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节理岩体结构面产状的动态聚类分析 总被引：1，自引：0，他引：1
节理岩体结构面的优势产状是进行Mnote-carlo模拟和岩体稳定性分析的基础。玫瑰花图、等密度图等传统的图形分析方法比较粗糙,其结果只是相对的优势组数划分,无法准确地给出结构面的优势产状,使得分组结果在实际中应用不便。为弥补上述不足,采用改进的动态聚类分析方法,构造空间直角坐标系,以结构面的单位法向量表示其产状,并根据球面上两点之间的球面距离对结构面产状进行分类判定。将该方法应用于三峡库区巴东新县城铜盆溪桥东头高切坡结构面优势产状分析中。结果表明,采用改进动态聚类分析方法结果可靠,分类合理,可以较准确地确定结构面的优势产状。 相似文献
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《岩土力学》2017,(Z1):219-224
同一期地质运动中岩体所产生的结构面间距一般认为服从负指数分布。目前方法多根据产状单一因素进行分组,分组完成后同一组结构面的间距分布可能非常不规则,针对该问题,结合目前结构面采集到的数据质量高且具有空间位置等特点,提出一种新的双因素分组方法 (a new double-factor clustering method,NDCM)。分组时可综合考虑结构面产状与间距信息,该方法分组初值由模糊K均值法(fuzzy K-means)获取,通过调整隶属度较低的结构面分组编码达到修正结构面间距,使其满足负指数分布的目的。为获得NDCM的分组精度,进行了数值模型计算,该模型中结构面分组情况已知,利用模糊K均值法和NDCM法分别对此模型进行结构面分组。对比结果表明,NDCM法分组精度明显优于模糊K均值分组方法;重叠率越高组数越多这种优势越明显;相比于模糊K均值法,NDCM分组精度平均可以提升0.06左右。 相似文献
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结构面产状分析是进行岩体力学分析及稳定性评价的基础,玫瑰花图、等密度图等传统的图形分析方法较为粗糙,无法对产状数据进行准确分析,采用模糊聚类方法则可以得到较为准确的优势产状,但需要事先指定分组数及初始聚心,且模糊聚类算法为局部寻优算法,初始划分对最终的数据分析结果影响较大。为了得到较为客观的分组结果及优势产状,同时能够针对大量结构面产状数据进行聚类分析,提出了基于粒子群算法的岩体结构面产状模糊C均值聚类算法。采用粒子群算法进行模糊C均值聚类算法初始聚心的求解,在计算过程中可同时确定最佳分组数,避免了人为指定的主观性,克服了模糊C均值聚类算法易陷入局部极小值和对初始划分敏感的不足。最后,通过工程实例中不同方法的聚类效果对比分析该算法的有效性,并将该方法应用于实测结构面产状数据的分析,得到较为符合实际的优势结构面分组。 相似文献
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提出一种基于凝聚层次法和模糊C均值法的混合聚类法,用于对岩体结构面的优势组划分。该方法将结构面投放到在单位球面上,并使用欧式距离作为极点的相似性度量准则。先剔除结构面数据中的孤值产状,然后用凝聚层次法得到初步聚类结果,并将其作为FCM法的初始聚类中心,最后用FCM法划分优势组。通对人工生成产状样本的分组,验证了该法的正确性。将该方法应用于大藤峡坝址区实测的结构面数据的划分。在实测数据中寻找到两个孤值产状,成功将大藤峡D1y^1-3地层岩体结构面划分为两组,得到了符合实际的分组结果。 相似文献
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本文是在收集前人工作资料的基础上,通过野外地质查证,并进行了近70个节理点的调查(包括部分收集的)以及室内对节理进行分组,通过赤平极射投影的方法,先将沉积岩产状复平到原始水平状况,分析得出其相应的“萌芽剪理”。再根据共轭的“萌芽剪理”的产状,求出苏南各地质时期的三向主应力方位。岩石力学实验表明、岩石(体)受力后,最先形成的共轭剪裂,它们在空间方位上的分布与应力作用方向是具有明确规律。这对共轭剪 相似文献
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岩体结构面产状是影响岩体力学性质及工程稳定性的重要地质因素.从钻孔孔壁电视平展图上可较精确地提取结构面迹线上不共线三点的相对二维坐标(d, h),再利用空间解析几何理论确定其三维空间相对坐标(x, y, z),并求得结构面法向矢量.根据钻孔孔壁与坡面及结构面产状的空间几何关系,在保持原点不变的情况下,采用空间坐标变换的方法,将三维坐标系z轴和y轴分别转化为竖直方向z′和正北地理方向y′,并确定转化后坐标系空间的结构面法向矢量.再从结构面产状的定义出发,根据结构面法向矢量与结构面倾向、倾角的相关性,建立了一个空间几何模型,通过该模型可求得任意平直坡面上任一钻孔内局部岩体结构面的产状. 相似文献
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《中国煤炭地质》2015,(4)
通过对石楼北区块岩层与煤层中大量的节理产状分析,厘定了4套节理配套关系,并在此基础上恢复了4期构造应力场特征。研究认为:本区的节理走向以NWW—NNW、NNE—NE向为主,为燕山期NW—SE向和喜马拉雅期NE—SW向的构造应力作用下形成。多期构造应力的共同作用形成了煤层大密度割理,且煤层一组主要割理方向与现代应力场最大主应力方向较为一致,促进了煤割理的张开,提高了渗透率。煤层与围岩中节理产状的偏差,且节理裂隙中充填方解石,为煤层气的封闭与保存提供了有利的地质条件。煤层上覆岩层较软且节理密集时容易出现低应力差,造成煤层气富集,据此预测了研究区煤层气富集区。 相似文献
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段绪省 《陕西地质科技情报》1996,21(2):37-50
根据（１）脆性断裂的主构造面产状与擦痕，阶步要素或韧性断裂的主面理与ａ线理要素：（２）韧性断裂的Ｓｃ面理与Ｓｓ面理或主构面与片理面产状要素，定量推算其上盘运动的空间方向，并附Ｃａｓｉｏ ｆｘ－４０００Ｐ计算器用程序。 相似文献
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A Weichselian Late Pleniglacial fluvio-aeolian deposit has been investigated in the southern Netherlands. Three main structural lineaments have been distinguished: (1) very small, vertical platy structures (microjoints), in a parallel and a columnar configuration; (2) large joints and normal faults with minor displacement (‘Grubbenvorst type’), arranged in a conjugate fault-system; (3) large joints and normal faults (‘wedge-type’), located adjacent to ice-wedge casts. Since clay is absent, the occurrence of the vertical platy structures cannot be attributed to desiccation cracking. The vertical platy structures are interpreted as the result of thermal contraction cracking of a relatively thin layer, due to a sudden temperature drop. The large joints and normal faults of the Grubbenvorst type are the result of failure of the sediment due to the melting of the permafrost in the Late Pleniglacial, just before the formation of the Beuningen Gravel Bed. In other areas large periglacial convolutions have been formed during the same period. The normal faults and joints of the wedge type are more generally known. They are the result of failure of the sediment adjacent to a melting ice wedge. 相似文献
