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1.
地质力学模型实验作为一种便捷高效、成本低廉的研究方法,不仅可以将工程的破坏过程直观地呈现出来,而且可以作为了解工程整体力学特征、破坏模式和稳定情况的重要研究手段,在各类岩土工程问题的研究中有着广泛应用。由于地质力学模型材料的变形模量较低,同等应力条件下应变极其敏感,因此模型实验中变形测量显得至关重要。为了提升地质力学模型实验中变形量测的便捷性和准确性,对目前地质力学模型中对变形测量的主要方法进行总结分析。结果表明：目前对于模型变形量测的方法主要分为电测式测量方法、光学测量方法和机械式测量方法,其中电测式测量方法主要包括电阻式应变片法和位移计法,光学测量方法主要包括光纤类传感器法、数字图像相关法、光弹性贴片法和云纹干涉法,机械式测量方法主要包括百分表测量法和经纬仪观测法。通过对各种方法工作原理、主要应用案例及优缺点的阐述对比,得出不同方法的主要区别是测量范围和适用范围的差异,其中百分表测量法适用于测量小区域变形;测量内部变形可选择电阻式应变片法及光纤类传感器法;较大区域的变形可选择位移计法及光纤类传感器法;指定点位移可选择经纬仪观测法;全场观测可选择数字图像相关法、云纹干涉法以及光弹性贴片法。该成果可为相关地质力学模型实验的变形测量提供实验参考。 相似文献
2.
地质力学模型实验作为一种便捷高效、成本低廉的研究方法,不仅可以将工程的破坏过程直观地呈现出来,而且可以作为了解工程整体力学特征、破坏模式和稳定情况的重要研究手段,在各类岩土工程问题的研究中有着广泛应用。由于地质力学模型材料的变形模量较低,同等应力条件下应变极其敏感,因此模型实验中变形测量显得至关重要。为了提升地质力学模型实验中变形量测的便捷性和准确性,对目前地质力学模型中对变形测量的主要方法进行总结分析。结果表明：目前对于模型变形量测的方法主要分为电测式测量方法、光学测量方法和机械式测量方法,其中电测式测量方法主要包括电阻式应变片法和位移计法,光学测量方法主要包括光纤类传感器法、数字图像相关法、光弹性贴片法和云纹干涉法,机械式测量方法主要包括百分表测量法和经纬仪观测法。通过对各种方法工作原理、主要应用案例及优缺点的阐述对比,得出不同方法的主要区别是测量范围和适用范围的差异,其中百分表法适用于测量小区域变形;测量内部变形可选择电阻应变片法及光纤传感器法;较大区域的变形可选择位移计法及光纤传感器法;指定点位移可选择经纬仪观测法;全场观测可选择数字图像相关法、云纹干涉法以及光弹贴片法。该成果可为相关地质力学模型实验的变形测量提供实验参考。 相似文献
3.
Dorothee Dietrich 《Tectonophysics》1989,170(3-4):183-212
The Helvetic nappes of western Switzerland are discussed as an example of an arcuate foreland fold- and thrust belt in which active fold-axis parallel stretching occurred. Fold-axis parallel extension is recorded by:
1. (1) Incremental strain data from pressure shadow fibres. The significance of pressure shadow fibres for the determination of the deformation history of a region is discussed. Pressure shadows are used to quantify the amount of, and to describe the distribution of fold-axis parallel extension occurring in the Helvetic nappes.
2. (2) The extension directions of conjugate systems of en échelon veins. It is shown that an analysis of the geometry of conjugate vein systems can reveal a regional deformation pattern. The relative age of the conjugate en échelon vein systems in the Helvetic deformation history can be assessed, the geometry of the conjugate sets relative to the local anisotropy plane is described, and the significance of the preferred orientation of their extension directions is discussed.
3. (3) Fold-axis parallel sections. A comparison of the regional distribution of the fold-axis parallel strain with the shape of the Helvetic nappes in fold-axis parallel sections shows that the fold-axis parallel strain cannot be related to the footwall topography of the nappes.
