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133.
本文运用有限元法计算分析研究了多节扩孔钻孔灌注桩(DX桩)不同支盘数和支盘间距时土中应力场及其工作性状的变化规律,并从应力角度探讨了该桩对沉降的控制作用。 相似文献
134.
Emanuel Mazor 《Pure and Applied Geophysics》1978,117(1-2):262-275
Noble gases were studied in six wells, located on a 4.5 km south to north section across the Larderello field. Depth of wells, flow and gas/steam ratios are known to increase from south to north. Exploitation progressed in the same direction. The following noble gas patterns are observable: (a) Atmospheric Ar, Kr and Xe reflect productions of gas-depleted water at Colombaia 2 and progressively more gas-enriched steam towards the Gabbro wells. (b) Radiogenic4He and40Ar are observed in increasing concentrations from south to north. (c) The radiogenic and atmospheric gases reveal a positive correlation, indicating that the recharging water enters deep into the system, and gets well mixed with the radiogenic gases prior to the steam separation. (d) Gas contents and relative abundances of radiogenic argon decrease with production, thus supplying markers for the degree of exploitation in a well and a guide for optimum well spacing. (e) Excess neon over argon is observed and discussed in terms of crustal origin versus possible fractionation of atmospheric noble gases due to pertial steam separation. 相似文献
135.
Kazuo Konagai Yuanbiao Yin Yoshitaka Murono 《Soil Dynamics and Earthquake Engineering》2003,23(3):31-39
Most laterally loaded piles are flexible in the sense that they are not deformed over their entire lengths. Instead, pile deflections become negligible below an ‘active pile length’ La. This La is an important parameter that governs the overall behavior of a rigidly capped pile group. In the present approach, piles closely grouped together beneath a superstructure are viewed as a single equivalent upright beam whose stiffness matrix determines La. This idea is verified for different cases of pile spacing, and is further extended for nonlinear behavior of soils surrounding grouped piles. 相似文献
136.
上海地震台阵响应图及其计算方法 总被引:4,自引:0,他引:4
地震台阵的响应特性是衡量台阵对地震监测能力的重要标志。根据台阵响应特性,可分析台阵子台布局的合理性和波数分辨率。本文采用简单延时相加方法,并用不同频率下的波数k为上海地震台阵计算并绘制二维与三维的波数响应图。结果表明,该台阵响应图具有显著的主瓣峰,而且边瓣少且峰值低,具有较高的波数分辨率。 相似文献
137.
K. Thuro 《International Journal of Earth Sciences》1997,86(2):426-438
Usually the main subject in preliminary site investigations prior to tunnelling projects is the prediction of tunnel stability.
During the past years in conventional drill and blast tunnelling, problems have occurred also connected to the accurate prediction
of drillability in hard rock. The drillability is not only decisive for the wear of tools and equipment but is – along with
the drilling velocity – a standard factor for the progress of excavation works. The estimation of drillability in predicted
rock conditions might bear an extensive risk of costs. Therefore, an improved prediction of drilling velocity and bit wear
would be desireable. The drillability of a rock mass is determined by various geological and mechanical parameters. In this
report some major correlations of specific rock properties and especially geological factors with measured bit wear and drilling
velocity are shown.
Drilling velocity is dependent on a lot of geological parameters: Those principal parameters include jointing of rock mass,
orientation of schistosity (rock anisotropy), degree of interlocking of microstructures, porosity and quality of cementation
of clastic rock, degree of hydrothermal decomposition and weathering of a rock mass. Drilling bit wear increases with the
equivalent quartz content. The equivalent quartz content builds the main property for the content of wear-relevant minerals.
For various groups of rock types different connections with the equivalent quartz content could be detected. In sandstone
bit wear is also dependent on porosity or the quality of the cementation. Finally, an investigation program is submitted,
which helps to improve the estimation of rock drillability in planning future tunnel projects.
Received: 14 June 1996/Accepted: 10 January 1997 相似文献
138.
Rock mass characterization using photoanalysis 总被引:3,自引:0,他引:3
John A. Franklin Norbert H. Maerz Caralyn P. Bennett 《Geotechnical and Geological Engineering》1988,6(2):97-112
Summary Rock formations are distinguished from each other by measuring first the properties of the intact rock, and second those of the jointing. Whereas simple methods are available for measuring intact rock properties, those available for measuring jointing remain slow, expensive, and sometimes dangerous. Digitized photographs (photoanalysis) may provide a solution. In this paper, the new techniques of photoanalysis are reviewed together with applications, promising areas for research, and also some obstacles that remain to be overcome. Aspects of the rock mass that lend themselves to photoanalytical measurement include those of individual joints, such as persistence, orientation and roughness, and those relating to the mass as a whole, such as block size and the spacing or intensity of jointing. Photoanalysis can also be applied to measurement of blasting. It allows characterization of the rock about to be blasted, helping the engineer to predict fragmentation and to design an appropriate blasting pattern. Afterwards, the same methods can be used to measure fragmentation, overbreak and backbreak, for quality control and for diagnosis of problems.Presented at the 28th US ROck Mechanics Symposium, Tucson, Arizon, 29 June–1 July 1987. 相似文献
139.
为揭示线性剪切来流对串列双方柱绕流特性的影响,基于多步格式的特征线算子分裂有限元法,在计算域出口处采用对流边界条件,建立线性剪切来流的方柱绕流数值模型。对剪切参数为0~0.4的不同间距比下串列双方柱绕流数值模拟,结果表明:剪切来流可以抑制涡漩脱落,降低斯特劳哈数;上游方柱驻点随剪切参数的增加向高速侧移动,当剪切参数大于0.3时驻点的位置不再发生变化。进一步通过对比剪切参数分别为0和0.1的模拟结果发现:串列双方柱间隙内流场有无涡脱产生与该区域内水平方向时均速度场为负的区域是否连续有关;间距比和剪切参数通过改变方柱周围的速度场对作用于方柱表面的压力产生较大影响,迎流面与背流面的压力差剧增导致方柱平均阻力系数剧增。 相似文献
140.
为加强2022年北京冬奥会举办地区的震情保障工作,2019—2020年,依托原有地电台网,建设平谷、通州、阳原、大同、代县、临汾、宝昌、和林格尔等8个小极距井下地电阻率观测站(点),目前均运行良好,与同台地表大极距地电观测相比,观测数据精度提高。选取2021年9—11月井下地电阻率观测站数据记录,就相对均方差、日精度、月精度、月离散度、变化幅度等指标,分析小极距井下地电阻率观测数据质量。结果表明,8个井下地电阻率观测站(点)运行稳定,观测数据精度较高,具备一定映震效能,可为冬奥会举办区域及周边地区的震情跟踪有效服务。 相似文献