强导(含)水隐伏陷落柱底板突水机理研究

华北型煤田采场底板隐伏强导(含)水岩溶陷落柱突水以其隐蔽性强,突水速度快,水量大,破坏性强,危害严重的特点已成为影响煤矿安全生产的重大隐患.但是,受奥陶系灰岩承压水和采动应力耦合作用下的岩溶陷落柱突水机理、突水过程和突水力学规律的研究尚不够系统和完善.本文以陷落柱上覆岩层层状介质假设和剪切破坏理论方法为出发点,建立了不同水平截面形状类型的强导(含)水岩溶陷落柱突水力学模型,并确立了奥灰承压水与采动应力共同作用诱发强导(含)水陷落柱突水的临界条件,并提出了突水危险性系数对陷落柱突水危险性进行定性和定量的评价.理论推导和数值分析表明,奥灰承压水和采动应力耦合作用下的强导(含)水陷落柱突水与其水平截面形状、隔水层厚度、岩石物理性质有关.当采场环境确定后,陷落柱水平截面形状则是决定其突水的关键因素,而且陷落柱水平截面形状是圆形时最容易发生突水.     

腾冲地震台数字化水温观测数据异常分析

腾冲地震台数字化水温记录多次出现数据突跳,影响观测资料质量。引入1套相同型号的水温仪进行对比观测,对可能引起原水温仪数据突跳的因素(静电干扰、供电电压、仪器探头故障等)进行一一排查,结果表明,水温仪主机数据转换模块工作不正常是引起水温数据突跳、阶变的主要原因,仪器供电电压不稳、雷电因素对数据突跳的产生有促进作用。消除水温数据突跳干扰的有效解决办法是更换1套水温观测仪器。     

数字化体应变仪观测值突跳的分析

山东长清台数字化体应变仪观测曲线自1999年以来出现几次形态类似的大幅度突跳,为正确认识这类现象,在长清台做了交直流切换对观测值影响试验,并对水位、气压资料进行综合分析。研究结果表明,水位、气压、电源切换等因素不会引起体应变仪观测曲线的突跳。对比其他类似观测分析推测,这类突跳可能与“慢地震”事件或“岩孔崩落”现象有关。     

深水钻探面临的挑战:浅水流灾害问题

浅水流(shallow water flow,简称SWF)灾害被看作深水钻探中面临的重要挑战之一,它是指深水钻探中,钻头钻过一超压砂层时,孔隙压力太大以致砂和水激烈流进到井眼里,导致了井和钻井平台损坏的事件.SWF问题仅发生在深水区,位于海底泥线下几百米以下,主要出现在一种原位超压的未固结的斜状砂体中,这种砂体一般被低渗透的泥覆盖.超压的形成常认为是快速沉积压实所致,也可能与构造因素或水合物分解有关.SWF砂体具有低密度、低速度和高Vp/Vs的性质,是可能被地震勘探方法所检测的.我国即将进入深水钻探领域,为了避免或减轻深水钻探中可能面对的SWF灾害,我们建议开展有关SWF灾害问题的前期研究.     

头颈部CTA对茎突解剖的应用研究

目的:运用头颈部CTA对茎突的解剖进行研究。资料与方法:随机选取我院200例进行头颈部CTA检查的受试者,年龄范围21~82岁,平均年龄(57.38±9.99)岁。根据受试者年龄进行分组,A组<60岁,B组≥60岁。将原始数据传入GE AW 4.5工作站进行容积再现(VR),多平面重组(MPR)等后处理,观察颞骨茎突的形态,并分型;测量茎突的长度、内倾角、前倾角及茎突尖端与颈内外动脉之间的最短距离。结果:197例受试者茎突平均长度约为26.79 mm,内倾角约为21.07°,前倾角约为25.03°,茎突尖端与颈内动脉最短距离均值约为6.26 mm,与颈外动脉最短距离均值约为4.15 mm;茎突尖端与颈外动脉最短距离为0的有44个,占总数的11.2%。双侧茎突长度、内倾角、茎突尖端与颈外动脉最短距离及右侧前倾角性别差异具有统计学意义(P<0.05);内倾角、茎突尖端与颈外动脉最短距离左右侧差异具有统计学意义(P<0.05)。茎突分为4型,各型的比例分别为:完整型(71.75%),发育不良型(22.75%),分节型(4.25%)及未发育型(1.25%)。结论:头颈部CTA不仅能显示茎突的形态、测量茎突的长度、内倾角及前倾角,更能清晰显示茎突与颈内外动脉之间的关系,测量茎突尖端与动脉之间的最短距离,对临床诊断及治疗茎突相关疾病有一定指导及参考意义。      

