0 INTRODUCTION During the geological evolution process,tectonic activities coupled with anthropogenic engineering disturbances have collectively contributed to the development of complex fracture-filling networks with...0 INTRODUCTION During the geological evolution process,tectonic activities coupled with anthropogenic engineering disturbances have collectively contributed to the development of complex fracture-filling networks within rock masses(Feng et al.,2024;Tan et al.,2020;Li et al.,2019).The particle size distribution of infilling materials within fractures is susceptible to multiple controlling factors,including material composition,seepage-induced erosion,and tectonic disturbances(Zhang et al.,2024;Tan et al.,2023).展开更多
Weak interlayers play a crucial role in the seismic performance of bedding slopes;however,the effects of structural surface development within these layers remain underexplored.This study presents two scaled models of...Weak interlayers play a crucial role in the seismic performance of bedding slopes;however,the effects of structural surface development within these layers remain underexplored.This study presents two scaled models of bedding slopes,each with different weak interlayers:one with a homogeneous weak layer and another with discontinuous interfaces.Shaking table tests were conducted to compare their seismic performance.The results show that the peak ground acceleration(PGA)values above the weak interlayer in model A were significantly higher than those in model B,with the differences increasing as the input wave amplitude increased.The peak earth pressure(PEP)values at the tensile failure boundary at the rear edge of model A were also higher,whereas those within the weak layer at the toe of model A were lower than those in model B.Deformation analysis revealed that the maximum principal strain in model A initially appeared at the upper part of the tensile failure boundary,while the maximum shear strain was concentrated near the rear edge within the weak layer.In contrast,model B exhibited the opposite strain distribution.These findings provide insight into the impact of weak interlayers on the dynamic response and deformation of bedding slopes,highlighting the importance of considering this factor in seismic landslide investigations and failure mode predictions.展开更多
By applying experimental method, the bolt stress and supporting mechanism is studied during the deformation process of a rock mass containing a weak interlayer. The force measuring bolt is installed manually and instr...By applying experimental method, the bolt stress and supporting mechanism is studied during the deformation process of a rock mass containing a weak interlayer. The force measuring bolt is installed manually and instrumented five pairs of symmetrical strain gauges. The experimental results show that the fully grouted bolt suffers tensile, compressive, bending and shear stress at the same time. The bolt stress evolution is closely related to the deformation stages of the rock mass which are very gradually varying stage, gradually varying stage at the pre-peak and suddenly varying stage at the post peak stage.The axial compressive stress in the bolt is mainly induced by the moment. Thus, in most cases the axial compressive stress is distributed on one side of the bolt. For axial stresses, induced by the axial force and the bending moment at the post-peak stage, three types of changing are observed, viz. increasingincreasing type, decreasing-increasing type and increasing-decreasing type. The stress characteristics of the bolt section in the weak interlayer are significantly different from those in the hard rock. The failure models of the anchored bolt are tensile failure and shear failure, respectively. The bolt not only provides constraints on the free surface of the rock mass, but also resists the axial and lateral loading by the bending moment. This study provides valuable guidelines for bolting support design and its safety assessment.展开更多
The load transfer characteristics of a tensile anchor in the rock mass with weak interlayers were investigated,considering the nonuniform stress of the horizontally layered rock mass along anchors.An improved shear-sl...The load transfer characteristics of a tensile anchor in the rock mass with weak interlayers were investigated,considering the nonuniform stress of the horizontally layered rock mass along anchors.An improved shear-slipping model was proposed to describe the stress evolution characteristics of the bolt-rock interface.Based on the improved model,analytical solutions of the axial force,shear stress distribution and load-displacement relationship considering the residual stress stage were established.The effects of the stratigraphic sequence,pulling force and bolt diameter on the stress distribution of the anchorage interface were evaluated by using analytical solutions.The results were verified by applying the finite difference numerical simulation method.The sensitivity of each parameter to the axial force and shear stress of the rock bolt