用稳定流方法计算含水层渗透系数中几个问题的讨论

含水层渗透系数是评价地下水资源,拟定开采方案的主要参数之一。用裘布依涌水量方程求得的渗透系数一般偏小,实际是抽水井孔壁附近水位和井内水位之间存在着一个差值,即所谓的水跃值。裘布依在推导“方程”时没考虑水跃值。本文希望通过阐述水跃值的产生及其计算方法来证实水跃值对参数的影响,从而确定准确求参数的方法。     

福建漳州新城大厦基坑降水工程成井工艺实例分析

根据福建漳州新城大厦基坑降水井口径大、单井涌水量大的特点，采用了350 mm钢筋笼外包一层20目不锈钢丝网和一层28目尼龙网，孔隙率比钢管作滤管高3倍以上，增大了过水面积，降低了水跃值；管壁与孔壁间采用粒径比规范值大一级且大小不等(1～4 cm)的砾卵石作为滤料充填，洗井时间比按规范值填砾缩短2/3，井内泥浆采用排污泵排除，并与空压机清洗联用，洗井速度快，效果好。     

潜水井最大涌水量的计算

本文首先指出了潜水井最大涌水量与降深值的关系,目前未能得到很好解决的根本原因,进而根据流体运动能量变化的理论推导出新的(最大)涌水量与降深值的关系式,并计算出某些涌水量与降深值的关系曲线。     

井周流场对裘布依涌水量方程的影响

一个多世纪以来,裘布依涌水量方程方生产实践中得到了广泛的应用,但用“方程”求得之渗透系数往往偏小,且是一个与井内降深、观测孔距离有关的随机变量,与理论发生了矛盾。     

根据流体运动的能量变化计算单井稳定流抽水涌水量

在抽水过程中,如果已知某一降深地下水通过井壁周围岩层的孔隙和裂隙流入井内的速度V、过水断面W,可以求出这一降深的涌水量Q=WV。就如图1所示承压井而言,此承压井含水层厚度为M,井半径为v,水位降深为S,抽水前的稳定水位距含水层底板的距离为H_1,抽水后井内的水位距含水层的底板的距离为H_2,设含水断面的有效孔隙率为n_e(即多孔介质     

对单井抽水资料的处理及精度评价的讨论

本文阐述了井损的基本特征，着重讨论了单位涌水量、涌水量曲线方程及参数获取三个方面在实践中存在的问题、推举一种计算井损及校正降深的有效方法，并通过实例说明裘布依渗透系数与泰斯渗透系数间的理论相对误差关系同客观实际相吻合。由理论误差分析式结合实例进一步说明所推举的校正降深方法之理论的可靠性。     

孔隙潜水井水跃值影响因素及相关方程的探讨

在各类水文地质勘探试验中发现,各类不同设备抽水产生的水跃值各不相同。本文根据对比试验,取得了不同井的结构,不同抽水机械,不同水位降低值的水跃值资料,最后确定了相关方程公式,为地下水参数计算、评价提供依据。     

低孔渗储层井周油藏侵入模拟及阵列感应电阻率校正方法

泥浆滤液侵入渗透性地层会改变井周地层流体的原始分布状态,使井周地层电阻率发生变化、储集层电测井响应失真。本文基于油水两相渗流理论和水对流扩散理论,应用数值模拟方法构建地层模型,研究低渗储层泥浆侵入过程中井周地层矿化度、含水饱和度、电阻率变化特征及井周油藏分布特征。对不同渗透率地层泥浆侵入的数值模拟结果表明:在低渗透储层,相同侵入时间内,随着地层渗透率的增加,泥浆侵入深度增加,且同一侵入深度的含油饱和度减小;随着侵入时间的增加,井周地层水矿化度、含水饱和度和地层电阻率的侵入剖面前缘均发生明显的变化。结合3口井的泥浆侵入数值模拟分析,发现阵列感应测井响应特征及其电阻率的幅度差异受泥浆侵入时间和侵入深度影响。不同流体性质层段的井周油藏动态演化规律模拟结果表明,井周油藏的变化情况与储层流体性质有明显关系。利用实例井侵入模拟结果与阵列感应测井响应的相关性,构建了侵入深度的计算公式;根据侵入阶跃剖面,利用几何因子理论构建了原始地层电阻率计算公式,用以辅助储层电阻率校正。正确认识井周地层泥浆侵入特征及井周油藏的分布情况有助于提高阵列感应测井评价储层的准确性。     

