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1.
采空区岩层移动的动态过程与可视化研究 总被引：3，自引：0，他引：3
矿山开采引起上覆岩层的移动是一个复杂的动态过程。在岩层的移动和变形过程中岩体具有流变性质，同时岩层的层状组合结构在运动过程中存在时间和空间上的差异。根据流变力学理论和薄板弯曲理论研究了岩层和地表移动的时间、空间过程，推导出考虑时间因数的地表下沉基本公式和获得岩层与地表下沉时间系数的公式。并基于MATLAB软件强大的数学计算和图形功能，开发了相应的模拟地表沉陷动态过程的可视化程序，对某开采煤矿的地表沉陷动态过程进行预测。其预测结果与该矿长期的实际观测资料基本一致，从而为地表沉陷的动态过程预测提供了新的方法。 相似文献
2.
R. K. N. D. Rajapakse 《国际地质力学数值与分析法杂志》1988,12(4):419-436
The axisymmetric problem of flexure of a centrally loaded or uniformly loaded thin-elastic plate resting on or buried in a transversely isotropic elastic half-space is solved using a constraint variational scheme. A fundamental solution corresponding to a unit vertical pressure acting over an annular region in the interior of the half-space which is derived through the application of Hankel integral transforms is used to evaluate the strain energy of the elastic half-space. The deflected shape of the plate is represented by a power series of radial coordinate together with a term corresponding to a concentrated load derived from classical plate theory. The coefficients of the power series representation, which could be considered as generalized coordinates corresponding to the interaction problem, are determined through the minimization of a constraint energy functional. The energy functional consists of the strain energies of the plate and half-space, the potential of the applied loads and a term corresponding to plate edge boundary conditions incorporated with a penalty number. The entire formulation is developed as a convenient and flexible matrix solution scheme. The numerical stability and convergence of the solution scheme are established, and the response of the plate is investigated over a range of relative rigidities of practical interest. 相似文献
3.
The effective lithospheric elastic thickness of the continent is an important parameter for examination of the large-scale structure and analyses of the mechanism of isostatic compensation within the plate, and a parameter standing for the strength of the lithosphere.The Te values along Quanzhou-Heishui,the southeast section of the Arctic Ocean-Eurasian Continent-Pacific Ocean geoscience transect, are estimated by using the coherence technique developed by Forsyth.Studies of the feature of the coher-ence between gravity and topography suggest that at short wavelengths(6.6-100km)for each data box that is used to estimate Te,the plate is strong enough to support topographic loads and gravity and topog-raphy are uncorrelated.At long wavelengths where the plate is deflected by surface and subsurface loads are compensated by the flexure model.Sichuan land-stone with low heat-flow values has high Te values whereas in Ninghua,Datian,land-stone with high heat-flow values has low Te values,which reflects a correlation,low heat-flow values corresponding to high Te values and high heat-flow values corresponding to low Te values.Te values can be divided into two sections:northwest high section and southeast low sec-tion.There is roughly a positive correlation between crustal thickness and effective elastic thickness of the lithosphere. 相似文献
4.
北冰洋-欧亚大陆-太平洋地学断面东南段岩石圈有效弹性厚度 总被引：4，自引：1，他引：4
大陆岩石圈有效弹性厚度（Te）是表示岩石圈强度的参数，计算该参数对研究岩石圈大规模构造，分析大陆板块内的均衡补偿机制有一定意义。利用Forsyth提出的相关技术计算的北冰洋－欧亚大陆－太平洋地学断面东南段自黑水到泉州的Te值，并分析了重力和地形波长的相关性特征，初步认为：计算Te值所选的每个数据块在短波长（6.6-100km)内岩石圈板块的强度足以平衡地形负载，重力和地形不相关；在长波长（100－250km)内，地形及地下负载由弯曲模型补偿，岩石圈板块在地形及地下负载作用下而挠曲。断面通过地段具有较低热流密度值的陆核有较高的Te值，具有较高热流密度值的宁化，大田地区有较低的Te值，反映了较高的热流密度值对应较低的Te值，较低的热流密度值对应较高Te 值的关系，Te可分为南东低值段和北西高值段，地壳厚度大体上与Te值呈正相关关系。 相似文献
5.
