MPM simulations of the impact of fast landslides on retaining dams

Possible protection systems against flow-like landslides are earth dams built to stop or deviate the flow. The evaluation of impact forces on the structures is still based on oversimplified empirical approaches, which may lead to a very conservative design, with high costs and environmental impact. Numerical methods able to capture the essential features of the phenomenon can offer a valuable tool to support the design of protection measures. This paper shows the potentialities of the Material Point Method (MPM) in this field. A dry granular flow, modelled with the Mohr-Coulomb model is considered. The landslide is placed in front of the barrier with a prescribed velocity and the impact forces on the slanted face is monitored with time

Analysis of piezocone penetration under different drainage conditions with the two-phase Material Point Method

The piezocone penetration test (CPTU) is commonly used to identify the soil profile and to estimate material properties. Depending on the soil type, ranging from clay to sand, undrained, partially drained or drained conditions may occur during cone penetration. In silt and sand-clay mixtures the CPTU penetration is characterized by partially drained conditions, which are often neglected in data interpretation. The effect of drainage on CPTU measurements has been mainly studied experimentally. Numerical analyses are rare because taking into account large soil deformations, soil-water and soil-structure interactions, as well as non-linear soil behaviour is still a challenging task. This paper presents and discusses numerical simulations of CPTU in saturated soils with the two-phase Material Point Method. Soil behaviour is described with the Modified Cam Clay model. This study investigates the effects of pore pressure dissipation during penetration, cone roughness and horizontal stress state, comparing the results with experimental data. The paper discusses the effect of neglecting partial drainage in deriving the shear strength parameters for silty soils and suggests a procedure to estimate the consolidation coefficient performing CPTU at different penetration rates

Behaviour of micropiles in heterogeneous coarse soils

This paper reports on an experimental investigation on the behaviour of small-diameter piles, commonly referred to as micropiles. This particular type of deep foundation is frequently used in many barely accessible Italian mountainous areas, often characterised by complex ground profiles composed of mixtures of coarse soils with some fine matrix elements including cobbles and large-diameter boulders. In such ground conditions, the lack of reliable site and laboratory geotechnical investigations providing an accurate soil mechanical description and conservative approaches for micropile design often lead to significant underestimation of the vertical ultimate load. In order to improve micropile design in such geological contexts, a new field trial investigation involving tension and compression load tests on micropiles up to failure was set up in a selected test site located in the Italian alpine region. From interpretation of the load tests carried out so far, the reliability of commonly used calculation methods for estimating bearing capacity is discussed. As a result, a new approach for a more suitable calculation of the mobilised shaft and base resistance of micropiles bored in highly coarse soils is tentatively propos

Numerically based design of protection systems against landslides. Workshop Numeric in Geotechnology

fast flow-like landslides are the one of the most dangerous natural hazards. Rigid or flexible structures are often used to stop, deviate or slow down the flow. Because of the complexity of the landslide-barrier interaction, the design of these defence structures is still based on oversimplified and empirical approaches. Numerical methods able to cap-ture the essential features of the phenomenon can offer a valuable tool to gain a better understanding of the impact process and to support the design. This paper shows the potentialities of the MPM in this field. The run-up of the landslide and the dynamic forces on the structure are some of the fundamental parameters to define the properties of the barrier

Distributed optical fibre sensing for early detection of shallow landslides triggering

A distributed optical fibre sensing system is used to measure landslide-induced strains on an optical fibre buried in a\uc2\ua0large scale physical model of a slope. The fibre sensing cable is deployed at the predefined failure surface and interrogated by means of optical frequency domain reflectometry. The strain evolution is measured with centimetre spatial resolution until the occurrence of the slope failure. Standard legacy sensors measuring soil moisture and pore water pressure are installed at different depths and positions along the slope for comparison and validation. The evolution of the strain field is related to landslide dynamics with unprecedented resolution and insight. In fact, the results of the experiment clearly identify several phases within the evolution of the landslide and show that optical fibres can detect precursory signs of failure well before the collapse, paving the way for the development of more effective early warning systems

Alteration of Fecal Microbiota Profiles in Juvenile Idiopathic Arthritis. Associations with HLA-B27 Allele and Disease Status.

Alteration of gut microbiota is involved in several chronic inflammatory and autoimmune diseases, including rheumatoid arthritis, and gut microbial pro-arthritogenic profiles have been hypothesized. Intestinal inflammation may be involved in spondyloarthropathies and in a subset of patients affected by Juvenile Idiopathic Arthritis (JIA), the most common chronic rheumatic disease of childhood. We compared the fecal microbiota composition of JIA patients with healthy subjects (HS), evaluating differences in microbial profiles between sub-categories of JIA, such as enthesitis-related arthritis (JIA-ERA), in which inflammation of entheses occurs, and polyarticular JIA, non-enthesitis related arthritis (JIA-nERA). Through taxon-level analysis, we discovered alteration of fecal microbiota components that could be involved in subclinical gut inflammation, and promotion of joint inflammation. We observed abundance in Ruminococcaceae in both JIA categories, reduction in Clostridiaceae and Peptostreptococcaceae in JIA-ERA, and increase in Veillonellaceae in JIA-nERA, respectively compared with HS. Among the more relevant genera, we found an increase in Clostridium cluster XIVb, involved in colitis and arthritis, in JIA-ERA patients compared with HS, and a trend of decrease in Faecalibacterium, known for anti-inflammatory properties, in JIA-nERA compared with JIA-ERA and HS. Differential abundant taxa identified JIA patients for the HLA-B27 allele, including Bilophila, Clostridium cluster XIVb, Oscillibacter and Parvimonas. Prediction analysis of metabolic functions showed that JIA-ERA metagenome was differentially enriched in bacterial functions related to cell motility and chemotaxis, suggesting selection of potential virulence traits. We also discovered differential microbial profiles and intra-group variability among active disease and remission, suggesting instability of microbial ecosystem in autoimmune diseases with respect to healthy status. Similarly to other chronic autoimmune and inflammatory diseases, different microbial profiles, as observed among different JIA subgroups compared to HS, and potential functional acquisition related to migration could promote inflammation and contribute to the disease pathogenesis

Experiences and Lessons Learned from the SIGMOD Entity Resolution Programming Contests

We report our experience in running three editions (2020, 2021, 2022) of the SIGMOD programming contest, a well-known event for students to engage in solving exciting data management problems. During this period we had the opportunity of introducing participants to the entity resolution task, which is of paramount importance in the data integration community. We aim at sharing the executive decisions, made by the people co-authoring this report, and the lessons learned