Rock Slope Stabilization Quality Control/Quality Assurance

Preferred QC/QA Procedures

<h2>Preferred QC/QA Procedures</h2> Due to the uniqueness of each rock slope stabilization method or situation, individual components of reinforcement technologies have their own governing QC/QA procedures. The methods of rock slope stabilizations fall into the categories of altering slope geometry, installing drainage, and adding reinforcement. Altering the slope consists of trimming, blasting, and scaling. The extent of QC/QA procedures for these methods is a visual inspection by the design engineer. The QC/QA procedure for drainage consists of groundwater pressure tests. QC/QA for reinforcement techniques are unique to the reinforcement technology chosen and will be discussed further in detail. Quality control and quality assurance procedures will be addressed for rock bolts, tieback walls, and shotcrete. The standard method for rock bolts is the Pull Test described by ASTM D4435. This test measures the load a rock bolt is under as well as any displacement observed during the testing process. For tiebacks, the standard quality control and quality assurance procedure is a performance test measuring load and creep under PTI DC35.1-14. The previous two reinforcement methods require grout which the compressive strength must be quality tested following ASTM D4380. Shotcrete quality testing includes testing the compressive strength of core samples under ACI 506.4R-94 as well as testing the ability of the nozzleman using core grades under ACI 506.2-95. Construction quality is achieved by meeting established requirements, as detailed in project plans and specifications, including applicable codes and standards.  Quality Control (QC) and Quality Assurance (QA) are terms applied to the procedures, measurements, and observations used to ensure that construction satisfies the requirements in the project plans and specifications.  QC and QA are often misunderstood and used interchangeably.  Herein, Quality Control refers to procedures, measurements, and observations used by the contractor to monitor and control the construction quality such that all applicable requirements are satisfied.  Quality Assurance refers to measurements and observations by the owner or the owner's engineer to provide assurance to the owner that the facility has been constructed in accordance with the plans and specifications. Table 1 shows the components of QC/QA monitoring programs for Rock Slope Stabilization.  The entries in the table are a list of typical items, not a list of all methods that could be used for QC/QA.  Some QC procedures and measurement items may also serve as QA procedures and measurement items.       Table 1.  Typical components of QC/QA monitoring programs. <table class="tablepress"> <tbody> <tr> <td colspan="3" width="200"> Topics </td> <td width="380"> Items </td> </tr> <tr> <td rowspan="4" width="103"> Existing QC/QA Procedures & Measurement Items </td> <td rowspan="2" width="24"> QC </td> <td width="73"> Material Related </td> <td width="380"> Shotcrete/grout compressive strength Grout specific gravity Tieback creep </td> </tr> <tr> <td width="73"> Process Control </td> <td width="380"> Random sampling </td> </tr> <tr> <td rowspan="2" width="24"> QA </td> <td width="73"> Material Related </td> <td width="380"> Shotcrete/grout compressive strength Rock bolt load Rock bolt displacement Tieback creep </td> </tr> <tr> <td width="73"> Process Control </td> <td width="380"> Nozzleman core grades Proof/verification testing </td> </tr> <tr> <td rowspan="2" width="103"> Performance Criteria </td> <td colspan="2" width="97"> Material Parameters </td> <td width="380"> Rock bolt deformation Uniformity of shotcrete </td> </tr> <tr> <td colspan="2" width="97"> System Behavior </td> <td width="380"> Creep monitoring pressure monitoring </td> </tr> <tr> <td rowspan="2" width="103"> Emerging QC/QA Procedures & Measurement Items </td> <td colspan="2" width="97"> Material Related </td> <td width="380"> Ground Anchorage Integrity Testing (GRANIT) Wave propagation through rock bolts </td> </tr> <tr> <td colspan="2" width="97"> Process Control </td> <td width="380"> None noted </td> </tr> </tbody> </table>

