This issue covers the papers on two special themes:(1)Mineral resources from deep sea—Science and Engineering and(2)Planning and development of underground space and infrastructure for sustainable and liveable cities.
Strainbursts induced by cyclic disturbance with low frequency(termed as cyclicinduced strainbursts)are major dynamic disasters during deep excavation and mining.There is currently no quantitative criterion available f...Strainbursts induced by cyclic disturbance with low frequency(termed as cyclicinduced strainbursts)are major dynamic disasters during deep excavation and mining.There is currently no quantitative criterion available for the prediction of such disastrous events.In this study,based on true triaxial experiments,we analyzed the deformation characteristics,established two novel strain criteria for the cyclic-induced strainbursts,and explained the physical meaning of these criteria.Characteristic strains for the cyclic-induced strainbursts were defined,including the control strain ε_(ctr),the strain caused by the combined dynamic and static loading ε_(sd),and the ultimate strain ε_(u) after strainbursts.As indicated by the results,the deformation evolution of the cyclic-induced strainbursts shows remarkable fatigue characteristics,which resemble that of rock subjected to cyclic loading and unloading.In other words,there are three stages during deformation evolution,namely,initial rapid growth,uniform velocity growth after several periods of disturbance,and sudden sharp growth preceding the burst.The ultimate strain ε_(u) is insensitive to the tangential static stress and disturbance amplitude,but it changes nonlinearly with disturbance frequency.From the perspective of deformation,the occurrence of a cyclic-induced strainburst is controlled by the control strainε_(ctr).Thus,a control strain criterion is proposed;that is,when the stain ε_(sd) is larger than the control strain ε_(ctr),a strainburst will be induced by cyclic disturbance.Moreover,based on the statistical results,a strain ratio criterion is proposed;that is,when the strain ratio ε_(sd)/ε_(u) is greater than 30%,a cyclic-induced strainburst will be induced.展开更多
With the increasing scarcity of shallow resources,the mining depth of coal mines has gradually increased,and the safety problem has become increasingly prominent.The grouting technology for deep roadways in fractured ...With the increasing scarcity of shallow resources,the mining depth of coal mines has gradually increased,and the safety problem has become increasingly prominent.The grouting technology for deep roadways in fractured rocks is one of key technologies for safe mining of deep resources.This paper by the team of Hongpu Kang,academician of the Chinese Academy of Engineering,systematically summarizes and analyzes the research findings in the theory,design,materials,processes,and equipment for the grouting reinforcement of fractured rocks surrounding the deep roadways.Several field cases in the Kouzidong coal mine are demonstrated on the application of pregrouting in front of heading faces,grouting in excavation,and postgrouting so as to evaluate the effects of these grouting reinforcements.展开更多
Deep Underground Science and Engineering(DUSE)publishes this special issue on geothermal energy.The guest editors of this special issue are Prof.Ranjith Pathegama Gamage(Monash University,Australia),Prof.Zhongwei Huan...Deep Underground Science and Engineering(DUSE)publishes this special issue on geothermal energy.The guest editors of this special issue are Prof.Ranjith Pathegama Gamage(Monash University,Australia),Prof.Zhongwei Huang(China University of Petroleum,Beijing,China),and Prof.Bing Bai(Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,China).Geothermal energy is one sustainable and renewable energy and currently a hot research topic in research and development.Geothermal energy supply is one of the long-term efforts for carbon footprint reductions to tackle climate change issues.The development of geothermal energy includes exploration and extraction processes.This special issue is to highlight the challenges on the exploration and extraction of geothermal energy such as initial high cost and difficulties in heat extraction from deep underground.This special issue focuses on new geothermal extraction system,new theory,new technology,new application of latest techniques such as artificial intelligence,and potential environmental effects.展开更多
This paper studies the microstructure variation induced by super-absorbent polymer(SAP)to understand the mechanism of macroscopic strength improvement of stabilized soil.The fabric changes of cement elime stabilized s...This paper studies the microstructure variation induced by super-absorbent polymer(SAP)to understand the mechanism of macroscopic strength improvement of stabilized soil.The fabric changes of cement elime stabilized soil were analyzed with respect to the variation of SAP content,water content,lime content and curing time,using mercury intrusion porosimetry(MIP)tests.It can be observed that the delimitation pore diameter between inter-and intra-aggregate pores was 0.2 mm for the studied soil,determined through the intrusion/extrusion cycles.Experimental results showed that fabric in both inter-and intra-aggregate pores varied significantly with SAP content,lime content,water content and curing time.Two main changes in fabric due to SAP are identified as:(1)an increase in intra-aggregate pores(<0.2 mm)due to the closer soilecementelime cluster space at higher SAP content;and(2)a decrease in inter-aggregate pores represented by a reduction in small-pores(0.2e2 mm)due to the lower pore volume of soil mixture after water absorption by SAP,and a slight increase in large-pores(>2 mm)due to the shrinkage of SAP particle during the freezeedry process of MIP test.Accordingly,the strength gain due to SAP for cementelime stabilized soil was mainly due to a denser fabric with less interaggregate pores.The cementitious products gradually developed over time,leading to an increase in intra-aggregate pores with an increasing proportion of micro-pores(0.006e0.2 mm).Meanwhile,the inter-aggregate pores were filled by cementitious products,resulting in a decrease in total void ratio.Hence,the strength development over time is attributable to the enhancement of cementation bonding and the refinement of fabric due to the increasing cementitious compounds.展开更多
