中国的三种体积式应变仪

第一次对外报导了中国的三种体积式应变仪的进展情况。第一种为Sacks——Evertson型钻孔应变仪,文中介绍了中国制造的这种仪器的参数和工作特性,举出了几个震前异常的例子;第二种为“液压型”体积式应变仪。它由一只小型液压差传感器取代了原Sachs仪器中的核心元件:位移传感器、波纹管和小孔滤波装置改装而成。这种改进一方面使仪器的长度缩短,便于制作、运输和下井安装,另一方面提高了仪器的高频特性和抗震、抗过载的能力;第三种为刚研制成功的全固体化动态应变计,利用大型PZT压电陶瓷嵌入不锈钢筒中,能获得足够高的动态应变灵敏度和较宽的频带,能在较深的钻孔中工作,使用灵活,对短临前兆的观测及同震应变阶跃、应变地震波、地脉动等现象的观测研究有一定意义。     

中国台湾以东地区地震矩张量研究及其构造意义

本文利用长周期Ｐ波波形反演方法，推断了１９８６年１０月至１９９１年期间发生在中国台湾岛东部及其附近海域中８次中强地震的矩张量．矩张量解揭示了发生在这一区域边界处的地震震源性质的规律性变化：沿西部边界的主旋错动，沿北部边界的右旋错动，西北角花莲地区的逆冲断错及显著的体积收缩分量．这一结果表明，台湾地区是菲律宾海板块与欧洲大陆板块边界中的一特殊地段，海洋板块的俯冲在这里受阻．随着菲律宾海板块向西北方向的相对运动，在花莲地区发生了强烈碰撞．     

Modeling surficial sand and gravel deposits

Mineral-deposit models are an integral part of quantitative mineral-resource assessment. As the focus of mineral-deposit modeling has moved from metals to industrial minerals, procedure has been modified and may be sufficient to model surficial sand and gravel deposits. Sand and gravel models are needed to assess resource-supply analyses for planning future development and renewal of infrastructure. Successful modeling of sand and gravel deposits must address (1) deposit volumes and geometries, (2) sizes of fragments within the deposits, (3) physical characteristics of the material, and (4) chemical composition and chemical reactivity of the material. Several models of sand and gravel volumes and geometries have been prepared and suggest the following: Sand and gravel deposits in alluvial fans have a median volume of 35 million m³. Deposits in all other geologic settings have a median volume of 5.4 million m³, a median area of 120 ha, and a median thickness of 4 m. The area of a sand and gravel deposit can be predicted from volume using a regression model (log [area (ha)] =1.47+0.79 log [volume (million m³)]). In similar fashion, the volume of a sand and gravel deposit can be predicted from area using the regression (log [volume (million m³)]=–1.45+1.07 log [area (ha)]). Classifying deposits by fragment size can be done using models of the percentage of sand, gravel, and silt within deposits. A classification scheme based on fragment size is sufficiently general to be applied anywhere.     

体极化介质激发极化法理论研究

本文首先根据实验结果和对体极化介质激发极化机理的分析,并由极化率的定义出发,采用与以往不同的方法,提出等效电阻率概念。其次,根据位场的叠加原理,给出在稳定电流场中二次极化场欧姆定律的微分形式。然后,根据电量不灭定律,提出稳定电流场中二次极化电流密度法向分量连续的边界条件式。最后,给出几种典型条件下的理论计算结果。     

库尔勒台钻孔应变台址勘选

"十五"期间计划在库尔勒新建钻孔体应变观测点,依据规范和地质构造背景的调查,对6个预选台进行了对比分析,认为铁门关老台站的环境基本符合要求,对铁门关水库和孔雀河可能产生的影响作了一定的评估,认为不会对应变观测产生很大影响.     

