地质岩心钻孔人工造斜方法实践          下载免费PDF全文

孙孝刚  卢忠友  张涛 《探矿工程》2016,43(11):15-20

在岩心钻探施工过程中,钻遇岩（矿）心脱落需要补取岩心,或钻具脱落、埋钻和烧钻需要绕障时,人工造斜方法是解决问题的有效手段。钻孔较浅,造斜孔段刚好在变径后的位置,且上部孔壁稳定,易于扩孔和下套管,宜选用异径偏心楔人工造斜;钻孔较深,不能改变口径,造斜孔段岩层硬度较大,宜选用同径偏心楔人工造斜;钻孔较深,造斜孔段岩层硬度不大（如煤系地层中的煤层、泥岩等）,宜选用同径自然造斜。选用偏斜楔造斜时,偏斜楔长度、偏斜角大小和导斜槽直径的合理选择,偏斜楔下入钻孔过程中的正确操作;选用同径自然造斜,水泥浆灌注孔段位置确定、水泥浆凝固后达到一定的强度和造斜过程中合理的钻进参数,是造斜成功的关键。  相似文献   

长江河口浮泥形成机理及变化过程   总被引：15，自引：0，他引：15  

李九发  何青  徐海根 《海洋与湖沼》2001,32(3):302-310

1976年以来，在长江河口盐水楔和最大浑浊带活动的河道进行了20余次现场观测，本文在现场观测资料基础上，确认长江河口浮泥由细颗粒泥沙组成，中值粒径在8－11.5um,小于2um的粘土占28.18%-36.39%,长江河口浮泥是悬沙在盐水混合环境中絮凝沉降于近义廾风暴潮再悬浮泥沙形成的高浓度浑水层，在成因类型上分为憩流浮泥，盐水楔浮泥和风暴潮浮泥，第1种在涨或落潮转流期低流时形成，规模大，厚度薄，第2种在盐水楔发育时形成，规模较小，厚度较大，第3种在大风后形成，规模大，厚度薄，第2种在盐水楔发育时形成，规模较小，厚度较大，第3种在大风后形成，规模大，范围广，若三者相遇，则浮泥厚度和范围最大，浮泥具有枯季，大小潮秽暴周期变化规律，长江河口河道多的浮泥层，浮泥层的变化与河口拦门沙的冲淤有良好的正相关。  相似文献   

Dynamic sliding of tetrahedral wedge: The role of interface friction     

D. Bakun‐Mazor  Y. H. Hatzor  S. D. Glaser 《国际地质力学数值与分析法杂志》2012,36(3):327-343

The role of interface friction is studied by slow direct shear tests and rapid shaking table experiments in the context of dynamic slope stability analysis in three dimensions. We propose an analytical solution for dynamic, single and double face sliding and use it to validate 3D‐DDA. Single face results are compared with Newmark's solution and double face results are compared with shaking table experiments performed on a concrete tetrahedral wedge model, the interface friction of which is determined by constant velocity and velocity stepping, direct shear tests. A very good agreement between Newmark's method on one hand and our 3D analytical solution and 3D‐DDA on the other is observed for single plane sliding with 3D‐DDA exhibiting high sensitivity to the choice of numerical penalty value. The results of constant and variable velocity direct shear tests reveal that the tested concrete interface exhibits velocity weakening. This is confirmed by shaking table experiments where friction degradation upon multiple cycles of shaking culminated in wedge run out. The measured shaking table results are fitted with our 3D analytical solution to obtain a remarkable linear logarithmic relationship between friction coefficient and sliding velocity that remains valid for five orders of magnitude of sliding velocity. We conclude that the velocity‐dependent friction across rock discontinuities should be integrated into dynamic rock slope analysis to obtain realistic results when strong ground motions are considered. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Depositional model for a prograding oolitic wedge,Upper Jurassic,Iberian basin     

