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1.
岩体结构控制下的斜坡变形特征 总被引：4，自引：1，他引：3
为了分析岩体结构与斜坡变形的作用关系,以巴东城区为例,探讨了区内主要地层（三叠系巴东组第2段T2b2、第3段T2b3）岩体结构在内、外动力地质作用下的演化过程,进而分析了不同类型岩体结构控制下的表层斜坡的变形特征。结果表明：内动力地质作用过程中形成了岩体结构,而外动力地质作用改造着岩体结构;根据沉积成岩、构造作用过程中所形成层理、节理、劈理的发育程度,可将岩体划分为层状结构、块裂结构和碎裂结构;风化、水等外动力地质作用对岩体结构的改造结果受控于原岩结构;巴东组第3段层状岩体多沿层间软弱夹层顺层滑动;巴东组第2段互层状岩体,层间差异崩解作用易形成崩塌;结构面的组合关系、发育规模控制着块体失稳的形式和规模;密集发育的劈理将岩体分割呈碎裂状结构,卸荷松动下呈膝状弯曲。这些认识对巴东地区斜坡灾害分析、防治具有一定的指导意义。 相似文献
2.
A new method to evaluate the strength of rock mass structures is proposed and examined. The method is based on the collapse load analysis of elasto-perfectly plastic material along with the homogenization method, which enables the multi-scale analyses for heterogeneous media. The homogenization process replaces a rock mass with cracks by an equivalent continuum medium with macroscopic stiffness while the failure criterion for the rock mass is estimated in the localization process. It is shown that both the averaged stiffness and the macroscopic failure criterion of the discontinuous rock mass are numerically obtained via the finite element analyses. Thus, the failure strength of a rock mass structure is evaluated by the collapse load analysis in the form of Linear Programming with the macroscopic failure criterion. This is the first attempt to apply the homogenization method to the strength analysis of rock mass. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
3.
金华山软岩铁路隧道施工过程围岩屈服接近度分析 总被引：1，自引：0，他引：1
隧道施工过程中围岩处于复杂应力状态下,隧道围岩屈服区演化特征的确定对于围岩稳定性分析和开挖支护方案优化具有重要的意义。采用屈服接近度指标衡量围岩破坏接近程度可以合理地描述复杂应力状态下围岩的应力危险性,对Mohr-Coulomb类岩体材料的屈服接近度函数进行了相应的推导,并在非线性有限元用户子程序上编程予以实现。介绍了赣州-龙岩铁路DKl33+095～DKl38+237段软弱围岩单线隧道正台阶步施工方案以及湿喷纤维混凝土支护方案。为了对该隧道施工过程中隧道围岩屈服区的演化特征进行合理评价,采用非线性有限元法对软弱围岩条件下的铁路隧道施工过程进行了数值模拟,分析了施工过程中隧道围岩屈服接近度分布特征,判定了隧道台阶步施工过程中隧道围岩的稳定性。分析结果表明:该隧道施工过程中围岩破坏区主要发生在下台阶步施工过程中;屈服接近度指标比传统的塑性区分布提供的信息更加丰富,有利于工程技术人员定量地评价隧道开挖支护方案。 相似文献
4.
我国西南高山峡谷地区,常发生高位岩质斜坡失稳,形成碎屑流,造成巨大人员伤亡与经济财产损失。目前存在着许多关于岩质滑坡的研究理论和物理模型,但这些理论与模型都忽略了岩体结构这一属性,然而对岩质滑坡而言,岩体的结构特征不仅控制着斜坡变形失稳模式,同样影响失稳后滑体碎屑化运动过程,甚至最终的危害范围。因此,文章使用离散元数值模拟方法,通过模拟不同结构面强度、结构面密度、结构面方向和岩块强度下岩质滑坡碎屑化运动过程,研究了不同源区岩体结构对岩质滑坡破碎特征、运动形式和运动距离的影响规律及影响机制。研究结果如下:（1）质心运动距离随结构面强度增大而增大,结构面抗拉强度提升10倍,质心运动距离增加3%;（2）结构面密度的增加使得块体破碎率随之增加,但运动距离和分布面积都呈下降趋势;（3）水平向结构面岩体的前缘运动距离和质心运动距离与其他方向结构面工况相比均降低10%左右,分布面积则缩减接近30%,破碎率最大;（4）随着岩块强度增加,破碎率降低,分布面积最终缩减40%,完整块体工况运动距离最终增大15%左右。结果有助于进一步理解岩质滑坡动力学过程,指导山区防灾减灾工作。 相似文献
5.
