三向应力作用下节理岩体渗流-应力耦合特性     

孔洋  朱珍德  阮怀宁 《岩土力学》2018,39(6):2008-2016

节理岩体渗流-应力耦合特性研究是岩石力学领域的重点和难点。水利水电工程与地下工程中天然节理岩体往往处于三向不等压应力状态,针对三向应力状态下节理岩体渗流-应力耦合特性研究较少。其中,单节理岩体渗流-应力耦合特性研究是基础。首先分析与探究了单节理岩体侧向应力作用效果及渗流作用机制,在单节理岩体渗透性-应力耦合分析模型基础上推导了单节理岩体渗流-应力耦合的理论公式。通过室内真三轴渗流-应力耦合试验,基于全局优化算法的非线性拟合及块体离散元数值仿真,验证了所提出理论公式的合理性。基于电路原理,给出了模拟电路与渗流问题的相似物理量,通过引入等效渗流阻方法,探究了典型的含正六边形主干节理网络的渗流-应力耦合特性。该研究结果对实际工程岩体的渗流分析有一定的参考价值。  相似文献   

大兴安岭中段突泉地区早白垩世碱性流纹岩锆石U-Pb定年及岩石成因     

宋维民  杜继宇  那福超  庞雪娇  杨佳林  刘英才  孙巍  陶楠  葛锦涛 《地质通报》2019,38(4):619-631

LA-ICP-MS锆石U-Pb年龄表明,突泉地区碱性流纹岩锆石的~(206)Pb/~(238)U年龄分别为135±1Ma、133±1Ma,属于早白垩世岩浆活动的产物。岩石地球化学资料表明,碱性流纹岩具富SiO_2、K_2O和高TFeO/MgO值,低Al_2O_3、CaO和MgO的特征,属于高钾钙碱性系列岩石,稀土元素总量较高,轻、重稀土元素分馏明显,具右倾的稀土元素分布模式,负Eu异常明显,相对富集Rb、U、Zr、Hf,亏损Sr、Ti、Nb、Ta等元素,花岗岩判别图解上,样品分布在A型花岗岩区;在Nb-Y-3Ga图解上,显示拉张构造环境的A_2型花岗岩的特征;元素地球化学示踪指出,突泉地区碱性流纹岩可能起源于下地壳的部分熔融,结合区域上分布的同时代火山岩及A型花岗岩类,可以限定碱性流纹岩形成于伸展构造背景,并可能与北部蒙古-鄂霍茨克缝合带的演化有关。锆石Hf同位素研究显示,本区早白垩世流纹岩ε_(Hf)(t)值为+4.2～+10.7,其二阶模式年龄平均为0.74～0.76Ga,结合松嫩地块、兴安地块Hf同位素资料,表明兴安地块与松嫩地块具有相似的地壳增生过程。  相似文献   

非连续子母块体理论模型研究(Ⅰ):基本理论   总被引：1，自引：1，他引：0  

王士民  朱合华  蔡永昌 《岩土力学》2010,31(7):2088-2094

对节理岩体的非连续变形与破坏失稳的数值模拟分析是目前岩土力学与工程领域中的前沿课题之一,岩体由节理裂隙以及由其切割而成岩石块体组成,介于连续与非连续之间,由于其内部结构的不确定性造成了其宏观力学行为的复杂性。在讨论了岩体破坏失稳的研究尺度的基础上,从多尺度耦合的角度出发,同时考虑连续问题、非连续问题以及连续问题向非连续问题转化,提出了非连续子母块体理论模型。在非连续子母块体理论模型中,假定岩体与岩体内部被层理、节理等结构面所切割而成的岩石块体均属于宏观尺度,把宏观的岩石块体定义为母块体,用假想的人工节理将其继续分为若干更小的块体,更小的块体称为子块体,子块体为各向同性的均质体,并且在计算中不再发生破坏分解为更小的块体,作为计算分析的基本单元,子块体的研究尺度属于细观尺度。模型也重新定义了子块体间的接触,并将其划分为连续接触与非连续接触两种类型,连续接触在一定条件下发生破坏转化为非连续接触;采用增广拉格朗日乘子法对子块体间的接触进行处理,能够计算出准确的弹簧接触力。  相似文献   

