水压致裂技术测试底板岩体张开型临界应力强度因子     

郑纲  门玉明  靳德武 《煤田地质与勘探》2004,32(1):43-45

利用断裂力学进行突水判别,必须求出临界应力强度因子。由于岩体结构复杂,很难获取符合临界应力强度因子测试的岩样。文中对水压致裂技术进行了断裂力学解释,建立了断裂力学模型,应用叠加原理推导了临界应力强度因子的计算公式。并应用这一结果,对葛店煤矿水压致裂测试底板原位地应力资料进行了分析,求得底板岩体的临界应力强度因子。   相似文献   

声波全波列测井在工程勘察中的应用     

周明磊  刘振祥  闫兴健  王克敏  许安鹏 《煤田地质与勘探》2004,32(1):57-59

近年来, 声波全波列测井在理论和仪器原理上已经成熟, 正被广泛应用在固体矿产测井及工程勘查设计中。本文介绍了全波列测井资料在这些应用中的解释技术, 使它能提供更多的信息, 解决更多的地质问题。   相似文献   

裂隙蠕变的稳定性准则   总被引：3，自引：1，他引：2  

杨松林  徐卫亚  张贵金 《岩土力学》2003,24(3):423-427

介绍了最小耗能原理及其建立材料强度准则的一般步骤,在强度准则通常为能量蓄积程度表达式这一前提下,从最小耗能原理出发,利用线粘弹性断裂理论推导了裂纹蠕变的稳定性准则。为对比起见,将线弹性断裂理论的应变能密度因子断裂判据直接推广到粘弹性状态,得到了与最小耗能原理相同的稳定性准则表达式,并分析了几种流变材料中裂纹蠕变的长期稳定性。  相似文献   

块裂结构岩质边坡水力学模型及数值模拟   总被引：5，自引：0，他引：5  

赵瑜  李晓红  卢义玉  靳晓光 《岩土力学》2005,26(6):995-999

把块裂结构岩质边坡看作拟连续介质与块裂介质广义双重介质,运用现代分形理论,建立了1-2级主干裂隙分形网络,并根据两类介质接触处水头相等及节点流量相等建立了合理的块裂结构边坡三维水力学模型,给出了有限元解法,模拟了三峡工程的蓄水位至175 m时边坡渗流场与应力场的变化,在应用上有较好的可靠性与广泛性。  相似文献   

岩石裂纹水力劈裂分析与临界水压计算   总被引：9，自引：1，他引：8  

李宗利  张宏朝  任青文  王亚红 《岩土力学》2005,26(8):1216-1220

水力劈裂是深埋隧洞施工涌水或高压隧洞洞周岩体开裂渗漏的重要因素之一,对其破坏机理研究是岩土工程界的热点课题。根据裂纹面的应力状态,从断裂力学角度将岩体的裂纹扩展分为拉剪复合断裂及压剪复合断裂。应用工程近似裂纹失稳准则,分别推导出两种破坏模式的临界水压计算公式,并对其随裂纹方向及地应力侧压系数变化规律进行分析。结果表明,当侧压力系数等于1.0时,临界水压并不随裂纹的方向而变化;在拉剪复合断裂模式下,裂纹与主应力方向平行时最易发生水力劈裂;在压剪复合断裂模式下,当压剪断裂参数与裂纹面间摩擦系数之差大于零时,其规律性与拉剪复合断裂模式基本一致;但当其差值小于零时,裂纹与最大主应力夹角呈45°及135°时最易发生水力劈裂。  相似文献   

断裂构造对山区公路隧道选线与施工的影响研究     

张涛  夏述光  谭显坤  周小飞  王元汉 《岩土力学》2005,26(Z2):275-278

断裂构造对于岩体的工程性质起着十分重要的作用。建设中的十漫 (十堰至漫川关) 高速公路,地处两郧断裂带穿越地区。结合该段最长的隧道——二道垭隧道左、右隧道不同围岩类别与特征,分析了两郧断裂带的影响。针对隧道不同围岩类别,探讨了不同的开挖和支护方法,并就其施工效率和成本进行了比较分析。研究成果表明, 断裂构造对隧道施工和稳定性有重要影响。高速公路选线应加强勘察,尽量避开断裂带,从而达到施工安全、迅速、经济的目的。  相似文献   

Capturing the two‐way hydromechanical coupling effect on fluid‐driven fracture in a dual‐graph lattice beam model          下载免费PDF全文

Ole Ivar Ulven  WaiChing Sun 《国际地质力学数值与分析法杂志》2018,42(5):736-767

Fluid‐driven fractures of brittle rock is simulated via a dual‐graph lattice model. The new discrete hydromechanical model incorporates a two‐way coupling mechanism between the discrete element model and the flow network. By adopting an operator‐split algorithm, the coupling model is able to replicate the transient poroelasticity coupling mechanism and the resultant Mandel‐Cryer hydromechanical coupling effect in a discrete mechanics framework. As crack propagation, coalescence and branching are all path‐dependent and irreversible processes, capturing this transient coupling effect is important for capturing the essence of the fluid‐driven fracture in simulations. Injection simulations indicate that the onset and propagation of fractures is highly sensitive to the ratio between the injection rate and the effective permeability. Furthermore, we show that in a permeable rock, the borehole breakdown pressure, the pressure at which fractures start to grow from the borehole, depends on both the given ratio between injection rate and permeability and the Biot coefficient.  相似文献   

