The end bearing capacity of drilled shafts is typically reduced due to the massive displacement required to mobilize ultimate capacity. Consequently, a large portion of the ultimate capacity necessarily goes unused. Mechanistic procedures to integrate its contribution have been developed by pressure grouting beneath the shaft tip to regain some of this unusable capacity. The process is known as Post Grouting or Base Grouting or Tip Grouting.
By design, the grout distribution system provides a known pressurizing surface area. Therefore, the end bearing, and upward skin friction load are determined to a level proportional to the applied grout pressure. Quantitative data about the load-carrying capability of every production shaft is obtained, thereby increasing the performance of the structure.
The post grouting process entails:
- Installation of a grout distribution system during cage preparation that provides grout tube-access to the bottom of the shaft
- After the shaft concrete is cured, injection of high-pressure grout beneath the tip of the shaft takes place, and densifies the in-situ soil and compresses any debris left by the drilling process
AFT is pioneering the use of this revolutionary procedure and is at the core of a team that has developed a proven systematic approach to post grouted shaft design and implementation. We have post grouted more drilled shafts in the United States than any other company. In most cases, the method was used as a cost-saving alternative to conventional drilled shafts or to replace competing foundation systems.
We bring our technological edge to post grouting with our proprietary GroutDAQ™ system. This procedure uses embedded and top of shaft instrumentation to develop a complete electronic testing regimen to the post grouting process. With our unrivaled experience and technology, AFT can give your drilled shafts a renewed competitive edge in the foundation construction industry.