In deep-earth engineering,the high earth temperature can significantly affect the rock's mechanical properties,especially when the rock is cooled during the construction process.Accordingly,whether the cooling spe...In deep-earth engineering,the high earth temperature can significantly affect the rock's mechanical properties,especially when the rock is cooled during the construction process.Accordingly,whether the cooling speed affects the mechanical and physical properties of rocks is worth to be investigated.The present study explored the influence of the cooling rate on the physical and chemical properties of granite heated at 25–800°C.The mechanical and physical properties involved in this study included uniaxial compression strength,peak strain,modulus,P-wave velocity,mass and volume,the change of which could reflect the sensitivity of granite to the cooling rate.Acoustic emission(AE)monitoring,microscopic observation,and X-ray diffraction(XRD)are used to analyze the underlying damage mechanism.It is found that more AE signals and large-scale cracks are accounted for based on the b-value method when the specimens are cooled by water.Furthermore,the microscopic observation by polarized light microscopy indicates that the density,opening degree,and connectivity of the cracks under water cooling mode are higher than that under natural cooling mode.In addition,the XRD illustrates that there is no obvious change in mineral content and diffraction angle at different temperatures,which confirms that the change of mechanical properties is not related to the chemical properties.The present conclusion can provide a perspective to assess the damage caused by different cooling methods to hot rocks.展开更多
Myeloperoxidase antineutrophil cytoplasmic antibody(MPO-ANCA)associated vasculitis is an autoimmune disease usually with severe multiple dysfunction syndrome,especially prominent acute renal failure.A 65-year-old woma...Myeloperoxidase antineutrophil cytoplasmic antibody(MPO-ANCA)associated vasculitis is an autoimmune disease usually with severe multiple dysfunction syndrome,especially prominent acute renal failure.A 65-year-old woman was admitted with progressive dyspnoea for six months and fever,sputum with blood,pain of the lower extremities and intermittent claudication for two days,indicating multiple organ involvement(respiratory system,blood vessels).The renal involvement was relatively mild,presenting with microscopic haematuria.The chest computed tomography demonstrated multiple pulmonary embolisms.Ultrasound and computed tomography angiography for the lower extremity vessels showed venous and arterial thrombosis.Exclusion of other diseases that can cause multiple organ damage and thrombosis,the positive perinuclear ANCA and MPO-ANCA strongly support the diagnosis of MPO-ANAC-associated vasculitis.The patient’s physical condition has been greatly improved by treatment with corticosteroids and anticoagulation.展开更多
Renal amyloidosis secondary to anti-neutrophil cytoplasmic antibody(ANCA)-associated vasculitis is extremely rare.Here,we reported a 77-year-old woman with ANCA-associated vasculitis.Renal biopsy with Masson trichrome...Renal amyloidosis secondary to anti-neutrophil cytoplasmic antibody(ANCA)-associated vasculitis is extremely rare.Here,we reported a 77-year-old woman with ANCA-associated vasculitis.Renal biopsy with Masson trichrome staining showed pauci-immune crescentic glomerulonephritis,and electron microscopy showed amyloid deposition in the mesangial area.Immunofluorescence revealed kappa light chain and lambda light chain negative.Bone marrow biopsy revealed no clonal plasma cell.Finally,she was diagnosed as ANCA-associated vasculitis with secondary renal amyloid A amyloidosis.展开更多
The effect of intermediate stress(in situ tunnel axial)on a strainburst is studied with a threedimensional(3D)bonded block distinct element method(DEM).A series of simulations of strainbursts under true triaxial in si...The effect of intermediate stress(in situ tunnel axial)on a strainburst is studied with a threedimensional(3D)bonded block distinct element method(DEM).A series of simulations of strainbursts under true triaxial in situ stress conditions(i.e.high tangential stress,moderate intermediate stress and low radial stress)of near-boundary rock masses are performed.Compared with the experimental results,the DEM model is able to capture the stress-strain response,failure pattern and energy balance of strainbursts.The fracturing processes of strainbursts are also numerically reproduced.Numerical results show that,as the intermediate stress increases:(1)The peak strain of strainbursts increases,the yield stress increases,the rock strength increases linearly,and the ratio of yield stress to rock strength decreases,indicating that the precursory information on strainbursts is enhanced;(2)Tensile and shear cracks increase significantly,and slabbing and bending of rock plates are more pronounced;and(3)The stored elastic strain energy and dissipated energy increase linearly,whereas the kinetic energy of the ejected rock fragments increases approximately exponentially,implying an increase in strainburst intensity.By comparing the experimental and numerical results,the effect of intermediate stress on the rock strength of strainbursts is discussed in order to address three key issues.Then,the Mogi criterion is applied to construct new strength criteria for strainbursts by converting the one-face free true triaxial stress state of a strainburst to its equivalent true triaxial stress state.In summary,the effect of intermediate stress on strainbursts is a double-edged sword that can enhance the rock strength and the precursory information of a strainburst,but also increase its intensity.展开更多