Capturing the complete stress–strain behaviour of jointed rock using a numerical approach          下载免费PDF全文

Kamran Esmaieli  John Hadjigeorgiou  Martin Grenon 《国际地质力学数值与分析法杂志》2015,39(10):1027-1044

This paper presents the results of a series of numerical experiments using the synthetic rock mass (SRM) approach to quantify the behaviour of jointed rock masses. Field data from a massive sulphide rock mass, at the Brunswick mine, were used to develop a discrete fracture network (DFN). The constructed DFN model was subsequently subjected to random sampling whereby 40 cubic samples, of height to width ratio of two, and of varying widths (0.05 to 10 m) were isolated. The discrete fracture samples were linked to 3D bonded particle models to generate representative SRM models for each sample size. This approach simulated the jointed rock mass as an assembly of fractures embedded into the rock matrix. The SRM samples were submitted to uniaxial loading, and the complete stress–strain behaviour of each specimen was recorded. This approach provided a way to determine the complex constitutive behaviour of large‐scale rock mass samples. This is often difficult or not possible to achieve in the laboratory. The numerical experiments suggested that higher post‐peak modulus values were obtained for smaller samples and lower values for larger sample sizes. Furthermore, the observed deviation of the recorded post‐peak modulus values decreased with sample size. The ratio of residual strength of rock mass samples per uniaxial compressive strength intact increases moderately with sample size. Consequently, for the investigated massive sulphide rock mass, the pre‐peak and post‐peak representative elemental volume size was found to be the same (7 × 7 × 14 m). Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

Damage‐viscoplastic consistency model for rock fracture in heterogeneous rocks under dynamic loading     

Timo Saksala 《国际地质力学数值与分析法杂志》2010,34(10):1041-1062

This paper presents a damage‐viscoplastic consistency model for numerical simulation of brittle fracture in heterogeneous rocks. The model is based on a combination of the recent viscoplastic consistency model by Wang and the isotropic damage concept with separate damage variables in tension and compression. This approach does not suffer from ill‐posedness, caused by strain softening, of the underlying boundary/initial value problem since viscoplasticity provides the regularization by introducing a length scale effect under dynamic loading conditions. The model uses the Mohr–Coulomb yield criterion with the Rankine criterion as a tensile cut‐off. The damage law in compression is calibrated via the degradation index concept of Fang and Harrison. Thereby, the model is able to capture the brittle‐to‐ductile transition occurring in confined compression at a certain level of confinement. The heterogeneity of rock is accounted for by the statistical approach based on the Weibull distribution. Numerical simulations of confined compression test in plane strain conditions demonstrate a good agreement with the experiments at both the material point and structural levels as the fracture modes are realistically predicted. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Effect of NAPL exposure on the wettability and two‐phase flow in a single rock fracture          下载免费PDF全文

Hang Bok Lee  Byung‐Woo Kim 《水文研究》2015,29(23):4919-4931

Surface‐wetting properties are an important cause of changing the groundwater and two‐phase fluid flows. Various factors affecting the surface wettability were investigated in a parallel‐walled glass fracture with non‐aqueous phase liquid (NAPL) (gasoline, diesel, trichloroethylene, and creosote) wetted surfaces. First, the effect of the duration of NAPL exposure on wettability change was considered at pre‐wet fracture surfaces using the various NAPL species, and the result showed that the surface became hydrophobic after the exposure time of NAPL exceeded 2000 min. Second, the initial wetting state of the surface affected the timing when the wettability change begins as well as the extent of the wettability change in an NAPL‐wetted rock fractures. Under the dry condition, the wettability change was completed within a very short time of exposure to NAPL (~5 min), and then it finally reached the intermediate and weakly NAPL wetting (contact angle of 118°). Under the pre‐wet condition, a relatively long time of exposure (~5000 min) was needed to observe the obvious change of the surface wettability, which was changed up to strongly NAPL wetting (contact angle of 142°). Third, the wettability changed by NAPL exposure was stable and maintained for a long time, regardless of water flushing rate and temperature. Finally, the wettability change by the exposure of NAPL on parallel fracture surfaces was evaluated at various groundwater flow velocities. Result showed that groundwater flow velocity has an important impact upon measured contact angle. Although fracture surfaces were exposed to NAPL at the low groundwater flow velocity, the wettability was not changed from hydrophilic to hydrophobic when the contact time between NAPL and mineral surfaces was not sufficient owing to the pulse‐type movement of NAPL. This implies that the variation of exposure pattern due to groundwater flow on the wettability change can be an important factor affecting the wettability change of fracture surface and migration behaviour at natural fractured rock aquifers in case of NAPL spill. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献