Accurate dynamic modeling of landslides could help understand the movement mechanisms and guide disaster mitigation and prevention.Discontinuous deformation analysis(DDA)is an effective approach for investigating land...Accurate dynamic modeling of landslides could help understand the movement mechanisms and guide disaster mitigation and prevention.Discontinuous deformation analysis(DDA)is an effective approach for investigating landslides.However,DDA fails to accurately capture the degradation in shear strength of rock joints commonly observed in high-speed landslides.In this study,DDA is modified by incorporating simplified joint shear strength degradation.Based on the modified DDA,the kinematics of the Baige landslide that occurred along the Jinsha River in China on 10 October 2018 are reproduced.The violent starting velocity of the landslide is considered explicitly.Three cases with different violent starting velocities are investigated to show their effect on the landslide movement process.Subsequently,the landslide movement process and the final accumulation characteristics are analyzed from multiple perspectives.The results show that the violent starting velocity affects the landslide motion characteristics,which is found to be about 4 m/s in the Baige landslide.The movement process of the Baige landslide involves four stages:initiation,high-speed sliding,impact-climbing,low-speed motion and accumulation.The accumulation states of sliding masses in different zones are different,which essentially corresponds to reality.The research results suggest that the modified DDA is applicable to similar high-level rock landslides.展开更多
In practical engineering,due to the noncontinuity characteristics of joints in rock slopes,in addition to plane failure,stepped sliding failure may occur for intermittently jointed rock slopes.Especially for intermitt...In practical engineering,due to the noncontinuity characteristics of joints in rock slopes,in addition to plane failure,stepped sliding failure may occur for intermittently jointed rock slopes.Especially for intermittently bedding jointed rock slopes,the correlation and difference in strength parameters between joints and rock bridges,along with the various failure modes and intermittency of rock bridges,contribute to the complexity of stepped failure modes and the unpredictability of failure regions.Based on the upper-bound limit analysis method and multi-sliders step-path failure mode,considering the shear and tensile failure of rock bridges and the weakened relationship between the strength parameters of rock bridges and jointed surfaces,by introducing the modified M-C failure criterion and the formula for calculating the energy consumption of tensile failure of rock bridges,two failure mechanisms are constructed to obtain the safety factor(F_(s))of intermittently jointed rock slopes.The sequential quadratic programming method is used to obtain the optimal upper-bound solution for F_(s).The influence of multiple key parameters(slope height H,horizontal distance L,Slope angleβ,shear strength parameters of the rock bridgeφr and cr,Dimensionless parameter u,weakening coefficients of the internal friction angle and cohesion between the rock bridges and joint surfaces Kφand Kc)on the stability analysis of intermittently jointed rock slopes under the shear failure mode of rock bridges as well as under the tensile failure mode is also explored.The reliability of the failure mechanisms is verified by comparative analysis with theoretical results,numerical results,and landslide cases,and the variation rules of F_(s)with each key parameter are obtained.The results show that F_(s) varies linearly withφr and cr of the rock bridge and with K_(φ)and K_(c),whereas F_(s)changes nonlinearly with H and L.In particular,with