软土固结系数确定方法的研究及应用

在砂井地基固结度计算中,土的固结系数是一个十分重要的参数,土的固结系数通常通过室内试验求得,但室内取得水平向固结系数制样比较困难。利用软基处理过程中孔隙水压力监测资料来推算软土的固结系数,并和室内试验加以对比分析,总结出二者之间的相互关系及变化规律,可供同类工程设计借鉴。     

带结构面围岩山岩压力计算探讨

岩体内存在着节理、断层、软弱夹层、岩层层面、片理、片麻理等各种结构面,结构面的不同组合,形成了形状不一、规模不等的各种结构体。给出了两组同倾向结构面、多组同倾向结构面、两组反倾向结构面,在不同倾角组合、不同计算条件下山岩压力的计算模式,并进行了比较分析,得出了有益的结论。     

地质钻探中的井漏及堵漏材料研究

通过对钻探过程中井漏的复杂地质因素分析,提出了水化膨胀复合材料体系,并对该体系进行了膨胀性、封堵性及复合桥接堵漏模拟实验。实验结果表明,堵漏材料PAR具有很强的吸水膨胀性能,可膨胀至原体积的几十倍,且时间快有利于形成快速的封堵。材料PAR与稻谷和锯末形成的复合堵漏材料具有很强的堵塞率,可达70%以上。承压堵漏测量装置中测试表明:复合堵漏体系不仅能形成封堵,而且能够承受一定的压差。在云南临仓市勐简乡铅锌矿钻探过程中,运用复合堵漏体系满足了该地区复杂地矿钻探需要。     

REE, Mn, Fe, Mg and C, O Isotopic Geochemistry of Calcites from Furong Tin Deposit, South China: Evidence for the Genesis of the Hydrothermal Ore-forming Fluids

The Furong tin deposit in the central Nanling region, South China, consists of three main types of mineralization ores, i.e. skarn-, altered granite- and greisen-type ores, hosted in Carboniferous and Permian strata and Mesozoic granitic intrusions. Calcite is the dominant gangue mineral intergrown with ore bodies in the orefield. We have carried out REE, Mn, Fe, and Mg geochemical and C, and O isotopic studies on calcites to constrain the source and evolution of the ore-forming fluids. The calcites from the Furong deposit exhibit middle negative Eu anomaly (Eu/Eu*= 0.311–0.921), except for one which has an Eu/Eu* of 1.10, with the total REE content of 5.49–133 ppm. The results show that the calcites are characterized by two types of REE distribution patterns: a LREE-enriched pattern and a flat REE pattern. The LREE-enriched pattern of calcites accompanying greisen-type ore and skarn-type ore are similar to those of Qitianling granite. The REE, Mn, Fe, and Mg abundances of calcites exhibit a decreasing tendency from granite rock mass to wall rock, i.e. these abundances of calcites associated with altered granite-type and greisen-type ores are higher than those associated with skarn-type ores. The calcites from primary ores in the Furong deposit show large variation in carbon and oxygen isotopic compositions. The δ¹³C and δ¹⁸O of calcites are −0.4 to −12.7‰ and 2.8 to 16.4‰, respectively, and mainly fall within the range between mantle or magmatic carbon and marine carbonate. The calcites from greisen and altered granite ores in the Furong deposit display a negative correlation in the diagram of δ¹³C versus δ¹⁸O, probably owing to the CO₂-degassing of the ore-forming fluids. From the intrusion to wall-rock, the calcites display an increasing tendency with respect to δ¹³C values. This implies that the carbon isotopic compositions of the ore-bearing fluids have progressively changed from domination by magmatic carbon to sedimentary carbonate carbon. In combination with other geological and geochemical data, we suggest that the ore-forming fluids represent magmatic origin. We believe that the fluids exsolved from fractionation of the granitic magma, accompanying magmatism of the Qitianling granite complex, were involved in the mineralization of the Furong tin polymetallic deposit.     

Construction of three-phase data to model multiphase flow in porous media: Comparing an optimization approach to the finite element approach

Multiphase flow modelling is a major issue in the assessment of groundwater pollution. Three-phase flows are commonly governed by mathematical models that associate a pressure equation with two saturation equations. These equations involve a number of secondary variables that reflect the fluid behaviour in a porous medium. To improve the computational efficiency of multiphase flow simulators, several simplified reformulations of three-phase flow equations have been proposed. However, they require the construction of new secondary variables adapted to the reformulated flow equations. In this article, two different approaches are compared to quantify these variables. A numerical example is given for a typical fine sand.     