It is concluded that the fold-axis parallel extension in the Helvetic nappes was induced by a change of direction of overthrust shear. This change occurred late in the deformation history and was superposed on the already formed nappes. The changing direction of overthrust shear is the expression of an overall anticlockwise rotation going on in the overthrusting Alpine nappe pile, relative to the European plate, a rotation which lead to the arcuate shape of the Western Alps. 相似文献
4.
5.
Terry Engelder 《Tectonophysics》1979,55(3-4)
Residual strain, a self-equilibrating recoverable strain that remains in rocks even after external forces and moments are removed, is found NNW of the folded Appalachian plateau in the Devonian Onondaga limestone and the Silurian Lockport dolomite and Grimsby sandstone of western New York. This residual strain is manifest upon overcoring by a NNW directed maximum expansion of the limestone and sandstone and a random maximum expansion of the dolomite. Strains, recorded with strain gauge rosettes bonded to outcrops, are as high as 200 με (microstrain). Double overcoring of the sandstone and dolomite relieves smaller strains of the same orientation as the initial overcore. X-ray analysis of the Grimsby sandstone shows that the elastic residual strain locked in quartz grains is characterized by a NE principal extension of 60 με and a 10–30 με NW principal compression oriented 30° counterclockwise from the NNW compression indicated by overcoring. Sonic velocity tests on samples in the lab indicate that Grimsby sandstone is anisotropic with a NNW maximum P-wave velocity of 4.05 km/sec. This anisotropy correlates with the residual strain in Grimsby sandstone. Mechanical twinning of calcite within both the Onondaga limestone and Grimsby sandstone indicates that the rock contains a permanent compressive strain of less than 2% in the NNW direction. The permanent strain becomes progressively smaller in a series of samples from Syracuse to Buffalo, New York. The development of solution cleavage in Onondaga limestone also indicates a NNW compression. No evidence of permanent strain was found in the dolomite. The NNW compression of the limestone and sandstone is normal to the fold axes of the Appalachian foreland fold and thrust belt. This geometric relationship indicates that the residual strain well beyond the outermost Appalachian folds was caused by the same tectonic stresses responsible for folding, the Appalachians during the late Paleozoic. Strain within the Appalachian plateau below the Silurian salt horizon suggests either the presence of a second décollement in, perhaps, Ordovician shales or a general NNW shortening of the crust under the Appalachian plateau. 相似文献
6.
骨节状石香肠构造应变计初探 总被引：2，自引：0，他引：2
考虑两期纯剪切变形成因的骨节状石香肠。假设骨节缝处香肠层的厚度近似等于香肠层的原始厚度,再根据等面积法原理恢复骨节状石香肠层的原始长度,求得石香肠层的拉伸有限应变,并采用物理模拟方法对骨节状石香肠等面积法进行了检验,误差范围分别为3.23%,2.84%,3.94%和6.82%。将该种方法应用于湖北铁山含骨节状石香肠岩石的有限应变测量,得到石香肠层的伸长有限应变值为33.80%~48.22%。再利用矩形断裂石香肠对骨节状石香肠应变测量结果进行检验,取得比较一致的结果。并将两期构造变形的岩石有限应变进行了分离。 相似文献
7.
苏通大桥主塔墩群桩基础是世界上规模最大的群桩基础,由131根长117 m的超长钻孔灌注桩组成。在这样的工程环境下工作的传感器不仅要承受巨大的压力作用,还受一些施工因素影响,极易损坏。为了提高传感器埋设的成活率,经过多次现场试验,提出了包括混凝土应变计、表面应变计、静力水准和水深传感器等多种传感器的保护技术。传感器保护技术的实施,使得传感器成活率得到保证,整个监测系统的平均成活率超过96%。并利用实测数据分析了超长桩的荷载传递和不均匀沉降规律,结果表明,超长钻孔灌注桩的荷载传递规律有别于一般的桩基础;大型群桩基础的不均匀沉降主要表现在横桥向,纵桥向的不均匀沉降可以忽略。 相似文献
8.