固体潮与矿井坍崩事故

矿井是人类的重要资源和环境。从矿井内的宏观前兆、象力理论和引潮力的影响讨论了矿井灾害的预测问题。     

突变理论在地震资料解释异常地质体中的应用

阐述了尖点突变理论,建立了地震信号尖点突变模型并转化为尖点突变的标准形式,在时间域内提取突跳势、突跳时间;在频率域内提取突跳势、突跳次数等参数.运用突变理论对实际地震资料进行薄煤带的解释表明:突跳参数曲线上异常的位置与异常地质体边界的位置有关,为地震资料解释异常地质体提供了一种新的途径.     

四川省宣汉县炉厂坪井田炉坪煤矿充水因素分析

炉坪煤矿矿井涌水量主要受大气降水影响较大,同时井下涌水量还随煤层开采面积的扩大和开采深度的增加而增加。炉坪煤矿矿井主要充水因素有大气降水、直接裂隙充水含水层水、采空区积水、断层水及老窑积水,其中尤以浅部老窑及老采空区积水的渗漏补给量突然溃入矿井危害最大。     

地下核磁共振小尺寸线圈设计和实验

很多国家在进行隧道挖掘、地下矿体开采时,经常会遇到突水涌泥事故.核磁共振方法(Magnetic Resonance Sounding,MRS)作为目前唯一一种直接找水的地球物理技术,在探测诱发灾害的水体方面具有明显的优势.本文首先给出了多匝分离式线圈的MRS信号响应和核函数的计算公式,分析了线圈的匝数、边长和含水层位置对MRS信号响应的影响.分析表明,在限定空间内,利用多匝分离式线圈的设计方法可以提高小尺寸线圈的探测能力.同时,对高匝数线圈给探测系统带来的不利因素进行了分析和改进.最后,为了验证本研究所采用的方法,利用6 m边长的方形线圈和改进型MRS探测系统在中国温州一处在建隧道内的地下场地进行实地探测,探测结果与瞬变电磁方法结果对比表明,6 m边长的方形线圈可以对地下30 m内的含水层进行有效探测.     

渗流作用下岩溶陷落柱侧壁突水的临界水压解析解

在陷落柱侧壁突水研究中引入厚壁筒力学模型,将陷落柱侧壁煤柱视为多孔介质,考虑地下水的渗流体积力,应用摩尔库伦强度理论和弹塑性力学模型,推导出煤柱弹塑性状态应力解析式,以及煤柱内塑性区半径与水压力的关系表达式,同时编程试算出陷落柱侧壁突水的临界水压力。在此基础上,分析了煤柱孔隙率、煤柱抗剪强度参数以及煤柱宽度等因素对陷落柱侧壁突水的临界水压力的影响规律。研究结果表明：1煤柱能够承受的临界水压随着煤柱孔隙率的增加而降低,故当煤柱裂隙发育时,不考虑渗流力的结果将偏于安全;2煤柱宽度越大、抗剪强度越高,则临界水压越大,陷落柱侧壁突水的危险性越低;3可通过注入水泥浆液减小煤柱孔隙率和提高煤柱强度来防止陷落柱侧壁突水,同时可减少煤柱的留设宽度,对减少煤炭损失有着重要意义。     

