On the influence of overconsolidation effect on the compressibility assessment of subsoil by means of CPTU and DMT

Abstract

The paper contains the analysis of the influence of overconsolidation effect on the values of constrained moduli, assumed by means of two most popular in situ advanced tests. The tested soils included two geological formations: normally consolidated tills of the Pomeranian phase and overconsolidated tills of the Posnanian phase. The overconsolidation ratio (OCR) was derived from CPTU, DMT and oedometric tests. The tests revealed that for the assessment of changes in constrained modulus in the subsoil with CPTU and DMT, the formulas determining the relationship between cone resistance, DMT results and constrained moduli requires empirical coefficient different for soils of varied genesis.

Evaluation of the Undrained Shear Strength in Preconsolidated Cohesive Soils Based on the Seismic Dilatometer Test

“…Plots of regression lines (13) and (14) with 95% confidence intervals are given in Figure 8. The simple linear regression models (15) and (16) shown in Table 6 gave worse accuracy.…”

“…The index properties of the tested soils for three undisturbed soil samples (No. [14][15][16] are shown in Table 2. The glacitectonically disturbed Pliocene clays are preconsolidated with the overconsolidation ratio, OCR, increasing with depth from 5 to 8.…”

“…Comprehensive studies have been performed to improve some of the original correlations proposed by Marchetti. Numerous investigations have been made to expand the application of DMT in geotechnical engineering [8][9][10][11][12][13][14][15][16][17]. In most cases, the relationships used to evaluate geotechnical parameters from the dilatometer test such as the corrected first pressure 2 of 19 reading p o or the corrected second pressure reading p 1 , or index parameters such as the material index I D , horizontal stress index K D , and dilatometer modulus E D , are commonly applied.…”

Evaluation of correlation between parameters from CPTU and DMT tests and soil type behavior chart

“…An example is the description of continuous changes in undrained shear strength in the sublayer using the parameter from the CPTU test and supplementing this information in places where only the DMT test was performed. In the case of subsoil from Poland, these dependencies have significant limitations to the dependencies proposed in the world literature (Lechowicz et al 2011, Młynarek et al 2016, 2017, 2018. With such limitations one should also count in relation to the functional relationship between the parameters q t and K D .…”

Determination of undrained shear strength and constrained modulus from DMT for stiff overconsolidated clays

“…Comprehensive investigations were made to assess and enlarge the application of DMT in geotechnical engineering (Lutenegger 1988, Powell and Uglow 1988, Lunne et al 1989, 2006, Monaco and Marchetti 2004, Schnaid 2009, Cao et al 2015, Robertson 2015, Silvestri and Tabib 2015, Młynarek et al 2016). However, in most relationships used to evaluate constrained modulus (Briaud and Miran 1991) Roque et al (1988) proposed an alternative approach for estimating undrained shear strength based on the correlation using p 1 readings and bearing capacity factor (N c ).…”