Actual Ground Conditions Research Articles

Seismic Wave Amplification Characteristics in Slope Sections of Various Inclined Model Grounds

The collapse of slopes caused by earthquakes can lead to landslides, resulting in significant damage to both lives and structures. Seismic reinforcement of these slopes can protect social systems during an earthquake. In South Korea, where more than 70% of the land is mountainous, the stability of slopes is of paramount importance compared to other countries. While many seismic designs are based on peak ground acceleration (PGA), there is relatively little consideration given to the extent of PGA’s influence, and few studies have been done. This study aims to assess the seismic amplification of slopes with multilayers using a 1 g shaking table and verify the results through numerical analysis after confirming the impact of PGA at specific points. Typically, slope model experiments are conducted on single-layered ground models. However, actual ground conditions consist of multiple layers rather than a single layer, so a multi-layered model was created with different properties for the upper and lower layers. Two multi-layered ground models consisting of two layers were created, one with a flat ground surface and the other with a sloped surface. The properties of the two layers in each model were configured as a single layer to create the slope models. The peak ground acceleration (PGA) of the four ground models was compared, revealing that seismic wave amplification increases as it moves upward, and the amplification is even greater when transitioning from the lower to the upper ground layers, leading to different dynamic behavior of the slope. Through the contour lines, the influence of PGA was further confirmed, and it was found that approximately 60% of the PGA impact occurs at the topmost part of the slope on average. Analysis of the earthquake waves showed that the top of the slope experienced an average amplification of about 31.75% compared to the input motion, while the lower part experienced an average amplification of about 27.85%. Numerical analysis was performed using the ABAQUS program, and the results were compared with the 1 g shaking table experiments through spectral acceleration (SA), showing good agreement with the experimental results.

Predicting the geological condition beyond the tunnel excavation face using MSP monitoring data and LSTM algorithm

The ground conditions beyond an excavation face, especially discontinuities in rock masses, have a significant influence on tunnel construction. However, the actual ground conditions observed during tunnel construction are often different from the ground conditions predicted in the geotechnical site explorations carried out in the design stage. Changes in ground conditions may require alterations in tunnel design, leading to substantial disruptions in the construction schedule and budget. In this regard, accurate ground evaluation prior to the design and construction stages are essential for successful tunnel construction projects. Machine learning models have been developed in order to evaluate the condition of rock discontinuities within 50 m of the tunnel face. Machine data (rotational pressure, feed pressure, and drilling (advance) speed) obtained from a large boring hole machine, called MSP, at an NATM construction site in a granite formation located in South Korea were logged, and the actual ground Discontinuity Score (DS) was appraised by analysing internal bore hole images taken after drilling. Then, the LSTM algorithm was applied to develop the machine learning model to determine DS based on the logged machine data. DS was most accurately predicted when the drilling speed was included in the input data, whereas those cases using only the rotational and feed pressure in the input data showed low prediction accuracy. Therefore, the drilling speed seems to have a higher correlation than hydraulic pressure with regard to ground conditions, including discontinuities. Once additional data is collected from various tunnel sites, the machine learning model could be further enhanced to become more robust and provide solutions to various engineering problems.

An approach to estimate influence region of field investigation sampling points, investigation zone in civil infrastructure projects and brief review of existing field investigation process

Geotechnical investigation is a cyclic process. The interdependency between different steps involved in whole process, i.e., from planning, performing investigation, transporting samples and analysis of data obtained from field or lab, present opportunities for improvements and further discussion.For estimating number of investigation sampling points required for a particular site and selection of investigation methods, today we mostly relay on information from previously conducted site investigations, local experience from that area or site. In geotechnical investigation getting field samples which represents actual ground conditions for the whole site is well known challenge and has been highlighted in many research papers.In this paper we are presenting concept of influence region of geotechnical investigation points and an approach for estimation of the same. We believe the influence region concept; its estimation approach will provide a mathematical model and will help in deciding number of sampling points at the geotechnical investigation sites. In author’s opinion the presented concept will further improve the quality of geotechnical ground investigation process and will provide help in getting representative, quality field samples for laboratory analysis.The presented concept and estimation approach in this paper is based on author’s field experience and exposure gained from working in Swedish infrastructure projects. We think the influence region concept will further improve the existing geotechnical ground investigation process and will open opportunities for its validation through focused scientific research.A brief overview of the existing ground investigation processes has been covered in the paper, along with examples from geotechnical site investigations from Trafikverket (The Swedish Transport Administration) projects in Sweden.

