34 results about "Hoop strain" patented technology

A method of repairing a section of pipe is described. The method includes applying a first split sleeve and a second split sleeve to the pipe section, functionally associating the first end of the first split sleeve with the first end of the second split sleeve, and applying a compressive force until the internal diameter of the pipe experiences compressive shear hoop strain. The method described produces substantially uniform compressive hoop strain along the length of the pipe section, and may exceed a predetermined value, such as 100 microstrain in compression, for example. The amount of force required may be calculated utilizing maximum operating conditions. The method described may produce an acceptable permanent repair by ensuring that the inner diameter of the section of pipe experiences compressive strain. Also described is a method of reinforcing a section of pipe utilizing these apparatus and methods.

A system and method are provided for determining wall thickness of a structure such as a metallic pressurized pipe. The system includes an optical fiber having a plurality of Fiber Bragg Gratings (FBGs), and a mounting for securing the FBGs over discrete portions of the exterior surface of the pipe such that strain in the pressurized pipe wall is transmitted to the FBGs. The system further includes a light source and a light sensor coupled to an end of the optical fiber. The light sensor converts light reflected back from the FBGs into electrical signals that a digital processor converts into strain measurements. The FBGs are mounted around portions of the pipe expected to have significant metal loss as well as portions of the pipe expected to have negligible metal loss. The method includes at least one of comparing relative strains at locations with negligible metal loss to those with significant metal loss to accurately determine the thickness of the wall with metal loss; compensating for temperature effects by considering relative strains at areas of the pipe with and without metal loss; and measuring axial strain on the pipe with one or more of the FBGs to correct for at least one of bending and torsion effects on hoop strain.

A device for determining soil compaction includes a control member fitted with one or more sensors that measure the response of the control member during co-action between the control member and a soil surface. In one embodiment, this response can be flexure as characterized by a measurable parameter such as strain. A measurement module in communication with the sensor or sensors determines a soil modulus for the soil based on the strain measurement from the sensor or sensors. In one arrangement, the control member includes one set of sensors that measure radial strain and another set of sensors that measures hoop strain. The device can also include a load sensor for measuring the load applied to the control member. In one embodiment the measurement module includes a processor that determines soil modulus based the strain measurements and the measured load.

The present invention discloses a rock long-term strength parameter determination method based on a Casagrande method. The rock long-term strength parameter determination method comprises: drawing a steady-state hoop strain rate-stress level relationship curve according to triaxial creep test results, extending the upper straight section and the lower straight section of the steady-state hoop strain rate-stress level relationship curve to form an angle, making the angular bisector of the angle, making the angular bisector and the steady-state hoop strain rate-stress level relationship curve intersect at a first intersection point, determining the first intersection point as the inflection point of the steady-state hoop strain rate-stress level relationship curve, and obtaining the rock long-term strength parameter based on a Casagrande method so as to achieve the purposes of exact selection of the curve intersection point and substantial reduction of the data error. According to the present invention, the method is simple and effective, and the disadvantages of unclear defined inflection point, high error and the like of the traditional rock long-term strength parameter determination method are effectively improved, wherein the long-term strength parameter determined by the method of the present invention is moderate, can be used for the rock engineering long-term stability analysis, and provides reference for the construction and the long-term operation of the project.

A metering apparatus for determining a characteristic of a fluid, such as the volumetric flow rate, flowing through a non-linear section of a pipe is disclosed having a first strain gauge mountable to the non-linear section of the pipe offset from the bending neutral axis of the non-linear section of the pipe, to detect a bending force on the non-linear section of the pipe induced by the inertia of the fluid flowing through the pipe. A second strain gauge is mountable to the pipe disposed on the bending neutral axis of the non-linear section of the pipe, to detect at least one of the hoop strains, longitudinal strains and radial strains imparted on the pipe by the pressure of the fluid flowing through the pipe. A controller is configured to determine the mass flow rate of fluid flowing through the pipe based on the bending force determined by the first strain gauge and the at least one of the hoop strains, longitudinal strains and radial strains determined by the second strain gauge.

The invention provides a calculation method of a pipe joint hoop strain of a tide load sinking pipe tunnel. The method includes steps of, assuming a back silt layer on the pipe joint as an impervious bed, and regarding the change of the tide level as a large area load pO added on the impervious bed, wherein the location of an underground level is the top face of the impervious bed; not considering about influence of tide on the pipe joint structure, calculating water, soil pressure and subgrade reaction acted on the outer wall of the pipe joint; applying a winkler foundation module, regarding the loop strain calculation as the plane strain problem; analyzing the loop stress and deformation of the pipe joint structure by a load-structure method; through the calculation of cross model stress of the pipe joint, acquiring the relationship of the loop stress strain relationship of the pipe joint; finally, through calculation, acquiring the loop strain distribution of inner and outer walls of the pipe joint under one tide level and influence of the loop strain of every point of inner and outer walls of the pipe joint along with the change of the tide level. The calculation result can be used for predicting the loop strain of the pipe joint of the sinking pipe tunnel in operation stage, judging the part where may generate crack, and carrying out key monitoring and prevention.

