Cyclic strength and deformation of crushable carbonate sand

Cyclic triaxial tests have been carried out on a skeletal carbonate sand from the west coast of Eire. Results are presented for undrained cyclic shear tests on samples with 80% of relative density consolidated under both isotropic and anisotropic conditions. Failure was defined as a 5% double amplitude cyclic strain and a 5% peak axial strain for stress-reversal and non-reversal stress conditions, respectively. Using this definition the cyclic strength for isotropically consolidated samples was affected by the confining pressure although the angular platey nature of the sand resulted in higher cyclic strengths than for a comparable silica sand. For anisotropically consolidated samples the cyclic strength increased with increasing initial static shear stress while on the other hand the cyclic strength normalised in the usual way with respect to the initial confining pressure decreased as this pressure increased.     

Geometrical textures of faults，evolution of physical field and instability characteristics

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地震构造活动的模拟试验

本在活动构造考察及研究的基础上，采用先进的精密仪器仪表，在模拟试验中自控制监测构造活动情况，深入研究地震前后的断裂运行特征及其与地震的关系，这对圈定地震危险区和判定可能发生强震的破裂段，为国民经济建设提供可靠的依据，对逐步实现地震预报，最大限度地减轻地震灾害，均具有重要实际的意义     

甘肃中部集水观测试验研究

根据甘肃省中部的3年集水观测资料,分析了径流系数与集水面材料、坡度、雨强的关系,并结合甘肃河东地区19个气象站的自记降水资料,估算了平均径流系数及其均方差等,为集水技术在农业上的应用提供科学依据.     

初析静力触探判别液化对标准贯入试验的优越性

结合7个勘察场地的标准贯入和静力触探原位测试数据,应用数理统计原理和方法对二者进行比较分析,得出用静力触探试验判别地基土液化的均方差和变异系数等均优越于标准贯入试验。     

桩基瞬态动测响应的数学模型及基本特性

根据桩在瞬态激振方式下的阻尼波动方程,本文分别给出端承柱与浮承桩的振动初始条件和边界条件,并导出了两类桩瞬态动测响应的数学模型.通过与试验桩实测响应的对比,证明所建立的数学模型是正确的.文中还分析和讨论了桩的瞬态动测响应的五个基本特性,为动力测桩的参数估计提供了较严格的理论依据.     

岩石蠕变破坏实验研究及其对地震预报的意义

通过对不同温度和围压条件下济南辉长岩的蠕变破坏实验结果和声发射特征分析,本文提出以岩石蠕变破坏应变做为岩石蠕变破坏判据。建立了岩石蠕变破坏应变的经验关系式。依据实验结果得到相应的济南辉长岩蠕变破坏应变参数,进一步探讨了预报岩石蠕变破坏和地震的方法     

回归分析在震磁关系研究中的应用

通过相关分析北京、兰州、银川、红山地磁台地磁垂直分量Z(世界时13—14时)时均值资料(每两台相组合,以月为统计单位),得相关系数R和回归系数b。经统计检验,发现不同台站的R、b大小虽有差异,但正常情况下均在其置信区间变化(置信概率0.95)。几次中强震前,b、R大幅度下降,连续偏离其控制区间,至临震前1—2月或当月趋于恢复或完全恢复。对不同台组的垂直分量差ΔZ与时间作回归分析(ΔZ为时间t的函数),得不同台站的线性回归方程及相关系数R。正常情况下ΔZ在回归方程的置信区间变化(置信概率0.95),当地磁台附近孕育中强以上地震时,ΔZ明显偏离回归方程的控制区间。应用以上两种方法对80年代以来宁夏及其邻区的六次中强地震作了对应效果检验,并对发现的问题作了简略探讨。     

The experimental study of acoustic emission during creep of rocks

Under normal temperature, the creep experiments with complete samples of Gabbro and Marble rocks are made under uniaxial compression. It is found that at the instantaneous creeping stage, AE activities increase with loading; at the steady creeping stage, large AE signals may appear at lower background of AE action, andm—value which shows the relationship between AE amplitude and frequency keeps stable on the low value or decreases; at the accelerate creeping stage, AE activities increase andm—value decreases quickly or decreases again after recovery. These experimental results are related to the quality of the samples. In this paper, AE activities during three stages of creeping process are connected with the seismic patterns (for exampleb—value, foreshocks). Finally, it is pointed out the possibility that the foreshock—mainshock—aftershock earthquake sequence has been formed by the mechanism of creep fracture of crustal rocks. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 104–112, 1991. This subject is sponsored by the Chinese Joint Seismological Science Foundation.     

现代地壳应力场研究

本文简要介绍研究现代地壳应力场的途径,包括测震学、地应力测量、构造地质学、岩石有限应变测量和平衡剖面等方法。在内容方面强调历史分析。模拟实验的目的在于确定应力数据之间的内在联系和区域分布,以达到绘制一系列的应力图件。最后提出检验模拟实验结果的准确性和可靠性的三条判据。