承压完整井非稳定流抽水试验的观测时间要求

文章针对无界承压含水层中完整井的非稳定流抽水试验,将Theis公式描述的水位降深与时间的变化关系作为观测井外水位变化的理论真值,考虑观测井内外达到水力平衡所引起的滞后时间因素,推导了观测井内水位变化的理论测量值,分析了测量值与真值之间的相对误差以及测量值接近真值所需要的观测时间。     

傍河地下水位监测断面的优化设计

为了对傍河地下水位监测断面进行优化设计,更好地掌握地下水位动态时空变化特征,以安徽省亳州市河水-地下水监测断面为例,分别采用克里金法和时间序列法,通过分析监测断面上9口地下水位观测井及河水位观测点在1982年1月—1998年12月的水位观测数据,对观测井空间布局、井数和观测频率进行优化。结果表明：空间布局优化后的观测井数量由原来的9减少到3,平均相邻井距为1 000 m,优化后的水位克里金估计标准误差平均值为0.019 2 m,误差波动范围较小;观测频率优化后由5日一测变为10日一测,能够满足观测精度要求。     

乌鲁木齐台钻孔应变与水位相关性的初步研究

本文利用乌鲁木齐台钻孔应变观测井的水位突然变化求取了应变与水位的相关系数和回归系数,研究了水位与应变的关系以及利用此关系排除水位对观测值的影响,并作了简单的应用。     

易门井数字化水位水温同震响应及其机理探讨

研究了易门地震前兆观测井数字化水位水温观测资料对2004年12月26日印尼8.7级、2008年5月12日汶川8.0级和2011年3月11日日本9.0级大震同震响应特征,探讨其同震响应机理,给出水位水温同震响应的合理解释。表明易门井水位水温同震变化总是水位震荡下降—迅速恢复、水温迅速下降—缓慢恢复,形态相似。与观测井所在的地质构造、井深以及探头深度密切相关。     

台兰河地下水库辐射井抽水过程的非稳定渗流场的有限元分析

针对台兰河地下水库大口径辐射井抽水效果的数值模拟问题,在分析了大口径辐射井渗流行为基础上,提出了应用辐射井子结构法和子结构开关器等辐射井精细模拟技术,并联用改进的截止负压法、迭代增量法和求解大型稀疏矩阵的预处理共轭梯度算法进行有辐射井影响的地下水非稳定渗流场的有限元分析。应用自主研发的三维可视化渗流有限元计算软件GWSS对台兰河地下水库辐射井抽水试验过程中的非稳定渗流场进行了数值模拟研究。研究结果表明：所有观测井计算水位的平均绝对误差为0.22 m,单井水位的平均误差最大值为 0.40 m,最小值为0.02 m,各观测井地下水位的模拟值与实测值的变化趋势吻合较好。经验证算法的合理性和程序的可靠性较好。提出的辐射井子结构法可以精细模拟辐射井的渗流行为和局部精细渗流场,可用于分析辐射井抽水过程中的地下水非稳定渗流变化及取水效率评价。     

华北东部平原深层抽水井水跃值计算方法及其规律研究

文章分析了目前常用的几种水跃值计算方法的适用性与不足,认为在华北东部平原地下水位变化强烈的漏斗区,这些方法均难以应用。同时提出了C—G法,即一次定流量抽水同步观测抽水井和观测井的水位,合理地解决了区域背景水位对水跃值计算的影响。研究表明,与修正后的多次定流量试验法——两次定流量抽水法相比,C—G法计算结果可靠。然后探讨了如何间接获取抽水期间抽水层区域背景水位动态资料的方法,校正背景水位波动对抽水水位的影响,采用自动水位计(DIVER)同步监测井中大气压对地下水位的影响。最后分析水跃值随时间和抽水井水位降深的变化规律。     

北票渗滤取水工程井水位、水温动态特征

为研究渗流井取水条件下井水位和水温的动态变化特征,采用Mini-Diver小型地下水自动监测仪对北票渗滤取水工程抽水井进行超过一个水文年的长期观测,通过25 min一次的监测结果分析井水位和温度长期和短期的变化特征.结果表明:(1)井水位一个水文年内变化具有双峰特征,第一个峰值由融雪水补给引起,第二次水位峰值由降水引起...     

