地震波模型試驗仪器的电子线路

本文討論了一套配合現成示波器进行地震波模型試驗用的电子线路。綫路的前置放大器的通頻带为2—700千周,增益为60分貝,輸入端短路噪声电压为2.5微伏.高压脉冲发生器产生一个寬度为2—33微秒的幅度为500伏的矩形电脉冲。时标电路产生2,10,50微秒三組吋标,基本吋标（2微秒）可由稳定的石英振蕩器随时加以校准。整个线路此較簡单、灵活,一般地球物理实驗室試制容易,且可根据具体要求加以变动。     

二維弹性波模型試驗

一、引言只有在少数比較簡单的介貭結构中,弹性波的传播問題可以自理論上予以解答;实际中所遇到的問題,往往要复杂得多。卽使是最簡单的問題,理論的計算也常常很繁复。因此如何利用簡便的模型来解决弹性波的传播問題,是很多人所感到兴趣的。     

非均质矿体地震模型的衍射、转换波及次生波研究

采用超声地震模型、数学模型正演试验和矿井试验观测研究了１＜ｋα＜１０范围非均质体散射波场中,衍射波和转换波的运动学和动力学特征．上述方法获得了一致的结果．研究中发现一种次生震源及次生波,其在今后地震勘探中可能有一定的应用价值．     

层状地壳模型地面地下记录地震波的理论地震图和频谱计算

本文首先发展了计算层状介质地面及地下记录地震波理论地震图的部分分离变量—有限差分计算方法,其最主要的环节是引进了吸收边界条件,使计算工作量大大减少,得以在实际工作中推广应用。其次,应用矩阵方法计算地面及地下记录的地震波的理论频谱。最后给出了用上述方法得到的华北地区两种不同的理论地壳模型情况下的理论地震图和频谱计算结果。应用这些理论结果,可根据实际地震观测资料对地壳介质模型进行分析、评判和优选。     

二維弹性波模型試驗

一、引言只有在少数比較簡单的介貭結构中,弹性波的传播問題可以自理論上予以解答;实际中所遇到的問題,往往要复杂得多。卽使是最簡单的問題,理論的計算也常常很繁复。因此如何利用簡便的模型来解决弹性波的传播問題,是很多人所感到兴趣的。     

AN ANALYTICAL HYSTERESIS MODEL FOR ELASTOMERIC SEISMIC ISOLATION BEARINGS

For the purpose of accurately predicting the seismic response of base-isolated structures, an analytical hysteresis model for elastomeric seismic isolation bearings is proposed. An extensive series of experimental tests of four types of seismic isolation bearings—two types of high-damping rubber bearings, one type of lead-rubber bearing and one type of silicon rubber bearing—was carried out with the objective of fully identifying their mechanical characteristics. The proposed model is capable of well-predicting the mechanical properties of each type of elastomeric bearing into the large strain range. Earthquake simulator tests were also conducted after the loading tests of the individual bearings. In order to show the validity of the proposed model, non-linear dynamic analyses were conducted to simulate the earthquake simulator test results. Good agreement between the experimental and analytical results shows that the model can be an effective numerical tool to predict not only the peak response value but also the force–displacement relationship of the isolators and floor response spectra for isolated structures. © 1997 by John Wiley & Sons, Ltd.     

AN INTERACTION MODEL FOR ELASTIC WAVE PROPAGATION IN TWO-PHASE MEDIA*

The effect of interactions among spherical inclusions on the effective propagation of long wavelength elastic waves in a two-phase medium is investigated theoretically. Interactions are taken into account in an average sense via a generalized self-consistent scheme. Bounds on the effective elastic moduli are obtained by overestimating and neglecting contributions of neighbouring inclusions. An intermediate model is proposed, which introduces the effect of interactions into the effective properties without requiring more information about the geometry of the medium than the relative volumes of the constituents.     

