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In situ digital testing method for quality assessment of soft soil improvement with polyurethane

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Journal of Rock Mechanics and Geotechnical engineering 2024年第5期16卷 1732-1748页

作者： X.F.Wang C.J.Wang W.V.Yue Z.J.Zhang Z.Q.Yue Department of civil engineering China University of Geosciences (Beijing)BeijingChina Department of Water Science and engineering Zhengzhou UniversityZhengzhouChina Department of Geotechnical engineering Tongji UniversityShanghaiChina Department of civil engineering The University of Hong KongChina

This study purposes an in situ testing method on quality assessment of soil *** drilling data includes the spatial distribution and in situ strength of untreated and treated soil along three different drillholes measured by on-site drilling monitoring *** factual drilling data can characterize the degree of soil improvement by penetration injection with permeable *** from on-site drilling monitoring shows that the linear zones represent constant drilling speeds shown in the plot of drill bit advancement *** drilling time,which indicates the spatial distributions of soil *** soil profile at the study site is composed of four layers,which includes fill,untreated silty clay,treated silty clay,and mucky *** results of soil profile are verified by the parallel site *** constant drilling speeds profile the coring-resistant strength of drilled *** comparing with the untreated silty clay,the constant drilling speeds of the treated silty clay have been decreased by 13.0-62.8%.Two drilling-speed-based indices of 61.2%and 65.6%are proposed to assess the decreased average drilling speed and the increased in situ strength of treated silty *** tests,*** compressive strength(UCS)test,have been performed with core sample to investigate and characterize in situ strength by comparing that with drilling *** show that the average predicted strengths of treated silty clay are 2.4-6.9 times higher than the average measured strength of untreated silty *** UCS-based indices of 374.5%and 344.2%verified the quality assessment(QA)results by this new in situ *** method provides a cost-effective tool for quality assessment of soil improvement by utilizing the digital drilling data.

关键词： Drilling process monitoring system Hydraulic rotary drilling process Constant drilling speed Soil improvement Quality assessment

Sensitivity of optimal double-layer grid designs to geometrical imperfections and geometric nonlinearity conditions in the analysis phase

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Frontiers of Structural and civil engineering 2024年第8期18卷 1209-1224页

作者： Amirali REZAEIZADEH Mahsa ZANDI Majid ILCHI GHAZAAN School of civil engineering Iran University of Science and TechnologyTehran 16846-13114Iran

This study focuses on exploring the effects of geometrical imperfections and different analysis methods on the optimum design of Double-Layer Grids(DLGs),as used in the construction industry.A total of 12 notable metaheuristics are assessed and contrasted,and as a result,the Slime Mold Algorithm is identified as the most effective approach for size optimization of *** evaluate the influence of geometric imperfections and nonlinearity on the optimal design of real-size DLGs,the optimization process is carried out by considering and disregarding geometric nonlinearity while incorporating three distinct forms of geometrical imperfections,namely local imperfections,global imperfections,and combinations of *** light of the uncertain nature of geometrical imperfections,probabilistic distributions are used to define these imperfections randomly in direction and *** results demonstrate that it is necessary to account for these imperfections to obtain an optimal ***’s worth noting that structural imperfections can increase the maximum stress ratio by up to 70%.The analysis also reveals that the initial curvature of members has a more significant impact on the optimal design of structures than the nodal installation error,indicating the need for greater attention to local imperfection issues in space structure construction.

关键词： double-layer grid sizing optimization metaheuristic algorithms geometrical imperfections analysis approach

A Comprehensive Study on the Consequences of Gap-Graded Sands Considering the Loss of Fine Particles

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Journal of Earth Science 2024年第2期35卷 597-612页

作者： Weiping Liu Yu Gan Yunwei Cui Faming Huang Lina Hu School of civil engineering and Architecture Nanchang UniversityNanchang330031China

Water and sand leakage disasters are likely to occur during construction in water-rich sand layer areas,resulting in ground *** stress-strain action characteristics of discontinuous graded sand under different internal erosion degrees,and the evolution mechanism of water and sand leakage disasters caused by the internal erosion need to be further ***,this paper takes the discontinuous graded sand in a water rich sand layer area in Nanchang City of China as the research *** the influence of different fine particle losses(0,10%,20%and 30%)under the internal erosion of sand,the salt solution method is used to realize the specified loss of fine particles in the internal *** stress-strain behavior after the loss of fine particles due to internal erosion is studied by triaxial shear ***,the physical model test and PFC-CFD method are both used to study the evolution rules of water and sand leakage disaster considered the influence of internal erosion *** show that:(1)under the same confining pressure,the peak failure strength of sand samples decreases along with the increase of fine particle loss.(2)In the water and sand leakage test of saturated sand,a natural filter channel is formed above the observed soil *** greater the loss of fine particles,the steeper and wider the collapse settlement area.(3)The relationship between the cumulative amount of water and sand leakage and time is *** total mass loss of sand increases along with the increase of internal erosion degree.(4)After the soil arch is formed around the damaged opening,the sand continues to converge above the soil arch under the action of water flow,resulting in the dense convergence of contact force chains.

