三维地震勘探在构造复杂地区的应用

山西某勘探区地形较平坦,相对高差较小,地表多为第四系黄土覆盖,零星有基岩出露,岩石风化严重,无潜水位．激发条件较复杂。该区主要可采3^#煤层埋藏最浅为75m,最深处245m,层位沉积不稳定．厚度变化剧烈;15^#煤层上距3^#煤层90m±,沉积相对稳定。该区二煤层形成的反射波T3和T15波虽可辨认,但因煤层埋深较浅．易受浅层干扰,有效叠加次数减少。通过实验,确定了激发及接收参数;在资料处理上利用叠前及叠后反褶积以提高分辨率：在解释中,充分利用水平切片、层拉平切片等方法,结合相干体、方差体技术进行相关特征对比及验证,有效识别出勘探区内的断层、陷落柱、采空区、无煤及薄煤区,为煤矿生产提供了可靠的地质保障。     

陷落柱的高斯射线束法模拟

以山西潞安矿区地层为参照,建立圆锥状陷落柱模型,模型区域为[0,1000]×[0,600]。分别在模型（0,0）、（250,0）和（500,0）三点激发,101道接收,道距10m。采用高斯射线束法对陷落柱模型进行地震射线追踪,模拟结果表明陷落柱柱面产生的反射波只有小部分能为地表所接收,难以形成能量可观的连续的反射波。另外根据射线路径,提出了延迟反射波（包括“反射—透射波”和“透射—反射波”）的概念,认为延迟反射波是在地表一定范围内可以接收到的陷落柱的特征波,它对CMP道集、水平叠加及偏移处理均会造成影响,从而影响陷落柱的地震解释精度。延迟反射波很可能就是实际揭露陷落柱规模小于地震资料解释结果的原因之一。     

三维地震勘探技术在潞安矿区的应用

潞安矿区属黄土丘陵地貌,浅层地震地质条件较好,但由于矿区内村庄、工业矿区等地面建筑较多,严重影响数据采集质量。目前潞安矿区三维地震勘探存在的主要问题为：小构造遗漏较多,特别是5m以下的断层和20m以下的陷落柱;陷落柱的解释误差较大,影响巷道及工作面布置;时深转换不准确,煤层底板等高线出入较大;第四系厚度不准。虽然受测区地震地质条件和技术限制存在多解性和误差,但就潞安矿区已开展的三维地震勘探来看,采区三维地震勘探是潞安矿区精细化地质勘查的必要手段,其在煤矿生产的合理设计、采区的合理划分及巷道、工作面的合理布置等方面发挥了重要作用。     

Evaluating the transport and removal of chromate using pyrite and biotite columns

To remove chromate from a wastewater, a porous permeable reactive barrier system (PRBS), using pyrite and biotite, was adapted. This study included bench‐scale column experiments to evaluate the efficiency of the PRBS and investigate the reaction process. The total chromium concentration of the effluent from the biotite and pyrite columns reached the influent concentration of 0·10 mM after passing through more than 150 pore volumes (PVs) and 27 PVs respectively, and remained constant thereafter. The Cr^VI concentration in the effluent from the biotite column became constant at about 0·08 mM , accounting for approximately 80% of the influent concentration, after passing through 200 PVs. Moreover, in the pyrite column, the Cr^VI concentration remained at about 0·01 mM , 10% of the input level, after passing through 116 PVs. This shows that both columns maintained their levels of chromate reduction once the Cr^VI breakthrough curves (BTCs) had reached the steady state, though the steady‐state output concentration of total chromium had reached the influent level. The variances of the iron concentration closely followed those of the chromium. The observed data for both columns were fitted to the predicted BTCs calculated by CXTFIT, a program for estimating the solute transport parameters from experimental data. The degradation coefficient µ of the total chromium BTCs for both columns was zero, suggesting the mechanisms for the removal of chromate limit the µ of the Cr^VI BTCs. The Cr^VI degradation of the pyrite column (6·60) was much greater than that of the biotite column (0·27). In addition, the Cr^VI retardation coefficient R of the pyrite column (253) was also larger than that of the biotite column (125). The R values for the total chromium BTCs from both columns were smaller than those of the Cr^VI BTC. Whereas the total chromium BTC for the pyrite column showed little retardation (1·5), the biotite column showed considerable retardation (80). The results for the 900 °C heat‐treated biotite column were analogous to those of the control column (quartz sand). This suggests that the heat‐treated biotite played no role in the retardation and removal of hexavalent chromium. The parameters of the heat‐treated biotite were calculated to an R of 1·2 and µ of 0·01, and these values confirmed quantitatively that the heated biotite had little effect on the transport of Cr^VI. These solute transport parameters, calculated by CXTFIT from the data obtained from the column tests, can provide quantitative information for the evaluation of bench‐ or field‐scale columns as a removal technology for Cr^VI in wastewater or contaminated groundwater. Copyright © 2006 John Wiley & Sons, Ltd.     

基于PSO的钢管混凝土减震框架小震作用下优化分析

基于粒子群算法,以钢管混凝土框架的层间位移角及构件内力为约束条件、防屈曲支撑核心单元横截面积总和为目标函数,采用Matlab编写了适用于钢管混凝土减震框架的优化算法,并对钢管混凝土减震框架进行了优化分析。结果表明:采用粒子群算法对钢管混凝土减震框架进行参数优化是可行的。粒子群算法参数少、收敛速度快,是一种适用于钢管混凝土减震框架的新型优化方法。     

Analysis of shear‐dominated RC columns using the nonlinear truss analogy

This paper uses nonlinear truss models for the analysis of shear‐dominated reinforced concrete (RC) columns subjected to cyclic loading. A previously established method, aimed to the analysis of RC walls, is enhanced to allow simulations of column members. The concrete constitutive equations are modified to account for the contribution of the aggregate interlock to the shear resistance. Additionally, an equation is proposed to determine the inclination angle of the diagonal members in the truss models. The modeling approach is validated using the results of quasi‐static and dynamic tests on shear‐dominated RC columns. The combination of predictive capabilities and conceptual simplicity establishes truss‐based models as an attractive approach for the systematic analysis of shear‐dominated RC frame construction. Copyright © 2014 John Wiley & Sons, Ltd.     

