黏土中自升式钻井船插桩对邻近桩基影响的分析方法     

李亚  李书兆  张超 《岩土力学》2018,39(5):1891-1900

自升式钻井船是广泛用于浅、中水域油气资源开发的重要设施,经常紧邻固定式导管架平台进行作业。钻井船插桩就位过程中大量土体被排开,挤土效应会导致邻近导管架平台桩基承受很大的附加荷载,影响平台的正常设计性能,该效应在黏土中尤为显著。针对黏土中钻井船插桩对邻近桩基的影响这一实际问题,现有规范和分析方法存在明显不足。为此,建立了一套数值分析方法,把这一复杂问题分解成相对独立、简单的两个方面进行分析：一是采用任意拉格朗日-欧拉（ALE）数值方法,计算自由场地插桩周围土体产生的位移场;二是利用桩基水平力与位移关系曲线,即P-Y曲线,采用杆系-土弹簧的传统方法计算土体位移产生的桩体加载。通过与已有离心试验数据的比较,验证了该方法的可靠性和适用性。研究揭示了自由场地土体的变形模式和流动机制,阐明了由于插桩邻近桩基产生的附加荷载变化规律,特别是发现了黏土变形参数 对插桩引起的自由场地土体位移场有显著影响,但对插桩引起的桩基加载影响较小。最后,针对导管架对桩基的桩头约束条件和插桩及导管架自身对桩基的线性叠加加载适用性问题给出了详细说明。  相似文献   

断层带震相及其应用研究现状与展望     

郑建常 《中国地震研究》2014,(4):413-424

Deep structure and material properties of faults can be understood by observing and simulating the particular phase in a fault fracture zone. This paper reviews the development of fault-zone seismic waves in the seismological domain. The present research status of fault-zone head wave and trapped wave are summarized systematically. Based on recent progress in this field, the paper discusses the prospect on the utilization of seismic wave in fault structure research.  相似文献   

Implications of subsurface thermal–hydraulic–mechanical processes associated with glaciation on Shield flow system evolution and performance assessment     

Tin Chan  Frank W. Stanchell 《Environmental Geology》2009,57(6):1371-1389

A deep geologic repository (DGR) situated on the Canadian Shield will be subject to long-term climate change that will markedly alter surface conditions as a result of glaciation and permafrost penetration. Systematic, two-dimensional and three-dimensional coupled thermal–hydraulic–mechanical finite-element simulations with varying degrees of coupling, including depth-dependent salinity (represented as a change in groundwater density) and temperature-dependent density and viscosity, were undertaken to address the implications of glaciation on groundwater flow system dynamics as it could affect DGR performance. The modelling domain consisted of a 1.6-km deep sub-regional scale (≈100 km²) fractured Shield flow system. Initial and transient thermal, hydraulic and mechanical boundary conditions were developed from two realizations of the University of Toronto Glacial Systems Model of the last Laurentide glaciation. Results indicate that during the glacial loading/unloading cycle, for this particular conceptual model, there is limited penetration of glacial meltwaters to depth and small residual anomalous hydraulic head. During glacial coverage, the mechanical factor of safety increases in the moderately fractured and sparsely fractured rock mass, but principal effective stress reorientation also occurs. Given the assumed nonglacial in situ state of stress and mechanical properties, the fracture zones were predicted to be less stable under glacial conditions.

Tin ChanEmail:

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静水压力取样器冲击头冲击速度的理论与试验研究     

秦华伟  朱敬如  王建军  陈建桥  陈鹰 《海洋工程》2013,31(2):68-73

介绍了一种用于海底沉积物取样的静水压力取样器,它能依次利用重力势能和静水压力能,将其转换为冲击动能,以冲击形式将取样管插入海底沉积物进行取样。结合既定取样器对其冲击头的冲击速度进行了理论推导,并提出相关经验公式。通过取样器冲击试验,验证了静水压力取样器冲击头冲击速度理论模型的正确性和合理性。在理论推导和实验验证的基础上,对影响取样器冲击头冲击速度三个主要因素进行了探讨,并提出了提高冲击头冲击速度的具体措施。  相似文献   

头颈部结外淋巴瘤的影像诊断     

张建新  杨晓棠  王艳艳  陈麦林  王峻 《CT理论与应用研究》2012,21(2):269-276

目的:探讨头颈部结外淋巴瘤的CT、MRI表现及临床病理特点。方法:回顾性对照分析51例经外科手术或病理证实的头颈部结外淋巴瘤患者的临床病理及CT、MRI影像资料,评价头颈部结外淋巴瘤的影像及临床病理特点。结果:51例全部为非何杰金淋巴瘤(NHL),其中来源于B细胞32例(62.75%),T细胞19例(37.25%)。原发部位最常见于鼻腔及咽环,其中鼻腔23例(45.10%),咽环(Waldeyer环)20例(39.22%),其余部位共8例(15.69%),包括眼眶3例,喉部、甲状腺各2例,腮腺1例。18例(35.29%)伴淋巴结转移。根据肿瘤形态分为3型,其中单发肿块型31例(60.78%),弥漫肿胀型17例(33.33%),溃疡坏死型3例(5.89%)。结论:头颈部结外淋巴瘤的临床病理及CT、MRI影像表现有一定特征性,影像检查可以显示病变形态、范围及淋巴结转移,结合临床特点对头颈部结外淋巴瘤的诊断、分期及指导治疗有一定价值。  相似文献   

