孕震过程中冲流电位地电异常的理论研究

分别计算了具有对称压力源分布的水平层状半空间介质模型和各向异性裂隙模型的地表冲流电位异常．结果表明，本文所采用的模型计算出来的地表冲流电位异常最大值的量级是合理的，其幅度最大约为几百毫伏；异常范围随地下各向异性强烈程度而变化．同时，在计算地表冲流电位异常时引入了各向异性裂隙的概念，从而从理论上解决了实际观测与理论不相符合的矛盾．      

动态致裂过程的能量分析

本文从能量观点出发,对裂纹形成过程进行了分析,并以此为基础,讨论了各种致裂方法的原理和特点。     

具有孔边裂纹的岩石厚壁筒试件的破裂特征

用五种应力途径对由五种岩石制备的孔边有予裂纹的厚壁筒试件进行实验,研究上述条件下岩石的破裂特征。结果表明:对含径向并贯穿轴向裂纹的试件,其破裂沿裂纹方向,为典型的张开型破裂;含与定直径成45°角并贯穿轴向裂纹的试件,破裂亦呈张开型,其裂面始于裂纹前缘,但却折转约45°角与定直径近于平行;中心含与轴向成45°角的椭圆裂纹试件的破裂,仍沿裂纹面方向,为张开型与滑开型的复合破裂。     

氯氧镁水泥在特定水环境中的强度变化规律试验研究

为了研究氯氧镁水泥(MOC)试件分别在老卤、原卤、海水和淡水4种水环境中的强度变化规律,以掺加一定量复合改性剂MOC为基体,将其养护28d后,分别置于老卤、原卤、海水和淡水中浸泡一定期龄,分析其在4种特定水环境中的强度变化规律。实验结果表明,MOC试件在4种特定水环境中抗压强度变化规律不同。相较于在空气中养护,MOC在老卤、原卤、海水和淡水浸泡下,抗压强度有不同程度的降低,其在4种水环境中降低程度依次为:淡水海水原卤老卤。经4种特定水环境浸泡3个月后,MOC抗压强度保留相在老卤中最高,其抗压强度保留相高达95.60%,证明MOC试件在老卤中具有较好的抗盐卤腐蚀性能。     

甘肃黑方台地区灌溉型黄土滑坡形成机理与运动学特征——以焦家崖头13号滑坡为例

甘肃黑方台地区常年农业灌溉导致塬边产生大量的黄土滑坡,灌溉水长期入渗引起灌区地下水位上升,园地下水作用造成水敏性黄土遇水乃至饱水后强度劣化．进而产生斜坡失稳,因黄土滑坡剪出口高悬于上缓下陡的坡体中部,其成灾模式呈现出高位剪出后高速滑动．并产生远程运移,波及范围大,致灾后果严重。以甘肃省永靖县黑方台焦家崖头滑坡为例,在现场调查和地下水动态监测的基础上,对灌溉型黄土滑坡塑流-拉裂形成机理进行分析,并运用离散元模拟方法,对地下水位上升过程中模型底部饱水黄土软弱层的形成、演化过程和滑坡运动学特征进行模拟研究。结果表明,随地下水位的上升,模型底部软弱层范围不断增大：孔隙水压力主要作用于滑坡底部软弱层饱水黄土：地下水位高程上升至标高1682m时,滑坡产生整体破坏。     

辽河断陷源内油气资源潜力分析

辽河油田经过50余年以寻找圈闭为主的源外油气勘探开发,取得了丰富的成果。1986年突破年产原油10.0 Mt大关,成为中国第三大油田。进入21世纪以来,油田产量逐年下降,稳产难度越来越大。为了确保油田持续稳定发展,积极拓展勘探视野,寻找新的后备勘探领域,提出了油田发展的巨大潜在资源——源内油气资源的勘探新思路。可望带来新一轮油气储量和产量增长高峰。源内油气资源是相对于源外油气资源的概念而提出的。源内油气资源就是滞留在烃源岩中尚未排出或难于排出的油气资源。在长期的源外石油勘探工作中,摸索、总结了一套具有指导意义的石油地质理论和较成熟的勘探、开发技术系列,有效地勘探开发了地下的油气资源。源内石油勘探,是对油田发展和国家能源战略安全的前瞻性思考。但这是一个难度较大、常人难以理解的新领域和新观念!特别是面对目前世界原油价格不断下滑的困难局面,更增加了工作的难度。如能突破对这种新观念的种种束缚和来自方方面面的阻力,积极组织研究源内油气资源的富集和分布规律,开展相应的勘探开发技术攻关,将会带来新一轮油气资源量和储量增长高峰。对油田发展和国家能源战略安全具有重要的现实意义和深远的历史意义。     

