【作者】 张俊；

【导师】 陈明；

【作者基本信息】 武汉大学 ， 水工结构工程， 2017， 硕士

【摘要】 近年来,国家大力提倡发展清洁能源,水电作为一种清洁能源已成国民经济发展的绿色动力。水利水电工程建设中,爆破作为岩体开挖、混凝土拆除的主要手段,发挥了重要作用。随着对施工质量和安全性的要求逐步提高,爆破带来的负面效应也越来越引起施工人员的关注。工程中,灌浆帷幕的安全性往往是制约爆破施工的关键因素,为此,国家制定了相应的爆破安全标准,这些标准对灌浆帷幕附近的爆破施工有一定的指导作用,但又显现出保守性,对爆破作业制约较大,影响施工进度。鉴于爆破施工的普遍应用,全面分析爆破振动对灌浆帷幕的影响机理,完善现有灌浆帷幕的爆破振动安全判据的重要性和急迫性逐步凸显。本文以水电站扩机工程为背景,研究爆破振动对水泥灌浆帷幕影响机理,探讨水泥灌浆帷幕的爆破安全判据,论文的主要工作和研究成果如下:(1)研究了岩体灌浆后物理力学性能的变化,岩体中的裂隙被浆液充填固结,其力学特性将得到改善。岩体的变形模量,结构面的抗剪强度、刚度等都和岩体中的声波波速密切相关,根据岩体物理力学参数和声波波速的关系式进行计算,再结合目前的资料,岩体灌浆后,声波波速提高6%～20%,动弹性模量提高9%～16%,结构面粘聚力提高11%～54%,刚度提升最为显著,能达到200%以上。(2)运用波动理论,研究了应力波在介质界面上的透、反射效应,确定了灌浆岩体结构面上的应力状态。引入摩尔-库伦强度准则,计算了岩体灌浆后的允许安全振动速度,结果表明灌浆后临界安全振动速度达到了 12cm/S。计算结果说明灌浆岩体的抗震性能有明显的提升。(3)应用非线性动力有限元软件ANSYS/LS-DYNA,以实际工程为原型,分析灌浆帷幕的爆破振动响应。基岩为软岩时,帷幕振速的峰值最大。各种基岩条件下,坝基段帷幕的振动速度随着深度的增大而减小,但是岸坡内部的帷幕振速不满足此规律。基岩为硬岩时,帷幕的拉应力最大。在天然状态,岸坡内部帷幕顶部已经有一定的拉应力,爆破振动传播到该处后,动拉应力会在此基础上进一步增大;坝基段帷幕未受扰动时处于受压的状态,对动拉应力的产生有一定的抑制作用,相对来说要安全些。帷幕振动速度超过1Ocm/s时,最大拉应力仍低于帷幕的抗拉强度。对于岸坡内部的帷幕,可以选择灌浆廊道的底板来控制整个帷幕的振动速度,但对于坝基段的帷幕,廊道底板的振速小于帷幕的振速。(4)基于上述研究,分别提出基于理论分析的灌浆帷幕的爆破振动安全判据和基于理数值模拟的安全判据,结合工程实践中使用的安全判据,再综合考虑灌浆帷幕的安全性和施工进度,提出建议的帷幕允许振动速度。帷幕灌注质量较高时,坝基段廊道的振动速度不宜超过5cm/s,岸坡内部灌浆平洞的振动速度不宜超过8cm/s。论文研究成果对认识灌浆帷幕受爆破振动影响机理具有重要的意义,对减少和防止因工程作用引起的损失具有应用价值。更多还原

【Abstract】 In recent years,China has highly promoted the development of clean energy,as a kind of clean energy,hydropower has become a green force for national economic development.And a large number of hydropower station expanding units projects are going on or about to be carried out.As a main mean of blasting excavation and concrete demolition,blasting is widely used in these expanding units projects.With the requirement of quality and safety of the construction,negative effects caused by blasting have been paid more and more attention.In hydropower engineering,safety of grouting curtain is always a key factor which restricts the blasting operation,therefore,the corresponding safety standards for blasting have been carried out,these standards have instructive effect on blasting operation near the grouting curtain.However,in practice,these standards have shown conservatism and hampered the construction schedule.As blasting operation in expanding units projects is widely used,a deep analysis of the safety influence of blasting vibration on grouting curtain is required,so is the improvement of existing blasting vibration safety criterion of grouting curtain.Based on Gezhouba Lock Reconstruction Project and Wuqiangxi Hydropower Station Expanding Units Project,characteristics,harmful effects and damage standards of blasting vibration are summarized.Through theoretical calculation and numerical simulation,the interaction of the stress wave and the structural plane in the grouting curtain is studied,the influence mechanism of blasting vibration on cement grouting curtain is discussed and some suggestions are proposed to improve the blasting vibration safety criterion of the grouting curtain.Specific research work and results are as follows:(1)Formation,composition and propagation law of blasting seismic wave are summarized.Threatens of blasting vibration to hydraulic structures are discussed.The present standards for blasting vibration in hydraulic and hydropower engineering are discussed.(2)Grouting quality is directly related to the properties of cement slurry and the grouting technology.Seepage control mechanism of the grouting curtain is explained from the angle of cement grouting construction.Based on the existing test and engineering data,the mechanical and deformation characteristics of grouting rock mass are summarized.Interaction between stress wave and structural plane is analyzed,the allowable vibration velocity is determined,and the failure mechanism of cement stone-rock interface is also discussed.In general,compared with the natural structure,strength of the cement stone-rock interface,especially the shear strength,is greatly improved,therefore the ability of grouting rock mass to resist the influence of blasting vibration enhances significantly.(3)Nonlinear dynamic finite element software ANSYS/LS-DYNA is used to analyze the blasting vibration response of grouting curtain.Attenuation law of blasting vibration velocity is studied,and vibration characteristics of grouting curtain at different depths are compared.In General,with the increase of depth,the vibration velocity of the curtain decreases.Dam heel and the grouting gallery can be chosen as the blasting safety control points respectively for dam foundation curtain and bank slope curtain.(4)Based on the above research,safety criterions of grouting curtain are put forward respectively based on the theoretical analysis and numerical simulation.Combined with the safety criterion used in engineering practice,meanwhile considering the safety and construction progress of the grouting curtain,improved safety criterion of vibration is recommended.For well grouted curtain,the allowable vibration velocity at grouting gallery should not exceed 5cm/s,and for grouting adit,it is 8cm/s.更多还原