Method and Device for Measuring Pressure Exerted by Earth Material

Patent metadata

Field	Value
Publication number	US-2016123136-A1
Application number	US-201414896007-A
Country	US
Kind code	A1
Filing date	Jun 4, 2014
Priority date	Jun 5, 2013
Publication date	May 5, 2016
Grant date	—

Abstract

A method for measuring pressure exerted by earth material includes: providing a pipe with a longitudinal bore defining an inner diameter, providing a device with sensors to sense said inner diameter, wherein the device is to be moved within the pipe along the longitudinal bore, while a measurement of the inner diameter is taken in a first transversal direction at one longitudinal position of the pipe. Then a measurement of the inner diameter in a second transversal direction at the predetermined longitudinal position is taken, wherein the second transversal direction is oriented differently to the first transversal direction. Finally, an ovalization of the pipe is derived at that predetermined longitudinal position of the pipe through subtracting a diameter value of the first transversal direction from a diameter value of the second transversal direction.

First claim

1 . A method for measuring pressure exerted by earth material, comprising:
providing a pipe in the earth material, wherein the pipe has a longitudinal bore defining an inner diameter of the pipe, providing a device adapted to be moved within the pipe along the longitudinal bore, wherein the device comprises sensors adapted to sense the inner diameter of the pipe, moving the device along the pipe, taking a measurement of the inner diameter of the pipe in a first transversal direction at at least one predetermined longitudinal position of the pipe, taking a measurement of the inner diameter of the pipe in a second transversal direction at the at least one predetermined longitudinal position of the pipe, wherein the second transversal direction is oriented differently to the first transversal direction, deriving an ovalization value of the pipe at the at least one predetermined longitudinal position of the pipe through subtracting the inner diameter measurement of the first transversal direction from the inner diameter measurement of the second transversal direction.

2 . The method according to claim 1 , wherein the first transversal direction is oriented perpendicular to the second transversal direction.

3 . The method according to claim 1 , wherein there are two or more further transversal directions oriented each in an angle to each other transversal direction.

4 . The method according to claim 1 , wherein the pipe is one hollow cylinder or a sequence of sections of hollow cylinders.

5 . The method according to claim 1 , wherein the pipe is an inclinometer pipe, especially comprising two or more pairs of inside guiding channels for guiding the device.

6 . The method according to claim 1 , wherein the measurements of the inner diameter value at the different transversal directions are fitted to a theoretical oval of the pipe providing the best fit at a specific longitudinal position.

7 . The method according to claim 6 , wherein the ovalization value is corrected for an inclination of the pipe, wherein the device further comprises at least one inclination sensor to determine a specific inclination of the device and the pipe at any longitudinal position of the device.

8 . The method according to claim 6 , wherein the correcting of the ovalization value for inclination of the pipe is calibrated based on the inclination at a specific section of the pipe.

9 . The method according to claim 1 , wherein a value representing the change in lateral pressure CP, being defined as a major principle lateral stress increment in a surrounding ground, is derived from a change in ovalization value applying an analytical solution based on elasticity theory based on the formula:
CP=YG*(1+alpha)/(8*(1−SR)*cos(2*DS))*COV with
alpha=3YP*IP*(5−PG)/(RP A 3*YG)
wherein YP is Young's modulus of the pipe and YG is Young's modulus of surrounding ground, SR is the stress ratio in between the principle stress increments in a plane at infinity, COV is the change in ovalization value, PG is Poisson's ratio of the surrounding ground, RP is a mean radius of the pipe, IP is a circumferential cross-section moment of inertia of the pipe, DS is an angle between a direction of the major principle stress increment and a direction of a minor axis of an equivalent oval, wherein the stress ratio SR of the principle stress increments is defined by dividing a minor principle stress increment by the major principle stress increment, wherein, through assumption of constrained boundary conditions at infinity in direction of the minor principle stress increment, the stress ratio SR of principle stress increments is considered equal to the Poisson's ratio of the surrounding ground PG.

10 . The method according to claim 9 , wherein the angle DS obtained through measurement of a horizontal displacement of the surrounding ground HD based on an assumption
that the major principle stress increment occurs in direction of the horizontal displacement of the surrounding ground HD.

11 . A probe device for measuring pressure exerted by earth material around a pipe, comprising: a longitudinal frame comprising an attachment for a cable intended to displace the probe device within the pipe along a longitudinal bore of the pipe,
at least one sensor adapted to sense an inner diameter of the pipe, at least one sensor adapted to determine a longitudinal position of the probe device in the pipe, and a control unit connected with the sensors, wherein the probe device is adapted to take a measurement of the inner diameter of the pipe in a first transversal direction at at least one predetermined longitudinal position of the pipe and to take a measurement of the inner diameter of the pipe in a second transversal direction at the at least one predetermined longitudinal position of the pipe, wherein the second transversal direction is oriented differently to the first transversal direction, and wherein the control unit is adapted to derive an ovalization value of the pipe at the at least one predetermined longitudinal position of the pipe through subtracting a diameter value of the first transversal direction from a diameter value of the second transversal direction.

12 . The probe device according to claim 11 , wherein three wheels are provided along a longitudinal axis of the probe device and wherein an upper and a lower wheel are attached rotatably at the longitudinal frame of the probe device and which is connected to the cable and wherein a middle wheel is attached on a movable axis being parallel to an axis of the other two wheels.

13 . The probe device according to claim 11 , wherein the at least one sensor sensing the inner diameter of the pipe is a tilt sensor and/or wherein the at least one sensor determining the longitudinal position of the probe device is a rotation sensor provided at a cable pulling wheel.

Assignees

• Eth Zuerich

Inventors

• Puzrin Alexander
• Schwager Markus
• Schmid Andreas
• Bleiker Ernst

Classifications

• G01B7/16

  for measuring the deformation in a solid, e.g. by resistance strain gauge · CPC title

• E21B47/08 Primary

  Measuring diameters or related dimensions at the borehole · CPC title

• G01B7/13

  Internal diameters · CPC title

• E21B47/04

  Measuring depth or liquid level · CPC title

• E21B47/017

  Protecting measuring instruments · CPC title