三峡工程地下厂房随机块体稳定性分析

应用块体理论、正交设计方法对三峡地下厂房围岩中裂隙可能构成的随机块体类型、几何特征与稳定进行了分析。所获结果表明：三峡地下厂房的随机块体的虽然稳定性较好,但最大埋深仍可达7~8 m,为确保围岩的稳定,系统锚杆的支护长度应大于7 m。     

全球气候研究计划 (WCRP)中的气候与冰冻圈项目 (CliC): 冰冻圈与气候的优先研究领域

The cryosphere is an integral part of the global climate system, however, many aspects of the cryosphere have not been fully covered within WCRP. Issues relating to potential changes in the climate cryosphere system become more and more important in order to describes research and coordination initiatives required to integrate fully studies of impact and response of the cryosphere to climate change. The article also indicates the recent progress of CliC, and its future plan.     

堤坝脉动注浆浆液扩散机制及应用研究

基于脉动注浆泵可输出低频周期性脉冲压力的特点,结合可控性黏土固化浆液,提出了一种可用于堤坝防渗加固的新方法。通过进行原型试验验证了该方法的可行性,考虑钻孔扰动和脉动低频重复压力对地层渗透特性的影响,推导了黏土固化浆液脉动扩散方程,运用多场耦合软件COMSOL探讨了脉动压力下黏土固化浆液扩散的机制,最后将研究成果成功应用于南水北调中线鹤壁段引水渠道边坡帷幕注浆工程。研究结果表明：黏土固化浆液脉动控制注浆技术可显著提高地层连续性和整体性,结石体28 d强度大于2 MPa,渗透系数可降至10?5 cm/s左右,浆液在注浆孔附近与土体胶结成块,邻近注浆孔浆脉交错搭接,整体表现为空间立体网状包裹结构的防渗墙体;对数值模拟和现场试验结果进行综合分析,堤坝脉动注浆时间应控制在1 800～2 400 s之间,合理的脉动注浆压力在0.2～2 MPa之间,脉动持续时间宜调至4～8 s,脉动间隔时间宜调至2～6 s,这样有利于保证堤坝脉动注浆工程达到最优的防渗加固效果;工程实践的渠道边坡连续性、整体性得到了改善,注浆止水加固效果显著,检查孔渗透系数降至10?5 cm/s,所取芯样完整,芯样最长可达40 cm。     

滑坡稳定性变化与地下水非稳定渗流初探--以三峡库区黄蜡石滑坡群石榴树包滑坡为例

把滑坡体离散化为一定数量的条块,基于水均衡原理建立了滑坡体地下水一维非稳定渗流的差分方程组,其中考虑了滑坡体地下水通过弱透水滑动带的越流排泄,对动态边界提出了处理方法.以三峡库区黄蜡石滑坡群的石榴树包滑坡为例,根据三峡水库蓄水前和蓄水后排泄区的不同水位条件,模拟了在强降雨过程中滑坡地下水的动态过程.结合考虑地下水渗透力的传递系数法,计算了石榴树包滑坡稳定性系数随时间的变化,结果表明无论是在三峡水库蓄水前还是蓄水后的极端降雨条件下石榴树包滑坡都是不安全的.在地下水非稳定渗流的影响下,滑坡稳定性对降雨和排泄区水位的响应具有滞后性.     

水布垭面板堆石坝流变影响研究

采用9参数流变模型对水布垭面板堆石坝堆石料的流变影响进行了分析和研究,并从试验角度对堆石料流变变形机理进行了初步探讨。计算结果表明,三维仿真计算的典型部位的大坝沉降变形历时曲线与实测沉降资料比较吻合,验证了9参数流变模型的有效性、可行性。     

南水北调东线工程对东平湖水环境的影响

为考察南水北调东线工程对东平湖水环境的影响,为受水区域的用水安全提供保障,于东线工程通水前后分别采集不同水文时期的东平湖湖水样品,分析测定后,采用综合污染指数法、综合营养状态指数法、健康风险评价模型,评价东线工程通水前后东平湖湖水水质级别、营养化水平和健康风险水平的差异。结果表明:东线工程通水后,东平湖湖水综合污染指数由通水前的0.49变为通水后的0.58,水质级别仍为Ⅲ级轻度污染,部分指标超标但不严重;综合营养状态指数由通水前的50.72降为通水后的47.90,表明营养化水平由轻度富营养状态好转为中营养水平;健康风险由通水前的2.91×10~(-4)a~(-1)降为通水后的9.35×10~(-5)a~(-1),即由通水前的中—高风险水平降低为通水后的中风险水平。结论可知,南水北调东线工程的通水有利于东平湖湖水环境的改善,但与其他典型淡水湖泊相比,东平湖湖水的健康风险仍相对偏高,后续需要进一步加强湖区环境保护和污染排放的管控。     

