连通率对不同倾角结构面岩样的力学特性和破坏机制有显著的影响。因此,人工制备了连通率k为0、0.25、0.50、1.00,倾角β为15°、30°、45°、60°的结构面岩样,并利用单轴压缩试验和围压为200、400、600 k Pa的三轴压...连通率对不同倾角结构面岩样的力学特性和破坏机制有显著的影响。因此,人工制备了连通率k为0、0.25、0.50、1.00,倾角β为15°、30°、45°、60°的结构面岩样,并利用单轴压缩试验和围压为200、400、600 k Pa的三轴压缩试验来探讨连通率对岩体的力学特性影响。结果表明:(1)连通率对岩体造成的劣化效应显著,随着连通率的增加,其峰值强度呈下降趋势。当连通率k≤0.50时,应力-应变曲线均表现为先应变硬化再应变软化趋势;当连通率k>0.50,应力-应变由低角度的应变软化向高角度的应变硬化转变。(2)结构面岩样的体变均表现为先体缩再体胀。各倾角下,随着连通率的增大,体胀逐渐减小呈规律性排列;当连通率k=1.00,倾角β为30°、45°和60°时,岩样在体缩过程中发生了突变。(3)在能量拐点a之前,耗散能U_d随着连通率的增大而增大,弹性应变能U_(e)随着连通率的增大略微降低;在能量拐点a之后,耗散能U_(d)和弹性应变能U_(e)都急剧增加,不同连通率的能量释放速率大致相当。(4)对不同连通率岩样的预测判据进行了分类,当k<0.5时,β=45。+φ_(j)2适用于判断破坏角度,其中,φ_(j)为结构面内摩擦角;当k≥0.5时,改进的Jaeger判据能准确地反映岩体破坏角度。展开更多
Chloride ions(Cl^(-))have been shown to impact the long-lasting nature of reinforced concrete.However,Cl^(-)that are already bound inside the concrete will not lead to the deterioration of the concrete’s characterist...Chloride ions(Cl^(-))have been shown to impact the long-lasting nature of reinforced concrete.However,Cl^(-)that are already bound inside the concrete will not lead to the deterioration of the concrete’s characteristics.The composition of the cement-based material,including the type of cement and auxiliary materials,greatly influences the ability of the material to bind Cl^(-),and varied components result in varying binding beha-vior of the Cl^(-).Simultaneously,the Cl^(-)binding process in concrete is influenced by both the internal and exterior surroundings,as well as the curing practices.These factors impact the hydration process of the cement and the internal pore structure of the concrete.Currently,mathematical theories and molecular dynamics simulations have increasingly been employed as the prevalent methods for examining the binding behaviors of Cl^(-)in concrete.These techniques are extensively utilized for predicting the lifespan and conducting microscopic studies of reinforced concrete in Cl^(-)settings.This work proposes recommendations for future research based on a summary of experimental and simulation investigations on Cl^(-)binding.Which will offer theoretical guidance for studying the binding of Cl^(-)in cement-based materials.展开更多
为探讨香梨节水灌溉模式,提高水分利用效率(water use efficiency,WUE)和产量,于2021–2022年在新疆29团5年生香梨园开展灌溉方式和灌溉定额双因素完全随机试验,设置了3种微灌方式:地表滴灌(M1)、地下滴灌(M2)、根区渗灌(M3),3种灌溉定...为探讨香梨节水灌溉模式,提高水分利用效率(water use efficiency,WUE)和产量,于2021–2022年在新疆29团5年生香梨园开展灌溉方式和灌溉定额双因素完全随机试验,设置了3种微灌方式:地表滴灌(M1)、地下滴灌(M2)、根区渗灌(M3),3种灌溉定额:低水(I1)、中水(I2)、高水(I3),以传统漫灌(CK)为对照,研究不同灌溉方式和灌溉量对土壤电导率和脱盐率、香梨生长、产量、WUE、果实品质和净效益的影响。结果表明:M2的产量和WUE最高,且可以促进香梨生长,提高果实品质以及促进盐分淋洗。M3前期的投入成本最大,但获得的净利润仅次于M2。灌溉方式相同时,增加灌溉定额有利于香梨生长、提高产量和盐分淋洗。基于主成分分析、优劣解距离法和秩和比法3种综合评价方法从环境效益、果实品质和经济效益3个方面,选取15个评价指标进行综合评价,M2I3处理综合得分最高,M1I1处理综合得分最低。因此,对矮化密植初果期的香梨进行灌溉时,推荐地下滴灌模式且生育期灌溉定额为6 750 m^(3)/hm^(2)。研究可为南疆干旱区林果业节水控盐高效生产提供理论依据和技术支撑。展开更多
