城市垃圾填埋场地震稳定分析及永久位移计算

根据城市生活垃圾室内外试验结果,提出了确定浸润线自由面的方法．通过静力和动力有限元计算,对某填埋场边坡进行稳定分析,给出了在地震过程中每一小时段的稳定安全系数．结果表明,在地震过程中,最危险滑动面的位置比较稳定;在此基础上,对Newmark方法进行了改进,使之建立在比较精确的基础上,得到了填埋场在地震作用下的永久位移,对填埋场的抗震设计具有重要的指导意义．这一方法对一般坝体的工程抗震也有很大的参考价值．     

先期震动对土石坝地震永久变形的影响研究

针对经历了5.12汶川大地震的紫坪铺面板堆石坝工程,进行了坝料的大型动三轴试验,研究了先期振动对坝料残余应变的影响。在此基础上,采用基于3维非线性动力反应的地震永久变形计算方法,进行了紫坪铺面板坝地震永久变形的计算,重点分析了先期震动对坝体地震永久变形的影响。结果表明,如果考虑先期已遭受强震作用影响,大坝的地震残余变形明显减小。     

形变数字化观测对大陆地震响应能力及机理分析

在中国大陆2001年以来发生的数次5级以上地震前,山西侯马数字化形变台的波形记录发生了明显变化。本文就此进行了初步分析,认为强震前的预滑移可能产生这种长周期的形变波,它们对大震预报有一定意义。     

Slow earthquakes and great earthquakes along the Nankai trough

We have reexamined reports indicating that slow deformation occurred before the great Japan earthquakes of 1944 (Tonankai) and 1946 (Nankaido) and find that the observations are well founded. Although no quantitative models have previously been proposed to explain all of the relevant data we show that they are satisfied by a simple model for both earthquakes. The model, based on known properties of subduction zones, has slow slip on the subduction interface in an area deeper than the seismic rupture. If this model is correct and a similar physical situation holds for an anticipated Tokai earthquake, existing instruments will be able to reveal the pre-slip in real time. While differences among the deformation time series at different sites will provide strong constraints on the slow rupture propagation, these differences could result in delaying the recognition of a coherent event.     

Seismological evidence for nonlinear elastic ground behavior during large earthquakes

Amplification of earthquake-induced seismic waves by soft superficial deposits often causes significant damages in the urban areas. In predicting this effect for large future earthquakes, the linear elastic response of soils is customarily assumed. To check this assumption, we have analyzed surface and downhole acceleration data from the SMART1 and SMART2 strong motion arrays in Taiwan, covering peak accelerations of up to 0·3 g. First, frequency-dependent amplification induced by the alluvial deposits at the SMART1 array was estimated using spectral ratio technique, where the records at rock site were taken as a reference motion. Statistically validated reduction in soil amplification in the strong motion relative to the weak motion in the frequency range between approximately 1 and 9 Hz was detected. Secondly, relative site responses between the Pleistocene and recent sedimentary deposits at the SMART2 array were studied. Relative amplification was shown to be clearly dependent on the excitation level. Thirdly, we compared experimentally recorded uphole/downhole spectral ratios on weak and strong ground motion with the theoretical response yielded by the geotechnical code DESRA2 which assumes hysteretic constitutive relationship of soil. Major symptoms of nonlinear ground behavior predicted by the model were found in the observed data. Back-calculation of the shear wave velocities to the depth of 47 m shows nearly 50% decrease in the strongest quakes, also accounted for by the nonlinear soil behavior.     

多次透射公式实用形式稳定性分析

本文以二维出平面波动方程为例,利用数值方法研究了多次透射公式的实用形式的稳定问题,结果表明：多次透射公式的实用形式与波动方程的集中质量显式有限元结合,不但存在零频漂移,而且同样存在高频振荡失稳,而与中心差分方法结合仅存在零频漂移失稳。     

An elastic-plastic analysis of short-leg shear wall structures during earthquakes

Short-leg shear wall structures are a new form of building structure that combine the merits of both frame and shear wall structures. Its architectural features, structure bearing and engineering cost are reasonable. To analyze the elastic-plastic response of a short-leg shear wall structure during an earthquake, this study modified the multiple-vertical-rod element model of the shear wall, considered the shear lag effect and proposed a multiple-vertical-rod element coupling beam model with a new local stiffness domain. Based on the principle of minimum potential energy and the variational principle, the stiffness matrixes of a short-leg shear wall and a coupling beam are derived in this study. Furthermore, the bending shear correlation for the analysis of different parameters to describe the structure, such as the beam height to span ratio, short-leg shear wall height to thickness ratio, and steel ratio are introduced. The results show that the height to span ratio directly affects the structural integrity; and the short-leg shear wall height to thickness ratio should be limited to a range of approximately 6.0 to 7.0. The design of short-leg shear walls should be in accordance with the "strong wall and weak beam" principle.     