In south-west Ireland, hydrothermally formed arsenopyrite crystals in a Devonian mudstone have responded to Variscan deformation by brittle extension fracture and fragment separation. The interfragment gaps and terminal extension zones of each crystal are infilled with fibrous quartz. Stretches within the cleavage plane have been calculated by the various methods available, most of which can be modified to incorporate terminal extension zones. The Strain Reversal Method is the most accurate currently available but still gives a minimum estimate of the overall strain. The more direct Hossain method, which gives only slightly lower estimates with this data, is more practical for field use. A strain ellipse can be estimated from each crystal rosette composed of three laths (assuming the original interlimb angles were all 60°) and, because actual rather than relative stretches are estimated, this provides a lower bound to the area increase in the plane of cleavage. Based on the average of our calculated strain ellipses this area increase is at least 114% and implies an average shortening across the cleavage of at least 53%. However, several lines of evidence suggest that the cleavage deformation was more intense and more oblate than that calculated, and we argue that a 300% area increase in the cleavage plane and 75% shortening across the cleavage are more realistic estimates of the true strain. Furthermore, the along-strike elongation indicated is at least 80%, which may be regionally significant. Estimates of orogenic contraction derived from balanced section construction should therefore take into account the possibility of a substantial strike elongation, and tectonic models that can accommodate such elongations need to be developed. 相似文献
9.
《Journal of Structural Geology》1999,21(8-9):939-948
Strains in rocks can be observed but ancient stresses can only be inferred. We should re-examine the potential of strain geometry as the key to understanding and interpreting common shear structures ranging from faults to plastic shear zones. The concept of failure along zero extension directions can be applied to natural structures in rocks and is predicated on strain compatibility between differently strained volumes. Zero extension directions are considered for two strain configurations, plane strain (k=1) and uniaxial shortening (k=0). The crucial difference between shear fractures, or faults, and plastic yield zones is that the former are preceded by dilatation while the latter are isovolumetric. Volume changes during deformation affect the orientations of zero extension directions and hence of the resulting structures. With isovolumetric strain, yield occurs on planes at 45° to the principal shortening direction in plane strain and at 54.7° to this axis in uniaxial shortening. Uniaxial shortening experiments on rock samples allow estimation of the relative volumetric strains when yield zones initiate. When this volumetric strain is used to estimate the orientation of shear fractures in plane strain, ca 70° dips are predicted for normal faults at high crustal levels, decreasing downwards to 45°. 相似文献
10.
基于扩展裂纹尖端附近应变场分析,采用冲击载荷作用的三点弯曲梁进行试验,开展了应变片法确定Ⅰ型裂纹动态应力强度因子的研究。明确了应变片与裂纹扩展方向之间朝向角为特定锐角和钝角条件下,动态裂纹尖端附近的归一化应变采用与裂纹扩展速度、应变片黏贴位置相关的二项式来表示,给出了二项式的相关系数确定过程和动态应力强度因子计算式。结果表明,二项式的理论计算的应变与时间关系变化曲线与试验实测相吻合;选取曲线最大值两侧3/4峰值处的时间差为特征时间?t时,理论计算结果与实测的应变与时间关系一致性较高;选用理论计算和试验实测的应变与时间关系变化曲线最大值,结合计算式,确定Ⅰ型裂纹动态应力强度因子,同时,与采用动焦散线法计算的结果进行对比,验证了应变片法确定Ⅰ型裂纹动态应力强度因子的可行性。研究过程为应变片法在岩石断裂力学特征量的测定提供了理论基础。 相似文献
11.
