泡沫轻质土在公路路基上应用广泛,但尚未在高速铁路路基上应用。提出一种泡沫轻质土的高速铁路新型减振路基材料。通过对其密度,强度,应力应变特性进行深入探究,结合单轴压缩试验,研究不同养护龄期下的泡沫轻质土湿密度对抗压强度的影...泡沫轻质土在公路路基上应用广泛,但尚未在高速铁路路基上应用。提出一种泡沫轻质土的高速铁路新型减振路基材料。通过对其密度,强度,应力应变特性进行深入探究,结合单轴压缩试验,研究不同养护龄期下的泡沫轻质土湿密度对抗压强度的影响。采用有限元软件建立传统材料和新型材料下的高速铁路路基模型,通过室内试验和资料调研得到材料参数,梁-弹性半空间模型模拟列车移动荷载,并将泡沫轻质土与传统路基材料在高速铁路路基上应用时分别产生的动响应进行对比研究。结果表明,泡沫轻质土的抗压强度与湿密度之间具有良好的相关性,抗压强度随着养护龄期的增长而增大,且早期增长较快,后期增速逐渐降低。相对于传统路基,新型路基基床表层、基床填土和地基基础的动应力都有一定程度的减弱,其中基床表层和基床填土的减振能力最为明显,消减幅度分别为3.75 k Pa和2 k Pa,地基基础相对减振0.78 k Pa。但在基床底层减振方面,传统路基材料反而比新型路基材料在基床底层上减振3.5 k Pa,故不建议将新型材料应用于基床底层。综上,泡沫轻质土在高速铁路路基领域具备很大的发展潜力,研究成果可为高速铁路路基的进一步减振研究提供参考。展开更多
In order to have a good understanding of the behavior of wet shotcrete as a support element interacting with the rock mass,mechanism of wet shotcrete interacting with rock in support systems was analyzed through theor...In order to have a good understanding of the behavior of wet shotcrete as a support element interacting with the rock mass,mechanism of wet shotcrete interacting with rock in support systems was analyzed through theoretical,numerical study and analytical analysis.A new model of distribution of rock stress state after wet shotcrete was applied,which includes shotcrete layer,composite layer,strengthening layer,plastic layer and elastic layer,and a full illustration of the rock mass stress state was given after shotcrete interacting with rock mass.At the same time,numerical analysis with FLAC gives a stress distribution along the monitor line,respectively,at the sidewall and roof of the tunnel.The displacement obviously decreases with the depth of rock,the tangential stress for tunnel supported by shotcrete is lower than that without shotcrete,and radial stress for tunnel supported by shotcrete is higher than that without shotcrete.It has been demonstrated by AIRY'S stress function,which gives a reasonable solution.Finally,the application of wet shotcrete in Jinfeng Gold Mine shows that the displacement of tunnel decreases obviously in sidewall and roof.展开更多
Ti-6Al-4V alloy was processed by wet shot peening with ceramic beads. The effects of the shot peened intensity on the microstructure, surface morphology, and residual stress were investigated. A tensile-tensile fatigu...Ti-6Al-4V alloy was processed by wet shot peening with ceramic beads. The effects of the shot peened intensity on the microstructure, surface morphology, and residual stress were investigated. A tensile-tensile fatigue test was performed and the fracture mechanism was proposed. The results demonstrate that the surface roughness after wet shot peening is obviously lower than that after dry shot peening. With the increase of the shot peened intensity, the depth of the residual stress layer increases to 250 ktrn, and the maximum stress in this layer increases to -895 MPa. The fatigue strength also increases by 12.4% because of the wet shot peening treatment. The dislocation density of the surface layer is significantly enhanced after the wet shot peening with ceramic beads. The microstructure of the surface layer is obviously refined into ultra-fine grains.展开更多
