Rock mechanical problems and optimization for the long and deep diversion tunnels at Jinping Ⅱ hydropower station

According to site-specific environments such as high water pressures, high in-situ stresses and strong rockbursts, the design scheme of the long and deep diversion tunnels at Jinping II hydropower station was optimized to ensure construction safety. New drainage tunnels were considered. Furthermore, lining structures and grouting pressures were modified during the excavation of tunnels. The construction scheme was updated dynamically based on the complex geological conditions. For instances, the diversion tunnels were first excavated by drilling and blasting method at the first stage of construction, and then by the combination method of tunnel boring machine （TBM） and drilling and blasting, and finally by drilling and blasting method. Through optimized scheme and updated construction scheme, the excavation of diversion tunnel #1 was successfully completed in June, 2011. This paper summarizes the key issues in rock mechanics associated with the construction of the long and deep diversion tunnels at Jinping II hydropower station. The experiences of design and construction obtained from this project could provide reference to similar projects.

Tempo-spatial characteristics and influential factors of rockburst:a case study of transportation and drainage tunnels in Jinping Ⅱ hydropower station

Jinping Ⅱ hydropower station is located in a high in-situ stress region in Southwest China. During the excavations of the transportation and drainage tunnels, more than 460 rockburst events were recorded in the transportation tunnel and 110 in the drainage tunnel, which has a serious and negative influence on the tunnels’ construction and the safety of staff and equipment. In the paper, the characters of rockburst patterns are analyzed for the transportation and drainage tunnels. The results are illustrated as follow: (1) Most of intensive rockbursts occur in the layer T2b, and continuous occurrences of rockbursts are more frequently observed than those in other layers. (2) The critical overburden depth of rockburst in the transportation tunnel is 600 m, and the length of the continuous occurrence section of rockburst is smaller than 25 m. The damaged depth of the rockburst has the tendency to increase with the increasing overburden depth, and the maximum damaged depth is over 3.5 m. (3) From east to west (west to east) in Jinping Ⅱ hydropower station, the rockburst usually takes place in the right (left) side of tunnel working face, and then the left (right) or roof of the tunnel. The total length of the continuous occurrence section of rockburst is 57.4%–62.2% of the overall rockburst length, followed by the rockbursts of flake-splitting type and other types. (4) Compared with the transportation tunnel, the intensity of rockburst in the drainage tunnel is higher while the length of the continuous occurrence section of rockburst is smaller. The rockburst section with length less than 10 m and depth of 1 m mainly occurs in the layer at a depth of 1 800–2 000 m. The influences of opening geometry and excavation method on the characteristics of the adjacent zone are great, but the influence of the stress among the tunnel group induced by excavation is relatively low.

Measures for controlling large deformations of underground caverns under high in-situ stress condition--A case study of JinpingⅠhydropower station

The Jinping I hydropower station is a huge water conservancy project consisting of the highest concrete arch dam to date in the world and a highly complex and large underground powerhouse cavern. It is located on the right bank with extremely high in-situ stress and a few discontinuities observed in surrounding rock masses. The problems of rock mass deformation and failure result in considerable challenges related to project design and construction and have raised a wide range of concerns in the fields of rock mechanics and engineering. During the excavation of underground caverns, high in-situ stress and relatively low rock mass strength in combination with large excavation dimensions lead to large deformation of the surrounding rock mass and support. Existing experiences in excavation and support cannot deal with the large deformation of rock mass effectively, and further studies are needed. In this paper, the geological conditions, layout of caverns, and design of excavation and support are first introduced, and then detailed analyses of deformation and failure characteristics of rocks are presented. Based on this, the mechanisms of deformation and failure are discussed, and the support adjustments for controlling rock large deformation and subsequent excavation procedures are proposed. Finally, the effectiveness of support and excavation adjustments to maintain the stability of the rock mass is verified. The measures for controlling the large deformation of surrounding rocks enrich the practical experiences related to the design and construction of large underground openings, and the construction of caverns in the Jinping I hydropower station provides a good case study of large-scale excavation in highly stressed ground with complex geological structures, as well as a reference case for research on rock mechanics.

