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王俊臣 《吉林大学学报(地球科学版)》2004,34(4):592-595
以岩土力学为基础的土坝设计方法,能够定性和半定量地分析坝体和地基稳定性、估算坝体和地基的沉降量,而不能全面分析地基和坝体内部应力应变状态.采用邓肯E-K模型,对水电站坝基和坝体在填筑和蓄水条件下的应力和变形进行了动态模拟计算,结果表明,坝体和心墙垂直和水平变形在竣工和蓄水期均符合规范要求,心墙在蓄水期间不会产生水力劈裂. 相似文献
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采用三维非线性有限单元法对牛牛混凝土面板堆石坝施工期和蓄水期的应力变形进行模拟计算,并结合沈珠江提出的指数型曲线流变模型,采用自行编制的有限元程序对大坝进行了三维流变分析,得到了坝体、面板在各个时期的应力和变形情况,以及堆石流变对坝体应力变形的影响;计算面板和周边缝位移时采用了三维子模型法,根据实际的坝体填筑、蓄水过程,对每一期面板浇筑之前的坝体上游面位移进行修正,并通过在面板与堆石体之间设置三维面-面摩擦接触单元,来有效模拟面板的应力、变形,为该坝的进一步优化设计提供了有益的建议。 相似文献
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结合实测资料和有限元方法分析建于深覆盖层地基上面板堆石坝的应力、变形特性。数值计算中采用邓肯-张E-B模型模拟覆盖层地基和坝体的应力、变形行为,同时采用无厚度接触面模拟面板和坝体以及防渗墙和地基之间的相互作用。整理和分析工程实测资料并与数值计算结果进行对比分析,重点分析坝体和防渗结构的力学行为以及面板堆石坝和地基之间的相互作用。比较分析表明,大坝最大沉降和压应力分别发生在坝体底部和覆盖层中,覆盖层对坝体及防渗结构的应力、变形特性具有显著影响,应力、变形实测值与数值计算结果吻合较好,说明数值计算结果的有效性。在此基础上,分析了覆盖层上面板堆石坝分期填筑和筑坝速度对坝体和防渗结构应力变形的影响。结果表明,分期填筑引起坝体较大不均匀沉降和复杂的应力状态,但一定程度上可以改善防渗墙的应力变形特性;较快的坝体填筑速度容易引起坝体较大的前期应力和后期沉降,不利坝体的施工和运行。 相似文献
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《岩土力学》2017,(7):2087-2095
深厚覆盖层坝基潜蚀不一定导致坝基的渗透破坏。但坝基砂砾石土内部细颗粒的流失,一方面会增大土体的渗透性;另一方面可降低土体的强度和变形模量。前者导致坝基坝体渗流场的变化,从而引起坝体变形和应力变化,后者变形模量衰化,导致坝基坝体变形和应力调整。潜蚀造成的坝基和坝体应力变形对大坝的正常使用和安全性带来一定负面影响,定量评估这种影响是内部不稳定砂砾石深厚覆盖层坝基采用悬挂式防渗墙处理方案设计和该类大坝运行管理的迫切需求。提出了潜蚀对大坝应力变形影响的模拟方法,对一个典型大坝设计方案进行了计算分析,该设计方案中潜蚀造成应力变形变化的两种机制中,渗流场变化机制对坝基坝体的应力变形改变远大于模量衰化造成的影响。总体上该方案潜蚀造成的坝体变形和应力变化并未显著降低坝体的安全性。 相似文献
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铁矿尾矿料力学特性及坝体变形稳定性研究 总被引：1，自引：0，他引：1
尾矿料矿物成分复杂,物理力学特性区域差异性大。本文以西南地区某铁矿拟建尾矿库为研究对象,对粗、细两种尾矿料进行了系统的物理力学特性试验,获得了粗细尾矿料物理力学指标并应用到尾矿库坝数值分析,分析了该尾矿库坝的应力变形特性,对不同堆积高程、不同工况下尾矿库坝的安全稳定性进行计算分析。此外采用拟静力法对地震荷载作用下尾矿坝的稳定性进行分析。结果表明,粗尾矿料会呈现出剪胀和软化力学特性,而细尾矿料则无明显剪胀;尾矿坝坝体内以压应力为主,坝体表面出现小范围拉应力区;高堆积高程,坝体倾向于发生深层滑动,坝体最小安全稳定性系数较大;干滩长度增大明显提高坝体稳定性;最后对该尾矿库的安全运行提出了一些针对性措施及建议。 相似文献
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整体式折线重力坝的深层抗滑稳定及加固研究 总被引：3，自引：0，他引：3
分别采用三维弹塑性有限元法和分项系数法,对非整体式和整体式折线重力坝的应力和深层抗滑稳定性进行了计算分析,得出整体式折线重力坝有效地改善了坝体的应力和变形状态,但对提高抗滑稳定性不一定有效的结论,并通过拱梁分载法解释了上述结论。采用高压旋喷灌浆进行加固,并提出了较优的加固范围。 相似文献
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通过对一个100 m高典型硬填料坝的应力变形分析,指出坝体填筑过程和硬填料随龄期和应力状态变化的应力-应变特征的模拟对坝体应力变形结果影响显著不容忽略。采用二元本构模型和仿真计算方式,研究了地基弹性模量对坝体应力和强度安全性的影响。地基的变形对坝体应力有显著的影响。地基弹模较低时与较刚性地基的坝体应力情况差异很大。地基弹模较低时,竣工期坝基面中部的拉应力和坝址与坝踵处的压应力都很大,可能并不满足抗拉和抗压强度。与竣工期相比,挡水期坝基面的压应力增加,拉应力减小,抗压强度安全性减小,抗拉强度安全性增加。对于硬填料坝,竣工期和挡水期的抗剪强度安全系数均很高,一般可不进行抗剪强度的计算。 相似文献
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Guillaume Larocque Pierre Dutilleul Bernard Pelletier James W. Fyles 《Mathematical Geology》2007,39(3):263-288
Coregionalization analysis has been presented as a method of multi-scale analysis for multivariate spatial data. Despite an
increasing use of this method in environmental and earth sciences, the uncertainty associated with the estimation of parameters
in coregionalization analysis (e.g., sills and functions of sills) is potentially high and has not yet been characterized.
