atop the foundation 322. In the Figure, the foundation monitoring system 100 is represented by each of foundation monitoring system 100C and foundation monitoring system 100D. Foundation monitoring system 100C is coupled to portion 322C of the foundation 322. In some embodiments, the coupling is performed according to any of the methods described above. Foundation monitoring system 100D is coupled to portion 322D of the foundation 322. In some embodiments, the coupling is performed according to any of the methods described above.

[0123] In some embodiments, portion 322D of the foundation 322 may include part of portion 322C of the foundation 322. In some embodiments, portion 322C of the foundation 322 may include part of portion 322D of the foundation 322. In some embodiments, portion 322D of the foundation 322 may be adjacent portion 322C of the foundation 322. In some embodiments, portion 322D of the foundation 322 may be proximal to portion 322C of the foundation 322. In some embodiments, portion 322D of the foundation 322 may be distal from portion 322C of the foundation 322. In some embodiments, portion 322C and portion 322D may be part of, or coupled to, the same foundation 322. In some embodiments, portion 322C may be coupled to a first freestanding foundation and portion 322D may be coupled to a second freestanding foundation that is adjoining the first freestanding foundation. In some embodiments, portion 322C may be coupled to a first freestanding foundation and portion 322D may be coupled to a second freestanding foundation that is coupled to the first freestanding foundation by one or more expansion joints. In some embodiments, portion 322C may be coupled to a first freestanding foundation and portion 322D may be coupled to asecond freestanding foundation that is separated from the first freestanding foundation. In some embodiments, a separation between the first freestanding foundation and the second freestanding foundation may be about 20 feet (about 6.1 m), 100 feet (about 30.5 m), 500 feet (about 152.4 m), 1000 feet (about 305 m), 2000 feet (about 610 m), or greater. In some embodiments, the first freestanding foundation and the second freestanding foundation may be foundations for different portions of the same structure.

[0124] The foundation monitoring systems 100C and 100D are coupled to the foundation 322 by any of the methods described above. The foundation 322 is delineated into sections 324 that are represented as sections 324A in portion 322C of the foundation 322, and sections 324B in portion 322D of the foundation 322. Data from the sensors 170 is used to interpret the elevation of each section 324 of the foundation 322. The combined elevation information of each section 324A provides an elevation profile of the portion 322C of the foundation 322. The combined elevation information of each section 324B provides an elevation profile of the portion 322D of the foundation 322. The combined elevation information of each section 324A and each section 324B provides an elevation profile of the foundation 322 over portions 322C and 322D. As illustrated, in some embodiments, a datum or reference point (such as the reference point 196) is established at the foundation 322 or the structure 320, such as at a brick ledge. In an example, a transit level is used (such as is known in the art) to establish the datum.

[0125] Illustrated components of each of foundation monitoring system 100C and 100D are as described above. Each sensor 170 of foundation monitoring system 100C is associated with a corresponding section 324A of the portion 322C of the foundation 322. Each sensor 170 of foundation monitoring system 100D is associated with a corresponding section 324B of the portion 322D of the foundation 322. Four sensors (SA1 , SF1 , SA2, and SF2) are highlighted. Sensor SA1 represents the sensor 152 in foundation monitoring system 100C that measures atmospheric pressure and temperature in the sensor head 110. Sensor SF1 represents one of the sensors 170 that are disposed in the tube 160 of foundation monitoring system 100C. Sensor SF1 is associated with section 324A’ of the portion 322C of the foundation 322. Sensor SA2 represents the sensor 152 in foundation monitoring system 100D that measures atmospheric pressure and temperature in the sensor head 110. Sensor SF2 represents one of the sensors 170 that are disposed in the tube 160 of foundation monitoring system10OD. Sensor SF2 is associated with section 324B’ of the portion 322D of the foundation 322.

[0126] Figure 11 B presents two graphs 350, 370 schematically illustrating the correlating of data between the sensors SA1 , SF1 , SA2, and SF2. Graph 350 provides exemplary traces of pressure versus time for foundation monitoring system 100C. Line 352 represents atmospheric pressure readings of sensor SA1 , and line 356 represents pressure readings of sensor SF1. In some embodiments, a correction (such as a temperature correction) may be applied to one or more of the pressure readings. In an example, the correction may be based on calibration data.