This paper presents a regional 3D geological modeling method based on the stacking ensemble technique to overcome the challenges of sparse borehole data in large-scale linear underground projects.The proposed method t...This paper presents a regional 3D geological modeling method based on the stacking ensemble technique to overcome the challenges of sparse borehole data in large-scale linear underground projects.The proposed method transforms the 3D geological modeling problem into a stratigraphic property classification problem within a subsurface space grid cell framework.Borehole data is pre-processed and trained using stacking method with five different machine learning algorithms.The resulting modelled regional cells are then classified,forming a regional 3D grid geological model.A case study for an area of 324 km2 along Xuzhou metro lines is presented to demonstrate the effectiveness of the proposed model.The study shows an overall prediction accuracy of 85.4%.However,the accuracy for key stratigraphy layers influencing the construction risk,such as karst carve strata,is only 4.3%due to the limited borehole data.To address this issue,an oversampling technique based on the synthetic minority oversampling technique(SMOTE)algorithm is proposed.This technique effectively increases the number of sparse stratigraphic samples and significantly improves the prediction accuracy for karst caves to 65.4%.Additionally,this study analyzes the impact of sampling distance on model accuracy.It is found that a lower sampling interval results in higher prediction accuracy,but also increases computational resources and time costs.Therefore,in this study,an optimal sampling distance of 1 m is chosen to balance prediction accuracy and computation cost.Furthermore,the number of geological strata is found to have a negative effect on prediction accuracy.To mitigate this,it is recommended to merge less significant stratigraphy layers,reducing computation time.For key strata layers,such as karst caves,which have a significant impact on construction risk,further onsite sampling or oversampling using the SMOTE technique is recommended.展开更多
The editors wish to highlight the articles appearing in this issue.The first article,entitled“New physics of supersonic ruptures”by Boris G.Tarasov,concerns the development of a new theory on the potential occurrenc...The editors wish to highlight the articles appearing in this issue.The first article,entitled“New physics of supersonic ruptures”by Boris G.Tarasov,concerns the development of a new theory on the potential occurrence of ruptures after deep underground earthquakes.Two other articles belong to our first special theme of“Disaster evolution in deep underground.”The final two articles introduce a nonlocal damage fracture phasefield model for rock‐like materials and the gas–liquid displacement in microcleats for mass transfer through gas‐or water‐driven displacement.These five papers indeed explore various aspects of deep underground science and engineering and constitute an integral component of deep underground fundamentals.展开更多
We highlight two articles in this issue:A research article titled“Excavation compensation theory and supplementary technology system for large deformation disasters”by Manchao He et al.and a review article titled“M...We highlight two articles in this issue:A research article titled“Excavation compensation theory and supplementary technology system for large deformation disasters”by Manchao He et al.and a review article titled“Mineralogy,microstructures and geomechanics of rock salt for underground gas storage”by Veerle Vandeginste et al.展开更多
To the Editor:Allergic bronchopulmonary aspergillosis(ABPA)is an allergic lung disease caused by hypersensitivity to antigens from Aspergillus,and it most commonly occurs in patients with asthma or cysticbrosis.[1]The...To the Editor:Allergic bronchopulmonary aspergillosis(ABPA)is an allergic lung disease caused by hypersensitivity to antigens from Aspergillus,and it most commonly occurs in patients with asthma or cysticbrosis.[1]The main clinical characteristics of the disease are those related to elevated serum immunoglubulin(Ig)E level,positive Aspergillus fumigatus(A.fumigatus)specic IgE/IgG,repeated pulmonary inltration,and bronchiectasis.However,due to the lack of unied diagnostic criteria and screening methods,ABPA is always underdiagnosed.In 2021,new diagnostic criteria were proposed for allergic bronchopulmonary mycosis(ABPM)in the Japanese population.展开更多
This study aims at proposing a reasonable roughness parameter that can reflect the peak shear strength(PSS)of rock joints.Firstly,the contribution of the asperities with different apparent dip angles to shear strength...This study aims at proposing a reasonable roughness parameter that can reflect the peak shear strength(PSS)of rock joints.Firstly,the contribution of the asperities with different apparent dip angles to shear strength is studied.Then the shear strength of the entire joint asperities is derived.The results showed that the PSS of the entire joint asperities is proportional to a key parameter hs,which is related to the geometric character of the joint surface and the joint material properties.The parameter hsis taken as the new roughness parameter,and it is reasonable to associate the PSS with the geometric characteristics of the joint surface.Based on the new roughness parameter and shear test results of 20 sets of joint specimens,a new PSS model for rock joints is proposed.The new model is validated with the artificial joints in this paper and real rock joints in published studies.Results showed that it is suitable for different types of rock joints except for gneiss joints.The new model has the form of the Mohr-Coulomb model,which can directly reflect the relationship between the 3 D roughness parameters and the peak dilation angle.展开更多
The sealing performance of a bentonite barrier is highly dependent on its seepage characteristics, which are directly related to the characteristics of its pore structure. Based on scanning electron microscopy(SEM) an...The sealing performance of a bentonite barrier is highly dependent on its seepage characteristics, which are directly related to the characteristics of its pore structure. Based on scanning electron microscopy(SEM) and focused ion beam-SEM(FIB-SEM), the pore structure of bentonite was characterized at different scales. First, a reasonable gray threshold was determined through back analysis, and the image was binarized based on the threshold. In addition, binary images were used to analyze bentonite’s pore structure(porosity and pore size distribution). Furthermore, the effects of different algorithms on the pore structure characterization were evaluated. Then, permeability calculations were performed based on the previous pore structure characteristics and a modified permeability prediction model. For permeability prediction based on the three-dimensional model, the effect of pore tortuosity was also considered. Finally, the accuracy of numerical calculations was verified by conducting macroscopic gas and alcohol permeability experiments. This approach provides a better understanding of the microscale mechanism of gas transport in bentonite and the importance of pore structures at different scales in determining its seepage characteristics.展开更多
