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This paper presents an implementation of the c-phi reduction procedure in the finite element code Cast3M. This procedure is first validated on a simple example of bearing capacity of a strip footing and then used to evaluate the stability factor of a geotechnical structure composed of two levels of backfill retained by two retaining walls, with a road built on the top of the second backfill. The results of the c-phi reduction procedure for the construction of first and second backfill are also compared to other analysis methods classically used in geotechnics and to the results of finite element calculations.

Surface monitoring of landfills is crucial not only during their operation but also for later land restoration and development. Measurements concern environmental factors, such as leachate, migration of pollutants to water, biogas, and atmospheric emissions, and geotechnical factors, such as stability and subsidence. Landfill subsidence can be measured using modern surveying techniques. Modern measurement methods for landfill body displacement monitoring and their control after restoration and adaptation as recreational areas include terrestrial laser scanning (TLS), and scanning and low-altitude photogrammetric measurements from an unmanned aerial vehicle (UAV). The acquired measurement data in the form of 3D point clouds should be referenced to the local control network to enable a comprehensive analysis of data acquired using various techniques, including geotechnical sensors such as benchmarks, piezometers, and inclinometers. This study discusses the need for surface monitoring of municipal solid waste (MSW) landfills. A properly 3-D mapped landfill mass is the basis for ensuring the geotechnical safety of the restored landfill. Based on archival data and current measurements of the Radiowo landfill (Poland), this study compares the advantages and limitations of the following measurement techniques: linear and angular measurements, satellite measurements, TLS, and UAV scanning and photogrammetry, considering specific conditions of the location and vegetation of the landfill. Solutions for long-term monitoring were proposed, considering the cost and time resolution necessary for creating a differential model of landfill geometry changes. [ABSTRACT FROM AUTHOR]

Geotechnical engineering is characterized by many uncertainties, including soil material properties, environmental effects, and engineering design and construction, which bring a significant challenge to geotechnical monitoring. However, conventional sensors with several inherent limitations, such as electromagnetic interference, signal loss in long-distance transmission, and low durability in harsh environments cannot fully meet current monitoring needs. Recently, fiber optic sensing technologies have been successfully applied in geotechnical monitoring due to the significant advantages of anti-electromagnetic interference, stable signal long-distance transmission, high durability, high sensitivity, and lightweight, which can be considered an ideal replacement for conventional sensors. In this paper, the working principle of different fiber optic sensing technologies, the development of fiber optic-based sensors, and the recent application status of these sensing technologies for geotechnical monitoring were comprehensively reviewed and discussed in detail. Finally, the challenges and countermeasures of the sensing technologies in geotechnical monitoring were also presented and discussed. [ABSTRACT FROM AUTHOR]

Geodetic monitoring of deformation has an important role in ensuring the safety of geotechnical objects by monitoring of not exceeding the critical states defined for slope stability and monitoring the uniformity of the object settlement process. A special case of such objects are landfills built of various anthropogenic materials. Heterogeneous building material causes increased values of displacements in relation to other geotechnical objects and requires that measurement works be carried out throughout the entire life cycle of the landfill: both in the exploitation phase, during the reclamation period and in the post-exploitation phase. This study presents the methodology of geodetic measurements of deformation of geotechnical objects on the example of the Radiowo landfill and the results of this type of measurements carried out for 30 years on this object. The analysis of the literature has also shown that, in addition to the commonly used geodetic methods, it is possible to use modern measurement methods such as laser scanning and photogrammetry, which are more and more often successfully used in the measurement of this type of structures. These methods can be an interesting alternative in measuring the displacement of landfills or constitute their perfect supplement. [ABSTRACT FROM AUTHOR]

Production engineering methods and geotechnical instrumentation for the construction and reconstruction of railway beds in high temperatures in the Arctic zone are proposed. High-technology construction facilitates the development of transport infrastructure of the energy-producing industries in the Arctic. The example of the Northern Latitudinal Railway (NLR) highlights the probability of dangerous cryogenic processes and phenomena during works, such as waterlogging and the structural decline of the active soil layer, the development of taliks, and frost cracking, which lead to a decrease in bearing capacity of soil. The features of the construction and production plans used at the sites of railway embankment reconstruction with heavy-duty equipment are outlined. New process control methods have been developed based on the selection of and systematic changes in the parameters of maximum permissible construction loads depending on the results of geotechnical structure monitoring. The structural diagram of high technology for strengthening the weak subgrade soil under the conditions of talik development is substantiated. In order to regulate intensive process parameters, the vehicle fleet needs to be equipped with positioning devices and automation process control systems. The effectiveness of process control in terms of improving the reliability and accelerating roadbed consolidation is substantiated. [ABSTRACT FROM AUTHOR]

This work aims to study the influence of different geological and rock-soil structures on the bearing capacity of an underground continuous wall base. With an experimental area as the example, the geomorphology, rock mass, hydrology, and physical characteristics of the area are measured. The new geotechnical structure and wall base measurement experiments are conducted, and triaxial tests are carried out under varying temperature conditions, to study the influence of confining pressure and temperature on the deformation characteristics of the sample, as well as the influence of temperature on the strength characteristics of the sample. The results show that under the same temperature load, as the surrounding pressure increases from 100 to 400 kPa, the failure stress of the sample is gradually increasing when it reaches the failure strain. The shear strength of geological soft clay has a strong dependence on temperature. In the test range, as the temperature increases, the cohesive force c of soft clay decreases, and the value of the internal friction angle φ increases. The side friction resistance of the soft soil layer increased significantly after heating compared with that before heating. After standing for 112 days, the side friction resistance of 0–13.1 m remains unchanged, and the side friction resistance of the hard soil layer of 13.1–19 m increases, with an increase in the range of 20–28%. This work analyzes the influence of different geological and rock-soil structures on the bearing capacity of the continuous wall base and clarifies the important role played by geological rock and soil temperature, which provides a certain theoretical foundation and practical experience for the construction of the underground continuous wall base. [ABSTRACT FROM AUTHOR]