Study on Volume Strain Inversion from Water Level Change of Well-aquifer Systems

Based on linear poroelasfic and hydrogeology theory, a mathenmatical expression describing the relationship between water level clmnge and aquifer volume strain is put forward. Combined with earth tidal theory, we analyze the response characteristics from well-aquifer water level change to earth tide of volume strain and present a method of volume strain inversion from water level clmnge. Comparing the results of inversion with real observed data, we found that there is a good consistency. This suggests that the method of volume strain inversion from water level clmnge is proper. It will offer a reference for learning about hydrogeology characteristics, volume strain and searching for precursor anomalies.     

Scouring of a granular bed by dam break: Experimental study and numerical simulation by a VOF-LPT coupling

The first part of the research reported here consists of an experimental campaign to study the scouring of a granular bed(glass beads, sand) induced by a dam break in an open channel. Two configurations are considered: with and without cylinders. In the second part of this study, the volume of fluid method coupled with the shear stress transport turbulent model and the lagrangian particle tracking method is used to simulate the local scour processes. The four-way coupling is realized by consider...     

北印度洋半日潮波的数值模拟研究

基于FVCOM(Finite Volume Coast and Ocean Model)模型,建立北印度洋海域(31^°~102^°E,16^°S~31^°N)的M₂和S₂分潮潮波数值模式,研究北印度洋半日潮潮汐、潮流分布特征。对底摩擦系数进行数值试验,利用代价函数梯度下降法,得到分潮调和常数向量均方根偏差(RMSE)的变化曲线,逼近并确定最优的底摩擦系数。将采用该系数的模拟结果与TOPEX/Poseidon卫星高度计交叉点的调和常数数据、国际海道测量组织(IHO)及部分文献中的验潮站数据进行比较与验证,一致性较好。其中对比卫星数据的振幅偏差为2~4 cm、迟角偏差为7^°~8^°,与验潮站数据的振幅偏差为3~6 cm、迟角偏差为8^°~9^°。根据模拟结果,分析了北印度洋海域M₂和S₂分潮潮波传播特征和潮流椭圆的空间分布特征等。M₂分潮潮波在阿拉伯海南部有1个无潮点,在波斯湾内有2个无潮点,最大振幅超过80 cm;潮流在西北印度洋和孟加拉湾中部大多为顺时针旋转,其余海域大多为逆时针旋转;流速在阿拉伯海东北部、安达曼海、波斯湾和孟加拉湾北部较大,最大流速为160 cm/s,其他海域较小。S₂分潮的潮波传播特征、无潮点的位置和潮流椭圆的空间分布特征等都与M₂分潮类似,但潮波振幅和潮流流速等都相对M₂分潮较小。研究完善了北印度洋海域2个主要半日分潮M₂和S₂的整体特征。     

非达西渗流拟启动压力梯度推算

岩体启动压力梯度的大小是石油开采,工程防渗处理等方面需要考虑的影响因素。非线性渗流现象已被广泛所认同,低渗透性岩渗流存在启动压力梯度,它基本代表了流体产生渗流时的压力梯度大小。试验对试样进水端水压进行长期稳定控制,出水端采用精确测定流出水体积变化量的方法进行流量测定; 当渗出端水体积的变化量与时间呈直线关系时,即认为该时段渗透特征符合达西定律。通过对具有不同渗透性的软弱岩系统的试验测试,根据实测渗透系数与压力梯度的正相关关系,提出了拟启动压力梯度推算的三次平均法,即:首先统一调整实测渗透系数值,然后确定绝对渗透系数值,再根据该值确定V0值, 3次取平均推算拟启动压力梯度的方法。分析表明:拟启动压力梯度随围压升高而增大,随岩石的绝对渗透系数降低而增大; 在渗透压差增大过程测得的拟启动压力梯度大于降低过程的拟启动压力梯度,这些都与理论分析结果相吻合。实例说明拟启动压力梯度推算三次平均法较为合理,易于推广使用。这为通过室内试验确定工程岩体启动渗流压力梯度的大小,提出了一种新的思路。