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Study of the wall adhesive tensile contact of moist iron ore bulk solids

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Particuology 2020年第3期18卷 67-75页

作者： Tao Fang Wei Chen Jens Plinke Craig Wheeler Alan Roberts school of civil engineering East China Jiaotong UniversityNanchang 330013China school of engineering The University of NewcastleCallaghan 2308Australia

The adhesive tensile stress between moist bulk iron ore solids and wall surfaces are critical to control and avoid blockage in large throughput material handling plants.In this study,an experimental system was designed to investigate the adhesive tensile contact between a range of iron ore materials and wall lining specimens.The contact mechanism between the material specimen and the wall surface was initially characterised.The experimental results indicated that the adhesive tensile stress is dependent on both the moisture content and the applied major consolidation stress,with the former exhibiting more significant contribution to increasing the magnitude of stress.The surface roughness of the wall showed a negligible effect in determining the adhesive tensile stress.Additionally,the iron ore sample with a higher fines content was observed to be able to achieve a higher adhesive tensile stress compared to the coarse samples.Consequently,the insights resulting from the study demonstrated practical applicability through measures such as blending and/or beneficiation,which reduce the adhesive tensile stress and minimise blockages.

关键词： Wet sticky material Adhesive tensile stress Wall linings Liquid bridge force Capillary stress Soil texture

Large-scale model test study on the water pressure resistance of construction joints of karst tunnel linings

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Frontiers of Structural and civil engineering 2023年第8期17卷 1249-1263页

作者： Meng HUANG Mingli HUANG Ze YANG Yuan SONG Zhien ZHANG school of civil engineering Beijing Jiaotong UniversityBeijing 100044China Enterprise Key Laboratory Tianjin Municipal Engineering Design and Research InstituteTianjin 300392China school of civil engineering and architecture Anhui University of Science and TechnologyHuainan 232001China

Model tests and numerical calculations were adopted based on the New Yuanliangshan tunnel project to investigate the water pressure resistance of lining construction joints in high-pressure and water-rich karst tunnels.A large-scale model test was designed and conducted,innovatively transforming the external water pressure of the lining construction joint into internal water pressure.The effects of the embedded position and waterstop type on the water pressure resistance of the construction joint were analyzed,and the reliability of the model test was verified via numerical calculations.The results show that using waterstops can significantly improve the water pressure resistance of lining construction joints.The water pressure resistance of the lining construction joint is positively correlated with the lining thickness and embedded depth of the waterstop.In addition,the type of waterstop significantly influences the water pressure resistance of lining construction joints.The test results show that the water pressure resistance of the embedded transverse reinforced waterstop is similar to that of the steel plate waterstop,and both have more advantages than the rubber waterstop.The water pressure resistance of the construction joint determined via numerical calculations is similar to the model test results,indicating that the model test results have high accuracy and reliability.This study provides a reference for similar projects and has wide applications.

关键词： karst tunnel lining construction joint water pressure resistance large-scale model test numerical calculations

Earth Pressure of the Trapdoor Problem Using Three-Dimensional Discrete Element Method

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Computer Modeling in engineering & Sciences 2023年第5期135卷 1503-1520页

作者： Qizhi Chen ChuliXu Baoping Zou Zhanyou Luo Changjie Xu Xu Long school of civil engineering and architecture Zhejiang University of Science and TechnologyHangzhou310023China school of civil and Environmental engineering Ningbo UniversityNingbo315211China school of civil engineering and architecture East China Jiaotong UniversityNanchang330013China school of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi’an710072China

Load transformation from the yielding part of the soil to the adjacent part is known as the soil arching effect,which plays an important role in the design of various geotechnical infrastructures.Terzaghi’s trapdoor test was an importantmilestone in the development of theories on soil arching.The research on earth pressure of the trapdoor problem is presented in this paper using the three-dimensional(3D)discrete element method(DEM).Five 3D trapdoor models with different heights are established by 3DDEMsoftware PFC 3D.The variation of earth pressure on the trapdoor with the downward movement of the trapdoor,the distribution of vertical earth pressure along the horizontal direction,the distribution of vertical earth pressure along the vertical direction,the distribution of lateral earth pressure coefficient along the depth direction,the magnitude and direction of contact force chain are studied,respectively.Related research results show that the earth pressure on the trapdoor decreases rapidly after the downward movement of the trapdoor,and then reaches the minimum earth pressure.After that,the earth’s pressure will rise slightly,and whether this phenomenon occurs depends on the depth ratio.For the bottom soil,due to the stress transfer caused by the soil arching effect,the ratio of earth pressure in the loose area decreases,while the ratio of earth pressure in the stable area increases.With the trapdoor moving down,the vertical earth pressure along the depth in the stable zone is basically consistent with the initial state,which shows an approximate linear distribution.After the trapdoor moves down,the distribution of earth pressure along with the depth in the loose area changes,which is far less than the theoretical value of vertical earth pressure of its self-weight.Because of the compression of the soil on both sides,the lateral earth pressure coefficient of most areas on the central axis of the loose zone is close to the passive earth pressure coefficient Kp.The existence of a‘soil arch’can be observed intuiti