Deep underground provides enormous resources for mankind,such as energy,minerals,and water.It can also provide effective solutions for pollutant disposal,such as nuclear waste disposal and CO_(2) geosequestration,as w...Deep underground provides enormous resources for mankind,such as energy,minerals,and water.It can also provide effective solutions for pollutant disposal,such as nuclear waste disposal and CO_(2) geosequestration,as well as storage spaces.In addition,deep underground is of great necessity because it provides an ultra-quiet environment for scientific research facilities for advanced experiments in physics,chemistry,and medicine.展开更多
This paper introduces the establishment of deep underground infrastructure for science and engineering research.First,the representative deep underground research laboratories and facilities in the world and their fun...This paper introduces the establishment of deep underground infrastructure for science and engineering research.First,the representative deep underground research laboratories and facilities in the world and their functions were summarized and reviewed.Then,the plan and service target of China Yulong Lake Laboratory were proposed for the storage of resources and energy,as well as the sealing of hazardous waste in deep underground space.On this basis,this paper reveals how the facility addresses its key scientific issue on“The law of fluid matter migration in deep underground space”and engineering significance.Finally,the construction progress of the facility components was demonstrated in details.As is hoped,this paper would provide useful reference to the deep underground research community;meanwhile,international collaboration on deep underground research is highly welcome.展开更多
In this paper,how to determine the Weibull modulus of a fracture strength distribution is discussed with its physical implications for quasi-brittle materials.Based on the Markov chain assumption,it is shown that the ...In this paper,how to determine the Weibull modulus of a fracture strength distribution is discussed with its physical implications for quasi-brittle materials.Based on the Markov chain assumption,it is shown that the lifetime(i.e.,the time taken for formation of a critical defect)in a quasi-brittle material can be described by a gamma probabilistic distribution function.Prior to macroscopic failure,the effective number of energy barriers to be overcome is determined by the slope of the energy barrier spectrum,which is equivalent to the Weibull modulus.Based on a fracture mechanics model,the fracture energy barrier spectral slope and Weibull modulus can be calculated theoretically.Furthermore,such a model can be extended to take into account the crack interactions and defect-induced degradation.The predicted Weibull modulus is good agreement with that derived from available experimental results.展开更多
The tensile creep fracture behaviors in brittle solids are of great significance for the safety evaluation of brittle solid engineering.However,micromechanics-based tensile creep fracture behavior is rarely studied.In...The tensile creep fracture behaviors in brittle solids are of great significance for the safety evaluation of brittle solid engineering.However,micromechanics-based tensile creep fracture behavior is rarely studied.In this study,a micromechanics-based method for predicting direct tensile creep fractures is presented.This method is established by combining the suggested expression of the mode-I stress intensity factor,the subcritical crack growth law,and the relationship between wing crack length and axial strain.This suggested mode-I stress intensity factor is formulated by the use of the basic theory of fracture mechanics under different loading modes.The rationality of the proposed tensile creep fracture model is verified by comparing with the experimental results.The correspondences of time-dependent axial strain,strain rate,wing crack length,and crack velocity are plotted under constant stress and stepping stress during tensile creep fracture.The effects of the initial crack size,inclination angle and density on the crack initiation stress,tensile strength,tensile creep fracture time,steady-state strain rate,initial strain,crack coalescence strain,and failure strain are discussed.展开更多
Four types of granite specimens were prepared and treated by chemical corrosion for 5 and 30 days,which were then used to carry out triaxial compression tests under different confining pressuresσ_(3).Type A is the in...Four types of granite specimens were prepared and treated by chemical corrosion for 5 and 30 days,which were then used to carry out triaxial compression tests under different confining pressuresσ_(3).Type A is the intact sample with no preexisting flaws.Types B and C are the samples containing two relatively low-dip flaws and two relatively high-dip flaws,respectively.Type D is the sample including both relatively low-dip and relatively high-dip flaws.The influences of pH value of chemical solutions,flaw distribution,corrosion time andσ_(3) on triaxial stress-strain curves and ultimate failure modes are analyzed and discussed.The results show that the pH value of the chemical solution,corrosion time and the arrangement of preexisting flaws play crucial roles in the cracking behaviors of granite specimens.Type A specimens have the largest peak axial deviatoric stress,followed by Type C,Type D,and Type B specimens,respectively.It is because the decrease in the inclination of preexisting flaws induces the weakening effect due to the decrease in the shadow area along the compaction direction.Under aσ_(3) of 5 MPa,the peak axial deviatoric stress drops by approximately 40.89%,29.08%,4.08%,and 23.53%for pH=2,4,7,and 12,respectively.For intact granite(Type A)specimens,the ultimate failure mode displays a typical shear mode.The connection of two secondary cracks initiated at the tips of preexisting cracks is always the ultimate failure and crack coalescence mode for Type B specimens.The ultimate failure and crack coalescence mode of Types C and D specimens are significantly affected by pH value of the chemical solution,corrosion time andσ_(3),which is different from those of Types A and B specimens due to the differences in flow distributions.展开更多
文摘This issue covers the papers on two special themes:(1)Mineral resources from deep sea—Science and Engineering and(2)Planning and development of underground space and infrastructure for sustainable and liveable cities.
