A MATHEMATICAL SIMULATION OF EARTHQUAKE SEQUENCE IN NORTH CHINA IN THE LAST 700 YEARS

A scheme in Fig. l is used to simulate the earthquake sequence in North China in the last 700 years. With a postulated fault system, a mechanical parameter distribution and suitable boundary tractions, the stress field is computed by finite element method in plane strain. The fault zones are treated as elastic-perfectly plastic medium which flows according to Coulomb's criterion and its associated flow rule. An earthquake is simulated by lowering the static coefficient of friction to a kinetic one at the epicenter to cause a slip there and arrived at a new equilibrium position. The differences in displacement, stress, etc. before and after the lowering are considered to be due to the earthquake and compared to observations. After adjustments of parameters and boundary tractions, the results are satisfactorily compared with the major earthquake sequence of 14 events M_s≥7 and regions of seismic risk in the last 700 years. Possible localities of future earthquake risk after the Tangshan earthquake and ef     

SIMULATION OF THE SEISMIC TECTONIC STRESS FIELD IN NORTH CHINA

The paper reviews several methods of simulation used in this country to recover currenttectonic stress field related to earthquake occurrence in North China. The aim is to evaluatethe degree of seismic risk around Beijing area. The methods used are computational ormathematical simulation by the finite element method and experimental or physical simulationby the photoelastic method and the grid method. The results obtained by these methods arebriefly described. Most simulations indicate that Beijing is not a region of seismic risk.     

第18届国际理论与应用力学大会(ICTAM-18)

<正> 由国际理论与应用力学联合会(IUTAM)召开的4年一次的第18届国际理论与应用力学大会(ICTAM-18),于1992年8月22—28日在以色列海法市的以色列工业学院举行。大会选定的3个主题是:固体与结构力学中的不稳定性;海面力学与海气相互作用;生物力学。设置主题分会的目的是对力学中的某些重要领域做综合介绍,以强调这领域的重要性,或对新领域起提倡作用。     

有限长圆柱壳中轴对称弹性瞬态波

有限长的计及剪切变形和转动惯性的弹性圆柱壳的轴对称运动方程经过Laplace变换后转化为一组相空间中的方程。对该方程组作了一些适当的处理后,应用广义射线法,得到了相空间中位移和内力的射线法表达式。采用快速Fourier变换作Laplacl逆变换,即可得到圆柱壳受轴对称冲击载荷时的弹性瞬态波解。     

冲胀成型工艺的力学分析和实验研究

本文利用内部充液圆柱壳受轴向冲击塑性失稳的研究结果,提出了一种冲胀成型工艺并做了实验研究。结果说明这种工艺需要的设备简单、试件密封要求不高、模具强度和紧固力要求抵、成型变形比较均匀等优点,它适用于有应变强化的低强度材料的成型。     

动态焦散线实验方法及其在断裂力学中的应用

焦散线法是Manogg在1964年提出来的,现已发展成一个主要的断裂力学实验方法。国内近些年对焦散线法的兴趣也日益浓厚,但由于设备条件的限制,仍限于静态的断裂实验。本文研究了动态焦散线法在断裂力学中的     

弹塑性梁在轴向应力波下的动态屈曲

本文考虑轴向应力波效应，利用分叉理论研究各种支承半无限长弹塑性梁的动态屈曲问题。在轴向阶梯载荷和脉冲载荷冲击下得到了梁的临界屈曲载荷及初始屈曲模态。其结果与实验现象相一致。同时也为研究结构动态屈曲问题提供了有效途径。     

含参数的非线性方程组的数值解法

本文对含参数λ的非线性方程组f(α,λ)=O提出了在位移-载荷空间R~n+1中以弧长为参数追踪解曲线c(s)的弧长增量法,并统一地处理了搜寻极值点(extre-mum point)与分叉点(bifurcation point)的问题,我们将此法成功地用于弹性旋转薄壳的非线性分析。     

轴向应力波与弹塑性材料圆柱壳的动力屈曲

将弹塑性圆柱壳动力屈曲作为由于轴向应力波的传播而导致的分叉问题进行研究,找出该壳发生屈曲的机理,并讨论对各种支承的弹性和弹塑性壳在轴向阶梯载荷和脉冲载荷冲击下的屈曲问题.     

巷道大变形的粘性流体有限元分析

本文运用粘性流体有限元方法,计算软岩体中巷道围岩的速度场和应力场。通过调整边界面力以及各部份围岩的力学参数,使计算值与实测值相近,反演出围岩的粘性系数大约在10~5—10~6泊的范围内。