QC/QA Guidelines

<h2>QC/QA Guidelines</h2> With each testing parameter, the following notes should be considered: <ul> <li>Shotcrete testing requires a test panel for mixing proportions. 3 test specimens with reinforcement and 3 without reinforcement are taken (ACI Committee 506, 1995).</li> <li>1 specimen is required for each batch of rock bolt or tieback grout (PTI Committee DC35, 2014).</li> <li>Rock bolts must be tested in each rock type, at each orientation, and for each system until 95% confidence in the loading capacity is achieved (ASTM 4435, 2013).</li> <li>2% of tiebacks installed are subjected to creep testing (PTI Committee DC35, 2014).</li> </ul> Inspections, construction observations, daily logs, and record keeping are essential QC/QA activities for all technologies.  These activities help to ensure and/or verify that: <ul> <li>Good construction practices and the project specifications are followed.</li> <li>Problems can be anticipated before they occur, in some cases.</li> <li>Problems that do arise are caught early, and their cause can oftentimes be identified.</li> <li>All parties are in good communication.</li> <li>The project stays on schedule.</li> </ul>

References

<h2>References</h2> ACI Committee 506. (1994). Guide for the Evaluation of Shotcrete (pp. 1-3, Standard. No. ACI 506.4R-1). Farmington Hills, MI: American Concrete Institute. ACI Committee 506. (1995). Specification for Shotcrete (pp. 1-5, Standard. No. ACI 506.2). Farmington Hills, MI: American Concrete Institute. ASTM D4380. (2012). Standard Test Method for Density of Bentonitic Slurries (pp. 1-2, Standard. No. D4380-12). West Conshohocken, PA: ASTM International. ASTM D4435. (2013). Standard Test Method for Rock Bolt Anchor Pull Test (pp. 1-6, Standard. No. D4435-13). West Conshohocken, PA: ASTM International. Farnsworth, C. B., Leonard, B., & Sjoblom, D. (2010). Quality Assurance of Soil Nail Grout for Provo Canyon Reconstruction Project. Earth Retention Conference 3. doi:10.1061/41128(384)26 Fishman, K. L., Withiam, J. L., & Jackson, B. H. (2005). GEO Construction Quality Assurance/Quality Control Technical Conference. In A Recommended Practice for Condition Assessment of Ground Anchors and Soil Nails. Hanskat, C. (2011). Shotcrete Testing— Who, Why, When, and How (pp. 1-5, Rep.). Nashville, TN: American Shotcrete Association. Ivanović, A., Starkey, A., Neilson, R. D., & Rodger, A. A. (2003). The influence of load on the frequency response of rock bolt anchorage. Advances in Engineering Software, 34(11-12), 697-705. doi:10.1016/s0965-9978(03)00099-1 Kılıc, A., Yasar, E., & Celik, A. (2002). Effect of grout properties on the pull-out load capacity of fully grouted rock bolt. Tunnelling and Underground Space Technology, 17(4), 355-362. doi:10.1016/s0886-7798(02)00038-x Kutschke, W. G., Petersen, W., & Meyers, J. (2007). Rock Slope Protection System for Differential Weathering Materials. Embankments, Dams, and Slopes. doi:10.1061/40905(224)9 NYSDOT. (2020). Standard Specifications (Vol. 2, pp. 82-397, Rep.). Albany, NY: New York State Department of Transportation. Oregon DOT. (2020). Oregon Standard Specifications for Construction (pp. 276-320, Rep.). Salem, OR: Oregon Department of Transportation. PTI Committee DC35. (2014). Recommendations for Prestressed Rock and Soil Anchors (pp. 65-83, Standard. No. DC35.1-14). Farmington Hills, MI: Post-Tensioning Institute. Schuster, R. L., & Turner, A. K. (1996). Chapter 18 Stabilization of Rock Slopes. In Landslides: Investigation and mitigation (pp. 474-504). Washington, DC: National Academy Press. Wyllie, D. C., Mah, C. W., Hoek, E., & Bray, J. (2009). Rock Slope Engineering - Civil and Mining. New York, NY: Spon Press.

Technology

Rock Slope Stabilization