节理网络模拟的程序实现及其在地下洞室中的动态响应分析     

贾超  王志鹏  朱维申 《岩土力学》2011,32(9):2867-2872

随着岩体工程的日益发展,人们愈发认识到岩体裂隙发育情况对工程影响的重要性,而岩体节理裂隙网络模拟是研究该类问题的重要手段。基于节理网络模拟结果,建立岩体力学分析模型,然后开展进一步的数值计算分析,在岩体工程中具有良好的发展前景。在岩体结构统计理论的基础上,自行编制了节理岩体裂隙网络模拟分析程序,直观再现了岩体内部的节理分布情况;将程序生成的可执行数据文件与离散元软件相融合;以含节理岩体的地下洞室为例,分别计算了静力和地震荷载作用下地下洞室围岩在不同时段的应力及位移变化情况。计算方法与结果对含节理岩体地下洞室围岩变形和破坏机制以及抗震工程设计具有指导意义  相似文献   

Finite element ana lysis for blasting law of jointed rock mass     

YU Qingyang  NIE Lei  ZHOU Nengjuan 《世界地质(英文版)》2009,12(4):210-214

On the basis of Mises strength theory, rock models are built including vertical, horizontal and diagonal joints to simulate jointed rock mass under blasting load by using FEM. The dynamic procedures of jointed rock mass under blasting are quantified and the effective stress-time curves of typical elements are compared to analyze the barrier of joints to the stress wave. The blasting law was studied according to the process of computer simulation and the effect of blasting, and some suggestions were given for solving the problems of overbreak and underbreak.  相似文献   

An anisotropic strength criterion for jointed rock masses and its application in wellbore stability analyses     

X. Chen  Q. Yang  K. B. Qiu  J. L. Feng 《国际地质力学数值与分析法杂志》2008,32(6):607-631

In this paper, an anisotropic strength criterion is established for jointed rock masses. An orientation distribution function (ODF) of joint connectivity, is introduced to characterize the anisotropic strength of jointed rock masses related to directional distributed joint sets. Coulomb failure condition is formulated for each plane of jointed rock masses by joint connectivity, where the friction coefficient and cohesion of the jointed rock mass are related to those of the intact rock and joint and become orientation dependent. When approximating joint connectivity by its second‐order fabric tensor, an anisotropic strength criterion is derived through an approximate analytical solution to the critical plane problem. To demonstrate the effects of joint distribution on the anisotropic strength of jointed rock masses, the failure envelopes are worked out for different relative orientations of material anisotropy and principal stress axes. The anisotropic strength criterion is also applied to wellbore stability analyses. It is shown that a borehole drilled in the direction of the maximum principal in situ stress is not always the safest due to the anisotropic strength of the jointed rock mass. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

基于Hoek-Brown准则的节理岩体能量参数估算          下载免费PDF全文

柴波  陶阳阳  杜娟  台大平  王禹 《地质科技通报》2020,39(1):78-85

岩体变形和破坏可以看作能量耗散和释放的过程.由于节理岩体结构复杂且难以开展室内试验,因此无法通过试验直接求取其能量学参数.基于Hoek-Brown准则和岩石能量理论,提出了节理岩体在临界状态能量学参数的估算方法.针对含贯通节理(或层面)岩体,通过修正岩块单轴抗压强度以体现贯通节理的方向效应.采用PFC3D分别模拟小尺寸岩样(Φ50mm×100mm)和大尺寸岩体(Φ2m×2m)的三轴压缩试验,通过岩石三轴试验结果拟合岩石数值模拟的细观参数并应用于节理岩体的模拟.根据节理岩体模拟得到应力应变曲线和能量流,验证了Hoek-Brown准则对节理岩体能量参数估算的合理性.  相似文献   

太平洋中部柱状沉积物中的自生矿物   总被引：2，自引：0，他引：2  

卢效珍 《海洋地质与第四纪地质》1992,12(1):67-72

根据《海洋四号》861—881航次获得的岩心资料,通过对沉积物类型的观察,对其中的几种自生矿物钙十字沸石、蒙脱石、重晶石、微结核、非晶质SiO_2等矿物的成因和与沉积物类型的相关性进行了探讨。  相似文献   

Generation of Late Cretaceous silicic rocks in SE China: Age, major element and numerical simulation constraints   总被引：2，自引：0，他引：2  