Preseismic lithospheric deformation at a subduction zone can be modelled as dip-slip dislocation on an inclined fault or as
flexure of a thin plate. Both these models predict a region of positive topography known as forebulge or outer rise. By matching
the location and the magnitude of the forebulge, we derive useful relations between the dip-slip fault parameters and the
plate parameters. In particular, we determine the width of a long dip-slip fault of given dip corresponding to a semi-infinite
plate of given thickness. The displacement profiles of the two models are also compared. 相似文献
6.
To assess the possibility that the North Atlantic Ocean may subduct at Scotian basin east of Canada, we investigate the present compensation state of this deep basin. A Fourier domain analysis of the bathymetry, depth to basement and observed gravity anomalies over the oceanic area east of Nova Scotia indicates that the basin is not isostatically compensated. Moreover, the analysis emphasizes that in addition to the sediments, density perturbations exist beneath the basin. The load produced by the sediments and these density perturbations must have been supported by the lithosphere. We simulate the flexure of the lithosphere under this load by that of a thin elastic plate overlying an inviscid interior. It is shown that a plate with a uniform rigidity does not adequately represent the lithosphere beneath the basin as well as the oceanic lithosphere far from the basin, rather the rigidity of the lithosphere directly beneath the basin is about one to two orders of magnitude smaller than elsewhere. We relate this weakening to the thermal blanketing effects of the thick sediments and the fact that the lithosphere has a temperature-dependent rheology. We suggest that this weak zone would have a controlling effect on the reactivation of normal faults at the hinge zone of the basin, that were formed during the break-up of Africa and North America and were locked in the early stages after the break-up. The weak zone would facilitate reactivation of the faults if tensional stresses were produced by possible reorientation of the spreading direction of the North Atlantic Ocean in the future. The reactivation of the faults would create a free boundary condition at the hinge zone, allowing further bending of the lithosphere beneath the basin and juxtaposition of this lithosphere to the mantle beneath the continent. This may provide a favorable situation for initiation of slow subduction due to subsequent compressional forces. 相似文献
7.
From a synthesis of data on volcanic evolution,movement of the lithosphere,and mantle velocities in the Baikal-Mongolian region,we propose a comprehensive model for deep dynamics of Asia that assumes an important role of the Gobi,Baikal,and North Transbaikal transition-layer melting anomalies.This layer was distorted by lower-mantle fluxes at the beginning of the latest geodynamic stage(i.e.in the early late Cretaceous) due to avalanches of slab material that were stagnated beneath the closed fragments of the Solonker,Ural-Mongolian paleoceans and Mongol-Okhotsk Gulf of Paleo-Pacific.At the latest geodynamic stage,Asia was involved in east-southeast movement,and the Pacific plate moved in the opposite direction with subduction under Asia.The weakened upper mantle region of the Gobi melting anomaly provided a counterflow connected with rollback in the Japan Sea area.These dynamics resulted in the formation of the Honshu-Korea flexure of the Pacific slab.A similar weakened upper mantle region of the North Transbaikal melting anomaly was associated with the formation of the Hokkaido-Amur flexure of the Pacific slab,formed due to progressive pull-down of the slab material into the transition layer in the direction of the Pacific plate and Asia convergence.The early—middle Miocene structural reorganization of the mantle processes in Asia resulted in the development of upper mantle low-velocity domains associated with the development of rifts and orogens.We propose that extension at the Baikal Rift was caused by deviator flowing mantle material,initiated under the moving lithosphere in the Baikal melting anomaly.Contraction at the Hangay orogen was created by facilitation of the tectonic stress transfer from the Indo-Asian interaction zone due to the low-viscosity mantle in the Gobi melting anomaly. 相似文献
8.
9.
