Role In Geotechnical Engineering Research Articles

Optimization Of Cantilever Retaining Wall Design Using Improved Teaching-Learning-Based Optimization Algorithms

Retaining structures play a crucial role in geotechnical engineering to support soil levels, prevent slope failure, and create flat surfaces for construction. Designing these structures involves optimizing internal and external stability while minimizing material usage and cost. This study focused on optimizing reinforced concrete cantilever retaining walls using the Teaching-Learning Based Optimization (TLBO) algorithm and an improved version (I-TLBO) with agents. In the context of the study, geometric-structural design variables, geotechnical -structural constraints, and optimization processes were examined. Minimizing weight and minimizing cost of the wall were the objectives considered in the cantilever retaining wall design process. The optimization results were compared with other algorithms in the literature, such as genetic algorithms, evolutionary strategies, and particle swarm optimization. The improved TLBO algorithm demonstrated superior performance, achieved lower design dimensions, and reduced costs. It provided more efficient solutions that pushed design constraints closer to their limits, resulting in a cost-effective and structurally sound cantilever retaining wall design. As a result of the study, the I-TLBO algorithm was found to be more cost and weight-effective than other methods in the optimization of cantilever retaining wall design.

Experimental Investigation of the Soil-Water Characteristic Curves (SWCC) of Expansive Soil: Effects of Sand Content, Initial Saturation, and Initial Dry Unit Weight

Soil-water characteristic curve (SWCC) is an essential parameter in unsaturated soil mechanics, and it plays a significant role in geotechnical engineering to enhance theoretical analysis and numerical calculations. This study investigated the effects of key factors, such as the percentage of sand, initial degree of saturation, and initial dry unit weight, on the SWCC of expansive soil by measuring the matric suction using a pressure apparatus method. The empirical equation of SWCC was obtained using the Van Genuchten and Fredlung Xing models, and the processing of experimental data checks the fitting of the two empirical models. The findings revealed that the Fredlung Xing model fit the relationship between matric suction and volumetric water content of expansive soil better than the Van Genuchten model, indicating that the pressure apparatus approach’s experimental data are correct and acceptable. The study also found that the matric suction increased with decreasing percentage of added sand at the same volumetric moisture content, and the increase in initial dry unit weight increased the matric suction, with the water retention capacity decreasing significantly after adding 20% sand. Moreover, as the initial degree of saturation increased, the volumetric water content decreased, and the characteristic curves became identical when the initial saturation degree reached 90%. Finally, to minimize the water retention capacity of expansive soils, the study recommended adding a percentage of sand not less than 30% to the expansive clay sample.

Interfacial characterization of soil-3D printing materials

3D printing has emerged as a revolutionary technique for producing products with specific shapes and mechanical properties tailored to various needs. Its ability to fabricate intricate structures and forms has garnered considerable attention, leading to numerous research efforts exploring its potential benefits in geotechnical applications. These endeavours highlight the possibilities of utilizing 3D printing technology to create innovative and customized materials for soil reinforcement, such as geosynthetics, and fibres, as well as replicating soil particles, physical models of soil structures, and drainage systems in geo-structures. Additionally, beyond its role in geotechnical engineering, the interaction between geo-structures (foundations, retaining walls, embankments, tunnels, piles, infrastructures, etc.) and the surrounding soil under different loading and environmental conditions is of paramount importance. The interface between these structures and the soil plays a critical role in load transfer and overall stability. Therefore, this study focuses on investigating the interface between soil and 3D printed components through direct shear testing. The experimental campaign aims to examine how different factors, including the type of 3D printing materials, material rigidity, and surface texture of the printed components, influence the shear behaviour of the soil-3D printing material interface. The findings suggest that Young’s modulus of the 3D printed materials plays a crucial role in determining the response of the soil-3D printed parts interface. Furthermore, an optimized design is proposed to achieve the desired shearing resistance at the interface. The insights gained from this investigation have practical implications for optimizing the design of 3D-printed components in geotechnical engineering applications.

