恭城—栗木断裂带的应变特征与变形环境探讨

通过系统的有限应变测量与差异应力估算,探讨了恭城—栗木断裂带的应变特征与变形环境,以其推动该断裂带的研究向更深层次发展。结果表明：①付林指数K的变化范围为0.32～1.67;应变主轴平均方位为276°∠21°,与断裂带的整体逆冲方向基本一致;断裂带的平均应变程度为2.26～3.00,属中等应变程度;断裂带的应变类型属压扁型应变与单剪型平面应变的一种复合叠加类型。②断裂带的差异应力值为40～80 MPa,变形深度小于10 km,属半脆性—半韧性的变形域。③断裂带的应变特征与变形环境及宏观构造样式基本吻合。     

IEC的风机选型参数估算方法在中国的适用性研究

国际电工委员会编制的《风力发电机组设计要求》(IEC 61400-1)推荐了针对风电机组安全等级评估的极端风速和湍流强度特征值估算方法,因其简单便捷,在风电领域被广泛采用。利用全国风能资源专业观测网的193座测风塔观测数据,对IEC推荐的极端风速计算方法与我国规范推荐的基于极值I型概率分布方法进行比较,发现两种方法计算的193座塔70 m高度层50年一遇10 min平均最大风速,仅有7座测风塔较为一致,差异在±1%;IEC推荐方法的计算结果多数偏小,其中偏小10%以上的测风塔有121座,偏小30%以上的有44座测风塔,而偏大10%以上的只有9座测风塔;IEC方法计算的极值风速大幅度偏小的测风塔主要分布在台风影响的东南沿海地区,偏差较小的测风塔主要分布在西北和华北地形平缓区域,但同时偏大10%以上的测风塔也多分布在这一地区。以目前行业领域普遍采用的以15 m·s~(-1)风速的平均湍流强度作为风电机组选型指标,与严格按照规范,以15 m·s~(-1)风速段所有样本湍流强度的90%分位数处的值作为指标进行风电机组等级确定作对比,发现193座塔中有46座塔的选型是不安全的,甚至相差两个等级。     

污染分布下的Lp估计抗差测度

观测数据中含有粗差或异常值扰动的误差分布可视为污染分布。根据M估计理论,导出了Lp估计的影响函数,分析了Lp估计的抗差能力,并用效率来测度估计的优劣、综合抗差能力和效率,指出观测数据中含有粗差的扰动,应用p为[1．2．1．5]的Lp估计来进行处理。     

Modeling the influence of settling velocity on cohesive sediment transport in Tanshui River estuary

Settling velocities of suspended cohesive sediment in estuaries vary over a range of several orders in magnitude. Variations in the suspended sediment concentration are often considered as the principal cause. Turbulence and the suspended sediment concentration, as well as other factors such as salinity, dissolved organic substances, flocculation ability, and the rate of floc growth affect setting velocities. A laterally–averaged finite difference model for hydrodynamics and cohesive sediment transport is developed and applied in the Tanshui River estuary, Taiwan. The model has been calibrated and verified with water surface elevation, longitudinal velocity, salinity, and cohesive sediment measured. The overall performance of the model is in qualitative agreement with the available data. The model is used to investigate the influence of settling velocity on cohesive sediment transport dynamics. The simulation indicates that the turbidity maximum zone is near Kuan–Du. When settling velocities increase the surface cohesive sediment concentration at Kuan–Du station trends to decrease and bottom cohesive sediment concentration increases. Both surface and bottom cohesive sediment concentrations decrease at Taipei Bridge and Pa–Ling Bridge. This implies that suspended sediment advected seaward and deposited. There is consequently a net seaward flux of suspended sediment near surface, and a net landward flux near the bed.     

Flood risk analyses—how detailed do we need to be?