填充墙刚度设计分析

我国抗震规范中填充墙对结构刚度影响考虑比较粗略,震害调查发现实际工程中由于没有充分考虑填充墙对结构刚度的影响,填充墙布置不当,使结构造成不应有的破坏。利用现有结构设计程序,可以充分模拟填充墙的刚度,使得填充墙刚度直接参与到结构的空间分析中,从而得到相对更为准确的设计数据。尤其是对结构底层柱水平位移的分析和层间位移的分析,在结构抗震设计中非常重要。     

考虑刚度劣化的剪切带-围岩系统稳定性分析

峰后的刚度劣化现象（渐进损伤）在多种煤、岩石、混凝土、土和砂子的循环加载实验中已被观察到。本文考虑了剪切带及带外弹性体的不同的刚度劣化现象,推导了剪切带（断层）-弹性围岩系统在直剪条件下的应力-变形曲线。剪切带的刚度劣化不改变剪切带的总变形,但使剪切带的弹性变形增加、塑性变形降低。考虑弹性体的刚度劣化现象之后,系统的峰后应力-变形曲线呈现非线性特征,这不同于过去忽略刚度劣化现象的结果。在应变软化过程中,剪切带之外弹性体的刚度劣化,使系统的峰后响应由负斜率（Ⅰ类行为）变为正斜率（Ⅱ类变形行为）。较高的弹性体尺寸、较高的脆性、较小的内部长度、较低的围岩初始弹性模量、较高的抗剪强度、较低的残余剪切应力及较高的残余剪切弹性模量,使系统的峰后响应变得陡峭,甚至发生Ⅱ类行为,使系统的失稳（岩爆、冲击地压、采矿诱发地震或矿震）易于发生。     

Multifractal analysis of earthquakes

Multifractal properties of the epicenter and hypocenter distribution and also of the energy distribution of earthquakes are studied for California, Japan, and Greece. The calculatedD _q-q curves (the generalized dimension) indicate that the earthquake process is multifractal or heterogeneous in the fractal dimension. Japanese earthquakes are the most heterogeneous and Californian earthquakes are the least. Since the earthquake process is multifractal, a single value of the so-called fractal dimension is not sufficient to characterize the earthquake process. Studies of multifractal models of earthquakes are recommended. Temporal changes of theD _q-q curve are also obtained for Californian and Japanese earthquakes. TheD _q-q curve shows two distinctly different types in each region; the gentle type and the steep type. The steeptype corresponds to a strongly heterogeneous multifractal, which appears during seismically active periods when large earthquakes occur.D _q for smallq or negativeq is considerably more sensitive to the change in fractal structure of earthquakes thanD _q forq2. We recommend use ofD _q at smallq to detect the seismicity change in a local area.     

GM3磁通门磁力仪稳定性分析

通过2002～2003年的GM3磁通门磁力仪的资料,对该仪器的各项指标进行稳定性分析,考核运行状态是否正常,以证明是否替代模拟观测仪器。     

危岩体在地震作用过程中的失稳模式及稳定性评价

地震作用过程中地震加速度通常呈先增大后减小的特征。利用拟静力法对危岩的稳定性进行分析时,考虑地震过程中地震加速度的变化,对山西太原天龙山危岩体加固工程中的同一危岩体分别以滑塌式和倾倒式破坏模式进行计算,发现地震作用过程中危岩体可能在两种破坏失稳模式之间相互转化。将此问题扩展至一般情况进行计算并讨论,得出如下结论:地震力对危岩体破坏作用的贡献大小不同,通常情况下,地震作用力对危岩的倾覆力矩贡献相对较大;进行稳定性评价时应考虑地震作用过程,以安全系数最先达到1.0的破坏模式作为危岩体的可能破坏模式进行计算;对危岩体进行抗震加固设计时应对加固设计进行多种工况下的校核,保证其在地震作用过程中不同危险状态的稳定性。     

鲜水河断裂带蠕变观测与地震

统计了布设在鲜水河断裂带上的DSJ断层水平位移测量仪建场以来发生的“短周期事件”年频次，用消除年变、一阶差分等计算方法处理DSJ数据并与DSJ同一场地的短基线数据进行对比分析，结果显示：DSJ“短周期事件”有地震前兆意义，具有无震蠕滑性质：蠕变波是可以在同一断层上传播的，并可触发地壳破裂。     

