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CONTENTS
Volume 32, Number 6, March25 2023
 


Abstract
A circular tank foundation resting on the ground and subjected to axisymmetric horizontal and vertical loads and moments is analyzed using the variational principles of mechanics. The circular foundation is assumed to behave as a Kirchhoff plate with in-plane and transverse displacements. The soil beneath the foundation is assumed to be a multi-layered continuum in which the horizontal and vertical displacements are expressed as products of separable functions. The differential equations of plate and soil displacements are obtained by minimizing the total potential energy of the plate-soil system and are solved using the finite element and finite difference methods following an iterative algorithm. Comparisons with the results of equivalent two-dimensional finite element analysis and other researchers establish the accuracy of the method.

Key Words
circular plate; continuum; minimum potential energy; multi-layered soil; soil structure interaction

Address
Hesham F. Elhuni: Department of Civil and Environmental Engineering, Univ. of Waterloo, Waterloo, ON N2L 3G1, Canada
Bipin K. Gupta: Department of Civil Engineering, IIT Kanpur, Kanpur 208016, UP, India
Dipanjan Basu: Department of Civil and Environmental Engineering, Univ. of Waterloo, Waterloo, ON N2L 3G1, Canada

Abstract
Enhanced vertical load capacity of the ground reinforced with the stone columns drew great attention by the researchers as it deals with many of the geotechnical difficulties associated with the weak ground. Recently, it has been found that the stone columns are also prone to fail under the shear load when employed beneath the embankments or the foundations susceptible to lateral loads. In this study, the effect of various encasement conditions on the lateral deflection of stone columns is investigated. A method of dual layers of encasement has been introduced and its the effect on lateral load capacity of the stone columns has been compared with those of the single encased stone column and the un-encased stone columns. Large shear box tests were utilised to generate the shear deformation on the soil system under various normal pressure conditions. The stiffness of the soil-stone column combined system has been compared for various cases of encasement conditions with different diameters. When subjected to lateral deformation, the encased columns outperformed the un-encased stone columns installed in loose sand. Shear stress resistance is up to 1.7 times greater in dual-layered, encased columns than in unencased columns. Similarly, the secant modulus increases as the condition changes from an unencased stone column to single-layer encasement and then to dual-layer encasement, indicating an improvement in the overall soil-stone column system.

Key Words
dual layer; encasement; lateral load; shear modulus of elasticity; stone column

Address
Akash Jaiswal and Rakesh Kumar: Department of Civil Engineering MANIT, Bhopal,462003, India

Abstract
The resilient modulus (MR) of various pavement materials plays a significant role in the pavement design by a mechanistic-empirical method. The MR determination is done by experimental tests that need time and money, along with special experimental tools. The present paper suggested a novel hybridized extreme gradient boosting (XGB) structure for forecasting the MR of modified base materials subject to wet-dry cycles. The models were created by various combinations of input variables called deep learning. Input variables consist of the number of W-D cycles (WDC), the ratio of free lime to SAF (CSAFR), the ratio of maximum dry density to the optimum moisture content (DMR), confining pressure (o3), and deviatoric stress (od). Two XGB structures were produced for the estimation aims, where determinative variables were optimized by particle swarm optimization (PSO) and black widow optimization algorithm (BWOA). According to the results' description and outputs of Taylor diagram, M1 model with the combination of WDC, CSAFR, DMR, o_3, and o_d is recognized as the most suitable model, with R^2 and RMSE values of BWOA-XGB for model M1 equal to 0.9991 and 55.19 MPa, respectively. Interestingly, the lowest value of RMSE for literature was at 116.94 MPa, while this study could gain the extremely lower RMSE owned by BWOA-XGB model at 55.198 MPa. At last, the explanations indicate the BWO algorithm's capability in determining the optimal value of XGB determinative parameters in M_R prediction procedure.