中西太平洋海山区的岩石圈有效弹性厚度及其地质意义 总被引：2，自引：0，他引：2
中西太平洋海山区是太平洋板块上洋壳年龄最老、磁条带异常最复杂、海山分布最密集、地质构造最独特、构造活动最强烈的一个区域, 为探讨区内众多海山的构造成因, 以板块构造理论为指导运用弹性板挠曲理论计算了中西太平洋海山区岩石圈的有效弹性厚度.结果显示, 研究区的有效弹性厚度总体上表现为北西高南东低的趋势, 西边的麦哲伦海山链表现出南北低中间高的趋势, 东边的中太平洋海山群呈现出由西往东厚度递减的现象, 且这2个典型区域的岩石圈有效弹性厚度与现今法属玻利尼西亚群岛处的比较接近.据此推测它们是在白垩纪期间(约130~90 Ma)形成于现今法属玻利尼西亚群岛处的大规模热点群附近, 且受到了后期火山岩浆活动的改造作用. 相似文献
10.
本区构造发展存在三个不同阶段，印支期为初始褶皱阶段；燕山期为逆冲推覆定型阶段；喜马拉雅期为改造与破坏阶段。其地质结构明显具有双重构造，构造反转和推覆滑税三大特征。区内地震反射特征与岩性组合有一定对应关系，本文首次尝试利用地震反射信息特征对沉积环境进行分析。 相似文献
11.
土拱效应广泛存在于结构?土相互作用体系中,并不可避免地受到动荷载的影响。为探究循环荷载下土拱的演化过程,开展了循环加载下的活动门试验,结合粒子图像测速法（PIV）,对土拱的结构形态、位移场及竖向应力的变化规律进行了分析。结果表明,初始土拱形成时活动门上方产生三角形脱空区,施加循环荷载后该结构边界逐渐沿竖向延伸并向填土表面发展,位移场影响范围呈扇形向两侧扩大。根据初始差异沉降的不同,土拱的发展演化呈现出最终状态的差异：达到新的稳定状态,或发生失稳破坏。循环荷载下,初始活动门位移较大时土拱更易趋于破坏,表现为脱空区贯通填土表面并形成竖向滑裂面。土拱结构的稳定性受到脱空区土体堆积对其下边界的支撑作用影响。 相似文献
12.
Monte Kietpawpan Parichart Visuthismajarn Charlchai Tanavud Mark G. Robson 《Natural Hazards》2008,46(1):89-106
A new model to calculate tsunami travel times in the Andaman Sea region has been developed. The model specifically provides
more accurate travel time estimates for tsunamis propagating to Patong Beach on the west coast of Phuket, Thailand. More generally,
the model provides better understanding of the influence of the accuracy and resolution of bathymetry data on the accuracy
of travel time calculations. The dynamic model is based on solitary wave theory, and a lookup function is used to perform
bilinear interpolation of bathymetry along the ray trajectory. The model was calibrated and verified using data from an echosounder
record, tsunami photographs, satellite altimetry records, and eyewitness accounts of the tsunami on 26 December 2004. Time
differences for 12 representative targets in the Andaman Sea and the Indian Ocean regions were calculated. The model demonstrated
satisfactory time differences (<2 min/h), despite the use of low resolution bathymetry (ETOPO2v2). To improve accuracy, the
dynamics of wave elevation and a velocity correction term must be considered, particularly for calculations in the nearshore
region. 相似文献
13.
