采空侧巷道底鼓形成机制与防治技术研究   总被引：2，自引：1，他引：1  

初明祥  王清标  夏均民 《岩土力学》2011,32(Z2):413-417

煤矿深部采空侧巷道底鼓现象日趋普遍和严重,严重影响巷道的运输和正常使用,其底鼓防治技术研究已成为目前煤矿岩石力学问题研究的重点。通过理论分析、数值模拟、现场试验等研究方法,对采空侧巷道底鼓的特征、形成原因、形成机制及其防治技术进行了详细研究,得到以下结论:(1)采空侧巷道底鼓与底板岩性和底板岩层的应力重新分布有关;(2)底板在严重挤压变形的情况下发生断裂,底板隆起,墙角发生外移是造成底鼓的主要原因;(3)底鼓始于巷道底角与底板中部;(4)采用中空锚杆注浆与高强锚杆锚注联合支护技术能有效治理采空侧巷道的底鼓。  相似文献   

有限元与改进单纯形法联合编程技术在位移反分析中的应用   总被引：1，自引：0，他引：1  

肖铭钊  周承豪  程芸  冯晓腊  杨俊梅 《岩土力学》2011,32(3):899-904

根据弹性地基梁法基本思想,考虑基坑分步开挖和逐级加撑的动态施工因素,通过有限元计算模拟基坑实际开挖过程。结合现场监测数据,采用位移反分析方法反演各土层m值,并准确预测后续工况支护体的变形。采用有限元通用软件ANSYS内嵌的APDL语言编程建立支护体有限元计算模型,并应用数学软件MATLAB编制"改进单纯形法"优化程序,编写了接口程序,实现了MATLAB对ANSYS模型的实时循环调用和逐步寻优。武汉长江隧道武昌明挖段基坑工程算例证明,基于单纯形法的联合编程技术能方便、高效地被应用于支护体位移反分析预测中。建立了基于本工况预测下一工况或相邻断面的扩展型位移反分析预测模型,预测结果与实测结果拟合程度较高。  相似文献   

节理岩体等效损伤流变模型初步研究   总被引：1，自引：0，他引：1  

黄耀英  郑宏 《岩土力学》2011,32(12):3566-3570

对节理岩体等效损伤流变模型进行了初步研究,假设岩石为各向同性体各向同性损伤,节理面的法向和切向损伤不同,分别建立了岩石和节理面流变损伤演变函数。假设材料无损,计算应力采用有效应力,推导了节理岩体等效损伤流变模型有限元计算公式,编制了相应的有限元程序。算例分析表明,采用的节理岩体等效损伤流变模型是可行的,可较好地反映节理岩体的损伤演变过程。  相似文献   

新疆阿尔泰康布铁堡组钾质和钠质流纹岩的成因及同位素年代学研究   总被引：10，自引：2，他引：8  

单强  曾乔松  罗勇  杨武斌  张红  裘瑜卓  于学元 《岩石学报》2011,27(12):3653-3665

阿尔泰南缘康布铁堡组酸性火山岩分布在麦兹、克朗、冲呼尔以及阿舍勒等火山-沉积盆地.本文对其中的钾质流纹岩(TM1,铁木尔特地区)和钠质流纹岩(KK7,可可塔勒地区)进行了SHRIMP锆石U-Pb定年以及地球化学的研究.钾质流纹岩的年龄为400.8±8.4Ma(加权平均年龄为394.8±7.9Ma),钠质流纹岩的年龄为402.2±6Ma(加权平均年龄为396.8±5.1Ma).主元素分析结果证明研究区在时间和空间上紧密共生的高钾流纹岩和高钠流纹岩同属于高碱、高硅、低钙、过铝质的钙碱性岩系.相似的稀土元素分配模式和同样亏损高场强元素(Ti、Nb、Ta)的地球化学特征暗示二者的原始岩浆源于上地壳部分熔融.钾质流纹岩富集Rb,Ba、Pb,钠质流纹岩则富集Sr,这种元素分相富集的特征符合在岩浆液态不混溶条件下微量元素在共轭钠质熔体和钾质硅酸盐熔体中的分配原则.由此推论,本区产出的钾质流纹岩和钠质流纹岩可能是上地壳部分熔融形成的高挥发分酸性岩浆液态不混溶的产物.  相似文献   