Key Words
extreme gradient boosting; modified base materials; predicting; resilient modulus; wet-dry cycles

Address
Mahzad Esmaeili-Falak: Department of Civil Engineering, North Tehran Branch, Islamic Azad University, Tehran, Iran
Reza Sarkhani Benemaran: Department of Civil Engineering, Faculty of Geotechnical Engineering, University of Zanjan, Zanjan, Iran

Abstract
Low liquid limit silt, widely distributed in the middle and down reaches of Yellow River, has the disadvantages of poor grading, less clay content and poor colloidal activity. It is very easy to cause vehicle jumping at the bridge-embankment transition section when the low liquid limit silt used as the backfill at the abutment back. In this paper, a series of laboratory tests were carried out to study the physical and mechanical properties of the low liquid limit silt used as back filling. Ground granulated blast furnace slag (GGBFS) was excited by active MgO and hydrated lime to solidify silt as abutment backfill. The optimum ratio of firming agent and the compaction and mechanical properties of reinforced soil were revealed through compaction test and unconfined compressive strength (UCS) test. Scanning electron microscope (SEM) test was used to study the pore characteristics and hydration products of reinforced soil. 6% hydrated lime and alkali activated slag were used to solidify silt and fill the model of subgrade respectively. The pavement settlement regulation and soil internal stress-strain regulation of subgrade with different materials under uniformly distributed load were studied by model experiment. The effect of alkali activated slag curing agent on curing silt was verified. The research results can provide technical support for highway construction in silt area of the Yellow River alluvial plain.

Key Words
bridge-subgrade transition section; GGBFS; low liquid limit silt; model test; solidified silt; vehicle jumping

Address
Shu-jian Wang: Geotechnical and Structural Engineering Research Center, Shandong University, Jinan 250061, China;
Shandong Hi-speed Group CO., Ltd., Jinan 250101, China
Yong Sun: Geotechnical and Structural Engineering Research Center, Shandong University, Jinan 250061, China
Zhen-bao Li: Geotechnical and Structural Engineering Research Center, Shandong University, Jinan 250061, China;
Research Institute of New Material and Intelligent Equipment, Shandong University, Dezhou 251100, China
Kai Xiao: Shandong Luqiao Group CO., Ltd., Jinan 250021, China
Wei Cui: School of Qilu Transportation, Shandong University, Jinan 250002, China


Abstract
Initial geometrical imperfection is an important factor affecting the structural characteristics of plate and shell structures. Studying the effect of geometrical imperfection on the structural characteristics of cylindrical shell is beneficial to explore the thermal post-buckling response characteristics of cylindrical shell. Therefore, we devote to investigating the thermal post-buckling behavior of graphene platelets reinforced mental foam (GPLRMF) cylindrical shells with geometrical imperfection. The properties of GPLRMF material with considering three types of graphene platelets (GPLs) distribution patterns are introduced firstly. Subsequently, based on Donnell nonlinear shell theory, the governing equations of cylindrical shell are derived according to Eulerian-Lagrange equations. Taking into account two different boundary conditions namely simply supported (S-S) and clamped supported (C-S), the Galerkin principle is used to solve the governing equations. Finally, the impact of initial geometrical imperfections, the GPLs distribution types, the porosity distribution types, the porosity coefficient as well as the GPLs mass fraction on the thermal post-buckling response of the cylindrical shells are analyzed.

Key Words
cylindrical shells; Galerkin' method; graphene platelet; initial geometrical imperfection; metal foams; thermal post-buckling

Address
Yi-Wen Zhang, Gui-Lin She, Lei-Lei Gan and Yin-Ping Li: College of Mechanical and Vehicle Engineering, Chongqing University, Chongqing 400044, China