was determined based on calculation of the sensitivity coefficient.The study results show that the axial force and shear stress tend to decrease nonuniformly along the rock bolt towards the anchorage depth.Due to the existence of weak interlayers,the shear stress mutates at the weak and hard rock interface,and the axial force appears to“rebound”at the bottom of the anchored section.Lithology has more significant effects on the axial force and shear stress at the bottom of the anchor than at the top of the anchor.The pulling force is more sensitive to the anchor stress than stratigraphic sequence when the bolt diameter is determined.This study provides a theoretical framework for the fundamental problem of tensile bolts in horizontally or vertically laminated rock masses,providing a theoretical basis for anchor design.展开更多
The shear behavior of large-scale weak intercalation shear zones(WISZs)often governs the stability of foundations,rock slopes,and underground structures.However,due to their wide distribution,undulating morphology,com...The shear behavior of large-scale weak intercalation shear zones(WISZs)often governs the stability of foundations,rock slopes,and underground structures.However,due to their wide distribution,undulating morphology,complex fabrics,and varying degrees of contact states,characterizing the shear behavior of natural and complex large-scale WISZs precisely is challenging.This study proposes an analytical method to address this issue,based on geological fieldwork and relevant experimental results.The analytical method utilizes the random field theory and Kriging interpolation technique to simplify the spatial uncertainties of the structural and fabric features for WISZs into the spatial correlation and variability of their mechanical parameters.The Kriging conditional random field of the friction angle of WISZs is embedded in the discrete element software 3DEC,enabling activation analysis of WISZ C2 in the underground caverns of the Baihetan hydropower station.The results indicate that the activation scope of WISZ C2 induced by the excavation of underground caverns is approximately 0.5e1 times the main powerhouse span,showing local activation.Furthermore,the overall safety factor of WISZ C2 follows a normal distribution with an average value of 3.697.展开更多
Due to the weak interlayer interactions,the binary Ⅲ-Ⅵ chalcogenides Ga Se can exist in several distinct polymorphs.Among them,the so-called β-and ε-phases simultaneously exhibit favorable total energies and moder...Due to the weak interlayer interactions,the binary Ⅲ-Ⅵ chalcogenides Ga Se can exist in several distinct polymorphs.Among them,the so-called β-and ε-phases simultaneously exhibit favorable total energies and moderate band gaps,which offer a good platform to explore their thermoelectric properties.Here,we demonstrate by first-principles calculations that the two systems have very similar band structures and phonon dispersions,despite different stacking sequences between adjacent layers.Interestingly,the lattice thermal conductivity of ε-GaSe is obviously lower than that of β-GaSe,which is inherently tied to stronger lattice anharmonicity caused by bonding heterogeneity.Besides,both systems exhibit higher p-type power factors due to doubly degenerate bands with weaker dispersions around the valence band maximum.As a consequence,a significantly enhanced p-type figure-of-merit of 2.1 can be realized at 700 K along the out-of-plane direction of theε-phase.展开更多
The weak interlayer van der Waals(vdW) interactions in two-dimensional(2D) vdW materials enable sliding ferroelectricity as an effective strategy for modulating their intrinsic properties. In this work, we systematica...The weak interlayer van der Waals(vdW) interactions in two-dimensional(2D) vdW materials enable sliding ferroelectricity as an effective strategy for modulating their intrinsic properties. In this work, we systematically investigate the influence of interlayer sliding on the electronic behavior of PtSe_(2) using density functional theory(DFT) calculations. Our results demonstrate that interlayer sliding induces a pronounced photocurrent spanning the short-wavelength infrared to visible spectral ranges. Remarkably, under an applied gate voltage, the sliding ferroelectric PtSe_(2) exhibits anomalously enhanced photovoltaic performance and an ultrahigh extinction ratio.Transmission spectral analysis reveals that this phenomenon originates from band structure modifications driven by energy-level transitions. Furthermore, the observed photocurrent enhancement via sliding ferroelectricity demonstrates universality across diverse platinum-based optoelectronic devices. This study introduces a novel paradigm for tailoring the intrinsic characteristics of 2D vdW semiconductors, expanding the design space for next-generation ferroelectric materials in advanced optoelectronic applications.展开更多
