<p><p><strong>Reference(s):</strong></p><p><em>Bandimere (1997)<br>Byle (2000)<br>Geraci (2007)<br>Graf (1992)<br>Gularte et al. (2007)<br>Haramay et al. (2009)</em></p><p><strong>Method Summary</strong></p><p>The active construction monitoring method is primarily an observational method. It involves a technician actively monitoring the grouting procedures taking place, recording the relevant data, and assuring it meets the project requirements. Monitoring typically includes the following parameters:<br><ul> <li>Volume of grout take</li> <li>Pressures in the grout pipe</li> <li>Flow rate in the grout pipe</li> <li>Heave of the ground surface</li> <li>Tilt/heave of surrounding structures</li> <li>Testing slump of grout mix (ASTM C143)</li></ul>The equipment typically used in the past for construction monitoring has been calibrated gauges on the equipment and counting the strokes of the grout pump to estimate volumes. However, the use of equipment such as a Flowlogger has become more prevalent. This is more accurate and advantageous due to the ability to collect real time data, analyze it on site, and send it to an engineer in the office immediately. Tilt meters and survey points can be placed in the surrounding area to monitor the effects on the ground surface and any surrounding structures. Wireless technology has made this much simpler to implement within recent years. The equipment should be accurate to within 1% and tested to ensure that it cannot give false readings.</p><p>Refusal is monitored and recorded by the technician and confirmed by the engineer. Stopping criteria can vary depending on the scope of the project but typically includes the following:<br><ul> <li>Critical grout pressure</li> <li>Maximum volume of grout per stage</li> <li>Excessive heave of the ground surface and tilt of surrounding structures</li> <li>A sudden drop in pressure indicating hydraulic fracturing</li></ul>Secondary and tertiary grout injections are monitored to ensure that they indicate densification occurred due to the primary injection. Higher pressures and lower volume takes are indicative that this has occurred. Grouting equipment should be checked prior to construction. Hoses and fittings should be free of obstructions and leaks. The pump should be tested prior to pumping the first injection.</p><p><strong>Accuracy and Precision</strong></p><p>The procedures of this method cannot directly depict the behavior of the compaction grout in the ground. It does give an indication as to the quality of work completed based upon which stopping criteria is met and the grout takes and pressures of the secondary and tertiary injections.</p><p><strong>Adequacy of Coverage</strong></p><p>There is no direct way to determine if the areas targeted were actually improved. However, this procedure can be employed over the entire site and typically it is very easy to cover a large area. The location of the grout injections may be recorded and inferences may be made based upon theory of the radial stress dissipation.</p><p><strong>Implementation Requirements </strong></p><p>This method is relatively easy to implement. A technician and monitoring equipment are the only things necessary.</p><p><strong>General Comments</strong></p><p>This method should be used in almost all applications. While other methods, based more upon end results should be emphasized, these methods should not be abandoned. They are fairly well proven in the field and have been used fairly successfully for many years.</p></p>