淮南潘谢矿区各矿井基建井巷含水层涌水规律的研究

基建井巷分层涌水量的准确预测是目前存在的难点。在地质和水文地质条件玎类似的淮南潘谢矿区内，充分利用为数较多，分布面广的建井涌水实际资料，通过相关分析，发现井巷涌水量大小与含水层的埋藏深度、地质构造、含水层岩性柘者密切相关；同时使用了数学地质中的回归分析方法及涌水量的曲线方程法，计算出不同岩性砂岩含水层随埋深变化的涌水量回归方程和涌水曲线方程。     

井周钻孔补砾工艺在修井中的应用

提出了通过井周钻孔恢复旧井填砾层，提高管井涌水量的方法，通过在某电厂供水管井中的实践，证明效果良好。     

黄土潜水含水层深井抽水的井流特性分析

本文通过对黄土地区潜水含水层深井进行现场单井多落程抽水试验和双井抽水试验资料的整理分析,得到黄土潜水含水层深井抽水井流的一般规律,同时对水跃值的变化规律进行分析.     

垃圾填埋场抽水试验及降水方案设计

垃圾填埋场中的渗滤液水位过高会引发一系列环境和稳定问题,工程上可用竖井抽水降低渗滤液水位。通过在填埋场现场进行抽水试验,确定垃圾土的渗透系数和抽水影响半径,在此基础上对填埋场降水的瞬态流问题进行有限元模拟,分析了抽水井口径和间距对填埋场降水的影响,提出了降水方案的设计步骤和方法。抽水试验表明,现场垃圾的渗透系数约为3.6×10-4cm/s,抽水影响半径约为20m。数值分析表明,井径的变化对于降水效果影响不大,而合理选择抽水井间距对降水十分关键。进行抽水方案设计时,应首先根据工期和降水幅度要求计算井间距,按井的出水速度选择水泵,再根据水泵确定井径,最后根据井径和过滤层形式确定钻孔尺寸并选择钻机。     

A case history of field pumping tests in a deep gravel formation in the Taipei Basin,Taiwan

33 large-diameter wells embedded in 2-m thick, 63-m deep diaphragm walls were constructed to reduce both the uplift pressures and the groundwater inflow during the excavations. As the actual thickness of the pumped aquifer is unknown, the installed wells are regarded as partial penetration wells. Single-well and multi-well pumping tests were conducted in the deep gravel formation of Taipei Basin to derive the hydraulic parameters and to investigate the drawdown characteristics at both the construction and remote sites. However, the tidal effect on the drawdown of both the pumping well and nearby observation wells was found significant. Additionally, wellbore storage, skin, and leakage need to be taken into account for deriving the hydraulic parameters. Hence, a method to remove these five factors influencing the drawdown curve is developed, which takes advantage from the late-time characteristics of drawdown data and the early-time behavior of drawdown. Some currently available semi-log graphic techniques are therefore proven applicable for parameter determination. Validity of the proposed method is verified by the good agreement between the calculated and the measured drawdown of both the pumping well and observation well.     

稳定井流直线图解法确定含水层参数

对于潜水井流,利用Dupuit公式计算的参数往往相差很大,难以直接选用。对Dupuit公式进行线性化,建立降深(s)与距离(r)的s-lnr直线关系,利用直线斜率、直线在x轴上的截距,可以直接求得唯一的渗透系数K和影响半径R。利用松花江河谷的承压水井抽水试验资料和洮儿河扇形地27个潜水抽水井及其观测孔的抽水试验资料,应用直线图解法分析计算,得到唯一的含水层参数T、K和R。将计算结果与直接利用Dupuit公式所计算的结果相比较,前者的求参效果较好。     

Parameters affecting the occurrence of quicksand and the drying up of large diameter wells that gain water from the bottom: a case study from Iran

Large diameter fully cased wells that gain water from the bottom are often dug in sandy and collapsible aquifers. They have cylindrical vertical walls lined with brick or concrete. The well bottom is partially filled with aquifer material through which the flow is vertically upward. When the vertical hydraulic gradient reaches a critical value, quicksand occurs and the well structure can be destroyed. Another difficulty encountered is drawdown in the wellbore and the drying up of the well. To overcome these problems, the flow around and beneath these wells is numerically simulated. The simulation results are used to investigate the effect of well and aquifer parameters on quicksand and drawdown. For practical purposes, the dimensionless drawdown-time and dimensionless vertical gradient-time curves are developed. It was found that the ratio of filling material thickness to well radius affects the shape of these type curves. The type curves may be used to predict the time after pumping commences when quicksand occurs and the well dries up. They are also useful to design the safe pumping rate and duration as well as the optimum well radius. These are demonstrated by analyzing the pumping test data from a case study in the arid Chah Kutah region, southern Iran.     

