四川汶川8.0级地震山西数字强震动记录中水平单分向加速度峰值与矢量合成水平向加速度峰值的关系

利用2008年5月12日四川汶川8．0级地震山西数字强震动台网27个台的地震记录分析研究了水平向矢量合成加速度峰值PGAH与水平单分向加速度峰值PGAE—W和PGAN-s的关系,结果表明：PGAE-W和PGAN-s中较大值与PGHn比较接近,平均相对偏差为9％。因此,在某些有关地震加速度峰值的研究中,简单地采用PGAew和PGAN—s中较大值近似地代替水平加速度峰值PGAH是合理的。     

四川汶川8．0级地震山西数字强震动记录特征与分析

对2008年5月12日四川汶川8．0级地震,山西数字强震动台网27个台的地震加速度记录,进行了处理和分析,包括对加速度波形数据的基线校正,滤波,加速度傅立叶和反应谱计算,以及速度和位移计算。结果表明：局部场地的介质特性对地震动特征有相当大的影响,较厚的覆盖土层对较长周期的地震波有明显的放大作用。厚覆盖土层场地的强震动观测对自振周期较长建筑物的抗震设计具有重要的意义。     

土石混合体渗透性现场试坑试验研究

针对唐钢司家营铁矿Ⅲ采场露天转井下开采回填废石设计研究工程要求,在该矿区Ⅲ采场附近进行了大尺度现场渗透试验。开挖3个大尺寸试坑,在各试坑中分层回填不同粒径范围及厚度的废石（土）进行试坑注水试验;测定回填土石混合体的近似渗透系数,测试土石混合体的粒径组成,并计算出各坑土石混合体的平均粒径和非均匀度。试验研究发现,回填土石混合体的渗透系数分别随平均粒径与非均匀度的增大而增大。降低回填废石（土）的平均粒径和非均匀度可以有效降低回填废石层的渗透性。     

Estimation of hydraulic conductivity in an alluvial system using temperatures

Well water temperatures are often collected simultaneously with water levels; however, temperature data are generally considered only as a water quality parameter and are not utilized as an environmental tracer. In this paper, water levels and seasonal temperatures are used to estimate hydraulic conductivities in a stream-aquifer system. To demonstrate this method, temperatures and water levels are analyzed from six observation wells along an example study site, the Russian River in Sonoma County, California. The range in seasonal ground water temperatures in these wells varied from <0.2 degrees C in two wells to approximately 8 degrees C in the other four wells from June to October 2000. The temperature probes in the six wells are located at depths between 3.5 and 7.1 m relative to the river channel. Hydraulic conductivities are estimated by matching simulated ground water temperatures to the observed ground water temperatures. An anisotropy of 5 (horizontal to vertical hydraulic conductivity) generally gives the best fit to the observed temperatures. Estimated conductivities vary over an order of magnitude in the six locations analyzed. In some locations, a change in the observed temperature profile occurred during the study, most likely due to deposition of fine-grained sediment and organic matter plugging the streambed. A reasonable fit to this change in the temperature profile is obtained by decreasing the hydraulic conductivity in the simulations. This study demonstrates that seasonal ground water temperatures monitored in observation wells provide an effective means of estimating hydraulic conductivities in alluvial aquifers.     

Search for Transits of a Short-Period, Sub-Saturn Extrasolar Planet Orbiting HD 46375

Precise brightness measurements of HD 46375 have been acquired with an automatic telescope to search for transits of its short-period, sub-Saturn extrasolar planet. Transits of the companion do not occur, indicating that the inclination of the orbit i is less than 83 degrees and sini is less than 0.992. This upper limit on sini still preserves the possibility that the mass of the planet is less than Saturn's. Analysis of the photometry for HD 46375 reveals no photometric variability larger than 0.0001+/-0.0002 mag at the orbital period of the planet. This effectively eliminates starspots and stellar pulsations as the cause of the radial velocity variations used to infer the planet's existence.     

不同类别场地地震震动反应分析

场地指的是所研究的近地表地点附近的局部地质条件.工程场地是地震波传播的载体,地震波在不同场地中传播特性存在着差异,场地条件对地震波的传播有重要影响.