Treatment design of geological defects in dam foundation of Jinping I hydropower station

Jinping I hydropower station is one of the most challenging projects in China due to its highest arch dam and complex geological conditions for construction.After geological investigation into the dam foundation,a few large-scale weak discontinuities are observed.The rock masses in the left dam foundation are intensively unloaded,approximately to the depth of 150–300 m.These serious geological defects lead to a geological asymmetry on the left and right banks,and thus some major diffculties of dam construction are encountered.In this paper,the influences of geological defects on the project are analyzed,followed by the concepts and methods of treatment design.Based on the analysis,the treatment methods of the weak rock masses and discontinuities are carefully determined,including the concrete cushion,concrete replacement grids,and consolidation grouting.They work together to enhance the strength and integrity of the dam foundation.Evaluations and calibrations through geo-mechanical model tests in combination with feld monitoring results in early impoundment period show that the arch dam and its foundation are roughly stable,suggesting that the treatment designs are reasonable and effective.The proposed treatment methods and concepts in the context can be helpful for similar complex rock projects.

2002—2021年雅砻江锦屏一级水电站库区NDVI时空变化及其与气候因子的相关性

利用长时间序列的MODIS遥感影像和气象数据,应用归一化植被覆盖度指数(NDVI)、趋势分析、Mann-Kendall统计检验法、相关分析等方法,分析了2002—2021年雅砻江锦屏一级水电站库区植被覆盖的时空分布和变化趋势,对植被覆盖度的变化突变点进行识别,探讨了区域植被覆盖度与气候的关系,解释了可能导致植被覆盖度变化的原因。结果表明:1)近20年来,锦屏一级水电站库区NDVI总体呈增长趋势,海拔3000~3500 m是区域内NDVI最高的区间,NDVI呈现减少主要为近库区沿岸海拔2500 m以下区域,呈现增加的主要集中在库区西南部、西北部及东北部海拔2500~3500 m区域;2)锦屏一级水电站库区蓄水前10年植被覆盖度增加速度低于蓄水后10年的植被覆盖度增加速度,并在蓄水完成的2014年出现了转折点;3)锦屏一级水电站库区植被覆盖度的变化与湿度、降水相关,区域内生态保护与恢复工程和库区防护林营造工程的实施也起到了一定成效。

Safety monitoring and stability analysis of left abutment slope of Jinping Ⅰ hydropower station

Safety monitoring and stability analysis of high slopes are important for high dam construction in high mountainous regions or precipitous gorges. In this paper, deformation characteristics of toppling block at upper abutment, deforming tensile rip wedge in the middle part and deep fractures are comprehensively analyzed based on the geological conditions, construction methods and monitoring results of left abutment slope in Jinping Ⅰ hydropower station. Safety analyses of surface and shallow-buried rock masses and the corresponding anchorage system are presented. The monitoring results indicate that the global stability of the large wedge block in the left abutment is effectively under control, and the abutment slope is stable in a global sense. After the completion of excavation, the deformations of toppling block at the top of the slope and deep fracture zone continue at a very low rate, which can be explained as 'rock mass creep'. Further monitoring and analysis are needed.

水轮发电机组GD^(2)估算分析与统计公式拟合研究

水轮发电机组转动惯量是衡量水电机组快速反应性能的关键指标,对于机组的稳定和电力系统的稳定均具有极其重要的影响。在工程中常采用飞轮力矩GD^(2)来表征水轮发电机组转动惯量的大小,在水电站预可研、可研设计阶段,水轮发电机组GD^(2)的取值多采用估算的方式来确定。本文通过典型工程实例和大量的统计数据对目前常用的两类GD^(2)估算公式进行分析,提出合理化的选取建议。并采用近年国内已投产水电站机组GD^(2)真实样本拟合构建的新公式。可为电站初期设计阶段的机组GD^(2)合理估算提供更精确的计算依据。