关键词： Soil arching effect three dimensional discrete element earth pressure contact force chain

Experimental Study on Interference Effect of Three Risers Arranged in Tandem with Variable Spacing Ratios

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china Ocean engineering 2023年第3期37卷 408-419页

作者： ZHANG Peng LIU Li-hua LIU Ming REN Xiao-hui WANG Yu school of civil engineering Qingdao University of TechnologyQingdao 266520China College of civil engineering and architecture Shandong University of Science and TechnologyQingdao 266590China Shandong Provincial Key Laboratory of civil engineering Disaster Prevention and Mitigation Qingdao 266590China school of Petroleum engineering China University of Petroleum(East China)Qingdao 266580China

Taking the three-riser group arranged in tandem as the research subject,an experimental study was carried out on the risers arranged in tandem.The purpose is to explore the sensitivity of the dynamic response of each riser to spacing ratio and reveal the physical mechanism of riser groups under the interference effect.The spacing ratios of the adj acent risers are 4.0,5.0,6.0,and 8.0.At the spacing between the risers of 4.0D,the strong feedback effect increases the cross-flow(CF) displacement amplitude of the upstream riser.The shielding effect is the key factor affecting the interference effect on the midstream and downstream risers.At low reduced velocities,the shielding area initially appears,the displacement amplitude of the midstream and downstream risers varies greatly,the vibration of the two risers is still dominated by the first-order mode,and the transition between adjacent vibration modes is restrained.The multi-frequency superposition phenomenon is very significant at high reduced velocities.The most sensitive interference spacing under the test conditions is obtained.Due to the separation of the incoming flow and the double shielding effect of the upstream and midstream risers,the regular vortex-induced vibration in the wake area of the downstream riser is broken,and the vibration in the two directions is weakened.In general,the interference effect is more significant for the CF vibration of the three-riser groups than the in-line(IL) vibration.

关键词： three-riser group tandem arrangement vortex-induced vibration wake interference variable spacing ratios

Seismic behavior of precast segmental column bridges under near-fault forward-directivity ground motions

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Earthquake engineering and engineering Vibration 2022年第2期21卷 559-571页

作者： Xin Lifeng Li Xiaozhen Fu Peiyao Mu Di school of Mechanics Civil Engineering&ArchitectureNorthwestern Polytechnical UniversityXi′an 710072China Department of Bridge engineering Southwest Jiaotong UniversityChengdu 610031China Department of civil and Environmental engineering Hanyang UniversitySeoul 04763Korea

Precast segmental column bridges exhibit various construction advantages in comparison to traditional monolithic column bridges.However,the lack of cognitions on seismic behaviors has seriously restricted their applications and developments.In this paper,comprehensive investigations are conducted to analyze the dynamic characteristics of precast segmental column bridges under near-fault,forward-directivity ground motions.First,the finite-element models of two comparable bridges with precast segmental columns and monolithic columns are constructed by using OpenSees software,and the nonlinearities of the bridges are considered.Next,three different earthquake loadings are meticulously set up to handle engineering problems,namely recorded near-and far-field ground motions,parameterized pulses,and pulse and residual components extracted from real records.Finally,based on the models and earthquake sets,extensive explorations are carried out.The results show that near-fault forward-directivity ground motions are more threatening than far-field ones;precast segmental column bridges may suffer more pounding impacts than monolithic bridges;the“narrow band”effect caused by near-fault,forward-directivity ground motions may occur in bridges with shorter periods than pulse periods;and pulse and residual components play different roles in seismic responses.

关键词： precast segmental column bridge monolithic column bridge seismic behavior near-fault forward-directivity ground motion pounding effect

Improved Geotechnical Behavior of an Expansive Soil Amended with Cationic Polyacrylamide

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Journal of Renewable Materials 2021年第11期9卷 1941-1957页

作者： Shengquan Zhou Minjie Shi Wei Chen Yongfei Zhang Weijian Wang Haojin Zhang Dongwei Li school of civil engineering and architecture Anhui University of Science and TechnologyHuainan232001China school of civil and Architectural engineering East China University of TechnologyNanchang330013China

The characteristics of soil treated with cationic polyacrylamide(CPAM)mass content of 0%,0.2%,0.4%,0.6%,0.8%,and 1%were investigated through a series of laboratory tests to explore the practical engineering effect of an expansive soil amended with environmental protection material CPAM.The results indicate that with the increasing CPAM content,the liquid limit and plasticity index of soil decrease,the plastic limit increases,and the free swelling ratio and loaded swelling ratio decrease.Besides,the improved soil has less disintegrating property and better water stability.The shear strength increases as the content increases,and the optimal content is 0.6%.Meanwhile,the cohesion of the soil first increases and then decreases,and the internal friction angle increases.Additionally,the unconfined compressive strength first increases and then decreases.The improved soil presents the characteristics of brittle failure and reaches the peak value(410.1 kPa)at the content of 0.8%after curing for 14 days.Scanning electron microscope(SEM)exhibits that the number of curved and wrinkled sections of the expansive soil is reduced after CPAM improvement.Simultaneously,the arrangement of the superimposed polymer changes from face-face to side-angle or side-face-angle,and the reticular structure formed improves the strength and spatial stability of the soil.Therefore,adding appropriate cationic polyacrylamide could improve expansive soil in engineering.