深海底钻机动力头的钻杆自行抛弃和冲击卸扣机构          下载免费PDF全文

魏治利  钟路  谢振权  臧龙  彭莹 《探矿工程》2017,44(10):84-87,83

文章介绍了深海岩心取样钻机的主要部件动力头的结构及特点。根据深海钻进的特殊情况,专门在动力头上设计了钻杆自行抛弃机构和冲击卸扣机构。这两种机构可在发生卡钻事故钻机无法回收已经深入孔内的钻杆串时,可将其自行抛弃,或由于动力头扭矩液压马达出现故障不能拧卸钻杆时,冲击卸扣机构将对钻杆丝扣进行冲击使其松动而卸扣。文章重点介绍了钻杆自行抛弃机构和冲击卸扣机构的结构及工作原理。  相似文献   

Head/Tail Breaks: A New Classification Scheme for Data with a Heavy-Tailed Distribution   总被引：2，自引：0，他引：2  

Bin Jiang 《The Professional geographer》2013,65(3):482-494

This article introduces a new classification scheme—head/tail breaks—to find groupings or hierarchy for data with a heavy-tailed distribution. The heavy-tailed distributions are heavily right skewed, with a minority of large values in the head and a majority of small values in the tail, commonly characterized by a power law, a lognormal, or an exponential function. For example, a country's population is often distributed in such a heavy-tailed manner, with a minority of people (e.g., 20 percent) in the countryside and the vast majority (e.g., 80 percent) in urban areas. This new classification scheme partitions all of the data values around the mean into two parts and continues the process iteratively for the values (above the mean) in the head until the head part values are no longer heavy-tailed distributed. Thus, the number of classes and the class intervals are both naturally determined. I therefore claim that the new classification scheme is more natural than the natural breaks in finding the groupings or hierarchy for data with a heavy-tailed distribution. I demonstrate the advantages of the head/tail breaks method over Jenks's natural breaks in capturing the underlying hierarchy of the data.  相似文献   

A channel head stability criterion for first‐order catchments     

Péter B. Sólyom 《地球表面变化过程与地形》2011,36(4):533-546

The present analysis derives a stability criterion for long‐term equilibrium channel heads. The concept of finite perturbation analysis is presented, during which the surface is subjected to perturbations of a finite amplitude and resulting changes in flow path structure and slope are computed. Based on these quantities the analysis predicts whether the perturbed location is going to erode, be filled in or remain steady. The channel head is defined geometrically as the focus point of converging flow lines at the bottom of hollows. It is demonstrated that stability at the channel head grows out of the competition between the rate of flow path convergence and the degree of profile concavity. Analytical functions are derived to compute channel head‐contributing area and ‐slope, flow path convergence and profile concavity as a function of perturbation depth, distance from the crest and the initial slope. In a numerical model these quantities point to the long‐term equilibrium channel head position, which is shown to depend also on the width to length ratio of hollows. It is also demonstrated that the equilibrium channel head position is sensitive to the base‐level lowering/non‐dimensional slope length ratio and to the slope of the initial topography. Morphometrical measurements both in the field and on simulated topographies were used to test the theoretical predictions.  相似文献   

顶空进样-固相微萃取测定饮用水源水中吡啶   总被引：2，自引：1，他引：1  

赖永忠 《岩矿测试》2011,30(5):596-600

用75μm CarboxenTM-Polydimethylsiloxane(CAR-PDMS)固相微萃取头顶空萃取15 mL水样中的吡啶,萃取物用气相色谱-质谱法进行分离和检测,采用内标法和质谱的选择离子监测模式进行定量分析。优化了顶空进样-固相微萃取条件,获得较佳的萃取温度(58.0℃)和萃取时间(40 min)。在优化的条件下,方法检出限为1.5μg/L,标准曲线的线性相关系数为0.9994,线性范围为2.5～50.0μg/L;饮用水源水和纯水加标平均回收率为75.6%～81.3%,相对标准偏差(RSD,n=6)为9.60%～12.21%。使用顶空萃取方式可避免样品基体的复杂性,有利于保护萃取头涂层,同时无需使用有机萃取溶剂;使用质谱检测器可减小假阳性带来的影响。顶空进样-固相微萃取操作简单、环保、灵敏度高,适合用于饮用水源水中吡啶的监测分析。  相似文献   

基于OLHS随机模拟的地下水源地保护区划分     

徐海珍  李国敏  张寿全  董艳辉  贺国平 《吉林大学学报(地球科学版)》2011,(Z1):259-264,302

为解决确定性模型可能为地下水源地划分带来的保护不足或过保护问题,探索采用基于正交拉丁超立方抽样法的地下水模型研究,并结合粒子反向追踪技术,进行地下水流随机模拟和对应保护区的概率统计分析,最终得到具有分布概率的保护区范围。为验证该方法的实用性与可靠性,选取北京市平谷区王都庄应急水源地进行实例应用研究。在考虑渗透系数和降雨补给量随机抽样组合基础上进行地下水流动随机模拟,并完成对应保护区划分和加权统计。与确定性模拟划分结果相对比:一级保护区中,确定性模拟划分结果仅相当于随机模拟结果中统计概率70%以上的范围;对于二级保护区,确定法对应保护面积相当于随机模拟结果中50%概率以上的范围。实例研究表明,基于正交拉丁超立方抽样的随机模拟法可完成多个不确定性输入变量条件下的随机模拟,且在小样本数的基础上获得理想结果,适用于复杂水文地质条件下的地下水源地保护区划分研究。  相似文献