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Water-induced physicochemical and pore changes in limestone for surrounding rock across pressure aquifers

Journal of Mountain Science 2024年第9期21卷 3186-3200页

作者： WU daguo PENG Jianhe XIA Zhenzhao School of civil and hydraulic engineering Hefei University of TechnologyHefei 230009China Anhui and Huaihe River Institute of hydraulic Research Hefei 230088China School of civil and hydraulic engineering Huazhong University of Science and TechnologyWuhan 430074China

Osmotic water alters the physicochemical properties and internal structures of *** issue is particularly critical in tunnel construction across mountainous regions with aquifers,where pressurized groundwater can destabilize the limestone-based surrounding ***,systematic research into the physicochemical properties and pore structure changes in the limestone under pressurized water is ***,it is essential to develop an interpretable mathematical model to accurately depict how pressurized osmotic water weakens *** this research,a specialized device was designed to simulate the process of osmotic laminar flow within ***,four main tests were conducted:mass loss,acoustic emission(AE),mercury intrusion porosimetry(MIP),and fluorescence *** results gained from tests led to the development of a“Particle-pore throat-water film”*** model explains water-induced physicochemical and pore changes in limestone under osmotic pressure and reveals evolutionary mechanisms as pressure *** on experimental results and model,we found that osmotic pressure not only alters limestone composition but also affects pore throats larger than 0.1μ***,osmotic pressure expands pore throats,enhancing pore structure uniformity,interconnectivity,and *** effects are observed at a threshold of 7.5 MPa,where cohesive forces within the mineral lattice are surpassed,leading to the breakdown of erosion-resistant layer and a significant increase in hydrochemical erosion.

关键词： Water rock reaction Geochemistry Osmotic pressure Pore scale study Limestone Pressure aquifer

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Time-dependent deviation of bridge pile foundations caused by adjacent large-area surcharge loads in soft soils and its preventive measures

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Frontiers of Structural and civil engineering 2024年第2期18卷 184-201页

作者： Shuanglong LI Limin WEI Jingtai NIU Zhiping dENG Bangbin WU Wuwen QIAN Feifei HE School of hydraulic engineering Nanchang Institute of TechnologyNanchang 330099China School of civil engineering Central South UniversityChangsha 410075China

Time-dependent characteristics(TdCs)have been neglected in most previous studies investigating the deviation mechanisms of bridge pile foundations and evaluating the effectiveness of preventive *** this study,the stress-strain-time characteristics of soft soils were illustrated by consolidation-creep tests based on a typical engineering *** extended Koppejan model was developed and then embedded in a finite element(FE)model via a user-material subroutine(UMAT).Based on the validated FE model,the time-dependent deformation mechanism of the pile foundation was revealed,and the preventive effect of applying micropiles and stress-release holes to control the deviation was *** results show that the calculated maximum lateral displacement of the cap differs from the measured one by 6.5%,indicating that the derived extended Koppejan model reproduced the deviation process of the bridge cap-pile foundation with *** additional load acting on the pile side caused by soil lateral deformation was mainly concentrated within the soft soil layer and increased with the increase in load *** with t=3 d(where t is surcharge time),the maximum lateral additional pressure acting on Pile 2#increased by approximately 47.0%at t=224 *** bridge pile foundation deviation in deep soft soils,stress-release holes can provide better prevention compared to micropiles and are therefore recommended.

关键词： bridge pile foundation surcharge load soft soil time-dependent deformation interaction mechanism preventive measure

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Water-induced physicochemical and pore changes in limestone for surrounding rock across pressure aquifers

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Journal of Mountain Science 2024年第09期 3186-3200页

作者： WU daguo PENG Jianhe XIA Zhenzhao School of civil and hydraulic engineering Hefei University of Technology Anhui and Huaihe River Institute of hydraulic Research School of civil and hydraulic engineering Huazhong University of Science and Technology

Osmotic water alters the physicochemical properties and internal structures of limestone. This issue is particularly critical in tunnel construction across mountainous regions with aquifers, where pressurized groundwater can destabilize the limestone-based surrounding rock. Thus, systematic research into the physicochemical properties and pore structure changes in the limestone under pressurized water is essential. Additionally, it is essential to develop an interpretable mathematical model to accurately depict how pressurized osmotic water weakens limestone. In this research, a specialized device was designed to simulate the process of osmotic laminar flow within limestone. Then, four main tests were conducted: mass loss, acoustic emission(AE), mercury intrusion porosimetry(MIP), and fluorescence analysis. Experimental results gained from tests led to the development of a “Particle-pore throat-water film” model. Proposed model explains water-induced physicochemical and pore changes in limestone under osmotic pressure and reveals evolutionary mechanisms as pressure increases. Based on experimental results and model, we found that osmotic pressure not only alters limestone composition but also affects pore throats larger than 0.1 μm. Furthermore, osmotic pressure expands pore throats, enhancing pore structure uniformity, interconnectivity, and permeability. These effects are observed at a threshold of 7.5 MPa, where cohesive forces within the mineral lattice are surpassed, leading to the breakdown of erosion-resistant layer and a significant increase in hydrochemical erosion.