Importance of Calibration for Improving the Efficiency of Data Assimilation for Predicting Forest Characteristics

Data assimilation (DA) is often used for merging observations to improve the predictions of the current and future states of characteristics of interest. In forest inventory, DA has so far found limited use, although dense time series of remotely sensed (RS) data have become available for estimating forest characteristics. A problem in forest inventory applications based on RS data is that errors from subsequent predictions tend to be strongly correlated, which limits the efficiency of DA. One reason for such a correlation is that model-based predictions, using techniques such as parametric or non-parametric regression, are normally biased conditional on the actual ground conditions, although they are unbiased conditional on the RS predictor variables. A typical case is that predictions are shifted towards the mean, i.e., small true values are overestimated, and large true values are underestimated. In this study, we evaluated if the classical calibration of RS-based predictions could remove this type of bias and improve DA results. Through a simulation study, we mimicked growing stock volume predictions from two different sensors: one from a metric strongly correlated with growing stock volume, mimicking airborne laser scanning, and one from a metric slightly less correlated with growing stock volume, mimicking data obtained from 3D digital photogrammetry. Consistent with previous findings, in areas such as chemistry, we found that classical calibration made the predictions approximately unbiased. Further, in most cases, calibration improved the DA results, evaluated in terms of the root mean square error of predicted volumes, evaluated at the end of a series of ten RS-based predictions.

Geotechnical Challenges And Lessons Learnt From Bolivia Hill Upgrade Project

This paper presents a case study of geotechnical design and construction challenges of bridge foundations and approaches in a hilly granite formation in northern New South Wales, Australia. Firstly, the geological formation and existing cut slope conditions which have high risks of rock fall is described. The detailed design was based on the available geotechnical information and assumed construction methodology. Reinforced concrete cantilever retaining walls founded on mass concrete were adopted for the bridge southern approach to resolve constructability issues over hilly terrain. Slope treatments using a rock fall fence together with individual boulder stabilisation or removal were also considered. It was found during construction that the actual ground conditions were different to that originally inferred and modifications to pad footing designs were deemed necessary. Additional investigations were undertaken, and the subsurface ground models updated to inform the revised design. For the northern bridge abutment foundation, a piled foundation was introduced to optimise the design with due consideration of temporary piling platform and access along a new geotextile reinforced approach embankment. The revised design was developed in close collaboration with the Contractor and the Principal. The foundation design of Pier 2 was revised using micro-piles to address the presence of a weak rock layer intrusion. In the end, key lessons learnt from this challenging project have been summarised for future project references.

Distributed Fibre Optic Sensing (DFOS) for Deformation Assessment of Composite Collectors and Pipelines.

Due to the low costs of distributed optical fibre sensors (DFOS) and the possibility of their direct integration within layered composite members, DFOS technology has considerable potential in structural health monitoring of linear underground infrastructures. Often, it is challenging to truly simulate the actual ground conditions at all construction stages. Thus, reliable measurements are required to adjust the model and verify theoretical calculations. The article presents a new approach to monitor displacements and strains in Glass Fiber Reinforced Polymer (GFRP) collectors and pipelines using DFOS. The research verifies the effectiveness of the proposed monitoring solution for health monitoring of composite pipelines. Optical fibres were installed over the circumference of a composite tubular pipe, both on the internal and external surfaces, while loaded externally. Analysis of strain profiles allowed for calculating the actual displacements (shape) of the pipe within its cross-section plane using the Trapezoidal method. The accuracy of proposed approach was positively verified both with reference spot displacement transducer as well as numerical simulations using finite element method (FEM). DFOS could obtain a comprehensive view of structural deformations, including both strains and displacements under externally applied load. The knowledge gained during research will be ultimately used for renovating existing collectors.

