水电站岸坡强卸荷岩体防渗灌浆试验研究
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摘要
岩体中的裂隙是地质作用形成的不连续面,它控制着岩体的强度和渗流特征。灌浆是处理此类地质问题的有效手段之一。灌浆是采用水泥浆液在压力的作用下使浆液在岩体中一定范围内扩散,充填岩体中的裂隙,封闭渗流通道,形成连续的、有一定厚度的幕体,达到防渗堵漏的目的。
羊曲水电站位于青海省海南州兴海与贵南交界处的黄河干流上,下游与龙羊峡水库尾衔接,是茨哈至班多、羊曲河段梯级规划的最下一个梯级电站。水库正常蓄水位2715m,水库总库容23.05亿m3。总装机容量1200MW,装4台300MW水轮发电机组,多年平均年发电量49.1亿kW·h。工程规模为一等大(1)型,推荐的下坝址枢纽主要由拦河大坝、泄洪建筑物和引水发电建筑物组成。
羊曲水电站下坝址两岸坝肩强卸荷带的卸荷裂隙,宽度一般为10-30cm,最大可达到50cm。如果采用常规的帷幕灌浆方法,浆液会随裂隙的延伸扩散较远,吃浆量大,扩散范围难以控制,且灌浆压力达不到设计要求,结石强度不高,灌浆最终难以达到防渗堵漏的效果。
本次灌浆试验的目的,是在了解试验区地质条件的基础上,制定的灌浆工艺和参数,通过现场灌浆试验和对灌后检查资料的分析,论证岩体的可灌性和帷幕的可靠性,总结并完善了灌浆方法、灌浆方法和灌浆参数。灌浆方法采用自上而下、孔口封闭、孔内循环的方式,灌浆孔采用四排孔的平面布置形式。其中第一排、第四排孔为试验区两侧的封闭灌浆孔,主要是封闭试验区两侧的宽大裂隙,形成一个相对封闭的区域,起到控制浆液扩散范围的作用。为第二排和第三排孔为帷幕灌浆主体孔。试验孔单排采用直线式布置,排距60cm,孔间距1.0m,孔序分为三序,采用水泥浆灌注,最大灌浆压力为4.0MPa。在较大注入量情况下,采用投入细砂、浓浆灌注和掺加水玻璃、结合间歇灌浆的综合灌浆法。
灌浆后采用五点法压水试验、检查孔取芯、物探纵波测试、钻孔全孔壁数字成像技术等手段检测灌浆效果。结果表明,实施灌浆后,岩体的吕荣值显著减小。灌前钻孔不返水,压水试验无法起压,透水率趋于无穷大的部位,灌后均小于1.OLu。物探检测表明岩体纵波波速灌后为3000-5000m/s。灌浆后岩芯采取率大于95%,帷幕防渗效果满足规范要求。钻孔全孔壁数字成像成果表明,水泥浆液在岩体内沿裂隙运动,灌浆后裂隙充填率高,结石体强度较高,总体灌浆效果良好。
Rock fissure as one kind of geological discontinuities is a main factor controlling the rock mass strength and flow characteristics. Cement grouting under pressure is used to fill the rock fissures, forming a certain thickness of continuous rock body to achieve the purpose of plugging seepage.
Yangqu hydraulic power station on the Yellow River is located at the junction place of Xinghai and Guinan of Qinghai province. The downstream water runs into the with Longyangxia reservoir. The station is the last station planed between the Ciha and Banduo of Yangqu river, with a normal water level of 2715m, and a total reservoir storage capacity of 2.305 billion m3. The total generation capacity is 1200MW (300MW by 4 generating units) and the multi-year average power output reaches 4.91 billion kw·h. The power station is a first-class project, composed mainly by dam, flood discharge structures and electric generating structures.
Rock slope at the dam site of Yangqu station is characterized by unloaded fractures with width of 10-30cm, and a maximum of 50cm. If using the conventional method of curtain grouting, cement slurry might spread farther along fractures, resulting in large quantity of cement leakage because of the difficulty for spread control. Therefore, grouting pressure can not meet the design requirements, and ground water seepage can not be cut off effectively.
