陕南膨胀土及其滑坡灾害研究

膨胀土在陕南汉江流域的汉中盆地、西乡盆地及安康盆地分布广泛，其面积约达1300km2，占汉江流域中3个盆地面积的1/2以上. 由于膨胀土土体的胀缩变形和土体结构变异，导致滑坡灾害广泛发育，致使工程建筑和农田破坏，给国家和人民造成了巨大的经济损失，因此，研究陕南膨胀土及其滑坡灾害，不论在理论和实践等方面，对陕南的经济建设都具有十分重要的意义.     

软土后生作用的探讨

讨论了软土地区的褐黄色硬壳层、暗绿色硬土层和所谓“次生硬土”等特殊土层的成因,提出后生作用对软土改造的观点。这类土往往是建构筑物的天然地基或桩基持力层,因此进一步搞清其成因变化将是研究土力学和工程特性的重要地质学基础。     

膨胀土作为桩基持力层的实验研究

根据对邯郸膨胀土中桩基的实验研究,认为膨胀土具有一定埋深时,可作为良好的桩基持力层;通过3种桩型应用情况的分析比较,论证了扩底桩是膨胀土持力层上理想的桩基形式。     

农田尺度土壤水分的监测

根据田间试验实测资料分析了田间土壤水分的空间变化特征和时间动态变化,探索了监测农田水分变化时如何确定其合理的取样数目,讨论了农田尺度的土壤水分应如何监测,为节水灌溉,提高田间用水管理水平提供科学依据。     

用改进的时间差分有限分析法模拟地下水非稳定井流方程

提出了一种改进的时间差分有限分析算法,它能够避免在求解水头剧烈变化时用一般有限分析法计算精度较差的缺陷.算法的稳定性好.     

株州市土壤重金属污染的对应分析

株州市土壤重金属污染的主要原因是工厂排放有害气体，或是水体污染物随灌溉进入土壤。采用对应分析方法，将市区土壤重金属污染分析３种类型。靠近人业污染源附近，镉的含量及污染指数高；大部分土壤受多种重金属污染；水稻土主要表现为铅的污染。     

第一类算子方程的吉洪诺夫正则解的收敛性和渐近阶估计

本文对于第一类算子方程当右端近似给定和当算子与右端皆近似分别给定时,讨论如何确定正则参数。并给出吉洪诺夫正则解的收敛性和渐近阶估计。     

Triggered earthquakes and deep well activities

Earthquakes can be triggered by any significant perturbation of the hydrologic regime. In areas where potentially active faults are already close to failure, the increased pore pressure resulting from fluid injection, or, alternatively, the massive extraction of fluid or gas, can induce sufficient stress and/or strain changes that, with time, can lead to sudden catastrophic failure in a major earthquake. Injection-induced earthquakes typically result from the reduction in frictional strength along preexisting, nearby faults caused by the increased formation fluid pressure. Earthquakes associated with production appear to respond to more complex mechanisms of subsidence, crustal unloading, and poroelastic changes in response to applied strains induced by the massive withdrawal of subsurface material. As each of these different types of triggered events can occur up to several years after well activities have begun (or even several years after all well activities have stopped), this suggests that the actual triggering process may be a very complex combination of effects, particularly if both fluid extraction and injection have taken place locally. To date, more than thirty cases of earthquakes triggered by well activities can be documented throughout the United States and Canada. Based on these case histories, it is evident that, owing to preexisting stress conditions in the upper crust, certain areas tend to have higher probabilities of exhibiting such induced seismicity.     

Moment tensor inversion of some aftershocks of the April 18, 1985 Luquan earthquake of Yunnan Province, China

Based on the three component accelerograms, recorded at near-field distance by a temporary seismic network consisting of digital cassette tape recording accelerographs, the focal mechanisms of three aftershocks of the April 18, 1985, Luquan, Yunnan Province, China, earthquake ofM _S=6.1, are calculated using seismic moment tensor inversion technique. The phases of direct P, S and converted SP waves in the displacement seismograms, produced by twice integrations of the observed accelerograms, are identified via forward calculation using Green’s functions for homogeneous semi-infinite elastic medium, and used in the inversion. The results of inversion show that a better fit of synthetic to the observed seismograms of direct as well as converted phases can be achieved if appropriate weighting functions are used in solving the over definite linear equations. While these aftershocks are of different magnitudes (M _L=4.8, 3.2 and 3.5, respectively) and hypocentral locations, their focal mechanisms are very similar and consistent with that of the main shock. This feature demonstrates the intrinsic correlation between the occurrence of aftershocks and the seismogenic fault of main shock. Our experimentations show that using the near field accelerogram obtained from the digital seismic network with appropriate azimuthal coverage on the focal sphere, with the aid of even simple medium model, not only the shear dislocation source, but also the isotropic part and CLVD (compensated linear vector dipole) can be retrieved by the technique of moment tensor inversion. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 412–419, 1991. This work is supported by the Chinese Joint Seismological Sciences Foundation and the Western Yunnan Earthquake Prediction Test Site (WYEPTS), State Seismological Bureau.