Rock joint scale effects in numerical modelling - Hinkley Point C, a case study

This paper presents the details of the approach to numerical modelling of the subvertical rock slopes resulting from the deep excavations associated with the foundations and basements for Hinkley Point C, Nuclear Power Station, in Somerset, UK. The ground model, which was based on an extensive ground investigation, indicated that the rock mass comprised thinly bedded mudstones and occasional limestones of the Blue Lias Formation. The structural geology of the site consisted of two major faults with five minor faults. These faulting resulted in highly fractured rocks with closely spaced discontinuities with unfavourable orientations and dip angles relative to the slope face. The design methodology for the project included Discrete Element Method (DEM) of numerical modelling using UDEC, a commercial software suitable for modelling fractured rock behaviour. As part of the development of the analytical model, a number of simplifications in terms of modelling, needed to be undertaken to enable development of a series of models that adequately reflected the likely ground conditions during excavation, but that could be run effectively under the usual constraints of a commercial project. One of such key simplifications relates to rock joint spacings. Modelling the rock joints spacings as measured on site in UDEC would result in extremely long computation time. It was necessary to scale up joint spacing in the model without compromising on the accuracy of the results. Series of sensitivity analyses were carried out to assess the effects of joint spacing on the slope stability analysis. From these analyses, an appropriate joint spacing scale up factor was derived. The output from the modelling included assessments of likely displacement of the rock slopes during excavation and as part of the construction works for the basements a programme of extensive monitoring was undertaken to verify the results of the modelling. The paper presents the ground model as interpreted from the ground investigation, the sensitivity analysis undertaken to help develop the approach for the analytical model and the results of the numerical modelling. It then goes on to compare these with the actual ground conditions revealed as excavation was undertaken, and the deformation recorded on the rock slopes during excavation. The paper goes on to present conclusions with respect to the modelling similar rock masses effectively using numerical modelling techniques.

The Optimization Model of Composite Material UAV Shooting Flight Routes

UAV is one of the important achievements of scientific and technological innovation, which has been widely used in various fields of life in recent years. UAVs of composite materials are the most popular because the composite itself has designability, and can be optimized according to the strength and stiffness of the aircraft without changing the structural weight. In order to ensure the UAV to carry out more accurate image acquisition under the actual ground conditions, through the analysis of decision variables, this paper uses the linear weighting of image shooting range and pixel accuracy to establish the objective function, and establishes the optimal shooting angle under different constraints Considering the actual motion characteristics of objects such as automobiles, this paper assumes that the tracked ground targets are a class of motion objects with non-integrity constraints when the flight altitude of UAV is fixed and the flight speed is constant. The ground target model and the flight dynamics nonlinear model are established. This paper presents a new RRT* algorithm for path planning based on the obstacles encountered by UAV during flight, that is, using the cost function to select the node with the minimum cost in the field of expanding nodes as the parent node, using the MATLAB to select a reasonable obstacle avoidance strategy, the global optimal route is obtained by smoothing processing, and the data simulation test is carried out. The experimental results show that the model is robust.

Comparison of performance of single- and double-core prefabricated vertical drains for thick reclaimed ground improvement

The performance of a double-core prefabricated vertical drain (PVD), which could reduce the well resistance via its large cross-sectional area and structural stability, was investigated experimentally and numerically. The double-core and the conventional single-core PVD, which has been widely adopted in reclaimed ground improvement, were compared in this study. In the experimental investigation, modified Delft tests and a calibration chamber test were carried out in a laboratory to determine the discharge capacities of the PVDs. Thereafter, single- and double-core PVDs were installed in the Busan New Port site, which had a 40 m thickness of clay deposit, and the performances of the PVDs estimated through surface settlements were compared. In addition, a numerical program named ILLICON was applied with field measurements, and a parametric study was conducted for different discharge capacities of the PVDs. The result of the laboratory tests and field measurements indicated that there was no difference in the performance between the two types of PVDs for improving the soft ground, considering actual ground conditions. Similarly, the parametric study results also implied that both PVDs could be satisfactorily applied in thick reclaimed ground, and there is no significant difference in the performance of single- and double-core PVDs.