地质雷达在三峡工程施工应用研究

长江三峡工程施工阶段面临众多复杂的工程地质问题和施工技术难题,寻找一种快捷、高分辨无损探测手段查明施工中出现的隐蔽的地质缺陷或质量问题,无疑对施工进度和施工质量起到保证作用,采用地质雷达手段,探明了开挖过程中花岗岩体不均匀风化分布范围：圈定出较大断层及风化夹层的延伸范围和产状：并进行了专用高速公路质量检查等,文章结合三个实例介绍应用情况。经现场验证,探测结果与实际情况吻合,应用效果显著。     

三峡大坝深层抗滑稳定研究

三峡左岸厂房1～5号机组坝段存在高陡边坡沿缓（中）倾角结构面的深层滑动稳定问题,对坝基和高陡边坡稳定十分不利。根据实测的长大缓倾角结构面的分布,概化出各坝段的确定性滑移模式,并提出了两种假定的、极端的滑移模型。从工程结构措施、稳定分析方法以及监测资料分析等几个方面,探究了工程稳定性问题,校核和验证了大坝的稳定安全。分析方法主要采用刚体极限平衡法,同时辅以有限元数值分析与地质力学模型试验。左厂1～5号坝段按刚体极限平衡法求得的K′c值满足稳定安全的判据的要求,用其它分析方法：有限元法分析的K′c在3.0～4.5以上,地质力学模型试验,超载系数为3.5～4.2,表明左厂1～5号坝段在采取了各种工程结构措施后大坝及其岩基的抗滑稳定已有保证。     

Settlement and slaking problems in the world's fourth largest rock-fill dam, the Ataturk Dam in Turkey

The Ataturk Dam is the fourth largest clay cored rock-fill dam in the world. Located in southeastern Turkey, it is the centrepiece of a project called the Southeastern Anatolian Project (GAP). The construction of the dam was finished in the short time of 3 years and 8 months in August 1990. As the reservoir level started to rise, settlement problems started to occur along the crest reaching considerable levels by May 1992 and the weathered vesicular basalt used in the rock-fill section of the dam started to slake seriously. The elevation of the crest has fallen down to such an extent that now the upper part of the dam is being reconstructed to the original height of 549 m in order to maintain the 7 m freeboard and keep the dam operational. The settlement and slaking problems of the dam were investigated both in the field and the laboratory using soil and rock mechanical techniques. Standard proctor tests were run to determine the optimum moisture content at which the highest dry density (best compaction) is obtained during compaction of the impervious clay core. Consolidation tests were performed on undisturbed compacted clay core samples to determine if the field compaction of the clay core was done to the standards determined in the laboratory. Unconfined compression tests were run on the two different (sound aphanitic and weathered vesicular) basalts used in the rock-fill section of the dam to determine their unconfined compressive strengths. Slake durability tests were run on the same basalts to determine their durability under wetting and drying cycles. Petrographic and X-ray analysis were done so as to study the mineralogical contents of the two basalts and in turn, to determine the cause of rapid slaking of the vesicular textured weathered basalt. The consolidation test results show that, the field compaction of the impervious clay core of the dam was not done to the standards determined through the proctor tests in the laboratory. The unconfined compressive strength of the sound aphanitic basalt is more than ten times greater than the weathered vesicular basalt, and while the former has extremely high durability the latter only has medium durability. Because of nontronite (iron montmorillonite) and secondary calcite amygdules filling the vesicles, the weathered vesicular basalt used in the rock-fill section is slaking badly causing additional settlement and landslides both in the clay core which is already settling and the rock-fill section of the dam. With the continuing slaking, the present reconstruction of the crest up to the theoretically intended height of 549 m to maintain the 7 m freeboard and keep the dam operational seems only to be a temporary solution.     

Peaceful Nuclear Explosions and the Geography of Scientific Authority

From 1957 to 1973, scientists and engineers working under the direction of the United States Atomic Energy Commission and its Livermore laboratory investigated, experimented with, and promoted the idea of ‘peaceful’ uses of nuclear explosives through a program called Project Plowshare. Proponents confidently argued that the ‘geographical engineering’ (as it was called) of harbors, canals, dams, and mountain passes could be accomplished safely, economically, and scientifically by means of nuclear‐blasted excavation. But the nuclear earthmoving explosions also produced large amounts of radioactive fallout, and with it, significant challenges to the program on scientific grounds. This paper examines several moments from the contested career of nuclear earthmoving to show how scientific and technical research under the Plowshare program, developed out of the resources of Cold War American science, was structured by geographical variations in scientific authority.