Determination of Deformation Modulus for Lower Sands in Nakdong River Delta

The deformation modulus of sands below 30 m in the Nakdong River Delta was estimated by using various in-situ tests, such as the piezocone penetrometer (CPT), seismic dilatometer (SDMT), and pressuremeter tests (PMT). Disturbed sand samples retrieved at several depths of two boreholes were reconstituted to simulate the in-situ deposited condition using a slurry method. Thereafter, the drained triaxial compression (TX) and the resonant column (RC) tests were also conducted. The elastic modulus obtained through the application of the TX and PMT results to conventional methods led to the underestimation of the in-situ values, because the inherent characteristics of the natural sands were not considered. Thus, the non-linear modulus degradation curves were constructed using the modulus degradation from the TX, RC, PMT, and the in-situ maximum shear modulus from SDMT. Thereafter, the modulus at 25% failure stress strength was re-evaluated. The re-evaluated values from the TX were in good agreement with those from the PMT, using the unloading curves and with the existing empirical equation based on the seismic CPT. Finally, a CPT-compatible empirical formula for the deformation modulus at 25% failure strength was proposed.     

Oceanic gravity by analytical inversion of Hotine's formula

An analytical inversion of the Hotine formula is developed using fast Fourier transform techniques. Detailed mathematical derivations are used to explain the concepts behind the inverse transformation. Three modifications of the analytical inversion of the Hotine formula are compared and tested using both synthetic data from the OSU91A geopotential model and real GEOSAT altimetry data from the Exact Repeat Mission. The stability of this inverse Hotine approach is investigated using simulated data, and numerical tests are done to quantify the stability of this approach. The approach seems to be numerically stable without employing any stabilization technique. Estimated gravity information from GEOSTAT altimetry data is compared to marine gravity data from shipboard measurements in the Orphan Knoll area. The standard deviations and mean values of the differences between satellite and marine gravity disturbances are 8.2 and 2.9 mGal for the planar approximation, 9.2 and 3.7 mGal for the spherical approximation, and 9.5 and 1.9 mGal for the Molodenskii‐like approximation, respectively, indicating that latitude‐dependent errors affect the latter two approximations. Such errors could be eliminated by performing the calculations by the rigorous one‐dimensional fast Fourier transform (FFT) technique, and any data noise could be filtered out by utilizing covariance knowledge about the input geoid undulations and their errors. Simulation studies also showed that the accuracy of the techniques (for all approximations) can reach a root‐mean‐square (RMS) level of only a few mGal when proper treatment of FFT edge effects is employed and a rather wide area of results is disregarded around the edges.     

A probabilistic investigation of infiltration in the vadose zone: proposal for a new formula of infiltration rate

The infiltration rate in the unsaturated zone is analysed from a probabilistic point of view. It is shown that the empirical formulas of Horton and Kostiakov, without apparent physical basis, are explained in a probabilistic approach. Horton's formula reflects a Markovian process contrary to Kostiakov's formula. This approach made it possible to explain why Kostiakov's formula is more powerful than that of Horton. A new equation of infiltration is proposed. The three formulas were compared, for four types of soil, with the model of van Genuchten based on the Richards equation. Copyright © 2006 John Wiley & Sons, Ltd.     

瞬变电磁法矩形线圈自感的精确表达式

在瞬变电磁法(TEM)中,矩形线圈的自感参数主要用于局部导体晚期瞬变电磁场的等效计算和接收线圈固有过渡过程计算以及瞬变电磁仪器研制。目前,在瞬变电磁法教科书中,单匝矩形线圈自感计算公式都是近似的。本文通过积分方法,推导出了长方形及正方形单匝线圈自感的精确表达式以及正方形单匝线圈自感的近似计算公式。经计算,目前使用的近似公式与精确公式相比误差很大,当回线边长为5m时,误差最小为-39.2%,最大为238.85%;当回线边长为200m时,误差最小为-58.87%,最大为219.33%。本文推导的单匝正方形线圈自感近似公式与精确公式相比误差很小,当回线边长为5m时,误差为0.4%;当回线边长200m时,误差为0.26%。     

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富勒烯笼(Fullereae Cages)Cn的结构表达式

 据富勒烯笼C_n的构成特点,将C_n中的六边形划分出不同的晶体化学构型,而后建立六边形聚合度(HPI)的新概念并给出C_n中六边形可能存在的不同组合及数目。由此得出了C_n的结构表达式。     

矿井涌水量计算的非稳定流解析法

目前矿井涌水量预测普遍存在着评价方法简单、机械套用计算公式、或利用应用软件玩模拟游戏等现象,反而对非常适用的非稳定流解析法重视不够。根据非稳定流解析法公式的基本原理,对其在矿井涌水量预测方面的适用性进行了讨论,并以山西省霍州煤电集团公司某煤矿采区水文地质补充勘查报告矿井涌水量预测为例进行了计算,计算结果表明:非稳定流解析法的雅柯布(近似)公式对于煤层底板突水的矿井涌水量预测,较稳定流解析法和传统的类比外推法在理论上更适用,操作上更灵活;与数值法相比,其又具有较好的直观性。在实践中,该方法计算过程清晰,计算结果可靠,具有推广应用价值。     

油气“穿断运移”模式、评价方法与应用——以珠江口盆地恩平凹陷为例

断层对油气藏的控制作用体现在油气藏的形成和演化过程中断层输导油气和封堵油气的双重作用。究竟起哪种作用主要取决于断层不同部位、不同层段封堵能力和输导能力的差异性。本文基于珠江口盆地恩平凹陷大量断层圈闭油藏的实际钻井资料,从断层活动速率、生长指数、泥岩涂抹因子(SSF)、断层泥比率(SGR)等角度建立了油气"穿断运移"模式和定量评价方法。指出对于恩平凹陷新近系圈闭而言,当控圈断层粤海组沉积期的活动速率<10m/Ma或生长指数<1.1、SSF>1.8~2.1或SGR<0.35~0.42时,油气能够横穿断层运移。基于这项研究,预测了恩平凹陷北部隆起带A1、A3、A4和南部隆起带A20等构造控圈断层的侧向开启部位和层段,推动了多个构造的钻探和3个商业油田的发现,证实了油气"穿断运移"模式和评价方法的准确性和适用性,对具有类似地质特征的地区具有良好的理论指导和实践价值。     

钻 井 液 优 化 设 计 系 统

根据钻井液设计要求，用基于范例推理(CBR)和规则推理(RBR)方法完成钻井液的设计。这两种方法并用，能克服各自缺点，很好地完成钻井液的优化设计。     

雷达测雨及其在水文中应用的回顾与展望

简要介绍了雷达测雨的基本原理,对雷达测雨误差及其产生的原因进行了详细分析,并探讨了减少测雨误差的可能措施。在介绍了英国、美国、长江中游雷达网业务系统和阜阳数字雷达测雨试验的基础上,讨论了雷达测雨在水文中应用的前景及发展方向。