Artificial neural network for predicting the thermal conductivity of soils based on a systematic database

Thermal conductivity is a significant soil property that affects subsurface temperature distribution and plays an essential role in geotechnical engineering. Accurate evaluation of thermal conductivity is a challenging task since it can be affected by many factors. Although many prediction methods for thermal conductivity have been proposed, most of them are derived from limited experimental results and applied to specific soils. A unified prediction model that is suitable for various soils is still unavailable. This study establishes a general database including thermal conductivity and corresponding physical parameters obtained from experimental measurements and field tests. The Spearman correlation coefficient ranks the importance of influencing factors. In addition, a typical artificial neural network model is conducted and trained by 2197 samples to predict the thermal conductivity of soils. Results show that the thermal conductivity of soils has strong correlations with saturation, porosity and density. The proposed machine learning model has remarkable performance compared to existing prediction models for estimating soil thermal conductivity. This study builds a relatively systematic database of soil thermal conductivity and establishes a unified model to access the thermal conductivity of soils.

Feedback Analysis of Geotechnical Structure Simulation Based on 3D Modeling and Visualization

In geotechnical engineering, the analysis and calculation of numerical data of geotechnical engineering has great reference value and has been widely used in various fields. In the development of computer technology, 3D modeling and visualization technology plays an important role in geotechnical engineering, in which numerical data is the basis and important data of geotechnical engineering, which plays an important role in the future development of geotechnical engineering. In this paper, the numerical data simulation of geotechnical engineering structure is studied and analyzed.

Role of Geotechnical Engineering in BIM process modelling

BIM “Building Information Model” creates a significant step forward in the whole process of construction. The role of geotechnical engineering will be shown as for classical building engineering so for civil engineering structures. In the first case all upper structures are in interaction with ground (subsoil), when foundation structures are basic element of this interaction. The 3D Ground model and 3D Foundation structure model create therefore one of the first individual parametric elements around basic (coordinating) BIM model. Some specificity will be shown as the impact of step by step creation (nD dimension) of the Ground model for the earliest building conception. Roughly the same is valid for civil engineering structures. Some specificity will be shown for earth structures of transport engineering, as a selection of borrow pit, definition of soil compaction for fill, fill compaction or any other methods of soil improvement and its control as they create important elements for the safe and optimal embankment design and performance. Final 3D Ground model together with 3D Geotechnical structure model (real performance) create the important base for the future decision making, when some changes will occur.

Predicting the bearing capacity of pile installed into cohesive soil concerning the spatial variability of SPT data (A case study)

Nowadays, in situ tests have played a viable role in geotechnical engineering and construction technology. Besides lab tests conducted on undisturbed soil samples, many different kinds of in-situ tests were used and proved to be more efficient in foundation design such as pressuremeter PMT, cone penetration test CPT, standard SPT, etc. Among them, a standard penetration test (SPT for short) is easy to carry out at the site. For decades, it has proved reliable to sandy soil, but many viewpoints and opinions argued that the test was not appropriately applicable to cohesive soil because of scattered and dispersed data of SPT blow counts through different layers. This paper firstly studies how reliable the SPT data can predict the physical and mechanical properties; secondly, the soil strength is determined in terms of corrected N-SPT values, and finally the bearing capacity of a pile penetrating cohesion soil. By analyzing data from 40 boreholes located in 18 projects in Ho Chi Minh City, South VietNam, coefficients of determination between SPT numbers and physical and mechanical properties of different soil kinds are not the same: R2 = 0.623 for sand, =0.363 for sandy clay and =0.189 for clay. The spatial variability of soil properties is taken into account by calculating the scale of fluctuation θ=4.65m beside the statistically-based data in horizontal directions. Finally, the results from two theoretical approaches of predicting pile bearing capacity were compared to those of finite element program Plaxis 3D and static load test at site. Correlation between the capacity computed by using corrected N-values instead of soil strength and results of static load test has proved to be well suitable in evaluating the bearing capacity of driven and jack-in piles, particularly installing in the cohesive soil using the SPT blows.

A novel rockbolt formulation for a GPU-accelerated, finite-discrete element method code and its application to underground excavations

Rockbolting is widely used in civil and mining engineering to increase the inherent strength of the rock mass and reduce deformations around underground excavations. Rockbolt design by means of computer-aided numerical simulations has been playing an increasingly important role in geotechnical engineering. The research work presented herein introduces a novel rockbolt logic for the finite-discrete element method (FDEM), a numerical modelling approach capable of explicitly capturing brittle fracturing in complex geological media. Adoption of a GPU-based implementation was required to achieve substantial simulation speed-ups compared to conventional CPU computing. Rockbolts are discretized by 1D structural elements which are coupled to the solid finite element mesh by dedicated spring-slider connectors representing the bolt anchoring system. The formulation is verified by comparing simulated stress distributions with closed-form solutions for the cases of (i) a pull-out test on a fully-grouted rockbolt and (ii) a circular tunnel excavated in a bolted elastic medium. The effectiveness of the method for practical design applications is demonstrated by simulating the behavior of a bolted underground excavation in a heavily jointed rock mass. The effect of bolt spacing on the fracturing and deformational response of the rock mass is analyzed together with the force distributions in the rockbolts.

