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采用无限元作为岩体地下洞室静动力分析的边界条件,建立了岩体地下洞室的静动力有限元一无限元(FE-IE)计算模型,分析了柔性垫层对水电站厂房这类大型岩体洞室结构的减震效果.研究结果表明:柔性垫层虽未能从根本上改变岩体洞室结构的地震响应,但是设置一定厚度的柔性垫层后不仅能充分发挥岩体洞室围岩的自承能力,而且还能明显地减小混... 相似文献
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基于Fourier-Bessel级数展开法,研究深埋圆形三层复合式衬砌洞室在平面P波入射下的动应力集中问题,并给出三层衬砌洞室动应力集中系数级数解析解;依托某IX度地震区管道隧道实际工程,分析不同衬砌刚度组合和厚度组合对洞室动应力集中系数的影响。研究表明:注浆加固洞室围岩和设置减震层都可以降低二次衬砌动应力集中系数;增大围岩注浆区弹性模量和厚度,有利于减小衬砌动应力集中系数,最优围岩注浆区厚度为1倍洞室净空半径;减震层弹性模量降低,减震层厚度增大,二次衬砌动应力集中系数变小,减震层弹性模量宜低于围岩弹模1/20,最优减震层厚度宜取1/50的洞室内净空半径。最后针对实际管道隧道抗减震技术,考虑围岩稳定性,提出"围岩-加固圈-减震层-衬砌"新型减震结构,分析结果表明:对比其他三种抗减震措施,新型减震结构的减震效果最好。 相似文献
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受结构和赋存环境的制约,岩体力学性质及其力学参数具有显著的时间和空间变异性.岩体力学参数和岩体质量从不同的侧面反映了岩体力学性质,两者具有必然的关联性,故可用相对简单的岩体质量评价来选取岩体力学参数:按地质条件将岩体空间离散为若干连续微元体单元;采用Q、RMR和BQ等方法逐一对各单元开展岩体质量评价,并利用岩体质量与岩体力学参数间的关系(如Hoek-Brown经验准则)计算其力学参数;综合各单元的计算结果确定反映连续岩体空间内空间变异特征的力学参数.以某水电站地下洞室群为例,实现了工程区围岩力学参数的不连续取值. 相似文献
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大足石刻北山168窟为五百罗汉窟,开凿于1119年至1125年,窟高3.3m,宽3.14m,进深7.1m,是大足石刻中尺寸较大的一个重要洞窟。目前,168窟围岩裂隙风化病害十分严重,面临失稳坍塌的危险。为制定针对性的长久保护措施,需查明168窟围岩病害的现状。通过现场调查、物探、钻探等技术手段,获取了大足石刻北山168窟及邻近区域的工程地质条件。进一步,采用高频瑞雷波探测技术对168窟顶板岩体进行瑞雷波相速度成像,考虑168窟顶板岩体特定的围岩边界条件和场地工程地质条件,对洞窟顶板岩体瑞雷波相速度-深度成像剖面中的低速区分布进行成因分析和解译,揭示石窟顶板岩体风化现状和节理裂隙的发育情况。为分析评价洞窟围岩稳定性和石窟保护工程设计提供基础性地质资料和必要的计算参数,也为相关技术在文物保护工程的应用提供经验和借鉴。 相似文献
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目前,地下工程围岩尤其是大型岩石地下工程围岩的粘弹塑性分析研究少见报道。针对这种情况,本文根据西原粘弹塑性流变模型相关理论开发了hhu-vp流变计算软件,以用于大型岩石地下工程围岩粘弹塑性流变数值模拟分析;并以一简单算例与软件FLAC-3D比较,结果偏差在容许范围内。将其应用于水布垭大型地下洞室围岩流变研究中,对该地下洞室的施工开挖及支护处理过程进行了模拟,提出了支护处理意见,并对其运营期的长期稳定性作出了评价。 相似文献
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深部岩体处于"三高"环境下,表现出不同于浅埋岩体的性质,其变形破裂规律更为复杂(分区破裂、片帮、塑性流动、岩爆等),为了准确描绘深部隧道围岩变形破裂规律,采用PFC从微观角度研究深部岩体的宏观响应。研究发现:随着隧道埋深增加,压力增大,由浅部围岩表面塑性破坏变为深部围岩破裂扩展,破裂区域呈交替分区破裂向深部发展,破裂区的间距与岩性和埋深有关;从横断面看,拱腰先出现破裂,然后拱脚出现破裂,最后贯通形成破裂区;若围岩表面施加外力,破裂区域减小,分区向深部移动,因此预应力锚杆有效地改善了围岩承载特性;研究结果与模型试验吻合,符合深部岩体卸荷作用下的变形破坏规律。结论可为深部岩体工程设计施工提供参考。 相似文献
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Guo Qiliang 《中国地震研究》2007,21(3):345-354
The hydrofracturing technique has developed into a reliable and practical method for determining the original three-dimensional crustal stress state of underground caverns,the load-bearing capacity of a high pressure cavern itself,and the high pressure hydraulic permeability of rock masses,and has also been extensively used in disposal of nuclear waste,long and deeply-buried traffic channels and high-pressure cavern engineering for hydraulic power plants.The practice shows that the comprehensive measurement of the physical parameters of the rock mass and taking full use of the wall rock load-bearing capacity to optimize the engineering design hold are very useful in ensuring the engineering safety and improving the design level. 相似文献
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本文根据岩体力学性质的各向异性，以岩体正交异性弹性理论为基础，提出用水力压裂法测算水平方向两主应力大小和方向的原理及测量有关岩体弹性参数的方法。 相似文献
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Xiaorong Luo 《Earth and Planetary Science Letters》2002,201(2):431-446
