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This project documents flood-induced geo-structural damage and geomorphological change due to the flooding in the Ahr Valley in Germany during the 2021 Western European floods. It contains detailed, multi-instrument measurements both within the river channel and along the river banks at five carefully selected sites. 

Embedded sensors within infrastructure elements are powerful catalysts for new designs and construction methods, enabling advanced data collection and informed decision making. This paper presents the development, validation, and implementation of a prototype instrumentation tool utilized in large-scale lateral load tests of rock-socketed pile foundations, with the objective to measure shear stresses near the rock-soil boundary. The proposed instrumentation is novel in that it will be the first attempt to determine experimentally the 3D strain field through embedded sensors with immediate application to a broad array of pile foundation engineering problems. Data obtained from the prototype instrumentation is used to clarify whether shear force amplifications in piles crossing soils with strong stiffness contrasts are real, or an artifact of analytical, Winkler-based design methodologies. Three reinforced concrete pile specimens with a diameter of 0.46 m and a length of 4.9 m were subjected to reverse cyclic lateral loading up to complete structural failure. The sensors’ development, design, and construction, as well as their performance in measuring shear stresses will be discussed by comparing experimental data with predictions from conventional software tools. Ultimately, this study aims to improve the design and construction of more practical, resilient, and economical infrastructure. 

Between July 14–16th, 2021, record rainfall and subsequent flooding resulted in the deaths of over 200 people and billions of dollars-worth of damage in Germany and Belgium. An NSF sponsored Geotechnical Extreme Events Reconnaissance (GEER) Association reconnaissance mission was undertaken by the authors to investigate the effects of flooding in Germany, Belgium, and the Netherlands. The two-week-long mission provided insight to the performance of various geostructures such as building foundations, roads, and bridges. This paper provides a summary of observations made by the US-based GEER team in collaboration with many local European colleagues. Key observations presented include a bridge case study, the impact of scour and erosion on different structures, and soil-structure interactions. A review of the data used to inform the reconnaissance mission as well as the data collection technologies used, including terrestrial LiDAR, UAV-Structure from Motion (SfM), and multispectral imagery, is also presented. 

The Los Angeles (LA) Metro Purple Line (D-Line) Extension project requires the design and construction of deep station excavations and tunnels for rail transit from downtown to west LA. The tunnel alignment for Reach 2 of the Westside Purple Line Extension 1 construction transects naturally-occurring tar-infused soils, which have been known to cause challenging construction conditions in southern California, as well as many other locations around the world. Two stations in similar geology but located within and outside tar soils were compared. The soil investigations of the tunnels and station excavations consisted of subsurface exploration including deep soil borings, Cone Penetration Testing (CPT), seismic velocity measurements, pressuremeter testing, and gas measurements, among others. The results of CPT and shear-wave velocity testing provide extensive data in tar soils unique to Southern California and an opportunity to increase our understanding of four-phase soil materials and the effects of tar on soil behavior interpretation and engineering properties. CPT correlations for conventional (non-tar-infused) soils were found to be inadequate for tar soils in the Los Angeles basin. The CPT based Soil Behavior Type Index (SBTn) determined in tar soils suggested the presence of much finer-grained material than determined from laboratory testing and field observations. Additionally, the presence of tar soils amplified the difference between CPT correlations for shear wave velocity (Vs) and direct Vs seismic CPT measurements. 

In June 2022, the southern part of Montana and the northern part of Yellowstone National Park experienced flooding along multiple watersheds, including the Yellowstone River. The flooding resulted from heavy snowmelt between June 10-13th, leading to record levels of river water elevation in most of the main tributaries to the Yellowstone River. Substantial damage occurred to residential, commercial, and transport infrastructure, however, no fatalities were reported. Estimated damages accumulate to approximately U.S. $29 million. The GEER reconnaissance effort, conducted between June 30th – July 4th, recorded geotechnical, geo-structural, and geomorphological observations of failures as well as successful mitigation of flood damage. In addition to traditional terrestrial photography and aerial imagery, the team collected (Light Detection Ranging (LIDAR) scanning, Structure for Motion (SfM) imagery, and Multispectral Imagery to establish point cloud models for case history analyses and post-reconnaissance failure analyses. 

Estimating excavation-induced ground surface displacements in urban areas is needed to assess potential structure damage. Empirical settlement distribution models have been widely used to estimate the zone of influence and ground response behind braced excavation walls. Three underground station excavations, part of the Los Angeles Metro’s K Line Crenshaw/LAX Transit Project, offer a unique opportunity to collect field instrumentation data to improve estimates of ground deformations. One excavation employed cross-lot braces and soldier piles and wood lagging while the other two were supported by cross-lot braces and stiffer Cutter-Soil-Mixing (CSM) walls. For the excavations with stiff support systems and relatively small wall movements, upward surface displacement or heave governed the ground surface response, while surface settlement was measured at the excavation with the more flexible wall system. This heave behavior is often masked by settlement caused by relatively large wall movements, and is thus commonly disregarded. By idealizing the excavation unloading as an upward strip load at the ground surface, the Boussinesq solution for elastic upward movement can be used in combination with a settlement component resulting from lateral wall movements to estimate the magnitude and distribution of excavation-induced surface displacements.