Landslide Susceptibility Modeling Using a Hybrid Bivariate Statistical and Expert Consultation Approach in Canada Hill, Sarawak, Malaysia

Landslide susceptibility assessment was conducted in Canada Hill, Sarawak, Malaysia through a combined bivariate statistics and expert consultation approach using geographical information system, which captures landslide-conditioning parameters specific to the study area; to ensure its usefulness in practice. Over the past four decades, many landslide parameters and increasingly sophisticated statistical methods have been used in landslide research. However, the findings have had very limited use in practice as the actual ground conditions are not well represented. The weakness is due to poor quality of data in landslide inventories and inadequate understanding of landslide-conditioning parameters. In this study, bivariate statistical method was used in conjunction with an iterative process of expert consultation. Thirteen original landslide-conditioning parameters were narrowed down to six, with the addition of a unique parameter, planar failure potential, which was selected based on expert input. The parameter captures planar failure landslides, which has the highest impact in the study area, causing loss of lives and property destruction. The inaugural landslide susceptibility map for the study area has five classes; very low, low, moderate, high and very high susceptibility. All major planar failures and most smaller circular failures fall within the very high susceptibility class, with a success rate of 75.8%. The approach used in this study has improved the quality of the landslide inventory and delineated key conditioning parameters. The resultant map captures local conditions, which is useful for landslide management.

Application of Artificial Neural Networks in Assessing Mining Subsidence Risk

Subsidence at abandoned mines sometimes causes destruction of local areas and casualties. This paper proposes a mine subsidence risk index and establishes a subsidence risk grade based on two separate analyses of A and B to predict the occurrence of subsidence at an abandoned mine. For the analyses, 227 locations were ultimately selected at 15 abandoned coal mines and 22 abandoned mines of other types (i.e., gold, silver, and metal mines). Analysis A predicts whether subsidence is likely using an artificial neural network. Analysis B assesses a mine subsidence risk index that indicates the extent of risk of subsidence. Results of both analyses are utilized to assign a subsidence risk grade to each ground location investigated. To check the model’s reliability, a new dataset of 22 locations was selected from five other abandoned mines; the subsidence risk grade results were compared with those of the actual ground conditions. The resulting correct prediction percentage for 13 subsidence locations of the abandoned mines was 83–86%. To improve reliability of the subsidence risk, much more subsidence data with greater variations in ground conditions is required, and various types of analyses by numerical and empirical approaches, etc. need to be combined.

Particle Crushing Effect on The Geotechnical Properties of Soil

Foundations are considered as the backbone of a structure. Most of the times, the foundation is laid on the soil. For the foundation design of any structure, we need to know beforehand the soil conditions such as shear strength and permeability. These parameters help us determine the bearing capacity of the soil. The soil conditions are determined by performing various laboratory tests such as shear box test or tri-axial shear test. However, we cannot design the foundation considering these data as the ground conditions will change once the loads are applied to the soil as there are some soil particles with angularity or sharp edges will break. Once they will break, soil conditions will not remain the same as they were before since the gradation will change. This work is carried out in order to know the impact soil breakage brings to the soil (granular soil). For this purpose, actual ground conditions were simulated in the laboratory by applying one-dimensional compression to soil particles for about 45 minutes in a Universal Testing Machine (UTM). Different crushing loads to soil particles were applied and the change in the soil behavior was monitored. It was found that due to particle breakage of soil, the engineering properties of sand altered. This research work aims to analyze the effect of particle breakage only in the case of sand.

Research on Hyperspectral Identification of Altered Minerals in Yemaquan West Gold Field, Xinjiang

Predictions of prospectivity based on remote sensing were developed using alteration mineral indicative hyperspectral mapping and remote sensing anomaly filtering, combined with geological characteristics and anomalous mineral field verification. Based on the results of the hyperspectral mineral mapping and the actual geological ground conditions, the results of mapping of altered minerals, such as chlorite, muscovite, kaolinite, and iron oxide were validated, and gold, silver, copper, nickel, and other geochemical anomaly areas were identified for verification work. The results of hyperspectral mineral extraction show that the mineral assemblage closely related to gold deposits in shear zones is muscovite + chlorite + epidote + kaolinite. This alteration mineral assemblage can be used as regional search criteria for shear zone gold mineralisation and was the basis for the discovery of mineralised hydrothermal alteration centres and delineation of four prospective targets. Established on a spectral prospectivity model of the study area, prospective ore-bearing areas have been delineated, which indicate the direction for further geological and mineral resource surveys.