基金Fundamental Research Funds for the Central Universities,Grant/Award Number:2022QN1032。
文摘Strainbursts induced by cyclic disturbance with low frequency(termed as cyclicinduced strainbursts)are major dynamic disasters during deep excavation and mining.There is currently no quantitative criterion available for the prediction of such disastrous events.In this study,based on true triaxial experiments,we analyzed the deformation characteristics,established two novel strain criteria for the cyclic-induced strainbursts,and explained the physical meaning of these criteria.Characteristic strains for the cyclic-induced strainbursts were defined,including the control strain ε_(ctr),the strain caused by the combined dynamic and static loading ε_(sd),and the ultimate strain ε_(u) after strainbursts.As indicated by the results,the deformation evolution of the cyclic-induced strainbursts shows remarkable fatigue characteristics,which resemble that of rock subjected to cyclic loading and unloading.In other words,there are three stages during deformation evolution,namely,initial rapid growth,uniform velocity growth after several periods of disturbance,and sudden sharp growth preceding the burst.The ultimate strain ε_(u) is insensitive to the tangential static stress and disturbance amplitude,but it changes nonlinearly with disturbance frequency.From the perspective of deformation,the occurrence of a cyclic-induced strainburst is controlled by the control strainε_(ctr).Thus,a control strain criterion is proposed;that is,when the stain ε_(sd) is larger than the control strain ε_(ctr),a strainburst will be induced by cyclic disturbance.Moreover,based on the statistical results,a strain ratio criterion is proposed;that is,when the strain ratio ε_(sd)/ε_(u) is greater than 30%,a cyclic-induced strainburst will be induced.
文摘With the increasing scarcity of shallow resources,the mining depth of coal mines has gradually increased,and the safety problem has become increasingly prominent.The grouting technology for deep roadways in fractured rocks is one of key technologies for safe mining of deep resources.This paper by the team of Hongpu Kang,academician of the Chinese Academy of Engineering,systematically summarizes and analyzes the research findings in the theory,design,materials,processes,and equipment for the grouting reinforcement of fractured rocks surrounding the deep roadways.Several field cases in the Kouzidong coal mine are demonstrated on the application of pregrouting in front of heading faces,grouting in excavation,and postgrouting so as to evaluate the effects of these grouting reinforcements.
文摘Deep Underground Science and Engineering(DUSE)publishes this special issue on geothermal energy.The guest editors of this special issue are Prof.Ranjith Pathegama Gamage(Monash University,Australia),Prof.Zhongwei Huang(China University of Petroleum,Beijing,China),and Prof.Bing Bai(Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,China).Geothermal energy is one sustainable and renewable energy and currently a hot research topic in research and development.Geothermal energy supply is one of the long-term efforts for carbon footprint reductions to tackle climate change issues.The development of geothermal energy includes exploration and extraction processes.This special issue is to highlight the challenges on the exploration and extraction of geothermal energy such as initial high cost and difficulties in heat extraction from deep underground.This special issue focuses on new geothermal extraction system,new theory,new technology,new application of latest techniques such as artificial intelligence,and potential environmental effects.
基金the China Postdoctoral Science Foundation(Grant Nos.2016M600396 and 2017T100355)the Fundamental Research Funds for the Central Universities of China(Grant No.B200204001)Jiangsu Natural Resources Science and Technology Fund(Grant No.KJXM2019025)are also acknowledged.
文摘This paper studies the microstructure variation induced by super-absorbent polymer(SAP)to understand the mechanism of macroscopic strength improvement of stabilized soil.The fabric changes of cement elime stabilized soil were analyzed with respect to the variation of SAP content,water content,lime content and curing time,using mercury intrusion porosimetry(MIP)tests.It can be observed that the delimitation pore diameter between inter-and intra-aggregate pores was 0.2 mm for the studied soil,determined through the intrusion/extrusion cycles.Experimental results showed that fabric in both inter-and intra-aggregate pores varied significantly with SAP content,lime content,water content and curing time.Two main changes in fabric due to SAP are identified as:(1)an increase in intra-aggregate pores(<0.2 mm)due to the closer soilecementelime cluster space at higher SAP content;and(2)a decrease in inter-aggregate pores represented by a reduction in small-pores(0.2e2 mm)due to the lower pore volume of soil mixture after water absorption by SAP,and a slight increase in large-pores(>2 mm)due to the shrinkage of SAP particle during the freezeedry process of MIP test.Accordingly,the strength gain due to SAP for cementelime stabilized soil was mainly due to a denser fabric with less interaggregate pores.The cementitious products gradually developed over time,leading to an increase in intra-aggregate pores with an increasing proportion of micro-pores(0.006e0.2 mm).Meanwhile,the inter-aggregate pores were filled by cementitious products,resulting in a decrease in total void ratio.Hence,the strength development over time is attributable to the enhancement of cementation bonding and the refinement of fabric due to the increasing cementitious compounds.