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PETER N. SOUTHGATE 《Sedimentology》1989,36(2):323-339
Stromatolite biostromes and bioherms in the lower two units of the Late Proterozoic Loves Creek Member of the Bitter Springs Formation represent shallowing upward and deepening upward sequences. In the central unit stromatolite form is governed by relative position in an asymmetric shallowing upward sequence. Ooid and/or peloid-intraclast grainstones and small, irregular bulbous and columnar stromatolites characterize the basal, transgressive portion of cycles. Domal, columnar and stratiform stromatolites comprise the bulk of the cycle. These forms accreted in a gradually shallowing epeiric sea. Domal stromatolites predominate in the deeper parts of cycles. Here synoptic relief gradually increases upwards. Columnar and stratiform stromatolites predominate in the shallower parts of cycles, where synoptic relief rapidly diminishes upwards. In thin-bedded dolo-mudstones at the tops of cycles the co-occurrence of desiccation cracks, tepee structures, scalloped dissolution surfaces, gypsum moulds and anhydrite nodule pseudomorphs provides evidence for subaerial exposure. In contrast, stromatolites in a unit at the base of the Loves Creek Member accreted during a gradual rise in sealevel. Stratiform, columnar and domal stromatolitic building blocks of the shallowing upward cycle are present in this deepening sequence, but only the lower half of the shallowing upward cycle is represented. Synoptic relief of the stromatolitic laminae gradually increases upward throughout the basal stromatolitic unit. Recognition of a deepening upward stromatolite sequence at the base of the Loves Creek Member, and a disconformity surface between this sequence and the underlying Gillen Member, permits palaeoenvironmental re-interpretation of the Loves Creek Member as a single ‘large scale’ sea-level cycle. 相似文献
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Individual Pennsylvanian clastic sediment intervals above the Seelyville Coal were examined on electric logs from Sullivan County, Indiana, U.S.A. for vertical sequence, interval thickness, and sand content. This information was used to evaluate local variability of this area of the Illinois Basin depositional system.Each clastic interval is composed of a lateral association of vertical sequences of sediments, bounded above and below by a thin association of coal, limestone, black shale, and/or underclay. An “average” constructive clastic unit is characterized by the following thickness parameters: mean
, standard deviation (s) = 3.4 m, minimum = 6.1 m, and
sand content, as measured by electric log resistivity, is 37%.Clastic sediment intervals characterized as “deep water” sediments tend to be clayrich, have the greatest lateral continuity, are composed of 50% to 90% coarsening upward sequences, are comprised of less than 16% fining upward sequences, and are composed of less than 10% of sequences of facies which are transitional between coarsening and fining upward. Sandstone channels are linear to coarsely dendritic and probably postdate lower portions of the coarsening upward sequences. One example of longshore shoaling between the Springfield and Houchin Creek coals was discovered. This is the youngest stratigraphic evidence of longshore currents in Illinois Basin clastic sediments. This milieu probably represents a distal delta position.Shallow-water sediments are sand-rich, complex, and gradational. They tend to be interfingered and to display poor lateral