the increase in Kφand Kc,Fs increases by approximately 52.78%and 171.02%on average,respectively.For rock bridge tensile failure,F_(s) shows a nonlinearly positive correlation withφr,cr,Kφand Kc.In particular,with the increase in Kφand Kc,Fs increases by approximately 13%and 61.69%on average,respectively.Fs decreases rapidly with increasing slope gradientβand decreasing dimensionless parameterμ.When Kφand Kc are both less than 1.0,the stepped sliding surface occurs more easily than the plane failure surface,especially in the case of tensile failure of the rock bridge.In addition,rock slopes with higher strength parameters,taller heights,and greater weakening coefficients are prone to rock bridge tension failure with lower Fs,and more attention should be given to the occurrence of such accidents in actual engineering.展开更多
为研究乳清多肽(whey protein hydrolysates,WPH)对反复冻融猪肉糜氧化和品质的影响规律及机理,本实验将不同质量分数(5%、10%、15%)WPH添加到生猪肉糜中,进行不同冻融循环(0~9)处理,检测冻融后肉糜解冻损失、硫代巴比妥酸(thiobarbitur...为研究乳清多肽(whey protein hydrolysates,WPH)对反复冻融猪肉糜氧化和品质的影响规律及机理,本实验将不同质量分数(5%、10%、15%)WPH添加到生猪肉糜中,进行不同冻融循环(0~9)处理,检测冻融后肉糜解冻损失、硫代巴比妥酸(thiobarbituricacid reactive substances,TBARS)值、挥发性盐基氮(total volatile base nitrogen,TVB-N)值、质构特性、流变学模量损耗、蛋白羰基含量以及拉曼光谱的变化情况。结果表明,未经冻融时,样品组与空白组各指标之间都无明显差异(P>0.05)。冻融处理后,猪肉糜的解冻损失率由2.67%~2.93%升高至7.00%~12.4%,其中15%WPH明显抑制了解冻损失的增加(P<0.05),提高了肉糜保水性。当冻融循环达到7~9次后,添加15%WPH组抑制肉糜TVB-N值、TBARS值以及羰基含量升高均比空白组和未水解乳清多肽组效果好(P<0.05)。在质构方面,随着冻融次数的增加,猪肉糜硬度、弹性、内聚性和咀嚼性均呈现明显的下降趋势。冻融9次时,15%WPH可使猪肉糜咀嚼性从9.63 g升高到17 g;冻融5次时,15%WPH组的弹性高达到0.69,超过丁基羟基茴香醚(butylatedhydroxyanisole,BHA)阳性空白组;WPH组和BHA组的硬度和内聚性均显著高于空白组;不同添加量WPH对猪肉糜质构都有改善作用,其中高剂量组效果最好。流变学结果显示,WPH组猪肉糜损耗模量G’’降低比较明显。拉曼光谱表明,添加15%WPH有效抑制了冻融循环过程中肉蛋白α-螺旋含量下降、β-折叠含量上升的现象,保护了蛋白质二级结构。实验表明,在冻融循环过程中,WPH起到抑制猪肉糜氧化和改善产品品质的作用。展开更多
基金supported by the National Natural Science Foundations of China(grant numbers U22A20601 and 52209142)the Opening fund of State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(Chengdu University of Technology)(grant number SKLGP2022K018)+1 种基金the Science&Technology Department of Sichuan Province(grant number 2023NSFSC0284)the Science and Technology Major Project of Tibetan Autonomous Region of China(grant number XZ202201ZD0003G)。
文摘Accurate dynamic modeling of landslides could help understand the movement mechanisms and guide disaster mitigation and prevention.Discontinuous deformation analysis(DDA)is an effective approach for investigating landslides.However,DDA fails to accurately capture the degradation in shear strength of rock joints commonly observed in high-speed landslides.In this study,DDA is modified by incorporating simplified joint shear strength degradation.Based on the modified DDA,the kinematics of the Baige landslide that occurred along the Jinsha River in China on 10 October 2018 are reproduced.The violent starting velocity of the landslide is considered explicitly.Three cases with different violent starting velocities are investigated to show their effect on the landslide movement process.Subsequently,the landslide movement process and the final accumulation characteristics are analyzed from multiple perspectives.The results show that the violent starting velocity affects the landslide motion characteristics,which is found to be about 4 m/s in the Baige landslide.The movement process of the Baige landslide involves four stages:initiation,high-speed sliding,impact-climbing,low-speed motion and accumulation.The accumulation states of sliding masses in different zones are different,which essentially corresponds to reality.The research results suggest that the modified DDA is applicable to similar high-level rock landslides.
基金supported by the National Natural Science Foundation of China(Nos.52208369,52309138,52209142,51978666)the Department of Science and Technology of Sichuan Province(2023NSFSC0284).
