Soil Creep Behavior from Modified Pressuremeter Tests

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4. Soil Creep Behavior from Modified Pressuremeter Tests

The pressuremeter test is a widely used in situ method to characterize the mechanical properties of soils. It is based on the controlled radial expansion of a probe inserted into a pre-drilled borehole, allowing for the measurement of the stress-strain relationship of the soil. According to the NF EN ISO 22476-4 standard, each loading stage is maintained for 60 seconds. This study analyzes the impact of extending this duration to 120 seconds on the results of pressuremeter tests. Standard Pressuremeter Tests (PMT) and Modified (MPMT) Pressuremeter Tests were conducted on different types of soils from four sites in Tunisia, including soft clays, sandy clays, fine sands, and highly compacted soils (stiff clays and dense sands). The results show that deformations persist beyond 60 seconds, leading to significant reductions in limit pressure (P_l*) and creep pressure (P_f*), as well as a decrease in the pressuremeter modulus (E_M). These reductions become more pronounced as the compressibility index (C_c) increases. Additionally, a significant increase in the creep coefficient ( )  which in a key indicator of time-dependent deformations in the pseudo-elastic zone, is observed in fine and low-consistency soils, Whereas, for highly compacted sands and stiff clays, the creep coefficient remains stable. This coefficient highlights the interaction between creep and primary consolidation.

8th International Symposium on Pressuremeters (ISP2025)

Pressuremeter Testing Techniques and procedures