ELECTRONIC ACCELERATION-SENSITIVE GEOPHONE FOR SEISMIC PROSPECTING***

Previously ignored characteristics of the seismic recording instrument are presently experienced as limitations as more sophisticated interpretive methods using wider frequency ranges are developed to extract stratigraphic information from seismic land data for hydrocarbon and mineral exploration. Most of these limitations arise from inadequate characteristics of the first element of the seismic instrument: the geophone. A geophone does not faithfully follow the motion of the earth for higher frequencies due to poor geophone-earth coupling. This filtering effect brings about time shifts that are dependent on the frequency and the soil type. A geophone can also produce spurious outputs, brought about by the motion of the suspended part of the geophone, with a magnitude comparable to that of the desired output. The suspension is made very compliant to obtain the required sensitivity. A compliant suspension, however, gives a large sag. The geophone can therefore only be used in one position, tolerating little tilt. A compliant suspension also widens the traveling range of the movable part. Minor sensitivity changes with travel are then noticeable as nonlinearity, since the surface wave is large with respect to the reflected wave. A compliant suspension is usually realized in the form of thin, spirally shaped spring-spiders. Such suspensions exhibit transverse or rotational resonances that are in or close to the seismic frequency band. Excited by ground roll, they can produce considerable undesirable output. The novel geophone we describe is a light-weight (17 g) acceleration-sensitive transducer which gives good ground coupling and partial correction for the increasing damping in the earth with increasing frequencies. It employs internal hybrid electronics for a magnetodynamic velocity-nulling feedback system. Velocity nulling makes the movable part of the geophone virtually rigid with respect to the housing. This makes the geophone characteristics independent of the suspension. The springs used are stiff in a transverse and rotational direction so that the suspension resonances are well outside the useful frequency band. This suspension also allows the geophone to be used in any orientation while being only sensitive to the vibration component along the main axis. The feedback system makes the sensitivity flat within 1 dB from 2 Hz to 500 Hz, with a phase tolerance smaller than 5°. The geophone is robust, has no moving internal wires, employs a current output [sensitivity 1 mA/(m s^?2)] and internal gain so that the signal-to-cable-noise ratio is improved. This type of output allows parallel connection without any interaction between the geophones.     

二维地震波模型试验的振源

本文討論二維模型試驗所用的二种振源:扩张中心型的振源和垂直集中力型的振源。扩张中心型的振源系用压电钛酸鋇短柱体的径向伸縮,以柱面为发射面而得到的。实驗証明,柱面上的伸縮主要是由直径决定的单頻振动。因此,用寬度相应于径向振动周期的矩形电脉冲来激发晶体时,可以消除由晶体自由振动所造成的“余震”,从而得到短暫的声脉冲。单力型振源是一个用钛酸鋇晶体和黄銅棒制成的杆状发射器。这种发射器在工作頻率范围內,实际上是一个非周期性器件,因此不存在器件的自由振动問題。在实驗中研究了三种不同直径杆状发射器的发射强度与波形同发射方向角间的关系。     

二维地震波模型试验的振源

本文討論二維模型試驗所用的二种振源:扩张中心型的振源和垂直集中力型的振源。扩张中心型的振源系用压电钛酸鋇短柱体的径向伸縮,以柱面为发射面而得到的。实驗証明,柱面上的伸縮主要是由直径决定的单頻振动。因此,用寬度相应于径向振动周期的矩形电脉冲来激发晶体时,可以消除由晶体自由振动所造成的“余震”,从而得到短暫的声脉冲。单力型振源是一个用钛酸鋇晶体和黄銅棒制成的杆状发射器。这种发射器在工作頻率范围內,实际上是一个非周期性器件,因此不存在器件的自由振动問題。在实驗中研究了三种不同直径杆状发射器的发射强度与波形同发射方向角间的关系。     

短波电台对地震仪干扰机理分析及抑制方法

对短波电台发射时干扰地震仪的机理进行了分析。指出干扰形式及干扰噪声进入地震仪的端口，用抗干扰三要素理论结合地震台、站实际条件，采用低通网络抑制干扰，收到了明显的效果