Inclinometer principle, what is an inclinometer? What s the use?

Installation of the inclinometer tube (see Figure 1). There are two kinds of inclinometer tubes, round and square, the domestic mostly use round, the diameter is 50mm, 70mm, etc., each section is generally 2m long, made of steel, aluminum alloy, plastic, etc., the most commonly used is PVC plastic pipe. Before hoisting the reinforcement cage, the inclinometer pipe is extended to the design length, tied to the reinforcement, and placed in the groove (in the pile hole) along with the reinforcement cage.

The bottom and top of the inclinometer tube should be sealed with a lid to prevent mortar, mud and debris from entering the hole.

Fig.1 Schematic diagram of the installation of the inclinometer tube.

2) The working principle of the inclinometer. According to its working principle, the inclinometer has servo acceleration type, resistance strain gauge type, differential capacitance type, steel string type and so on. There are two more commonly used servo acceleration type and resistance strain gauge type, and the servo acceleration inclinometer has high accuracy and is currently used more.

Fig.2 Schematic diagram of the structure of the inclinometer.

There is a pair of pulleys up and down the inclinometer, the upper and lower wheel pitches are 500mm, and its working principle is to use the gravity pendulum to always maintain the property of the lead straight direction, measure the inclination angle between the axis of the instrument and the vertical line of the pendulum, and the change of inclination angle can be obtained by the conversion of electrical signals, so that the displacement change value of the measured structure can be known.

3) Operational points. If the inclinometer tube is buried, it should be kept vertical, and if it is buried in the pile or underground diaphragm wall, the inclinometer pipe and the reinforcement cage should be tied firmly. The inclinometer tube has two pairs of directional grooves perpendicular to each other, one of which should be perpendicular to the edge of the foundation pit.

When measuring, it is necessary to ensure that the temperature of the inclinometer and the tube is basically the same, and the reading of the indicator is stable before starting to measure. Because the inclinometer measures the relative displacement between the two pulleys (500mm), the immobile point in the inclinometer tube must be selected as the reference point, and the bottom end of the pipe is generally taken as the reference point, and the actual displacement of each point is the accumulation of the relative displacement from the measurement point to the reference point. Inclinometer tube buried below the excavation face:

The rock layer is not less than 1m, and the soil layer is not less than 4m.

This instruction for use is only applicable to the VWD-J vibrating wire seam gauge produced by our company, including VWD-20J, VWD-50J VWD-100J and other models.

VWD-J vibrating wire joint gauge is suitable for long-term placement in concrete structures or other material structures and surfaces, measuring the opening and closing degree (displacement) of expansion joints or peripheral joints of structures, and can simultaneously measure the temperature of buried points.

The sensor of the vibrating wire gauge adopts the VWD vibrating wire displacement gauge, which is composed of its supporting accessories, and the vibrating wire gauge has the function of parameter recognition.

Are you surveying? I'm a military tester.

Inclinometers are divided into portable inclinometers and fixed inclinometers, portable inclinometers are divided into portable vertical inclinometers and portable horizontal inclinometers, fixed types are divided into uniaxial and biaxial inclinometers, and the most widely used is portable inclinometers.

Inclinometer Overview: Portable digital inclinometers are often used to monitor the lateral displacement of landslide areas and deep hole excavated soils, and are also used to monitor deformations such as embankment structures. At its core is a two-force balanced servo accelerometer. It has the advantages of durability, high precision, and quick response.

Principle: Inclinometer tubes are usually installed in vertical boreholes that pass through unstable soil to the lower stable formation. The deformation of the inclinometer tube is observed using a digital vertical activity inclinometer probe, control cables, pulley units, and a reader.

The first observation can establish an initial cross-section of the displacement of the inclinometer. Subsequent observations show changes in the displacement of the section as the ground moves. During the observation, the probe moves from the bottom of the inclinometer tube to the top, pauses at a half-meter spacing and performs the measurement tilt.

The inclination of the probe is measured by two force-balanced servo accelerometers. An accelerometer measures the longitudinal position of the groove of the inclinometer tube, i.e., the inclination of the plane on which the gauge wheel is located on the inclinometer probe. The other accelerometer measures the inclination perpendicular to the plane of the wheel.

The inclination can be converted to lateral displacement. Comparing the current and initial observations, the amount of change in lateral shift can be determined, showing the movement displacement of the formation. Plotting the amount of change in the offset yields a high-resolution cross-section of the displacement.

This cross-sectional view helps to determine the magnitude, depth, direction, and rate of ground motion displacement.

Inclinometer is an instrument used to measure the top angle and azimuth angle of engineering structures such as boreholes, foundation pits, foundation foundations, walls and dam slopes. The mold inclinometer is an in-situ monitoring instrument for determining the inclination angle and azimuth angle of boreholes. In the fifties of the last century, inclinometers were used to monitor geotechnical projects such as earth-rock dams, roadbeds, slopes and tunnels.