锦屏一级水电站库区中小地震震源机制解与局部应力场特征

利用四川及邻区数字地震台网2013—2018年的波形资料,基于CAP和HASH方法反演得到锦屏一级水电站(以下简称锦屏水库)库区及周边M_(L)≥2.5地震的震源机制解,根据DRSSI方法计算得到库区局部应力场信息,结合该区域的地质资料,从震源机制参数和局部应力场变化等方面讨论了水库加卸载对该区域地震活动的影响.取得的主要认识如下:(1)库区地震活动类型以走滑型为主,不同加卸载阶段震源机制类型存在一定差异,库区蓄水前期震源机制类型呈现多样性,蓄水后期与区域背景场趋于一致;(2)库区应力场最大主应力方向以NNW-SSE向为主,分时段结果显示,蓄水后期局部应力场最大主应力方向由NNW向逐渐发生偏转至NW向;(3)库区周边的地质构造和岩性条件有利于库水的渗透,蓄水后重力载荷和流体渗透的共同作用导致岩体断层面库仑应力的变化,从而呈现出库区蓄水前后中小地震活跃程度的显著差异特征.

平行F42-9发育的结构面对锦屏水电站高边坡稳定性的影响

锦屏一级水电站左岸高边坡F42-9断层及煌斑岩脉组合的滑块对左岸缆机平台及拱肩槽边坡的稳定性起到控制性的作用。针对F42-9断层两侧平行结构面的发育程度,进行了锚固边坡开挖过程中的弹塑性力学行为分析。结果表明:平行于F42-9断层发育的结构面使锚固边坡岩体的性状急剧下降,现有的加固方案无法满足边坡稳定性的要求。建议根据边坡及抗剪洞开挖过程中揭露的地质信息,及时制定合理的边坡加强、加固措施。

基于NB35047-2015规范的锦屏拱坝抗震复核

能源行业标准《水电工程水工建筑物抗震设计规范》(NB35047-2015)已于2015年9月1日颁布实施。介绍了依据该规范开展的锦屏一级高拱坝抗震安全复核工作。主要内容包括:基于设定地震的场地相关设计反应谱研究;采用动力拱梁分载法、线弹性有限元法和非线性有限元法,进行设计和最大可信地震作用下的应力和坝肩岩体动力稳定分析;在选定的人工地震波基础上,采用以基岩峰值加速度在设计地震基础上比例放大的方式,进行大坝地基系统在超设计地震荷载下的地震超载能力分析。复核分析表明,锦屏一级高拱坝具有较高的抗震潜力;设计地震和最大可信地震作用下,坝体抗压强度安全满足现行抗震规范要求,且抗压强度安全有较大安全裕度,坝体拉应力基本未超过混凝土容许的应力范围,仅局部应力集中部位拉应力较大,能满足校核地震作用下"不溃坝"的设防要求。

锦屏电站引水隧洞φ12.43m大直径TBM组装洞室设计与施工

据地质条件和TBM的形式、安装方式及采用的吊装设备,以及刀盘直径、TBM组件尺寸等因素,在充分考虑扩大洞室的功能特性、施工方法、衬砌结构等的组装、始发需要,并考虑TBM主机大件的摆放、部件转运所需的卸车区域等设计洞室的断面、长度、支护形式、衬砌结构、桥吊运行基础等,就施工过程提出有力的措施,以保证施工质量、安全与速度。上述设计方案与施工措施,为确保大直径TBM洞内顺利组装奠定了基础。

基于老挝南立1-2水电站的境外投资项目浅析

以老挝南立1-2水电站为基础,分析老挝南立1-2水电站项目在立项和可靠性研究、协议谈判和国内政府审批、融资、项目建设和运营等阶段的特点,提出在境外投资项目过程中应做好风险预测和风险分摊工作,充分利用国内外有利政策,与政府及合作单位建立良好关系,以及注重品牌建设等措施,为境外投资项目的规划、融资、建设、运营提供了一定的借鉴和参考。

