Field Test Verification of Ground Bearing Pressure Under Rig Tracks and Implications for Working Platform Design-PPT Presentation

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The study investigates how ground-bearing pressure (GBP) beneath the tracks of geotechnical rigs should be calculated and how those pressures affect working-platform design. It compares conventional approaches, including the equal-eccentricity method, with Liebherr’s Ground Pressure Visualisation (GPV) method and an auxiliary method developed by the authors.<br /><br />Field measurements were taken using a GPV system installed on an LRB 125XL rig. The measured pressures were compared with calculations based on an elastic half-space model and three-dimensional finite-element analysis. The tests also highlighted the importance of accurately determining the track length in contact with the ground.<br /><br />The authors find that assuming the left and right tracks have the same load eccentricity as the overall resultant can produce either an overestimate or an unsafe underestimate of GBP, depending on the leader’s position and the eccentricity. They recommend using a method that represents the track-load distribution more accurately, such as GPV. They also conclude that the contact length should reflect track settlement under load and therefore the stiffness of the working platform, rather than relying on the simplified recommendation in EN 16228-1.<br /><br />Revised pressure distributions can lead to lower calculated ultimate bearing capacity of the supporting soil than conventional methods suggest. Consequently, platforms designed using conventional assumptions may be less secure than their calculations indicate. The authors recommend further research that moves beyond the rigid-track model, which could also remove the need for separate rules on variable track contact length.

Keywords

ground-bearing pressure

working-platform design

geotechnical rigs

track load eccentricity

Ground Pressure Visualisation

elastic half-space model

finite-element analysis

track settlement

bearing capacity

working platform stiffness