基金The National Natural Science Foundation of China,Grant/Award Number:41702326the Innovative Experts,Long-term Program of Jiangxi Province,Grant/Award Number:jxsq2018106049+1 种基金the Natural Science Foundation of Jiangxi Province,Grant/Award Number:20202ACB214006the Supported by Program of Qingjiang Excellent Young Talents,Jiangxi University of Science and Technology。
文摘In deep-earth engineering,the high earth temperature can significantly affect the rock's mechanical properties,especially when the rock is cooled during the construction process.Accordingly,whether the cooling speed affects the mechanical and physical properties of rocks is worth to be investigated.The present study explored the influence of the cooling rate on the physical and chemical properties of granite heated at 25–800°C.The mechanical and physical properties involved in this study included uniaxial compression strength,peak strain,modulus,P-wave velocity,mass and volume,the change of which could reflect the sensitivity of granite to the cooling rate.Acoustic emission(AE)monitoring,microscopic observation,and X-ray diffraction(XRD)are used to analyze the underlying damage mechanism.It is found that more AE signals and large-scale cracks are accounted for based on the b-value method when the specimens are cooled by water.Furthermore,the microscopic observation by polarized light microscopy indicates that the density,opening degree,and connectivity of the cracks under water cooling mode are higher than that under natural cooling mode.In addition,the XRD illustrates that there is no obvious change in mineral content and diffraction angle at different temperatures,which confirms that the change of mechanical properties is not related to the chemical properties.The present conclusion can provide a perspective to assess the damage caused by different cooling methods to hot rocks.
文摘Myeloperoxidase antineutrophil cytoplasmic antibody(MPO-ANCA)associated vasculitis is an autoimmune disease usually with severe multiple dysfunction syndrome,especially prominent acute renal failure.A 65-year-old woman was admitted with progressive dyspnoea for six months and fever,sputum with blood,pain of the lower extremities and intermittent claudication for two days,indicating multiple organ involvement(respiratory system,blood vessels).The renal involvement was relatively mild,presenting with microscopic haematuria.The chest computed tomography demonstrated multiple pulmonary embolisms.Ultrasound and computed tomography angiography for the lower extremity vessels showed venous and arterial thrombosis.Exclusion of other diseases that can cause multiple organ damage and thrombosis,the positive perinuclear ANCA and MPO-ANCA strongly support the diagnosis of MPO-ANAC-associated vasculitis.The patient’s physical condition has been greatly improved by treatment with corticosteroids and anticoagulation.
文摘Renal amyloidosis secondary to anti-neutrophil cytoplasmic antibody(ANCA)-associated vasculitis is extremely rare.Here,we reported a 77-year-old woman with ANCA-associated vasculitis.Renal biopsy with Masson trichrome staining showed pauci-immune crescentic glomerulonephritis,and electron microscopy showed amyloid deposition in the mesangial area.Immunofluorescence revealed kappa light chain and lambda light chain negative.Bone marrow biopsy revealed no clonal plasma cell.Finally,she was diagnosed as ANCA-associated vasculitis with secondary renal amyloid A amyloidosis.
基金We acknowledge the funding support from the National Natural Science Foundation of China(Grant Nos.52009016 and 52179118)the Fundamental Research Funds for the Central Universities(Grant No.2022QN1032).
文摘The effect of intermediate stress(in situ tunnel axial)on a strainburst is studied with a threedimensional(3D)bonded block distinct element method(DEM).A series of simulations of strainbursts under true triaxial in situ stress conditions(i.e.high tangential stress,moderate intermediate stress and low radial stress)of near-boundary rock masses are performed.Compared with the experimental results,the DEM model is able to capture the stress-strain response,failure pattern and energy balance of strainbursts.The fracturing processes of strainbursts are also numerically reproduced.Numerical results show that,as the intermediate stress increases:(1)The peak strain of strainbursts increases,the yield stress increases,the rock strength increases linearly,and the ratio of yield stress to rock strength decreases,indicating that the precursory information on strainbursts is enhanced;(2)Tensile and shear cracks increase significantly,and slabbing and bending of rock plates are more pronounced;and(3)The stored elastic strain energy and dissipated energy increase linearly,whereas the kinetic energy of the ejected rock fragments increases approximately exponentially,implying an increase in strainburst intensity.By comparing the experimental and numerical results,the effect of intermediate stress on the rock strength of strainbursts is discussed in order to address three key issues.Then,the Mogi criterion is applied to construct new strength criteria for strainbursts by converting the one-face free true triaxial stress state of a strainburst to its equivalent true triaxial stress state.In summary,the effect of intermediate stress on strainbursts is a double-edged sword that can enhance the rock strength and the precursory information of a strainburst,but also increase its intensity.
基金supported by Yunlong Lake Laboratory of Deep Underground Science and Engineering Project(Grant No.104023004)the National Natural Science Foundation of China(Grant Nos.52178328,and 42377190).
