预测和控制深基坑变形的抗隆起稳定系数法   总被引：1，自引：0，他引：1  

谢小林  贾坚 《上海国土资源》2004,107(1):22-27

本文讨论了在软土基坑工程设计施工中所涉及到的抗隆起稳定系数的合理计算方法；通过对大量上海深基坑工程的计算分析并结合现场实测数据论证了利用抗隆起稳定系数进行基坑变形预测和控制的合理性，并提出了适用稳定系数法控制基坑变形的设计计算预测公式：δh/H～Ks关系式。  相似文献   

Thermal decomposition of NH4-analcime     

A.Yu. Likhacheva  S. A. Veniaminov  E. A. Paukshtis 《Physics and Chemistry of Minerals》2004,31(5):306-312

The thermal decomposition of ammonium-exchanged natural analcime is characterized by gas chromatography, IR spectroscopy and X-ray diffraction. The de-ammoniation and dehydroxylation proceed in parallel throughout the decomposition, which evidences the instability of the protonated analcime framework. The mechanism of degassing of NH₄-analcime changes throughout its decomposition. At the initial step, the mechanism of de-ammoniation consists in thermal dissociation of NH₄⁺ molecule onto NH₃ and proton (framework OH group) and diffusion of NH₃ out of the structure. Subsequent decomposition and removal of the OH groups lead to a progressive loss of crystallinity. At this step, an apparent activation energy for NH₃ desorption is estimated to be 145(±13) kJ mol^–1. This value is within the upper limit of the activation energy characteristic for the NH₃ desorption from proton centres in large-pore zeolites. At the final step, the adsorption of NH₃ and protons onto the defect centres in the amorphosed aluminosilicate framework results in a significant increase of an apparent activation energy for the de-ammoniation and dehydroxylation up to 270(±20) kJ mol^–1.  相似文献   

基于Matlab的水准点稳定性分析   总被引：1，自引：0，他引：1  

姚占派  缑忠才 《现代测绘》2004,27(2):25-27

通过使用Matlab功能强大的数学软件，应用于测量工程的数据处理。具体解决变形监测中水准点是否稳定的判定问题。并通过计算实例说明其可行性和优越性。  相似文献   

中国海相油气田勘探实例(之一) 四川盆地罗家寨大型气田的发现和探明   总被引：21，自引：4，他引：21  

冉隆辉  陈更生  徐仁芬 《海相油气地质》2005,10(1):43-47

罗家寨气田发现于2000年,是四川盆地迄今为止发现的储量规模最大的一个气田,2002年探明储量为581.08×108m3。其下三叠统飞仙关组储层由碳酸盐岩蒸发台地边缘优质鲕粒滩白云岩构成,圈闭面积大,构造幅度高,具有一定的埋藏隐蔽性。论述了气田的发现和探明过程,气藏地质的特征,以及对碳酸盐岩气藏勘探的启示。  相似文献   

An analysis of storm-induced landslides in colluvial soils overlying mudrock sequences, southeastern Ohio, USA     

A. Shakoor  A.J. Smithmyer 《Engineering Geology》2005,78(3-4):257-274

In late-June, 1998, a series of thunderstorms dropped 16.5 cm (6.5 in.) of rain in a 72-h period over southeastern Ohio, causing extensive flooding, six deaths, and 179 million dollars in property damage. The storms also triggered more than 60 shallow landslides along a 64 km (40-mi) stretch of Interstate 77 between Buffalo and Marietta, Ohio. Almost all of the landslides were translational, occurring along the contact between colluvial soils and the underlying bedrock (shales, claystones, mudstones). Six sites were selected in the affected area for a detailed study of the shallow landslides. At each site, a record was made of the stratigraphy, slope geometry, number of landslides, landslide dimensions, hydrologic conditions, and influence of vegetation on landslide distribution. Both colluvial soils and underlying bedrock were sampled for laboratory investigations, which included determination of natural water content, grain size distribution, Atterberg limits, permeability, slake durability, and shear-strength parameters. Data from laboratory tests were used to perform sensitivity and stability analyses with respect to varying slope angles, strength parameters, and thicknesses of saturated colluvial soil. The results of the study indicate that the shallow landslides along Interstate 77 occurred when the colluvial soils reached 90% to 100% saturation, depending upon the slope angles.  相似文献   

Snow loads on wire mesh and cable net rockfall slope protection systems     

Shanzhi Shu  Thomas C. Badger 《Engineering Geology》2005,81(1):15-31

Snow load on mesh systems is complicated by many factors. This paper presents field instrumentation data on snow load variation with temperature, snowfall and snow depth on a mesh system. It was found that snow load pattern on mesh systems changed with temperature even without variation in snow depth. It reached its maximum value when the temperature rose just above freezing to melt the interface. The field data was used to formulate appropriate snow load models for the various conditions of temperature in the field. The snow load models were used to study the performance of a number of mesh systems in North America and estimate the interface friction that was prevalent for the different surface conditions.  相似文献   