Rock masses are often exposed to dynamic loads such as earthquakes and mechanical disturbances in practical engineering scenarios.The existence of underground caverns and weak geological structures like columnar joint...Rock masses are often exposed to dynamic loads such as earthquakes and mechanical disturbances in practical engineering scenarios.The existence of underground caverns and weak geological structures like columnar jointed rock masses(CJRMs)and interlayer shear weakness zones(ISWZs)with inferior mechanical properties,significantly undermines the overall structural stability.To tackle the dynamic loading issues in the process of constructing subterranean caverns,a programmable modeling approach was utilized to reconstruct a large-scale underground cavern model incorporating ISWZs and columnar joints(CJs).By conducting dynamic simulations with varying load orientations,the analyses focused on the failure patterns,deformation characteristics,and acoustic emission activity within the caverns.Results revealed that the failure modes of the underground caverns under dynamic loading were predominantly tensile failures.Under X-direction loading,the failed elements were mainly distributed parallel to the CJs,while under Y-direction loading,they were distributed parallel to the transverse weak structural planes.Furthermore,the dynamic stability of the overall structure varied with the number of caverns.The dual-cavern model demonstrated the highest stability under X-direction loading,while the single-cavern model was the least stable.Under Y-direction loading,the cavern stability increased with the number of caverns.Importantly,different weak structures affected the dynamic response of caverns in different ways;the CJRMs were the primary contributors to structural failure,while ISWZs could mitigate the rock mass failure induced by CJs.The findings could offer valuable insights for the dynamic stability analysis of caverns containing CJRMs and ISWZs.展开更多
Three-dimensional(3D)printing technology is increasingly used in experimental research of geotechnical engineering.Compared to other materials,3D layer-by-layer printing specimens are extremely similar to the inherent...Three-dimensional(3D)printing technology is increasingly used in experimental research of geotechnical engineering.Compared to other materials,3D layer-by-layer printing specimens are extremely similar to the inherent properties of natural layered rock masses.In this paper,soft-hard interbedded rock masses with different dip angles were prepared based on 3D printing(3DP)sand core technology.Uniaxial compression creep tests were conducted to investigate its anisotropic creep behavior based on digital imaging correlation(DIC)technology.The results show that the anisotropic creep behavior of the 3DP soft-hard interbedded rock mass is mainly affected by the dip angles of the weak interlayer when the stress is at low levels.As the stress level increases,the effect of creep stress on its creep anisotropy increases significantly,and the dip angle is no longer the main factor.The minimum value of the long-term strength and creep failure strength always appears in the weak interlayer within 30°–60°,which explains why the failure of the layered rock mass is controlled by the weak interlayer and generally emerges at 45°.The tests results are verified by comparing with theoretical and other published studies.The feasibility of the 3DP soft-hard interbedded rock mass provides broad prospects and application values for 3DP technology in future experimental research.展开更多
As a kind of special material in geotechnical engineering, the mudded weak interlayer plays a crucial part in slope stability. In this paper, we presented a method to determine the threshold value of section micrograp...As a kind of special material in geotechnical engineering, the mudded weak interlayer plays a crucial part in slope stability. In this paper, we presented a method to determine the threshold value of section micrographs of the mudded weak interlayer in slope during its meso-structure qualification process. Some soil tests, scanning electron microscopy（SEM） and image segmentation technology were performed to fulfill our purpose. Specifically, the relation between 3 D-porosity and the threshold was obtained by least square fitting of the threshold-porosity curves and a simplified pore equivalent model. Using this relation and the 3 D-porosity determined by soil experiments, we can figure out the polynomial equation of the threshold value. The threshold values obtained by the other existing methods in literature were employed to validate our present results.展开更多
基金supported by the National Natural Science Foundation of China(No.42090054)。
文摘0 INTRODUCTION During the geological evolution process,tectonic activities coupled with anthropogenic engineering disturbances have collectively contributed to the development of complex fracture-filling networks within rock masses(Feng et al.,2024;Tan et al.,2020;Li et al.,2019).The particle size distribution of infilling materials within fractures is susceptible to multiple controlling factors,including material composition,seepage-induced erosion,and tectonic disturbances(Zhang et al.,2024;Tan et al.,2023).