文摘This paper presents a regional 3D geological modeling method based on the stacking ensemble technique to overcome the challenges of sparse borehole data in large-scale linear underground projects.The proposed method transforms the 3D geological modeling problem into a stratigraphic property classification problem within a subsurface space grid cell framework.Borehole data is pre-processed and trained using stacking method with five different machine learning algorithms.The resulting modelled regional cells are then classified,forming a regional 3D grid geological model.A case study for an area of 324 km2 along Xuzhou metro lines is presented to demonstrate the effectiveness of the proposed model.The study shows an overall prediction accuracy of 85.4%.However,the accuracy for key stratigraphy layers influencing the construction risk,such as karst carve strata,is only 4.3%due to the limited borehole data.To address this issue,an oversampling technique based on the synthetic minority oversampling technique(SMOTE)algorithm is proposed.This technique effectively increases the number of sparse stratigraphic samples and significantly improves the prediction accuracy for karst caves to 65.4%.Additionally,this study analyzes the impact of sampling distance on model accuracy.It is found that a lower sampling interval results in higher prediction accuracy,but also increases computational resources and time costs.Therefore,in this study,an optimal sampling distance of 1 m is chosen to balance prediction accuracy and computation cost.Furthermore,the number of geological strata is found to have a negative effect on prediction accuracy.To mitigate this,it is recommended to merge less significant stratigraphy layers,reducing computation time.For key strata layers,such as karst caves,which have a significant impact on construction risk,further onsite sampling or oversampling using the SMOTE technique is recommended.
文摘The editors wish to highlight the articles appearing in this issue.The first article,entitled“New physics of supersonic ruptures”by Boris G.Tarasov,concerns the development of a new theory on the potential occurrence of ruptures after deep underground earthquakes.Two other articles belong to our first special theme of“Disaster evolution in deep underground.”The final two articles introduce a nonlocal damage fracture phasefield model for rock‐like materials and the gas–liquid displacement in microcleats for mass transfer through gas‐or water‐driven displacement.These five papers indeed explore various aspects of deep underground science and engineering and constitute an integral component of deep underground fundamentals.
文摘We highlight two articles in this issue:A research article titled“Excavation compensation theory and supplementary technology system for large deformation disasters”by Manchao He et al.and a review article titled“Mineralogy,microstructures and geomechanics of rock salt for underground gas storage”by Veerle Vandeginste et al.
基金funded by the National Natural Science Foundation of China(Nos.82270033 and 81873407)the Natural Science Foundation of Hunan province(No.2022JJ30924)
文摘To the Editor:Allergic bronchopulmonary aspergillosis(ABPA)is an allergic lung disease caused by hypersensitivity to antigens from Aspergillus,and it most commonly occurs in patients with asthma or cysticbrosis.[1]The main clinical characteristics of the disease are those related to elevated serum immunoglubulin(Ig)E level,positive Aspergillus fumigatus(A.fumigatus)specic IgE/IgG,repeated pulmonary inltration,and bronchiectasis.However,due to the lack of unied diagnostic criteria and screening methods,ABPA is always underdiagnosed.In 2021,new diagnostic criteria were proposed for allergic bronchopulmonary mycosis(ABPM)in the Japanese population.
基金supported by China Postdoctoral Science Foundation(No.2020M680007)Beijing Postdoctoral Research Foundation(No.2020-zz-087)+1 种基金National Natural Science Foundation of China(Nos.51478027 and 51174012)Fundamental Research Funds for Beijing Civil Engineering and Architecture(No.X20031)。
文摘This study aims at proposing a reasonable roughness parameter that can reflect the peak shear strength(PSS)of rock joints.Firstly,the contribution of the asperities with different apparent dip angles to shear strength is studied.Then the shear strength of the entire joint asperities is derived.The results showed that the PSS of the entire joint asperities is proportional to a key parameter hs,which is related to the geometric character of the joint surface and the joint material properties.The parameter hsis taken as the new roughness parameter,and it is reasonable to associate the PSS with the geometric characteristics of the joint surface.Based on the new roughness parameter and shear test results of 20 sets of joint specimens,a new PSS model for rock joints is proposed.The new model is validated with the artificial joints in this paper and real rock joints in published studies.Results showed that it is suitable for different types of rock joints except for gneiss joints.The new model has the form of the Mohr-Coulomb model,which can directly reflect the relationship between the 3 D roughness parameters and the peak dilation angle.
基金support of the National Natural Science Foundation of China (Grant Nos. 52174133 and 51809263)China Atomic Energy Authority。
文摘The sealing performance of a bentonite barrier is highly dependent on its seepage characteristics, which are directly related to the characteristics of its pore structure. Based on scanning electron microscopy(SEM) and focused ion beam-SEM(FIB-SEM), the pore structure of bentonite was characterized at different scales. First, a reasonable gray threshold was determined through back analysis, and the image was binarized based on the threshold. In addition, binary images were used to analyze bentonite’s pore structure(porosity and pore size distribution). Furthermore, the effects of different algorithms on the pore structure characterization were evaluated. Then, permeability calculations were performed based on the previous pore structure characteristics and a modified permeability prediction model. For permeability prediction based on the three-dimensional model, the effect of pore tortuosity was also considered. Finally, the accuracy of numerical calculations was verified by conducting macroscopic gas and alcohol permeability experiments. This approach provides a better understanding of the microscale mechanism of gas transport in bentonite and the importance of pore structures at different scales in determining its seepage characteristics.
