Published: 28 June 2019
Logical and non logical answer is a big NO. But indeed is exactly what we do based on the formulas, models, etc. The loading tests are a significant improve in the design support but, again, limited to the tested elements. So, what to do in heterogenic soils where the soil investigation is, as frequently, not enough?
We have a wide experience systems that provide information for the 100% of the elements (piles or anchors) measuring actual parameters of the soils at the tip level. Those systems are the Expander Body® and the Toe Box®. The first is an exoandable steel "baloon" instaled at the tip of each element. Once the concrete of the shaft is hard, the EB is expanded with grout injection, increasing the diameter of the tip up to 800 mm, compacting the soil and preconsolidating the soil. The following papers explains better the process:
https://www.academia.edu/6027307/THE_USE_OF_THE_EXPANDER_BODY_WITH_CAST_IN_SITU_PILES_IN_SANDY_SOILS
https://www.academia.edu/9508510/RESPONSE_TO_LOAD_FOR_FOUR_DIFFERENT_TYPES_OF_BORED_PILES
For the toe box, in page 209 of the following link, is a paper explaining how it works:
http://www.cfpbolivia.com/getfile.ashx?cid=576847&cc=3&refid=1
Basically is a load cell with up to 300 mm of vertical dispalcement, installed at the toe of a drilled shaft. Once the concrete is hardened, the cell is verticaly expnaded with grout. During the process, the peessures and volume are recorded together with the movement of the bottom plate (meassured in surface with wo tell tales). So, at the end, all the debris and the natural soil are compacted and the total force measured.
The two presented systems have been used in hundred of projects, giving a high reliability and allowing not only the optimization of designs but alse economy, less construction time and a very high QA/QC, beside the direct measurement of geotechnical parameters
Categories
Deep Foundations, Shallow Foundations
Keywords
Soil, Deep Foundations, Ground Improvement