《Journal of Structural Geology》2001,23(2-3):165-182
An almost horizontal pahoehoe surface in a Holocene plagioclase basanite lava on Tenerife displays three scales of fracture within the surface crust. An early-formed set of large-scale fractures divides up the surface into an orthogonal set of rectangular slabs with dimensions of several metres and depths of 10–12 cm. The shortest slab dimension is parallel to the flow emplacement direction, inferred from a strong surface lineation. The slabs are domed with the centre an average of 9.6 cm (with range 4–19.6 cm) above the edges of the slabs. Profiles of the slabs normal and perpendicular to the margins and through the crest indicate that they can be described by a power law in which the deflection of the slab, h, is related to the distance from the crest, x, with an exponent between 2 and 3. Analysis of joints within the slabs indicates two smaller scale networks. An intermediate scale joint network bounds blocks with rectilinear to polygonal shapes in plan-view and has a characteristic mean spacing of 24.2 cm (range 10.5–48 cm). The major fractures in this set are normal and parallel to the slab margins. A smaller-scale joint network bounds polygonal equant blocks in plan-view and has characteristic spacing of 6.4 cm (range 3.7–10.5 cm). A model of cooling from the pahoehoe surface is used to constrain the growth of the crust and timing of fracture development. The large-scale slabs are attributed to localised accumulation of gas beneath the growing crust causing buoyant forces. The tensile stresses caused by uplift are sufficient to form the large-scale fractures after 2 or 3 h of cooling. The intermediate scale fracture network is attributed to the flexure of the slab crust. The smaller scale polygonal joint network is related to the build up of isotropic tensile stresses in the cooling slab crust due to thermal contraction with fracture development being promoted by the flexure of the slabs. An analysis of the slab deformation indicates that lava crust is weak. The weakness is explained by division of the crust into three zones: an outer zone with small scale joints that cause negligible strength, a middle zone of elastic behaviour in which stress can build up, and a lower zone of plastic deformation. The crustal slabs display profiles similar to that expected in a bending elastic plate. The deformation of the 10-cm-thick crust can be explained if the elastic zone was about 2-cm thick. This result agrees with an independent calculation of elastic zone thickness based on the position of the brittle–ductile transition being located at the 600°C isotherm at a depth of about 2 cm when the crustal slabs were rifted apart. 相似文献
14.
黏弹性地基板在矩形变速荷载作用下的振动分析 总被引：1，自引：0，他引：1
利用双重Fourier变换方法,首先推导得到了黏弹性地基板在多个矩形变速移动荷载作用下的动力响应一般解。然后以实际刚性路面为算例,采用快速傅立叶变换(FFT)方法对匀变速荷载作用下的板的动挠度进行了数值求解。与经典解进行了比较,显示出了较好的一致性。利用数值结果重点分析了矩形移动荷载的加速度、减速度以及初速度对板的动态挠度的影响,发现移动荷载加速度、减速度及初速度对黏弹性地基板动力响应的影响十分明显,随着加速度（减速度）和初速度的增大,板的动挠度在关键速度时明显减小;板的动挠度出现峰值的位置对应着不同的加速度（减速度）和初速度,但却对应着相同的关键速度。 相似文献
15.
Filippo Bandini Alejandro Lopez-Tamayo Gonzalo Merediz-Alonso Daniel Olesen Jakob Jakobsen Sheng Wang Monica Garcia Peter Bauer-Gottwein 《Hydrogeology Journal》2018,26(7):2213-2228
Observations of water surface elevation (WSE) and bathymetry of the lagoons and cenotes of the Yucatán Peninsula (YP) in southeast Mexico are of hydrogeological interest. Observations of WSE (orthometric water height above mean sea level, amsl) are required to inform hydrological models, to estimate hydraulic gradients and groundwater flow directions. Measurements of bathymetry and water depth (elevation of the water surface above the bed of the water body) improve current knowledge on how lagoons and cenotes connect through the complicated submerged cave systems and the diffuse flow in the rock matrix. A novel approach is described that uses unmanned aerial vehicles (UAVs) to monitor WSE and bathymetry of the inland water bodies on the YP. UAV-borne WSE observations were retrieved using a radar and a global navigation satellite system on-board a multi-copter platform. Water depth was measured using a tethered floating sonar controlled by the UAV. This sonar provides depth measurements also in deep and turbid water. Bathymetry (wet-bed elevation amsl) can be computed by subtracting water depth from WSE. Accuracy of the WSE measurements is better than 5–7 cm and accuracy of the water depth measurements is estimated to be ~3.8% of the actual water depth. The technology provided accurate measurements of WSE and bathymetry in both wetlands (lagoons) and cenotes. UAV-borne technology is shown to be a more flexible and lower cost alternative to manned aircrafts. UAVs allow monitoring of remote areas located in the jungle of the YP, which are difficult to access by human operators. 相似文献
16.