Cheng-Hong Chen  Chi-Yu Lee  Hsueh-Yu Lu  Pei-Shan Hsieh 《Journal of Asian Earth Sciences》2008,31(4-6):479-498

Rhyolite-dominating bimodal volcanic suites (rhyolite/basalt), mafic dikes and A-type granites distribute from N Zhejiang to S Fujian over 800 km in the Southeast Coast Magmatic Belt (SCMB) – the Late Yanshanian (LY) orogenic belt in SE China. Data of ⁴⁰Ar/³⁹Ar and K–Ar whole-rock ages and LA-ICPMS U–Pb zircon ages indicate that rhyolitic volcanism (101–72 Ma) is contemporaneous with the A-type granitic intrusions (100–90 Ma) and mafic dike injections (94–77 Ma). This time span is used to define the upper volcanic series in Zhejiang–Fujian areas. One striking feature of rhyolites in the SCMB is that many are strongly peraluminous (SP) and others, mostly restrict in Fujian, are peralkaline to mildly peraluminous (P-MP) and chemically resemble A-type granites. The SP character is unique among well-known large rhyolite provinces worldwide. Based on experimental works for a common thermal regime and inherited zircon age information, we suggest that SP and P-MP rhyolites represent low pressure melting of the felsic (quartzofeldspathic) granite (±metapelite) and the accompanied granodioritic, tonalitic and trondhjemitic member of the core complex assemblage, respectively, to account for the decreasing aluminosity. They could have also been contaminated by young igneous rocks, and ancient crust to a lesser degree, during ascent to the surface. Plate subduction and lithosphere extension processes, respectively, are numerically simulated for the magma generation of these rhyolites using the mafic underplating model. Results suggest that the most effective controlling factor to generate SP and associated P-MP (A-type) magmas during 95–80 Ma is thinning of the lithosphere thickness with a high exhumation rate. Under this circumstance, the core complex assemblage can be uplifted to lower level of the crust and match the constraint of experimental works.  相似文献   

Petrology of volcanic products younger than 42 ka on the Lipari–Vulcano complex (Aeolian Islands, Italy): an example of volcanism controlled by tectonics     

A. Gioncada  R. Mazzuoli  M. Bisson  M. T. Pareschi 《Journal of Volcanology and Geothermal Research》2003,122(3-4):191-220

Over the last 42 ka, volcanic activity at Lipari Island (Aeolian Arc, Italy) produced lava domes, flows and pyroclastic deposits with rhyolitic composition, showing in many cases evidence of magma mixing such as latitic enclaves and banding. In this same period, on nearby Vulcano Island, similar rhyolitic lava domes, pyroclastic products and lava flows, ranging in composition from shoshonite to rhyolite, were erupted. As a whole, the post-42 ka products of Lipari and Vulcano show geochemical variations with time, which are well correlated between the two islands and may correspond to a modification of the primary magmas. The rhyolitic products are similar to each other in their major elements composition, but differ in their trace element abundances (e.g. La ranging from 40 to 78 ppm for SiO₂ close to 75 wt%). Their isotopic composition is variable, too. The ⁸⁷Sr/⁸⁶Sr (0.704723–0.705992) and ¹⁴³Nd/¹⁴⁴Nd (0.512575–0.512526) ranges partially overlap those of the more mafic products (latites), having ⁸⁷Sr/⁸⁶Sr from 0.7044 to 0.7047 and ¹⁴³Nd/¹⁴⁴Nd from 0.512672 to 0.512615. ²⁰⁶Pb/²⁰⁴Pb is 19.390–19.450 in latites and 19.350–19.380 in rhyolites. Crystal fractionation and crustal assimilation processes of andesitic to latitic melts, showing an increasing content in incompatible elements in time, may explain the genesis of the different rhyolitic magmas. The rocks of the local crustal basement assimilated may correspond to lithotypes present in the Calabrian Arc. Mixing and mingling processes between latitic and rhyolitic magmas that are not genetically related occur during most of the eruptions. The alignment of vents related to the volcanic activity of the last 40 ka corresponds to the NNW–SSE Tindari–Letojanni strike-slip fault and to the correlated N–S extensional fault system. The mafic magmas erupted along these different directions display evidence of an evolution at different P_H2O conditions. This suggests that the Tindari–Letojanni fault played a relevant role in the ascent, storage and diversification of magmas during the recent volcanic activity.  相似文献