加载速率对岩石单轴压缩试验影响的数值模拟研究          下载免费PDF全文

黄靥欢  刘春  张晓宇  秦岩  邓尚 《高校地质学报》2019,25(3):423

在单轴压缩数值模拟试验中,加载速率由每次边界条件变化幅度和边界条件变化后的平衡计算时间这两个因素共同控 制。同样的加载速率,两个因素的不同组合也会对加载效果有很大的影响。因此,探究以上两因素对岩石单轴压缩数值模拟 试验的影响机制,可对高效进行高精度的各加载速率下的数值模拟试验起到积极作用。本文使用MatDEM软件,基于软件自 动设定的加载区间以及标准平衡迭代,设置不同的应力施加步数Nd与平衡迭代比率Rb,进行不同加载速率下的数值模拟试 验。模拟结果表明：（1）单步加载后平衡迭代次数越多（Rb越大）,该步中应力波传播与动能衰减越充分。在最优阻尼条件下, 当单步加载后平衡迭代次数等于40次（Rb等于0.8）时,每步加载中动能充分平衡,可以最低计算量取得准静态模拟结果; （2）单步加载应力增量越小（Nd越大）,数值模拟试验精度越高;（3）当加载速率一定即计算量相同时,为保证更高的模拟试验 精度,应采用低单步应力增量与低单步加载后平衡迭代次数（Nd大、Rb小）的加载方案。本文为定量研究岩石加载速率问题和 相关数值模拟提供了参考。  相似文献   

长春地区白垩系地层地铁勘察参数的确定     

郭红梅 《岩土工程技术》2019,(2):70-74

白垩系砾岩及泥岩地层在长春地区普遍存在,但由于砾岩地层现场钻探难以取样进行室内土工试验,泥岩地层由于存在水稳性、膨胀性、崩解性等因素影响,砾岩和泥岩的承载力值、抗剪强度参数指标、渗透系数以及基床系数等参数多以经验数据评估方法为主,在合理准确确定相关参数的问题上存在较大分歧。通过对长春地区白垩系砾岩及泥岩进行原位平板载荷试验、浸水载荷试验以及现场原位剪切试验,获取砾岩、泥岩的承载力值、抗剪强度指标、渗透系数以及现场基床系数值等,为地铁建设工程地质问题分析及设计提供充足的地质依据。  相似文献   

Quantitative prediction of discrete element models on complex loading paths     

Luc Sibille  Pascal Villard  Félix Darve  Rodaina Aboul Hosn 《国际地质力学数值与分析法杂志》2019,43(5):858-887

The ability of discrete element models to describe quantitatively (and not only qualitatively) the constitutive behaviour of a dense sand is assessed in this paper. Two kinds of 3D discrete models are considered. Both consider spheres as elementary particles. Nevertheless, the first model implements a contact law with rolling resistance whereas the second takes into account clumps made of two spheres. The discrete models are calibrated and validated from mechanical tests performed on a dense Hostun sand with a true triaxial apparatus. The calibration is carried out from axisymmetric drained compression tests, while the validation is discussed from monotonic and cyclic stress proportional loading paths and from a circular stress path in the deviatoric stress plane. The quality of the predictions of the discrete models are evaluated by comparison with the predictions given with advanced phenomenological constitutive relations, mainly an incrementally non-linear relation. Predictions given by the discrete models are remarkable, particularly when it is put in perspective with respect to the very few number of mechanical tests required for their calibration. However, these results and conclusions were reached in enabling conditions, and some limitations of such discrete models should be kept in mind.  相似文献   

Salt tectonics in a double salt‐source layer setting (Eastern Persian Gulf,Iran): Insights from interpretation of seismic profiles and sequential cross‐section restoration     

Jafar Hassanpour  Ali Yassaghi  Josep A. Muoz  Salman Jahani 《Basin Research》2021,33(1):159-185

Salt tectonics in the Eastern Persian Gulf (Iran) is linked to a unique salt‐bearing system involving two overlapping ‘autochthonous’ mobile source layers, the Ediacaran–Early Cambrian Hormuz Salt and the Late Oligocene–Early Miocene Fars Salt. Interpretations of reflection seismic profiles and sequential cross‐section restorations are presented to decipher the evolution of salt structures from the two source layers and their kinematic interaction on the style of salt flow. Seismic interpretations illustrate that the Hormuz and Fars salts started flowing in the Early Palaeozoic (likely Cambrian) and Early Miocene, respectively, shortly after their deposition. Differential sedimentary loading (downbuilding) and subsalt basement faults initiated and localized the flow of the Hormuz Salt and the related salt structures. The resultant diapirs grew by passive diapirism until Late Cretaceous, whereas the pillows became inactive during the Mesozoic after a progressive decline of growth in the Late Palaeozoic. The diapirs and pillows were then subjected to a Palaeocene–Eocene contractional deformation event, which squeezed the diapirs. The consequence was significant salt extrusion, leading to the development of allochthonous salt sheets and wings. Subsequent rise of the Hormuz Salt occurred in wider salt stocks and secondary salt walls by coeval passive diapirism and tectonic shortening since Late Oligocene. Evacuation and diapirism of the Fars Salt was driven mainly by differential sedimentary loading in annular and elongate minibasins overlying the salt and locally by downslope gliding around pre‐existing stocks of the Hormuz Salt. At earlier stages, the Fars Salt flowed not only towards the pre‐existing Hormuz stocks but also away from them to initiate ring‐like salt walls and anticlines around some of the stocks. Subsequently, once primary welds developed around these stocks, the Fars Salt flowed outwards to source the peripheral salt walls. Our results reveal that evolving pre‐existing salt structures from an older source layer have triggered the flow of a younger salt layer and controlled the resulting salt structures. This interaction complicates the flow direction of the younger salt layer, the geometry and spatial distribution of its structures, as well as minibasin depocentre migration through time. Even though dealing with a unique case of two ‘autochthonous’ mobile salt layers, this work may also provide constraints on our understanding of the kinematics of salt flow and diapirism in other salt basins having significant ‘allochthonous’ salt that is coevally affected by deformation of the deeper autochthonous salt layer and related structures.  相似文献   

