Selection of Standard Penetration Test Number for Geotechnical Investigation of a Vertical Cross-section Considering Spatial Variability and Correlation in Soil Properties

Standard Penetration test (SPT) is a widely used in-situ test for characterizing variation of subsurface soil properties, and results of site investigation are usually simplified as a 2D vertical cross-section for subsequent geotechnical design and construction. Current geotechnical design codes and guidelines only provide general recommendations for selection of an appropriate number of in-situ tests (e.g., SPT) (e.g., the greater variability of subsurface conditions, the larger number of SPTs required to obtain sufficient underground information). No quantitative or rational method is available for selecting the appropriate number of SPTs considering spatial variability and correlation in subsurface conditions. A comprehensive parametric study is carried out in this study to investigate the influence of spatial variability in subsurface conditions on the minimum SPT number needed for satisfying an accuracy requirement of site investigation. Random field is adopted to model spatial variation and correlation in soil properties in typical site conditions, and 2D Bayesian compressive sampling is used to interpolate sparse SPT data. Based on the parametric study results, a statistical chart is developed for geotechnical engineers to conveniently select appropriate number of SPTs in a vertical cross-section. Real SPT data from New Zealand are used to illustrate and validate the proposed method.

Cone penetration test (CPT)-based subsurface soil classification and zonation in two-dimensional vertical cross section using Bayesian compressive sampling

A novel method is developed in this study for soil classification and zonation in a two-dimensional (2D) vertical cross section using cone penetration tests (CPTs). A CPT is usually performed vertically and the number of CPT soundings in a site is often limited in geotechnical engineering practice. It is, therefore, difficult to properly interpret CPT results along the horizontal direction or accurately estimate the horizontal correlation length of CPT data. The method proposed in this study bypasses the difficulty in estimating horizontal correlation length and provides proper identification of subsurface soil stratification (i.e., soil layer number is constant along horizontal direction) and zonation (i.e., soil layer number varies along horizontal direction) in a 2D vertical cross section directly from a limited number of CPT soundings. The proposed method consists of three key elements: 2D interpolation of CPT data using 2D Bayesian compressive sampling; determination of soil behavior type (SBT) using a SBT chart at every location in the 2D section, including locations with measurements and unsampled locations; and soil layer or zone delineation using an edge detection method. Both simulated and real data examples are used to illustrate the proposed method. Results show that the method performs well even when only five sets of CPT soundings are available.

Численное моделирование процесса получения мультикремния методом направленной кристаллизации

Numerical simulation of silicon multi-crystal growth by directional solidification with a square crucible is considered. We validate the use of 2D geometry of the vertical cross section as a computational domain. The model describes melt hydrodynamics, global heat transfer, thermal stresses and the evolution of the dislocation density in the crystal. The sensitivity of the stresses and dislocation density in the Si crystal to the parameters of the Alexander-Haazen model is analyzed.

Radar-Based Automatic Identification and Quantification of Weak Echo Regions for Hail Nowcasting

The identification of some radar reflectivity signatures plays a vital role in severe thunderstorm nowcasting. A weak echo region is one of the signatures that could indicate updraft, which is a fundamental condition for hail production. However, this signature is underutilized in automatic forecasting systems due to the lack of a reliable detection method and the uncertain relationships between different weak echo regions and hail-producing thunderstorms. In this paper, three algorithms related to weak echo regions are proposed. The first is a quasi-real-time weak echo region morphology identification algorithm using the radar echo bottom height image. The second is an automatic vertical cross-section-making algorithm. It provides a convenient tool for automatically determining the location of a vertical cross-section that exhibits a visible weak echo region to help forecasters assess the vertical structures of thunderstorms with less time consumption. The last is a weak echo region quantification algorithm mainly used for hail nowcasting. It could generate a parameter describing the scale of a weak echo region to distinguish hail and no-hail thunderstorms. Evaluation with real data of the Tianjin radar indicates that the critical success index of the weak echo region identification algorithm is 0.61. Statistics on these data also show that when the weak echo region parameters generated by the quantification algorithm are in a particular range, more than 85% of the convective cells produced hail.

BIM Capability Audit of Contracting-Based Organisations

The UK government set up a BIM Task Group in 2011 to provide guidance and support to the industry. This paper reports on BIM Capability audits that were undertaken on two contractor-based organisations to assess their level of readiness to implement BIM level 2 and to highlight training and upskilling needs. The audits were undertaken using a detailed set of 80 questions covering technology, workflows, processes and business strategies. Follow up interviews were undertaken to clarify any ambiguities in the responses received. A vertical cross section of each organisation was audited in order to provide a fully representative sample of the companies as the implementation of BIM will have an impact on the whole business model of the firms. The organisations had differing aspirations and timescales for the implementation of BIM and to some extent this was demonstrated by the outcome of the audits. The results were found to be consistent with the findings of another major similar HS2 upskilling study which the authors were also involved in.

3D Modeling of Underground Geological Park Based on Terrestrial Laser Scanner

The main idea of this paper is to describe the application of Terrestrial Laser Scanner in 3D modeling. Considering the special terrain structure of underground geological park, a 3D modeling procedure based on Terrestrial Laser Scanner is designed. The graphs of vertical cross-section and horizontal cross-section are achieved after model optimization. Experiments show that the method can work better than Ground-based measurements in 3D modeling of underground geological park. The 3D model of underground geological park can be used to monitor the amount of mining and get the graphs of vertical cross-section and horizontal cross-section, which will be applied widely in future.