《Marine and Petroleum Geology》2015

Facies architecture and bedding patterns of the Kimmeridgian Pozuel Formation (Iberian Basin) evidence that this 50–70-m thick oolitic-grainstone unit conforms to the Infralittoral Prograding Wedge (ILPW) model instead of the classic models used for interpreting oolitic grainstones sandbodies on carbonate ramps or platforms (i.e., bank-margin shoal complexes, beaches and beach ridges).Ten lithofacies have been distinguished in the Pozuel Formation: 5–10° dipping clinobedded oolitic grainstone foresets passing to tabular oolitic packstones-grainstones, which interfinger the muddy basinal bottomsets. Landwards, the clinobeds pass into subhorizontal topsets composed of trough cross-bedded to structureless oolitic grainstones; oolitic-skeletal grainstones with stromatoporoids and coral-stromatoporoid-microbial mounds. Siliciclastic lithofacies and oncolitic/peloidal packstones occur at the innermost position. These lithofacies stack in strike elongated, 5–20-m thick, 0,5–2 km dip-oriented wide, aggradational-progradational packages with complex sigmoid-oblique geometries.Lithofacies, depositional geometries and stacking pattern permit to summarize the main characteristic of such Upper Jurassic oolitic infralittoral prograding wedge potentially to be applied in other oolitic sandbodies both in outcrops and subsurface: 1) sediment production within the wave action zone, 2) grainstone-dominated textures, 3) prograding basinward onto basinal muds, 4) laterally (strike) extensive, paralleling the shoreline, 5) variable thickness, commonly of few tens of meters, 6) broadly sigmoidal to oblique internal architecture, with topsets, foresets and bottomsets, 7) dip of foresets close to the angle of repose, 8) topsets deposited in shallow-water, extending through the shoreface, from the shoreline down to the wave base, 9) mounds, either microbial or skeletal, may occur in the topsets.The coated-grains factory was along the high-energy, wave-dominated outer platform (topset beds), from where the mud was winnowed and the grains transported both landward to the platform interior, and seaward to the platform edge, from were the grains cascaded down the slopes as grain flows and mass flows, forming clinobeds. This genetic model can be applied to other grain-dominated lithosomes, some of them forming hydrocarbon reservoirs, e.g., the Jurassic Hanifa Formation and some Arab-D (e.g., Qatif Field) in Arabia, the Smackover Formation in northern Louisiana and south Arkansas, the Aptian Shuaiba Formation (e.g., Bu Hasa Field) and the Cenomanian Mishrif Formation (e.g., Umm Adalkh Field) of the Arabian Gulf.  相似文献   

Fission track and fault kinematics analyses for new insight into the Late Cenozoic tectonic regime changes in West-Central Sulawesi (Indonesia)   总被引：1，自引：0，他引：1  

Olivier Bellier  Michel Sbrier  Diane Seward  Thierry Beaudouin  Michel Villeneuve  Eka Putranto 《Tectonophysics》2006,413(3-4):201-220