沿海和岛屿重力海潮负荷改正模型——以马祖岛为例     

王继刚  周江存 《大地测量与地球动力学》2020,40(8):794-798

基于NAO99b全球海潮模型、NAO99Jb区域海潮模型、验潮站资料和SRTM地形数据确定的高空间分辨率海陆边界数据,构建我国沿海和岛屿高精度重力海潮负荷改正模型。以马祖岛为例介绍该模型,并采用实测的绝对重力测量资料进行验证。结果表明,经该模型改正后的重力观测精度明显提高。  相似文献   

海潮负荷效应对我国及周边IGS站的影响     

张红强  雷孟飞  王琪洁  彭葳  邵瑞 《测绘科学》2017,42(4)

针对近海区域海潮变化复杂且海潮负荷效应显著,而全球海潮模型在近海区域精度较低的问题,该文提出了将全球海潮模型NAO.99b和区域模型osu.chinasea.2010相结合,分析海潮对中国大陆及周边地区IGS站的影响。使用GAMIT软件解算IGS站实测数据,通过海潮负荷计算软件SPOTL对解算结果进行改正,并对改正效果进行对比和分析。结果表明,海潮负荷对中国及周边区域站点的影响主要体现在垂直方向,对一些站点的影响可以达到厘米级;海潮负荷对站点坐标的改正效果明显,特别是日本的种子岛站改正效果接近30%;站点改正效果从沿海到内陆逐渐减弱。  相似文献   

埋设地下光缆对武都地电影响的分析   总被引：3，自引：0，他引：3       下载免费PDF全文

高曙德  严正  康好林  苏永刚 《地震工程学报》1999,21(4):433-435

着重探讨武都地电台测区埋设地下光缆后北西道地电阻率测值急剧上升的原因.通过实际观测、理论分析和实验,总结出了这种变化的机制,定量地解释了埋设地下光缆对地电观测的影响,从而为以后判断地电测值变化是干扰还是地震异常提供了依据.  相似文献   

钢屈服—摩擦复合耗能器的性能研究   总被引：6，自引：1，他引：5  

周云  邓雪松 《地震工程与工程振动》1999,19(1):127-131

本文提出了“综合利用不同耗能原理和机制来设计新型耗能器”的思想,研究开发了钢屈服－摩擦复合耗能器,并对其进行了性能试验和对比试验,考察了耗能器的工作性能和耗能性能。给出了耗能器的恢复力模型,研究结果表明,钢屈服－摩擦复合耗能器利用钢屈服滞回和摩擦两种机制耗能,具有稳定的工作性能,耗能能力强且可调节,构造简单,形状紧凑,体积小,造价低,制作与安装方便,是一种有广阔应用前景的新型耗能减震装置。  相似文献   

嵌岩桩理论研究和设计中的几个问题   总被引：27，自引：0，他引：27  

刘树亚  刘祖德 《岩土力学》1999,20(4):86-92

明确嵌岩桩的定义和分类,对嵌岩桩的承载机理、临界嵌入深度、设计理论和数值模拟方法等问题进行讨论,并对未来的工作进行论述。  相似文献   

A Probabilistic Model for Fatigue Crack Propagation Analysis     

DING Keqin DUAN Menglan FU Pinsheng LIU Chuntu Ph. D.  Associate Professor  Research Department  Center of Boiler  Pressure Vessel Inspection  Research  Beijing  P. R. China Ph. D.  Research Professor  CCS Research  Development Center  China Classification Society  Beijing  P. R. China Lecturer  Yumen Petroleum School of Technique  Technology  Yumen  P. R. China Research Professor 《中国海洋工程》1999,(4)

A simple probabilistic model for predicting crack growth behavior under random loading is pre-sented.In the model,the parameters c and m in the Paris-Erdogan Equation are taken as random variables,and their stochastic characteristic values are obtained through fatigue crack propagation tests on an offshorestructural steel under constant amplitude loading.Furthermore,by using the Monte Carlo simulation tech-nique,the fatigue crack propagation life to reach a given crack length is predicted.The tests are conducted toverify the applicability of the theoretical prediction of the fatigue crack propagation.  相似文献