continuity. Coarsening upward sequences comprise less than 20% of the data sites. Fining upward fluvial sequences are represented by well-developed dendritic map patterns and constitute 20–30% of the sites. Transitional sequences between coarsening and fining upward log profiles are represented by both interfingered and gradational sequences and constitute 20–55% of the sites.Each constructive vertical sequence represents only a portion of the overall progradational deltatic environment.Destructive linear erosional channels are oriented downdip into the basin. The first occurrence in Indiana of the Trivoli Sandstone channel facies, located between the Ditney and West Franklin horizons, was delineated. Destructive channel sands are found commonly between the Houchin Creek and Colchester coals.Clastic subintervals locally began to develop when compacted unit thickness exceeded 18 m.Average regional wedging contributes 0.13 m/km to local sediment interval thickness variability. The average compacted clastic interval thickness has a local range of 19 m owing to local depositional environments. This variation is related closely to the overall clastic ratio of end-member sequences which are situated in close proximity. The average clastic unit varies in thickness of ± 1.4 m owing to the influence of compaction of the underlying Pennsylvanian sediment filling the Mississippian unconformity valleys. Compactional effects between clastic units become negligible as composite interval thickness exceeds 30 m. 相似文献
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Abstract. Simulation experiments with a one-dimensional static model for formation of methane hydrate are used to demonstrate models of hydrate occurrence and its generation mechanism for two end-member cases. The simulation results compare well with experimental data for two natural examples (the Nankai Trough and the Blake Ridge).
At the MITI Nankai Trough wells, the hydrate occurrence is characterized by strongly hydrated sediments developing just above the BGHS. Such occurrence can be reproduced well by simulation in which the end-member case of upward advective fluid flow from below the BGHS is set. The strongly hydrated sediments is formed by oversaturated solution with free gas which directly enters the BGHS by the upward advective fluid flow. The recycling of dissociated methane of preexisting hydrate also contributes to the increase of hydrate saturation.
At the Site 997 in the Blake Ridge area, the hydrate occurrence is characterized by thick zone with poorly hydrated sediments and no hydrate zone developing above the hydrate zone. Such occurrence can be reproduced well by simulation in which the end-member case of in-situ biogenic production of methane in the sediment of methane hydrate zone is set. The distribution pattern of hydrate saturation is basically controlled by that of TOC. However, the hydrate concentration near the bottom of the hydrate zone is increased by the effect of recycling of dissociated methane of pre-existing hydrate. No hydrate zone expresses the geologic time needed until the local concentration of methane exceeds the solubility by gradual accumulation of in-situ biogenic methane with burial. 相似文献
At the MITI Nankai Trough wells, the hydrate occurrence is characterized by strongly hydrated sediments developing just above the BGHS. Such occurrence can be reproduced well by simulation in which the end-member case of upward advective fluid flow from below the BGHS is set. The strongly hydrated sediments is formed by oversaturated solution with free gas which directly enters the BGHS by the upward advective fluid flow. The recycling of dissociated methane of preexisting hydrate also contributes to the increase of hydrate saturation.
