密集型塔基桩孔开挖控制爆破技术
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摘要
针对泸定大渡河特大桥塔基桩孔布置密集的状况和开挖区基岩节理裂隙发育的特点,应用短进尺、锥形掏槽的减震光面爆破技术进行直径2.8 m圆形桩孔的全断面掘进。尤其是在桩孔间净距仅为3.2 m时,采用锥形掏槽逐孔毫秒延迟起爆技术,并通过在掏槽中心空孔内布设0.1~0.2 kg的抛渣药包后于掏槽孔起爆,达到提高爆破效果、减弱爆破振动目的。在详细给出桩孔开挖控制爆破技术措施、爆破参数和施工方法的基础上,利用现场实测数据进行爆破效果、振动效应和围岩稳定等分析。工程实践表明:锥形掏槽逐孔毫秒延迟起爆技术能使邻近桩孔围岩的爆破振动强度得到有效控制,开挖爆破在邻近桩孔内产生的最大峰值振动速度小于10 cm/s,满足围岩安全振动控制标准;爆破前后桩孔围岩波速的平均下降率3.74%,远小于技术规范规定的10%的声波下降率量化标准;桩孔单循环爆破进尺约1.2~1.3 m,开挖壁面平整,基本没有超欠挖,保持了围岩的完整性和稳定性。
Owing to the extra-large bridge of Luding Dadu river with the condition of intensive pile holes in tower footing and joint fissures,the short footage and damping smooth blasting technology with conical cut were taken into the whole section excavating with diameter 2. 8 m pile hole. Especially,when the clear distance between pile holes was only 3. 2 m,the millisecond delaying detonation technology of conical cut hole-by-hole was designed. By charging0. 1 to 0. 2 kilogram explosive into empty holes bottom which detonated behind cutting holes,the good blasting effect and reduced blasting vibration were obtained. When the detail information of the technical measures of controlled blasting,the blasting parameters and construction methods on the excavation of pile holes were given,the field test data was used to analyze the blasting effect,the vibration effect and stability of surrounding rock. The engineering practice shows that the blasting vibration of the adjacent pile hole could be better controlled by the millisecond delaying detonation technology of conical cut hole-by-hole,and the peak vibration velocity in the adjacent pile hole caused by excavation blasting could be controlled less than 10 cm / s,which met the control standard of safety vibration of surrounding rocks well. The P-wave velocity of surrounding rock of the pile hole decreased by the average rate of 3. 74%,far less than 10% sound waves reduction rate of quantitative criteria. By designing the single blasting footage of pile hole with 1. 2 ~ 1. 3 m,the excavation surface and over and back break were controlled well,finally the integrity and stability of the surrounding rock was kept well.
Owing to the extra-large bridge of Luding Dadu river with the condition of intensive pile holes in tower footing and joint fissures,the short footage and damping smooth blasting technology with conical cut were taken into the whole section excavating with diameter 2. 8 m pile hole. Especially,when the clear distance between pile holes was only 3. 2 m,the millisecond delaying detonation technology of conical cut hole-by-hole was designed. By charging0. 1 to 0. 2 kilogram explosive into empty holes bottom which detonated behind cutting holes,the good blasting effect and reduced blasting vibration were obtained. When the detail information of the technical measures of controlled blasting,the blasting parameters and construction methods on the excavation of pile holes were given,the field test data was used to analyze the blasting effect,the vibration effect and stability of surrounding rock. The engineering practice shows that the blasting vibration of the adjacent pile hole could be better controlled by the millisecond delaying detonation technology of conical cut hole-by-hole,and the peak vibration velocity in the adjacent pile hole caused by excavation blasting could be controlled less than 10 cm / s,which met the control standard of safety vibration of surrounding rocks well. The P-wave velocity of surrounding rock of the pile hole decreased by the average rate of 3. 74%,far less than 10% sound waves reduction rate of quantitative criteria. By designing the single blasting footage of pile hole with 1. 2 ~ 1. 3 m,the excavation surface and over and back break were controlled well,finally the integrity and stability of the surrounding rock was kept well.
引文
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[2]梁开水,王玉杰,唐楷,等.基础桩井岩石开挖爆破[J].爆破,1997,14(3):48-51.LIANG Kai-shui,WANG Yu-jie,TANG Kai,et al.Excavation blasting of rock in foundation pile-well[J].Blasting,1997,14(3):48-51.(in Chinese)
[3]王为.立交桥桥脚桩基岩石开挖爆破[J].爆破,2000,17(2):67-68.WANG Wei.Explosive demolition of the footing of overpass bridge pier[J].Blasting,2000,17(2):67-68.(in Chinese)
[4]张继春,吴青山,夏真荣,等.抗拔桩孔开挖控制爆破技术[J].爆破,2001,18(2):26-29.ZHANG Ji-chun,WU Qing-shan,XIA Zhen-rong,et al.Controlled blasting technique of the excavation of tensile pile holes[J].Blasting,2001,18(2):26-29.(in Chinese)
[5]唐润婷,李鹏飞,苏华友.桥梁桩基爆破施工对邻近埋地天然气管线的影响[J].工程爆破,2011,17(1):78-81.TANG Run-ting,LI Peng-fei,SU Hua-you.Influence of blasting construction of the bridge pile foundation on adjacent buried gas pipeline[J].Engineering Blasting,2011,17(1):78-81.(in Chinese)
[6]苏军.临近既有线深孔桩基爆破施工技术[J].铁道建筑技术,2014(5):114-116.SU Jun.Construction technology of deep hole pile foundation blasting near existing line[J].Railway Construction Technology,2014(5):114-116.(in Chinese)
[7]程远学,程康,周子然,等.人工挖孔桩爆破开挖技术探讨[J].土工基础,2007,21(4):5-6.CHENG Yuan-xue,CHENG Kang,ZHOU Zi-ran,et al.Discussion of explosive excavation technique of hand-dug pile[J].Soil Engineering and Foundation,2007,21(4):5-6.(in Chinese)
[8]郗庆桃.隧道爆破震动控制技术[J].爆破,1998,15(4):83-87.XI Qing-tao.Control Measures for explosive vibration in tunnel[J].Blasting,1998,15(4):83-87.(in Chinses)
[9]张世雄,胡建华,阳生权,等.地下工程爆破振动监测与分析[J].爆破,2001,18(2):49-52.ZHANG Shi-xiong,HU Jian-hua,YANG Sheng-quan,et al.Monitoring and analysis of blast vibration in underground engineering[J].Blasting,2001,18(2):49-52.(in Chinese)
[10]张继春,曹孝君,郑爽英,等.浅埋隧道掘进爆破的地表震动效应试验研究[J].岩石力学与工程学报,2005,24(22):4158-4163.ZHANG Ji-chun,CAO Xiao-jun,ZHENG Shuang-ying,et al.Experimental study on vibration effects of ground due to shallow tunnel blasting[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(22):4158-4163.(in Chinese)
[11]楼晓明,郑俊杰,马建军,等.隧道爆破振动速度研究[J].有色金属(矿山部分),2007,59(3):31-34.LOU Xiao-ming,ZHENG Jun-jie,MA Jian-jun,et al.Study on blasting vibration velocity in tunnel[J].Nonferrous Metal(Mine),2007,59(3):31-34.(in Chinese)