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61.
为了解西太平洋雅浦海沟区俯冲带及岛弧两侧的海底热流分布情况,2015年1-3月期间的西太平洋海山航次中,"科学"号利用最新一代Lister型热流探针对该区域开展了海底热流原位测量工作。沿着横跨俯冲带的站位测线,本次进行了10个热流站位测量,共获得8个站位的有效数据。测量结果表明,该地区地温梯度的变化范围为0.011~0.137 Km-1,平均0.089 Km-1,热导率的变化范围为0.58~1.32 Wm-1K-1,热流值则在14.4~118.85 mWm-2之间,平均为68.02 mWm-2。热流值分布显示,雅浦岛弧附近具有较高的热流值,自雅浦岛弧向两侧热流值逐渐降低,低热流区主要分布在帕里西维拉海盆。由于该地区热流测量数据依然稀缺,深入的讨论有待进一步研究。  相似文献   
62.
南阳盆地是我国膨胀土主要分布地区之一,在宁(南京)西(西安)铁路施工工程地质调查中,发现南阳地区上第三系中新统湖相沉积膨胀土中发育的构造裂隙、中更新统冲洪积膨胀土中发育的卸荷裂隙和全新统湖沼相膨胀土中发育的收缩裂隙控制了路堑边坡病害的形式、规模和破坏特征。施工过程中采取了针对性措施治理边坡病害,取得了明显的工程效果。  相似文献   
63.
海滩层理由冲、回流塑造的向海倾前滨楔状交错层理和冲越流形成的向陆倾后滨斜层理组成,二者构成假背斜构造。近年在烟台—莱州岸段海滩上开挖了10个垂岸探槽,揭示出这里海滩以向陆倾后滨层理为主,并且被暴风浪侵蚀面所斜切,该面向海的前滨层理只留下几十厘米的薄层,说明近几十年海岸持续遭受侵蚀,海滩的前滨层理被多次暴风浪切割掉;按暴风浪期后滨层理层系特征分析,海岸蚀退率为1~1.5 m/a,与其他方法得到的结论相仿。个别探槽亦见前滨层理为主,反映出局部淤岸环境。由此说明,海滩层理的组构特征可以标志海岸的淤、蚀动态。  相似文献   
64.
为探索大学生地方认同的组成结构,以武汉大学为例,通过非结构访谈手段获取第一手研究资料,运用扎根理论分析大学生地方认同维度,并在此基础上设计调查问卷,利用探索性因子分析方法进一步分析大学生地方认同维度结构特征。研究发现:武汉大学大学生地方认同具有认知、情感、行为、自我效能和承诺5个维度的结构特征;学生对学校的地方认同较高;入学时间、所属学部、高考志愿、籍贯是地方认同形成的主要影响因素。大学生的个人背景(年级、所属学部、高考志愿、籍贯)不同,在地方认同及其各个维度上有较大差异。  相似文献   
65.
A series of model tests were performed to investigate the behavior of vertical pressure imposed on the bottom of a trench. The tests were conducted in two phases to generate soil arching due to soil deformation: (1) the backfilling phase and (2) the lowering-bottom phase. First, the backfilling phase was performed by filling sand into the trench, in which soil deformation was developed due to selfcompaction by the weight of the sand. The lowering-bottom phase was then conducted by lowering the bottom plate of the trench to induce additional soil deformation. The behavior of the vertical pressure acting on the bottom of the trench during the backfilling phase can simulate that of the vertical pressure imposed on the bottom of buried rigid pipes. The behaviors of buried flexible pipes could be observed during the lowering-bottom phase, in which both the minimum and the maximum vertical pressures could be obtained according to the induced soil deformation. A novel method for predicting the vertical pressures in each phase was proposed. The agreements between the predictions by the proposed method and the experimental results were demonstrated.  相似文献   
66.
Journey-to-work mode choice is intertwined with ideological and pragmatic issues. This article reexamines such issues using socioeconomic data from the decennial census and American Community Survey (ACS). It investigates the structure of variables with exploratory data analysis (EDA) because this technique advises the formation of hypotheses and the specification of cause and effect. Traditional EDA reveals the nonnormal structure of raw data, mapping illustrates associations between transit and income, and both methods suggest the presence of a transit-by-choice population among affluent metropolitan residents. The results yield three hypotheses concerning propensity to use transit that have previously received little attention.  相似文献   
67.
本文利用三维广义反演技术对重力资料进行反演,计算出了琉球沟弧盆系地区的莫氏面深度。由于考虑了分辨率和方差之间的最佳折衷问题,反演结果不论是在精度上还是在分辨能力方面都有了明显改进。分析结果也表明,重力反演得到的莫氏面深度同李昭兴等人用地震折射波法得到的莫氏面深度有较大的差别。文中地产生这种差别的可能原因提出了自己的见解。  相似文献   
68.
CTD (Conductivity-Temperature-Depth) data at five stations across the Izu-Ogasawara Trench at 34°N were examined. Geostrophic velocity was in accordance with the directly measured currents. Above the trench floor, potential temperature increased at a rate of 0.6 m°C/1000 db from 8000 db to 9417 db, and salinity increased from 8300 db to the bottom. Potential density was almost constant at 7100–8700 db, and it increased to the bottom. Above the eastern and western flanks, inversion of potential density was indicated in the bottom layers with an increase of potential temperature and a decrease of salinity, suggesting geothermal heating and outflow of ground water.  相似文献   
69.
70.
Deep CTD Casts in the Challenger Deep,Mariana Trench   总被引:1,自引:0,他引:1  
On 1 December 1992, CTD (conductivity-temperature-depth profiler) casts were made at three stations in a north-south section of the Challenger Deep to examine temperature and salinity profiles. The station in the Challenger Deep was located at 11°22.78′ N and 142°34.95′ E, and the CTD cast was made down to 11197 db or 10877 m, 7 m above the bottom by reeling out titanium cable of 10980 m length. The southern station was located at 11° 14.19′ N and 142°34.79′ E, 16.1 km from the central station, where water depth is 9012 m. CTD was lowered to 7014 db or 6872 m. The northern station was located at 11°31.47′ N and 142° 35.30′ E, 15.9 km from the central station, and CTD was lowered to 8536 db or 8336 m, 10 m above the bottom. Below the thermocline, potential temperature decreased monotonously down to 7300–7500 db beyond a sill depth between 5500 m and 6000 m, or between 5597 db and 6112 db, of the trench. Potential temperature increased from 7500 db to the bottom at a constant rate of 0.9 m°C/1000 db. Salinity increased down to 6020–6320 db, and then stayed almost constant down to around 9000 db. From 9500 db to the bottom, salinity increased up to 34.703 psu at 11197 db. Potential density referred to 8000 db increased monotonously down to about 6200 db, and it was almost constant from 6500 db to 9500 db. Potential density increased from 9500 db in accordance with the salinity increase. Geostrophic flows were calculated from the CTD data at three stations. Below an adopted reference level of 3000 db, the flow was westward in the north of Challenger Deep and eastward in the south, which suggests a cyclonic circulation over the Challenger Deep. Sound speed in Challenger Deep was estimated from the CTD data, and a relation among readout depth of the sonic depth recorder, true depth, and pressure was examined.  相似文献   
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