基金funding support from the National Nature Science Foundation of China(Grant No.41931296)the Open Research Project of Sichuan Provincial Key Laboratory for Major Hazard Source Monitoring and Control(Grant No.KFKT2023-4)the 57#Project(Grant No.JH2024015).
文摘Weak interlayers play a crucial role in the seismic performance of bedding slopes;however,the effects of structural surface development within these layers remain underexplored.This study presents two scaled models of bedding slopes,each with different weak interlayers:one with a homogeneous weak layer and another with discontinuous interfaces.Shaking table tests were conducted to compare their seismic performance.The results show that the peak ground acceleration(PGA)values above the weak interlayer in model A were significantly higher than those in model B,with the differences increasing as the input wave amplitude increased.The peak earth pressure(PEP)values at the tensile failure boundary at the rear edge of model A were also higher,whereas those within the weak layer at the toe of model A were lower than those in model B.Deformation analysis revealed that the maximum principal strain in model A initially appeared at the upper part of the tensile failure boundary,while the maximum shear strain was concentrated near the rear edge within the weak layer.In contrast,model B exhibited the opposite strain distribution.These findings provide insight into the impact of weak interlayers on the dynamic response and deformation of bedding slopes,highlighting the importance of considering this factor in seismic landslide investigations and failure mode predictions.
基金support of the National Basic Research 973 Program of China (No.2013CB036003)the National Natural Science Foundation of China (No.51374198)the National Natural Science Foundation young investigator grant program of China (Nos.51204163,51504247,and 51404255)
文摘By applying experimental method, the bolt stress and supporting mechanism is studied during the deformation process of a rock mass containing a weak interlayer. The force measuring bolt is installed manually and instrumented five pairs of symmetrical strain gauges. The experimental results show that the fully grouted bolt suffers tensile, compressive, bending and shear stress at the same time. The bolt stress evolution is closely related to the deformation stages of the rock mass which are very gradually varying stage, gradually varying stage at the pre-peak and suddenly varying stage at the post peak stage.The axial compressive stress in the bolt is mainly induced by the moment. Thus, in most cases the axial compressive stress is distributed on one side of the bolt. For axial stresses, induced by the axial force and the bending moment at the post-peak stage, three types of changing are observed, viz. increasingincreasing type, decreasing-increasing type and increasing-decreasing type. The stress characteristics of the bolt section in the weak interlayer are significantly different from those in the hard rock. The failure models of the anchored bolt are tensile failure and shear failure, respectively. The bolt not only provides constraints on the free surface of the rock mass, but also resists the axial and lateral loading by the bending moment. This study provides valuable guidelines for bolting support design and its safety assessment.
基金supported by the National Key R&D Program of China(Nos.2018YFC1505300,2017YFC1501304)National Natural Science Foundation of China(Grout Nos.42090054,41922055 and 41931295)+2 种基金the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)(No.CUGGC09)Research Project of China Three Gorges Corporation(No.2019073)the Zhejiang Huadong Construction Engineering Co.,Ltd.(No.KY2019-HDJS-07)。
文摘The load transfer characteristics of a tensile anchor in the rock mass with weak interlayers were investigated,considering the nonuniform stress of the horizontally layered rock mass along anchors.An improved shear-slipping model was proposed to describe the stress evolution characteristics of the bolt-rock interface.Based on the improved model,analytical solutions of the axial force,shear stress distribution and load-displacement relationship considering the residual stress stage were established.The effects of the stratigraphic sequence,pulling force and bolt diameter on the stress distribution of the anchorage interface were evaluated by using analytical solutions.The results were verified by applying the finite difference numerical simulation method.The sensitivity of each parameter to the axial force and shear stress of the rock bolt was determined based on calculation of the sensitivity coefficient.The study results show that the axial force and shear stress tend to decrease nonuniformly along the rock bolt towards the anchorage depth.Due to the existence of weak interlayers,the shear stress mutates at the weak and hard rock interface,and the axial force appears to“rebound”at the bottom of the anchored section.Lithology has more significant effects on the axial force and shear stress at the bottom of the anchor than at the top of the anchor.The pulling force is more sensitive to the anchor stress than stratigraphic sequence when the bolt diameter is determined.This study provides a theoretical framework for the fundamental problem of tensile bolts in horizontally or vertically laminated rock masses,providing a theoretical basis for anchor design.