Abstract
Volleyball is an international sport with many fans. This sport has made significant progress in schools and clubs. Volleyball is suitable for all age groups and can be used in different environments. It has many social and physical benefits. During the game provides special physical training for the players and is considered one of the most exciting games. Another type of volleyball is beach volleyball, a beach sport and one of the Olympic sports held on the sand with the same rules as volleyball. This sport is usually played in coastal areas, especially with wide sandy beaches. Because this sport is played in open spaces, the players stay in this space for a long time and are exposed to dangerous ultraviolet radiation. It is a wavelength of light in the range of electromagnetic waves with a wavelength between 10 and 400 nm. This wavelength is shorter than visible light and more protracted than X-ray. Ultraviolet (UV) rays are naturally present in sunlight and include about 10% of all waves emitted from the sun's surface. Prolonged exposure to ultraviolet light causes acute and chronic damage to the skin and vision and even destroys the entire immune system. Different covers of the earth's surface reflect different amounts of UV rays. For example, snow cover, sand, and seawater surface reflect this radiation. Therefore, the health of volleyball players is in danger due to this harmful radiation. This work aims to introduce a type of clothing made of nanoparticles that can repel ultraviolet rays and protect beach volleyball players whose health is at risk from this radiation.

Key Words
clothes; radiation damage; safe; ultraviolet radiation; volleyball beach

Address
He Huang: School of Physical Education Major,Leshan Normal University,Leshan 614000,Sichuan,China;
College of Innovation and Management, Suan Sunandha Rajabhat University, Bangkok 10300, Thailand

Abstract
Stepped earth slopes incorporated with anti-slide piles are widely utilized in landslide disaster preventions. Explicit consideration of the three-dimensional (3D) effect in the slope design warrants producing more realistic solutions. A 3D limit analysis of the stability of pile stabilized stepped slopes is performed in light of the kinematic limit analysis theorem. The influences of seismic excitation and surcharge load are both considered from a kinematic perspective. The upper bound solution to the factor of safety is optimized and compared with published solutions, demonstrating the capability and applicability of the proposed method. Comparative studies are performed with respect to the roles of 3D effect, pile location, pile spacing, seismic and surcharge loads in the safety assessments of stepped slopes. The results demonstrate that the stability of pile reinforced stepped slopes differ with that of single stage slopes dramatically. The optimum pile location lies in the upper portion of the slope around Lx/L = 0.9, but may also lies in the shoulder of the bench. The pile reinforcement reaches 10% universally for a looser pile spacing Dc/dp = 5.0, and approaches 70% when the pile spacing reaches Dc/dp = 2.0.

Key Words
limit analysis; pile; pseudo-static method; safety factor; slope stability

Address
Long Wang: School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, China;
Guangxi Key Laboratory of Disaster Prevention and Engineering Safety, Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education, College of Civil Engineering and Architecture, Guangxi University, Nanning 530004, China
State Key Laboratory of Geohazard Prevention and Geoenvironmental Protection, Chengdu University of Technology,
Chengdu 610059, China

Abstract
In practice, the interference influence caused by adjacent footings of structures on geo-reinforced loose soil has a considerable impact on their behavior. Thus, the goal of this study is to evaluate the behavior of two strip footings in close proximity on both geocell and geogrid reinforced soil with different reinforcement layers. Geocell was made from geogrid material used to compare the performance of cellular and planar reinforcement on the bearing pressure of twin footings. Extensive experimental tests have been performed to attain the optimum embedment depth and vertical distance between reinforcement layers. Particle image velocimetry (PIV) analysis has been conducted to monitor the deformation, tilting and movement of soil particles beneath and between twin footings. Results of tests and PIV technique were verified using finite element modeling (FEM) and the results of both PIV and FEM were used to utilize failure mechanisms and influenced shear strain around the loading region. The results show that the performance of twin footings on geocell-reinforced sand at allowable and ultimate settlement ranges are almost 4% and 25% greater than the same twin footings on the same geogrid-reinforced sand, respectively. By increasing the distance between twin footings, soil particle displacements become smaller than the settlement of the foundations.

Key Words
bearing pressure; failure mechanism; finite element modeling; geosynthetics; interfering strip footings; particle image velocimetry (PIV)

Address
Mahmoud Ghazavi and Marzieh Norouzi: Faculty of Civil Engineering, K.N. Toosi University of Technology, Tehran 19967-15433, Iran
Pezhman Fazeli Dehkordi: Department of Civil Engineering, Shahrekord Branch, Islamic Azad University, Shahrekord 88137-33395, Iran


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