AASHTO R 45:13(2017) Standard Practice for Installing, Monitoring, and Processing Data of the Traveling Type Slope Inclinometer.
2.2. Guide casing:
2.2.1. Guide casing, usually round extruded plastic, with four equally spaced longitudinal grooves on the inside of the casing compatible with the particular torpedo sensor used. However, some casing may not be grooved because the torpedo sensor maintains proper orientation by use of locking metal orientation rods. Some inclinometers may be used in square steel casing with the torpedo sensor guide wheels tracking in opposite corners of’ the casing. The casing comes in assorted diameters and may come in any convenient length, such as 1.52- or 3.05-rn (5- or 10-fl) sections.
2.3.1. The couplings may be extruded plastic with four equally spaced grooves and usually come in
152-mm (6-in.) lengths. In cases where settlement is expected. longer couplings may be used to join the sections of casing. The resulting gap between casing sections allows the casing to telescope together as compression of the surrounding materials occurs. Alternately, a coupling mechanism may be included as part of the guide casing.
2.4. Installation Tools:
2.4.1. Inclinometer guide casing installation tools specified by the manufacturer, normally consisting of hacksaw, casing clamp, casing anchor (recommended), tape measure, and a device for marking casing grooves such as a felt tip marker or tile. A special wheel groove alignment tool, duct or masking tape, and solvent cement may be needed for plastic casing. A vibrator and/or grout pump may be used for backfill compaction and placement if necessary.
2.5.1. Plugs compatible with the particular guide casing arc used for protecting the top and bottom of the casing from mud and debris. A conical plug may be used to ease insertion of the casing into a rough-sided hole.
2.6. Protective Device (Optionab:
2.6.1. Hole cover or other protective device to minimize vandalism and large enough [152 mm (6 in.)] to allow the cable clamp-guide wheel assembly to be installed on top of the casing. A metal pipe with either a threaded cap or hinged lid with hasp and lock may be used. For protection from impacts by construction traffic, bollards or barriers may be installed.
3. DRILLING AND HOLE PREPARATION
3.1. The size of the drill hole should be large enough to accommodate the particular size casing used and depends on the particular installation, locale, materials encountered, depth of the hole, available backfill materials, or the discretion of the engineer. Larger holes facilitate backfilling. Minimum diameter may be only sufficient to accommodate the casing used. This is applicable in cases where the material may close quickly. Normally, the drill hole may be approximately two times the outside diameter of the casing or a minimum of 127 to 152 mm (5 to 6 in.). The hole should be as vertical as possible (vertical inclination should be less than 3 degrees), and drilled several meters (at least 3 m, or as directed by the engineer) into stable material below or beyond the anticipated zone of movement. Usually, the borehole should extend into rock or soil to achieve sufficient rigidity to provide the fixity of the inclinometer. The bottom 3 m (Or as directed by the engineer) of the inclinometer casing should be embedded below the lowest possible failure plane and should extend into hard or very dense material to assure that the future readings do not show any movement at the bottom of the inclinometer casing.AASHTO R 45 pdf download.