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The scheme for accurate and reliable predictions of tunnel stability based on an artificial aeural network (ANN) is presented in this study. Plastic solutions of the stability of unlined elliptical tunnels in sands are first derived by using numerical upper-bound (UB) and lower-bound (LB) finite element limit analysis (FELA). These numerical solutions are later used as the training dataset for an ANN model. Note that there are four input dimensionless parameters, including the dimensionless overburden factor γD/c′, the cover–depth ratio C/D, the width–depth ratio B/D, and the soil friction angle ϕ. The impacts of these input dimensionless parameters on the stability factor σs/c′ of the stability of shallow elliptical tunnels in sands are comprehensively examined. Some failure mechanisms are carried out to demonstrate the effects of all input parameters. The solutions will reliably and accurately provide a safety assessment of shallow elliptical tunnels.

In agricultural machinery design and optimization, the discrete element method (DEM) has played a major role due to its ability to speed up the design and manufacturing process by reducing multiple prototyping, testing, and evaluation under experimental conditions. In the field of soil dynamics, DEM has been mainly applied in the design and optimization of soil-engaging tools, especially tillage tools and furrow openers. This numerical method is able to capture the dynamic and bulk behaviour of soils and soil–tool interactions. This review focused on the various aspects of the application of DEM in the simulation of tillage and furrow opening for tool design optimization. Different contact models, particle sizes and shapes, and calibration techniques for determining input parameters for tillage and furrow opening research have been reviewed. Discrete element method predictions of furrow profiles, disturbed soil surface profiles, soil failure, loosening, disturbance parameters, reaction forces, and the various types of soils modelled with DEM have also been highlighted. This pool of information consolidates existing working approaches used in prior studies and helps to identify knowledge gaps which, if addressed, will advance the current soil dynamics modelling capability.

The construction of superstructures on soft soils demands the desired bearing capacity. This can be achieved through various approaches, including improving soil properties using chemical methods, or by employing techniques such as increasing footing dimensions or using micro piles which are uneconomical and time-consuming. To overcome this, enhancement of bearing capacity of soft soils was done by simple and economical technique i.e., cutting the existing soft soil and filling the Cohesive-frictional soil with a defined ratio of top layer thickness to width of the footing. To conduct this analysis, Plaxis 3D software was employed to investigate soil behaviour and simulate various scenarios, to identify the optimum thickness of the fill layer required to enhance the desired bearing capacity of the strata while ensuring a prescribed settlement and load imposed by the superstructure following the Indian Standards for constructing a multi-storied building. The investigation determined that the optimum top layer thickness to footing width is 2. The findings of this study will contribute valuable insights into geotechnical engineering practices, offering a practical and economical solution for enhancing the bearing capacity of soft soils in construction projects.

Lower bound finite element limit analysis in conjunction with second-order cone programming is developed and employed to investigate the stability of retained soils behind underground walls with an opening in cohesive-frictional soils. In this study, two-dimensional plane strain condition is setup for modelling the problem while the lower bound solution of the problem is obtained by employing the finite element approach of lower bound limit analysis. The lower bound optimization problem is cast as the second-order cone programming, and is solved by a conic programming algorithm. For practical use, the results of lower bound solution are summarized in the form of dimensionless stability charts of the load factor that is a function of the cover depth ratio of opening, overburden stress factor and soil friction angles. Plastic yielding zones predicted from the lower bound analysis are discussed and examined for these dimensionless parameters while the computed lower bound solutions are validated with an existing solution. Finally, a closed-form approximate expression is developed for predicting the lower bound solution of the load factor for the problem with practical ranges of cover depth ratios of opening, overburden stress factors, and soil friction angles. New opening stability factors with respect to soil cohesion and unit weight as a function of cover depth ratios of opening and soil friction angles are presented.

Soils with less than 15% fines content are recommended as backfill materials for mechanically stabilized walls to maintain optimum performance and avoid any serviceability problems. However, the shortage and/or the high cost of such soils have encouraged civil engineers to find safe methodologies to employing the available native soils. To the authors’ knowledge, these approaches have been reviewed in this paper, and their limitations have been discussed. Further, the article also examines the experimental techniques used to measure the interaction at the interface between the soil and the reinforcing elements due to their importance in fulfilling an accurate design.

