黏滑断层隧道减错措施参数对减错效果的影响分析

为提高黏滑断层隧道的结构安全性和稳定性,对黏滑断层隧道设置不同缝宽减错缝、不同刚度减错层的减错效果进行研究。研究结果表明:断层黏滑错动对上盘隧道的影响远大于下盘;减错缝对上盘部分隧道结构的减错效果优于下盘,其中上盘减错效果最大为24.50%,下盘减错效果最大为9.26%;减错层对下盘部分隧道结构的减错效果略优于上盘,其中下盘减错效果最大为105.32%,上盘减错效果最大为78.07%;随着减错缝宽度的增加,隧道上盘减错效果变好,下盘缝宽10—15cm减错效果最好;随着减错层弹性模量的增加,隧道上下盘减错效果降低,当减错层弹性模量增加到一定程度（约100MPa）,减错效果趋于稳定。研究成果可为黏滑断层隧道的减错结构设计及施工提供参考。     

对齐误差对测试地震计自噪声的影响

本文在理论上研究了对齐误差对测试地震计自噪声的影响。指出对齐误差影响到2台仪器记录间的计算互功率谱密度, 进而影响到被测仪器记录间相干函数计算, 最终影响到被测仪器的自噪声计算。发现当存在对齐误差时, 在信噪比较高频段计算得到的自噪声水平比仪器的实际自噪声水平要高, 在一般的实际测试中可能高20 dB以上。为了消除对齐误差对自噪声测试的影响, 提出通过投影逆变换把观测记录变换到标准坐标系下, 再用变换后的观测记录来计算地震计自噪声。给出了基于以上思路和传感参数对比测试方法的地震计自噪声计算处理流程, 合成数据、 实际测试数据的处理检验计算结果表明, 本文方法可以有效克服地震计自噪声测试中对齐误差的影响。     

萧山-球川断裂富阳—建德段第四纪活动性研究

萧山-球川断裂是浙江地区1条大规模的北东向断裂,在该断裂附近曾发生过多次破坏性地震。本文通过地质调查、电法勘探和探槽开挖等方法,对萧山-球川断裂富阳—建德段第四纪活动性进行了研究。萧山-球川断裂富阳—建德段的遥感影像线性特征清楚,对地貌的控制作用较为明显,对山前的第四系发育有明显影响。通过对断裂露头剖面的分析,认为萧山-球川断裂富阳—建德段活动性质以走滑兼具逆冲为主。通过本次开挖的富阳峙山村探槽,结合ESR年龄测定,判定该断裂在第四纪早、中期有过活动,但未断错上覆中更新统上部地层,其最新活动时代为早、中更新世。     

Bouguer gravity study of middle section of Tanlu fault

Although Tanlu fault is one of the most important tectonic fault zones and active earthquake belts in eastern China, little is known about its deep structure. In this study, we use the existing Bouguer gravity data to study the middle section of the Tanlu fault zone, which is also known as the Yishu fault zone. Our gravity inversion results indicate that the Moho has an abrupt offset in depth at the Tanlu fault zone and it has a relatively smooth variation away from the fault zone. The crustal structures on both sides are different from each other. Sediment is thin on the west side with an average thickness of less than 5 km, while it is as thick as 6 km on the east side. The thinnest sediment （3-4 km） is at the fault zone. Moho depth increases from 33 to 34 km on east side and from 36 to 38 km on west side. Tanlu fault zone is shown as a wide zone of linear gradient in the Bouguer gravity anomaly.     

A theory of efficiency of storage-treatment systems

A simple expression is presented on the capability of storage-treatment systems to reduce non-point pollutant runoff load to natural waters. Their efficiency depends on the capacities of the facilities and probabilistic properties of runoff, such as interval, duration, volume, and concentration of runoff events. Assuming the compound Poisson process for runoff time series, the exact expressions of the ratio of treated load in terms of storage and treatment capacities are theoretically derived on the neighbourhoods of all boundaries of the domain on which the problem is defined. Then, an approximate expression over the whole domain is presented, of which the value and the first-order derivative coincide with those of the exact derived expressions near the boundaries. Accuracy is checked by Monte Carlo simulations.     

基于人工电离层扰动对地-电离层波导传播的VLF波的影响

基于低电离层加热理论和甚低频电波在地-电离层波导中传播理论,建立低电离层扰动对甚低频电波传播影响的分析模型,并利用实验数据验证了该模型的正确性.据此模型,研究了加热功率、加热波极化以及背景参数所导致的低电离层扰动对不同频率甚低频电波传播的影响.结果表明,低电离层扰动越强,则通过该区域内甚低频波幅度和相位的相对变化越强,通过研究地-电离层波导甚低频信号通过人工扰动区域后幅度和相位的变化,可望用于诊断人工电离层扰动强度.     