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At-rest lateral earth pressure of compacted expansive soils:Experimental investigations and prediction approach

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Journal of Rock Mechanics and Geotechnical engineering 2024年第4期16卷 1425-1435页

作者： Zhong Han Pan Zhang Weilie Zou Kewei Fan Sai K.Vanapalli Lianglong Wan School of civil engineering Wuhan UniversityWuhanChina Key Laboratory of Rock Mechanics in hydraulic Structural engineering of the Ministry of Education Wuhan UniversityWuhanChina department of civil engineering University of OttawaOttawaOntarioCanada Key Laboratory of Ministry of Education for Geomechanics and Embankment engineering Hohai UniversityNanjingChina Residence engineering Management Station of Shenzhen Municipality ShenzhenChina

This paper presents experimental studies on a compacted expansive soil,from Nanyang,China for investigating the at-rest lateral earth pressureσL of expansive *** key studies include(i)relationships between theσL and the vertical stressσV during soaking and consolidation,(ii)the influences of initial dry densityρd0 and moisture content w 0 on the vertical and lateral swelling pressures at no swelling strain(i.e.σV0 andσL0),and(iii)evolution of theσL during five long-term wetting-drying *** results demonstrated that the post-soakingσL-σV relationships are piecewise linear and their slopes in the passive state(σL>σV)and active state(σLdationσL-σV relationships in the normal-and over-consolidated states,*** soakingσL-σV relationships converge to the consolidationσL-σV relationships at a thresholdσV where the interparticle swelling is ***σL0 andσV0 increase monotonically withρd0;however,they show increasing-then-decreasing trends with the w *** extent of compaction-induced swelling anisotropy,which is evaluated byσL0/σV0,reduces with an increase in the compaction energy and molding water ***σL reduces over moisture cycles and the stress relaxation in theσL during soaking is *** approach was developed to predict the at-rest soakingσL-σV relationships,which requires conventional consolidation and shear strength properties and one measurement of theσL-σV relationships during *** proposed approach was validated using the results of three different expansive soils available in the literature.

关键词： Lateral earth pressure Expansive soil Soaking Vertical stress Swelling pressure

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A new weir surface repair layer with shock absorbing cushion design

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Earthquake engineering and engineering Vibration 2013年第3期12卷 487-496页

作者： Tse-Shan Hsu Yi-Lang Hsieh department of civil engineering Feng-Chia University ph.d program in civil and hydraulic engineering Feng-Chia University

A shock absorbing cushion has never been introduced into any traditional weir surface repair layer design. However, shocks induced by high discharge with heavy sediment can easily produce brittle fracture and peeling over a weir surthce repair layer as it is impacted by floods accompanied by particles of different sizes. In this study, transcending traditional designs, the authors developed a composite unit designed with a shock absorbing cushion that has performed well during field tests, proving that the weir body can be effectively protected even if the composite units are directly laid on a severely uneven weir surface repair layer.

关键词： shock absorbing cushion brittle fracture peeling weir

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Effect of coral sand on the mechanical properties and hydration mechanism of magnesium potassium phosphate cement mortar

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Journal of Zhejiang University-Science A(Applied physics & engineering) 2024年第2期25卷 116-129页

作者： Hao LIU Huamei YANG Houzhen WEI Jining YU Qingshan MENG Rongtao YAN College of civil engineering and Architecture Guilin University of TechnologyGuilin541004China Guangxi Key Laboratory of Geomechanics and Geotechnical engineering Guilin University of TechnologyGuilin541004China State Key Laboratory of Geomechanics and Geotechnical engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China School of Intelligent Construction Wuchang University of TechnologyWuhan430002China hydraulic Concrete Institute China Three Gorges CorporationBeijing100038China The First Railway Survey and design Institute Group Corporation Xi’an710043China

