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211.
城市地铁复杂洞群浅埋暗挖法的有限元模拟 总被引:17,自引:2,他引:17
以北京地铁复-八线王府井至东单区间隧道的施工为例,论述了城市复杂洞群浅埋暗挖法的有限元模拟,应用三维有限元理论研究、分析了施工效应问题,并对复杂洞群系统施工工艺进行了优化,解决了一系列施工中的难题,取得了很好效益。 相似文献
212.
基于GIS的黄河三角洲地下水开发适宜性评价模型 总被引:4,自引:0,他引:4
本文运用地理信息系统(GIS)技术,建立了黄河三角洲地区浅层地下水开发适宜性综合评价模型。评价模型考虑了浅层地下水补给,含水层导水性和储水性,地下水水质,土地利用以及地下水开采对环境影响等多方面因素,模型评价结果为地下水开发适宜性等级分区图。模型评价成果为黄河三角洲地区浅层地下水资源规划和开发利用提供了科学依据。 相似文献
213.
Since the late 1970s, the dynamic range and resolution of strong motion digital recorders have leaped from 65 to 135 dB, opening new possibilities for advanced data processing and interpretation. One of these new possibilities is the calculation of permanent displacement of the ground or of structures, associated with faulting or with non-linear response. Proposals on how permanent displacements could be recovered from recorded strong motion have been published since 1976. The analysis in this paper concludes that permanent displacements of the ground and of structures in the near-field can be calculated provided all six components of strong motion (three translations and three rotations) have been recorded, and the records are corrected for transducer rotation, misalignment and cross-axis sensitivity. 相似文献
214.
Anisotropy of the apparent resistivity variation rate near the epicentral region for strong earthquakes 总被引:1,自引:0,他引:1
IntroductionThe geo-electrical anisotropy before earthquake is of special significance for the prediction of earthquake location and for the research on crustal stress status near the epicentral region. The anisotropy has been studied from various aspects (CHEN, et al, 1983; QIAN, et al, 1985, 1996; LU, et al, 1990a; MAO, et al, 1995; RUAN, et al, 1999). But the anisotropic phenomena presented by geo-electrical data are not practically satisfactory and not clear as compared with the res… 相似文献
215.
Fragility curves express the probability of structural damage due to earthquakes as a function of ground motion indices, e.g., PGA, PGV. Based on the actual damage data of highway bridges from the 1995 Hyogoken‐Nanbu (Kobe) earthquake, a set of empirical fragility curves was constructed. However, the type of structure, structural performance (static and dynamic) and variation of input ground motion were not considered to construct the empirical fragility curves. In this study, an analytical approach was adopted to construct fragility curves for highway bridge piers of specific bridges. A typical bridge structure was considered and its piers were designed according to the seismic design codes in Japan. Using the strong motion records from Japan and the United States, non‐linear dynamic response analyses were performed, and the damage indices for the bridge piers were obtained. Using the damage indices and ground motion indices, fragility curves for the bridge piers were constructed assuming a lognormal distribution. The analytical fragility curves were compared with the empirical ones. The proposed approach may be used in constructing the fragility curves for highway bridge structures. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
216.
The Upper Permian Sedimentary Facies and Its Role in the Dajing Cu-Sn Deposit, Linxi County, Inner Mongolia, China 总被引:3,自引:1,他引:3
Gongjiong QIN Yosuke KAWACHI Liqing ZHAO Yongzheng WANG Qiang OU 《Resource Geology》2001,51(4):293-305
Abstract: Exhaustive investigations were launched for confirming the upper Permian host rocks of the Dajing Cu-Sn Deposit, probing into the possibility that Dajing is a Sedex type deposit during cosedimentation, complementing the deficiency of previous researches and going further into substantiating the role of the upper Permian strata in the control of ore distribution. After more than two years work, we reclassified the sedimentary facies in the Dajing area and its periphery as shallow fresh water lake and delta. Indicative sedimentary structures, such as ripple marks, rain marks, and mud cracks combined with contemporary fossils, were revealed. Having measured the flow directions, performed chemical comparison, and analyzed various sediments from sourceland in the Dajing area by XRF, we consequently redivided the strata into four sedimentary members, among which P2 l1 and P2 l2 were concluded as significant ore-hosted strata. The upper Permian basin was a lateral rift basin. The water and sediments in the basin are much deeper and thicker in the north than those in the south.
The indicators of special sedimentary facies, such as gravity flow, brine pool and synchronogenic stratiform structure of the ore cannot be found in the Dajing area. There was no growth fault, assemblage of sulfide and sulfate, and no zonation as well.
On the basis of study in this area, taking into account the paleosedimentary environment as capriciously flowing shallow lake, which approximated the state of oxidation, we figured that the paleogeography made it prohibitively difficult to form stratiform sulfide deposits which are prone to form in deoxidized environment. It can be ruled out the possibility that the Dajing deposit is a syngenetic deposit during sedimentation. 相似文献
The indicators of special sedimentary facies, such as gravity flow, brine pool and synchronogenic stratiform structure of the ore cannot be found in the Dajing area. There was no growth fault, assemblage of sulfide and sulfate, and no zonation as well.
On the basis of study in this area, taking into account the paleosedimentary environment as capriciously flowing shallow lake, which approximated the state of oxidation, we figured that the paleogeography made it prohibitively difficult to form stratiform sulfide deposits which are prone to form in deoxidized environment. It can be ruled out the possibility that the Dajing deposit is a syngenetic deposit during sedimentation. 相似文献
217.
赋存于茅口组下部含泥质灰岩段的矿体呈似层状、透镜状,长3500-5600m,平均厚4.39-5.15m,矿石品位一般8%-20%,最高可达65%。矿石有原岩型和粘土型两类,粘土型矿石一般呈灰-深灰色,干燥后呈灰白色,硬度1-2,比重1.6-2.3t/m^3,粘性强,可塑性好,透水性强。主要矿物成分有海泡石、石英、方解石、滑石、蒙脱石、伊利石和氟磷石等,矿石富Si、Mg、贫K、Na,CaO、Al2O3含量偏高。早二叠世江南古陆两侧局限(浅)海或海湾环境有利于海泡石沉积。在永顺-石门、安化-浏阳、怀化-浏阳成矿带,具有良好的找矿前景,估计海泡石资源量在3000万吨以上。 相似文献
218.
北京地区一次特大强风过程边界层结构的研究 总被引:21,自引:2,他引:21
利用北京325 m气象塔资料对1993年4月9日北京地区出现的一次特大强风过程的边界层结构(风、温、风切变及阵风特征)进行了分析。随着该次大风的过境,边界层内风场出现数个风速高值中心,高度位于200~300 m,时间间隔1~3 h。伴随上层风速垂直切变和阵风特性。湍流能谱的计算结果表明了大尺度涡旋对边界层湍流微结构的影响。 相似文献
219.
Therelationshipsbetwenearthquakesandpositionsofthesunandmoon(Ⅱ)——Sometemporalcharacteristicsoftheaftershocksequencesofstronge... 相似文献
220.