A 3-D density model for the Cretan and Libyan Seas and Crete was developed by gravity modelling constrained by five 2-D seismic lines. Velocity values of these cross-sections were used to obtain the initial densities using the Nafe–Drake and Birch empirical functions for the sediments, the crust and the upper mantle. The crust outside the Cretan Arc is 18 to 24 km thick, including 10 to 14 km thick sediments. The crust below central Crete at its thickest section, has values between 32 and 34 km, consisting of continental crust of the Aegean microplate, which is thickened by the subducted oceanic plate below the Cretan Arc. The oceanic lithosphere is decoupled from the continental along a NW–SE striking front between eastern Crete and the Island of Kythera south of Peloponnese. It plunges steeply below the southern Aegean Sea and is probably associated with the present volcanic activity of the southern Aegean Sea in agreement with published seismological observations of intermediate seismicity. Low density and velocity upper mantle below the Cretan Sea with ρ  3.25 × 10³ kg/m³ and V_p velocity of compressional waves around 7.7 km/s, which are also in agreement with observed high heat flow density values, point out at the mobilization of the upper mantle material here. Outside the Hellenic Arc the upper mantle density and velocity are ρ ≥ 3.32 × 10³ kg/m³ and V_p = 8.0 km/s, respectively. The crust below the Cretan Sea is thin continental of 15 to 20 km thickness, including 3 to 4 km of sediments. Thick accumulations of sediments, located to the SSW and SSE of Crete, are separated by a block of continental crust extended for more than 100 km south of Central Crete. These deep sedimentary basins are located on the oceanic crust backstopped by the continental crust of the Aegean microplate. The stretched continental margin of Africa, north of Cyrenaica, and the abruptly terminated continental Aegean microplate south of Crete are separated by oceanic lithosphere of only 60 to 80 km width at their closest proximity. To the east and west, the areas are floored by oceanic lithosphere, which rapidly widens towards the Herodotus Abyssal plain and the deep Ionian Basin of the central Mediterranean Sea. Crustal shortening between the continental margins of the Aegean microplate and Cyrenaica of North Africa influence the deformation of the sediments of the Mediterranean Ridge that has been divided in an internal and external zone. The continental margin of Cyrenaica extends for more than 80 km to the north of the African coast in form of a huge ramp, while that of the Aegean microplate is abruptly truncated by very steep fractures towards the Mediterranean Ridge. Changes in the deformation style of the sediments express differences of the tectonic processes that control them. That is, subduction to the northeast and crustal subsidence to the south of Crete. Strike-slip movement between Crete and Libya is required by seismological observations.  相似文献   

贵州关岭大寨崩滑碎屑流灾害初步研究   总被引：3，自引：0，他引：3  

刘传正 《工程地质学报》2010,18(5):623-630

2010年6月28日,贵州省关岭县岗乌镇大寨村发生特大型崩滑碎屑(石)流灾害,造成99人死亡或失踪。通过现场考察崩滑区的地质环境与斜坡岩体结构,认为斜坡体由似"干砌块石结构"的裂隙化岩体组成是发生崩溃式破坏的主要内在原因。超常暴雨(过程雨量237mm)条件下斜坡岩体后缘裂缝充水形成持续的"水楔作用"是斜坡岩体松动、倾倒垮塌的主要外部引发因素。碎屑(石)流块度的空间分布具有从源头向沟口逐次减小,碎屑(石)流运动冲击高度逐步降低,冲击速度逐步减小,并显示4个能级4个冲程的特点。根据动势能守恒定律,计算了每个冲程的最大速度,得出第1冲程为高速崩滑,其它冲程属于碎屑(石)流动冲击。未发现区域天然地震、光照水库诱发地震与外围历史采矿活动与本次事件相关的直接证据。由于滑坡后缘仍存在不稳定岩体,碎屑(石)流堆积体上多处分布直径3～5m的堰塞塘,说明碎屑(石)空隙的排泄能力不足,在未来暴雨条件下引发新的崩滑或形成沟谷型泥石流的可能性是存在的。  相似文献   

大别山低级变质岩的构造背景     

徐树桐  吴维平  陆益群 《地质通报》2010,29(5):795-810

大别山南北两侧的浅变质岩是碰撞造山以前洋壳俯冲造山阶段的重要组成部分。木兰山片岩或张八岭群是俯冲的洋壳;苏家河群、信阳群和佛子岭群是由洋壳俯冲形成的海沟沉积,并因俯冲过程中的前进变形而形成增生楔;杨山煤系和梅山群是石炭纪弧前盆地沉积,并因俯冲过程中的前进变形而被增生楔逆掩。宿松群是扬子大陆被动边缘沉积,不是俯冲造山带的成员。因洋壳俯冲形成的弧和弧后盆地可能已被新生界沉积物掩盖。高压—超高压变质带是碰撞造山后期从深部折返的外来体。高压—超高压变质带正好处于洋壳和增生楔之间,破坏了早期洋壳俯冲造山带的完整性,使得洋壳俯冲造山阶段的特征被破坏,因而不易辨别。俯冲造山阶段应为奥陶纪到泥盆纪,碰撞造山阶段应从二叠纪开始。  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987110000034   总被引：5，自引：1，他引：4  

