滹滏平原地下水系统脆弱性最佳地下水水位埋深探讨

笔者以滹滏平原为研究区, 采用统计分析的方法, 分析了地下水防污性与地下水资源脆弱性随地下水位埋深之间的变化关系。结果表明, 当地下水位埋深增大时, 地下水防污性增强的地区, 地下水资源脆弱性也增高;通过二者之间变化关系, 认为受地下水位埋深制约及地下水位埋深对二者的不同影响, 存在使地下水系统脆弱性最佳的地下水位埋深区间;通过地下水位埋深对地下水防污性与地下水资源脆弱性影响及其制约关系, 确定滹滏平原淡水区和咸水区地下水系统脆弱性最佳地下水位埋深分别为27~30 m和15~19 m。     

隧道含水构造直流电阻率法超前探测研究

含导水构造和岩溶裂隙水的探查是亟需研究和解决的关键问题。直流电阻率法以其对低阻体反映敏感、分辨率高等优点被引入到隧道掌子面前方含水构造的预报工作中。首先,推导出了无限全空间中球体含水构造直流电法超前探测的解析解公式,并在利用有限元数值方法进行正演分析的基础上,借助“比较法”将含隧道腔体的三维空间中超前探测视电阻率数据转换为无限全空间中的数据,并探讨了由MN电极附近电阻率不均匀所造成的干扰以及识别和去除这种干扰的方法。然后,设计了基于全空间球体含水构造超前探测解析公式的阻尼最小二乘反演方法,对隧道中多组球体含水构造模型进行了较为成功的反演。另外,探讨了其他形状的有限体积的含水构造超前探测异常规律,提出了“等效球体”的概念,亦在全空间球体含水构造超前探测解析公式的基础上设计了快速反演方法。最后,利用物理模型试验验证了有限元数值正演方法和阻尼最小二乘反演技术的可行性和有效性,为实际工程中含水构造的直流电法超前预报奠定了基础。     

Estimation of land subsidence caused by loss of smectite-interlayer water in shallow aquifer systems

Traditionally, land subsidence that results from groundwater over-pumping has often been described by the theory of consolidation. The mechanism of land subsidence due to the dehydration of clay minerals is not well addressed. A model of the “hydration state of smectite”, and a “solid solution model of smectite dehydration”, incorporating a thermodynamic solid solution model and laboratory results concerning clay-water systems of swelling pressure, hydration state and basal spacing in smectite interlayer, are employed to examine the effect of the release of water from the smectite interlayer on land subsidence in the coastal area of the Chou-Shui River alluvial fan and the Yun Lin offshore industrial infrastructure complex in Taiwan. The results indicate that 9.56–22.80% of the total cumulative land subsidence to a depth of 300 m is consistent with smectite dehydration following the over-pumping of groundwater. This dehydration-related land subsidence occurred to a depth of 0–60 m, with subsidence due to smectite dehydration accounting for 6.20–13.32% of the primary consolidation. Additionally, the total amount of subsidence resulting from both smectite dehydration and primary consolidation is consistent with the subsidence observed in the field. This study reveals that smectite dehydration appears to be important in assessing and predicting land subsidence in shallow aquifer systems.     

考虑固结的透水管桩沉桩全过程有限元模拟

运用透水管桩技术加快沉桩后桩周土体内超静孔隙水释放,进而消除沉桩施工中超静孔压的不利影响。基于有限元数值计算法,利用ABAQUS有限元软件建立透水管桩模型,实现透水管桩贯入过程以及桩周土体固结过程模拟。对比CEM圆柱孔扩张理论验证数值计算结果;阐述透水管桩贯入过程中位移场以及超静孔压场变化规律;对比分析静压桩和透水管桩桩周土体固结性状,结果表明透水管桩能加速超静孔压消散,短期内实现桩基承载力的快速提升。     

高密度电法多排列连接方法在工程勘察中的应用

高密度电法勘探的测线一般由多个排列组合而成,在工程勘察中将多排列数据连接起来进行处理和解释,使解释数据更加方便、直观和准确。结合工程实例,对高密度电法多排列连接方法进行研究,探讨方法的可行性。     