西藏羌塘南缘热那错早白垩世流纹岩锆石U-Pb年代学和Hf同位素及其意义   总被引：8，自引：2，他引：6  

常青松  朱弟成  赵志丹  董国臣  莫宣学  刘勇胜  胡兆初 《岩石学报》2011,27(7):2034-2044

在青藏高原的演化历史中,班公湖-怒江洋的俯冲方向一直存在争议。现有的岩浆作用时空展布表明,大量早白垩的岩浆作用分布在班公湖-怒江缝合带(以下简称为班怒带)以南,但是近年来在该缝合带以北也发现了少量同时代的岩浆作用。本文研究了靠近班公湖-怒江蛇绿岩带以北、改则县北部热那错地区的流纹岩,获得了岩石的锆石U-Pb年龄和Hf同位素成分。热那错流纹岩年龄为~110Ma,与相邻地区报道的岩浆岩活动和缝合带以南的北拉萨地体地区大范围出露的早白垩世岩浆岩同期产出。岩石具有不均一且偏正的ε_Hf(t)特征,与北拉萨地体同期岩浆岩Hf同位素成分相似。本文综合考虑了班怒带两侧发育同期岩浆活动、且南侧极大量而北侧很少量发育的特征,认为热那错流纹岩的成因可以置于班公湖-怒江洋向南俯冲的总体模式中,南向俯冲的班公湖怒江岩石圈在~110Ma发生板片断离,可以同时解释分布于缝合带两侧的早白垩世岩浆活动。  相似文献   

Three dimensional numerical simulation of residential building on shrink–swell soils in response to climatic conditions          下载免费PDF全文

Xiong Zhang  Jean‐Louis Briaud 《国际地质力学数值与分析法杂志》2015,39(13):1369-1409

Shrink–swell soils can cause distresses in buildings, and every year, the economic loss associated with this problem is huge. This paper presents a comprehensive system for simulating the soil–foundation–building system and its response to daily weather conditions. Weather data include rainfall, solar radiation, air temperature, relative humidity, and wind speed, all of which are readily available from a local weather station or the Internet. These data are used to determine simulation flux boundary conditions. Different methods are proposed to simulate different boundary conditions: bare soil, trees, and vegetation. A coupled hydro‐mechanical stress analysis is used to simulate the volume change of shrink–swell soils due to both mechanical stress and water content variations. Coupled hydro‐mechanical stress‐jointed elements are used to simulate the interaction between the soil and the slab, and general shell elements are used to simulate structural behavior. All the models are combined into one finite element program to predict the entire system's behavior. This paper first described the theory for the simulations. A site in Arlington, Texas, is then selected to demonstrate the application of the proposed system. Simulation results are shown, and a comparison between measured and predicted movements for four footings in Arlington, Texas, over a 2‐year period is presented. Finally, a three‐dimensional simulation is made for a virtual residential building on shrink–swell soils to identify the influence of various factors. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

The rare earth element (REE) mineralisation potential of highly fractionated rhyolites: A potential low-grade,bulk tonnage source of critical metals     

《Ore Geology Reviews》2017

The rare earth elements (REE) have become crucial for modern industry, technology and medicine, with the increase in demand for these elements over the past few years currently being met by relatively few well-known mineral deposits. This lack of a secure supply of the REE has led to increased research into potential alternative sources of these in demand elements. The primary fractionation processes involved in the petrogenesis of highly fractionated high-silica rhyolites can cause the magmas that form these units to become preferentially enriched in the REE, especially in the more valuable heavy REE (HREE), although this is dependent on the mineral assemblages fractionated by the system in question, a factor that is in turn a function of the source and tectonic setting of a given magmatic event. The mineralogy of the REE is also important, with volatile exsolution and vapour-phase activity within highly evolved rhyolite systems potentially having a key role in concentrating the REE and other elements into concentrations (and more importantly potentially acid leachable and therefore processable minerals) that may be economically viable to extract. This, combined with the fact these rhyolites are often enriched in other critical and/or economically important metals (e.g., Y, Nb, Ta, Be, Li, F, Sn, Rb, Th, and U) means that these volcanic units should be considered as potential sources of these critical metals. In addition, the large volume nature of these rhyolites combined with the fact they frequently crop out at the Earth’s surface makes them ideally suited for more economical bulk open pit extraction. This suggests that these high-silica REE-enriched rhyolites should be considered potential REE analogues of bulk-tonnage, low-grade porphyry Cu deposits, warranting further investigation to determine whether these rhyolites are a viable new source of the REE (especially the HREE) and are potential targets for future mineral exploration.  相似文献   

