公转轴应力场星球说——地球、火星南南西应力场四组三维构造系

介绍了对地球构造格局,运动方式及其动力源问题研究取得的新成果。它不同于流行已久的以地球自转轴旋转和以软流圈带动岩石圈漂移以及随机的地幔柱（流）为构造动力源的观点,而是与黄赤交角相关的沿公转轴方向的统一应力场,认为中国西部ＮＷＷ向压性,ＮＥＥ与ＮＮＷ是与黄赤交角相关的沿公转轴方向的统一应力场。认为中国西部ＮＷＷ向压性,ＮＥＥ与ＮＮＷ向两组共轭扭性及ＮＮＥ向张性带交接,为来自全球ＳＳＷ主压应力场形成的     

Stress Field Estimations for Colima Volcano, Mexico, Based on Seismic Data

 For first time, during 1991, seismic activity was recorded during an eruption at Colima volcano. We analyze these data to obtain a stress pattern using a composite focal mechanism technique. From the analysis of regional seismicity, the Tamazula Fault and the Armeria River appear as active features and the dip of the slab east of the Jalisco Block is approximately 12°. Southwest of Colima volcano a vertical alignment of seismic events was observed. We estimate five different composite focal mechanism solutions from our data set, which indicate a change of the stress field at the volcano after the 1991 eruption. These solutions suggest that the stress field in the volcanic edifice was controlled by stresses related to the emplacement of magma superimposed on the regional stress field. No evidence of active local faults in the volcanic edifice was found. We propose a model for the eruptive process that involves tilting of the volcanic edifice. Received: 15 October 1995 / Accepted: 26 October 1998     

煤矿矿震应力窗口效应

对煤矿矿震活动特征,震源机制解,与天然地震的相关性以及特殊的环境条件等进行了研究,认为煤矿矿震的孕育和发生受控于区域应力场,具有区域应力变化的灵敏窗口效应,可视为探索天然地震前兆和区域应力场变化的应力窗口。     

北部湾6.1,6.2级地震序列的环境应力场

应用Ｐ波初动半周期直接测定环境剪应力值的方法,测定了北部湾６．１,６．２级地震前后中小地震的环境剪应力值τ０,由此分析了北部湾地震过程的环境应力场特征。结果表明,北部湾６．１级地震后平均剪应力值较高,达１８ＭＰａ左右;６．２级地震及两次５级余震后剪应力值下降很快,降至目前的６ＭＰａ左右。在此基础上对北部湾地震活动趋势作了初步分析。     

Stress–strain behaviour of a loosely compacted volcanic-derived soil and its significance to rainfall-induced fill slope failures

The stress–strain behaviour of a soil is crucial to the recognition of the mechanism of slope failure. Triaxial tests, composed of isotropically consolidated drained (ICD) and undrained compression (ICU) tests and anisotropically consolidated constant deviatoric stress path (CQD) tests, were carried out with the aim of investigating the stress–strain behaviour of loosely compacted volcanic-derived soils. The fact that the critical states are the same for ICU, ICD and CQD tests may show that the critical state is independent of the above three stress paths. The critical state line, as defined in critical state soil mechanics, is obtained from the e–log p′ and q–p′ plots based on the results of the above tests. The initial state of the consolidated specimens at initiation of failure may be classified as dilative or contractive in the light of the locations of the soil state relative to the critical state line. For contractional soils, the increased pore water pressure generated by rainfall infiltration leads to a contractive failure in a drained manner, giving rise to high excess pore water pressure. The excess pore water pressure caused by contraction cannot be dissipated instantly, resulting in a decrease in the shear resistance of the soil. The failure process is rapid. The failed soil mass is prone to flow after failure under the action of gravity due to its high moisture content and inflow of surface runoff and rainwater. For dilational soils, the increased pore water pressure resulting from infiltration leads to dilation, which reduces pore water pressure and thus increases the shear resistance of the soil. However, continued rainfall infiltration may be able to equilibrate the reduction in pore water pressure caused by dilation and, therefore, the dilation or displacement can continue. In Hong Kong, volcanic-derived soil is characterized by high permeability. Both the high permeability of volcanic-derived soil and a shallow failure surface make it possible for the reduction in pore pressure to equilibrate relatively quickly. Therefore, the failure is also rapid, at least for poorly compacted fill slopes.     

单轴压缩下大理岩的Q值与频率关系的研究

实验采用单轴压缩循环加载方式,在地震频段内测量了莱阳大理岩的品质因数Q值.在频率为0.1-10 Hz范围内,Q值随频率变化是非线性的,而且在5 Hz附近出现峰值.用正弦波和用三角波两种方式加载所获得的Q值与频率关系很相似,并且三角波加载所测得的Q值普遍高于用正弦波加载测得的Q值.疲劳试验结果表明,正弦波循环加载大大降低了岩石的强度,三角波则对岩石强度降低较少.     