A modified surface layer was formed on Ti-6Al-4V alloy by wet peening treatment. The variations of the residual stress,nano-hardness and microstructure of the modified layer with depth from surface were studied using ...A modified surface layer was formed on Ti-6Al-4V alloy by wet peening treatment. The variations of the residual stress,nano-hardness and microstructure of the modified layer with depth from surface were studied using X-ray diffraction analysis,nano-indentation analysis, scanning electron microscopy and transmission electron microscopy observations. The results show thatboth the compressive residual stress and hardness decrease with increasing depth, and the termination depths are 160 and 80 μm,respectively. The microstructure observation indicates that within 80 μm, the compressive residual stress and the hardness areenhanced by the co-action of the grain refinement strengthening and dislocation strengthening. Within 80–160 μm, the compressiveresidual stress mainly derives from the dislocation strengthening. The strengthened layer in Ti-6Al-4V alloy after wet peeningtreatment was quantitatively analyzed by a revised equation with respect to a relation between hardness and yield strength.展开更多
目前我国井下混凝土喷浆机多为转子式结构,以风力输送混料进行干喷工艺,但干喷存在混凝土喷射期间粉尘浓度大、回弹率高等问题。为了解决干式喷浆工艺存在的喷浆料回弹率高、作业空间粉尘量大、劳动效率低、喷浆材料混合不均匀、混凝土...目前我国井下混凝土喷浆机多为转子式结构,以风力输送混料进行干喷工艺,但干喷存在混凝土喷射期间粉尘浓度大、回弹率高等问题。为了解决干式喷浆工艺存在的喷浆料回弹率高、作业空间粉尘量大、劳动效率低、喷浆材料混合不均匀、混凝土强度低等问题,减少现场作业人员尘肺病的发生,改善劳动作业环境,优化喷浆料的混合效果,对比目前国内外的喷浆机特性,以山西汾西中兴煤业四采区瓦斯治理底板岩巷为背景,开发了一套无轴双螺旋湿式混凝土喷浆机,并对无轴双螺旋搅拌装置进行数值模拟试验研究,该无轴双螺旋搅拌装置为喷浆材料与水充分发生水化反应提供了技术保障。通过现场试验,喷浆作业区域粉尘浓度在8~10 mg/m 3,湿式混凝土喷浆机喷射能力8 m 3/h,相比较普通干式喷浆机,采用湿式喷浆机所制备的混凝土强度提高65%。实践表明,使用无轴双螺旋搅拌机构的湿式混凝土喷浆机在提高喷浆效率、强化围岩应力状态、改善工人作业环境等方面有改善明显。展开更多
文摘泡沫轻质土在公路路基上应用广泛,但尚未在高速铁路路基上应用。提出一种泡沫轻质土的高速铁路新型减振路基材料。通过对其密度,强度,应力应变特性进行深入探究,结合单轴压缩试验,研究不同养护龄期下的泡沫轻质土湿密度对抗压强度的影响。采用有限元软件建立传统材料和新型材料下的高速铁路路基模型,通过室内试验和资料调研得到材料参数,梁-弹性半空间模型模拟列车移动荷载,并将泡沫轻质土与传统路基材料在高速铁路路基上应用时分别产生的动响应进行对比研究。结果表明,泡沫轻质土的抗压强度与湿密度之间具有良好的相关性,抗压强度随着养护龄期的增长而增大,且早期增长较快,后期增速逐渐降低。相对于传统路基,新型路基基床表层、基床填土和地基基础的动应力都有一定程度的减弱,其中基床表层和基床填土的减振能力最为明显,消减幅度分别为3.75 k Pa和2 k Pa,地基基础相对减振0.78 k Pa。但在基床底层减振方面,传统路基材料反而比新型路基材料在基床底层上减振3.5 k Pa,故不建议将新型材料应用于基床底层。综上,泡沫轻质土在高速铁路路基领域具备很大的发展潜力,研究成果可为高速铁路路基的进一步减振研究提供参考。
基金Project(50934002) supported by the National Natural Science Foundation of China
文摘In order to have a good understanding of the behavior of wet shotcrete as a support element interacting with the rock mass,mechanism of wet shotcrete interacting with rock in support systems was analyzed through theoretical,numerical study and analytical analysis.A new model of distribution of rock stress state after wet shotcrete was applied,which includes shotcrete layer,composite layer,strengthening layer,plastic layer and elastic layer,and a full illustration of the rock mass stress state was given after shotcrete interacting with rock mass.At the same time,numerical analysis with FLAC gives a stress distribution along the monitor line,respectively,at the sidewall and roof of the tunnel.The displacement obviously decreases with the depth of rock,the tangential stress for tunnel supported by shotcrete is lower than that without shotcrete,and radial stress for tunnel supported by shotcrete is higher than that without shotcrete.It has been demonstrated by AIRY'S stress function,which gives a reasonable solution.Finally,the application of wet shotcrete in Jinfeng Gold Mine shows that the displacement of tunnel decreases obviously in sidewall and roof.