Tests and model calibration of high‐strength steel tubular beam‐to‐column and column‐base composite joints for moment‐resisting structures

Performance‐based engineering (PBE) methodologies allow for the design of more reliable earthquake‐resistant structures. Nonetheless, to implement PBE techniques, accurate finite element models of critical components are needed. With these objectives in mind, initially, we describe an experimental study on the seismic behaviour of both beam‐to‐column (BTC) and column‐base (CB) joints made of high‐strength steel S590 circular columns filled with concrete. These joints belonged to moment‐resisting frames (MRFs) that constituted the lateral‐force‐resisting system of an office building. BTC joints were conceived as rigid and of partial strength, whereas CB joints were designed as rigid and of full strength. Tests on a BTC joint composed of an S275 steel composite beam and high‐strength steel concrete‐filled tubes were carried out. Moreover, two seismic CB joints were tested with stiffeners welded to the base plate and anchor bolts embedded in the concrete foundation as well as where part of a column was embedded in the foundation with no stiffeners. A test programme was carried out with the aim of characterising these joints under monotonic, cyclic and random loads. Experimental results are presented by means of both force–interstory drift ratio and moment–rotation relationships. The outcomes demonstrated the adequacy of these joints to be used for MRFs of medium ductility class located in zones of moderate seismic hazard. Then, a numerical calibration of the whole joint subassemblies was successfully accomplished. Finally, non‐linear time‐history analyses performed on 2D MRFs provided useful information on the seismic behaviour of relevant MRFs. Copyright © 2015 John Wiley & Sons, Ltd.     

高铁路基粗颗粒土水力学参数测试方法研究

高铁路基粗颗粒土的水力学特性对路基内部水分运移及路基的长期累积变形有重要影响。而对这种高压实度的粗颗粒土,常规非饱和土试验仪器存在试样尺寸小、制样难度大的缺点,难以应用。介绍了一种用于测试高压实度路基粗颗粒土-水力学参数的试验装置,利用张力计和时域反射计量器,分别测量路基粗颗粒土在浸湿、干燥阶段不同高度处土体基质吸力、介电常数的变化情况,获得高压实度下高铁路基粗颗粒土土-水特征曲线;并通过瞬态剖面法获得路基粗颗粒土非饱和渗透系数与基质吸力的关系。试验结果表明,该套装置能够适用于最大粒径为20 mm的粗颗粒土,试样压实度最大可达到0.95。通过对一组试验结果分析,并结合Ekblad等试验结果,发现随着填料细颗粒含量增大,?（与进气值有关的参数）值逐渐减小,土体进气值增加;粒径越大,细颗粒含量越低,土体储水能力越低,对应n（与排水程度有关的参数）值越大。为路基粗颗粒土-水力学参数的测定提供了方法。     

Recent progress of seismic research on tall buildings in China Mainland

To study the seismic behavior of high strength concrete fi lled double-tube(CFDT) columns,each consisting of an external square steel tube and an internal circular steel tube,quasi-static tests on eight CFDT column specimens were conducted.The test variables included the width-to-thickness ratio(β1) and the area ratio(β2) of the square steel tube,the wall thickness of the circular steel tube,and the axial force(or the axial force ratio) applied to the CFDT columns.The test results indicate that for CFDT columns with a square steel tube with β1 of 50.1 and 24.5,local buckling of the specimen was found at a drift ratio of 1/150 and 1/50,respectively.The lateral force-displacement hysteretic loops of all specimens were plump and stable.Reducing the width-to-thickness ratio of the square steel tube,increasing its area ratio,or increasing the wall thickness of the internal circular steel tube,led to an increased fl exural strength and deformation capacity of the specimens.Increasing the design value of the axial force ratio from 0.8 to 1.0 may increase the fl exural strength of the specimens,while it may also decrease the ultimate deformation capacity of the specimen with β1 of 50.1.     

Modeling of the composite action in fully restrained beam‐to‐column connections: implications in the seismic design and collapse capacity of steel special moment frames

This paper investigates the effect of the composite action on the seismic performance of steel special moment frames (SMFs) through collapse. A rational approach is first proposed to model the hysteretic behavior of fully restrained composite beam‐to‐column connections, with reduced beam sections. Using the proposed modeling recommendations, a system‐level analytical study is performed on archetype steel buildings that utilize perimeter steel SMFs, with different heights, designed in the West‐Coast of the USA. It is shown that in average, the composite action may enhance the seismic performance of steel SMFs. However, bottom story collapse mechanisms may be triggered leading to rapid deterioration of the global strength of steel SMFs. Because of composite action, excessive panel zone shear distortion is also observed in interior joints of steel SMFs designed with strong‐column/weak‐beam ratios larger than 1.0. It is demonstrated that when steel SMFs are designed with strong‐column/weak‐beam ratios larger than 1.5, (i) bottom story collapse mechanisms are typically avoided; (ii) a tolerable probability of collapse is achieved in a return period of 50 years; and (iii) controlled panel zone yielding is achieved while reducing the required number of welded doubler plates in interior beam‐to‐column joints. Copyright © 2014 John Wiley & Sons, Ltd.