煤矿开采在煤系砂岩中形成现代陷落柱的实例

通 过 钱家 营井 田 203泥石 流 突发 事故 ,对 陷落 柱 的形 成机 理 作进 一步 的 研究 ,巷 道临 空 空间 、构 造破 碎带 、高压 地下 水 的存 在是 煤 系砂 岩地 层 中形 成现 代 陷落 柱的 主 要控 制因 素 。     

刘桥一矿陷落柱发育规律及含水性研究

根据刘桥一矿1971年建井至今发现的8个陷落柱实际资料，通过对揭露陷落柱的地质、水文地质及分布特征的分析，阐述了陷落柱发育的根基所在，对陷落柱发育规律及成因进行了探讨，对于含水陷落柱的注浆封堵、留设保护煤岩柱，以及本矿矿井的深部开采都具有借鉴意义。     

两次强冰雹超级单体风暴双偏振特征对比

利用S波段双偏振天气雷达资料、探空和地面常规气象观测资料及灾情调查, 对2020年6月25日河北省蠡县和2021年7月9日山东省章丘的两次特大冰雹超级单体风暴双偏振特征进行对比。结果表明:两次超级单体风暴均发生在西北气流形势下, 章丘风暴具有较强的对流有效位能、较大的湿度和较高的湿球0℃层高度。蠡县风暴强度明显大于章丘风暴, 但差分反射率柱和比差分相移柱高度明显低于章丘风暴。蠡县风暴弱回波区上方存在深厚的强度超过65 dBZ强回波悬垂, 即悬垂的冰粒子循环增长产生较大的冰雹粒子, 大的冰雹粒子进入下降通道后, 再次产生明显增长且更加不规则, 导致更强的水平极化反射率因子和更小的相关系数。湿度的垂直分布是风暴发展强度的关键环境因素之一。蠡县超级单体风暴的产生环境非常干, 章丘超级单体风暴的产生环境相对较湿。     

The Levant Slumps and the Phoenician Structures: collapse features along the continental margin of the southeastern Mediterranean Sea

Two distinct series of slumps deform the upper part of the sedimentary sequence along the continental margin of the Levant. One series is found along the base of the continental slope, where it overlies the disrupted eastern edge of the Messinian evaporites. The second series of slumps transects the continental margin from the shelf break to the Levant Basin. It seemed that the two series were triggered by two unrelated, though contemporaneous, processes. The shore-parallel slumps were initiated by basinwards flow of the Messinian salt, that carried along the overlying Plio-Quaternary sediments. Seawater that percolated along the detachment faults dissolved the underlying salt to form distinctly disrupted structures. The slope-normal slumps are located on top of large canyons that cut into the pre-Messinian sedimentary rocks. A layer of salt is found in the canyons, and the Plio-Quaternary sediments were deposited on that layer. The slumps are bounded by large, NW-trending faults where post-Messinian faulted offset was measured. We presume that the flow of the salt in the canyons also drives the slope-normal slumps. Thus thin-skinned halokynetic processes generated the composite post-Tortonian structural patterns of the Levant margin. The Phoenician Structures are a prime example of the collapse of a distal continental margin due to the dissolution of a massive salt layer.     

长平井田三维勘探精细构造解释

山西沁水盆地是一个构造残留型的富煤盆地,是我国最大的煤层气田。长平井田位于沁水盆地南部,是煤层气成藏的有利区域,且该区域煤层气的形成及分布以构造成因为主要因素。在三维地震勘探偏移数据体的基础上,对研究区域的速度进行标定,对层位、断层、陷落柱以及褶曲进行精细解释,获得该区域精细构造特征描述。与原二维构造特征对比发现：三维地震构造特征中的煤系地层走向和埋深与原二维构造特征基本一致;三维地震构造特征反映出沿走向上发育的多个短轴状展布小幅褶曲,新增断层19条和新增陷落柱24个;查明原二维构造特征与三维构造特征中不一致的一条断层和陷落柱的位置,获得对地下煤层精确的成像解释。通过该区测井资料验证,三维地震构造特征符合地下实际情况,验证了三维精细构造解释的准确性。     

水泥土搅拌桩桩身质量的电阻率分析

通过对某高速公路软基处理试验段水泥土搅拌桩芯样强度与电阻率指标的分析发现,水泥土搅拌桩的桩身质量与其施工工艺密切相关;在特定的施工工艺条件下,水泥掺入比与搅拌均匀性是影响桩身质量的2个重要因素;在相同深度处,桩身水泥土芯样的竖向电阻率高于其水平向电阻率;桩身水泥土芯样的电阻率与其无侧限抗压强度之间存在着很好的线性相关关系;水泥体芯样水平向电阻率的标准差在一定程度上反映了水泥掺入量和搅拌均匀性。综上所述,利用水泥土的电阻率及其相关指标对大规模施工条件下水泥土搅拌桩的桩身质量进行定量分析是一种经济、无损、简便和科学的方法。     

