Recent developments in equipment and interpretation of cone penetration test for soil characterization

Over the last decades cone penetration testing has become the most widely used in-situ testing technique for stratigraphic profiling and site characterization. As a consequence of such extensive use, which has also rapidly spread to many new areas of application, a considerable amount of research has been carried out in terms of equipment, testing procedures, analysis of the penetration mechanisms and methods for data interpretation. This paper aims at providing a general picture of the major trends in CPT research carried out over the recent years, by presenting the most significant emerging innovations in instrumentation and the latest advances in the analysis of tests on sediments other than \u201cstandard\u201d clays and sands and thus referred to as \u201cnon-standard\u201d or \u201cunusual\u201d geomaterials. Attention is especially focused on intermediate sediments, such as silts, sandy silts, clayey sands and other sedimentary soils having very scattered grain size distributions and therefore potentially affected by partial drainage effects during cone penetration tests. The body of knowledge on such effects, as accumulated worldwide from both laboratory and field research, is reviewed and discussed, with special emphasis on the experimental results obtained from variable rate piezocone tests carried out in a few intermediate soil deposits in northern Italy. It is shown that the efforts of many researchers have mainly focused on the identification of cone penetration velocities required to ensure fully drained or fully undrained testing conditions, with reference to different soil classes or macrofabrics. Indeed, the preliminary identification of drainage conditions is a key step in order to avoid misinterpretation of field measurements and thus to develop interpretation procedures that could lead to a rational selection of soil parameters and economical design

Developing a regional-scale geotechnical model of the North-Western Adriatic coastal area (Italy) for urban planning and robust geotechnical design

The paper presents a study for the development of a regional-scale geotechnical model of the coastal plain facing the Adriatic Sea, in the south-eastern margin of the Emilia-Romagna Region (Italy). This area is a well-known, heavily urbanized touristic site in Italy, very famous for its wide sandy beaches. The information provided by a large experimental database, consisting of boreholes and piezocone tests, coupled with details on the recent sedimentary evolution of the shallow subsurface, was used to develop a stratigraphic model of the upper 30m subsoil and to obtain a geotechnical characterization of the different soil units. Such accurate geotechnical characterization may be useful to geotechnical engineers working in this area or similar geological environments, in terms of representative values of soil parameters, guidelines for better design of geotechnical investigations, identification of issues peculiar to data interpretation and recognition of potential geotechnical problems. A similar study may result in a useful tool for urban planning and robust geotechnical design

Full-scale testing of liquefaction mitigation using Rammed Aggregate Piers in silty sands.

Liquefaction mitigation in silty sands is a major challenge for geotechnical engineers, specialty contractors, and owners. An extensive literature is available for studying densification of vibratory methods whose effectiveness decrease as the fines content increases, while few information are known on the increment of lateral pressure and of the composite stiffening response of piers. In this respect, a full-scale testing was performed in Bondeno (Ferrara, Italy) where liquefaction was observed in the 2012 Emilia earthquake. In this study, ground improvement in silty sand, produced by a group of 16 Rammed Aggregate Piers (RAP), was tested using in situ tests and controlled blasting. An adjacent untreated test area with no RAPs, which experienced liquefaction and significant settlement (70 to 100 mm) following controlled blasting, was also characterized for useful comparison. Relatively high excess pore pressure ratios were recorded in both the panels, while the measured settlement (20 to 40 mm) in the improved panel was significantly lower than in the unimproved panel and sand boils did not develop

Analysis and monitoring of a tunnelling-induced deep landslide reactivation

Landslides are often triggered or accelerated by human activities, such as tunnel excavation, that can induce extensive damages to the undercrossed structures and infrastructures. The case-study presented and discussed in this paper concerns a huge slow landslide temporarily reactivated by the excavation of twin tunnels for the motorway crossing the Apennines between Bologna and Florence (Italy). The large amount of monitoring data collected before and during the excavation allowed a clear identification of the landslide displacement trends along with the tunnel progressing, both at the ground surface and at the deep sliding interface. The rather articulated monitoring data have been interpreted using a finite element model that seems to be capable to describe the horizontal displacement trends during all the phases of tunnel excavation

Blast-induced liquefaction in silty sands for full-scale testing of ground improvement methods: Insights from a multidisciplinary study