[0127] In a characteristic portion 366 of the line 352, the (actual or corrected) atmospheric pressure readings of sensor SA1 vary over time according to a distinct pattern. In a stable portion 368 of the line 352, the (actual or corrected) atmospheric pressure readings of sensor SA1 vary over time to a lesser degree than the atmospheric pressure readings in the characteristic portion 366. The stable portion 368 represents a period of relative stability of the (actual or corrected) atmospheric pressure readings of sensor SA1. In an example, the (actual or corrected) atmospheric pressure readings of sensor SA1 vary by up to five percent, up to two percent, or up to one percent of an initial pressure value during the stable portion 368.

[0128] The stable portion 368 is proximal to the characteristic portion 366. In the illustrated example, the stable portion 368 is chronologically after the characteristic portion 366. In another example, the stable portion 368 is chronologically before the characteristic portion 366. In yet another example, the stable portion 368 is within the characteristic portion 366, such as chronologically between a first characteristic section and a second characteristic section.

[0129] In some embodiments, the characteristic portion 366 is chronologically separated from the stable portion 368 by an intermediate period. In some embodiments, the characteristic portion 366 is chronologically adjacent the stable portion 368. In some embodiments, the characteristic portion 366 includes at least part of the stable portion 368. In some embodiments, the characteristic portion 366 includes the entire stable portion 368.

[0130] The characteristic portion 366 and the stable portion 368 occur within a time period 360. The time period 360 encompasses the characteristic portion 366 and the stable portion 368. The time period 360 has a start time 362 and an end time 364. In some embodiments, the time period 360 has a duration of several seconds, such as up to ten seconds, up to twenty seconds, up to thirty seconds, up to forty seconds, up to fifty seconds, or up to sixty seconds. In some embodiments, the time period 360 has a duration of several minutes, such as up to two minutes, up to five minutes, or up to ten minutes. In some embodiments, the time period 360 has a duration longer than ten minutes.

[0131] Data point 354 represents one of the measurements of atmospheric pressure made by sensor SA1 during the stable portion 368. Data point 358 represents the measurement of pressure made by sensor SF1 at substantially the same time as the measurement represented by data point 354, such as within one second, within two seconds, or within five seconds of the time of the measurement represented by data point 354.

[0132] Graph 370 provides exemplary traces of pressure versus time for foundation monitoring system 100D. Line 372 represents atmospheric pressure readings of sensor SA2, and line 376 represents pressure readings of sensor SF2. The time axis of graph 370 is the same as the time axis of graph 350. In some embodiments, a correction (such as a temperature correction) may be applied to one or more of the pressure readings. In an example, the correction may be based on calibration data.

[0133] In a characteristic portion 386 of the line 372, the atmospheric (actual or corrected) pressure readings of sensor SA2 vary over time according to a distinct pattern. In a stable portion 388 of the line 372, the (actual or corrected) atmospheric pressure readings of sensor SA2 vary over time to a lesser degree than the (actual or corrected) atmospheric pressure readings in the characteristic portion 386. The stable portion 388 represents a period of relative stability of the (actual or corrected) atmospheric pressure readings of sensor SA2. In an example, the atmospheric pressure readings of sensor SA2 vary by up to five percent, up to two percent, or up to one percent of an initial pressure value during the stable portion 388.

[0134] The characteristic portion 386 of the line 372 matches the characteristic portion 366 of the line 352 by having the same, or similar, fluctuations of pressure over time as the characteristic portion 366 of the line 352. In an example, the fluctuations of pressure over time of the characteristic portion 386 are within five percent, within two percent, or within one percent of the fluctuations of pressure over time of the characteristic portion 366 of the line 352.

[0135] In some embodiments, the individual pressure values of the characteristic portion 386 of the line 372 are substantially the same as the individual pressure values of the characteristic portion 366 of the line 352. For example, the individual pressure values of the characteristic portion 386 of the line 372 may be within five percent, within two percent, or within one percent of the individual pressure values of the characteristic portion 366 of the line 352.

