The present technical paper outlines the details of the controlled blasting techniques used to optimize blasting pattern for excavation of hard rock near the Bhira Earthen Dam in Maharashtra,India.In this connection,a...The present technical paper outlines the details of the controlled blasting techniques used to optimize blasting pattern for excavation of hard rock near the Bhira Earthen Dam in Maharashtra,India.In this connection,a series of experimental blasts were conducted by adjusting various blast design parameters at project site.The safe charge weight per delay was kept between 0.125 and 0.375 kg.The outcomes of these experimental blasts were analyzed to recommend optimized blasting patterns and methods for the overall excavation process during actual blasting operations.Blast design parameters,including the maximum quantity of explosive per delay,hole depth,burden and spacing between holes were optimized by using a site-specific attenuation equation,taking into account the proximity of the dam and tunnel from the blasting area.Peak particle velocity(PPV)level of 10 mm/s and 50 mm/s respectively were adopted as the safe vibration level for ensuring safety of the Bhira Earthen Dam and the nearby tunnel from the adverse effects of blast vibrations by analyzing the dominant frequency of ground vibrations observed and also by reviewing various international standards.Frequency of the ground vibrations observed on the dam and tunnel from majority of the blasts was found to be more than 10 Hz and 50 Hz respectively.During the entire period of blasting,the blast vibrations were recorded to be far lower than the safe vibration level set for these structures.Maximum Vibration level of about 0.8 mm/s and 35 mm/s were observed on dam and tunnel respectively which are far lower than the safe vibration level adopted for these structures.Hence,the entire excavation work was completed successfully and safely,without endangering the safety of dam or tunnel.展开更多
为研究颗粒阻尼器布置方案对多层结构减震性能的影响,制作了缩尺比为1/5的三层钢框架模型结构,进行了5条天然波下的地震模拟振动台试验,研究并联式单向单颗粒阻尼器(Parallel Single-dimensional Single Particle Damper,PSSPD)的减震...为研究颗粒阻尼器布置方案对多层结构减震性能的影响,制作了缩尺比为1/5的三层钢框架模型结构,进行了5条天然波下的地震模拟振动台试验,研究并联式单向单颗粒阻尼器(Parallel Single-dimensional Single Particle Damper,PSSPD)的减震控制效果。基于试验获得的模型自振频率、阻尼比等动力特性设计3种PSSPD布置方案,分析不同布置方案下模型结构的试验现象及位移和加速度响应。试验结果表明:PSSPD对结构响应峰值减震率可达到43.43%,均方根减震率可达到38.18%,其对多层结构具有良好的减震控制效果;PSSPD对结构均方根的平均减震效果要优于对峰值的平均减震效果;PSSPD布置方案对其减震效果影响显著,且其减震性能与本身参数、受控结构振动特性、地震动参数之间的耦合关系复杂。最后,建立PSSPD在任意布置方案下受控结构的力学模型,提出其数值分析流程。数值计算结果和试验结果在位移峰值及均方根方面具有良好的吻合度。展开更多
传统单颗粒阻尼器存在颗粒半径过大、空间占用率高等局限,多颗粒阻尼器存在启振条件苛刻、动量交换效率低等不足。为提升颗粒阻尼器的减震性能,提出将叠层式单颗粒阻尼器(stacked single particle damper, SSPD),并将其与齿轮齿条惯容...传统单颗粒阻尼器存在颗粒半径过大、空间占用率高等局限,多颗粒阻尼器存在启振条件苛刻、动量交换效率低等不足。为提升颗粒阻尼器的减震性能,提出将叠层式单颗粒阻尼器(stacked single particle damper, SSPD),并将其与齿轮齿条惯容装置相结合,进而形成叠层式单颗粒惯容减振系统(stacked single particle-inerter damping system, SSPIS)。在深入分析颗粒各阶段受力状态的基础上,剖析SSPIS减振机理,构建SSPIS-结构系统力学模型,并提出该力学模型的数值模拟流程。为验证SSPIS理论力学模型与数值模拟分析流程的准确性,并探究SSPIS对受控结构的真实减震控制效果,制作钢框架模型结构,完成地震模拟振动台试验。动力试验与理论结果表明:将惯容装置布置于SSPD中可显著提升颗粒与结构的动量交换效率,增大其表观质量与耗能能力,拓宽SSPIS的减振频带。相较于传统颗粒阻尼器,SSPIS在各类场地地震作用下均可对受控结构产生良好的控制效果,具有良好的工程应用前景。展开更多
在被动控制装置中,经典调谐质量阻尼器(tuned mass damper,TMD)是应用最为广泛的。然而经典TMD在实际安装使用中往往需要较大的附加质量和较大的安装空间,给实际应用带来不便。旋转惯性双调谐质量阻尼器(rotational inertia double tune...在被动控制装置中,经典调谐质量阻尼器(tuned mass damper,TMD)是应用最为广泛的。然而经典TMD在实际安装使用中往往需要较大的附加质量和较大的安装空间,给实际应用带来不便。旋转惯性双调谐质量阻尼器(rotational inertia double tuned mass damper,RIDTMD)是一种新型的、高效的振动控制装置,它利用了惯容的表观质量增效功能,以及调谐质量和调谐惯容的双重调谐效果,具有较好的减振性能和轻量化控制的特性。然而,当考虑到RIDTMD对基础激励下的主结构控制进行优化设计时,目前的设计方法基本为数值法,不便应用。为解决上述问题,基于H2优化理论,以主结构位移均方根值为目标函数,推导了RIDTMD减震系统的参数解析设计公式。在解析公式的基础上,通过频域和时域两种数值仿真方法分析了RIDTMD的减震性能和轻量化效果,验证了解析公式的准确性和适用性。仿真结果表明:在频域中,RIDTMD对主结构位移频响峰值控制和减震带宽均优于TMD,并具备轻量化和工作行程小的优势;在时域中,以5 MW陆上风机为例,在实际地震波激励作用下,RIDTMD对塔筒一阶纵弯的均方根值和峰值减震均优于TMD,在相同性能指标下能实现较好的轻量化效果。展开更多