三峡库区泥质灰岩溶蚀作用与边坡岩体破坏 总被引：8，自引：0，他引：8
三峡库区泥质灰岩边坡的溶蚀与破坏问题,影响到三峡工程的顺利进行,正确掌握它的破坏规律,有利于边坡治理与防护工作。本文从岩体的基本地质信息入手,分析溶蚀作用从不同方面对边坡工程性质的影响。主要包括:岩体内部可溶岩成分被溶蚀后泥质成分富集,岩体成份发生变化;岩体密集节理裂隙发育,结构疏松,成为溶蚀液体的入渗通道,加剧深层岩体的溶蚀作用发生。溶蚀作用叠加不同的地质破坏因素后,三峡库区泥质灰岩岸坡的变形破坏类型总结为三类:薄-中厚层块裂式破坏、中-厚层点裂式破坏、厚-巨厚层层裂式破坏。 相似文献
6.
Haijian Su Hongwen Jing Honghui Zhao Liyuan Yu Yingchao Wang 《Environmental Earth Sciences》2017,76(4):179
Rock mass in the fault fracture zone has some characteristics such as low strength and poor self-stability, so the control mechanism of stability has been a difficulty in the research of underground engineering. A set of laboratory simulation method of fault fractured rock mass is developed to reflect the natural forming process of fault fracture zone. Compared with intact rock mass, the fault fractured rock mass has an obvious degradation in strength and deformation parameters, and the degradation index is between 22.79 and 84.06%. The bolt has a certain supporting effect on the fault fractured rock mass, and in the situation of end anchoring, the greater the pretightening force is, the better the enforcement effect will be. The stress field produced by high pretightening force can relieve the stress concentration around the bolt hole and make the initial cracks of rock mass away from the bolt plate. The evolution curve of bolt axial force in the process of uniaxial compression of large-scale specimen shows four stages, which are the initial compression stage, pre-peak joint load-bearing stage, post-peak joint load-bearing stage and the residual stage. Research results could provide some theory reference for the stability control of rock mass in the fault fracture zone. 相似文献
7.
Time-dependent behaviour of the rock mass 总被引：1，自引：0，他引：1
E. Z. Lajtai 《Geotechnical and Geological Engineering》1991,9(2):109-124
Summary The strength of intact rock and the rock mass is time-dependent. For intact rock experimental verification is available, for the rock mass the scale of time-dependence is a matter of judgement. Rock mass classifications do however emphasize the effect of time on tunnel stability. This paper examines the source of time-dependence in rocks and the rock mass and suggests a technique for estimating the long term strength. The long term strength of the rock mass is controlled by the time-dependent weakening of intact rock. Frictional resistance, a major source of rock mass strength, increases rather than decreases with time. Lifetime estimation for rocks can be accomplished phenomenologically or mechanistically. The first is a statistical process of wide applicability, the second is more restrictive in usage as its applies only to materials that suffer time-dependent strain (creep). Although the mechanistic route is more appealing, it has a major drawback as it concentrates on steady state creep. There is no strong evidence for steady state creep in rocks. The technique for long term prediction is developed through the analysis of the failure rate under constant load. The failure rate for a given load and environment is established from the frequency distribution of time-to-failure data as measured in static fatigue tests. As expected, the failure rate is strongly affected by both the loading and the environmental condition. The influence, however, is systematic and predictable. 相似文献
8.
裂隙岩体的渗透性是地质灾害、水电工程、矿山工程等研究中需要考虑的重要因素之一。岩体裂隙本身的渗透性取决于它的空间几何参数,因此,可以通过直接测量裂隙的几何要素计算出岩体的渗透系数。岩体的结构及其透水性直接关系到建筑物围岩的稳定及安全.通过水力劈裂试验,可以真实地反映高水压作用下岩体的结构和渗透性的变化规律.以某水电站工... 相似文献
9.