基金Project(NCET-10-0278)supported by Program for New Century Excellent Talents in University,China
文摘Ti-6Al-4V alloy was processed by wet shot peening with ceramic beads. The effects of the shot peened intensity on the microstructure, surface morphology, and residual stress were investigated. A tensile-tensile fatigue test was performed and the fracture mechanism was proposed. The results demonstrate that the surface roughness after wet shot peening is obviously lower than that after dry shot peening. With the increase of the shot peened intensity, the depth of the residual stress layer increases to 250 ktrn, and the maximum stress in this layer increases to -895 MPa. The fatigue strength also increases by 12.4% because of the wet shot peening treatment. The dislocation density of the surface layer is significantly enhanced after the wet shot peening with ceramic beads. The microstructure of the surface layer is obviously refined into ultra-fine grains.
基金Project(51405059)supported by the National Natural Science Foundation of ChinaProject(2014M551074)supported by the China Postdoctoral Science FoundationProject(NCET-10-0278)supported by the Program for New Century Excellent Talents in University
文摘A modified surface layer was formed on Ti-6Al-4V alloy by wet peening treatment. The variations of the residual stress,nano-hardness and microstructure of the modified layer with depth from surface were studied using X-ray diffraction analysis,nano-indentation analysis, scanning electron microscopy and transmission electron microscopy observations. The results show thatboth the compressive residual stress and hardness decrease with increasing depth, and the termination depths are 160 and 80 μm,respectively. The microstructure observation indicates that within 80 μm, the compressive residual stress and the hardness areenhanced by the co-action of the grain refinement strengthening and dislocation strengthening. Within 80–160 μm, the compressiveresidual stress mainly derives from the dislocation strengthening. The strengthened layer in Ti-6Al-4V alloy after wet peeningtreatment was quantitatively analyzed by a revised equation with respect to a relation between hardness and yield strength.
文摘目前我国井下混凝土喷浆机多为转子式结构,以风力输送混料进行干喷工艺,但干喷存在混凝土喷射期间粉尘浓度大、回弹率高等问题。为了解决干式喷浆工艺存在的喷浆料回弹率高、作业空间粉尘量大、劳动效率低、喷浆材料混合不均匀、混凝土强度低等问题,减少现场作业人员尘肺病的发生,改善劳动作业环境,优化喷浆料的混合效果,对比目前国内外的喷浆机特性,以山西汾西中兴煤业四采区瓦斯治理底板岩巷为背景,开发了一套无轴双螺旋湿式混凝土喷浆机,并对无轴双螺旋搅拌装置进行数值模拟试验研究,该无轴双螺旋搅拌装置为喷浆材料与水充分发生水化反应提供了技术保障。通过现场试验,喷浆作业区域粉尘浓度在8~10 mg/m 3,湿式混凝土喷浆机喷射能力8 m 3/h,相比较普通干式喷浆机,采用湿式喷浆机所制备的混凝土强度提高65%。实践表明,使用无轴双螺旋搅拌机构的湿式混凝土喷浆机在提高喷浆效率、强化围岩应力状态、改善工人作业环境等方面有改善明显。