Natural hydrofracturing caused by overpressure plays an important role in geopressure evolution and hydrocarbon migration in petroliferous basins. Its mechanism is quite well understood in the case of artificial hydraulic fracturing triggered by high-pressure fluid injection in a well. This is not so for natural hydraulic fracturing which is assumed to initiate as micro-cracks with large influence on the permeability of the medium. The mechanism of natural hydraulic cracking, triggered by increasing pore pressure during geological periods, is studied using a fracturing model coupled to the physical processes occurring during basin evolution. In this model, the hydraulic cracking threshold is assumed to lie between the classical failure limit and the beginning of dilatancy. Fluid pressure evolution is calculated iteratively in order to allow dynamic adjustment of permeability so that the fracturing limit is always preserved. The increase of permeability is interpreted on the basis of equivalent fractures. It is found that fracturing is very efficient to keep a stress level at the rock’s hydraulic cracking limit: a fracture permeability one order of magnitude larger than the intrinsic permeability of the rock would be enough. Observations reported from actual basins and model results strongly suggest that natural hydraulic cracking occurs continuously to keep the pressure at the fracturing limit under relaxed stress conditions. 相似文献
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ABSTRACT The intended performance of hydraulic structures such as dams built on soluble rock or soil foundations may depend upon rates of dissolution caused by water seeping through joints, fissures or granular zones. Previous papers by one author and collaborators have defined the rates of dissolution for soluble rocks by means of a simple equation: dM/dt = K A (Cs—C)θ. This relationship may be used as an aid to prediction of enlargement of joints and fissures in rocks, settlements of granular foundation strata, the deterioration of filters, risks to shallow but intensely loaded foundations, and durability of underground storage caverns in soluble rocks. The relationship requires a knowledge of the solution potentials of groundwater associated with these features of engineering structures. They in turn require an understanding of the relevant hydrochemistry and hydrology which is discussed in this paper. 相似文献
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地质条件对隧道的地震响应的影响因素研究,目前已有较多研究者开展,但多数研究者关注单因素研究,但对多因素及各因素间相互作用关注较少。本文以华丽高速公路典型隧道为工程背景,将其抽象为数值算例,并基于正交设计及均匀设计等试验方法,分别研究地质条件中岩体的力学效应、应力状态效应、结构面的力学效应对隧道的影响。研究结果表明:对于岩体力学参数,除开挖变形指标的主要影响因素为变形模量外,岩体力学参数中对隧道地震响应最主要的影响因素为黏聚力及内摩擦角,即强度参数;岩体应力状态参数中对隧道地震响应最主要的影响因素为隧道埋深,其次分别为平面内侧压系数和平面外侧压系数;节理力学参数中的摩擦角和抗拉强度为影响隧道地震响应的主要因素,其次为黏聚力、法向刚度、切向刚度。 相似文献
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《Journal of Applied Geophysics》2007,61(1):1-15
The presence of an excavation disturbed zone (EDZ) around an excavation boundary can significantly affect the overall performance of the excavation and the general safety of men and equipment. Hence, it has been an important subject of research in various rock excavation projects. The EDZ is generally defined as the rock zone beyond the excavation boundary where the physical, mechanical and hydraulic properties of the rock have been significantly affected due to the excavation and redistribution of stresses. For LKAB's Kiirunavaara underground iron ore mine in Sweden, the understanding of the EDZ is essential for optimal design of rock support. With this main objective an EDZ investigation was conducted at the mine using seismic measurement techniques. Cross-hole seismics and spectral analyses of surfaces waves (SASW) were the main techniques used. Borehole Image Processing Systems (BIPS) complemented the seismic measurements. The results show that an EDZ with a thickness of 0.5–1. 0 m existed behind the boundaries of the mining drifts being investigated. The magnitude of the Young's modulus of this zone was 50% to 90% of that of the undisturbed rock. 相似文献