Stability analysis of tunnels driven in jointed rocks by means of a homogenized limit analysis approach     

Samir Maghous  José E. B. Winiawer  Vanessa F. Pasa Dutra 《国际地质力学数值与分析法杂志》2014,38(18):2009-2032

Conceived as a potential alternative to the classical design methods employed for analyzing the stability of underground structures driven in jointed rocks, the homogenization approach stems from the heuristic idea that, from a macroscopic point of view, a rock mass cut by a network of joints may be perceived as a homogenized continuum. The strength properties of the latter can be theoretically obtained from the failure conditions of its individual constituents: rock matrix and joint interfaces. At the material level, the limit analysis reasoning is used in the context of homogenization to formulate the homogenized strength criterion of a jointed rock mass in the particular situation of a single set of parallel joints. As it could be expected, the obtained closed‐form expressions show the strength anisotropy induced by joint preferential orientation. The support functions (π functions) associated with the homogenized strength criterion are also determined in both plane strain and three‐dimensional cases. This criterion is then applied to the investigation of stability analysis of a tunnel excavated in a jointed rock mass. Upper bounds estimated of the stability factor are derived from the implementation of the kinematic approach directly on the homogenized underground structure. Finally, the approach is applied to analyze and discuss the collapse of the Pinheiros subway station (São Paulo, Brazil). Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Investigation on strength and stability of jointed rock mass using three‐dimensional numerical manifold method     

L. He  X. M. An  X. B. Zhao  Z. Y. Zhao 《国际地质力学数值与分析法杂志》2013,37(14):2348-2366

This paper proposes a numerical model for jointed rock masses within the 3‐D numerical manifold method (NMM) framework equipped with a customized contact algorithm. The strength of rock sample containing a few sets of discontinuities is first investigated. The results of models with simple geometries are compared with the available analytical solutions to verify the developed computer code, whereas models with complex geometries are simulated to better understand the fundamental behavior and failure mechanism of jointed rock mass. Furthermore, the stability of jointed rock mass in an underground excavation is studied, where rock failure process is determined by the 3‐D NMM simulation. The simulation results provide valuable guidance on excavation process design and stabilization design in rock engineering practice. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Early Cretaceous K-rich rhyolites from the Duolong Cu–Au deposit,southern Qiangtang,China: evidence for crustal growth     

Wei Wang  Cai Li  Jian-Jun Fan  Wei Xu  Yu-Chao Dong 《International Geology Review》2018,60(9):1098-1115

We report new zircon U–Pb age, Hf isotopic, and major and trace element data for rhyolites from the Duolong Ore Concentration Area of the Southern Qiangtang Terrane. Building on previous studies, we constrain the tectonic setting and propose a model to explain the geodynamics and crustal growth during regional magmatism in the Early Cretaceous. The analysed rhyolites yield laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) zircon U–Pb ages of 115 and 118 Ma. The rocks are K-rich (K₂O = 6.66–9.93 wt.%; K₂O/Na₂O = 8.2–19.7 wt.%), alkaline and peraluminous (A/CNK = 1.02–1.46), and are characterized by high SiO₂ contents (72.8–78.8 wt.%) similar to highly fractionated I-type granites. Fractionation of Fe–Ti oxides, plagioclase, hornblende, Ti-bearing phases, apatite, monazite, allanite and zircon contributed to the variations in major and trace element chemistry. High K₂O contents are likely due to partial melting of the continental crust. The samples have positive zircon εHf(t) values ranging from +7.1 to +11.2. These features, together with young zircon Hf crustal model ages of 489–721 Ma, indicate that the K-rich rhyolites were derived from juvenile lower crust with an input of a mantle-derived component. We suggest that the Early Cretaceous K-rich rhyolites formed in a continental arc setting during northward subduction of Bangong Co–Nujiang oceanic lithosphere. Basaltic magma underplating was responsible for vertical crustal growth, triggered by slab roll-back in the Duolong Ore Concentration Area in the Early Cretaceous.  相似文献