文摘The present technical paper outlines the details of the controlled blasting techniques used to optimize blasting pattern for excavation of hard rock near the Bhira Earthen Dam in Maharashtra,India.In this connection,a series of experimental blasts were conducted by adjusting various blast design parameters at project site.The safe charge weight per delay was kept between 0.125 and 0.375 kg.The outcomes of these experimental blasts were analyzed to recommend optimized blasting patterns and methods for the overall excavation process during actual blasting operations.Blast design parameters,including the maximum quantity of explosive per delay,hole depth,burden and spacing between holes were optimized by using a site-specific attenuation equation,taking into account the proximity of the dam and tunnel from the blasting area.Peak particle velocity(PPV)level of 10 mm/s and 50 mm/s respectively were adopted as the safe vibration level for ensuring safety of the Bhira Earthen Dam and the nearby tunnel from the adverse effects of blast vibrations by analyzing the dominant frequency of ground vibrations observed and also by reviewing various international standards.Frequency of the ground vibrations observed on the dam and tunnel from majority of the blasts was found to be more than 10 Hz and 50 Hz respectively.During the entire period of blasting,the blast vibrations were recorded to be far lower than the safe vibration level set for these structures.Maximum Vibration level of about 0.8 mm/s and 35 mm/s were observed on dam and tunnel respectively which are far lower than the safe vibration level adopted for these structures.Hence,the entire excavation work was completed successfully and safely,without endangering the safety of dam or tunnel.
文摘为研究颗粒阻尼器布置方案对多层结构减震性能的影响,制作了缩尺比为1/5的三层钢框架模型结构,进行了5条天然波下的地震模拟振动台试验,研究并联式单向单颗粒阻尼器(Parallel Single-dimensional Single Particle Damper,PSSPD)的减震控制效果。基于试验获得的模型自振频率、阻尼比等动力特性设计3种PSSPD布置方案,分析不同布置方案下模型结构的试验现象及位移和加速度响应。试验结果表明:PSSPD对结构响应峰值减震率可达到43.43%,均方根减震率可达到38.18%,其对多层结构具有良好的减震控制效果;PSSPD对结构均方根的平均减震效果要优于对峰值的平均减震效果;PSSPD布置方案对其减震效果影响显著,且其减震性能与本身参数、受控结构振动特性、地震动参数之间的耦合关系复杂。最后,建立PSSPD在任意布置方案下受控结构的力学模型,提出其数值分析流程。数值计算结果和试验结果在位移峰值及均方根方面具有良好的吻合度。
文摘传统单颗粒阻尼器存在颗粒半径过大、空间占用率高等局限,多颗粒阻尼器存在启振条件苛刻、动量交换效率低等不足。为提升颗粒阻尼器的减震性能,提出将叠层式单颗粒阻尼器(stacked single particle damper, SSPD),并将其与齿轮齿条惯容装置相结合,进而形成叠层式单颗粒惯容减振系统(stacked single particle-inerter damping system, SSPIS)。在深入分析颗粒各阶段受力状态的基础上,剖析SSPIS减振机理,构建SSPIS-结构系统力学模型,并提出该力学模型的数值模拟流程。为验证SSPIS理论力学模型与数值模拟分析流程的准确性,并探究SSPIS对受控结构的真实减震控制效果,制作钢框架模型结构,完成地震模拟振动台试验。动力试验与理论结果表明:将惯容装置布置于SSPD中可显著提升颗粒与结构的动量交换效率,增大其表观质量与耗能能力,拓宽SSPIS的减振频带。相较于传统颗粒阻尼器,SSPIS在各类场地地震作用下均可对受控结构产生良好的控制效果,具有良好的工程应用前景。
文摘在被动控制装置中,经典调谐质量阻尼器(tuned mass damper,TMD)是应用最为广泛的。然而经典TMD在实际安装使用中往往需要较大的附加质量和较大的安装空间,给实际应用带来不便。旋转惯性双调谐质量阻尼器(rotational inertia double tuned mass damper,RIDTMD)是一种新型的、高效的振动控制装置,它利用了惯容的表观质量增效功能,以及调谐质量和调谐惯容的双重调谐效果,具有较好的减振性能和轻量化控制的特性。然而,当考虑到RIDTMD对基础激励下的主结构控制进行优化设计时,目前的设计方法基本为数值法,不便应用。为解决上述问题,基于H2优化理论,以主结构位移均方根值为目标函数,推导了RIDTMD减震系统的参数解析设计公式。在解析公式的基础上,通过频域和时域两种数值仿真方法分析了RIDTMD的减震性能和轻量化效果,验证了解析公式的准确性和适用性。仿真结果表明:在频域中,RIDTMD对主结构位移频响峰值控制和减震带宽均优于TMD,并具备轻量化和工作行程小的优势;在时域中,以5 MW陆上风机为例,在实际地震波激励作用下,RIDTMD对塔筒一阶纵弯的均方根值和峰值减震均优于TMD,在相同性能指标下能实现较好的轻量化效果。