A NEW APPROACH FOR PARTICLE SIZE CHARACTERIZATION OF SOIL BASED ON DYNAMIC IMAGE ANALYSIS (DIA)

Particle size distribution (PSD) affects soil behaviour and plays a main role in geotechnical engineering. In site investiga- tions of large engineering structures, in earthquakes and liquefaction research and before filter material selection, it is necessary to make a number of PSD analyses. There are two popular techniques to determine PSD in the lab: sieving for the coarse-grained samples and hydrometer analysis for fine-grained samples. However, determining the PSD of soil in the lab has some challenges such as time, labour, difficulty and errors related to the analysis. The newly developed dy- namic image analysis (DIA) method based on wavelet transformation (WT) analysis is used as the main approach for determining particle size distribution. The DIA method contains saving the image and processing it with the software for a specified goal. The DIA method holds many advantages over the hydrometer analysis, including automating the test, reducing errors, monitoring and evaluating the particles at any time. In this paper, the PSD of fine-grained soil with a plasticity index (PI(=30 has been determined. The images of soil were prepared with a digital camera at a different time when particles settled through a sedimentation cylinder and were analysed with MATLAB software. The results were compared with the hydrometer analysis. The results showed that at t=15 min, a complete overlapping was seen between the DIA method and hydrometer analysis. The D20, D50 and D80 values by the DIA method were determined respectively, 0.0017, 0.012 and 0.031 mm at t=15 min. The results demonstrated that the DIA technique can be implemented for all types of fine-grained soils, more easily than the hydrometer analysis. The differences between the methods’ results were raised due to the amount of data provided by them.

The role of geotechnical engineering in sustainable and resilient cities

Geotechnical engineering is a fundamental subject in civil and environmental engineering that engineers are required to refer to when any type of retro tting, design or construction of projects and developments are encountered in a city or in a rural area. Indeed in many projects like geotechnical structures, such as earth dams, geotechnical engineering is the main subject. In this paper, the role of geotechnical engineering in sustainable and resilient cities is elaborated mainly through a series of questions and answers. Also, some related geotechnical engineering research, that is in hands in Civil Engineering Department of Sharif University, is discussed in this paper. A unique geotechnical engineering project that is designed and supervised in the city of Tehran by the author is also introduced herein to indicate how an accurate design and construction of a geotechnical structure can result in a sustainable and resilient condition. However, due to the variety of the subjects involved under the title of the paper, some of the subjects are touched briefly.

Calculation of Clay Permeability Using a Rectangular Particle-Water Film Model by the Double-Scale Asymptotic Expansion Method

Permeability of soil plays an important role in geotechnical engineering and is commonly determined by methods combining measurements with theory. Using the double-scale asymptotic expansion method, the Navier-Stokes equation is numerically solved to calculate the permeability, based on the homogenization method and the assumption that the homogeneous microstructure of the relevant porous media is represented accurately as the Representative Elemental Volume (REV). In this study, the commonly used square model is tested in the calculation of sea clay permeability. The results show large deviations. It is suspected that the square model could not represent the flattened shape of the clay particles and the bound water film wrapping around them. Hence, the Rectangle Particle-Water Film Model (i.e., the R-W model) is proposed. After determining the horizontal and vertical characteristic length of the unit cell using two pairs of initial data, the permeabilities of other different void ratios could be inversely calculated. The results of three types of clay obtained using the R-W model agree well with the experimental data. This shows the efficient feasibility and accuracy of the R-W model by providing a good representation of the clay particles when using the double-scale asymptotic expansion method to calculate clay permeability.

