Comparative research and its significance of deformation measurements by technologies of laser real-time holographic interferometry and radar differential interferometry

The principles and applications of laser real-time holographic interferometry （LRTHI） and radar differential interferometry （RDI） technologies are described in this paper, respectively. By using LRTHI, we can observe the deformation of samples under pressure in the lab and study the anomaly characteristics relating to different strain fields in different fracture-developing areas; while by using RDI, we can observe the landform and surface deformation. The results of deformation observed before and after the Ms=7.9 Mani earthquake （Tibet） and Ms=6.2 Shangyi-Zhangbei earthquake in China are obtained. It is pointed out that LRTHI and RDi are similar, which study the characteristics of anomalous deformation field by fringe variations for both of them. Therefore, the observation of deformation field in the seismogenic process, especially in the period impending an earthquake by RDI, and the comparative study in the lab by LRTHI are of great significance.     

A new method of testing pile using dynamic P-S-curve made by amplitude of wave train

Introduction To the impact pattern, the dynamic test with high strain is generally grouped into two kinds.One is stricken by hammer and another is by rocket. The former is widely used and the latter isused widely abroad and seldom used at home. To the analyzing method, it is also divided into twokinds. One is the method of wave equation and another is the method of experimental formula.The methods of Smith, Case and Capwap and other improved methods belong to the former, andthe methods …     

Experimental research on critical point hy- pothesis

Introduction Earthquake is a kind of severe natural disaster. In order to predict earthquake effectively, thegeoscientists at home and abroad have carried out a great deal of studies on seismicity. For exam-ple,Willis, (1924) and Tocher (1959) made some early investigations on seismicity before largeearthquake. Chinese geoscientists performed even more studies in this field (CHEN, et al, 1981;HUANG, FENG, 1981; LIU, 1982; LU, 1985; LU, et al, 2001; MA, et al, 1982; MEI, 1960; …     

态矢量方法的实验研究

在地震等灾变的发生之前，会出现一定的前兆现象。中通过实验方法对这些前兆现象之一的态矢量的异常变化进行了研究。实验使用声发射技术(Acoustic Emission)，对三轴应力条件下岩石试件内部微裂纹的产生和扩展进行了记录。实验结果表明在岩石试件最终破坏之前，表征态矢量的相关参量都发生了异常明显的变化，这表明态矢量的异常变化可以被用作为岩石等脆性材料灾变的前兆，使用态矢量方法可以对脆性材料的破坏乃至地震作出预测。     

曲靖电厂冷却塔桩位下浅层基岩内洞穴的震波勘探研究

以曲靖电厂冷却塔为例,叙述桩位下浅层基岩内的洞穴勘探方法.采用高频地震勘探仪系统,或在桩底原位激发、接受震波,或几个桩底联测,互为激发、接受震波,或将两者合并进行.通过对震波的震相、周期和振幅等特征的分析确定桩位下浅层基岩内是否存在洞穴.震波周期大,反射波到时早,则在浅层基岩内存在洞穴;而周期小,且无反射波者,在浅层基岩内没有洞穴.     

An experimental study of the dynamic features of shadow areas of caustics in response to loading/unloading fracture

IntroductionCHEN (1981), GENG, et al (1980), YAO (1981) and others have found out that different stress paths can lead to fracture. They have further studied the precursory features of wave velocity ratio, acoustic emission, and so on, in this situation. YIN (1987), YIN and YIN (1991), Yin, et al (1994, 1995, 2000) have put forward the concept of loading-unloading response ratio. When a mechanical test system is in a stable state, the path of its response to loading is the same as that…     

Y形块体交界处多点大破裂的模拟实验研究

采用有机玻璃试样,在其上用激光刻划出雁列式断层组成的Y形块体边界.用特殊加载方式,使夹在Y形上部中间的块体能相对于两边向下移动.用实时全息干涉计量方法(激光)、焦散阴影光学法和微破裂(声发射)信息采集分析技术研究块体交界处多点大破裂的特征.结果显示:随着加载,在切缝端点处的条纹逐步变密,进而形成有明显边界的阴影区.这些阴影区会随荷载增加变大,随卸载而减小.荷载再增大,相邻两切缝端点处的阴影区会连成一片.这些阴影区为强烈应变或应力集中区,即应变核或应力核.微破裂定位资料同时证实:阴影区达到足够大后会有破裂发生;并且先变大并达到额定值(如破裂强度)的阴影区先发生破裂.荷载再增大,多个阴影区先后达到额定值,以后,大破裂在各个阴影区交替发生.     

加载破裂和卸载破裂的焦散阴影区动态特征的实验研究

以实时全息干涉计量方法和焦散阴影光学法，用有机玻璃试样直观、形象地研究加载过程和卸载过程破裂时的应力（应变）场、塑性区或成核区（阴影区）不同地动态特征变化．结果发现，在低应力时，预制裂缝端点先出现应变核（条纹密集区），进而形成焦散阴影区．这些核和阴影区会随荷载增加变大，随卸载而减小．在一定的压力范围内重复加载卸载（循环加载），焦散阴影区则反复增大缩小；但在高应力时，尤其在将出现大破裂时，加载和卸载的焦散阴影区变化是不可逆的，其变化也完全不同．加载破裂时的焦散阴影区由慢到快迅速扩展；而卸载时的焦散阴影区则扩展较慢，并且在尖角形前方有一圆形阴影．      

含多组雁列构造试样的特征位移场与声发射的关系-应变空区的实验与理论探讨

针对唐山等大地震前出现的形变空区现象，依据实验和理论对应变空区进行了探讨． 实验过程中采用焦散线法、实时全息干涉计量方法(激光)图像摄影记录，同时进行微破裂(声发射)记录．依据固体损伤理论，结合微破裂定位对应变空区进行研究，得出两点结论:①应变空区在线弹性情况下出现是一种必然现象，且应变空区的位置相对稳定，与裂纹端部的应力集中相对应；②应变空区内几乎不发生微破裂．微破裂总是从高应力区产生，且几乎就发生在应力集中区与应变空区相联的条带内，最终表现为微破裂(声发射)的带状或成丛分布．主破裂总是从应变核(焦散阴影区)开始，然后向应变空区急剧发展，形成主大破裂，最终导致试样崩溃．      

利用Rayleigh波反演浅土层的剪切波速度结构

根据均匀半空间Rayleigh波相速度与介质剪切波速度之间的关系,对某一频率面波的影响深度内各层介质进行"均匀"化,使其等效于均匀半空间．并利用模型进行正演,以确定在这种均匀化的前提下,面波勘探深度与波长的关系．应用相匹配滤波技术从实测面波信号中分离出基阶Rayleigh波信号,对它进行多重滤波和叠加处理,精确地计算出5．0-30．0Hz之间的基阶面波相、群速度频散．使用"均匀"化的方法,从相速度频散曲线中获得反演的初始模型,利用群速度频散反演得到35m以上各土层的剪切波速度结构．结果表明,反演结果与钻孔资料较为吻合