Seismic fracture evaluation of diaphragm joints in welded beam-to-box column moment connections

Steel box columns are widely used in steel building structures in Taiwan due to their dual strong axes. To transfer the beam-end moment to the column, diaphragm plates of the same thickness and elevations as the beam flanges are usually welded inside the box column. The electro-slag welding (ESW) process is widely used to connect the diaphragms to the column flanges in Taiwan because of its convenience and efficiency. However, ESW may increase the hardness of the welds and heat-affected zones (HAZs), while reducing the Charpy-V notch strength in the HAZ. This situation can cause premature fracture of the diaphragm-to-column flange welds before a large plastic rotation is developed in the beam-to-box column joints. To quantify the critical eccentricity and the effectiveness of fracture prediction, this study uses fracture prediction models and finite element model (FEM) analysis to correlate the test results. In this study, two beam-to-box column connection subassembly tests are conducted with different loading protocols and ESW chamber shapes. To implement a fracture prediction model, the material parameters are established from circumferential notched tensile tests and FEM analysis. Test results indicate that the fracture instances can be predicted on the basis of the cumulative plastic deformation in the HAZs. Analytical results indicate that fracture instances and locations are sensitive to the relative locations of the ESW joints and beam flange. Tests also confirm that the possible fracture of the diaphragm-to-column flange joints can be mitigated by enlarging the chamber of the ESW joint.     

A modified numerical calculation method of collapse pressure for thick-walled offshore pipelines

Considering the shear deformation and thickness stretching of large deformation, a modified numerical calculation method based on the thick shell theory is established to determine the collapse pressure of thick-walled pipes. Verification experiments are conducted on ten pipe specimens in hyperbaric chambers. The good agreement between experimental results and numerical predictions shows the validity and reliability of the new numerical calculation method. Combining DNV specification, the characteristic collapse pressure is also calculated for comparison. The difference between experimental results and DNV calculations illustrates the latter one is much conservative in predicting collapse pressure for thick-walled pipes. Sensitivity analysis on manufacturing imperfections and material properties is investigated for pipes with different D/t ratios. Thick-walled pipes are easier to be affected by initial ovality, residual stress and hardening factor. Based on the stress distribution at the moment of collapse, a novel discovery is found that the collapse pressure of thick-walled pipes is dominated by material plastic behavior.     

Geoarchaeological evidence on a Late Bronze Age earthquake,Ohrid Basin (North Macedonia)

Geoarchaeological investigations on the northeastern shore of Lake Ohrid revealed 3.5 m thick deepwater lacustrine sediments overlying terrestrial vegetation macrofossils, worked wood and abundant potsherds dated to the Late Bronze Age (LBA). Distinct contact of deepwater sediment with the sub-aerial weathered limestone bedrock point to a sudden increase in lake level. According to radiocarbon data, catastrophic flooding occurred shortly after 1214 yr bc. Because the area is located in a highly active seismic zone, we propose that this event was caused by tectonically induced, metre-scale coseismic subsidence related to faults bordering the Ohrid alluvial plain. Moreover, this event coincides well with a dramatic switch in the habitation and settlement strategy in the region. More important, however, is the finding that the age of the proposed massive tectonic event and change in habitation lies within the interval of the proposed ‘earthquake storm’ in the eastern Mediterranean dated to 1225–1175 bc. As the Ohrid-Korça zone belongs to the same tectonic province, a relationship between the abovementioned earthquakes and the proposed event can be expected. This research therefore might provide the first direct evidence of a large-scale earthquake event linkable to the LBA collapse of Europe's first urban civilisation in the Aegean.     

地震海洋学研究进展

传统船舶调查获取海洋水体温盐资料的方法在水平方向上分辨率较低,而用反射地震探测海洋水体特性的方法--地震海洋学,能有效提高海水温盐资料在水平方向上的分辨率.概述了近5年来地震海洋学的发展过程,重点介绍了地震海洋学方法在海洋锋面观测、水团边界划分、海洋内波分析、中尺度涡旋等方面的研究成果,以及AVO、全波形反演等反射地震处理方法在海洋水体特性研究中的应用.比较了地震海洋学方法与声层析技术、高频声技术等声学方法应用于海洋水体特性研究的异同.并展望了下一步研究工作的重点:①有关地震反射剖面的各种参数与海洋水体温盐结构物理模型的联系及其定量分析;②以研究海洋水体特性为目标的地震反射剖面的处理方法;③海洋地震调查历史数据的应用.