基金support from the Key Projects of the Yalong River Joint Fund of the National Natural Science Foundation of China(Grant No.U1865203)the Innovation Team of Changjiang River Scientific Research Institute(Grant Nos.CKSF2021715/YT and CKSF2023305/YT)。
文摘The shear behavior of large-scale weak intercalation shear zones(WISZs)often governs the stability of foundations,rock slopes,and underground structures.However,due to their wide distribution,undulating morphology,complex fabrics,and varying degrees of contact states,characterizing the shear behavior of natural and complex large-scale WISZs precisely is challenging.This study proposes an analytical method to address this issue,based on geological fieldwork and relevant experimental results.The analytical method utilizes the random field theory and Kriging interpolation technique to simplify the spatial uncertainties of the structural and fabric features for WISZs into the spatial correlation and variability of their mechanical parameters.The Kriging conditional random field of the friction angle of WISZs is embedded in the discrete element software 3DEC,enabling activation analysis of WISZ C2 in the underground caverns of the Baihetan hydropower station.The results indicate that the activation scope of WISZ C2 induced by the excavation of underground caverns is approximately 0.5e1 times the main powerhouse span,showing local activation.Furthermore,the overall safety factor of WISZ C2 follows a normal distribution with an average value of 3.697.
基金supported by the National Natural Science Foundation of China(Grant Nos.62074114 and 12474019)。
文摘Due to the weak interlayer interactions,the binary Ⅲ-Ⅵ chalcogenides Ga Se can exist in several distinct polymorphs.Among them,the so-called β-and ε-phases simultaneously exhibit favorable total energies and moderate band gaps,which offer a good platform to explore their thermoelectric properties.Here,we demonstrate by first-principles calculations that the two systems have very similar band structures and phonon dispersions,despite different stacking sequences between adjacent layers.Interestingly,the lattice thermal conductivity of ε-GaSe is obviously lower than that of β-GaSe,which is inherently tied to stronger lattice anharmonicity caused by bonding heterogeneity.Besides,both systems exhibit higher p-type power factors due to doubly degenerate bands with weaker dispersions around the valence band maximum.As a consequence,a significantly enhanced p-type figure-of-merit of 2.1 can be realized at 700 K along the out-of-plane direction of theε-phase.
基金supported by the National Key Research and Development Program of China (Grant No. 2024YFB3211701)the National Natural Science Foundation of China (Grant Nos. T2222011, 62174026, and 12274234)+1 种基金the National Key Research and Development Program of China (Grant Nos. 2023YFB3611400 and 2019YFA0308000)the Fundamental Research Funds for the Central Universities (Grant No. 242023k30027)。
文摘The weak interlayer van der Waals(vdW) interactions in two-dimensional(2D) vdW materials enable sliding ferroelectricity as an effective strategy for modulating their intrinsic properties. In this work, we systematically investigate the influence of interlayer sliding on the electronic behavior of PtSe_(2) using density functional theory(DFT) calculations. Our results demonstrate that interlayer sliding induces a pronounced photocurrent spanning the short-wavelength infrared to visible spectral ranges. Remarkably, under an applied gate voltage, the sliding ferroelectric PtSe_(2) exhibits anomalously enhanced photovoltaic performance and an ultrahigh extinction ratio.Transmission spectral analysis reveals that this phenomenon originates from band structure modifications driven by energy-level transitions. Furthermore, the observed photocurrent enhancement via sliding ferroelectricity demonstrates universality across diverse platinum-based optoelectronic devices. This study introduces a novel paradigm for tailoring the intrinsic characteristics of 2D vdW semiconductors, expanding the design space for next-generation ferroelectric materials in advanced optoelectronic applications.