Residual displacements of RC structures as SDOF systems

Residual displacements are sensitive to ground motion details, hence more random than peak inelastic displacements. Among the factors with systematic impact on residual displacements, the post‐yield‐stiffness‐ratio has been studied thoroughly; its effects are not investigated further. Concerning another important factor, the hysteresis law, past studies have focused on the bilinear model, which does not represent concrete structures. Residual displacements from nonlinear response‐history analyses of bilinear systems are compared to those from models tuned to concrete structures, conforming to modern codes, deficient or intermediate. Deficient‐type structures, with their narrow, almost self‐centering hysteresis loops, develop markedly smaller residual displacements than those with stable energy‐dissipating behavior. A velocity pulse in the motion increases peak inelastic and residual displacements by about the same proportion. As a fraction of the peak inelastic or spectral displacement, residual displacements are on average almost independent of the period and increase when the lateral strength ratio increases, reaching a limit at a lateral strength ratio of 2 to 5. Peak inelastic displacements are a better basis for estimation of residual displacements than spectral ones: the ratio of the two is almost independent of the period, the lateral strength ratio (beyond values of 2 to 3) and velocity pulses. The spectrum of the ratio of residual displacement to peak inelastic or spectral displacement is considered as a random process of period; its mean and variance functions, marginal probability distributions and autocorrelation functions are given in terms of the lateral strength ratio, the hysteresis model and the presence of a velocity pulse. Copyright © 2014 John Wiley & Sons, Ltd.     

油气井永久性光纤传感器的应用及其进展

论述了光纤传感器在油气藏永久监测中的应用及其进展,对分布式光纤温度传感器、基于干涉仪原理的光纤压力传感器以及多功能的光纤Bragg光栅传感器系统作了详细讨论．通过两个实例,来说明分布式温度光纤传感器系统(DTS)可以在井下解决的若干问题．最后,对光线传感器在油气生产及动态监测应用中存在的问题及发展趋势进行了讨论。     

Estimate of input energy for elasto‐plastic SDOF systems during earthquakes based on discrete wavelet coefficients

The response of an elasto‐plastic single degree of freedom (SDOF) system to ground motion is estimated based on wavelet coefficients calculated by discrete wavelet transform. Wavelet coefficients represent both the time and frequency characteristics of input ground motion, and thus can be considered to be directly related to the dynamic response of a non‐linear system. This relationship between the energy input into an elastic SDOF system and wavelet coefficients is derived based on the assumption that wavelets deliver energy to the structure instantaneously and the quantity of energy is constant regardless of yielding. These assumptions are shown to be valid when the natural period of the system is in the predominant period range of the wavelet, the most common scenario for real structures, through dynamic response analysis of a single wavelet. The wavelet‐based estimation of elastic and plastic energy transferred by earthquake ground motion is thus shown to be in good agreement with the dynamic response analysis when the natural period is in the predominant range of the input. Copyright © 2005 John Wiley & Sons, Ltd.     

Mechanisms of slip nucleation during earthquakes

Slip nucleation during earthquakes is apparently analogous to rupture nucleation within an intact rock sample subjected to triaxial loading. The observations indicate that both these nucleation processes initiate within a relatively small volume and in both the slip propagates unstably along a quasi-planar surface. In both processes a single, pre-existing, shear fracture cannot nucleate the large-scale slip, and in both a ‘process zone' that includes several interacting fractures in a small volume are required to initiate the unstable slip. Both processes require rupture of intact rocks, generate complex fracture geometry, and are associated with intense energy-release rate during slip. Recent observations and analyses are used to correlate rupture nucleation in laboratory tests with nucleation events of large earthquakes. It is proposed that earthquake nucleation occurs by the interaction among multiple fractures within a small volume that develops into unstable yielding of the healed fault zone.     

Research on distinguishing method and mechanism of tidal deformation anomalies before large earthquakes

Introduction There are many researches on modulating and triggering seismic activities by tidal force in China and abroad. Heaton (1975) studied the tidal triggering of seismic activity and discovered that the tidal stress did have an obvious triggering action on the dip-slip or oblique slip great earthquakes. Tidal triggering of earthquakes has been studied for a long time in China, especially in recent years. For example, LI et al (2001) provided the relationship between the solar and luna…     

Migration of historical earthquakes in California

Most large earthquakes of magnitude 6.0 in California during 1852–1987 appear to show a southeast-to-northwest tendency of epicenter migration. This finding is consistent with earlier findings ofSavage (1971) for a relatively few large earthquakes along the west coast of North America, and ofWood andAllen (1973) for smaller events along the San Andreas fault in central California. The average speed of migration is approximately 130 km/yr, which is within the range of speeds observed for other major seismic zones in the world. The epicenter migration in California may be the result of some small but broad-scaled episodic strain changes associated with creep waves induced by magma injections at the East Pacific Rise and propagating northwestwardly along a broad transform boundary between the Pacific and North American plates at subseismogenic depths as proposed bySavage (1971).     

数字化地形变资料异常形态与地震

针对近几年马陵山地震台的数字化地形变资料,参照台站仪器工作日志,排除了人为干扰、气象因素等台站已知干扰因素,通过综合分析总结了本台数字化地形变日值分钟值曲线在震前出现的几种异常图象.