Experience from TBM excavation obtained in the Follo Line Project

AbstractIn some projects the selection of TBM is straight forward, but in others all boundary conditions have to be carefully evaluated in order to make the most suitable choice. For underground projects the actual ground conditions remain to certain degree always unknown, regardless of the performed ground investigations. This means specific parameters, which may have significant impact on the project success, might be over‐ or underestimated. Such parameters could be different rock mass properties as well as water ingress. This paper discusses some relevant parameters for TBM selection in hard rock environment, mainly based on the experience gained in the Follo Line Project in Norway. Four double shield TBMs with excavation diameter of 9.96 m are drilling through various kinds of gneisses with banding and lenses of amphibolite and pegmatite. More than 75 % of a total of 36 km have already been excavated with several kilometres of pre‐excavation grouting for reduction of water ingress. Furthermore, potential improvements for TBMs will be proposed in order to make TBMs even more successful.

Mechanisms for preventing rising damp in new building infrastructure

PurposeCapillary rise of water in buildings has been an issue of concern among past and present researchers. Despite the research efforts devoted to the proper elimination of the problem in masonry construction, it still remains a challenge that needs to be addressed. The purpose of this paper is to explore treatment mechanisms that can be used to prevent rising damp in new building infrastructure.Design/methodology/approachIn total, 14 test walls are constructed, conditioned, subjected to various treatments and monitored for four years. The treatments applied to the walls include the use of polyethylene damp proof courses, damp proof coatings and dense concrete bases. The walls are then monitored with reference to the two climate seasons in Ghana.FindingsThe results highlight that rising damp is present, as suggested by the constant increase and decrease in the height of the water levels in the walls during the rainy and dry seasons, respectively. The findings further reveal that within the four-year period, the walls treated with the damp proof coatings, together with those with the dense concrete bases performed better than those treated with the polyethylene damp proof courses.Research limitations/implicationsThe economic and commercial impact of these preventive mechanisms were not considered in this study. A future research can be directed at these issues.Practical implicationsThe proposed treatment mechanisms highlight the effectiveness of some treatments applied to walls to prevent the capillary rise of water from the ground into the superstructure.Social implicationsBuilding regulations, especially in Ghana and other tropical settings should be amended to include ways to prevent rising damp phenomena by including effective methods against rising damp during the building design or construction.Originality/valueSeries of studies worldwide have been conducted in laboratories to simulate the capillary rise of water in walls of buildings. This is among the few studies that look at how water rises from actual ground conditions into the walls of buildings.

Determining the principles of tunnel support based on the engineering geological behaviour types: example of a tunnel in tectonically disturbed heterogeneous rock in Serbia

A methodology for designing a tunnel support system according to the actual ground conditions and the critical behaviour types is analysed in this paper. The methodology is justified with the principles of the New Austrian Tunnelling Method that incorporates the top heading and bench method. The role of the geological material and its implication in tunnel design, reinforced with advances in site investigation methods, cannot be based solely on the development of the geotechnical classification systems and the consequent quantification of the rock masses. Support requirements for rock masses with equal classification ratings can be different. The procedure presented in this study cannot bypass the geological and/or in situ characteristics dictating or influencing the tunnel behaviour compared with a standardised classification that could miss the specifics and particularities of and around a tunnel section. The step-by-step procedure is applied in a tunnel excavated in tectonically disturbed heterogeneous flysch sediments in Serbia. The complex structure of these materials, resulting from their depositional and tectonic history that includes severe faulting and folding, presents a challenge to geologists and engineers. The possible ground types are evaluated, and then, combined with the factors of the tunnel geometry, the primary stress condition, and the water conditions, several behaviour types are considered. These classified behaviour types, followed by the suitable mechanical properties that are required for effective tunnel engineering design, are the basis for the numerical design of the appropriate primary support measures to achieve stable tunnel conditions. The twin-tube, two-lane highway tunnel was successfully constructed without significant problems.