Since the 80s, China has introduced inclinometers produced by the United States, Japan, Britain and other countries to carry out in-situ monitoring of some major geotechnical projects, and has achieved good results. Subsequently, some related research institutes developed intelligent inclinometers such as resistance strain gauges, accelerometers and electronic meters. So far, all kinds of inclinometers are widely used in the fields of water conservancy and hydropower, mineral metallurgy, transportation and urban construction geotechnical engineering, and have played an important role in ensuring the design, construction and safety of geotechnical engineering tunnels.

The measured value of the fixed inclinometer is the change of the real-time measured value relative to the benchmark value, so the accuracy of the reference value selection will directly affect the accuracy of the measured value.

In the external load change does not take the same time, stable temperature of the same time 3 times similar reading, after the average as the benchmark value, the fixed inclinometer installed in the book of friends and disadvantages of the concrete should be selected after the measurement value of the heat of hydration. After the benchmark value is selected, it should be recorded as the benchmark value for calculation.

In order to make the benchmark value of the god more accurate, the above operation can be repeated twice, if the two measurements are basically the same (error), then the reference value is correct.

In the event of a deviation in the measurement value of a fixed state inclinometer, the reference value can be recalibrated using the above method.

After decades of theoretical research and application practice, the inclinometer is becoming more and more lightweight, simple and automated, and the resulting effect is becoming more and more obvious. In order to ensure the safety of geotechnical engineering design, construction and operation, a variety of inclinometers play an important role. It is believed that with the construction of geotechnical engineering informatization, various monitoring methods will be widely emphasized.

For a site or structure, the observation and operation points should be arranged reasonably according to local conditions. Generally, the horizontal distance of adjacent observation points is required to be a hole depth, and the observation points can also be appropriately encrypted or reduced according to the geotechnical engineering grade. During construction, it is required that the drilling hole is a plumb weight, and the deviation angle should be less than 2°.

The diameter of the final hole should be 30mm larger than the outer diameter of the inclinometer tube, and the drilling depth should exceed the deepest displacement zone by 5m. All boreholes should be accepted before the excavation pipe is buried, and can only be buried after passing the test.

Inclinometer is an instrument used to measure the top angle and azimuth angle of engineering structures such as boreholes, foundation pits, foundation foundations, walls and dam slopes1.

When the vertically suspended tilt switch probe is subjected to external force and deviates from the vertical position by more than 17 degrees, the metal ball contact inside the tilt switch acts, and the normally closed contact is disconnected. When the external force is withdrawn, the tilt switch returns to a vertical state, and the metal ball contacts are closed again.

Inclinometers are now widely used in dams and geotechnical engineering to measure the inclination of foundations or structures, and such sensors must have good impact resistance, otherwise they cannot be used in engineering. At present, whether it is a servo accelerometer or a resistance strain gauge inclinometer, there is a fatal weakness that is poor impact resistance, which makes the inclinometer very easy to damage and has a high repair rate. The inclinometer is a movable reusable instrument, and its impact-resistant type should be particularly important.

The steel cable with the center diameter is extruded from sliding in the cable, and the tinned copper core of the multi-core section can fully meet the requirements of the above performance. Polyurethane is the most stable material in the cable material, it is extremely difficult to change the chemical and physical properties after extrusion and shaping, so it is not afraid of fire, acid resistance, alkali resistance, damage resistance, low temperature is not hard, high stability is not soft, sharp rock is difficult to damage it, it should be the most ideal supporting cable for the inclinometer. <>

When the fixed inclinometer leaves the factory from the manufacturer, it is packaged in parts, and the first thing to check is whether the guide wheel of the inclinometer rotates flexibly and whether the torsion spring is strong. Check whether the sensor parts are working normally (based on the plumb line, the reading on one side of the high-end guide wheel tends to increase, and the reading on the other side decreases), intercept the connecting wire rope according to the design elevation (the design elevation is increased by 25cm), and connect the fixed inclinometer with the wire rope end to end, and assemble the measurement unit according to the number required by the design drawing. Hoisting is to put into the inclinometer tube in the order of each measuring unit, and each measuring unit is connected with a wire rope, the connection must be firm, and the direction of all guide wheels of each measuring unit must be consistent.

If only one set of fixed inclinometer is installed in the measuring hole, only the head of the fixed inclinometer needs to be connected with the wire rope. During installation, according to the displacement direction that needs to be observed by the measured body, the positive direction (high wheel direction) of the rod guide wheel should be aligned with the main direction of the measuring plane of the inclinometer tube, slowly slide into the measuring tube, straighten out the instrument cable, and tie the cable with the hoisting wire rope with a self-locking cable tie at each depth, and do not tie it to the rod component of the fixed inclinometer. When placed at the design elevation, the final hoisting wire rope is fixed on the transverse axis of the orifice device, locked with a lock, and the cable is buried according to the design direction.

It should be noted that each set of fixed inclinometers should be numbered and recorded in order, and all cables should be relaxed and not tightened. After the decentralization is completed, the elevation of the instrument should be checked to see if it is accurate, and the hoisting wire rope should be pulled to check whether each sensor is working properly with a reader, and then a stable initial reading should be recorded. If you find a problem, you can pull out the fixed inclinometer and reinstall it.

Finally, the orifice should be provided with protection facilities, and the observation cable should be fixed and buried according to the design direction.