Shear zone evolution of granular soils in contact with conventional and textured CPT friction sleeves

Interfaces, and the shearing of soil against them, play a crucial role in geotechnical engineering. As such, understanding the fundamental mechanisms of interface behavior, such as the size, shape, and extent of soil shear zones against geomaterial surfaces can lead to better understanding and design of geotechnical systems and testing methods. The current study presents a series of laboratory studies aimed at spatially quantifying shear zones created through soil–geomaterial interface shearing including mobilized interface strengths with a focus on CPT friction sleeve behavior. Parametric investigations of particle shape and size effects were carried out over a range of counterface surface roughness values. The results show that conventional “smooth” CPT friction sleeves induce solely particle sliding in coarse grained soils, while non-clogging textured friction sleeves can create a combination of particle shearing and sliding that can allow for direct interface measurements in-situ. By varying the amount of texture on an interface, the extent of particle shearing can be controlled, allowing for improved understanding and treatment of interfaces in geotechnical testing and design.

Back Analysis of Geomechanical Parameters Using Hybrid Algorithm Based on Difference Evolution and Extreme Learning Machine

Since the geological bodies where tunnels are located have uncertain and complex characteristics, the inverse problem plays an important role in geotechnical engineering. In order to improve the accuracy and speed of surrounding rock identification, the back analysis objective function with usage of the displacement and stress monitoring data has been constructed, with a hybrid algorithm proposed. An extreme learning machine (ELM) is employed with optimal architecture trained by the difference evolution (DE) arithmetic. First, the three-dimensional numerical simulation is used in the creation of training and testing samples for ELM model construction. Second, the nonlinear relationship between rock parameters and displacement is constructed by numerical simulation. Finally, the geophysics parameters are obtained by DE optimization arithmetic taking into consideration the monitoring data including both displacement and pressure. This method had been applied in the Fusong highway tunnel in Fusong City of China’s Jilin Province, with a good effect obtained. It takes full advantage of DE and ELM and has both calculation speed and precision in the back analysis.

Design and Manufacture of a New Large-Scale Three-Dimensional Geomechanics Model Test System

Geomechanics modeling has played important role in geotechnical engineering. In order to investigate on the stability of underground caverns at great depth, a large-scale geomechanics model test system was designed and manufactured. The system mainly consisted of a steel structural frame and a hydraulic loading control system, which can apply active loading on six sides with a true three-dimensional stress state. Newly developed combinational ball sliding walls were installed on each of the major loading surfaces, which were significantly reduced the friction due to model deformation. The system has apparent technical advantages such as high stiffness, great stability, and flexibility of assembly, and easy adjustment of its dimensions.

Mexico City: Geotechnical Concerns in the Preservation of Monuments

This article presents and describes four case histories, which demonstrate that the role of geotechnical engineering in the preservation of architectural monuments in Mexico City is of paramount importance. Extremely soft soils and regional subsidence have combined to induce damaging differential settlements in a large number of monuments built in the former lake area. Hence, preservation of monuments in the city includes devising geotechnical solutions for correcting, reducing, or arresting differential settlements. The article points out the advantages and limitations of traditional solutions such as surface footings or the use of deep point bearing piles with devices for regulating the magnitude of loads applied on their heads. Other less well known solutions (underexcavation, mortar injection, and the use of isolation trenches) are also described and assessed critically.

The Role Of Geotechnical Engineering In The PreservationOf Our Architectural Heritage

Geotechnical Engineering is probably the youngest branch of Civil Engineering, yet it has already provided solutions to a wide range of different problems. This paper highlights the contributions of Geotechnical Engineering to the preservation of monuments, ancient buildings, cities and historic sites. Special attention is given to the activities of a Technical Committee on the Preservation of Historic Sites (TC-19) of the International Society of Soil Mechanics and Geotechnical Engineering (ISSMGE), which has played a major influence in promoting a culture of conservation of our architectural heritage within the geotechnical community. A methodological approach towards a widespread use of geotechnical knowledge to face the problems related to the preservation of our architectural heritage is presented and discussed, as the result of a careful review of relevant contributions in this field. In order to focus the attention on some key points of the suggested approach, reference is frequently made to a well-known case history.

環境問題における地盤工学の役割

環境問題における地盤工学の役割

Plummet Balance—A Potential Tool for Subsieve Particle Size Analysis

Abstract Particle size distribution analysis as an inferential soil parameter plays a dominant role in geotechnical engineering. This investigation encompasses laboratory study of subsieve particle size analysis by hydrometer, pipet, and plummet balance methods to assess their relative performances and also to examine the critical factors that influence the results obtained by the plummet method. The results of this investigation indicate that for a plummet immersion of 20 cm the particle size distribution would be similar to that obtained by hydrometer and pipet methods. The marginal differences would in no way affect either the classification of the soil or the inferred properties of soils.