煤层底板承压含水体上带压开采研究

渭北煤田5、10号煤层底板以下的奥陶系灰岩强含水层,水头压力大,对采煤的威胁严重,历史上曾经发生多次底板突水事故,造成重大人员伤亡。以澄合矿区为例,研究了带压开采防治水的技术路线,提出了底板注浆加固的防治水方法,并成功应用于董家河煤矿,不仅安全开采了5号煤层,而且保护了渭北地区岩溶水的统一水位标高,使区内各岩溶大泉流量稳定、黄河湿地生态安全得以保证,促进了生物多样性和工农业用水安全,为渭北及华北型煤田底板承压水体上带压安全采煤找到了技术途径。     

Unveiling controls of the latitudinal gradient of surface pCO2 in the Kuroshio Extension and its recirculation regions（northwestern North Pacific） in late spring

In the northwestern North Pacific, annual net air-sea CO₂ flux is greatest in the Kuroshio Extension（KE） zone,owing to its low annual mean partial pressure of CO₂（pCO₂）, and it decreases southward across the basin. To quantify the influences of factors controlling the latitudinal gradient in CO₂ uptake, sea surface pCO₂ and related parameters were investigated in late spring of 2018 in a study spanning the KE, Kuroshio Recirculation（KR）, and...     

北部湾地区不同相对密度的海砂力学特性分析

为探究相对密度和有效围压对饱和海砂力学特性的影响,利用GDS动态三轴试验仪,对广西北部湾地区海砂开展了一系列固结排水三轴剪切试验,分析了相对密度、有效围压对饱和海砂强度特征、体变特征、割线模量以及摩擦角的影响规律。结果表明：随着围压的减小或相对密度的增大,试样体积应变不断增大,而相对密度或有效围压的增加均会提高试样的峰值强度,有效围压与峰值强度之间呈现良好的线性增长关系。随着围压的减小或相对密度的增大,应力相对软化系数、剪胀系数均不断增大,且有效围压与应力相对软化系数、剪胀系数分别呈线性和半对数线性相关。割线模量随轴向应变的增加整体呈衰减趋势,各试验工况下轴向应变为5%时试样的割线模量相比于轴向应变0.164%衰减了80%~90%。饱和海砂的峰值摩擦角随相对密度的增加而增大,随有效围压的增大而减小,相对密度D_r为50%时有效围压σ_c为50 kPa对应的峰值摩擦角是σ_c为200 kPa的1.098倍。     

海洋透光率仪的设计及其在初级生产力研究中的应用*

海洋浮游植物光合作用固碳在全球碳循环中扮演着极为重要的角色, 获取不同光衰减对应的海水深度, 对于采集水样用于海洋初级生产力的研究具有重要意义。本研究于国际上首次开发了无缆便携式海洋透光率仪, 特殊的光学结构设计和光谱滤光技术使得光谱响应在波段400~700nm范围内超过了同类海洋传感器, 特定光衰减下对应的深度误差小于0.5m。将本设备应用于南海中尺度涡旋初级生产力的研究中, 在采样率和自动化方面验证了仪器的便携性; 通过对涡旋中初级生产力的空间分布规律进行分析, 检验了仪器数据结果的可靠性。海洋透光率仪在价格、准确性、可靠度和操作的便携性上具有不可比拟的优势, 将在未来海洋生态环境的研究中发挥重要作用。     

万米级深海陶瓷耐压结构水下内爆流场数值模拟

耐压结构是深海潜器的重要组成部分,但在深海的高压环境中却存在内爆的风险。为研究陶瓷耐压结构水下内爆的流场特性,使用针对可压缩多相流问题开发的开源代码,采用直接数值模拟,应用自适应直角网格,对两种压力条件下的耐压结构水下内爆进行了数值模拟。通过低压模拟结果与理论解和试验值比较,验证了模拟方法的有效性,进而开展万米级深海陶瓷耐压结构水下内爆模拟。分析发现：陶瓷耐压结构发生内爆后,其内部气腔存在多次压缩—反弹现象,深海环境压力越大则反弹越不明显;气腔反弹阶段,在结构外部将产生数倍于深海环境压力的冲击波,且传播速度接近声速;冲击波压力峰值与到球心距离呈负指数幂函数关系;在相同深海环境压力下,耐压结构外部监测点的冲击波压力与球体半径呈正比例关系。