damaged structures on coral islands have been spalling and cracking due to the dual corrosion of tides and *** ensure easy access to aggregate materials,magnesium potassium phosphate cement(MKPC)and coral sand(CS)are mixed to repair damaged structures on coral ***,CS is significantly different from land-sourced sand in mineral composition,particle morphology,and *** has a substantial impact on the hydration characteristics and macroscopic properties of MKPC ***,in this study we investigated the compressive strength,interfacial mechanical properties,and corrosion resistance of MKPC CS *** in the morphology,microstructure,and relative contents of hydration products were revealed by scanning electron microscope-energy dispersive spectrometer(SEM-EdS)and X-ray diffraction(XRd).The results indicated that the compressive strength increased linearly with the interfacial micro-hardness,and then stabilized after long-term immersion in pure water and Na2SO4 solution,showing excellent corrosion *** with MKPC river sand(RS)mortar,the hydration products of CS mortar were an intermediate product 6KPO2·8H2O with a relative content of 3.9%at 1 h and 4.1%at 12 *** hydration product MgKPO_(4)·6H_(2)O increased rapidly after 7-d curing,with an increased growth rate of 1100%.Our results showed that CS promoted the nucleation and formation of hydration products of MKPC,resulting in better crystallinity,tighter overlapping,and a denser interfacial transition *** results of this study provide technical support for applying MKPC mortar as a rapid repair material for damaged structures on coral islands.

关键词： Magnesium potassium phosphate cement(MKPC) Coral sand(CS) Mechanical properties Corrosion resistance Hydration mechanism

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Numerical Analysis of Perforation during hydraulic Fracture Initiation Based on Continuous-discontinuous Element Method

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Computer Modeling in engineering & Sciences 2024年第8期140卷 2103-2129页

作者： Rui Zhang Lixiang Wang Jing Li Chun Feng Yiming Zhang School of civil and Transportation engineering Hebei University of TechnologyTianjin300401China Key Laboratory for Mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing100190China School of civil engineering and Architecture Zhejiang Sci-Tech UniversityHangzhou310018China Jinyun Institute Zhejiang Sci-Tech UniversityLishui321400China

Perforation is a pivotal technique employed to establish main flow channels within the reservoir formation at the outset of hydraulic fracturing *** perforation designs is critical for augmenting the efficacy of hydraulic fracturing and boosting oil or gas *** this study,we employ a hybrid finite-discrete element method,known as the continuous–discontinuous element method(CdEM),to simulate the initiation of post-perforation hydraulic fractures and to derive enhanced design *** model incorporates the four most prevalent perforation geometries,as delineated in an engineering technical ***-world perforations deviate from the ideal cylindrical shape,exhibiting variable cross-sectional profiles that typically manifest as an initial constriction followed by an expansion,a feature consistent across all four perforation *** simulations take into account variations in perforation hole geometries,cross-sectional diameters,and perforation *** findings show that perforations generated by the 39g dP3 HMX perforating bullet yield the lowest breakdown pressure,which inversely correlates with increases in sectional diameter and perforation ***,this study reveals the relationship between breakdown pressure and fracture degree,providing valuable insights for engineers and designers to refine perforation strategies.

关键词： hydraulic fracturing real perforation shape breakdown pressure perforation layout design CdEM

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Seismic performance of an existing bridge with scoured caisson foundation

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Earthquake engineering and engineering Vibration 2014年第S1期13卷 151-165页

作者： Kuo-Chun Chang Yu-Chi Sung Kuang-Yen Liu Ping-Hsiung Wang Zheng-Kuan Lee Lu-Sheng Lee Witarto department of civil engineering Taiwan University (NTU) Professor department of civil engineering Taipei University of Technology (NTUT) Center for Research on Earthquake engineering (NCREE) Associate Researcher Associate Technologist Technologist department of civil engineering The University of Houston ph.d Student

This paper presents in-situ seismic performance tests of a bridge before its demolition due to accumulated scouring problem. The tests were conducted on three single columns and one caisson-type foundation. The three single columns were 1.8 m in diameter,reinforced by 30-d32 longitudinal reinforcements and laterally hooped by d16 reinforcements with spacing of 20 cm. The column height is 9.54 m,10.59 m and 10.37 m for Column P2,P3,and P4,respectively. Column P2 had no exposed foundation and was subjected to pseudo-dynamic tests with peak ground acceleration of 0.32 g first,followed by one cyclic loading test. Column P3 was the benchmark specimen with exposed length of 1.2 m on its foundation. The exposed length for Column P4 was excavated to 4 m,approximately 1/3 of the foundation length,to study the effect of the scouring problem to the column performance. Both Column P3 and Column P4 were subjected to cyclic loading tests. Based on the test results,due to the large dimension of the caisson foundation and the well graded gravel soil type that provided large lateral resistance,the seismic performance among the three columns had only minor differences. Lateral push tests were also conducted on the caisson foundation at Column P5. The caisson was 12 m long and had circular cross-sections whose diameters were 5 m in the upper portion and 4 m in the lower portion. An analytical model to simulate the test results was developed in the OpenSees platform. The analytical model comprised nonlinear flexural elements as well as nonlinear soil springs. The analytical results closely followed the experimental test results. A parametric study to predict the behavior of the bridge column with different ground motions and different levels of scouring on the foundation are also discussed.