文摘连通率对不同倾角结构面岩样的力学特性和破坏机制有显著的影响。因此,人工制备了连通率k为0、0.25、0.50、1.00,倾角β为15°、30°、45°、60°的结构面岩样,并利用单轴压缩试验和围压为200、400、600 k Pa的三轴压缩试验来探讨连通率对岩体的力学特性影响。结果表明:(1)连通率对岩体造成的劣化效应显著,随着连通率的增加,其峰值强度呈下降趋势。当连通率k≤0.50时,应力-应变曲线均表现为先应变硬化再应变软化趋势;当连通率k>0.50,应力-应变由低角度的应变软化向高角度的应变硬化转变。(2)结构面岩样的体变均表现为先体缩再体胀。各倾角下,随着连通率的增大,体胀逐渐减小呈规律性排列;当连通率k=1.00,倾角β为30°、45°和60°时,岩样在体缩过程中发生了突变。(3)在能量拐点a之前,耗散能U_d随着连通率的增大而增大,弹性应变能U_(e)随着连通率的增大略微降低;在能量拐点a之后,耗散能U_(d)和弹性应变能U_(e)都急剧增加,不同连通率的能量释放速率大致相当。(4)对不同连通率岩样的预测判据进行了分类,当k<0.5时,β=45。+φ_(j)2适用于判断破坏角度,其中,φ_(j)为结构面内摩擦角;当k≥0.5时,改进的Jaeger判据能准确地反映岩体破坏角度。
文摘Chloride ions(Cl^(-))have been shown to impact the long-lasting nature of reinforced concrete.However,Cl^(-)that are already bound inside the concrete will not lead to the deterioration of the concrete’s characteristics.The composition of the cement-based material,including the type of cement and auxiliary materials,greatly influences the ability of the material to bind Cl^(-),and varied components result in varying binding beha-vior of the Cl^(-).Simultaneously,the Cl^(-)binding process in concrete is influenced by both the internal and exterior surroundings,as well as the curing practices.These factors impact the hydration process of the cement and the internal pore structure of the concrete.Currently,mathematical theories and molecular dynamics simulations have increasingly been employed as the prevalent methods for examining the binding behaviors of Cl^(-)in concrete.These techniques are extensively utilized for predicting the lifespan and conducting microscopic studies of reinforced concrete in Cl^(-)settings.This work proposes recommendations for future research based on a summary of experimental and simulation investigations on Cl^(-)binding.Which will offer theoretical guidance for studying the binding of Cl^(-)in cement-based materials.
文摘为探讨香梨节水灌溉模式,提高水分利用效率(water use efficiency,WUE)和产量,于2021–2022年在新疆29团5年生香梨园开展灌溉方式和灌溉定额双因素完全随机试验,设置了3种微灌方式:地表滴灌(M1)、地下滴灌(M2)、根区渗灌(M3),3种灌溉定额:低水(I1)、中水(I2)、高水(I3),以传统漫灌(CK)为对照,研究不同灌溉方式和灌溉量对土壤电导率和脱盐率、香梨生长、产量、WUE、果实品质和净效益的影响。结果表明:M2的产量和WUE最高,且可以促进香梨生长,提高果实品质以及促进盐分淋洗。M3前期的投入成本最大,但获得的净利润仅次于M2。灌溉方式相同时,增加灌溉定额有利于香梨生长、提高产量和盐分淋洗。基于主成分分析、优劣解距离法和秩和比法3种综合评价方法从环境效益、果实品质和经济效益3个方面,选取15个评价指标进行综合评价,M2I3处理综合得分最高,M1I1处理综合得分最低。因此,对矮化密植初果期的香梨进行灌溉时,推荐地下滴灌模式且生育期灌溉定额为6 750 m^(3)/hm^(2)。研究可为南疆干旱区林果业节水控盐高效生产提供理论依据和技术支撑。