热液矿床深部控岩控矿构造展布格局与深部矿床(体)空间定位格局等关键问题一直是制约深部勘查部署和实现找矿突破的焦点和难点。在阐述岩浆热液成矿系统矿田(床)控岩控矿构造深延格局主要研究方法的基础上,基于成矿构造体系控制多金属成矿系统、物化探异常信息系统映射多金属成矿系统的研究思路,以湘南地区黄沙坪—宝山铜锡多金属矿田(简称坪宝矿田)为例,构建了控岩控矿构造深延格局、指示控矿构造深延的综合指标评价体系研究的方法框架。据此,通过坪宝矿田控岩控矿构造解析与斑岩型热液成矿系统矿化蚀变分带等综合研究,提出了矿田内黄沙坪、宝山两个典型矿床控岩控矿构造深延格局及深部找矿有利构造部位,为该矿田(床)深部勘查部署和找矿预测提供了新思路和新方法。该方法无疑对深化其他热液成矿系统构造控岩控矿理论及有效开展深部找矿勘查均具有借鉴意义。 相似文献
12.
13.
注水问题的含水层位移模型求解的难点在于边界条件的恰当处理。根据Theis定流量抽水与注水水流模型的反对称特性,假定注水位移模型的无限远通量边界与抽水位移模型的无限远通量边界也具有反对称性,从而得到Theis定流量注水的含水层位移模型解答,发现定流量注水与抽水的含水层骨架颗粒位移速度、累计位移量、径向应变及切向应变的解答均互为反号值。注水过程中含水层在径向有两种形变区,依次为膨胀区和挤压区。在膨胀区和挤压区的界限处,径向位移取得最大值。如果假定含水层顶底板不动,注水导致的地层相对位移足以产生水井或油井套管变形和折断破坏。注水时含水层在切向处于恒拉张状态,这可能导致井壁围岩产生径向放射状张裂缝。 相似文献
14.
三维地应力计算模型研究 总被引：2，自引：0，他引：2
简要回顾了现有的三维地应力实测方法在实际工程应用中存在的局限性。对钻孔局部壁面应力全解除法进行了系统的研究,从理论上说明了由它确定三维地壳应力张量的可行性。采用线弹性有限元法对钻孔局部壁面应力解除过程做了数值模拟研究,分析了应力解除曲线的变化特征,给出了达到完全应力解除时解除深度和被解除岩芯直径之间的定量关系,还进一步分析了环形解除槽引起的应力集中对其附近局部孔壁应力分布的影响,从而为在钻孔孔壁的局部壁面上如何合理的布置应变计（花）提供了参考依据。最后对本课题的研究前景做了展望。 相似文献
15.
运动学涡度的理论与实践 总被引：5，自引：0，他引：5
一般剪切作用下,碎斑或顺剪切作用方向向前或逆向旋转向两特征方向或流脊(非旋转方向)靠拢。高应变条件下,二长比大于一特定值的碎斑,当其顺向或逆向旋转至以特征方向为渐近线的双曲线的稳定翼上时,便稳定下来不再旋转。二长比小于该值的碎斑将不断向前旋转。这一特定值位于该双曲线的顶点,相应的临界形态因子(B*)或/和两特征方向间夹角的余弦定义为运动学涡度(Wk)。Wk是确定一相关韧性变形带纯剪切和简单剪切组分相对大小的重要度量,是根据内旋转(涡度)与线应变速率之间的比值而定的数值度量。就变形带而言,一般剪切带的运动学涡度变化为0~1,纯剪切为零,简单剪切为1。这是一非线性尺度,纯剪切和简单剪切各占50%的运动学涡度为0.71,而不是0.5。运动学涡度可通过计算、图解(双曲线网(PHD)、刚性颗粒网(RGN)法、Passchier图解、Wallis图解)、极摩尔圆法和应力或瞬时增量应变方向获得。运动学涡度与有限应变测量相结合很可能是估算一地地壳减薄/伸展量或增厚/缩短量的最佳途径。变形过程中运动学涡度很可能变化,应根据不同时期形成的构造获得相应时期的运动学涡度。 相似文献
16.
Gregory H. Roder 《Tectonophysics》1977,43(3-4)
Two methods are presented whereby finite-strain data may be determined from naturally occurring irregular strain markers (polygons) which are of unknown pre-deformation shape and distribution, without assumptions as to the orientation of the finite-strain ellipse. The first method describes “construction” of ellipses within the polygons, these ellipses providing the basis for analysis by already developed techniques. The second method is a simple extension of Wellman's method, which graphically establishes a strain ellipse from angle and line data. 相似文献
17.
