两种突水系数计算公式的比较

《煤矿床水文地质、工程地质及环境地质勘查评价标准》和《煤矿防治水规定》中各给出了一个突水系数计算公式,分别称为公式（1）和公式（2）。比较发现,两个计算公式在参数的选择、规定的正常块段的l临界突水系数、安全系数、使用的方便程度4方面是不同的,并逐一进行了分析。然后以山西省临县新民煤矿1井田9号煤层的开采为例,进行了突水系数的计算。结果表明,采用公式（1）计算出的突水系数大于采用公式（2）计算出的突水系数;采用公式（1）计算,井田范围内9号煤开采全部处在带压开采临界区内;采用公式（2）计算,井田南部有一部分范围9号煤开采处在带压开采安全区内,井田北部大部分范围9号煤开采处在带压开采临界区内。最后指出．在计算突水系数时,水文地质条件简单、含水层富水性较弱、补给条件差的矿区,选择公式（1）;水文地质条件复杂、含水层富水性较强、补给条件好的矿区．可以选择公式（2）。     

受控三轴应力-应变下沉积物声速与物理力学性质的关系

对南海某海域深度100～400 m的海底浅层（约2 m埋深范围）沉积物柱状样在接近海底水压力下进行三轴应变-声学同步测量,结果表明沉积物纵波声速有两个特征:（1）从应变过程开始到结束,沉积物纵波声速不断变化;（2）平均声速随着平均静弹性模量的增加,由大变小又由小变大,存在声速最小值。这些结果与海底浅表层沉积物的物理力学性质、围压、颗粒的结合状态改变有关。此外,沉积物动弹性模量和孔隙度呈良好的负相关性,这与孔隙度增大含水量增大有关;动弹性模量是静弹性模量的10～100倍,这主要与三轴应变试验的应变数量级与声波振动产生的应变数量级的差异大有关。采用本论文实验测量的数据分别建立了双复合参数-声速和孔隙度-声速经验公式,分析结果表明双复合参数-声速公式声速预报误差约是孔隙度-声速公式的1/4,表明双复合参数-声速公式更加有效。     

Fracture modes in the Silurian Qusaiba Shale Play,Northern Saudi Arabia and their geomechanical implications

Fracture and in-situ stress studies were conducted for unconventional prospect evaluation in the Silurian Qusaiba Shale, northern Saudi Arabia. Borehole image logs, oriented cores, seismic, and drilling observations were used in the studies. The fractures include natural fractures and induced fractures. The induced fractures were studied to assess the stress regime in terms of directions and magnitudes. The present day maximum horizontal in-situ stress trend varies from NNW-SSE to NNE-SSW, and shows a regional pattern dominated by Arabian plate tectonics. The relative magnitudes of the current day stresses are characteristic of an extensional to strike-slip regime. Natural fractures of microscopic (microfractures) to macroscopic (macrofractures) scales include extension fractures (joints/veins), and faults manifested as shear and hybrid (extensional-shear and compressional-shear) fractures. Joints clustering into zones are rare, unless when associated with fault zones. Over half of the faults (56%) show clustering into fault zones with their widths (thickness) varying by up to 5 orders of magnitude, and lengths and displacements varying by up to 4 orders of magnitudes respectively. The study identified five distinctive, regional, fracture sets: one gently dipping (bedding-parallel or at low angle to bedding) and up to four moderately to steeply dipping fracture sets: an easterly striking set is the oldest, followed by three younger major sets striking NNW-SSE, N-S, and NNE-SSW. The younger fractures are nearly parallel to the present day maximum horizontal in-situ stress. Crack-seal mechanism (natural hydrofracturing) dominates initial fracture growth, some with several phases of partial to complete mineralization or coating, dominated by calcite, quartz, and dolomite. Aqueous and hydrocarbon gaseous and fluid inclusions are common in the fractures' mineral filling. The regional nature of in-situ stresses and natural fractures means their occurrence, orientation, relative dominance, and relative age and relative apertures are easier to predict and manipulate for well planning and completion, including hydrofracturing. Forward modeling shows that natural fracture network are not critically stressed under reservoir conditions but when subjected to massive hydrofracture stimulation they and the bedding discontinuities form the seeds for the growth of a complex hydrofracture network that potentially grows out of presumed stress-barriers. Lack of stress rotation around faults in wells supports the modeling results. Microseismic monitoring gives time-lapse (incremental) microseismic events of two types; random and linear patterns parallel to maximum horizontal in-situ stress and the predominant natural fracture trend. Bulk microseismic cloud has no unique link to fault trends mapped from high resolution borehole images. This finding challenges the usability of uncalibrated microseimic monitoring of massive hydrofracturing to map faults.     

基于全角半距法钻孔偏斜距离计算公式的推导

钻孔弯曲的偏斜距离是地质钻探工程质量的一项重要指标。介绍了钻孔弯曲及钻孔弯曲计算模型中最常用的全角半距法。通过基于三维坐标系的钻孔轴线上各测点的空间位置的描述,借助于立体几何的方法,推导出钻孔中任一深度处偏斜距离的计算公式,讨论了顶角和方位角的变化对偏斜距离的影响程度,给出了一计算实例。     

北京地区地基GPS加权平均温度计算本地化模型研究

利用中国区域内93个无线电探空站2005-2010年的探空数据,分析加权平均温度的特征,并分析Bevis公式在中国的适用性。同时利用北京站2005-2010年的无线电探空数据进行北京地区加权平均温度模型的本地化研究,并利用模型进行北京地区2011年加权平均温度的计算,其结果与实际加权平均温度的差值平均值为2.16K,均方根误差为4.78,同时将利用模型生成的可降水汽量与利用探空数据获得的可降水汽量进行对比,差值平均值为-1.42K,均方根误差为2.87。实验证实北京地区本地化模型的精度较高,实用性较强。     

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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