By studying the geological conditions of experimental area, this test try to investigate the grouting process through one-site inspection after grouting test, so to evaluate the curtain reliability, improve the grouting process and parameters. Grouting test is conducted from the top to the bottom within closed bore holes. The grouting holes are designed in four rows, of which the first row and the fourth row of holes on both sides of the test area are used to form a relatively closed area for controlling the spread of slurry during the next grouting. The second and third rows of the holes are used to create major curtain. The distance between two rows is 60cm, and the space between two hole within the same row is 1.0m. Grouting is done in three sequences wit a maximum pressure of 4.0MPa. In case that a larger amount of cemen injection occurred, grouting is improved by a series methods such a thick paste, addition of water glass, or by intermittent and comprehensive grouting.
After grouting, detection is conducted by means of a five-point water pressure test, inspection of hole core, geophysical P-wave test, drill hole digital imaging technology. Test results showed that the lugeon value of the rock after grouting is significantly reduced. For the holes that was characterized previously before grouting by no return of drilling water or by zero water pressure during grouting, the water permeability tends to infinity, and the lugeon value become less than 1.0 after grouting. Geophysical exploration showed that the longitudinal wave speed increase to 3000-5000m/s after grouting, and the core rate recovery increase more than 95%. Drill hole digital imaging results showed that the cemented stone fills the fissures in a good condition. As final conclusion, grouting designed get a reliable achievement.
羊曲水电站位于青海省海南州兴海与贵南交界处的黄河干流上,下游与龙羊峡水库尾衔接,是茨哈至班多、羊曲河段梯级规划的最下一个梯级电站。水库正常蓄水位2715m,水库总库容23.05亿m3。总装机容量1200MW,装4台300MW水轮发电机组,多年平均年发电量49.1亿kW·h。工程规模为一等大(1)型,推荐的下坝址枢纽主要由拦河大坝、泄洪建筑物和引水发电建筑物组成。
羊曲水电站下坝址两岸坝肩强卸荷带的卸荷裂隙,宽度一般为10-30cm,最大可达到50cm。如果采用常规的帷幕灌浆方法,浆液会随裂隙的延伸扩散较远,吃浆量大,扩散范围难以控制,且灌浆压力达不到设计要求,结石强度不高,灌浆最终难以达到防渗堵漏的效果。
本次灌浆试验的目的,是在了解试验区地质条件的基础上,制定的灌浆工艺和参数,通过现场灌浆试验和对灌后检查资料的分析,论证岩体的可灌性和帷幕的可靠性,总结并完善了灌浆方法、灌浆方法和灌浆参数。灌浆方法采用自上而下、孔口封闭、孔内循环的方式,灌浆孔采用四排孔的平面布置形式。其中第一排、第四排孔为试验区两侧的封闭灌浆孔,主要是封闭试验区两侧的宽大裂隙,形成一个相对封闭的区域,起到控制浆液扩散范围的作用。为第二排和第三排孔为帷幕灌浆主体孔。试验孔单排采用直线式布置,排距60cm,孔间距1.0m,孔序分为三序,采用水泥浆灌注,最大灌浆压力为4.0MPa。在较大注入量情况下,采用投入细砂、浓浆灌注和掺加水玻璃、结合间歇灌浆的综合灌浆法。
灌浆后采用五点法压水试验、检查孔取芯、物探纵波测试、钻孔全孔壁数字成像技术等手段检测灌浆效果。结果表明,实施灌浆后,岩体的吕荣值显著减小。灌前钻孔不返水,压水试验无法起压,透水率趋于无穷大的部位,灌后均小于1.OLu。物探检测表明岩体纵波波速灌后为3000-5000m/s。灌浆后岩芯采取率大于95%,帷幕防渗效果满足规范要求。钻孔全孔壁数字成像成果表明,水泥浆液在岩体内沿裂隙运动,灌浆后裂隙充填率高,结石体强度较高,总体灌浆效果良好。
Rock fissure as one kind of geological discontinuities is a main factor controlling the rock mass strength and flow characteristics. Cement grouting under pressure is used to fill the rock fissures, forming a certain thickness of continuous rock body to achieve the purpose of plugging seepage.