基金funded by the National Natural Science Foundation of China(Grant Nos.42077251,41807269,and U1865203).
文摘Rock masses are often exposed to dynamic loads such as earthquakes and mechanical disturbances in practical engineering scenarios.The existence of underground caverns and weak geological structures like columnar jointed rock masses(CJRMs)and interlayer shear weakness zones(ISWZs)with inferior mechanical properties,significantly undermines the overall structural stability.To tackle the dynamic loading issues in the process of constructing subterranean caverns,a programmable modeling approach was utilized to reconstruct a large-scale underground cavern model incorporating ISWZs and columnar joints(CJs).By conducting dynamic simulations with varying load orientations,the analyses focused on the failure patterns,deformation characteristics,and acoustic emission activity within the caverns.Results revealed that the failure modes of the underground caverns under dynamic loading were predominantly tensile failures.Under X-direction loading,the failed elements were mainly distributed parallel to the CJs,while under Y-direction loading,they were distributed parallel to the transverse weak structural planes.Furthermore,the dynamic stability of the overall structure varied with the number of caverns.The dual-cavern model demonstrated the highest stability under X-direction loading,while the single-cavern model was the least stable.Under Y-direction loading,the cavern stability increased with the number of caverns.Importantly,different weak structures affected the dynamic response of caverns in different ways;the CJRMs were the primary contributors to structural failure,while ISWZs could mitigate the rock mass failure induced by CJs.The findings could offer valuable insights for the dynamic stability analysis of caverns containing CJRMs and ISWZs.
基金the support of the National Natural Science Foundation of China(Grant Nos.42207199,52179113,42272333)Zhejiang Postdoctoral Scientific Research Project(Grant Nos.ZJ2022155,ZJ2022156)。
文摘Three-dimensional(3D)printing technology is increasingly used in experimental research of geotechnical engineering.Compared to other materials,3D layer-by-layer printing specimens are extremely similar to the inherent properties of natural layered rock masses.In this paper,soft-hard interbedded rock masses with different dip angles were prepared based on 3D printing(3DP)sand core technology.Uniaxial compression creep tests were conducted to investigate its anisotropic creep behavior based on digital imaging correlation(DIC)technology.The results show that the anisotropic creep behavior of the 3DP soft-hard interbedded rock mass is mainly affected by the dip angles of the weak interlayer when the stress is at low levels.As the stress level increases,the effect of creep stress on its creep anisotropy increases significantly,and the dip angle is no longer the main factor.The minimum value of the long-term strength and creep failure strength always appears in the weak interlayer within 30°–60°,which explains why the failure of the layered rock mass is controlled by the weak interlayer and generally emerges at 45°.The tests results are verified by comparing with theoretical and other published studies.The feasibility of the 3DP soft-hard interbedded rock mass provides broad prospects and application values for 3DP technology in future experimental research.
基金Funded by the National Natural Science Foundation of China(No.51574201)the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Foundation(Chengdu University of Technology)(No.SKLGP2015K006)the Scientific&Technical Youth Innovation Group(Southwest Petroleum University)(No.2015CXTD05)
文摘As a kind of special material in geotechnical engineering, the mudded weak interlayer plays a crucial part in slope stability. In this paper, we presented a method to determine the threshold value of section micrographs of the mudded weak interlayer in slope during its meso-structure qualification process. Some soil tests, scanning electron microscopy（SEM） and image segmentation technology were performed to fulfill our purpose. Specifically, the relation between 3 D-porosity and the threshold was obtained by least square fitting of the threshold-porosity curves and a simplified pore equivalent model. Using this relation and the 3 D-porosity determined by soil experiments, we can figure out the polynomial equation of the threshold value. The threshold values obtained by the other existing methods in literature were employed to validate our present results.