鄱阳湖水利枢纽工程对湖泊水位变化影响的模拟

水位变化是影响湖泊水文过程和生态环境的重要因素.本研究基于环境流体动力学(EFDC)模型构建了鄱阳湖水利枢纽工程与主湖区的二维模型,模拟水利枢纽工程运行后对主湖区及湿地保护区水位变化节律的影响.模拟结果表明:水利枢纽工程对湖泊水位的影响由北向南逐渐减小,水利枢纽工程提升了大湖北部水位,使南北水位差减小,将影响鄱阳湖枯水期的流速及自净能力.吴城和南矶湿地自然保护区核心区水位变化受水利枢纽工程的影响较小,吴城自然保护区核心区在水位低于13.8 m时与大湖脱离,不再受水利枢纽工程影响,但水利枢纽工程会影响蚌湖与大湖脱离时间;南矶自然保护区位于鄱阳湖南部,水位受水利枢纽工程影响很小.水利枢纽工程条件下,湖泊水位受人工控制,枯水年和平水年湖泊水位的变化基本一致;枯水年水利枢纽工程对湖泊水位的影响大于平水年,但对湖泊南部的水位变化影响仍然较小.模型模拟结果可以揭示在目前调度方案下,水利枢纽工程对湖泊水位变化节律的影响规律,为工程建设提供一定的理论参考.     

秦岭北缘断裂带温泉水循环深度与地震活动性的关系研究

研究了秦岭北缘断裂带温泉水的氢氧同位素和氦同位素,同时通过温泉水的热储温度和当地地温梯度计算了温泉水的循环深度;统计分析了1900-1997年间的地震频度.从水对断裂及其围岩的弱化的角度讨论了温泉水深循环对地震活动性的影响.结果表明各段地震活动性的差异与温泉水循环深度的差异有关.认为循环深度较深的陕西段孕育强震的可能性较小,而循环深度较浅的青海段和甘肃段是孕育强震的危险区,其中甘肃段可能是强震的最危险区.     

Evaluation of the efficiency of a model of the decameter radiowave propagation environment

We present a concept regarding the effectiveness of ionospheric models in maximum usable frequency (MUF) forecasts according to the fitting criterion for daily progress in predicted and experimentally observed MUFs. For example, it is shown using the daily variability in the MUF on two one-leap paths that an MUF model on the basis of a long-term IPG forecast is characterized by efficiency within 0.8. It is shown using the same two paths that a forecast on the basis of the International Reference Ionosphere (IRI) model has the same efficiency. A model of the effectiveness probability density function is constructed on the basis of a generalization of the method of nonholomorphic functions.     

Winkler地基梁在温度场中受简谐激励3次超谐共振分析

本文研究W inkler地基梁在温度场中受简谐激励作用的3次超谐共振问题,应用弹性理论和Galerk in方法建立W inkler地基梁在温度场中受简谐激励作用的非线性动力方程,根据非线性振动的多尺度法求得系统满足3次超谐共振情况的一次近似解,分析了温度、阻尼、激励幅值、地基刚度等参数对系统的影响。     

西秦岭北缘断裂带特征地震平均复发间隔的确定和地震危险性评价

时间相依的地震危险性概率评估方法是最近10a来逐渐发展起来的，是一种将已获得的定量地质资料运用于活动断裂中—长期地震潜势概率评估的方法，从而使得在缺乏历史记载或仪器记录资料，但已获得断层平均滑动速率、同震位错、古地震年代序列等资料的活动断裂段上评估未来的发震概率成为可能。在定量计算活动断裂未来地震危险性的过程中，作为输入参数之一的特征地震平均复发间隔是一个至关重要的参数，它的确定将直接影响到概率计算的结果。对研究断裂上已获得的历史地震资料(H)、地质资料(G)和古地震资料(P)，笔采用了时间可预报(T)和准周期(Q)两种模式分别计算其平均复发间隔，比单一的只假定一种复发模式计算更具有完善性和可靠性。在叙述该方法的同时，以西秦岭北缘断裂为例，详细阐述了该断裂上特征地震平均复发间隔的确定，并在此基础上对西秦岭北缘断裂未来地震潜势作了定量评估。     

The effect of the pollution of the ground layer of the atmosphere on the albedo

Summary A simple model is proposed suitable for studying the effect of the ground layer of the atmosphere, polluted by aerosol, on the albedo. This model is founded on solving the equation of transfer of radiative energy. The numerical results are discussed, particular attention being paid to the analysis of errors due to neglecting the multiple reflection of solar radiation on the aerosol particles. A method which would also include the multiple reflection is proposed, and the conditions under which the presence of the aerosol is responsible for an increase or decrease of the solar radiation balance on the Earth's surface, are analysed.     

Effect of soil depth on inelastic seismic response of structures

Effect of depth of soil stratum on estimated inelastic displacement of three typical structures, viz. a four storey building, a continuous bridge, and a tower, is studied and adequacy of the site amplification models of the current design codes and available empirical relationships is examined. The structures are assumed to be located on well-defined sites with varying bedrock depths, and effect of depth on elastic response spectrum, site amplification factor, displacement modification factor and inelastic displacement is studied, numerically, for two values of PGA. It is observed that soil depth has a significant effect on elastic as well as inelastic response of the structures; however, the effect of soil amplification on inelastic response is not as pronounced as in case of elastic response. Therefore, use of empirical site amplification models based on elastic response may be too conservative, for estimating inelastic response.     