[0136] In some embodiments, the magnitudes of the individual pressure values of the characteristic portion 386 of the line 372 may not be substantially the same as the magnitudes of the individual pressure values of the characteristic portion 366 of the line 352. In some of such embodiments, the characteristic portion 386 of the line 372 is matched to the characteristic portion 366 of the line 352 according to the magnitudes and pattern of the increases and decreases of the pressure values of the characteristic portion 386 of the line 372 and of the characteristic portion 386 of the line 372. In an example, a match is obtained when the magnitudes of the increases and decreases of the pressure values of the characteristic portion 386 of the line 372 are substantially the same as the magnitudes of the increases and decreases of the pressure values of the characteristic portion 366 of the line 352, such as within five percent, within two percent, or within one percent.

[0137] The characteristic portion 386 and the stable portion 388 occur within a time period 380. The time period 380 encompasses the characteristic portion 386 and the stable portion 388. The time period 380 has a start time 382 and an end time 384. The duration of the time period 380 is the same as the duration of the time period 360.

[0138] The start time 382 and the end time 384 of the time period 380 are established according to the matching of the characteristic portion 366 of the line 352 with the characteristic portion 386 of the line 372. In an example, the characteristic portion 366and the stable portion 368 of the line 352 are positioned over the characteristic portion 386 and the stable portion 288 of the line 372 such that the characteristic portion 366 overlays the characteristic portion 386. The timing of the time period 380 is established relative to the timing of the characteristic portion 386 and the stable portion 388 of the line 372. In an example, the characteristic portion 386 may occur four seconds after the characteristic portion 366, and therefore the start time 382 of the time period 380 occurs four seconds after the start time 362 of the time period 360. Similarly, the end time 384 of the time period 380 occurs four seconds after the end time 364 of the time period 360.

[0139] In the illustrated example, the characteristic portion 386 of the line 372 occurs chronologically later than the characteristic portion 366 of the line 352. In the illustrated example, the start time 382 of time period 380 occurs chronologically later than the start time 362 of time period 360. In the illustrated example, the end time 384 of time period 380 occurs chronologically later than the end time 364 of time period 360.

[0140] In the illustrated example, the time period 380 is offset from the time period 360. In some of such embodiments (such as illustrated), the time period 380 overlaps the time period 360. In other embodiments, the time period 380 does not overlap the time period 360. In some embodiments, the start time 382 of time period 380 occurs chronologically simultaneously with the start time 362 of time period 360. In some embodiments, the start time 382 of time period 380 occurs chronologically before the start time 362 of time period 360. In some embodiments (such as illustrated), the start time 382 of time period 380 occurs chronologically after the start time 362 of time period 360.

[0141] In an example, the offset between the time periods 360 and 380 is due to the corresponding sensor heads 110 of foundation monitoring systems 100C and 100D being located apart from each other. A gust of wind may be experienced by one atmospheric pressure sensor (e.g. SA1 in the illustrated example) chronologically before being experienced by the other atmospheric pressure sensor.

[0142] Data point 374 represents one of the measurements of atmospheric pressure made by sensor SA2 during the stable portion 388. The timing of data point 374 relative to the timing of the start time 382 of time period 380 is equal to the timing of data point 354 relative to the timing of the start time 362 of time period 360. The timing of data point 374 relative to the timing of the end time 384 of time period 380 is equal to the timing ofdata point 354 relative to the timing of the end time 364 of time period 360. Data point 378 represents the measurement of pressure made by sensor SF2 at the same time as the measurement represented by data point 374.

[0143] Although occurring at different times, data point 378 is correlated to data point 358 as having been recorded under similar atmospheric pressure conditions. The derivation of the corresponding sensor elevations using the data points 358 and 378 may be performed as described above with respect to Figures 9C to 9F. The derivation of the elevation of each section 324A (including section 324A’ corresponding to sensor SF1 ) of the portion 322C of the foundation 322 may be performed as described above with respect to Figures 9C to 9F. The derivation of the elevation of each section 324B (including section 324B’ corresponding to sensor SF2) of the portion 322D of the foundation 322 may be performed as described above with respect to Figures 9C to 9F.