水口水电站2×500t级垂直升船机

水口水电站２×５００ｔ级垂直升船机为目前国内首座在建的大型全平衡式湿运垂直升船机，其设计、施工、制造及安装调试均属国内首次。目前其各项前期工作已全部结束，土建施工、机械设备及金属结构制造正在按计划进行，国际采购的关键设备年内将陆续到货。根据整个工程进度计划：１９９６年土建工程、机械设备及金属结构、电气设备制造完成，１９９７年金属结构及机电设备安装以及单项调试完成，１９９８年上半年整机联调完成并正式投入运行。垂直升船机作为解决高坝通航的一种有效途径，且有运行周期短、工程量少、节约能源、不耗水、建筑物结构紧凑易于布置等优点。但长期以来，由于种种原因，国内大型升船机领域始终停留在实验、理论的阶段，因此水口升船机的建设将是这一领域的一个突破，通过水口升船机的建设我们期望能够摸索出一条适合我国国情的建设大型升船机的道路，同时也为建设更大规模的升船机，特别是三峡升船机积累有益的经验。

HK-G-2环氧灌浆材料在钢衬脱空处理中的应用

钢衬在水电站压力管道中应用十分普遍。混凝土浇筑完毕后,钢衬与混凝土接触面或多或少会出现脱空。为保证钢衬整体结构的稳定性,通常都对脱空进行接触灌浆,一般以水泥灌浆为主,化学灌浆则用于水泥灌浆后的辅助补强。化学灌浆材料通常选用环氧材料。本文主要介绍HK-G-2环氧灌浆材料的性能及在景洪水电站、张河湾水电站等压力钢管钢衬脱空补强中的应用。

锦屏一级大坝左岸建基面f2断层处理施工技术

锦屏一级大坝建基面地质条件复杂,断层及层间挤压错动带发育,其中规模较大、延伸较长的地质缺陷主要有f2,f5,f8等断层及煌斑岩脉,需采取刻槽置换、高压水冲洗、固结灌浆等工程措施进行处理,以满足拱坝基础承载力与抗渗稳定性要求。以锦屏一级大坝左岸建基面f2断层及层间挤压带地质缺陷处理为例,介绍了地质缺陷处理的原则和几种关键施工技术,可为类似工程坝基地质缺陷处理提供借鉴。

老挝塞坎曼2水电站开发方案研究

针对老挝塞坎曼2(Xe Kaman 2)水电站开发项目受上、下游已建、在建水电站的影响,选址空间有限,且河道比降较小,局限了开发方案的选择等问题,通过多次勘查、测量、分析研究,从技术、经济、环境等方面综合比较了两种可能的坝址和厂房位置,最终确定了该电站的开发方案,奠定了项目开发的基础。

装配式预应力混凝土桥梁在老挝南椰2水电站的应用

老挝南椰2水电站厂房交通桥的梁采用后张法装配式预应力混凝土T形梁取得了成功,其优点为:保障安全、保证质量、施工速度快、工程造价低。本文重点对装配式预应力T形梁结构及施工过程作一介绍,为类似桥梁设计施工提供借鉴。

锦屏一级水电站坝基f2断层水泥灌浆施工技术

断层及层间挤压错动带采用高压水冲洗置换灌浆的方式进行处理,能够冲洗出一部分软弱介质,冲洗后的空腔再采用水泥浆液进行置换固结灌浆,相当于在断层上施加了水泥柱桩,提高了断层基础的承载力。本文介绍锦屏一级水电站大坝左岸f2断层高压冲洗水泥置换灌浆加固施工技术的成功运用。

老挝南坎2水电站砂石加工系统的设计与研究

介绍了老挝南坎2水电站砂石加工系统的设计过程,包括生产规模、设备选型以及工艺流程设计的具体情况。通过对关键生产工艺进行研究,采用了合理的破碎、制砂、筛分和砂处理等生产工艺,并对生产过程中影响产品质量的环节采取了相应的改善措施,使所生产出的成品砂石料产品的质量满足工程质量技术要求。

越南昆江2水电站金属结构布置与设计

文章介绍越南昆江2水电站金属结构布置和设计成果。拦污栅与启闭机、检修闸门与启闭机的连接,采用了易于存放又避免拆卸拉杆、明显节省操作时间的起重环链。拦污栅前布置液压清污抓斗进行清污。溢流坝检修闸门采用叠梁闸门,使用简易门机起吊。