In the engineering geology field increased attention has been posed in recent years to potential liquefaction mitigation interventions in susceptible sand formations. In silty sands this is a major challenge because, as the fines content increases, vibratory methods for densification become progressively less effective. An alternative mitigation technique can be the installation of Rammed Aggregate Pier\uae (RAP) columns that can increase the resistance of the soil, accounting for its lateral stress increase and for the stiffness increase from soil and RAP composite response. To investigate the influence of these factors on liquefaction resistance, full-scale blast tests were performed at a silty sand site in Bondeno (Ferrara, Italy) where liquefaction was observed after the 2012 Emilia-Romagna earthquake. A multidisciplinary team of forty researchers carried out devoted experimental activities aimed at better understanding the liquefaction process at the field scale and the effectiveness of the treatment using inter-related methods. Both natural and improved areas were investigated by in-situ tests and later subjected to controlled blasting. The blast tests were monitored with geotechnical and geophysical instrumentation, topographical surveying and geological analyses on the sand boils. Results showed the RAP effectiveness due to the improvement of soil properties within the liquefiable layer and a consequent reduction of the blast-induced liquefaction settlements, likely due to soil densification and increased lateral stress. The applied multidisciplinary approach adopted for the study allowed better understanding of the mechanism involved in the liquefaction mitigation intervention and provided a better overall evaluation of mitigation effectiveness

Transverse momentum spectra of charged particles in proton-proton collisions at 1as=900 GeV with ALICE at the LHC

The inclusive charged particle transverse momentum distribution is measured in proton-proton collisions at s=900 GeV at the LHC using the ALICE detector. The measurement is performed in the central pseudorapidity region (|\u3b7|<0.8) over the transverse momentum range 0.15<10 GeV/c. The correlation between transverse momentum and particle multiplicity is also studied. Results are presented for inelastic (INEL) and non-single-diffractive (NSD) events. The average transverse momentum for |\u3b7|<0.8 is \u3008pT\u3009INEL=0.483\ub10.001 (stat.)\ub10.007 (syst.) GeV/c and \u3008pT\u3009NSD=0.489\ub10.001 (stat.)\ub10.007 (syst.) GeV/c, respectively. The data exhibit a slightly larger \u3008pT\u3009 than measurements in wider pseudorapidity intervals. The results are compared to simulations with the Monte Carlo event generators PYTHIA and PHOJET. \ua9 2010

J/\u3a8 production and nuclear effects in p-Pb collisions at 1asNN=5.02 TeV

Inclusive J/\u3a8 production has been studied with the ALICE detector in p-Pb collisions at the nucleon-nucleon center of mass energy 1asNN = 5.02TeV at the CERN LHC. The measurement is performed in the center of mass rapidity domains 2.03 < ycms < 3.53 and ?4.46 < ycms < ?2.96, down to zero transverse momentum, studying the \u3bc+\u3bc? decay mode. In this paper, the J/\u3a8 production cross section and the nuclear modification factor RpPb for the rapidities under study are presented. While at forward rapidity, corresponding to the proton direction, a suppression of the J/\u3a8 yield with respect to binary-scaled pp collisions is observed, in the backward region no suppression is present. The ratio of the forward and backward yields is also measured differentially in rapidity and transverse momentum. Theoretical predictions based on nuclear shadowing, as well as on models including, in addition, a contribution from partonic energy loss, are in fair agreement with the experimental results

Comparison of runaway electron generation parameters in small, medium-sized and large tokamaks - A survey of experiments in COMPASS, TCV, ASDEX-Upgrade and JET

This paper presents a survey of the experiments on runaway electrons (RE) carried out recently in frames of EUROFusion Consortium in different tokamaks: COMPASS, ASDEX-Upgrade, TCV and JET. Massive gas injection (MGI) has been used in different scenarios for RE generation in small and medium-sized tokamaks to elaborate the most efficient and reliable ones for future RE experiments. New data on RE generated at disruptions in COMPASS and ASDEX-Upgrade was collected and added to the JET database. Different accessible parameters of disruptions, such as current quench rate, conversion rate of plasma current into runaways, etc have been analysed for each tokamak and compared to JET data. It was shown, that tokamaks with larger geometrical sizes provide the wider limits for spatial and temporal variation of plasma parameters during disruptions, thus extending the parameter space for RE generation. The second part of experiments was dedicated to study of RE generation in stationary discharges in COMPASS, TCV and JET. Injection of Ne/Ar have been used to mock-up the JET MGI runaway suppression experiments. Secondary RE avalanching was identified and quantified for the first time in the TCV tokamak in RE generating discharges after massive Ne injection. Simulations of the primary RE generation and secondary avalanching dynamics in stationary discharges has demonstrated that RE current fraction created via avalanching could achieve up to 70-75% of the total plasma current in TCV. Relaxations which are reminiscent the phenomena associated to the kinetic instability driven by RE have been detected in RE discharges in TCV. Macroscopic parameters of RE dominating discharges in TCV before and after onset of the instability fit well to the empirical instability criterion, which was established in the early tokamaks and examined by results of recent numerical simulations