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.
•This paper offers a comprehensive review of using fiber optic sensing technologies for geotechnical monitoring.•This review aims at improving the acknowledgement of fiber optic sensing technologies for geotechnical monitoring.•Possible technical challenges are discussed, which can provide a reference for subsequent research.
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.
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.
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.
The first industrial trial of double-sided roof cutting with gob-side entry (N00 method) was used as the engineering background to study the effect of the roof cutting technique (RCT) in coal mining ...in terms of the extent of damage to the overlying geotechnical structure (OGS). A theoretical analysis model of the OGS was built for each method considered: the RCT (N00 method) results in more damage to the collapse zone than the traditional longwall mining method (121 method). Simulation models of these two methods were created in PFC
2D
to analyze the force chain distribution, fracture development, fragment evolution, and displacement variation patterns in the OGS. The RCT causes more collapse zone damage and less fracture zone damage and surface subsidence. The fracture zone damage contrast factor (
K
RFZ
) and the surface damage contrast factor (
K
SSZ
) were proposed as research indices. The greater the degree of damage weakening, the smaller
K
RFZ
and
K
SSZ
are. The average
K
RFZ
is 0.165, and the average
K
SSZ
is 0.845, indicating that in the OGS, damage weakening is greater in the fracture zone than at the surface. These results will provide new research ideas for the analysis of the OGS encountered in coal mining and can serve as references for similar geological and geotechnical research projects on the structural properties of strata.
BIM model represents a significant step forward within the frame of the overall process of construction. This new approach goes from the assumption that up to date praxis, which is represented by ...different sets of 2D or 3D drawings of drawings, technical reports and calculations does not cover all problems of the above mentioned overall process of construction. Basic principles of BIM will be discussed, not only from the view of 3D models of the structure design. The utilization of the BIM model during life time structure expectancy will be stressed - from the initial phase (investigation, design) via the phase of structure execution, maintenance and ending with structure demolition at the end of life time expectancy. Specificity of the geotechnical engineering is in this entire process fundamental, as each construction is in the interaction with ground. 3D model of the ground (geotechnical model) is therefore one of the basic individual parametric elements from which BIM model consist. Ground model is time dependant as geological profile and geotechnical properties are refinement during each phase of ground investigation as well during geotechnical structure construction. Final 3D Ground model together with 3D model of geotechnical structure represents a first significant step of the overall BIM model. In the case of underground or earth structures such output can be primordial element of the BIM model with parametric elements around it. Finally some other possibilities or practical applications are mentioned.
The rapid progress of digitalisation in civil engineering is also happening in the branch of geotechnical engineering. BIM is a part of this process. The mutual connection of a 3D model of ground ...with a 3D model of geotechnical structure can help to give a clearer view of the interaction of this structure and ground. At the same time it also makes possible better control for all participants in the construction process, particularly if all conditions of this mutual interaction are fulfilled. There is considered whether the main aim of the construction process, namely that the care devoted to the individual phases of the structure design and execution actually correspond to the risk with which this structure and ground are indeed connected. Within this context a closer specification of the Eurocode 7 of the second generation will be identified , especially as it relates to different models.
Due to the special internal and external dynamic action of the Qinghai-Tibet Plateau, the high and cold valleys are typically characterized by high-steep terrain, dry and cold climate, lithologic ...diversity, complex geological structure, and frequent occurrence of earthquakes. In this study, the types of special geotechnical structures of bank slope deposits in high and cold valleys are summarized based on field investigation, field and laboratory tests, and numerical simulation. These special deposits include colluvial-deluvial deposits, terrace deposits, early debris flow deposits, and landslide deposits. The formation mechanism, physical and mechanical properties, and stability analysis of these deposits were studied. The results show that the formation mechanism of various deposits is different, which is closely related to the intense geological tectonic action, the weathering and unloading action intensified by freezing and thawing cycles, and the special rock and soil structure in the high and cold valleys. Different material compositions have obvious effects on the physical and mechanical properties of the deposits, thus affecting the stability and deformation characteristics of the deposits. Under natural and saturated conditions, the stability of different types of the deposits is different, which is mainly related to the special geotechnical structure of various deposits. Compared with that before the reservoir impoundment, the stability factor of various deposits after the reservoir impoundment is significantly reduced. The performances can be provided as a reference for evaluating the stability of bank slope deposits in high and cold valleys.
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.
PDF