大厚度粗颗粒含水层井损值的确定

依据实际勘探资料,深刻分析了大厚度粗粒含水层井损值的影响因素。认为井损值主要受抽水井井壁管降深和井的最大出水量两个因素的影响和控制,三者之间高度相关,并建立了回归方程,井损值计算结果与实际观测值基本一致,应用效果较为理想。而采用现成的理论方法计算的井损值,由于其加坡系数在野外的不确定性,计算结果与实测观测值往往有着较大的差别。     

三维地下水流中常规观测孔水位的形成机理及确定方法

对地下水三维流中常规观测孔中水位的传统计算方法提出质疑, 认为计算观测孔中水位的Hantush Бочевер方程是缺乏物理基础的纯数学方法.分析了形成观测孔中水位的机理, 提出三维地下水流中常规观测孔中只是孔口的流量为零, 而孔内却存在"抽水"和"注水"的井孔; 多层井(multilayerwell) 不一定要求"多层"的条件, 在均质单一含水层中的井孔可以具有多层井的基本特征; 混合井孔的水位并不"混合", 混合观测孔中存在符合机理的水头分布和流量分布规律等观点.普遍而言, 三维流中的观测孔不能用通常所说的线汇/线源刻画, 也不能用近几年提出的孔内为层流(线性流) 的假定来研究该问题, 然而可用笔者于1993年提出的"渗流-管流耦合模型"和"等效渗透系数"方便、有效地模拟.就说明性算例而言, Hantush Бочевер方程只能近似用于孔径大于0.2m且径距大于10~20m的条件.      

断裂两盘井水位同震响应特征对比分析——以北京八宝山断裂带中段大灰厂两观测井为例

地震常引起分布于断层两盘观测井的水位同震响应动态变化特征不同。而研究断裂两盘观测井同震响应能力、水位变化特征的差异性及其控制因素,有助于揭示断裂带的渗透性演化过程、可深化地下水位对地震响应机理的认识,对于指导地震观测井网布局具有重要意义。本文尝试从北京八宝山断裂带中段（大灰厂）上下两盘井的水位同震响应次数、形态、幅度、记震能力等方面进行对比分析,通过去除趋势项,采用数字滤波求取井孔气压系数,采用Baytap-G程序求取潮汐参数,并反演出7次大地震对大灰厂区两口井所在含水层产生的体应变量,进而判别两盘震前震后渗透性的变化。结果显示,两口井同震响应特征具有明显差异,上盘井对大震的同震响应次数较多、能力较强;这不仅与断裂带起屏蔽作用有关,而且与井所处含水层渗透性呈不同规律变化密切相关。     

Spinel inclusions in olivine and plagioclase crystals in a layered gabbro: a marker and a tracer for primary phenocrysts in a differentiating magma reservoir

The problem of whether cumulate rocks were formed by crystal settling or by in situ crystallization after magma emplacement is an important issue concerning the mechanisms of magmatic differentiation. However, it is hard to distinguish these two processes for plutonic rocks because the primary texture and chemical composition have generally been modified by postcumulus processes. To contribute this problem, we studied the distribution and compositions of Cr-spinel inclusions hosted in olivine and plagioclase in the Murotomisaki Gabbroic Intrusion (MGI), SW Japan. It is shown that the olivine-hosted inclusions are restricted to specific horizons where accumulation of olivine phenocrysts is thought to have occurred and that the compositional variations of the Cr-spinel are explained by a secondary compositional modification that probably took place after the magma emplacement. It is also shown that the Cr-spinel inclusions in a chilled margin have suffered the least compositional modification and nearly retains the primary composition. Those in the interior of the intrusion, on the contrary, have been significantly modified by re-equilibration with residual melt driven by cation diffusions through the host phases. Those in plagioclase have been less modified. It is shown that all the spinel inclusions had primarily the same and common composition at the time of magma emplacement. This implies that all the inclusion-bearing crystals, olivine and plagioclase, represent primary phenocrysts that had already existed in the emplaced magma. In this way, spinel inclusion in the MGI may be regarded to be a useful petrographic “marker” for identifying intratelluric phenocrysts and also as a “tracer” to trace the motion of the primary phenocrysts after the magma emplacement.     

Sources of Salinity Variation in a Coastal Lagoon in a Karst Landscape

Bahia de la Ascension (BA) is a shallow, mangrove-fringed coastal bay connected to the Caribbean through two inlets, outlined by the Mesoamerican Barrier Reef System. This work represents an initial investigation of the relative contribution of hydrometeorological and hydrodynamic forcing on salinity variation in this lagoon. Our objective is to assess the sensitivity of the salinity in BA to fluctuations in freshwater inflow and coastal oceanography. Two field trips were undertaken during rainy and dry seasons in 2007. Surface salinity was mapped across the system and CTD deployments carried out within BA and in the sea end-member to characterize temperature, conductivity, and water level. Also, cross-sectional CTD profiles were implemented to examine vertical stratification. The water balance indicated that 16 % of rainfall over the drainage basin (DB) becomes groundwater discharge plus surface runoff into BA during dry season, while 68 % of the precipitation input to the DB is supplied through groundwater–surface runoff to the bay during rainfalls. This combined inflow showed larger fluctuations than direct rainfall and, thus, has a greater potential to alter the seasonal salinity variations within BA. The tidal signal is selectively attenuated within BA, as diurnal frequencies are more readily filtered out than semidiurnal frequencies. Mesohaline conditions in the southwest bay are associated with freshwater sources, while saline water masses in the inlet are influenced by prevalent SE winds in the region and tidal phase, establishing a strong horizontal SW-NE estuarine salinity gradient.     

