加载频率对铅合金减震器动力特性的影响

铅合金减震器是一种适用于电瓷型电气设备的新型减震器,其动力特性对减震效果有重要影响.根据断路器等电气设备的特点,定制了相应的铅合金减震器.通过铅合金减震器滞回特性试验,研究了加载频率对其动力特性的影响.同时以不同加载频率下得到的骨架曲线作为材料的本构关系,研究了加载频率对单自由度体系弹塑性地震反应的影响.研究表明:在相同输入下,采用不同本构关系的单自由度体系,其相对位移峰值、永久位移及塑性耗能均有较大差异,应重视加载频率对铅合金减震器动力特性的影响.     

Undrained behavior of natural marine clay under cyclic loading

To study the undrained behavior of natural marine clay under cyclic loading, two kinds of stress-controlled cyclic triaxial tests were conducted on natural K₀-consolidated Wenzhou clay. In the Series I tests, samples were cyclically sheared until failure, and the accumulative behavior was studied; based on the results, a suitable cyclic failure criterion is suggested for natural clays. The effect of loading frequency was also investigated, and it was observed that the loading duration t is a key factor in controlling the undrained cyclic behavior. In the Series II tests, cyclic undrained tests followed by strain-controlled monotonic compression tests were carried out, and special attention was given to changes in the undrained strength after cyclic loading. The degradation of the post-cyclic peak strength was affected by the accumulative behavior during cyclic shearing, but the deviatoric stresses at the critical state were nearly constant. Finally, the accumulative behavior of natural clays was simulated using a proposed anisotropic elastic viscoplastic model with a pseudo-static method of equivalent undrained creep, and the results indicate that this equivalent creep simplification is suitable in practice. By taking the apparent overconsolidation after cyclic loading into account, the post-cyclic strength degradation can also be explained by this model.     

共和地区四次5.5级以上地震前后的Y值变化

研究了青海共和7．0级地震前后孕震区域加卸载响应比的时间变化特征。Y值在7．0级主震之前异常明显。主震之后Y值的异常变化可用来预报近期强余震。     

Water Quality and Phosphorus Budget of Mogan Lake,Turkey

Mogan Lake is the largest recreational area near Ankara, which is the capital city of Turkey. Increased macrophyte growth in the water body and the present levels of urban development within the catchment are reflected in declining water quality and aesthetic deterioation. A study of the water quality of the lake was undertaken to quantify the variation of phosphorus, nitrogen, and chlorophyll-a concentrations during ice-free seasons from 1992 to 1994. Its total phosphorus and chlorophyll-a concentrations indicate a meso-eutrophic status. The total phosphorus budget of Mogan Lake was measured for a period of 22 months. The estimation of nutrient loading using Dillon-Rigler nutrient budget shows that an artificial load caused too high phosphorus inputs. The management implications of phosphorus loading and budget are discussed.     

青海祁连克克里5.1级地震的主应变比分析

利用祁连县地应变观测资料，对１９９２年６月青海祁连克克里５．１级地震信息进行了综合分析，提出了主应变比异常理论，在该理论的基础上探讨了该次地震的发震机制，同时分析了祁连建站以来的地应变观测资料，认为肃南～祁连断裂段上及附近发生的地震具有相似性，是在变化的附加引张应力场作用下，载荷弱化，促使正断层或正走滑断层易于活动所导致的。     

辽阳市区软土的工程地质特征

辽阳市区地表浅部呈透镜状断续分布的松软土体———淤泥质粉质粘土为静水或缓慢流水环境沉积,经生物化学作用而形成的。本文对其分布、形成、物质结构及工程地质特性进行了较系统的描述。并依据大量现场测试及室内土工试验成果,分析论述了该层软土天然独特的含水量高,孔隙比大,强度低,压缩性高,具触变性及承载力低的工程地质特性对勘察施工及建筑物稳定性的不良影响,提出了避让、挖除、选择合适桩型等科学合理的工程处理建议。     

桩基静载试验与高应变对比分析

桩基承载力对桩基抗震性能有很大影响。通过对大量的桩基静载荷试验和同一根桩上的高应变的对比研究，总结了高应变测试极限承载力的准确性与可靠性，分析了引起高应变测试结果误差的原因，提出了消除高应变测试误差的一些方法和注意事项。     

具有孔边裂纹的岩石厚壁筒试件的破裂特征

用五种应力途径对由五种岩石制备的孔边有予裂纹的厚壁筒试件进行实验,研究上述条件下岩石的破裂特征。结果表明:对含径向并贯穿轴向裂纹的试件,其破裂沿裂纹方向,为典型的张开型破裂;含与定直径成45°角并贯穿轴向裂纹的试件,破裂亦呈张开型,其裂面始于裂纹前缘,但却折转约45°角与定直径近于平行;中心含与轴向成45°角的椭圆裂纹试件的破裂,仍沿裂纹面方向,为张开型与滑开型的复合破裂。     

不同加载方式下路堤沉降性状与预测模型研究

从考虑土体流变的本构关系出发 ,证明了瞬时加载、线性或者近似线性加载和分级加载情况下路堤沉降的性状 ,提出了从数学上能满足各自变形特征的预测模型 ,工程实例分析表明了在不同条件下采用不同模型的合理性和实用性     

The Random Distribution of the Loading and Unloading Response Ratio Under the Assumptions of Poisson Models

This paper discussed the random distribution of the loading and unloading response ratio(LURR) of different definitions(Y_1～Y_5)using the assumptions that the earthquakes occurfollowing the Poisson process and their magnitudes obey the Gutenberg-Richter law.Theresults show that Y_1～Y_5 are quite stable or concentrated when the expected number of eventsin the calculation time window is relatively large(>40);but when this occurrence ratebecomes very small,Y_2～Y_5 become quite variable or unstable.That is to say,a high value ofthe LURR can be produced not only from seismicity before a large earthquake,but also from arandom sequence of earthquakes that obeys a Poisson process when the expected number ofevents in the window is too small.To check the influence of randomness in the catalogue tothe LURR,the random distribution of the LURR under Poisson models has been calculated bysimulation.90%,95% and 99% confidence ranges of Y_1 and Y_3 are given in this paper,which is helpful to quantify the random influe