Production engineering methods and geotechnical instrumentation for the construction and reconstruction of railway beds in high temperatures in the Arctic zone are proposed. High-technology construction facilitates the development of transport infrastructure of the energy-producing industries in the Arctic. The example of the Northern Latitudinal Railway (NLR) highlights the probability of dangerous cryogenic processes and phenomena during works, such as waterlogging and the structural decline of the active soil layer, the development of taliks, and frost cracking, which lead to a decrease in bearing capacity of soil. The features of the construction and production plans used at the sites of railway embankment reconstruction with heavy-duty equipment are outlined. New process control methods have been developed based on the selection of and systematic changes in the parameters of maximum permissible construction loads depending on the results of geotechnical structure monitoring. The structural diagram of high technology for strengthening the weak subgrade soil under the conditions of talik development is substantiated. In order to regulate intensive process parameters, the vehicle fleet needs to be equipped with positioning devices and automation process control systems. The effectiveness of process control in terms of improving the reliability and accelerating roadbed consolidation is substantiated.

In stability reliability analysis of complicated geotechnical structure, the analytical expression of limit state function (LSF) is often highly non-linear, implicit or indefinable. This results in the classical second-order reliability method (SORM) not to be applied directly. The present study is devoted to eliminating this dilemma. Firstly, universal solving methods of partial derivatives of LSF to its basic random variables are derived using finite difference principle. Secondly, the universal methods supplement SORM to substitute for Newton–Leibniz derivation method; then, an improved algorithm of SORM is developed in conjunction with Breitung's notion. Thirdly, reliability evaluation of three examples with explicit/implicit LSF are carried out, an available constant quantity of step length coefficient is sought out in the independent standard normal space (u-space) through theoretical inference and trial. Fourthly, an extensive SORM (ESORM) that does not resort to any abstruse mathematic theories is further formulated. Fifthly, combined with numerical simulation, stability reliability degree of one excavation, of which LSF is indefinable, is analysed immediately. Therefore, a practical alternative approach of SORM for complicated geotechnical structure is constructed in the present study. [ABSTRACT FROM AUTHOR]

With the increased global interest in greenhouse gas reduction, many countries around the world have been making a range of efforts to reduce greenhouse gas emissions. The Ministry of Environment suggested a goal of 37% reduction relative to the expected greenhouse gas 'business as usual' (BAU) for all industries; thus, greenhouse gas reduction in the construction industry is also inevitable. To reduce greenhouse gas, the effects of a construction project on the environment need to be minimized, and an integrated evaluation that involves various kinds of environmental pollution (e.g., resource usage, water, air, and soil) as well as greenhouse gas is required. Therefore, in this study, for a reasonable and objectively valid evaluation of the environment-friendliness of a tunnel facility (a geotechnical structure), a life cycle assessment was performed based on existing cases following the ISO 14040 series standard. The purpose of this study is to suggest an environmental load evaluation technique that statistically analyzes the effects of work processes, input materials, and energy sources during tunnel work by suggesting the estimation equation for 8 impact categories that affect environmental load. [ABSTRACT FROM AUTHOR]

In recent decades, conventional electric instruments have already been widely used to monitor the performance of geotechnical structures. However, there are several inherent limitations of electric instruments for engineering including: electromagnetic interference, a large number of cables for multipoint measurement, signal loss in long distance transmission, and poor durability. Since the first Fiber Bragg Grating (FBG) sensor was fabricated in 1978, a significant progress has been made on the commercialization of optical fiber sensing technologies. In 1980s, a fully distributed sensing technology named Brillouin Optical Time Domain Analysis (BOTDA) has been proposed and developed for measuring strain and temperature. In this paper, the authors review previous studies on the development and application of fiber optic sensors. Based on the measured strains, various analysis methods were transferred to required parameters such as displacement, force and pressure which can more directly reflect the safety of geotechnical structures under complex engineering stress condition. [ABSTRACT FROM AUTHOR]

This study aims to address how efforts spent in geotechnical site investigation can link to the final design dimensions of a geotechnical structure. An example of pad foundation design supported by boulder clay (developed by European Technical Committee 10) is used as a demonstration. Three aspects of geotechnical information are addressed: variety of in-situ and laboratory tests, precision of the tests, and local experiences in soil properties that permit reduction of transformation uncertainties between test indices and design parameters. Three design methods (allowable stress design ASD, partial-factor design PFD, and reliability-based design RBD) are considered. Among these methods, RBD is found to be most responsive to the availability of geotechnical information, whether in the form of site investigation efforts and/or local experiences. It is accurate to say that RBD can fill a critical gap in current geotechnical design practice, namely to monetize the value of geotechnical information in the form of increase/reduction of construction costs associated with changes in the design dimensions. [ABSTRACT FROM AUTHOR]