文摘In practical engineering,due to the noncontinuity characteristics of joints in rock slopes,in addition to plane failure,stepped sliding failure may occur for intermittently jointed rock slopes.Especially for intermittently bedding jointed rock slopes,the correlation and difference in strength parameters between joints and rock bridges,along with the various failure modes and intermittency of rock bridges,contribute to the complexity of stepped failure modes and the unpredictability of failure regions.Based on the upper-bound limit analysis method and multi-sliders step-path failure mode,considering the shear and tensile failure of rock bridges and the weakened relationship between the strength parameters of rock bridges and jointed surfaces,by introducing the modified M-C failure criterion and the formula for calculating the energy consumption of tensile failure of rock bridges,two failure mechanisms are constructed to obtain the safety factor(F_(s))of intermittently jointed rock slopes.The sequential quadratic programming method is used to obtain the optimal upper-bound solution for F_(s).The influence of multiple key parameters(slope height H,horizontal distance L,Slope angleβ,shear strength parameters of the rock bridgeφr and cr,Dimensionless parameter u,weakening coefficients of the internal friction angle and cohesion between the rock bridges and joint surfaces Kφand Kc)on the stability analysis of intermittently jointed rock slopes under the shear failure mode of rock bridges as well as under the tensile failure mode is also explored.The reliability of the failure mechanisms is verified by comparative analysis with theoretical results,numerical results,and landslide cases,and the variation rules of F_(s)with each key parameter are obtained.The results show that F_(s) varies linearly withφr and cr of the rock bridge and with K_(φ)and K_(c),whereas F_(s)changes nonlinearly with H and L.In particular,with the increase in Kφand Kc,Fs increases by approximately 52.78%and 171.02%on average,respectively.For rock bridge tensile failure,F_(s) shows a nonlinearly positive correlation withφr,cr,Kφand Kc.In particular,with the increase in Kφand Kc,Fs increases by approximately 13%and 61.69%on average,respectively.Fs decreases rapidly with increasing slope gradientβand decreasing dimensionless parameterμ.When Kφand Kc are both less than 1.0,the stepped sliding surface occurs more easily than the plane failure surface,especially in the case of tensile failure of the rock bridge.In addition,rock slopes with higher strength parameters,taller heights,and greater weakening coefficients are prone to rock bridge tension failure with lower Fs,and more attention should be given to the occurrence of such accidents in actual engineering.
文摘为研究乳清多肽(whey protein hydrolysates,WPH)对反复冻融猪肉糜氧化和品质的影响规律及机理,本实验将不同质量分数(5%、10%、15%)WPH添加到生猪肉糜中,进行不同冻融循环(0~9)处理,检测冻融后肉糜解冻损失、硫代巴比妥酸(thiobarbituricacid reactive substances,TBARS)值、挥发性盐基氮(total volatile base nitrogen,TVB-N)值、质构特性、流变学模量损耗、蛋白羰基含量以及拉曼光谱的变化情况。结果表明,未经冻融时,样品组与空白组各指标之间都无明显差异(P>0.05)。冻融处理后,猪肉糜的解冻损失率由2.67%~2.93%升高至7.00%~12.4%,其中15%WPH明显抑制了解冻损失的增加(P<0.05),提高了肉糜保水性。当冻融循环达到7~9次后,添加15%WPH组抑制肉糜TVB-N值、TBARS值以及羰基含量升高均比空白组和未水解乳清多肽组效果好(P<0.05)。在质构方面,随着冻融次数的增加,猪肉糜硬度、弹性、内聚性和咀嚼性均呈现明显的下降趋势。冻融9次时,15%WPH可使猪肉糜咀嚼性从9.63 g升高到17 g;冻融5次时,15%WPH组的弹性高达到0.69,超过丁基羟基茴香醚(butylatedhydroxyanisole,BHA)阳性空白组;WPH组和BHA组的硬度和内聚性均显著高于空白组;不同添加量WPH对猪肉糜质构都有改善作用,其中高剂量组效果最好。流变学结果显示,WPH组猪肉糜损耗模量G’’降低比较明显。拉曼光谱表明,添加15%WPH有效抑制了冻融循环过程中肉蛋白α-螺旋含量下降、β-折叠含量上升的现象,保护了蛋白质二级结构。实验表明,在冻融循环过程中,WPH起到抑制猪肉糜氧化和改善产品品质的作用。