In trenchless pipe jacking engineering practice, the formation of high-quality slurry jacket on the outer wall of pipe section is the key to effectively reducing the pipe-soil frictional resistance, improving the construction efficiency, reducing the construction risk and ensuring the construction safety. Herein, the multifunctional experimental apparatus for the pipe-soil frictional resistance testing is improved to ensure the smooth implementation of the subsequent experimental research. The influences of the structural parameters of grouting holes in circular and rectangular pipe sections on the pipe-soil frictional resistance and the states of slurry jackets around the various pipe sections are investigated respectively based on orthogonal experiment. Key findings include the pipe-soil frictional resistances increase with the increase of the spacing between adjacent grouting holes and the deflection angle of grouting holes, the layout of grouting holes has the greatest influence on pipe-soil frictional resistance, reasonable and uniform layout of grouting holes around the pipe sections can form more complete high-quality slurry jackets, to show better pipe-soil frictional resistance reduction effect. Moreover, the optimal structural parameters of grouting holes in circular and rectangular pipe sections are the same, i.e. the layout is triple grouting holes, the spacing between adjacent grouting holes S is 417 mm, and the deflection angle of grouting holes α is 40°. These insights could provide some scientific and valuable guidance for pipe-soil frictional resistance reduction during trenchless pipe jacking.

This paper presents an Artificial Neural Network (ANN)-based approach for predicting tunnel stability that is both dependable and accurate. Numerical solutions to the instability of unlined horseshoe tunnels in cohesive-frictional soils are established, primarily by employing numerical upper bound (UB) and lower bound (LB) finite element limit analysis (FELA). The training dataset for an ANN model is made up of these numerical solutions. Four dimensionless parameters are required in the parametric analyses, namely the dimensionless overburden factor γD/c′, the cover-depth ratio C/D, the width-depth ratio B/D, and the soil friction angle ϕ. The influence of these dimensionless parameters on the stability factor is explored and illustrated in terms of a design chart. Moreover, the failure mechanisms of a shallow horseshoe tunnel in cohesive-frictional soil that is influenced by the four dimensionless parameters are also provided. Therefore, the current stability solution, based on FELA and ANN models, is presented in this paper, allowing for the efficient and accurate establishment and evaluation of an optimum surcharge loading of shallow horseshoe tunnels in practice.

This paper presents the parametric modelling process of cantilever soldier pile walls based on CO2 and cost optimization with the Harmony Search Algorithm. The study attempted to fulfil the geotechnical and structural design requirements and sustainable usage necessities simultaneously. The variants of the optimum design process are selected as the cross-sectional characteristics of cantilever soldier piles such as the length and diameter of the pile, and the other design variables are the reinforcement detailing of the pile such as the diameter and the number of reinforcement bars. Besides the volume of the concrete, the unit prices of both reinforcement and concrete are evaluated as another part of the variants. The shear and flexural strength necessities, minimum cross section of the reinforcing bars and factor of safety values are identified as the constraints of the optimization. Different objective functions are defined to provide the minimum cost, the minimum CO2 emission and the integrated multi-objective evaluation of cost and CO2. In addition, the type of steel and concrete reinforcement on the optimum CO2 emission is investigated with the use of different material emission values that are selected from current literature studies. Consequently, the results of the optimization analyses are interrogated to investigate if the attainment of both minimum CO2 and cost balance can be achieved.

In recent decades, the most impactful effects of thermal gradients on the shear modulus of compacted soils have been increasingly well documented. The thermal repercussions on the corresponding damping ratios, however, have not been as thoroughly investigated. In this work, a series of thermo-controlled resonant column tests was conducted on statically compacted samples of three distinct types of cohesive-frictional soils, namely low plasticity clay, non-plastic silt, and clayey sand, to assess the effect of elevated soil temperatures on their respective small-strain damping ratios. Damping ratio for each soil type and test condition was determined via both the frequency response curves ( bandwidth method ) and the underdamped free-vibration cycles ( logarithmic decrement ) in order to perform a comparative analysis of damping assessment methods. The corresponding stress–strain hysteresis loops were also evaluated for further qualitative insights into any possible thermal sensitivities of their material damping in the field. Results show a mostly detrimental effect of increasing soil temperature on the small-strain stiffness of cohesive-frictional soils, with their damping ratio remaining virtually unchanged (clays) or experiencing a gradual increase (silts and sands) with increasing soil temperature.

A new approach is proposed to evaluate the non-limit active earth pressure in c–φ soil based on the horizontal slices method and limit equilibrium method, which takes into account arching effect, displacement, mobilized friction angle, tension cracks, and shear stress of the horizontal layer. The accuracy of the proposed method was demonstrated by comparing the experimental results and other theoretical methods. The comparison results showed that the proposed approach was appropriate for calculating the non-limit active earth pressure in c–φ soil and cohesionless soil. A parametric study was undertaken to access the effects of cohesion, mobilized friction angle, and shear stress of the horizontal layer for the lateral earth pressure, as well as the effects of displacement for the rupture angle and tension cracks. Moreover, by comparing calculated results of the different theoretical methods and numerical model, it indicated that the empirical formulations of the mobilized internal friction angle and soil–wall interface friction angle used to cohesionless soil were still suitable for c–φ soil.