Analytical model for vacuum consolidation incorporating soil disturbance caused by mandrel-driven drains

When vacuum preloading is applied with vertical drains, the rate of consolidation can be increased, and the stability of an embankment is enhanced due to the inward lateral movement. The aim of this study is to develop an analytical solution for vacuum preloading that accurately captures the more realistic variations in compressibility and permeability in actual ground conditions as a result of drain installation. The soil samples were obtained from various locations after drain installation to determine the characteristics of soil surrounding the vertical drain in terms of compressibility and permeability. The main differences between the proposed and conventional models are described by considering the stress history and preloading pressure. The effect of pre-consolidation pressure and the magnitude of applied preloading are examined through the dissipation of average excess pore pressure and associated settlement. The analysis of a selected case history employing the writers’ solution indicates improved accuracy of the predictions in comparison to the field measurements.

Does adaptive strategy for delayed seed dispersion affect extinction probability of a desert species? an assessment using the population viability analysis and glass house experiment

Canopy seed bank is an important adaptive evolutionary trait that provides various types of protection to the seeds. However, costing of such evolutionary trait on plant survival is largely unknown. Present investigation provided a new insight on the serotonious habit of Blepharis sindica associated with its endangerment status. Extinction probabilities of two available population of B. sindica were quantified using two types of census data, i.e., fruiting body number and actual population size. Population Viability Analysis (PVA) revealed that delayed seed release tendency (higher fruiting body number) was not synchronized with actual ground conditions (lower population size). PVA analysis based on actual population size indicated that both the available populations would vanish within 20 years. The mean time of extinction calculated from both type census data indicated its extinction within 48 years. For assessing the conservation criteria, a glass house experiment was carried out with different soil types and compositions. Pure sand and higher proportions of sand -silt were more suitable compared to clay; further, gravelly surface was the most unsuitable habitat for this species. Collection of the seeds from mature fruits/capsule and their sowing with moderate moisture availability with sandy soil could be recommended.

A classification and survey system for forest cultural heritages in Korea

Worldwide, the conservation of cultural heritages plays an important role expressing cultural diversity. In Korea, conservative and historic forest-related tangible and intangible heritages are scattered across the nation but are not well managed. Research on actual ground conditions is needed to systematically excavate and conserve the forest cultural heritages. To give effective support to the survey, forest cultural heritages were divided systematically into different types based on qualitative research through solicitation of the expert opinions of seven specialists in four major fields. The survey criteria and targets were established for each type of forest cultural heritage. Based on their characteristics, each type of forest cultural heritage was classified into three sections, 16 divisions, and 68 classes. In order to reflect the characteristics of forest cultural heritages, the format for the survey field notes and the listing plan for the survey targets were also suggested.

The Relationship Between 2011 METAR and TAF Data at Chicago-Midway and Seattle-Tacoma Airports

This study examined the relationship between expected meteorological conditions as specified by TAF reports and actual ground conditions as specified by hourly METAR reports for Chicago-Midway (MDW) and Seattle-Tacoma (SEA) airports for the period September–December 2011. MDW and SEA were targeted because they had the highest and lowest percentage of delays, respectively, for 2011. The rationale was to determine if one of the contributing factors for the difference in percentage delays was because of the relationship between TAF and METAR reports. The primary hypothesis was that the relationship between the forecasts and actual ground conditions at MDW would be weaker than the corresponding relationship at SEA. TAF and METAR data were acquired from the respective TAF and METAR products pages at “Aviation Weather Charts Archive” (2012). Descriptive statistics revealed that MDW had less total departures than SEA (86,834 vs. 100,133) for all of 2011, but it also had nearly five times as many weather-related departure delays than SEA. Chi square analyses indicated that although the relationship between TAF and METAR at each airport was statistically significant, the corresponding Kappa agreement coefficients showed that this relationship was nearly twice as strong at MDW (.60) than at SEA (.35). Plausible explanations include that 70% of the weather conditions at MDW were VFR as opposed to only 56% at SEA, MDW had one-third the number of special METARS than SEA (374 vs. 917), and MDW had approximately one-fifth the number of LIFR conditions than SEA (70 vs. 337). The analysis also revealed that SEA had difficulty correctly forecasting IFR and LIFR conditions, especially under rapidly changing conditions. Based on the study’s findings, it appears that the relationship between TAF and METAR was not a contributing factor to departure delays at both MDW and SEA during the September– December 2011 period.