Most approaches in statistical spatial prediction assume that the spatial data are realizations of a Gaussian random field.
However, this assumption is hard to justify for most applications. When the distribution of data is skewed but otherwise has
similar properties to the normal distribution, a closed skew normal distribution can be used for modeling their skewness.
Closed skew normal distribution is an extension of the multivariate skew normal distribution and has the advantage of being
closed under marginalization and conditioning. In this paper, we generalize Bayesian prediction methods using closed skew
normal distributions. A simulation study is performed to check the validity of the model and performance of the Bayesian spatial
predictor. Finally, our prediction method is applied to Bayesian spatial prediction on the strain data near Semnan, Iran.
The mean-square error of cross-validation is improved by the closed skew Gaussian model on the strain data. 相似文献
18.
鱼嘴构造流变计研究与基于流变学的分类方案 总被引：2，自引：0，他引：2
如同膨缩型香肠构造一样,鱼嘴石香肠构造是存在岩石流变性差异的能干层与基质在纯剪切作用机制下形成的构造形迹。在深入研究鱼嘴构造形态与能干层基质流变性差异的基础上,运用物理模拟的方法,模拟出不同形态的鱼嘴香肠构造,反演出能干层基质粘度比与香肠形态之间的关系,进而得出一种关于鱼嘴香肠构造的经验流变计。
认识到鱼嘴构造的纯剪切作用机制及其平面应变的特点,通过对香肠现有的几何参数的测量和计算以及对香肠构造演化初始阶段几何参数的恢复,在合理假设的理想状况下,推导出鱼嘴构造的应变差折射流变计。
鱼嘴构造是流变行为下应变的结果,因此这种构造行迹不仅有几何学意义,更折射出流变学意义。在模拟实验与野外考察的基础上提出了一种基于流变学与剪切作用机制的鱼嘴构造分类方案。 相似文献
19.
《地学前缘(英文版)》2019,10(6):2101-2115
Veins and dikes are often oriented subparallel to the axial surfaces of folds in the adjacent layered or foliated rocks.This implies an awkward situation,since veins would lay in planes close-to-parallel to the maximum stretching axis.A series of geometric models have been conceived in order to gain insight into the possible mechanisms for their formation.The models are based on the analysis of a varied selection of field structures and on the review of similar structures in the existing literature.A first categorization consists on distinguishing between axial-planar veins achieved by either progressive or polyphase deformation.Five models of axial-planar veins resulting from progressive deformation are described and discussed:(1) fold-related veins associated with the standard folding mechanisms,(2) fracture arrays localized along the short limbs of folds(asymmetric fold-related veins),(3) folds associated with rotation of extension veins(vein-related folds),(4) high strain and transposition of early veins,and(5) high strain and late veins parallel to axial planar foliations(axial planar foliation-related veins).The axial planar geometry is achieved through variable amounts of progressive rotational strain,except in model 5,in which the co-planarity is acquired at the time of vein intrusion.The possibility for axial-planar veins to have developed in two distinct phases in the context of polyphase or polyorogenic tectonics has also been explored and discussed.This study contributes to a better understanding of the intriguing interplays between deformation,metamorphic and magmatic processes in orogenic belts. 相似文献
20.
基于黏弹性理论,对土的动弹性模量和阻尼比确定方法进行探讨,并结合青藏铁路沿线黏土在一系列温度下的动三轴试验结果,给出冻结黏土的动弹性模量和阻尼比的确定方法.结果表明：冻结黏土的骨干曲线不是双曲线,建议通过滞回曲线求冻土的动弹性模量和动应变幅,从而获得它们之间的关系;不同计算方法得到的阻尼比随动应变幅的变化趋势基本相同,用滞后角法计算得到的阻尼比整体小于用能量损失法计算得到的阻尼比,建议采用相关函数法计算应变滞后于应力的滞后角,然后用滞后角法计算土的阻尼比;冻结黏土的阻尼比随动应变幅的增加而增大. 相似文献