昭通示范区黄金坝气田五峰—龙马溪组页岩气储层地质特征   总被引：5，自引：5，他引：0       下载免费PDF全文

伍坤宇  张廷山  杨洋  梁兴  周松源  张朝 《中国地质》2016,(1):275-287

昭通国家级页岩气示范区黄金坝气田是继礁石坝和长宁—威远之后中国又一个在页岩气勘探、开发领域实现重大突破的地区,为了系统地展示黄金坝气田页岩气资源富集的储层条件,为未来的勘探工作提供参考,以五峰—龙马溪组页岩气储层为研究对象,从区域地质条件、储层岩石学、物性和地球化学4个方面对该页岩气储层进行了综合研究。结果表明稳定的区域构造和良好的顶底板条件是黄金坝地区页岩气资源富集的关键,良好的保存条件使储层维持了较高的压力(压力系数1);较高的孔隙度(平均4%)和TOC含量(目的层2%)提供了良好的储集空间,使储层具有较高的含气量(1.35~3.48 cm3/g,平均2.50 cm3/g);天然气地球化学数据表明,区内天然气主要成分为CH4(97%),其次还含有少量的C2H6、C3H8和CO2;天然气同位素数据表明烃类C同位素组成发生了倒转,表明储层具有良好的封闭性。但储层孔隙系统较为复杂,且非均质性极强,从而导致渗透率较低,在储层改造施工过程中应予以充分考虑。总体上,黄金坝气田具有较好的开发前景,生产测试表明,区内直井压裂产量为0.5×104~3.5×104m3/d/井,水平井压裂产量可达12×104~40×104m3/d/井。  相似文献   

尕斯库勒盐湖中CO_2-卤水-盐岩相互作用模拟研究     

韩积斌  许建新  海擎宇  安朝  何天丽  马海州 《铀矿地质》2016,(1):54-59

利用PHREEQC软件模拟CO2侵入后,尕斯库勒盐湖中CO2-卤水-岩盐之间的相互作用。CO2侵入卤水层后,卤水中元素的化学形态种类和大小发生变化,特别是碳酸盐型的络合物形态增多。CO2侵入后,除了碳酸盐、石盐和硫酸盐矿物达到饱和被析出外,其余矿物的不饱和程度加剧,卤水的TDS增大,pH值减小。卤水中U的含量在CO2侵入后发生沉淀而减小。研究成果对深入评估区域内盐水层CO2地质封存的环境风险和利用CO2分离提取盐湖卤水中的铀元素提供理论依据。  相似文献   

Three dimensional seismic studies of deep-water hazard-related features on the northern slope of South China Sea     

《Marine and Petroleum Geology》2016

Mass transport deposits and geological features related to fluid flow such as gas chimneys, mud diapirs and volcanos, pockmarks and gas hydrates are pervasive on the canyon dominated northern slope of the Pearl River Mouth basin of the South China Sea. These deposits and structures are linked to serious geohazards and are considered risk factors for seabed installations. Based on high resolution three dimensional seismic surveys, seismic characteristics, distributions and origins of these features are analyzed. A distribution map is presented and geometrical parameters and spatial distribution patterns are summarized. Results show that various groups of the mapped features are closely tied to local or regional tectonism and sedimentary processes. Mass transport complexes are classified as slides near the shelf break, initially deformed slumps on the flanks of canyons and highly deformed slumps on the lower slope downslope of the mouth of canyons. We propose them to be preconditioned by pore pressure changes related to sea level fluctuations, steep topography, and fluid and fault activities. Gas chimneys are mainly located in the vicinity of gas reservoirs, while bottom-simulating reflectors are observed within the gas chimney regions, suggesting gas chimneys serve as conduits for thermogenic gas. Mud diapirs/volcanos and pockmarks are observed in small numbers and the formation of pockmarks is related to underlying gas chimneys and faults. This study aims at reducing risks for deep-water engineering on the northern slope of South China Sea.  相似文献   

Microstructural characteristics of the Whitby Mudstone Formation (UK)     

《Marine and Petroleum Geology》2016

When trying to improve gas productivity from unconventional sources a first aim is to understand gas storage and gas flow potential through the rock by investigating the microstructure, mineralogy and matrix porosity of unfractured shale. The porosity and mineralogy of the Mulgrave Shale member of the Whitby Mudstone Formation (UK) were characterized using a combination of microscopy, X-ray diffraction and gas adsorption methods on samples collected from outcrops. The Whitby Mudstone is an analogue for the Dutch Posidonia Shale which is a possible unconventional source for gas. The Mulgrave shale member of the Whitby Mudstone Formation can microstructurally be subdivided into a fossil rich (>15%) upper half and a sub-mm mineralogically laminated lower half. All clasts are embedded within a fine-grained matrix (all grains < 2 μm) implying that any possible flow of gas will depend on the porosity and the pore network present within this matrix. The visible SEM porosity (pore diameter > 100 nm) is in the order of 0.5–2.5% and shows a non-connected pore network in 2D. Gas adsorption (N2, Ar, He) porosity (pore diameters down to 2 nm) has been measured to be 0.3–7%. Overall more than 40% of the visible porosity is present within the matrix. Comparing the Whitby Mudstone Formation to other (producing) gas shales shows that the rock plots in the low porosity and high clay mineral content range, which could imply that Whitby Mudstone shales could be less favourable to mechanical fracturing than other gas shales. Estimated permeability indicates values in the micro-to nano-darcy range.  相似文献