中卫活动断裂带地震破裂危险区演化特征模拟   总被引：2，自引：0，他引：2  

王爱国  杨斌  马巍  张向红 《高原地震》2004,16(1):9-17

通过建立的岩石破裂危险度KR及断层滑动危险系数KF2个判别指标,对中卫一同心活动断裂带进行粘弹性有限元数值模拟,得到该断裂带在现代构造应力场作用下大震后的应力演变及地震破裂危险区长度、范围、峰值、衰减规律等的演化特征。结果表明,该断裂带大震后应力场的调整主要产生于震后300～400年间,震后地震破裂危险区转移到断裂带的中西段,并逐渐向东迁移,范围越来越集中,最终转移到断裂带的弧形顶点部位(红谷梁附近)。  相似文献   

Rock Magnetism Study on Loess-Paleosol Sequence at Huixinggou Section of Sanmenxia Basin     

Li Xingwen  Zhang Peng  Qiang Xiaoke  Ao Hong 《地球科学进展》2017,32(5):513-523

Rock magnetism is the foundation of paleomagnetism and environmental magnetism study, and is effective in identifying the components, grain size and content of magnetic minerals in rocks and sediments. A systematic rock magnetism investigation has been conducted on the Huixinggou loess-paleosol sequence at Shuigou-Huixinggou Paleolithic site of Sanmenxia Basin in the southeastern Loess Plateau. Results show that the magnetic assemblage of the section is dominated by magnetite and maghemite, as well as hematite, exhibiting the average grain size of magnetic minerals is attributed to Pseudo-Single Domain (PSD). The variation curves of magnetic parameters are consistent and well comparable to marine oxygen isotope curves, with low values corresponding to the loess deposition during glacial periods, and high values corresponding to the paleosol development during interglacial periods, jointly demonstrating the glacial-interglacial cyclicities of magnetic mineral types, composition, and grain size of Chinese loess-paleosol sequences under the influence of alternating strengthening and weakening of Eastern Asian paleomonsoon over the Quaternary period. Comprehensive analysis reveals that the relative content of high-coercivity antiferromagnetic minerals is higher in loess than in paleosol, whilst the absolute content of high-coercivity antiferromagnetic minerals in paleosol is generally higher than that in loess accompanying increasing intensity of pedogenesis. The mass-specific magnetic susceptibility (χ) shows distinctly positive correlations with anhysteretic susceptibility (χ_ARM), Saturation Isothermal Remanent Magnetization (SIRM) and magnetic grain size dependent parameters (χ_ARM/SIRM and χ_ARM/χ), indicating that the pedogenic producing Single Domain (SD) and small PSD ferrimagnetic particles contribute significantly to the magnetic susceptibility enhancement.  相似文献   

川中高石梯-磨溪地区震旦系灯影组碳酸盐岩岩石类型及分布规律   总被引：2，自引：0，他引：2  

文龙  王文之  张健  罗冰 《岩石学报》2017,33(4):1285-1294

四川盆地川中地区震旦系气藏储量规模大,储层分布面积广。在Folk(1959)碳酸盐岩分类方案与张荫本等(1996)对粘结岩分类方案研究的基础之上,结合四川盆地震旦系灯影组的具体情况,提出新的划分方案。研究表明:(1)高石梯-磨溪地区震旦系灯影组碳酸盐岩岩石类型可分为3个亚类,10个微类。该方案不同之处在于把凝块(石)云岩归位颗粒岩,同时根据藻的形态把藻云岩进一步细分;(2)沉积岩类的发育和分布受沉积层序的控制。海侵体系域(TST)沉积阶段,以泥-粉晶云岩、微生物岩等正化学岩沉积为主。高位体系域(HST)沉积阶段,以凝块云岩、砂屑云岩等异化颗粒岩沉积为主。纵向上,岩性具有从暗色泥晶云岩→藻云岩→颗粒云岩→浅色泥晶云岩演化的特征,即泻湖亚相→藻丘亚相→颗粒滩亚相→台坪亚相的规律;(3)凝块云岩、砂屑云岩等颗粒岩是主要的储集岩类;(4)灯影组碳酸盐岩不同岩类的发育和分布对储层的发育起到控制作用。对灯影组的油气勘探,除了对岩溶作用的研究之外,还需要重视沉积古地貌、岩相展布特征的分析,有助于有效的预测灯影组储层"甜点区"。  相似文献   

Rock fall hazard control along a section of railway based on quantified risk     

Renato Macciotta  C. Derek Martin  David M. Cruden  Michael Hendry  Tom Edwards 《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2017,11(3):272-284

Rock falls represent a large percentage of landslide-related hazards reported by Canadian railways in mountainous terrain. A 54.7?km-long section of railway through the Canadian Cordillera is examined that experiences, on average, 18 rock falls each year. An approach for rock fall hazard management is developed based on quantified risk. The approach focuses on defining railway operation procedures (freight train operations and track maintenance) that comply with quantified risks. Weather-based criteria that define periods when rock falls are more likely to occur along the study area are examined. These criteria are used herein to reduce exposure to rock falls and reduce their consequences. Several freight train operation strategies are proposed that comply with a tolerable level of risk adopted in this study for illustrative purposes. The approach provides a simple, flexible and practical strategy for railway operations that can be regularly adopted by the operators, and that is based on a more comprehensive assessment of quantified risk.  相似文献   

