The deep rock mass within coal mines situated in a challenging environment are characterized by high ground stress,high geotemperature,high osmotic water pressure,and dynamic disturbances from mechanical excavation.To...The deep rock mass within coal mines situated in a challenging environment are characterized by high ground stress,high geotemperature,high osmotic water pressure,and dynamic disturbances from mechanical excavation.To investigate the impact of this complex mechanical environment on the dynamic characteristics of roof sandstone in self-formed roadways without coal pillars,standard specimens of deep sandstone from the 2611 upper tunnel working face of the Yongmei Company within the Henan Coal Chemical Industry Group in Henan,China were prepared,and an orthogonal test was designed.Using a self-developed geotechnical dynamic impact mechanics test system,triaxial dynamic impact tests under thermal-hydraulicmechanical coupling conditions were conducted on deep sandstone.The results indicate that under high confining pressure,deep sandstone exhibits pronounced brittle failure at low temperatures,with peak strength gradually decreasing as temperature and osmotic water pressure increase.Conversely,under low confining pressure and low temperature,the brittleness of deep sandstone weakens gradually,while ductility increases.Moreover,sandstone demonstrates higher peak strength at low temperatures under high axial pressure conditions,lower peak strength at high temperatures,and greater strain under low axial pressure and high osmotic water pressure.Increases in impact air pressure and osmotic water pressure have proportionally greater effects on peak stress and peak strain.Approximately 50%of the input strain energy is utilized as effective energy driving the sandstone fracture process.Polar analysis identifies the optimal combination of factors affecting the peak stress and peak strain of sandstone.Under the coupling effect,intergranular and transgranular fractures occur within the sandstone.SEM images illustrate that the damage forms range from minor damage with multiple fissures to extensive fractures and severe fragmentation.This study elucidates the varied dynamic impact mechanical properties of deep sandstones under thermal-hydraulic-mechanical coupling,along with multifactor analysis methods and their optimal factor combinations.展开更多
为研究典型粉砂地层地铁深基坑周边地表沉降变化规律,以杭州地区数十个地铁深基坑工程为例,通过实测数据分析基坑周边地表沉降及水平位移的变化规律,推导出粉砂地层地铁深基坑周边地表沉降预测模型。研究结果表明:基坑周边地表最大沉降...为研究典型粉砂地层地铁深基坑周边地表沉降变化规律,以杭州地区数十个地铁深基坑工程为例,通过实测数据分析基坑周边地表沉降及水平位移的变化规律,推导出粉砂地层地铁深基坑周边地表沉降预测模型。研究结果表明:基坑周边地表最大沉降均值为1.77‰H e(H e为基坑开挖深度),最大沉降主要发生在墙后距离0.35 H e~1.08 H e;基坑最大水平位移平均值为2.73‰H e,最大位移深度为0.7 H e~1.2 H e;基坑周边地表最大沉降约为最大水平位移的0.75~1.21倍;地连墙插入比平均值为1.45,插入比大小与基坑水平位移量和周边地表沉降量呈负相关。进而由基坑周边地表沉降和水平位移的统计分析结果,推导正态和偏态分布密度函数下的基坑周边地表沉降预测公式,并与实测结果进行对比,发现偏态分布密度函数下的预测方法更合理。这可为类似地层条件下的基坑周边地表沉降预测提供理论依据和工程指导。展开更多
为探究"三高一扰动"特殊环境下切顶卸压无煤柱自成巷顶板砂岩切缝的动态力学性能,利用自主设计的岩土体动态冲击力学试验系统,对粉砂岩进行不同热–水–力耦合条件下的冲击压缩试验,研究动态应力–应变特征、动变形模量与加...为探究"三高一扰动"特殊环境下切顶卸压无煤柱自成巷顶板砂岩切缝的动态力学性能,利用自主设计的岩土体动态冲击力学试验系统,对粉砂岩进行不同热–水–力耦合条件下的冲击压缩试验,研究动态应力–应变特征、动变形模量与加载率关系、以及加载率、轴压、围压、渗透水压、温度、吸收能与峰值应力和峰值应变的动态力学性能,利用扫描电镜(Scanning Electron Microscopy,SEM)研究粉砂岩试样断口面微观结构。研究结果表明:(1)在不同的动荷载作用下,粉砂岩试样的峰值应力和峰值应变均随轴压、围压、渗透水压、温度的升高而不断增大,脆性逐渐减弱而延性逐渐增强,变形破坏总体分为压密、弹性变形、塑性变形和破坏4个阶段;(2)动变形模量随着加载率的增大呈现出先增大后减小的发展趋势,动变形模量136GPa左右为一个临界阈值;(3)轴压、围压、水和温度对砂岩在热–水–力耦合特定环境下的动态冲击力学性能具有一定的增强效应;(4)随着峰值应变的增加,粉砂岩试样的吸收能呈线性增加趋势,其破碎变形与吸收能呈正相关。展开更多
基金supported by the Science and Technology Commissioner Project of Zhejiang Province(2023ST04)the supporting funds for scientific research launch of Zhejiang University of Science and Technology(F701104M11).