The invention discloses a mine filling material compression characteristic experiment device and an experiment method thereof. The experiment device is arranged on a pressure machine, and comprises a cavity for holding a filling material, wherein a bleeding structure is arranged at the bottom end of the cavity; the other end of the cavity is sealed through a slidable piston in the cavity; the bottom end of the cavity is arranged on a lower pressure-bearing plate of the pressure machine; a pressure-bearing column connected with the piston contacts an upper pressure-bearing plate of the pressure machine; an outer wall of the cavity is provided with a plurality of hoop strain foils at different axial positions in a pasting way; the hoop strain foils are connected with a statical strain indicator; a displacement sensor is also arranged between the upper pressure-bearing plate and the lower pressure-bearing plate of the pressure machine; the statical strain indicator and the displacement sensor are in signal connection with a computer connected with a pressure machine measuring system. The mine filling material compression characteristic experiment device provided by the invention can be used for monitoring compression amounts of the filling materials under different stresses and a strain level of an outer wall of a steel cylinder through the pressure machine measuring system, and is simple in structure, convenient to operate, and applicable to compression characteristic tests of dry filling bodies, water sand filling bodies, cemented filling bodies and other filling bodies.

The invention discloses a linear support device for a hoop tension beam for a reactor pressure vessel, which comprises a concrete foundation, a hoop surrounding the upper part of the pressure vessel, and at least two sets of transverse tension beams relatively arranged on the periphery of the pressure vessel. One end of the beam is connected with the hoop, and the other end is connected with the concrete foundation. The invention adopts hoops, cross-tension beams, connecting pins and other structures. The hoops surround the upper outer surface of the pressure vessel. One end of the cross-tension beam is connected to the hoop, and the other end is fixed in the concrete foundation of the reactor pit. It is connected with the hoop through connecting pins, while supporting the reactor pressure device, it can decompose the lateral stress of the pressure vessel during operation, eliminate the flexible swing of the vessel, and enhance the shock resistance of the reactor pressure vessel.

The present invention relates to the field of earth pressure detection, in particular to a cylindrical body circumferential strain earth pressure sensor and a measurement method, the earth pressure sensor includes a cylindrical elastic induction body, a resistance strain gauge, a strain gauge lead wire and a housing, the cylindrical The elastic induction body adopts a cylindrical elastic entity composed of elastic base materials. The cylindrical elastic induction body is added with a structure to increase the compressive modulus. This structure is integrally formed with the cylindrical elastic induction body. The structure includes inner bars and stirrups. The ribs are arranged inside the cylindrical elastic induction body, and the stirrups are installed circumferentially on the upper side or the lower side surface of the cylindrical elastic induction body of the resistance strain gauge. By changing the shape, size and density of the internal ribs, the compressive modulus of the cylindrical elastic sensor is changed to improve the measurement accuracy.

The invention discloses a controllable-pretension FBG (Fiber Bragg Grating) strain hoop gripper system, and belongs to the technical field of a sensor. The controllable-pretension FBG strain hoop gripper system is characterized by being applied to an FBG strain hoop sensor and being used for measuring hoop strain of a pipeline; the controllable-pretension FBG strain hoop gripper system has the key that a long-rod screw is screwed in the end part by penetrating through a screw hole so as to push a wedge to slide forwards, the increment of an FBG wave length is controlled according to the reading of an interrogator, the controllable pretension is realized, the sensor is tightly attached to the outer wall of the pipeline, and optical fibers at the inner part of the sensor can be always in an effective tension measuring state. The pretension-controllable FBG strain hoop gripper system disclosed by the invention has the beneficial effects that problems that the FBG strain hoop sensor cannot be in tight contact with the pipeline, and the hoop strain of the pipeline cannot be accurately measured are solved, the accuracy of the FBG strain hoop sensor is increased, and the pretension-controllable FBG strain hoop gripper system has the advantages that the pretension can be controlled, the manufacturing and the installing are simple and convenient, the mass production is suitable for being carried out, and the like.

The invention relates to a pipeline longitudinal crack detection device and method based on fiber grating sensing. A fiber grating array sensor is arranged on the periphery of an outer wall of a pipeline, and comprises an optical fiber and fiber gratings equally distributed on the optical fiber; the fiber grating array sensor is pre-stretched so as to be clamped and fixed on the outer wall of the pipeline through a magnet, and demodulates a local hoop strain measured by each fiber grating so as to transmit to a data processing unit; the hoop strains of a pipeline with a longitudinal crack are symmetrically distributed by adopting the crack as a center; the local hoop strain at the crack part is the smallest; in a section of area close to the crack, the local hoop strains are increased along the increase of the distance away from the crack; in a section of area far away from the crack, the local hoop strains approach to a constant number; the data processing unit finds out the smallest local hoop strain according to the changing situation of the hoop strains so as to determine a position of the longitudinal crack of the pipeline. According to the pipeline longitudinal crack detection device and the method based on fiber grating sensing provided by the invention, the accurate positioning of the crack is realized, and the fiber grating array sensor is convenient to disassemble and utilize.

The invention relates to a pipeline leakage and corrosion online monitoring device and method based on optical fiber grating sensing. The device comprises a beam splitting system, a demodulating system, a control system and optical fiber grating sensors which are fixed on the outer wall of a long straight pipeline and the outer wall of a bent pipe. The optical fiber grating sensors fixed on the outer wall of the long straight pipeline only have one optical fiber grating and are arranged axially at equal intervals, and judge whether the long straight pipeline leaks or not according to a change condition of detected hoop strain of the pipeline, find out the leak position and acquire uniform corrosion condition; and the optical fiber grating sensors fixed on the outer wall of the long straight pipeline are provided with a plurality of optical fiber gratings and the optical fiber gratings on the same optical fiber grating sensor are uniformly arranged along the circumference, and the optical fiber grating sensors judge non-uniform corrosion condition at the bent pipe according to a change condition of detected local hoop strain. The device is simple in structure, low in cost, convenient to mount and high in monitoring precision.