Analyses of bathymetry, gravity and seismic reflection data of the diffusive plate boundary in the central Indian Ocean reveal
a new kind of deformed structure besides the well-reported structures of long-wavelength anticlinal basement rises and high-angle
reverse faults. The structure (basement trough) has a length of about 150 km and deepens by up to 1 km from its regional trend
(northward dipping). The basement trough includes a rise at its center with a height of about 1.5km. The rise is about 10
km wide with rounded upper surface and bounded by vertical faults. A broad freeair gravity low of about 20 mGal and a local
high of 8 mGal in its center are associated with the identified basement trough and rise structure respectively. Seismic results
reveal that the horizontal crustal compression prevailing in the diffusive plate boundary might have formed the basement trough
possibly in early Pliocene time. Differential loading stresses have been generated from unequal crust/sediment thickness on
lower crustal and upper mantle rocks. A thin semi-ductile serpentinite layer existing near the base of the crust that is interpreted
to have been formed at mid-ocean ridge and become part of the lithosphere, may have responded to the downward loading stresses
generated by the sediments and crustal rocks to inject the serpentinites into the overlying strata to form a classic diapiric
structure. 相似文献
17.
The axisymmetric elastic response of circular footings and anchor plates in a linearly non-homogeneous elastic soil is analysed. It is assumed that footings/anchors are flexible and subjected to axisymmetric vertical loads. The response of the footing/anchor is modelled by using the classical Poisson–Kirchhoff thin plate theory. A variational technique is used to analyse the interaction problem. A representation for the contact stress is established by using a fundamental solution corresponding to a unit vertical pressure acting over an annular region in the interior of the non-homogeneous soil. The fundamental solution can be derived by using rigorous analytical procedures. The influence of the footing flexibility and the degree of soil non-homogeneity on the displacements, bending moments and contact stresses of a surface footing is examined over a wide range of governing parameters. In the case of anchor plates the influence of depth of embedment, degree of soil non-homogeneity and anchor flexibility on the anchor displacement is investigated. 相似文献
18.
简要回顾了岩石圈均衡理论的发展及岩石圈区域均衡和挠曲理论在岩石圈动力学研究中起的作用,阐述岩石圈有效弹性厚度(Te)的概念和特征。强调Te的研究是地质学和地球物理学的紧密结合,即通过岩石圈挠曲理论和区域均衡原理,对地形和重力资料进行谱分析计算,来获取岩石圈的物理性质信息。计算的Te(和相应的挠曲刚度)是岩石圈等效的强度,与爆破地震、地震层析成像和大地电磁测深等方法观测到的岩石圈和地壳厚度不同,它们之间只有通过岩石圈的屈服刚度包络面(YSE)才能比较。大洋和大陆岩石圈YSE的理论计算,表明Te值显著小于地震学的地壳和岩石圈厚度。尤其对于大陆岩石圈,地壳厚度、热年龄和应变率均可显著影响岩石圈的强度。本文还以滇西为实例介绍了对相干值曲线计算的新认识和当前岩石圈Te研究的最新趋势。 相似文献
19.