[0144] In some embodiments, the elevation of sensor SF1 and the elevation sensor SF2 are calculated relative to a datum or reference point, such as the reference point 196 (Figure 11 A). In an example, a transit level is used (such as is known in the art) to establish the datum. The elevation of sensor SF1 and the elevation sensor SF2 relative to the datum may be determined by the methodologies described herein, such as with respect to Figures 9C to 9F and Figure 11 B.

[0145] Figure 11 C presents an example graph 390 of sensor elevations relative to the reference point 196 over time. Line 392 represents the elevation of sensor SF1 relative to the reference point 196, and line 394 represents the elevation of sensor SF2 relative to the reference point 196. In the illustrated example, line 392 is substantially stable across the given time period. The stability of line 392 indicates that section 324A’ has not undergone much — if any — change in elevation relative to the reference point 196 during the given time period. Line 394 is substantially stable across the given time period prior to time 396. The stability of line 394 indicates that section 324B’ has not undergone much — if any — change in elevation relative to the reference point 196 prior to time 396. However, after time 396, line 394 deviates relatively more than does line 392. The deviations of line 394 after time 396 indicate that section 324B’ has undergone changes in elevation relative to the reference point 196 after time 396 that are different from any changes in elevation experienced by section 324A’. Such a difference in elevationchanges may indicate the development of a problem with the foundation 322, and may be flagged for further investigation.

[0146] In some embodiments, atmospheric pressure readings of a sensor located external to the sensor head 110 of foundation monitoring system 100C may be used in place of the atmospheric pressure readings of sensor SA1. In an example, the atmospheric pressure readings may be obtained from a local weather station. In some embodiments, the atmospheric pressure readings may be estimated based on a previous atmospheric pressure measurement and an average of pressure changes measured by one or more of the sensors 154, 170, SF1 since the time of the previous atmospheric pressure measurement.

[0147] In some embodiments, atmospheric pressure readings of a sensor located external to the sensor head 110 of foundation monitoring system 100D may be used in place of the atmospheric pressure readings of sensor SA2. In an example, the atmospheric pressure readings may be obtained from a local weather station. In some embodiments, the atmospheric pressure readings may be estimated based on a previous atmospheric pressure measurement and an average of pressure changes measured by one or more of the sensors 154, 170, SF2 since the time of the previous atmospheric pressure measurement.

[0148] Figure 12 is a flowchart of a method 500 of monitoring a foundation, such as foundation 322. Operation 502 includes coupling a first plurality of sensors (such as sensors 170, SF1 ) to a first portion of the foundation. In some embodiments, the coupling is performed according to any of the methods described above.

[0149] Operation 504 includes coupling a second plurality of sensors (such as sensors 170, SF2) to a second portion of the foundation. In some embodiments, the coupling is performed according to any of the methods described above.

[0150] Operation 506 includes taking a first set of pressure measurements (such as represented by line 356 in Figure 11 B) using the first plurality of sensors. In some embodiments, operation 506 includes taking a first set of temperature measurements using the first plurality of sensors.

[0151] Operation 508 includes obtaining a plurality of first atmospheric pressure measurements (such as represented by line 352 in Figure 11 B) corresponding to the first set of pressure measurements. In some embodiments, the plurality of first atmospheric pressure measurements are obtained by a first atmospheric pressure sensor (such as sensor 152, SA1 ) coupled to the first plurality of sensors. In some embodiments, the plurality of first atmospheric pressure readings are obtained from a local weather station. In some embodiments, the plurality of first atmospheric pressure readings are estimated based on a previous atmospheric pressure measurement and an average of pressure changes measured by one or more of the first plurality of sensors since the time of the previous atmospheric pressure measurement.

[0152] Operation 510 includes taking a second set of pressure measurements (such as represented by line 376 in Figure 11 B) using the second plurality of sensors. In some embodiments, operation 508 includes taking a second set of temperature measurements using the second plurality of sensors.

[0153] Operation 512 includes obtaining a plurality of second atmospheric pressure measurements (such as represented by line 372 in Figure 11 B) corresponding to the second set of pressure measurements. In some embodiments, the plurality of second atmospheric pressure measurements are obtained by a second atmospheric pressure sensor (such as sensor 152, SA2) coupled to the second plurality of sensors. In some embodiments, the plurality of second atmospheric pressure readings are obtained from a local weather station. In some embodiments, the plurality of second atmospheric pressure readings are estimated based on a previous atmospheric pressure measurement and an average of pressure changes measured by one or more of the second plurality of sensors since the time of the previous atmospheric pressure measurement.