At the Site 997 in the Blake Ridge area, the hydrate occurrence is characterized by thick zone with poorly hydrated sediments and no hydrate zone developing above the hydrate zone. Such occurrence can be reproduced well by simulation in which the end-member case of in-situ biogenic production of methane in the sediment of methane hydrate zone is set. The distribution pattern of hydrate saturation is basically controlled by that of TOC. However, the hydrate concentration near the bottom of the hydrate zone is increased by the effect of recycling of dissociated methane of pre-existing hydrate. No hydrate zone expresses the geologic time needed until the local concentration of methane exceeds the solubility by gradual accumulation of in-situ biogenic methane with burial. 相似文献
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枕、球—枕构造：地层中的古地震记录 总被引：15，自引：2，他引：13
枕状构造(pillow)与球—枕构造(ballandpillow)、负载构造(load))是地层中的软沉积物变形构造,它们在形态、产状、变形机制等方面是不同的。枕状构造是砂层中一组呈“凹”形弯曲的变形沉积体,它的原始层平行于枕状体的底面,顶面则是一个平直的截切面。枕状构造是由于层状砂层强烈液化向上覆软沉积砂层流动、穿刺,使之弯曲褶皱,在原地固定位置形成,因此枕状构造在一个层内是沿岩层走向呈现一系列相间隔的向形和很窄的背形。形成球—枕构造与负载构造的软沉积层包括细砂单元与上覆粗砂单元。他们的变形机制与砂层的液化作用有关。下伏细粒砂单元具强的液化变形而上覆粗砂单元为弱变形层。上覆粗砂单元（比重大）在下伏细砂单元（比重小）之上形成一个不稳定重力驱动系统,地震发生时的剪切力使重的粗砂（弱液化）陷落下沉至下伏细粒单元（强液化）中成负载构造和球—枕构造。球—枕体位于细砂层的不同位置,表明他们是下沉穿越细砂层单元为异地沉积体。形成枕、球—枕及负载体的软沉积物液化变形机制不同,但液化作用的触发机制是强地震。这些液化变形构造在实验室砂层的振动液化模拟实验中也已得到证实。地层中的枕状构造及球—枕、负载构造代表一次Ms>5的古地震灾变事件。古地震往往是沿着某些古地震断裂分布,是古地震断裂活动的表现。本文将举例讨论我国古老地层中的某些枕状构造、球—枕与负载构造,并简述当时发震的构造背景。 相似文献
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A smoothed particle hydrodynamics (SPH) framework for three-dimensional dynamic soil-multibody interaction modeling is presented, where both soils and rigid bodies are discretized using SPH particles. In the framework, soils are modeled using the Drucker-Prager model, while rigid bodies are considered with a multibody dynamics solver. A hybrid contact method suitable for three-dimensional simulations is developed to model the soil-body and body-body frictionless and frictional contacts, where contact forces are calculated based on ideal plastic collision and the unit normal/tangential vectors of the actual surface. Owing to its simplicity in contact detection and accuracy in contact force calculation, the hybrid contact method can be easily incorporated into SPH. Furthermore, graphics processing unit (GPU) parallelization is utilized to improve efficiency. The presented numerical framework and the hybrid contact method are validated using several examples. Numerical results are compared with analytical solutions and results from the literature. Furthermore, two three-dimensional simulations involving dynamic soil-multibody interaction are included to demonstrate the application. 相似文献
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北京西山地区雾迷山组风暴硅岩沉积序列 总被引：4，自引：1，他引：4
北京西山地区雾迷山组发育硅质条带白云岩，在硅质条带中发育典型的风暴硅岩沉积。风暴硅岩砾屑具菊花状构造和底模构造，与上下围岩形成典型的风暴序列。该序列从底部至顶部可划分为五个单元。每个单元分别代表正常天气至风暴天气再至正常天气的沉积特征。研究认为，风暴硅岩为在风暴流的影响下近源快速堆积的产物，并建立了风暴硅岩的沉积模式。 相似文献