关键词： sandy soil internal erosion stress and strain water and sand leakage PFC3D engineering geology

A cumulative damage model for predicting and assessing raveling in asphalt pavement using an energy dissipation approach

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Frontiers of Structural and civil engineering 2024年第6期18卷 949-962页

作者： Kailing DENG Duanyi WANG Cheng TANG Jianwen SITU Luobin CHEN School of civil engineering and Transportation South China University of TechnologyGuangzhou 510640China

Raveling is a common distress of asphalt pavements,defined as the removal of stones from the pavement *** predict and assess raveling quantitatively,a cumulative damage model based on an energy dissipation approach has been developed at the meso *** construct the model,a new test method,the pendulum impact test,was employed to determine the fracture energy of the stone-mastic-stone meso-unit,while digital image analysis and dynamic shear rheometer test were used to acquire the strain rate of specimens and the rheology property of mastic,*** of the model reveals that when the material properties remain constant,the cumulative damage is directly correlated with loading time,loading amplitude,and loading ***,damage increases with superimposed linear and cosine variations over time.A higher stress amplitude results in a more rapidly increasing rate of damage,while a lower load frequency leads to more severe damage within the same loading ***,an example of the application of the model has been presented,showing that the model can be utilized to estimate failure life due to *** model is able to offer a theoretical foundation for the design and maintenance of anti-raveling asphalt pavements.

关键词： asphalt pavement raveling cumulative damage dissipation energy theory

Frost heaving and crack initiation characteristics of tunnel rock mass in cold regions under low-temperature degradation

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Journal of Mountain Science 2024年第8期21卷 2844-2854页

作者： CHEN Wenhua XIANG Tian School of civil engineering Beijing Jiaotong UniversityBeijing 202303China

Water freezing in rock fractures causes volumetric expansion and fracture development through frost *** study introduces a novel analytical model to investigate how uneven freezing force and surrounding rock pressure influence fracture initiation,based on mass conservation,elasticity,and water-ice phase transition principles.A model for rock fracture initiation considering freezing temperature,uneven freezing expansion,in-situ stress,and lateral pressure was proposed based on fracture *** for stress intensity factors were developed and validated using the phase field *** effects of rock elastic modulus anisotropy and critical fracture energy density on fracture initiation were also *** results show that the values of KI and KII exhibit an upward trend as the freezing temperature,uneven expansion,in-situ stress,and lateral pressure *** uneven freezing expansion has the most significant influence on KI and KII values among these *** the uneven freezing expansion coefficient increases to 0.5,the fracture initiation mode shifts from tensile fracture to shear *** the lateral pressure coefficient increases to 1,the fracture initiation mode shifts from tensile fracture to shear *** elastic modulus anisotropy causes fractures to propagate in a clockwise direction,forming a'butterfly'*** fracture energy density an isotropy causes counterclockwise deviation in propagation direction,resulting in branching paths and an'H'-shaped pattern.

关键词： Rock fractures Fracture water Uneven freezing expansion Phase field method Initiation angle Anisotropy

Sparse Modal Decomposition Method Addressing Underdetermined Vortex-Induced Vibration Reconstruction Problem for Marine Risers

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China Ocean engineering 2024年第2期38卷 285-296页

作者： DU Zun-feng ZHU Hai-ming YU Jian-xing State Key Laboratory of Hydraulic engineering Intelligent Construction and Operation School of Civil EngineeringTianjin UniversityTianjin 300350China

When investigating the vortex-induced vibration(VIV)of marine risers,extrapolating the dynamic response on the entire length based on limited sensor measurements is a crucial step in both laboratory experiments and fatigue monitoring of real *** problem is conventionally solved using the modal decomposition method,based on the principle that the response can be approximated by a weighted sum of limited vibration ***,the method is not valid when the problem is underdetermined,i.e.,the number of unknown mode weights is more than the number of known *** study proposed a sparse modal decomposition method based on the compressed sensing theory and the Compressive Sampling Matching Pursuit(Co Sa MP)algorithm,exploiting the sparsity of VIV in the modal *** the validation study based on high-order VIV experiment data,the proposed method successfully reconstructed the response using only seven acceleration measurements when the conventional methods failed.A primary advantage of the proposed method is that it offers a completely data-driven approach for the underdetermined VIV reconstruction problem,which is more favorable than existing model-dependent solutions for many practical applications such as riser structural health monitoring.