[0154] Operation 514 includes identifying a first time period (such as time period 360 in Figure 11 B) of the plurality of first atmospheric pressure measurements that correlates to a second time period (such as time period 380 in Figure 11 B) of the plurality of second atmospheric pressure measurements. In some embodiments, operation 508 includes one or more aspects of the methodology described above with respect to Figure 11 B.

[0155] Operation 516 includes identifying one or more first data points (such as data point 358 in Figure 11 B) of the first set of pressure measurements taken during the first time period.

[0156] Operation 518 includes identifying one or more second data points (such as data point 378 in Figure 11 B) of the second set of pressure measurements taken during the second time period.

[0157] Operation 520 includes determining, from the one or more first data points, an elevation profile of the first portion of the foundation. In some embodiments, operation 520 includes one or more aspects or operations described above, such as with respect to any of Figures 9C to 9F. In some embodiments, operation 520 includes determining an elevation profile of the first portion of the foundation relative to a datum, such as reference point 196.

[0158] Operation 522 includes determining, from the one or more second data points, an elevation profile of the second portion of the foundation. In some embodiments, operation 522 includes one or more aspects or operations described above, such as with respect to any of Figures 9C to 9F. In some embodiments, operation 522 includes determining an elevation profile of the second portion of the foundation relative to a datum, such as reference point 196. In some embodiments, operation 522 includes determining an elevation profile of one or more sections of the second portion of the foundation relative to an elevation profile of one or more sections of the first portion of the foundation.

[0159] In some embodiments, method 500 includes determining an elevation profile of one or more sections of the first portion of the foundation over time, such as described above with respect to Figure 11 C. In some embodiments, method 500 includes determining an elevation profile of one or more sections of the second portion of the foundation over time, such as described above with respect to Figure 11 C.

[0160] In some embodiments, method 500 includes sending any one or more of the pressure measurements of the first set of pressure measurements to a base station from a transmitter coupled to a first controller, such as controller 150. In some embodiments, the sending includes one or more aspects as described above with respect to Figures 8A to 8C. In some embodiments, method 500 includes sending any one or more of thepressure measurements of the second set of pressure measurements to the base station from a transmitter coupled to a second controller, such as controller 150. In some embodiments, the sending includes one or more aspects as described above with respect to Figures 8A to 8C.

[0161] In some embodiments, method 500 includes receiving, at the first controller, a command from the base station to commence taking the first set of pressure measurements. In some embodiments, method 500 includes receiving, at the second controller, a command from the base station to commence taking the second set of pressure measurements. In some embodiments, method 500 includes one or more aspects or operations described above with respect to method 400.

[0162] In some embodiments, method 500 provides monitoring of a structure, such as structure 320. In some examples, operation 502 includes coupling at least a portion of the first plurality of sensors to the first portion of the structure. In some examples, operation 504 includes coupling at least a portion of the second plurality of sensors to the second portion of the structure.

[0163] Embodiments of the present disclosure have utility in the evaluation of foundation movement before, during, and / or after the building of a structure thereon, and for continuing measurement over time.

[0164] It is contemplated that any one or more elements or features of any one disclosed embodiment may be beneficially incorporated in any one or more other non- mutually exclusive embodiments. While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

What is claimed is:1 . A system for monitoring a foundation, comprising: a tube containing a plurality of first sensors; a sensor head including a first compartment separated from a second compartment, the sensor head coupled to the tube at the first compartment; a second sensor in the first compartment; a controller communicatively coupled to the plurality of first sensors and to the second sensor; and a dielectric liquid in the tube and the first compartment, the dielectric liquid covering each of the first sensors.

2. The system of claim 1 , wherein the sensor head includes a vent into the first compartment.3 The system of claim 2, wherein the vent fluidically couples the first compartment with the second compartment.

4. The system of claim 1 , wherein the second sensor is above a level of the dielectric liquid.

5. The system of claim 4, further comprising a third sensor in the first compartment below the level of the dielectric liquid.

