4.1 An inclinometer is a deformation monitoring system, which uses a grooved pipe or casing with internal longitudinal grooves aligned with the anticipated direction of movement, installed in either a soil/rock mass or a geotechnical structural element. The inclinometer casing can be surveyed with a single traversing probe or with an array of in-place inclinometer (IPI) gauges connected to a data logger. The measurement and calculation of deformation normal to the axis of the inclinometer casing is done by passing a probe along the length of this pipe or placement of a sensor array, guided by the internal grooves. The probe or sensor array measures the inclination of the pipe, usually in two orthogonal directions 90° apart (X- and Y-direction) with respect to the axis of the casing (Z-direction, usually the line of gravity). Measurements are converted to distances using trigonometric functions. Successive surveys compared with an initial survey give differences in position and indicate deformation normal to the axis of the inclinometer casing. In most cases the inclinometer casing is installed in a near-vertical hole, and the measurements indicate subsurface horizontal deformation. In some cases, the inclinometer casing is installed horizontally, and the measurements indicate vertical deformation.

4.2 Inclinometers are also called slope inclinometers or slope indicators. Typical applications include measuring the rate and direction of landslide movement and locating the zone of shearing, monitoring the magnitude and rate of horizontal movements for embankments and excavations, monitoring the settlement and lateral spread beneath tanks and embankments, and monitoring the deflection of bulkheads, piles or structural walls.

Note 1: The precision of this standard is dependent on the competence of the personnel performing it and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing. Users of this standard are cautioned that compliance with Practice D3740 does not in itself ensure reliable results. Reliable testing depends on many factors; Practice D3740 provides a means of evaluating some of those factors.

1.1 This standard covers the use of inclinometers to monitor the internal movement of ground, or lateral movement of subsurface structures. The standard covers types of instruments, installation procedures, operating procedures, and maintenance requirements. The standard also provides formulae for data reduction.

1.2 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026 unless superseded by this standard.

1.2.1 The procedures used to specify how data are collected, recorded or calculated in this standard are regarded as the industry standard. In addition, they are representative of the significant digits that generally should be retained. The procedures used do not consider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the user’s objectives; it is common practice to increase or reduce significant digits of reported data to be commensurate with these considerations. It is beyond the scope of this standard to consider significant digits used in analytical methods for engineering design.

1.3 Units—The values stated in SI units are to be regarded as the standard. The inch-pound units given in parentheses are for information only. Reporting of test results in units other than SI shall not be regarded as nonconformance with this standard.

1.4 This standard offers an organized collection of information or a series of options and does not recommend a specific course of action. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this standard may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project’s many unique aspects. The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus process.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.