沈阳市阳光港湾建筑群基坑降水施工研究

沈阳市阳光港湾建筑群高层建筑采用筏板基础,多层建筑采用人工挖孔灌注桩基础,在基础施工时,均需进行相应的降水工作。采用了分期降水的施工方法,首期降水施工是在分析场地水文地质条件的基础上,利用稳定流"大井法"预算基坑的涌水量,布置了9口井,使基坑周边的1#、2#、3#、4#观测孔水位均下降至5.11m,基本上达到了首期的降水的目的;第二期降水是利用首期降水观测的水位资料,采用稳定流干扰井群计算公式对场区地下水位进行了预报,重新设计了3口井。12口井全部投放使用后,测得稳定排水量为43 000m3/d,并形成了以基坑为中心的地下水降落漏斗,降水效果明显。此经验值得同类工程借鉴。     

Detecting transmissive bedrock fracture zones under cover of glacial formations using residential water-well production data

Tracing fractures under glacial drift commonly involves costly and often unfeasible (in populated areas) geophysical methods or outcrop surveys, often far from the area of interest. A hypothesis is tested, that the specific capacity data for wells penetrating through glacial drift into a bedrock aquifer display two statistical populations: assuming uniform well construction, the wells with high specific capacity penetrate transmissive fracture zones, while those with low specific capacity encounter non-fractured rock characterized by primary porosity. The hypothesis was tested on 617 wells drilled into the Pennsylvanian Sharon Sandstone, Geauga County, Ohio (USA). Hydraulic conductivity, calculated using the Cooper and Jacob (1946) approximation to Theis’ non-equilibrium radial flow equation, followed quasi-log-normal distribution (geometric mean 9.88?×?10^?6 m/s). The lower values presumably correspond to primary porosity, and higher values correspond to bedrock fracture zones. The higher hydraulic conductivity followed two distinct orientations (N34°E, N44°W), corresponding with the regional fracture pattern of the Allegheny Plateau. A variogram showed that the wells within a kilometer of each other correlate and that wells penetrating the thicker glacial blanket have lower hydraulic conductivity and larger drawdown. Cooper and Jacob (1946) A generalized graphical method for evaluating formation constants and summarizing well-field history, Am. Geoph. Union Trans. 27/4:526–534.     

渐扩散水跃跃长的研究

首先通过对作用于渐扩散水跃的压力分析,阐述了渐扩散水跃跃长总比非扩散水跃跃长短的原理。在此理论基础上,考虑边墙扩散角的影响,建立了渐扩散水跃表面质点运动方程,并结合动量方程和连续方程,推导出渐扩散水跃跃长的半理论、半经验公式。同时,引入非扩散水跃跃长经验公式,使渐扩散水跃跃长公式大大简化。其次,对该理论的局限性进行了分析,得到了该公式的适用范围。在该范围内,该公式能较好地吻合实验结果,从而该理论得以证实。最后对各家渐扩散水跃跃长经验公式进行分析归类,并推荐工程适用公式,以便工程运用。     

地下水位变化对透—阻型岩溶塌陷影响的分析

文章从一维地下水运动和渗透力学的角度,分析比较潜水位上升与承压水位下降对岩溶地区透—阻型盖层中阻水层渗透稳定性的影响,重点讨论了承压水位下降速度(降速)与下降深度（降深）对阻水层中渗透坡降的影响,结果表明:地下水位变化（潜水位上升或承压水位下降）产生的非稳定渗流不利于岩溶洞穴开口上方阻水层的稳定,承压水位的下降对岩溶开口附近处阻水层中渗透力的影响远大于潜水位的变化;在承压层水位最大降深确定的条件下,承压水位下降速度愈快,岩溶开口附近处阻水层中向下渗透力愈大。因此,在覆盖型岩溶地区抽取地下水时,为了减缓或避免覆盖型塌陷的发生,应同时控制好最大降深和最大开采速度。      

How appropriate is the Thiem equation for describing groundwater flow to actual wells?

The Thiem equation of radial groundwater flow to a well is more than 100 years old and is still commonly used. Here, deviations caused by some of its simplifications are quantified by comparing the analytical to a numerical model that allows the implementation of more complex geometries. The assumption of horizontal flow in the Thiem equation, which necessitates uniform inflow over the entire screen length of the fully penetrating well, was found to cause deviations from actual pumping wells where the pump is placed above the screen, resulting in non-uniform inflow and additional drawdown. The same applies to partially penetrating wells, where inflow peaks and additional drawdown occur, especially when the well is screened in the lower part of the aquifer. The use of the Thiem equation in the near-field of a well should thus be restricted to situations where the screen inflow is relatively uniformly distributed, e.g. when it covers large portions of the aquifer thickness. The presence of a gravel pack and a background gradient, on the other hand, are of limited importance.