This article aims to discuss the theory underlying coregionalization analysis and assess the robustness and limits of the
method. A theoretical framework is developed to calculate the ergodic and fluctuation variance-covariance matrices of least-squares
estimators of sills in the linear model of coregionalization. To adjust for the positive semidefiniteness constraint on estimated
coregionalization matrices, a confidence interval estimation procedure for sills and functions of sills is presented. Thereafter,
the relative importance of uncertainty measures (bias and variance) for sills and structural coefficients of correlation and
determination is assessed under different scenarios to identify factors controlling their uncertainty. Our results show that
the sampling grid density, the choice of the least-squares estimator of sills, the positive semidefiniteness constraint, the
presence of scale dependence in the correlations, and the number and range of variogram models, all affect the level of uncertainty,
sometimes through multiple interactions. The asymptotic properties of variogram model parameter estimators in a bounded sampling
domain impose a theoretical limit to their accuracy and precision. Because of this limit, the uncertainty was found to be
high for several scenarios, especially with three variogram models, and was often more dependent on the ratio of variogram
range to domain extent than on the sampling grid density. In practice, in the coregionalization analysis of a real dataset,
the circular requirement for sill estimates in the calculation of uncertainty measures makes the quantification of uncertainty
very problematic, if not impossible. The use of coregionalization analysis must be made with due knowledge of the uncertainty
levels and limits of the method. 相似文献
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本文采用流量级频率分析和统计分析方法,对黄河下游流量及泥沙含量对水环境容量的影响进行了研究分析.分析结果:河流在平滩流量时不仅输沙能力最大[8],而且输运污染物能力也最大,黄河下游水环境容量萎缩是平滩流量降低的必然结果. 相似文献
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The world’s present demand for oil and gas is still in a rapid growth period, and traditional oil and gas resources account for more than 60% of the global oil and gas supply. The Americas is the world’s second largest production and consumption center of liquid fuel, and is also the world’s largest natural gas producer. In 2016, the Americas had 85.3 billion tons of proven oil reserves and 18.7 trillion m3 of proven natural gas reserves, which account for 35.4% and 10.0% of world’s total reserves, respectively. It produced 1267.1 Mt of oil and 1125.4 billion m3 of natural gas, which account for 28.9% and 31.7% of the world’s total production, respectively. The crude oil and natural gas reserves are mainly distributed in the U.S., Canada and Venezuela. The U.S. is the earliest and most successful country in shale gas exploration and development, and its shale gas is concentrated in the southern, central and eastern U.S., including the Marcellcus shale, Barnett shale, EagleFord shale, Bakken shale, Fayettevis shale, Haynsvill shale, Woodford shale and Monterey/Santos shale. The potential oil and gas resources in the Americas are mainly concentrated in the anticline and stratigraphic traps in the Middle-Upper Jurassic slope deposition of the North Slope Basin, the Paleozoic Madsion group dolomite and limestone in the Williston Basin, dominant stratigraphic traps and few structural traps in the Western Canada Sedimentary Basin, the Eocene structural-stratigraphic hydrocarbon combination, structural-unconformity traps and structural hydrocarbon combination, and the Upper Miocene stratigraphic-structural hydrocarbon combination in the Maracaibo Basin of Venezuela, the stratigraphic-structural traps and fault horst, tilting faulted blocks and anticlines related to subsalt structure and basement activity in the Campos Basin, the subsalt central low-uplift belt and supra-salt central low-uplift belt in the Santos Basin of Brazil, and the structural-stratigraphic traps in the Neuquen Basin of Argentina. In addition, the breakthrough of seismic subsalt imaging technology makes the subsalt deepwater sea area of eastern Barzil an important oil and gas potential area. 相似文献
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地层温、压是油气成藏环境的能量参数,影响着油气从生成、运聚、调整,直至逸散的整个过程。前人研究多注重温度对油气生成、压力对油气运移的控制作用,对温度在油气运移、聚集中的作用还没有系统的研究。作者通过对油气运移、聚集过程中所发生的物理、化学及物理化学作用分析,明确了地层温度在其中所起的作用。对油气运移,一方面,地层温度非均匀变化引起的热应力,可以直接为油气运移提供驱动力;另一方面,地层温度通过改变分子粘度、表面张力、溶解度等物性参数影响油气运移能力。对于油气聚集,地层温度(和地层压力等)不仅影响和制约油气的分布位置,还通过控制有机质演化进程、影响烃类流体相态分异,来影响油气的聚集特征。最后还对地层温度控藏中存在的问题进行了探讨,认为地层温度与地层压力、构造应力等因素存在一定内在联系并共同控制油气成藏,在分析地层温度对各成藏阶段的影响时应恢复相应时期的地温场。 相似文献
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河北省矿产资源和开发利用存在的主要问题及对策 总被引：4，自引：0，他引：4
徐荣校 《华北地质矿产杂志》1999,(2)
矿产资源问题是直接影响可持续发展。本文围绕矿产资源不足和浪费严重两个核心问题,从11个方面揭露出22个问题,并对问题产生的原因作了简要分析。同时有针对性地提出了“开源”、“节流”、“增效”等3个方面10条对策和建议,为矿业发展战略和决策提供了可靠依据。 相似文献