翼龙重建：方法论的一个研究例子

Reconstructions of fossil animals are widespread and often very high profile, yet many of these reconstructions exhibit low standards of scientific accuracy.     

Spreading of a NAPL lens in a double-porosity medium

Spreading of a non-aqueous phase liquid (NAPL) denser than water (DNAPL) lens (mound) in the unsaturated zone of double-porosity aquifer above an impervious plane boundary is investigated. The double-porosity aquifer is conceptualized as a fracture network surrounding pervious blocks. Vertical gravity equilibrium is assumed to prevail in each one of the two media, fractures and blocks. Through vertical integration, two coupled partial differential equations for the DNAPL content in each medium are obtained. The mass exchange rate between high- and low-permeability media is considered as a function of NAPL content. The dominant effect is gravity, whereas capillary forces are negligible. Analytical solutions for one-dimensional and axisymmetric problems of mound spreading are obtained.     

Toward a definition of a mineral sample in geology

Summary Any rock may be regarded as an aggregate of mineral species frequency distributions, thus opening up a new method of analyzing the problems of the nature of these discrete distributions.Based on theorems in mathematical probability, a subrock sample is defined as a probability sample under the conditions that every mineral species' distribution function in this subrock converges probabilistically to one and the same distributions the nature of which is immaterial at this point.For obvious reasons, the situation is excluded if the sample size approaches infinity, i.e., Chebyshev's theorem (Chebyshev, 1867).     

Paleostress determination in a rock by a fractographic method

A fractographic technique, hitherto used in ceramics for the evaluation of fracture stress, is adapted here to calculate fracture paleostresses in rocks. An example from a granite in East Sinai is analyzed. The results obtained for the ranges of local paleofracture stress, the severest flaw size and the initial stress intensity factor agree reasonably well with previous evaluations of fracture stresses in granite and with direct observations of the rock's grain size.     

Propagation of a shear crack in a compressed plane with a circular hole

The problem of the equilibrium of a plane with a circular hole and a shear crack is considered to model failure of an excavation (borehole or circular opening) in rocks weakened by discontinuities (planes of weakness). It is assumed that sliding occurs in a part of the plane of weakness when the Mohr–Coulomb friction criterion is satisfied due to the stress redistribution caused by the excavation. The method of singular integral equations is employed to solve the boundary value problem. Geomechanical problems concerning borehole breakout and rockburst caused by fault-opening interaction are discussed. © 1998 John Wiley & Sons, Ltd.     

Fracture in a heterogeneous medium: a network approach

Fracture in a heterogeneous medium is simulated by a network model. Heterogeneity is introduced by randomly distributing an initial population of cracks on a triangular network of bonds. Each ruptured bond represents a crack. External stresses are applied onto the network and the evolution of the crack population is analysed when the stresses are increased. A crack will propagate to an intact bond if the critical crack extension force is reached. This propagation leads to the coalescence of bonds: crack clusters are formed. When their shapes are complex we approximate them by simpler ones to compute a crack extension force. Crack interactions are introduced by adding for a given bond the contributions of all adjacent dusters. By using this kind of approach combining fracture mechanics and network modelling, we are able to simulate the rupture of a rock specimen under compression/ traction or shear stresses and to give some characteristics of the macroscopic fracture.     

Strain analysis of a shear zone in a granodiorite

A ductile shear zone in a late Precambrian granodiorite, from the Rouergue (southwest part of the French Massif Central) has been studied.A single episode of deformation is responsible for the formation of a foliation and a well-defined lineation which are localized into an elongated zone, a few decimeters wide.The strain features can be attributed to a simple-shear mechanism (Ramsay and Graham, 1970), so that the main parameters of the deformation are defined.At stages of increasing deformation, the quartz isotropic sub-fabric of the undeformed host rock is progressively transformed into an anisotropic fabric composed of a single oblique girdle while the subgrain size progressively decrease and the dislocation density remains constant. It is suggested that the gliding planes of quartz are the basal plane (0001) and a predominant prismatic plane 101̄0 the slip directions may be a for both glide-planes.The results obtained in this investigation provide a basis for a high voltage electron microscope (H.V.E.M.) study which shows that the fabrics development may be related to dislocation processes. The difference of strain rates in the host rock and in the shear zone is calculated from the dislocation microstructures.