文摘The deep rock mass within coal mines situated in a challenging environment are characterized by high ground stress,high geotemperature,high osmotic water pressure,and dynamic disturbances from mechanical excavation.To investigate the impact of this complex mechanical environment on the dynamic characteristics of roof sandstone in self-formed roadways without coal pillars,standard specimens of deep sandstone from the 2611 upper tunnel working face of the Yongmei Company within the Henan Coal Chemical Industry Group in Henan,China were prepared,and an orthogonal test was designed.Using a self-developed geotechnical dynamic impact mechanics test system,triaxial dynamic impact tests under thermal-hydraulicmechanical coupling conditions were conducted on deep sandstone.The results indicate that under high confining pressure,deep sandstone exhibits pronounced brittle failure at low temperatures,with peak strength gradually decreasing as temperature and osmotic water pressure increase.Conversely,under low confining pressure and low temperature,the brittleness of deep sandstone weakens gradually,while ductility increases.Moreover,sandstone demonstrates higher peak strength at low temperatures under high axial pressure conditions,lower peak strength at high temperatures,and greater strain under low axial pressure and high osmotic water pressure.Increases in impact air pressure and osmotic water pressure have proportionally greater effects on peak stress and peak strain.Approximately 50%of the input strain energy is utilized as effective energy driving the sandstone fracture process.Polar analysis identifies the optimal combination of factors affecting the peak stress and peak strain of sandstone.Under the coupling effect,intergranular and transgranular fractures occur within the sandstone.SEM images illustrate that the damage forms range from minor damage with multiple fissures to extensive fractures and severe fragmentation.This study elucidates the varied dynamic impact mechanical properties of deep sandstones under thermal-hydraulic-mechanical coupling,along with multifactor analysis methods and their optimal factor combinations.
文摘为研究典型粉砂地层地铁深基坑周边地表沉降变化规律,以杭州地区数十个地铁深基坑工程为例,通过实测数据分析基坑周边地表沉降及水平位移的变化规律,推导出粉砂地层地铁深基坑周边地表沉降预测模型。研究结果表明:基坑周边地表最大沉降均值为1.77‰H e(H e为基坑开挖深度),最大沉降主要发生在墙后距离0.35 H e~1.08 H e;基坑最大水平位移平均值为2.73‰H e,最大位移深度为0.7 H e~1.2 H e;基坑周边地表最大沉降约为最大水平位移的0.75~1.21倍;地连墙插入比平均值为1.45,插入比大小与基坑水平位移量和周边地表沉降量呈负相关。进而由基坑周边地表沉降和水平位移的统计分析结果,推导正态和偏态分布密度函数下的基坑周边地表沉降预测公式,并与实测结果进行对比,发现偏态分布密度函数下的预测方法更合理。这可为类似地层条件下的基坑周边地表沉降预测提供理论依据和工程指导。
文摘为探究"三高一扰动"特殊环境下切顶卸压无煤柱自成巷顶板砂岩切缝的动态力学性能,利用自主设计的岩土体动态冲击力学试验系统,对粉砂岩进行不同热–水–力耦合条件下的冲击压缩试验,研究动态应力–应变特征、动变形模量与加载率关系、以及加载率、轴压、围压、渗透水压、温度、吸收能与峰值应力和峰值应变的动态力学性能,利用扫描电镜(Scanning Electron Microscopy,SEM)研究粉砂岩试样断口面微观结构。研究结果表明:(1)在不同的动荷载作用下,粉砂岩试样的峰值应力和峰值应变均随轴压、围压、渗透水压、温度的升高而不断增大,脆性逐渐减弱而延性逐渐增强,变形破坏总体分为压密、弹性变形、塑性变形和破坏4个阶段;(2)动变形模量随着加载率的增大呈现出先增大后减小的发展趋势,动变形模量136GPa左右为一个临界阈值;(3)轴压、围压、水和温度对砂岩在热–水–力耦合特定环境下的动态冲击力学性能具有一定的增强效应;(4)随着峰值应变的增加,粉砂岩试样的吸收能呈线性增加趋势,其破碎变形与吸收能呈正相关。