“Transverse Action” – A model benchmark exercise for numerical analysis of the Callovo-Oxfordian claystone hydromechanical response to excavation operations     

《Computers and Geotechnics》2017

The Callovo-Oxfordian claystone (COx) is considered as a potential geological formation to host an industrial radioactive waste repository in France. A detailed understanding of the thermo-hydro-mechanical (THM) behavior of the COx is a key issue for design of different repository structures and the safety calculations of the project. More particularly, numerical modeling of induced fracture networks around drifts excavated at the main level of the Andra’s Meuse/Haut-Marne Underground Research Laboratory (M/HM URL) and short and long term behavior of the COx around these drifts are of great interest. Several constitutive models have been developed/used in the framework of the R&D and simulation programs of Andra. A model benchmark exercise has been launched since 2012 to provide an overall view of the developed models regarding the in situ observations. In this view, two series of test cases, respectively at material point scale and at drift excavation scale are defined. Different kinds of constitutive models based on the elasto-visco-plasticity concept, continuum damage mechanics, the rigid block spring method and two-scale computational homogenized model (CHM) are used within this exercise. The obtained results show that accounting for material anisotropy and strain localization treatment techniques can improve the obtained results when elasto-visco-plastic models are used. Damage mechanics based approaches and methods accounting for discontinuities through discrete elements provide also interesting insights especially when fracturing processes must be modeled. However, more efforts are necessary to improve the robustness of these kinds of approaches in the complex context of COx response to excavation works.  相似文献   

Hybrid finite-discrete element modelling of dynamic fracture and resultant fragment casting and muck-piling by rock blast     

《Computers and Geotechnics》2017

A state-of-the-art review is conducted to highlight the fracture mechanism in rock blast and advantages and limitations of various methods in modelling it. A hybrid finite-discrete element method (FEM-DEM) is implemented to simulate rock fracture and resultant fragment muck-piling in various blasting scenarios. The modelled crushed, cracked and long radial crack zones are compared with those in literatures to calibrate the hybrid FEM-DEM. Moreover, the hybrid modelling reproduces the rock fragmentation process during blasting. It is concluded that the hybrid FEM-DEM is superior to continuous and discontinuous methods in terms of modelling dynamic fracture of rock under blast-induced impact load.  相似文献   

Numerical 3D modeling of the effects of strain rate and confining pressure on the compressive behavior of Kuru granite     

《Computers and Geotechnics》2017

This paper deals with numerical modeling of the compressive behavior of granite rock under high strain rate dynamic loading and wide range of confining pressure. For this end, a constitutive model based on damage mechanics and viscoplasticity for rock is formulated and implemented in explicit dynamics FEM. The viscoplastic part is based on a simple power law type yield criterion that incorporates the rate-dependency with a linear viscosity term. Moreover, a Rankine type of tensile cut-off is employed. The damage part of the model is formulated with separate scalar damage variables in tension and compression. The model is calibrated for Kuru granite and validated with the experimental data from dynamic compression tests at the strain rate of 600 1/s up to 225 MPa of confining pressure. The numerical simulations demonstrate that, despite the underlying continuum modeling approach, the model captures the correct experimental failure modes, including the transition from single-to-multiple fragmentation, as well as the dynamic compressive strengths at different confining pressures.  相似文献   

Numerical investigation of the opening effect on the mechanical behaviours in rocks under uniaxial loading using hybrid continuum-discrete element method     

《Computers and Geotechnics》2017

Openings including their size, shape and distribution in rock play a significant role in the performance of rock related structures. The well-established knowledge in this area can contribute to the engineering practices, for example, underground space design, planning and optimisation in Civil and Mining Engineering and wellbore stability in Drilling Engineering, among others. Thus, understanding the failure mechanism of rock with openings is theoretically and practically meaningful. Laboratory testing on rock or rock-like materials with openings have been studied extensively in the literature, which, however, primarily focuses on the cracks/fractures. In this paper, a comprehensive numerical study on the effect of non-banded openings, i.e., circular, rectangular, and triangular opening, on the rock mechanical behaviour is performed using a hybrid continuum-discrete element method. It is revealed that the proposed simulation method can reproduce reasonably the crack initiation and propagation, and predict well the change of the mechanical behaviour due to the openings. In addition, the influence of the opening shape and opening ratio (=area of opening/specimen area) on the mechanical behaviour is also investigated.  相似文献   

SP-grain production during thermal demagnetization of some Chinese loess/palaeosol     

Ronghua Wang  Reidar Løvlie 《Geophysical Journal International》2008,172(2):504-512

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岩石临破裂前波速变化特征的实验研究   总被引：1，自引：0，他引：1       下载免费PDF全文

施行觉  赵闯  杨映希  温丹  李成波 《地球物理学报》2012,55(10):3386-3392

为了提高波速的测量精度以便能观测到岩石临破裂前波速的微小变化,采用了波形的数值化,波的叠加,波的互相关和DTE(Subsample delay time estimate)方法和cosine插值,使时间分辨率提高到0.001 μs,波速分辨率达到1 m/s.在较小的应力增量(0.17 MPa)下测量了波的延迟时间,进而得到速度随应力的变化规律.实验结果显示在0.98破裂强度时岩石波速最大,然后下降直到破裂,此期间的波速下降量约30m/s.同时对临破裂前波的主频能量进行了计算,其变化规律与波速相同,认为破裂前的有关变化与岩石膨胀有关.最后用涨落模型讨论了延迟时间的方差变化.  相似文献