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IS 14395:1996 is the Indian Standard (BIS) for guidelines for monitoring of rock movements using probe inclinometer. This standard provides guidelines for monitoring the magnitude, rate, and direction of lateral rock movements using a probe inclinometer. It covers the principle of operation, equipment requirements, installation procedures for the inclinometer casing, and methods for data acquisition, processing, and interpretation. The goal is to assess the stability of rock slopes, foundations, and excavations.
Guidelines for monitoring of rock movements using probe inclinometer
Standard Guide for Manual Monitoring of In-Place Inclinometers
Provides guidance on installation, data collection, and data reduction for manual probe inclinometers.
BS EN ISO 18674-3:2017BSI Group (British Standards Institution), UK / ISO, International
HighCurrent
Geotechnical investigation and testing — Geotechnical monitoring by field instrumentation — Part 3: Measurement of displacements across a line: Inclinometers
Specifies principles and procedures for inclinometer measurements as part of a comprehensive geotechnical monitoring framework.
ISRM (1977)International Society for Rock Mechanics (ISRM), International
MediumCurrent
Suggested Method for Monitoring Rock Movements Using Inclinometers
A foundational guideline document specifically for using inclinometers in rock, similar in focus to the IS code.
Key Differences
≠The IS code is specifically a guideline for 'rock movements', whereas ASTM D6211 and ISO 18674-3 cover monitoring in both soil and rock, making them more broadly applicable.
≠Modern standards like ISO 18674-3 and ASTM D6211 provide more detailed procedures for systematic error correction, such as bias shift (rotation) correction, while IS 14395 primarily uses the 180-degree check for data validation.
≠ISO 18674-3 specifies performance requirements for the equipment and ties reporting requirements into a larger framework (Eurocode 7), making it more prescriptive than the IS 'guideline'.
≠The international standards place a stronger emphasis on designing the grout mix to match the stiffness of the surrounding ground, whereas IS 14395 provides a more recipe-based approach (e.g., 2-5% bentonite).
Key Similarities
≈All standards are based on the identical operating principle of a biaxial sensor probe being lowered into a grooved casing to measure inclination at discrete intervals.
≈The fundamental installation procedure is consistent across all standards, including drilling a borehole, installing the casing, grouting the annulus, and aligning grooves with the anticipated direction of movement.
≈All standards mandate taking a set of initial (baseline) readings after the installation has stabilized, which serves as the datum for all future measurements.
≈The use of a 180-degree check (taking readings in the same grooves with the probe rotated) is a common procedure in all documents to verify instrument function and account for bias.
≈The basic method for calculating lateral deviation from inclination data (Deviation = L × sin(θ)) and summing it cumulatively from a stable base is uniform across all standards.
Parameter Comparison
Parameter
IS Value
International
Source
Primary Scope
Guidelines for monitoring of rock movements.
Monitoring of in-place inclinometers (in soil and rock).
ASTM D6211
Standard Probe Gauge Length
Usually 0.5 m (Clause 5.3.1).
Commonly 0.5 m or 2 ft.
ASTM D6211
Reading Interval
Should be equal to the probe gauge length (Clause 7.1).
Shall be equal to the gauge length of the probe (Section 8.3).
ASTM D6211
Groove Alignment
One set of grooves oriented in the principal direction of anticipated movement (Clause 6.3.3).
One set of grooves aligned with the principal direction of movement (Section 7.5.3).
ASTM D6211
Grout Mix Guideline
Cement-bentonite mix (2-5% bentonite by weight of cement) should be weaker than surrounding rock (Clause 6.4.1).
Grout stiffness should be designed to match the surrounding ground stiffness (Annex C).
BS EN ISO 18674-3:2017
Application of 180° Check
Used as a check for data quality; the difference between A0 and A180 readings should be constant (Clause 7.2).
Used to calculate a bias correction value (B = (A0+A180)/2) which is then applied to the data (Section 9.2.2).
ASTM D6211
System Precision
Not explicitly defined; general guidance is given.
Typical manual system precision is stated as approx. ±2 to 4 mm per 25 m of depth (cumulative).
ASTM D6211
⚠ Verify details from original standards before use
Key Values6
Quick Reference Values
Typical casing outside diameter70 mm to 85 mm
Standard probe reading interval (gauge length)0.5 m
Maximum recommended casing deviation from vertical3 degrees (Clause 6.2.1)
Recommended grout mix (cement:bentonite:water)1:0.3:1 by weight (Annex A)
Initial observation frequencyTwice a day for the first two days (Clause 7.2)
Checksum tolerance for A and B readingsShould be constant, variations indicate errors (Clause 8.2)
Key Formulas
Δx = L * sin(θ) — Incremental lateral deviation at a depth
X = Σ(Δx) — Cumulative lateral displacement from the bottom of the casing
Checksum = Reading(A) + Reading(B) — Used to verify reading quality
Tables & Referenced Sections
Key Tables
No tables data
Key Clauses
Clause 4 - Principle
Clause 6 - Installation of Inclinometer Casing
Clause 7 - Taking Observations
Clause 8 - Processing and Presentation of Data
Clause 9 - Interpretation of Results
Frequently Asked Questions4
What is the primary purpose of a probe inclinometer?+
To measure the lateral displacement profile along a borehole, typically to monitor the stability of slopes, excavations, or dam abutments.
Why is the casing grouted in the borehole?+
To ensure the casing moves with the surrounding rock mass, accurately transferring the ground deformation to the inclinometer probe (Clause 6.3).
How often should initial readings be taken?+
A set of initial readings should be taken immediately after installation and then twice a day for the first two days to establish a reliable baseline (Clause 7.2).
In which direction should the casing grooves be aligned?+
One pair of grooves (A-A axis) should be aligned in the direction of the anticipated principal movement (Clause 6.2.2).