Theoretical Error Analysis of the Accuracy of Focal Depth Determination of Near Earthquakes

Focal depth is one of the most difficult seismic parameters to determine accurately in seismology. The focal depths estimated by various methods are uncertain to a considerable degree,which affects the understanding of the source process. The influence of various factors on focal depth is non-linear. The influence of epicentral distance,arrival time residual and velocity model (crust model) on focal depth is analyzed based on travel time formula of near earthquakes in this paper. When wave propagation velocity is constant, the error of focal depth increases with the increase of epicentral distance or the distance to station and the travel time residual. When the travel time residual is constant,the error of focal depth increases with the increase of the epicentral distance and the velocity of seismic wave. The study also shows that the location error perhaps becomes bigger for shallower earthquakes when the velocity is known and the travel time residual is constant. The horizontal error caused by location accuracy increases with the increase of the epicentral distance,the travel time residual and the velocity of seismic waves,thus the error of focal depth will increase with these factors. On the other hand,the errors of focal depth will lead to change of the origin time,therefore resultant outcomes will all change.     

Rayleigh波入射情形下的断层效应

本文运用数值模拟方法对Rayle igh波入射情形下的断层效应进行分析,结果表明:断层对Ray-le igh面波具有隔震作用,随断层深度的增加其隔震效果更加明显,且水平向的隔震效果强于竖向。在入射波一侧,由于断层的作用使接触带附近的反应增强,随着断层破碎带宽度的增加,竖向反应变化特征明显不同于水平向反应变化特征。     

敦煌莫高窟崖体锚索加固技术钻孔振动效应测试分析

机械设备施工所产生的振动对文物的影响问题已越来越引起人们的重视。如何科学合理地判定其影响程度并采取必要的防振对策，进行现场实地测试获取数据是非常必要的。针对莫高窟崖体的特点，对拟采用的锚索加固技术所产生的振动情况进行了分析测试，获得了不同距离处崖体不同方向的振动加速度和速度，较好地反映了该施工工艺引起的振动效应的实际情况，并对其安全性进行了评估，为莫高窟崖体的加固提供了重要依据。     

迭代法与FFT法位场向下延拓效果的比较

将水平观测面上的实测位场值，垂直投影至下部的延拓水平面上，作为该水平面上的位场初始值. 根据该水平面上的初始值，用快速傅里叶变换(FFT)的方法向上延拓计算观测面上的位场值. 用观测面上的实测值与计算值的差值，对延拓面上的位场值进行校正. 如此反复迭代，直至观测面上的实测值与计算值的差值小到可以忽略. 这种空间域的迭代法原理简单，不用解线性代数方程组，有较高的计算速度和良好的延拓效果. 本文用迭代法对模型数据和实际数据进行向下延拓，对比了迭代法与常规的FFT法在位场向下延拓中的效果，迭代法显著优于FFT法.     

坡地地形对地震动特性的影响分析

采用有限元有限差分方法，结合人工透射边界理论，研究局部坡地地形对地震动特性的影响，分析坡高、坡角对地形放大效应的影响。研究结果表明:坡地地形斜坡段各点反应谱谱比最大值沿坡高逐渐增大，坡脚点对地震动反应谱谱比呈缩小效应；坡底段各点反应谱谱比接近1；坡起平台段空间点受地形效应的影响较大；坡高和坡角对地形效应的影响较明显，当坡角不变时，不同坡高反应谱谱比曲线形状基本相同，峰值点对应的特征周期随着坡高的增加呈增长趋势，峰值点对应的反应谱谱比随着坡高的增加呈增大趋势，斜坡顶点阿里亚斯烈度比值在地形坡高超过一定数值后随着坡高的增加呈增大趋势；当坡高不变时，大部分频段内反应谱谱比最大值随着坡角的增加逐渐增大，斜坡顶点阿里亚斯烈度比值在坡角达到一定数值后随着坡角的增加呈增大趋势。     

延怀盆地构造特征及未来地震危险性评价

本文从延怀盆地的地质构造特征出发,依据近期各断层的滑动速率,由震级—时间可预测模型,计算了各断层的未来地震危险性。结果表明,未来延矾盆地北缘断裂的地震震级最大,预测的发震时间在该区域也是最早,而南口山前断裂未来发生地震的概率最大。     

相邻地形对地震动特性的影响分析

基于采用透射人工边界的显式动力有限元方法,研究了相邻凸起地形对地震动反应谱特性的影响,分析了相邻凸起之间距离的变化对地形效应的影响。研究结果表明：1）与单一凸起地形对地震动的放大效应相比,相邻地形的存在对地震动反应谱谱比曲线的形状影响不大,但是却对谱比的值具有较大影响,而且其影响程度的大小与地表观测点的位置有关;2）相邻凸起地形的存在对凸起平台段中点地震动高频成分的放大效应具有较大影响,随着相邻凸起之间距离的增大,该影响效应逐渐减弱,多个相邻凸起构成的组合地形对地震动的放大效应逐渐接近单一凸起地形。