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The transmission of seismic waves in a particular region may influence the hydraulic properties of a rock mass, including permeability, which is one of the most important. To determine the effect of a seismic wave on the hydraulic behavior of a fractured rock mass, systematic numerical modeling was conducted. A number of discrete fracture network(DFN) models with a size of 20 m × 20 m were used as geometrical bases, and a discrete element method(DEM) was employed as a numerical simulation tool. Three different boundary conditions without(Type Ⅰ) and with static(Type Ⅱ) and dynamic(Type Ⅲ) loading were performed on the models, and then their permeability was calculated. The results showed that permeability in Type Ⅲ models was respectively 62.7% and 44.2% higher than in Type I and Type Ⅱ models. This study indicates that seismic waves can affect deep earth, and, according to the results, seismic waves increase the permeability and change the flow rate patterns in a fractured rock mass. 相似文献
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A typical fractured rock mass is intersected by several sets of discontinuities, which provide the main flowpath for ground water. Due to the limitations of data obtained by conventional field measurements, it is often difficult to estimate the anisotropic permeability tensor associated with the joints existing in the rock mass. For that reason, determining permeability tensors for fractured rocks is an important topic in rock mass hydraulics. Based on field surveys, joint parameters can be analyzed by using probabilistic and statistical tools, and three-dimensional mapping of the jointed rock mass. Through analysis of a single joint's hydraulic characteristics, the principal value of the permeability tensor for the jointed rock mass can be determined by using Monte Carlo methods and the searching percolation trace method, which is developed in this paper. The study reports on practical examples demonstrating that results from the methods discussed in this paper are in agreement with those from field hydrogeological surveys and measurements. 相似文献
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以2018年"8·11"大安山反倾岩质崩塌为研究对象,通过对大安山地区区域性节理、崩塌及斜坡结构、危岩体变形特征等进行调查研究,运用水力劈裂理论,剖析大安山崩塌机制。研究结果表明:在区域性节理和差异性风化共同作用下,大安山地区发育大量高20~50 m高陡反倾岩质斜坡,为崩塌灾害发生提供充分条件;同时,节理裂隙网络与强硬岩层的空间组合为降雨入渗、运移、储藏提供了良好的地质条件,当遭遇降雨时,雨水沿岩体裂隙渗流并充满裂隙,在降雨停止后短期内,裂隙受高水头作用仍发生水力劈裂,致使裂隙发生扩展贯通,并最终导致危岩体失稳崩塌。 相似文献
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Coesite has been found in a metasedimentary rock in a continental unit of the Western Alps (Dora Maira massif). The rock preserves the high-pressure, low-temperature assemblage of nearly pure pyrope-talc-phengite-kyanite in a quartz matrix; coesite exclusively occurs as inclusions in pyrope and is partly inverted to quartz. Textural observations and mechanical considerations suggest that the rock crystallised in the coesite stability field. A simple elastic model for a coesite inclusion in pyrope explains why coesite has been exclusively preserved in the inclusions and not in the matrix. Combined with petrological data the model constrains the crystallisation conditions of the pyrope-coesite rock (P > 28kbar, 650 < T < 830°C) and possible uplift paths. The paths derived suggest a mechanism of rapid decompression without any temperature increase, which must be related to tectonic processes.
This finding has an important bearing on the significance of P-T conditions estimated from minerals occurring as inclusions and on the actual behaviour of continental crust in collision zones. 相似文献