Applied flood risk analyses, especially in urban areas, very often pose the question how detailed the analysis needs to be in order to give a realistic figure of the expected risk. The methods used in research and practical applications range from very basic approaches with numerous simplifying assumptions up to very sophisticated, data and calculation time demanding applications both on the hazard and on the vulnerability part of the risk. In order to shed some light on the question of required model complexity in flood risk analyses and outputs sufficiently fulfilling the task at hand, a number of combinations of models of different complexity both on the hazard and on the vulnerability side were tested in a case study. The different models can be organized in a model matrix of different complexity levels: On the hazard side, the approaches/models selected were (A) linear interpolation of gauge water levels and intersection with a digital elevation model (DEM), (B) a mixed 1D/2D hydraulic model with simplifying assumptions (LISFLOOD-FP) and (C) a Saint-Venant 2D zero-inertia hyperbolic hydraulic model considering the built environment and infrastructure. On the vulnerability side, the models used for the estimation of direct damage to residential buildings are in order of increasing complexity: (I) meso-scale stage-damage functions applied to CORINE land cover data, (II) the rule-based meso-scale model FLEMOps+ using census data on the municipal building stock and CORINE land cover data and (III) a rule-based micro-scale model applied to a detailed building inventory. Besides the inundation depths, the latter two models consider different building types and qualities as well as the level of private precaution and contamination of the floodwater. The models were applied in a municipality in east Germany, Eilenburg. It suffered extraordinary damage during the flood of August 2002, which was well documented as were the inundation extent and depths. These data provide an almost unique data set for the validation of flood risk analyses. The analysis shows that the combination of the 1D/2D model and the meso-scale damage model FLEMOps+ performed best and provide the best compromise between data requirements, simulation effort, and an acceptable accuracy of the results. The more detailed approaches suffered from complex model set-up, high data requirements, and long computation times.     

2022年1月8日青海门源6.9级地震机器学习地震预警震级估计与现地阈值报警的回溯验证

2022年1月8日1时45分青海省海北州门源县发生6.9级地震, 周边地区普遍有感, 并导致多条高铁线路临时停运. 本文利用这次地震获取的大量烈度计加速度记录, 基于正在进行系统研发的机器学习地震预警方法模块, 对地震预警震级估计与现地阈值报警进行了回溯验证. 结果表明: 在地震发生后3.1 s, 震级估计为6.5级, 且震级估计误差不受信噪比和震中距变化的影响, 随着首台触发后时间的增加, 震级估计逐渐接近实际震级. 对于现地地震动速度峰值PGV(Peak Ground Velocity)预测, 各个台站在P波到达后3 s时, 预测PGV与观测PGV呈现1:1线性关系, 随着P波到达后时间窗的增加, 预测PGV逐步接近观测PGV, 且PGV预测误差不受信噪比和震中距变化的影响. 现地台站仪器烈度阈值设置为Ⅵ度时, 报警成功、误报、漏报的百分比分别为99.53%、0%、0.47%, 平均预警时间为19.62 s, 且地震烈度Ⅵ度区内没有发生误报和漏报; 现地台站仪器烈度阈值设置为Ⅶ度时, 报警成功、误报、漏报的百分比分别为99.77%、0%、0.23%, 平均预警时间为9.69 s, 且地震烈度Ⅶ度区内没有发生误报和漏报. 此次回溯验证结果表明: 机器学习方法在这次地震中可以得到鲁棒的震级估计和现地阈值报警结果, 并为该方法的在线测试以及中国地震预警系统升级提供可行性依据; 其次, 在这次地震事件中, 烈度计可为预警提供额外的作用, 这也为烈度计在未来地震预警的研究和应用中提供了更多的可能性.

     

抗差估计的初值选择

对L1 范估计的平差值和LS估计的平差值作为抗差估计的初值进行了比较 ,指出在 ρ函数是严凸函数时 ,二者无明显的区别。因为LS估计简单且易于计算 ,因此建议用LS估计的平差值作为抗差估计的初值。     

基于反算原理的滑坡推力简易估算

滑坡滑面的抗剪强度指标往往用反算法确定。分析表明,对已变形位移的滑坡,其推力可不反算滑面抗剪强度指标而直接按现状稳定系数和设计安全系数简易地估算,一般地,滑坡推力等于下滑分力乘以设计安全系数相对于现状稳定系数的提高比例值。进而讨论了其对不同设计工况、各种典型形状滑面的适用条件。这是一条估算滑坡推力的捷径。     

滇西大理至瑞丽铁路沿线地温场特征及其工程地质意义

在整理、分析云南大理至瑞丽拟建铁路沿线及其邻区现今地温场分布特征的基础上,进一步总结前人的资料,综合研究、探讨了该区地温场与岩浆活动、活动构造、地震活动、区域深部构造的关系。结果表明,该区中高温温泉（中高地温场）的空间分布与地表岩浆岩的出露、地表主要活动断裂带的分布都具有较好的对应关系。综合研究后认为,该区的中高温温泉可归结为岩浆热源型、断裂深循环型和岩浆热源叠加断裂深循环作用型3种基本成因类型。同时还发现,该区的温泉分布与区域地震活动空间上也存在密切的关系,并据此将区内划分为4个地震区带。研究结果表明,本区地表温泉分布所反映出的地温场特征对本区的工程稳定性评价具有重要的指示意义。