关键词： Expansive soil cationic polyacrylamide chemical modification laboratory tests microstructure

Adaptive sampling strategy for characterizing spatial distribution of soil liquefaction potential using cone penetration test

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Journal of Rock Mechanics and Geotechnical engineering 2022年第4期14卷 1221-1231页

作者： Zheng Guan Yu Wang Tengyuan Zhao Department of architecture and civil engineering City University of Hong KongTat Chee AvenueKowloonHong KongChina school of Human Settlements and civil engineering Xi’an Jiaotong UniversityXi’an710049China

Characterizing spatial distribution of soil liquefaction potential is critical for assessing liquefactionrelated hazards(e.***.building damages caused by liquefaction-induced differential settlement).However,in engineering practice,soil liquefaction potential is usually measured at limited locations in a specific site using in situ tests,e.***.cone penetration tests(CPTs),due to the restrictions of time,cost and access to subsurface space.In these cases,liquefaction potential of soil at untested locations requires to be interpreted from limited measured data points using proper interpolation method,leading to remarkable statistical uncertainty in liquefaction assessment.This underlines an important question of how to optimize the locations of CPT soundings and determine the minimum number of CPTs for achieving a target reliability level of liquefaction assessment.To tackle this issue,this study proposes a smart sampling strategy for determining the minimum number of CPTs and their optimal locations in a selfadaptive and data-driven manner.The proposed sampling strategy leverages on information entropy and Bayesian compressive sampling(BCS).Both simulated and real CPT data are used to demonstrate the proposed method.Illustrative examples indicate that the proposed method can adaptively and sequentially select the required number and optimal locations of CPTs.

关键词： Liquefaction potential Information entropy Cone penetration test(CPT) Site characterization Compressive sampling

Experimental Study on Vortex-Induced Vibration of Marine Riser Model with Coupling Interference Effect Under Combined Internal and External Flow

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中国海洋工程:英文版 2023年第4期37卷 673-684页

作者： REN Xiao-hui LI Peng CHEN Xin WANG Ye-shuo LIU Zhen HAO Lian-hong WANG Yu HUANG Yi-jie College of architecture and civil engineering Shandong University of Science and TechnologyQingdao 266590China Qingdao Key Laboratory of Marine civil engineering Materials and Structures Qingdao 266590China school of Petroleum engineering China University of Petroleum(East China)Qingdao 266580China

A partition model of interference efficiency was constructed to study the coupling interference effect under combined internal and external flow.The concept of“internal flow efficiency”,“velocity ratio”and“interference efficiency”were introduced to quantify the effect of internal flow and interference,and reveal the coupling mechanism among internal flow,external flow and interference effect.The results showed that the dynamic response of risers under variable angles was significantly different after considering the effect of internal flow.When the external flow velocity was smaller than 0.25 m/s,the vibration of risers was promoted by the internal flow.With the increase of external flow velocity,the effect of internal flow was weakened and the dynamic response of riser mainly depended on the external flow and interference effect.Under the effect of different internal flow,the interference efficiency had similar change trend.The interference effect amplified the complex secondary flow effect inside the riser,making the dynamic response of riser complex and random.In this paper,the overlap area and subdivision criterion of interference effect were constructed within the range of experimental velocity ratio,and the change curve of interference efficiency was obtained with an average meaning,which may have important practical meaning.

关键词： marine riser vortex-induced vibration internal flow interference effect interference efficiency internal flow efficiency

基于拟动力法和离散化技术的主动土压力估算方法

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Journal of Central South university 2021年第9期28卷 2890-2904页

作者：罗文俊龚琛杰王寰宇杨小礼 school of civil engineering and architecture East China Jiaotong UniversityNanchang 330013China school of civil engineering Central South UniversityChangsha 410075China

本文开展了一种拟动力法与离散化技术相结合的主动土压力计算方法的研究。采用离散化技术来生成潜在的破坏面,而不是采用预设的破坏机制,适用于土体强度参数具有空间变异性的情况。为了分析地震作用的影响,引入拟动力法考虑地震加速度... 详细信息

本文开展了一种拟动力法与离散化技术相结合的主动土压力计算方法的研究。采用离散化技术来生成潜在的破坏面,而不是采用预设的破坏机制,适用于土体强度参数具有空间变异性的情况。为了分析地震作用的影响,引入拟动力法考虑地震加速度动力特性的地震力。采用一种新型的微单元来计算外力的做功速率和内部能量的耗散速率。利用上界定理推导了地震主动土压力系数的解析表达式,并通过数值优化得到了相应的上界解。通过与文献结果的比较,验证了本文方法的有效性。通过参数分析,进一步阐述了不同参数对非均匀土作用下主动土压力的影响。

关键词：拟动力法离散元技术上限分析不均匀性地震主动土压力系数