利用FG5绝对重力仪观测数据确定重力垂直梯度

本文建立了利用FG5实测数据求解重力垂直梯度的数据处理模型与算法.通过对多次自由落体实验的下落距离拟合残差叠加求均值,发现下落距离观测量中存在明显的有色噪声.通过对有色噪声的建模,并以剩余残差为依据选取可靠的下落时段,解算测站点的重力垂直梯度.利用本文所提出的数据处理方法分别对FG5-214绝对重力仪在两个测站上的观测数据进行处理,以相对重力仪测量的重力垂直梯度结果为参考值,本文处理得到的重力垂直梯度结果相比于未考虑有色噪声并依据经验选取下落时段的解算方法得到了显著改善.     

COMPREHENSIVE ANALYSIS OF THE MACRO- AND MICRO-PHYSICAL CHARACTERISTICS OF DENSE FOG IN THE AREA SOUTH OF THE NANLING MOUNTAINS

Using the composite field observational data collected in the area south of the Nanling Mts. and numerical modeling, the seasonal features of dense fog and visibility, fog drop spectrum and physical concept of fog forming have been analyzed. The occurring frequency of low visibility（≤200 m） is very high with a mean of 24.7%, a maximum of 41.8% from the end of autumn to winter and next spring. The fog processes that occur in the area south of the Nanling Mts. in spring and winter result from the interactions of complicated micro-physical processes, the local terrain, water vapor transportation and the influencing weather system. The fog processes are arisen from advection or windward slope, which is much different from the radiation fog. Cooling condensation due to the air lifted by the local mountain plays an important role in fog formation. Windward slope of the mountain is favorable to the fog formation. Dense fog can occur at lower altitudes in the windward slope of mountain, resulting in the lower visibility. The fog is mainly of small-drop spectrum with smaller number-density than that of urban fog, and its drop spectrum has descending trend in the section of smaller diameter. The inverse relationship between fog water content and visibility is the best among several relationships of micro-variables. In addition to micro-physical processes of fog body itself, the motion of irregular climbing and crossing over hillside while the fog body is being transported by the wind are also important reasons for the fluctuation of micro-physical parameters such as fog water content.     

汶川地震科学钻探3号井孔附近微震震源参数确定及其意义

基于微震监测仪器频带及波形记录的时频特征,我们筛选出汶川地震科学钻探3号井孔周围微震台阵2012年记录的218个t_s-t_p1 s的微震.通过盖戈法与和达法相结合确定微震震源的几何参数,发现这些微震分布大体呈NE-SW展布,与龙门山断裂带的走向基本一致.无论是采用《地震台站观测规范》中的量规函数(量规函数GF)还是李学政等(2003)的量规函数(量规函数LXZ),近震震级均与矩震级呈现出较好的线性关系,向震级小的一端延伸时都表现为M_LM_W,但采用李学政等的量规函数时该趋势更加明显.同时采用Brune和Boatwright震源谱衰减模型对观测震源谱的拟合表明拐角频率具有模型依赖性:基于Brune模型拟合得到的拐角频率大于基于Boatwright模型得到的拐角频率.无论基于哪一种模型,矩震级与拐角频率、破裂半径的对数线性关系均较弱,与应力降、视应力的对数则存在较好的线性关系.这些关系不支持应力降、折合能量、视应力为常数的观点,表明微震与大地震的震源物理过程存在差异.视应力与应力降成比例,比例系数小于0.5,表明破裂动力学模式符合SavageWood模式.近震震级与矩震级拟合关系Mw=a+bM_L中b的大小与应力降和地震矩的关系有关,△σ∝M_0~γ,则b=1/(1+γ),因此从b的大小可以粗略地判断应力降与地震矩的关系.本文对应于γ≈1的情况,与基于量规函数LXZ得到的近震震级与矩震级关系中系数b=0.53吻合,这说明仅从辐射能量的角度考虑量规函数LXZ较量规函数GF准确.     

地震的应变张量观测与应用前景

地震发生时的动态应变场,在研究地震触发、地震破裂、地面破坏、水文和岩浆变化等方面都具有重要应用意义.地震的应变张量观测和现有的惯性地震仪观测的物理量不同.前者可以直接记录到地震发生时震源辐射的应变(应力)波,而后者记录到的是位移、速度或加速度.地震频率的应变测量在地震学中的应用前景主要表现在:①测量震源机制解理论预言的辐射4象限分布;②测量库仑应力变化;③换算成动态应力以评估地震烈度;④测量地震波的能量密度;⑤测量地震断层形变加速和形变局部化过程.用惯性地震仪的记录虽然在理论上也可以解算出动态应变值,然而种种原因导致计算结果的误差很大,往往不可接受.应变张量地震仪若能与现有的惯性地震仪配套起来,形成大规模台阵,则有可能推动应变地震学的诞生,在地震观测和地震学科领域引起重大革新.