SAAV can be installed in 27 mm ID conduit similar to previous model ShapeArrays. When installing SAAV in this manner, the borehole should be pre-cased with the 27 mm conduit. This installation method is susceptible to buoyancy effects and care must be taken to avoid sinuating the PVC prior to installing the ShapeArray.
The following table outlines the tools and equipment required to install an SAAV into 27 mm ID conduit.
|Pry bar||1” PVC End cap *||Reel stand and pole||Phillips Screwdriver|
|Hammer||Pipe cutter||Box cutter||Markers|
|Pliers||SAA TopStack Assembly with 2 screws *||Wire cutters||PEX cutter *|
PVC cement and primer
|Schedule 40 PVC coupling 1” *||Microsoft Windows Laptop computer with latest Measurand software||Small flat-headed screwdriver|
|Deburring tools for PVC||1” Pipe Clamp (hanging fixture) *||Measurand Interface (e.g. SAA Field Power Unit)|
|Duct tape||3/4" chain (1.5 m of chain per m of conduit)||SAA X-Mark Protractor *|
* Starred items are included in the 27 mm ID conduit installation kit
NOTE - Measurand ShapeArrays are shipped on wooden reels with wooden facets stapled to the outside. A pry bar, hammer, and pliers will be required to remove the facets from the reel prior to following the steps below.
The following short video provides a great overview of the installation process. Each step in the installation process is described in more detail following the video.
Step 1 - Choose the Right Conduit
Figure 1: 27 mm ID electrical conduit, end cap, and coupler appropriate for ShapeArray installation
Step 2 - Choose the Right Adhesive
PVC couplings are attached with PVC solvent cement. In cold temperatures, it is imperative to use an appropriately rated cement. Do not use too much cement, as it can squeeze into the inner part of the conduit. Debur, clean, and use a solvent cleaner on the conduit before applying cement. Most manufacturers specify applying glue to only one surface of the joint.
Figure 2: An example of PVC solvent cement
Step 3 - Prepare the Conduit
All PVC conduit ends should be kept clean from dust, oil, and snow. Look inside the PVC pipes to ensure that no foreign objects are inside the PVC pipe. The edges of conduit over which the ShapeArray is being installed should be smoothed using a deburring tool to prevent abrasion.
Figure 3: Preparing conduit - (a) examples of deburring tools, (b) cleaning and deburring the conduit
Step 4 - Assemble the Conduit
It is easier to assemble the PVC conduit as it is lowered into the borehole. Using PVC cement and duct tape, secure the end cap onto the bottom-most piece of PVC before inserting it into the borehole. Lower the first piece of PVC conduit then glue the next piece on and tape the joint. Due to buoyancy effects, an assistant will be needed to hold the pieces in place while working. Keep adding more conduit, gluing and taping each joint, until the required length of conduit has been assembled. Glue the bottom part of the top stack included in the SAA Install Kit to the top of the PVC conduit at this time.
Figure 4: Assembling the conduit as it is lowered into the borehole - (a) Assistant holding it in place, (b) next piece glued and taped at the joint
Step 5 - Avoid Buoyancy During Grouting
A factor which must be considered during installation is the buoyancy of the PVC conduit. Typical grout used for back-filling the PVC conduit has a density ranging between 1,200 kg/m^3 and 1,450 kg/m^3. The grout mix recommended in the Backfilling Recommendations section of the ShapeArray Installation manual has a low density similar to the density of the PVC filled with chain.
It is important to weight the PVC down rather than allowing it to float up against a hard stop at the top. When the conduit is held from the top, buoyancy causes the conduit to bend and form S-curves making it difficult to insert the ShapeArray. It is recommended that the ShapeArray conduit be weighted down using chain to minimize buoyancy effects.
WARNING: Do not use water to weigh down the conduit. The water will make it difficult or impossible to insert the ShapeArray into the PVC due to hydraulic forces. If water egress is impeded, the attempt to insert the ShapeArray could lead to hydraulic pressure beyond the pressure ratings of the ShapeArray protective coverings.
Figure 5: Inserting chain to weigh down the PVC until the grout has cured
The included 1” Pipe Clamp (hanging fixture), should be attached to the PVC below the bottom half of the top stack assembly to ensure that the weighted conduit is suspended at the top of the borehole. Allow the grout to set for 24 hours prior to installing the ShapeArray.
Step 6 - Place the Reel Stand
Figure 6: Place the reel and reel stand approximately 1 m - 1.5 m from the borehole such that the ShapeArray comes off the top of the reel
Step 7 - Lower the ShapeArray Into the Casing
Step 8 - Settle the SAAV to Settle it into the Casing
Once the SAAV is resting on the bottom of the borehole, actions need to be taken to ensure it is properly settled in place. If the instrument is not properly settled in place prior to compressing it, then undesirable displacements will be reported by the instrument as it settles into place naturally. Settlement of the instrument within the casing is not reflective of movement of the casing or the surrounding environment.
To facilitate settling the instrument into place, the SAAV Installation Verification tool included in our SAARecorder software must be used. This tool will display a point graph where each point represents the tilt of a segment relative to the medial axis of the instrument's installed shape. More information on using this tool is available in the Verifying your SAAV Installation guide. Once you have your computer connected to the ShapeArray with the SAARecorder application, open the SAAV Installation Verification tool from the Diagnostics menu and take the following actions that are sometimes referred to as "pumping".