A three-phase XFEM model for hydraulic fracturing with cohesive crack propagation

A three-phase hydro-mechanical model for hydraulic fracturing is proposed. Three phases include: porous solid, fracturing fluid and host fluid. Discontinuity is handled using extended finite element method (XFEM) while cohesive crack model is used as fracturing criterion. Flow through fracture is defined as one-dimensional laminar flow, and flow through porous medium (host reservoir) is defined as two-dimensional Darcy flow. Coupling between two fluids in each space, fracture and pore, is captured through capillary pressure–saturation relationship, while the identical fluids in fracture and pore are coupled through a so-called leak-off mass transfer term. Coupling between fluids and deformation is captured through compatibility of volumetric strain of fluids within fracture and pore, and volumetric strain of the matrix. Spatial and temporal discretisation is achieved using the standard Galerkin method and the finite difference technique, respectively. The model is verified against analytical solutions available from literature. The leaking of fracturing fluid into the medium and suction of porous fluid into the fracture around the tip, are investigated. Sensitivity analyses are carried out for cases with slow and fast injection rates. It is shown that the results by single-phase flow may underestimate the leak-off.     

基于多分辨率半边的三维地形自适应无缝建模

"限定四叉树"法可以实现三维地形自适应无缝建模,但仍存在一些问题,如计算量大、数据冗余等。该文将多分辨率半边理论引入到三维地形建模中,提出了适合自适应地形格网存储和格网面提取的方法;设计并实现了三维地形自适应无缝建模的算法;最后,应用C语言和DirectX工具,开发了相应的可视化实验系统。与"限定四叉树"法相比,该方法不需要反复检测相邻格网的层差,且随剖分层次的增加,格网数量和渲染数据量的降低率逐渐增大,分别达13.9%和12.2%(剖分层次为7)。     

Generation and Application of A Standardized Load-Time History to Tubular T-joints in Offshore Platforms

Marine structures are mostly made of metals and always experience complex random loading during their service periods. The fatigue crack growth behaviors of metal materials have been proved from laboratory tests to be sensitive to the loading sequence encountered. In order to take account of the loading sequence effect, fatigue life prediction should be based on fatigue crack propagation (FCP) theory rather than the currently used cumulative fatigue damage (CFD) theory. A unified fatigue life prediction (UFLP) method for marine structures has been proposed by the authors’ group. In order to apply the UFLP method for newly designed structures, authorities such as the classification societies should provide a standardized load-time history (SLH) such as the TWIST and FALSTAFF sequences for transport and fighter aircraft. This paper mainly aims at proposing a procedure to generate the SLHs for marine structures based on a short-term loading sample and to provide an illustration on how to use the presented SLH to a typical tubular T-joint in an offshore platform based on the UFLP method.     

老龄半潜式钻井平台节点疲劳裂纹扩展寿命预报

通过结合常规谱疲劳分析方法和裂纹扩展分析方法,给出了一种工程实用的评价老龄平台节点裂纹扩展寿命的方法,并以某一平台为例进行了验证计算。首先,基于谱疲劳分析得到各个节点在过去30年的节点疲劳损伤,然后,对损伤接近或大于1.0的节点进行基于单一曲线模型的裂纹扩展分析,以求得该节点在目前状态下裂纹扩展寿命。结果表明,目标平台计算疲劳热点满足继续使用的要求。此外,针对不同初始裂纹尺寸时的裂纹扩展寿命计算结果表明初始裂纹尺寸对疲劳裂纹扩展寿命影响很大。