关键词： Analytical models Cyclic loads hydraulic structures Piles Pressure vessels Reinforcement Seismic waves Seismology Soil structure interactions Soils Textile scouring Underwater foundations

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Using NH_(2)-MIL-125(Ti)for efficient removal of Cr(Ⅵ)and Rh B from aqueous solutions:Competitive and cooperative behavior in the binary system

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Journal of Environmental Sciences 2024年第2期136卷 437-450页

作者： Lei Zheng Lixia Sun Jiangbo Qiu Junling Song Luyi Zou Yue Teng Yongzhong Zong Hongyan Yu School of Environmental and civil engineering Jiangnan UniversityWuxi 214122China School of Chemical and Material engineering Jiangnan UniversityWuxi 214122China Kunming South Water Co. Ltd.Kunming 650501China Jiangsu Key Laboratory of Anaerobic Biotechnology Jiangnan UniversityWuxi 214122China

The coexistence of inorganic and organic contaminants is a challenge for real-life water treatment ***,in this research,we used NH_2-MIL-125(Ti)to evaluate the single adsorption of hexavalent chromium(Cr(Ⅵ))or Rhodamine B(RhB)in an aqueous solution and further investigate simultaneous adsorption experiments to compare the adsorption behavior *** main influencing factors,for example,reaction time,initial concentration,reaction temperature,and ph were studied in *** all reaction systems,the pseudo-second-order kinetic and Langmuir isotherm models were well illuminated the adsorption progress of Cr(Ⅵ)and *** studies showed that the adsorption process was spontaneous and *** compared to the single system,the adsorption capacity of Cr(Ⅵ)in the binary system gradually decreased as the additive amount of RhB increased,whereas the adsorption capacity of RhB in the binary system was expanded *** the binary reaction system contained 100 mg/L Cr(Ⅵ),the removal rate of RhB increased to 97.58%.The formation of Cr(Ⅵ)-RhB and Cr(Ⅲ)-RhB complexes was the cause that provided facilitation for the adsorption of *** findings prove that the interactions during the water treatment process between contaminants may obtain additional benefits,contributing to a better adsorption capacity of co-existing contaminant.

关键词： Adsorption Heavy metal ion Organic dye Simultaneous removal Mechanism studies

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development of MoS_(2)-stainless steel catalyst by 3d printing for efficient destruction of organics via peroxymonosulfate activation

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Journal of Environmental Sciences 2024年第1期135卷 108-117页

作者： Yufeng Liu Jianhui Xu Xin Fu Pengxu Wang dan Li Yunfei Zhang Shenggui Chen Chunhui Zhang Peng Liu School of Environment and civil engineering Dongguan University of TechnologyDongguan 523808China School of Art and design Guangzhou Panyu PolytechnicGuangzhou 511483China dongguan Institute of Science and Technology Innovation Dongguan University of TechnologyDongguan 523808China School of Mechanical engineering Dongguan University of TechnologyDongguan 523808China

Herein,a novel MoS_(2)-stainless steel composite material was first synthetized via a 3d printing method(3dP MoS_(2)-SS)for peroxymonosulfate(PMS)activation and organics *** with MoS_(2)-SS powder/PMS system(0.37 g/(m^(2)/min)),4.3-fold higher k_(FLO)/S_(BET)value was obtained in 3dP MoS_(2)-SS/PMS system(1.60 g/(m^(2)/min),resulting from the superior utilization of active *** observed that 3dP MoS_(2)-SS significantly outperformed the 3dP SS due to the enhanced electron transfer rate and increased active ***,Mo^(4+)facilitated the Fe^(2+)/Fe^(3+)cycle,resulting in the rapid degradation of florfenicol(FLO).Quenching experiments and electron paramagnetic resonance spectra indicated that·OH,SO_(4)·^(-),O_(2)·^(-)and^(1)O_(2)were involved in the degradation of *** effect of influencing factors on the degradation of FLO were evaluated,and the optimized degradation efficiency of 98.69%was achieved at 1 mM PMS and ph of *** degradation products were detected by UPLC/MS analyses and several possible degradation pathways were proposed to be the cleavage of C-N bonds,dechlorination,hydrolysis,defluorination and *** addition,3dP MoS_(2)-SS/PMS system also demonstrated superior degradation performance for 2-chlorophenol,acetaminophen,ibuprofen and *** study provided deep insights into the MoS_(2)-SS catalyst prepared by 3dP technology for PMS activation and FLO-polluted water treatment.

关键词： 3d printing Stainless steel MoS_(2) Peroxymonosulfate activation degradation mechanism

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