基于渗流-应力耦合分析的野鸡尾尾矿坝稳定性研究

基于渗流场与应力场耦合机理,对柿竹园野鸡尾尾矿坝进行稳定性研究。研究渗流-应力的耦合效应,提出了渗流-应力耦合以及渗流体积力计算的实施方案;建立二维的有限元渗流-应力耦合计算模型,分析了考虑耦合效应时的尾矿坝渗流场、位移场、应力场;最终分析了不同耦合关系对于渗流量、位移场、等效渗透集中力以及应力场的影响。研究结果表明：当前水力条件下,尾矿坝稳定性良好;尾矿坝主要受水平渗透力作用,初期坝坝顶、坝脚以及坝底等处应力集中;尾矿坝的渗流-应力作用不容忽视,不同的耦合关系对于x方向位移、渗透力的预测影响巨大;考虑渗流-应力耦合关系得到的主应力、剪应力以及竖向位移,比不考虑耦合效应时大。     

软弱结构面水流冲刷形成集中渗漏通道机制研究

软弱结构面塑性程度高、强度低,在地下水长期作用下,很易导致岩体产生变形、形成集中渗漏通道及渗透破坏。软弱结构面的渗透稳定性,一直是水利水电工程的重要工程地质及水文地质问题之一,目前对其渗透破坏机理的认识还存在不少尚未解决的问题。针对已有对基岩软弱结构形成集中渗漏通道研究的不足,本文在软弱结构面内讨论渗透变形问题,主要探讨了软弱结构面受水流冲刷发展的机制,以及土粒起动处于不同位置时的临界流速及相应隙宽。最后介绍了在适当地质等条件下,基岩软弱结构面可形成集中渗漏通道的实例。     

STABILITY ANALYSIS OF RIVERBANK SUBJECT TO SEEPAGE

The stability of riverbanks subject to seepage is studied experimentally and theoretically in this paper. By including seepage in a 3-dimensional theoretical analysis, the study first shows how the critical slope or angle of repose of a cohesionless material is related to the ratio of the hydraulic gradient of seepage to its critical value under the fluidization condition. The critical stable slope is shown to be related to not only the hydraulic gradient but also the seepage direction. Measured laboratory data reasonably fit well with the theoretical relationship for the case of injection and suction. The data reveal that the slope is reduced with injection and increased with suction, respectively. Additionally, the study identifies the seepage direction which results in a minimum critical stable slope for a certain hydraulic gradient of seepage.     

应力调整改变介质渗透性对水位的影响

在岩石抽水-注水试验的基础上,通过应力和渗透系数的关系,用数值模拟的方法讨论了应力与渗流的过程。研究结果表明,随着应力场的调整介质的渗透性将发生改变,从而对渗流过程产生影响,这种影响是非线性的,渗流作用的存在使得水位的变化与介质的渗透性的变化不是对应的关系。     

The distribution rule and seepage effect of the fractures in the ultra-low permeability sandstone reservoir in east Gansu Province,Ordos Basin

To study the impact of the fractures on development in the ultra-low permeability sandstone reservoir of the Yangchang Formation of the Upper Triassic in the Ordos Basin,data on outcrops,cores,slices,well logging and experiments are utilized to analyze the cause of the formation of the fractures,their distribution rules and the control factors and discuss the seepage flow effect of the fractures. In the studied area developed chiefly high-angle tectonic fractures and horizontal bedding fractures,inter-granular fractures and grain boundary fractures as well. Grain boundary fractures and intragranular fractures serve as vital channels linking intragranular pores and intergranular solution pores in the reservoir matrix,thus providing a good connectivity between the pores in the ultra-low perme-ability sandstone reservoir. The formation of fractures and their distribution are influenced by such external and internal factors as the palaeo-tectonic stress field,the reservoir lithological character,the thickness of the rock layer and the anisotropy of a layer. The present-day stress field influences the preservative state of fractures and their seepage flow effect. Under the tec-tonic effect of both the Yanshan and Himalayan periods,in this region four sets of fractures are distributed,respectively assuming the NE-SW,NW-SE,nearly E-W and nearly S-N orientations,but,due to the effect of the rock anisotropy of the rock formation,in some part of it two groups of nearly orthogonal fractures are chiefly distributed. Under the effect of the present-day stress field,the fractures that assume the NE-SW direction have a good connectivity,big apertures,a high permeability and a minimum starting pressure,all of which are main advantages of the seepage fractures in this region. With the development of oilfields,the permeability of the fractures of dif-ferent directions will have a dynamic change.     