文摘Deep underground provides enormous resources for mankind,such as energy,minerals,and water.It can also provide effective solutions for pollutant disposal,such as nuclear waste disposal and CO_(2) geosequestration,as well as storage spaces.In addition,deep underground is of great necessity because it provides an ultra-quiet environment for scientific research facilities for advanced experiments in physics,chemistry,and medicine.
基金Fundamental Research Funds for the Central Universities,Grant/Award Number:2022QN1032。
文摘This paper introduces the establishment of deep underground infrastructure for science and engineering research.First,the representative deep underground research laboratories and facilities in the world and their functions were summarized and reviewed.Then,the plan and service target of China Yulong Lake Laboratory were proposed for the storage of resources and energy,as well as the sealing of hazardous waste in deep underground space.On this basis,this paper reveals how the facility addresses its key scientific issue on“The law of fluid matter migration in deep underground space”and engineering significance.Finally,the construction progress of the facility components was demonstrated in details.As is hoped,this paper would provide useful reference to the deep underground research community;meanwhile,international collaboration on deep underground research is highly welcome.
基金supported by the National Natural Science Foundation of China (Grant Nos.12172036 and 51774018)the Program for Changjiang Scholars and Innovative Research Team in University (IRT_17R06)National Basic Research Program of China (Grant No.2015CB0578005).
文摘In this paper,how to determine the Weibull modulus of a fracture strength distribution is discussed with its physical implications for quasi-brittle materials.Based on the Markov chain assumption,it is shown that the lifetime(i.e.,the time taken for formation of a critical defect)in a quasi-brittle material can be described by a gamma probabilistic distribution function.Prior to macroscopic failure,the effective number of energy barriers to be overcome is determined by the slope of the energy barrier spectrum,which is equivalent to the Weibull modulus.Based on a fracture mechanics model,the fracture energy barrier spectral slope and Weibull modulus can be calculated theoretically.Furthermore,such a model can be extended to take into account the crack interactions and defect-induced degradation.The predicted Weibull modulus is good agreement with that derived from available experimental results.
基金the National Natural Science Foundation of China(Grant No.51708016)the Scientific Research Program of Beijing Municipal Education Commission(KM202110016014)the Pyramid Talent Training Project of Beijing University of Civil Engineering and Architecture(Grant No.JDYC20200307).
文摘The tensile creep fracture behaviors in brittle solids are of great significance for the safety evaluation of brittle solid engineering.However,micromechanics-based tensile creep fracture behavior is rarely studied.In this study,a micromechanics-based method for predicting direct tensile creep fractures is presented.This method is established by combining the suggested expression of the mode-I stress intensity factor,the subcritical crack growth law,and the relationship between wing crack length and axial strain.This suggested mode-I stress intensity factor is formulated by the use of the basic theory of fracture mechanics under different loading modes.The rationality of the proposed tensile creep fracture model is verified by comparing with the experimental results.The correspondences of time-dependent axial strain,strain rate,wing crack length,and crack velocity are plotted under constant stress and stepping stress during tensile creep fracture.The effects of the initial crack size,inclination angle and density on the crack initiation stress,tensile strength,tensile creep fracture time,steady-state strain rate,initial strain,crack coalescence strain,and failure strain are discussed.
基金This study has been partially funded by the National Key Research and Development Program of China,China(Grant No.2020YFA0711800)the National Natural Science Foundation of China(Grant Nos.51734009,51979272,and 52179118)Natural Science Foundation of Jiangsu Province,China(No.BK20211584).These supports are gratefully acknowledged.
文摘Four types of granite specimens were prepared and treated by chemical corrosion for 5 and 30 days,which were then used to carry out triaxial compression tests under different confining pressuresσ_(3).Type A is the intact sample with no preexisting flaws.Types B and C are the samples containing two relatively low-dip flaws and two relatively high-dip flaws,respectively.Type D is the sample including both relatively low-dip and relatively high-dip flaws.The influences of pH value of chemical solutions,flaw distribution,corrosion time andσ_(3) on triaxial stress-strain curves and ultimate failure modes are analyzed and discussed.The results show that the pH value of the chemical solution,corrosion time and the arrangement of preexisting flaws play crucial roles in the cracking behaviors of granite specimens.Type A specimens have the largest peak axial deviatoric stress,followed by Type C,Type D,and Type B specimens,respectively.It is because the decrease in the inclination of preexisting flaws induces the weakening effect due to the decrease in the shadow area along the compaction direction.Under aσ_(3) of 5 MPa,the peak axial deviatoric stress drops by approximately 40.89%,29.08%,4.08%,and 23.53%for pH=2,4,7,and 12,respectively.For intact granite(Type A)specimens,the ultimate failure mode displays a typical shear mode.The connection of two secondary cracks initiated at the tips of preexisting cracks is always the ultimate failure and crack coalescence mode for Type B specimens.The ultimate failure and crack coalescence mode of Types C and D specimens are significantly affected by pH value of the chemical solution,corrosion time andσ_(3),which is different from those of Types A and B specimens due to the differences in flow distributions.