Soil Liquefaction Hazard Evaluation by the New Seismic Dilatometer Marchetti Test （SDMT）

Soil liquefaction, and the permanent deformations that frequently result from it, have caused significant damage in past earthquakes. The procedures used in contemporary geotechnical earthquake engineering practice are generally based on simplified procedures for the evaluation of the liquefaction potential. The work describes a framework for performance-based earthquake engineering and its use in the development of a performance-based procedure for liquefaction hazard evaluation. The performance-based procedure will be used to show how consistent application of conventional procedures for evaluation of liquefaction potential can influence performance prediction. Implications for liquefaction-resistant design will also be discussed. The purpose is to summarize current procedures for practical prediction of liquefaction behavior, to describe recent advances in the understanding of liquefaction behavior, and to describe the incorporation of this improved understanding into new solutions for detailed modeling of soil liquefaction, Simplified procedures for evaluation of liquefaction hazards will be reviewed relatively briefly, with more details devoted to emerging knowledge about the mechanics of liquefiable soil behavior, and methods for incorporating those mechanics into improved models for performance prediction. In particular it focuses about the influence on the evaluation of Cyclic Resistance Ratio （CRR） by different in-situ tests （Cone Penetration Test （CPT）. Standard Penetration Test （SPT） and Seismic Dilatometer Marchetti Test （SDMT）） and by different shear waves velocity measurements （Down Hole D-H. Cross Hole C-H, Seismic Dilatometer Marchetti Test SDMT）.

In Situ Tests--Predicted vs. Observed Settlements： A Comparative Case Study

This paper aims to deal with the comparison of the estimated settlements derived by in situ tests with the observed settlements in site, in order to evaluate the accuracy of settlement prediction by in situ tests, in comparison not only with site observation by topographic means, but also with the values of settlements derived by numerical analysis by means of PLAXIS 2D and 3 D. The site where are carried out the tests and periodically are observed the settlements since the beginning of construction process, is located in the Oil Product Terminal, at the industrial park of Porto Romano, Durres, Albania. The main purpose of this project was the ground improvement by using preloading method in order to prevent liquefaction process and settlements. The data used to conduct this study are taken by the site investigation done after inserting into the soil vertical drains made of columns of free--draining gravel （gravel pile drains） until 14 m depth and center-to-center spacing of 2 m, and wick drains （premanufactured） until 25 m depth and center-to-center spacing of 1.8 m. The observed settlements are periodically measured by topographic equipments. This paper will present the conclusions derived by settlement analyzes from in situ tests and site observations.

The Role of Soil Investigation on Performance-based Design in Geotechnical Earthquake Engineering

The spatial variability of geotechnical earthquake engineering critical parameters obtained by laboratory and in situ tests in the same area is affected by different measurements. The paper provides a brief synthesis of ground motion and site effects analysis procedures within a Performance-Based Design framework. In particular it focuses about the influence on the evaluation of site effects in some active regions by different shear waves velocity measurements （Down Hole D-H and Seismic Dilatometer Marchetti Test SDMT）. Moreover the variation of shear modulus and damping ratio with strain level and depth from different laboratory dynamic or cyclic tests for soil characterisation （Resonant Column Test RCT） was evaluated. The available data enabled one to compare the shear waves velocity profile obtained by laboratory and in situ tests （Cone Penetration Tests CPT） with empirical correlations proposed in literature.

Pressure-controlled elliptical cavity expansion under anisotropic initial stress: Elastic solution and its application

This paper presents an elastic solution to the pressure-controlled elliptical cavity expansion problem under the anisotropic stress conditions. The problem is formulated by the assumption that an initial elliptical cavity is expanded under a uniform pressure and subjected to an in-plane initial horizontal pressure Kσ_0 and vertical pressure σ_0 at infinity. A conformal mapping technique is used to map the outer region of the initial elliptical cavity in the physical plane onto the inner region of a unit circle in the phase plane. Using the complex variable theory, the stress functions are derived; hence, the stress and displacement distributions around the elliptical cavity wall can be obtained. Furthermore, a closed-form solution to the pressure-expansion relationship is presented based on the elastic solution to the stress and displacement. Next, the proposed analytical solutions are validated by comparing with the Kirsch's solution and the finite element method(FEM). The solution to the presented pressure-controlled elliptical cavity expansion can be applied to two cases in practice. One is to employ the solution to the interpretation of the shear modulus of the soil or rocks and the in-situ stress in the pre-bored pressuremeter test under the lateral anisotropic initial stress condition. The other is the interpretation of the membrane expansion of a flat dilatometer test using the pressure-controlled elliptical cavity expansion solution. The two cases in practice confirm the usefulness of the present analytical solution.

Examination of DMT-based methods for evaluating the liquefaction potential of soils

The flat dilatometer test （DMT） has the potential to be a useful tool in the evaluation of liquefaction potential of soils. In practice, it is necessary to carefully examine existing DMT-based methods for evaluating liquefaction potential. We con- ducted the DMT and cone penetration test （CPT） in high liquefaction potential areas to examine the existing DMT-based methods for liquefaction potential evaluation. Specifically, the DMT and CPT were conducted side-by-side at each of six in-situ sites, and thus it is feasible to utilize those test results to validate the existing DMT-based methods. The DMT parameter, horizontal stress index （KD）, is used as an indicator for estimating liquefaction resistance of soils in terms of cyclic resistance ratio （CRR）. The analysis results revealed that the existing KD-based liquefaction evaluation methods would overestimate the CRR of soils, which leads to overestimation of the factor of safety against liquefaction. Also, the estimations of DMT-KI~ values by using the CPT-qc as well as the correlation between DMT-KD and CPT-qc proposed by the previous studies would be significantly smaller than field measurements. The results reflected that further validation of the existing DMT-based methods for liquefaction evaluation is desirable.

Prediction of the shear wave velocity Vs from CPT and DMT at research sites

The paper examines the correlations to obtain rough estimates of the shear wave velocity Vs from non- seismic dilatometer tests （DMT） and cone penetration tests （CPT）. While the direct measurement of Vs is obviously preferable, these correlations may turn out useful in various circumstances. The experimental results at six international research sites suggest that the DMT predictions of Vs from the parameters ID （material index）, KD （horizontal stress index）, MDMT （constrained modulus） are more reliable and consistent than the CPT predictions from qc （cone resistance）, presumably because of the availability, by DMT, of the stress history index KD.