Yangqu hydraulic power station on the Yellow River is located at the junction place of Xinghai and Guinan of Qinghai province. The downstream water runs into the with Longyangxia reservoir. The station is the last station planed between the Ciha and Banduo of Yangqu river, with a normal water level of 2715m, and a total reservoir storage capacity of 2.305 billion m3. The total generation capacity is 1200MW (300MW by 4 generating units) and the multi-year average power output reaches 4.91 billion kw·h. The power station is a first-class project, composed mainly by dam, flood discharge structures and electric generating structures.
Rock slope at the dam site of Yangqu station is characterized by unloaded fractures with width of 10-30cm, and a maximum of 50cm. If using the conventional method of curtain grouting, cement slurry might spread farther along fractures, resulting in large quantity of cement leakage because of the difficulty for spread control. Therefore, grouting pressure can not meet the design requirements, and ground water seepage can not be cut off effectively.
By studying the geological conditions of experimental area, this test try to investigate the grouting process through one-site inspection after grouting test, so to evaluate the curtain reliability, improve the grouting process and parameters. Grouting test is conducted from the top to the bottom within closed bore holes. The grouting holes are designed in four rows, of which the first row and the fourth row of holes on both sides of the test area are used to form a relatively closed area for controlling the spread of slurry during the next grouting. The second and third rows of the holes are used to create major curtain. The distance between two rows is 60cm, and the space between two hole within the same row is 1.0m. Grouting is done in three sequences wit a maximum pressure of 4.0MPa. In case that a larger amount of cemen injection occurred, grouting is improved by a series methods such a thick paste, addition of water glass, or by intermittent and comprehensive grouting.
After grouting, detection is conducted by means of a five-point water pressure test, inspection of hole core, geophysical P-wave test, drill hole digital imaging technology. Test results showed that the lugeon value of the rock after grouting is significantly reduced. For the holes that was characterized previously before grouting by no return of drilling water or by zero water pressure during grouting, the water permeability tends to infinity, and the lugeon value become less than 1.0 after grouting. Geophysical exploration showed that the longitudinal wave speed increase to 3000-5000m/s after grouting, and the core rate recovery increase more than 95%. Drill hole digital imaging results showed that the cemented stone fills the fissures in a good condition. As final conclusion, grouting designed get a reliable achievement.
引文
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[2]陆佑楣.中国水电开发与可持续发展[J].水利水电技术,2005,36(2)：1-4.
[3]肖蔻.中国水利水电开发中世界级工程及其顶尖技术[J].中国三峡建设(科技版),2008(1)：82-84.
[4]胡刚.我国水电开发现状及筹资构想[J].水力发电,1996(7)：34-37.
[5]贺恭.中国水电未来之路：加快开发与可持续发展[J].水利水电技术,2005,36(2)：5-8.
[6]王昆.眉山市水利水电工程主要环境地质问题及防治对策[J].四川水利,2008(4)：57-60.
[7]曾国熙,卢肇钧,蒋国澄,等.地基处理手册[M].北京：中国建筑工业出版社,1988.
[8]何修仁等.注浆加固与堵水[M].沈阳：东北土学院出版社,1990.
[9]彭振斌,胡焕,许宏武,等.注浆工程设计计算与施工[M].武汉：中国地质大学出版社,1997.
[10]煤炭科研参考资料组.国外注浆技术概况[M].北京：科学出版社,1972.
[11]大坝化学灌浆技术经验汇编小组.大坝化学灌浆技术经验汇编[M].北京：水利电力出版社,1977.
[12]葛家良.注浆技术的现状与发展趋向综述[A].首届全国岩石锚固与灌浆技术学术讨论会[C].北京,1995.
[13]Yonekura R.. Recent chemical grouting engineering for underground construction[A]. Proc. of the International Symposium on Anchoring and Grouting Techniques[C]. Dec.,Guangzhou,1994,97-113.
[14]白俊平.GIN法灌浆技术试验研究[D].太原理工大学硕士学位论文,2003.
[15]孙钊.大坝岩石基础灌浆施工[M].北京：水利电力出版社,1987.
[16]梁仁友,邢开第.国内外工程灌浆的发展概况[J].勘察科学技术,1987(1)：12-15.
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