WARNING: If you are installing a ShapeArray in Low Power Mode for use with certain low power data loggers, then you will need to be using an SAAFPU interface with at least revision R.4B or an SAA232 interface with revision R.2B. Older interfaces are NOT supported. While the SAAV Installation Verification diagnostic is open, the instrument will temporarily be placed in regular power mode. When the SAAV Installation Verification window is closed, the instrument will automatically be returned to Low Power mode. Do NOT disconnect the ShapeArray from the computer without closing the window or the instrument could be left in regular power mode.
Lift the ShapeArray until it is hanging in the casing with one segment touching the bottom. When the last segment is resting on the bottom of the casing, the angle reported by the SAAV Installation Verification tool will be around 1°. The tilts of the segments above the last segment should be close to 0°. If there are bends in the borehole, the angle will increase to 1° or 2°. You should see a graph similar to what is shown in the figure below in the SAAV Installation Verification tool when the instrument has been lifted sufficiently.
Figure 7: The SAAV Installation Verification tool in SAARecorder when the SAAV has been lifted sufficiently
Once you have lifted the SAAV enough to have only the last segment resting on the bottom of the casing, drop the ShapeArray such that it falls straight into the casing. The array will drop into the hole with some friction from the joints resisting the movement. Manually apply some downward pressure to the SAAV (approximately 5 lbs) in order to compress it within the conduit, record the value for Compression reported in the SAAV Installation Verification tool, and collect sample data from SAARecorder.
The SAAV should be lifted and dropped repeatedly in this manner until three sequential readings of Compression do not change by more than 1 mm. This should take approximately 5 to 7 lift and drops (pumps).
WARNING: If you are using an older version of SAARecorder, you may see a green status light and other details listed in the window. In this version of the verification utility, the Average Tilt and green status light may be attained with fewer lift and drop operations; however, lifting and dropping the array should continue until the Actual Compression ceases to change by more than 1 mm on three consecutive drops.
NOTE: Save the recorded data files and details about the number of lift and drops were required to achieve proper compression. These files and details could be helpful in troubleshooting any issues encountered in the future.
Once this is done, you will be ready to measure the azimuth offset for the X-mark.
Step 9 - Find the Azimuth Offset from the X-Mark
The SAA X-Mark Protractor consists of two pieces: a square protractor with directional arrows and a clear plastic disk with an X-Line marked on it. Place the square protractor around the PEX at the top of the ShapeArray. Rotate the square protractor until the arrows are pointed to one of the following:
- The expected direction of movement
- Other desired heading of the ShapeArray
- Other job site datum
Figure 8: The square protractor placed around the PEX at the top of the ShapeArray
If the protractor needs to be placed over the PVC casing rather than the PEX, the required hole size is marked so it can be cut to fit.
Place the clear disk marker with the X-Line around the PEX on top of the square protractor. Rotate the clear disk around the ShapeArray until the X-Line on the disk and the X-Line on the PEX are aligned.
Figure 9: The clear disk aligned with the X-Lines on the ShapeArray and the square protractor
Make note of the azimuth offset angle at the X-Line. This will be directly used in the software to rotate the X-mark axis of the ShapeArray towards a known azimuth.
Step 10 - Use the Install Kit to Finish the Installation
Once the SAAV has been properly pumped and settled into the casing, the Install Kit should be used to complete the installation.
Apply downward force of no more than 20 kg (approximately 50 lbs) on the PEX and turn the set screws on the top stack with a Phillips screwdriver to maintain compression and orientation of the ShapeArray within the PVC.
NOTE: If the ShapeArray is installed in an area with heavy vibration or blasting, it is possible that the set screws will loosen with time. You should take steps to ensure that the set screws remain tight.
WARNING: Be careful. Over-tightening the set screws will strip the threads in the PVC.
Using the included PEX cutter, cut away any excess PEX tubing.
Figure 10: Cutting away excess PEX tubing
Use a small flat-headed screwdriver to remove the connector at the end of the ShapeArray cabling. Thread the top portion of the pre-assembled Install Kit over the cable and screw it into the bottom portion. Tighten the gland at the top of the top stack until the rubber gasket seals the cable. Make sure to remove the hanging fixture once the grout has set. Leaving it in place may lead to rotation.
Figure 11: The top portion of the pre-assembled Install Kit threaded over the cable and screwed it into the bottom portion
Step 11 - Run the Cable to a Data Acquisition System
Run cable to the data acquisition system. Use conduit to protect the cable and to ease cable replacement if required, as shown in Figure 13.A below. Since the PVC conduit containing the ShapeArray has been sealed, it is not necessary for the flexible conduit to cover the entire cable. If the top of the ShapeArray is protected using a well head covering or some other buried structure, it is possible to use zip ties provided in the kit to hold the conduit in place under the protective conduit. It is also possible to do cable splices or attach items such as the SAASPD surge protection device at this point, as shown in Figure 12.B below.
Figure 12: Running cable to a data acquisition system - (A) conduit to protect and ease cable placement, (B) SAASPD spliced onto the cable