Correlations of SPT, CPT and pressuremeter test data in alluvial soils. Case study: Tabriz Metro Line 2, Iran

The Menard pressuremeter modulus (E_m), limit pressure (P_L), shear modulus (G) and subgrade reaction modulus (K_s) can be obtained by using the pressuremeter test, and are needed as parameters to obtain the geotechnical parameters for foundation design and to determine the ultimate bearing capacity in engineering projects. In this article, correlations of Menard pressuremeter tests (PMTs) with standard penetration tests (SPTs) and cone penetration tests (CPTs) are obtained as a consequence of the extensive geotechnical investigation performed in alluvial soils of the Tabriz Metro Line 2, Iran. A total of 85 boreholes with depths of 20–40 m were drilled, and the three mentioned tests were performed at varying depths. Correlations were carried out separately for silty clay (CL), clayey silt (ML) and silty sand (SM) soils, respectively. Statistical correlations between E_m, P_L, G and K_s from the PMTs were performed with the corrected SPT numbers (N_cor). In addition, relationships between the limit pressure (P_L) from PMTs and cone resistance (q_c) from CPTs were determined for fine-grained and coarse-grained soils. Attempts were also made to correlate P_L with E_m, and E_m/P_L ratios. The results of this investigation indicated acceptable experimental regression relationships between these parameters. The comparisons between the measured and the predicted values of E_m and P_L obtained herein with those estimated from other equations that have been proposed by other researchers revealed that they are compatible. It can be concluded that the proposed relationships for fine-grained and coarse-grained soils can be utilized to determine E_m, P_L, G and K_s from the N_cor values and P_L from the q_c values.