上游型尾矿坝液化前后渗流场与孔压分布数值模拟

针对地震(或静力)液化作用对尾矿坝渗流场和孔压分布的影响进行研究,基于多孔介质渗流理论,考虑到尾矿坝渗流特性,编写分析程序SAFTD。根据程序假设的初始浸润面,通过调整浸润面处网格迭代求解最终浸润面的位置,选取一个经典算例验证程序的可靠性。针对典型的上游法尾矿库,采用SAFTD程序分析液化前后尾矿坝的渗流场与孔压分布特征。数值模拟结果表明,液化后尾矿坝的浸润面中间部分发生明显抬升,而在入渗点处和出渗点附近变化不大;液化后尾矿坝的孔压明显增加,坝体内部孔压增大约18%~280%,最大的孔压增量发生在初期坝的右下部,数值模拟结果与Ishihara对Mochikoshi 2号坝的分析结果相似。     

Seepage driving effect on deformations of San Fernando dams

In the process of flow deformation of an earth dam, the seepage force inside the dam plays a role as a driving force. The seepage force acts just like the gravitational force in terms of pushing soils away from their original locations after liquefaction is triggered. This paper draws attention to this seepage driving effect by presenting a set of fully coupled finite element analyses on the well-known San Fernando dams, with the objective of evaluating the impact of this seepage effect. The results indicate that while this effect is always there, its practical significance depends on a number of factors. In the case of the upper San Fernando dam, which experienced a significant, but restricted, downstream movement during the 1971 earthquake, the seepage driving effect was indeed significant. On the contrary, for the lower dam, which failed and slid into the upstream reservoir during the same earthquake, this seepage effect was relatively less pronounced. The detailed results of the analyses reveal the likely mechanisms of failure and deformation of the two dams and the likely cause behind the difference between their responses during the earthquake.     

Subsurface flow from a forested slope in the Ife area of southwestern Nigeria

ABSTRACT

Lateral subsurface flow within a 10% forested slope in a part of the humid tropics of southwestern Nigeria during 1982 is described with particular regard to the cumulative amount, timing and frequency of seepage, the relative contributions of the various soil horizons to the total seepage, and factors affecting these seepage parameters. Seepage was collected at 30, 500, 900, 1200 and 1800 mm depths by means of troughs connected to plastic collectors, and measurements were made between March and November 1982. The total amount of seepage during the study year was 67.7 mm and this was obtained from a total of 29 seepage days. This is considered low given the number of rainy days (106), the total rainfall for this period (924 mm) and results from other environments. The impeding layer in the soil is within the 900–1200 mm horizon, but the largest relative contribution to total seepage was not from the horizon immediately above this layer (i.e. 500–900 mm), but from the surface 0–30 mm horizon. Soil moisture status and hydraulic conductivity as influenced by the rainfall pattern were found to be very important in controlling the seepage patterns.     

Geophysical and Hydrologic Studies of Lake Seepage Variability

Variations in lake seepage were studied along a 130 m shoreline of Mirror Lake NH. Seepage was downward from the lake to groundwater; rates measured from 28 seepage meters varied from 0 to ?282 cm/d. Causes of this variation were investigated using electrical resistivity surveys and lakebed sediment characterization. Two‐dimensional (2D) resistivity surveys showed a transition in lakebed sediments from outwash to till that correlated with high‐ and low‐seepage zones, respectively. However, the 2D survey was not able to predict smaller scale variations within these facies. In the outwash, fast seepage was associated with permeability variations in a thin (2 cm) layer of sediments at the top of the lakebed. In the till, where seepage was slower than that in the outwash, a three‐dimensional resistivity survey mapped a point of high seepage associated with heterogeneity (lower resistivity and likely higher permeability). Points of focused flow across the sediment–water interface are difficult to detect and can transmit a large percentage of total exchange. Using a series of electrical resistivity geophysical methods in combination with hydrologic data to locate heterogeneities that affect seepage rates can help guide seepage meter placement. Improving our understanding of the causes and types of heterogeneity in lake seepage will provide better data for lake budgets and prediction of mass transfer of solutes or contaminants between lakes and groundwater.