6. The system of claim 1 , further comprising a battery in the second compartment, wherein: the battery is wired to the controller; and the controller is located in the first compartment.

7. The system of claim 1 , wherein the tube is transparent or translucent.

8. A method of monitoring a foundation, comprising: coupling a tube to the foundation, the tube containing a plurality of first sensors, each first sensor associated with a corresponding section of the foundation; positioning a level of a dielectric liquid above a second sensor in a sensor head coupled to the tube; taking first pressure measurements using each sensor of the plurality of first sensors and the second sensor; obtaining first atmospheric pressure information corresponding to the first pressure measurements; determining, from the first pressure measurements and the first atmospheric pressure information, a first elevation of each sensor of the plurality of first sensors relative to the second sensor; taking second pressure measurements using each sensor of the plurality of first sensors and the second sensor; obtaining second atmospheric pressure information corresponding to the second pressure measurements; determining, from the second pressure measurements and the second atmospheric pressure information, a second elevation of each sensor of the plurality of first sensors relative to the second sensor; determining a difference between the first elevation and the second elevation of each sensor of the plurality of first sensors; and determining a change in elevation of each section of the foundation corresponding to each sensor of the plurality of first sensors.

9. The method of claim 8, further comprising: coupling a gas source to a vent in the sensor head; using gas from the gas source to increase a pressure within a first compartment of the sensor head relative to a pressure within a second compartment of the sensor head, the first compartment containing the second sensor; taking third pressure measurements using each sensor of the plurality of first sensors and the second sensor while the pressure within the first compartment is at an increased level; andcalibrating each sensor of the plurality of first sensors according to the third pressure measurements.

10. The method of claim 8, wherein at least one of the first or the second atmospheric pressure information is obtained from a measurement of atmospheric pressure by a third sensor located in the sensor head.

11. The method of claim 8, further comprising sending the first and second pressure measurements to a base station from a controller located in the sensor head, the controller coupled to each sensor of the plurality of first sensors and coupled to the second sensor.

12. The method of claim 11 , wherein sending the first and second pressure measurements includes transmitting the first and second pressure measurements at least in part using one or more of a satellite link, a cellular telephone network, or an internet connection.

13. The method of claim 11 , further comprising receiving, at the controller, a command from the base station to commence taking the first or second pressure measurements.

14. A method of monitoring a foundation, comprising: coupling a first plurality of sensors to a first portion of the foundation; coupling a second plurality of sensors to a second portion of the foundation; taking a first set of pressure measurements using the first plurality of sensors; obtaining a plurality of first atmospheric pressure measurements corresponding to the first set of pressure measurements; taking a second set of pressure measurements using the second plurality of sensors; obtaining a plurality of second atmospheric pressure measurements corresponding to the second set of pressure measurements;identifying a first time period of the first atmospheric pressure measurements that correlates to a second time period of the second atmospheric pressure measurements; identifying one or more first data points of the first set of pressure measurements taken during the first time period; identifying one or more second data points of the second set of pressure measurements taken during the second time period; determining, from the one or more first data points, an elevation profile of the first portion of the foundation; and determining, from the one or more second data points, an elevation profile of the second portion of the foundation.

15. The method of claim 14, wherein identifying the first time period of the first atmospheric pressure measurements that correlates to the second time period of the second atmospheric pressure measurements comprises: identifying a first characteristic pattern of atmospheric pressure versus time of the first atmospheric pressure measurements; and identifying a second characteristic pattern of atmospheric pressure versus time of the second atmospheric pressure measurements that matches the first characteristic pattern.

16. The method of claim 15, wherein: the first time period corresponds to the first characteristic pattern of atmospheric pressure versus time; and the second time period corresponds to the second characteristic pattern of atmospheric pressure versus time.

17. The method of claim 14, wherein the first time period is offset from the second time period.

18. The method of claim 17, wherein the first time period overlaps with the second time period.

19. The method of claim 14, wherein the first atmospheric pressure measurements are obtained by a first atmospheric pressure sensor coupled to the first plurality of sensors.

20. The method of claim 19, wherein the second atmospheric pressure measurements are obtained by a second atmospheric pressure sensor coupled to the second plurality of sensors.

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