Remediation of ground water containing chlorinated and brominated hydrocarbons, benzene and chromate by sequential treatment using ZVI and GAC

A laboratory experiment with two sequenced columns was performed as a preliminary study for the installation of a permeable reactive barrier (PRB) at a site where a mixed ground water contamination exists. The first column contained granular zero valent iron (ZVI), the second column was filled with granular activated carbon (GAC). Trichloromethane (TCM, 930 μg/l) and chlorobenzene (MCB, 260 μg/l) were added to the ground water from the site as the main contaminants. Smaller amounts (<60 μg/l) of benzene, 1,2-dichloroethane, 1,1,2-trichloroethane (1,1,2-TCA), 1,1-dichloroethene (1,1-DCE), trichloroethene (TCE), tetrachloroethene (PCE), 1,2-dichloropropane (1,2-DCP), bromodichloromethane (BDCM), dibromochloromethane (DBCM), tribromomethane (TBM), vinyl chloride and chromate were also added to the water to simulate the complex contamination pattern at the site of interest. PCE, TCE, 1,1-DCE, DBCM, BDCM, TBM, MCB and chromate were remediated in contact with ZVI, while the remaining contaminants showed incomplete degradation. A fraction of 8–16.5% TCM was converted to dichloromethane (DCM). Remaining contaminant concentrations were efficiently sorbed by the GAC until breakthrough of DCM was observed after 1,230 exchanged pore volumes in the GAC. The results show that the complex mixture of contaminants can be remediated by a sequenced PRB consisting of ZVI and GAC and that DCM sorption capacity is the critical parameter for the dimensions of the GAC reactor.     

边坡非线性位移的分段最小二乘-时间序列分析

利用最小二乘法对位移时间序列进行分段拟合以提取时间序列的趋势项，从而将非稳定时间序列稳定化，对去除趋势项的稳定时间序列即残差进行常规AR（p）时序分析。结合滚动预测方法，建立边坡失稳预测的叠合模型，以长江三峡某边坡为例，对该模型进行的检验表明：新模型的预测精度较高、实时可靠。     

直流电法仪原理及其在探测矿井积水灾害中的应用

介绍了DZ—IIA直流电法仪的组成、工作原理,对直流电法勘探技术预测矿井水文地质灾害危险技术进行了可行性分析,重点阐述了DZ—IIA直流电法仪在防治水方面的应用效果。     

基于PSO和LSSVM的边坡稳定性评价方法

提出了基于粒子群算法（PSO）和最小二乘支持向量机（LSSVM）的边坡稳定性评价方法。该模型既利用了最小二乘支持向量机求解速度快、易于描述非线性关系的优良特性,同时也利用了粒子群算法快速全局优化的特点。粒子群算法用于搜索最小二乘支持向量机模型的最优参数,然后将模型用于预测边坡的安全系数。计算结果表明,该方法是合理的、有效的。     

松辽盆地南部海坨子地区超低渗透储层特征与形成因素

通过详细的岩心观察和描述,同时结合铸体薄片、扫描电镜、X-射线衍射、压汞、核磁共振以及物性等资料的研究,认为海坨子地区扶余油层为末端扇中部亚相沉积,储层岩石类型主要为岩屑长石砂岩和长石岩屑砂岩,孔喉结构为小孔隙、细喉或微细喉型,束缚水饱和度高,渗流能力差,属于超低渗透储层。沉积作用和成岩作用是扶余油层超低渗透储层形成的关键。末端扇沉积控制了扶余油层原始沉积物的粒度、碎屑成分以及填隙物成分和含量,使得储层初始孔渗性较差,同时强烈的机械压实作用导致扶余油层原生粒间孔隙体积直线下降,而胶结作用,尤其碳酸盐连晶状基底胶结几乎完全封堵了孔喉,喉道内伊利石等粘土矿物的搭桥生长,也使孔喉变得越来越曲折、狭窄,储层渗流能力因此遭受严重破坏。此外,末端扇储层中大量非渗透性隔夹层导致的强非均质性也是超低渗透储层形成的一个因素。溶蚀作用对扶余油层渗透性的改善有限,但成岩微裂缝和构造裂缝的发育对海坨子地区超低渗透油藏的开发起着至关重要的作用。