Dapeng Zhao  Lucy Liu 《地学前缘(英文版)》2010,1(1):31-44

<正>We synthesize significant recent results on the deep structure and origin of the active volcanoes in mainland China.Magmatism in the western Pacific arc and back-arc areas is caused by dehydration of the subducting slab and by corner flow in the mantle wedge,whereas the intraplate magmatism in China has different origins.The active volcanoes in Northeast China(such as the Changbai and Wuda-lianchi) are caused by hot upwelling in the big mantle wedge(BMW) above the stagnant slab in the mantle transition zone and deep slab dehydration as well.The Tengchong volcano in Southwest China is caused by a similar process in the BMW above the subducting Burma microplate(or Indian plate). The Hainan volcano in southernmost China is a hotspot fed by a lower-mantle plume which may be associated with the Pacific and Philippine Sea slabs' deep subduction in the east and the Indian slab's deep subduction in the west down to the lower mantle.The stagnant slab finally collapses down to the bottom of the mantle,which can trigger the upwelling of hot mantle materials from the lower mantle to the shallow mantle beneath the subducting slabs and may cause the slab—plume interactions.  相似文献   

Integration of natural data within a numerical model of ablative subduction: a possible interpretation for the Alpine dynamics of the Austroalpine crust     

M. RODA  M. I. SPALLA  A. M. MAROTTA 《Journal of Metamorphic Geology》2012,30(9):973-996

A numerical modelling approach is used to validate the physical and geological reliability of the ablative subduction mechanism during Alpine convergence in order to interpret the tectonic and metamorphic evolution of an inner portion of the Alpine belt: the Austroalpine Domain. The model predictions and the natural data for the Austroalpine of the Western Alps agree very well in terms of P–T peak conditions, relative chronology of peak and exhumation events, P–T–t paths, thermal gradients and the tectonic evolution of the continental rocks. These findings suggest that a pre‐collisional evolution of this domain, with the burial of the continental rocks (induced by ablative subduction of the overriding Adria plate) and their exhumation (driven by an upwelling flow generated in a hydrated mantle wedge) could be a valid mechanism that reproduces the actual tectono‐metamorphic configuration of this part of the Alps. There is less agreement between the model predictions and the natural data for the Austroalpine of the Central‐Eastern Alps. Based on the natural data available in the literature, a critical discussion of the other proposed mechanisms is presented, and additional geological factors that should be considered within the numerical model are suggested to improve the fitting to the numerical results; these factors include variations in the continental and/or oceanic thickness, variation of the subduction rate and/or slab dip, the initial thermal state of the passive margin, the occurrence of continental collision and an oblique convergence.  相似文献   

Debris flow and slide deposits at the top of the Internal Liguride ophiolitic sequence, Northern Apennines, Italy: A record of frontal tectonic erosion in a fossil accretionary wedge     

Michele Marroni  Luca Pandolfi 《Island Arc》2001,10(1):9-21

Abstract In the Northern Apennines, the Internal Liguride units are characterized by an ophiolite sequence that represents the stratigraphic base of a late Jurassic–early Paleocene sedimentary cover. The Bocco Shale represents the youngest deposit recognized in the sedimentary cover of the ophiolite and can be subdivided into two different groups of deep sea sediments. The first group is represented by slide, debris flow and high density turbidity current-derived deposits, whereas the second group consists of thin-bedded turbidites. Facies analysis and provenance studies indicate, for the former group, small and scarcely evoluted flows that rework an oceanic lithosphere and its sedimentary cover. We interpret the Bocco Shale as an ancient example of a deposit related to the frontal tectonic erosion of the accretionary wedge slope. The frontal tectonic erosion resulted in a large removal of materials, from the accretionary wedge front, that was reworked as debris flows and slide deposits sedimented on the lower plate above the trench deposits. The frontal tectonic erosion was probably connected with subduction of oceanic crust characterized by positive topographic relief. This interpretation can be also applied for the origin of analogous deposits of Western Alps and Corsica.  相似文献