关键词： motion reconstruction vortex-induced vibration(VIV) marine riser modal decomposition method compressed sensing

Impact resistance performance and optimization of the sand-EPE composite cushion in rock sheds

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Journal of Mountain Science 2024年第2期21卷 676-689页

作者： YU Bingxin ZHOU Xiaojun TANG Jianhui ZHANG Yujin ZHANG Yuefeng School of civil engineering Southwest Jiaotong UniversityChengdu 610031China

Rock sheds are widely used to prevent rockfall disasters along roads in mountainous *** improve the capacity of rock sheds for resisting rockfall impact,a sand and expandable polyethylene(EPE)composite cushion was proposed.A series of model experiments of rockfall impact on rock sheds were conducted,and the buried depth of the EPE foam board in the sand layer was *** impact load and dynamic response of the rock shed were *** results show that the maximum impact load and dynamic response of the rock shed roof are all significantly less than those of the sand ***,as the distance between the EPE foam board and rock shed roof decreases,the maximum rockfall impact force and impact pressure gradually decrease,and the maximum displacement,acceleration and strain of the rock shed first decrease and then change *** addition,the vibration acceleration and vertical displacement of the rock shed roof decrease from the centre to the edge and decrease faster along the longitudinal direction than that along the transverse *** conclusion,the buffering effect of the sand-EPE composite cushion is better than that of the pure sand cushion,and the EPE foam board at a depth of 1/3 the thickness of the sand layer is appropriate.

关键词： Rockfall Rock shed Impact Composite cushion Buffering effect Dynamic response

Investigation of material composition,design,and performance of open-graded asphalt mixtures for semi-flexible pavement:A comprehensive experimental study

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Journal of Traffic and Transportation engineering(English Edition) 2024年第1期11卷 92-116页

作者： Mohammad Taghipoor Abolfazl Hassani Mohammad M.Karimi Department of civil and Environmental engineering Tarbiat Modares UniversityTehranIran

The primary goal of this study is the design and construction of semi-flexible pavement(SFP)mixture in accordance with the engineering and mechanical *** study involves the use of a range of gradation curves,air void contents,cellulose and synthesized fibers,and neat and modified asphalt binders to prepare the open-graded asphalt(OGA)*** analyze the characteristics of these mixtures,a variety of test,namely binder drainage,semi-circular bending(SCB),Cantabro,wheel tracking,indirect tensile strength(ITS),and permeability tests were ***,to analyze the prepared grouting material,flexural strength,compressive strength,and fluidity tests were *** the final stage,SFP was compared to HMA in terms of engineering characteristics and *** to the results,SFP was more resistant to skid,rutting,fire,and moisture damage,while HMA had a better performance in fracture tests,including SCB *** to the results of the mechanical performance tests conducted on OGA mixtures,the highest and lowest values for air void content to achieve the highest mechanical performance level were 30%-35%and 25%,***,based on the laboratory results,it was determined that the required void ratio for constructing OGA mixtures was 24%-26%based on the bitumen type and fibers amount in the ***,SFP mixture can be regarded as a viable alternative to common pavements thanks to its high resistance to rutting and moisture damage,long freezing-thawing fatigue life,and adequate fire and skid resistance.

关键词： Semi-flexible pavement mixture Open-graded asphalt mixture engineering properties Cantabro test Hot mix asphalt

Wind-sand flow simulation and radius optimization of highway embankment under different vertical curve radius

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Journal of Mountain Science 2024年第8期21卷 2533-2546页

作者： LI Liangying LI Qi WANG Xu XIN Guowei WANG Zhenqiang School of civil engineering Lanzhou Jiaotong UniversityLanzhou 730070China

It is of great practical value to explore the correlation between the vertical curve radius of desert highway and the increase of sand accumulation in local lines,and to select the appropriate vertical curve radius for reducing the risk of sand *** this study,three-dimensional models of desert highway embankments with different vertical curve radii were constructed,and Fluent software was used to simulate the wind-sand flow field and sand accumulation distribution of vertical curve *** results show that:(1)Along the direction of the road,the concave and the convex vertical curve embankments have the effect of collecting and diverging the wind-sand flow,*** the radius of the concave vertical curve is 3000 m,5000 m,8000 m,10000 m and 20000 m,the wind velocity in the middle of the vertical curve is 31.76%,22.58%,10.78%,10.53%and 10.44%,higher than that at both *** the radius of the convex vertical curve is 6500 m,8000 m,10000 m,20000 m and 30000 m,the wind velocity at both ends of the vertical curve is 14.06%,9.99%,6.14%,3.22%and 2.41%,higher than that in the *** diversion effect also decreases with the increase of the radius.(2)The conductivity of the concave and convex vertical curve embankments with different radii is greater than 1,which is the sediment transport *** conductivity increases with the increase of radius and gradually tends to be *** the radius of the concave and convex vertical curves reaches 8000 m and 20000 m respectively,the phenomenon of sand accumulation is no longer *** the same radius condition,the concave vertical curve embankment is more prone to sand accumulation than the convex one.(3)Considering the strength of the collection and diversion of the vertical curve embankment with different radii,and the sand accumulation of the vertical curve embankment in the desert section of Wuma Expressway,the radius of the concave vertical curve is not less than 8000 m,and the r

关键词： Highway engineering Vertical curve Numerical simulation Embankment wind-sand flow Radius optimization