M. Ravi Kumar D. C. Mishra B. Singh D. Ch. Venkat Raju M. Singh 《Journal of the Geological Society of India》2013,81(1):61-78
Spectral analysis of digital data of the Bouguer anomaly map of NW India suggests maximum depth of causative sources as 134 km that represents the regional field and coincides with the upwarped lithosphere — asthenosphere boundary as inferred from seismic tomography. This upwarping of the Indian plate in this section is related to the lithospheric flexure due to its down thrusting along the Himalayan front. The other causative layers are located at depths of 33, 17, and 6 km indicating depth to the sources along the Moho, lower crust and the basement under Ganga foredeep, the former two also appear to be upwarped as crustal bulge with respect to their depths in adjoining sections. The gravity and the geoid anomaly maps of the NW India provide two specific trends, NW-SE and NE-SW oriented highs due to the lithospheric flexure along the NW Himalayan fold belt in the north and the Western fold belt (Kirthar -Sulaiman ranges, Pakistan) and the Aravalli Delhi Fold Belt (ADFB) in the west, respectively. The lithospheric flexures also manifest them self as crustal bulge and shallow basement ridges such as Delhi — Lahore — Sagodha ridge and Jaisalmer — Ganganagar ridge. There are other NE-SW oriented gravity and geoid highs that may be related to thermal events such as plumes that affected this region. The ADFB and its margin faults extend through Ganga basin and intersect the NW Himalayan front in the Nahan salient and the Dehradun reentrant that are more seismogenic. Similarly, the extension of NE-SW oriented gravity highs associated with Jaisalmer — Ganganagar flexure and ridge towards the Himalayan front meets the gravity highs of the Kangra reentrant that is also seismogenic and experienced a 7.8 magnitude earthquake in 1905. Even parts of the lithospheric flexure and related basement ridge of Delhi — Lahore — Sargodha show more seismic activity in its western part and around Delhi as compared to other parts. The geoid highs over the Jaisalmer — Ganganagar ridge passes through Kachchh rift and connects it to plate boundaries towards the SW (Murray ridge) and NW (Kirthar range) that makes the Kachchh as a part of a diffused plate boundary, which, is one of the most seismogenic regions with large scale mafic intrusive that is supported from 3-D seismic tomography. The modeling of regional gravity field along a profile, Ganganagar — Chandigarh extended beyond the Main Central Thrust (MCT) constrained from the various seismic studies across different parts of the Himalaya suggests crustal thickening from 35-36 km under plains up to ～56 km under the MCT for a density of 3.1 g/cm3 and 3.25 g/cm3 of the lower most crust and the upper mantle, respectively. An upwarping of ～3 km in the Moho, crust and basement south of the Himalayan frontal thrusts is noticed due to the lithospheric flexure. High density for the lower most crust indicates partial eclogitization that releases copious fluid that may cause reduction of density in the upper mantle due to sepentinization (3.25 g/cm3). It has also been reported from some other sections of Himalaya. Modeling of the residual gravity and magnetic fields along the same profile suggest gravity highs and lows of NW India to be caused by basement ridges and depressions, respectively. Basement also shows high susceptibility indicating their association with mafic rocks. High density and high magnetization rocks in the basement north of Chandigarh may represent part of the ADFB extending to the Himalayan front primarily in the Nahan salient. The Nahan salient shows a basement uplift of ～ 2 km that appears to have diverted courses of major rivers on either sides of it. The shallow crustal model has also delineated major Himalayan thrusts that merge subsurface into the Main Himalayan Thrust (MHT), which, is a decollment plane. 相似文献
20.
中国中西部前陆盆地的地质特征及油气聚集 总被引：35，自引：2，他引：35
中国中西部前陆盆地具有十分丰富的油气资源,近年来油气勘探也取得了很大的成果,但总体上来说其地质情况复杂、研究程度较低。世界上典型的前陆盆地一般位于造山带和稳定的克拉通之间的狭长槽地,而在中国中西部则主要为与古特提斯造山带在新特提斯阶段再活动有关的陆内会聚形成的“再生”前陆盆地,因此与世界典型前陆盆地相比中国中西部前陆盆地具有一定的“特殊性”。根据两期前陆的叠合程度差异造成的盆地几何形态、挠曲沉降、地层层序、沉积充填、构造变形特征的特点,将中国中西部前陆盆地归纳为改造型、新生型、叠加型和早衰型四种组合类型的前陆盆地。中西部不同组合类型前陆盆地具有不同的结构特征,决定了不同组合类型前陆盆地成藏特征和油气勘探潜力上的差异。 相似文献