危岩体是一种典型的灾害地质体,其形成、变形与破坏受控于地质环境条件,地质基础要素在孕灾的过程中起着决定性作用,各基本地质要素与灾害形成的关系是研究危岩体变形规律和破坏机理的关键性问题。通过对三峡库区望霞危岩体区域地质构造作用分析,横石溪背斜构造解析,各类地质结构面发育特征统计和危岩体岩性组合方式及工程地质条件剖析,结合危岩体两次变形破坏过程,分析各因素对危岩体的形成及变形的关系。研究认为:孕育望霞危岩体的横石溪背斜雏形形成于印支期的隆升阶段,至燕山主期形成褶皱主体,后期则以继承性改造为主,危岩体的形成及孕育主要集中在背斜核部区域,枢纽位置尤为发育。控制危岩体变形的5条关键裂缝与顶部发育的"V"字形裂缝关系密切,其是在纵弯褶皱作用下背斜顶部脆性岩层受到强烈的拉裂影响,叠加台阶式层间滑动作用,形成与轴面近于平行的拉张裂缝。在望霞危岩体中发育多组地质结构面,其中原生结构面对各条关键裂缝及关键块体提供基础背景值,控制其规模、范围及变形强度。控制着变形关键部位特别是前缘软弱层变形位置、牵引区段及强烈程度。构造结构面主要控制关键裂缝的延伸方向、距离及样式,控制关键块体的变形方向,裂解范围及规模,掉块及崩裂位置,控制危岩体底部关键部位即压张裂缝的形成位置、张开度及位移方向。次生结构面主要控制后缘变形区,对各条关键裂缝控制其继承性变形,控制关键块体扩张,对岩体裂解破坏至关重要。同时,望霞危岩体在地层岩性上构成了典型的硬—软—硬岩性组合,为危岩体的变形提供了地质结构组合条件,其底部大面积的采空区控制着危岩体整体滑塌变形。 相似文献
10.
自三峡库区蓄水以来,岸坡消落带岩体劣化趋势明显,加速了岩质岸坡向欠稳定和不稳定发展,潜在崩塌涌浪灾害威胁长江航道安全。以三峡库区板壁岩为例,采用抗剪强度折减法分析在岩体劣化工况下危岩体的破坏过程与长期稳定性。结果表明：在自然工况下,板壁岩危岩体处于稳定状态;在库水+岩体劣化工况下,中部锁固段处拉应力集中,拉张裂缝逐步向顶部主控裂缝及底部基破碎带延展并相互贯通,可能发生滑移-剪切破坏;在库水+岩体劣化+强降雨极端工况下,约40个水文周期后,岩体强度下降30%,板壁岩危岩体的稳定性系数降至约1.14,处于欠稳定状态,建议进行工程防治,提高危岩体稳定性,以保障航道安全。研究结果可为三峡库区板壁岩及类似危岩体的防灾减灾工作提供科学合理的依据。 相似文献
11.
关于用岩体分类预测TBM掘进速率AR的讨论 总被引：1，自引：0，他引：1
以Maen、Pieve、Cogolo和Varzo 4条隧道为例,本文分析说明了岩体质量分类系统不能预测TBM净掘进速率PR的原因:由于影响岩体可掘进性的因素与影响岩体质量的因素不一样,且岩体质量分类系统多采用半定性半定量的评分形式描述岩体条件,故岩体的质量分数值与TBM的净掘进速率PR很难有一一对应的关系。因此,岩体质量分类系统和基于此的预测模型不能够用来预测TBM的净掘进速率PR。根据TBM施工隧道岩体分类的目的及TBM施工的特点,提出预测TBM净掘进速率PR的岩体分类系统应与评价岩体稳定的岩体分类系统分开进行。用岩体可掘进性分类系统预测净掘进速率PR,用岩体质量分类系统预测TBM利用率U,从而计算出TBM的掘进速率AR。 相似文献
12.
节理岩体是工程中最常见的一类岩体,其在地震、爆炸等动载下的力学响应及破坏过程对相关工程安全性的影响至关重要。采用基于有限元应力分析和统计损伤理论开发的动态版RFPA2D数值模拟软件,对动载下节理岩体的动态破坏过程进行了模拟,重点讨论了节理条数、节理贯通度、节理倾角及应力波峰值对岩体动态破坏过程的影响规律。计算结果表明,断续节理岩体动态破坏过程及破坏强度与节理构造形态、应力波峰值密切相关。相同动载下,随着节理条数的增加,岩体破坏程度以及应力波能量损失增强,但当节理条数数超过一定值后,岩体破坏程度及应力波能量损失逐渐趋于稳定;节理贯通度较小时,岩体破坏程度较低且破坏单元自上而下均匀分布。随着节理贯通度的增加,岩体破坏增强,且破坏主要出现于节理上部岩体;节理倾角较小时,节理上部岩体破坏严重,易形成次生贯通裂纹。随着节理倾角增加,破坏范围逐渐变大,不易形成次生贯通裂纹;倾角为45°～60°时,岩体破坏效果最佳;动载荷的峰值越大,试样的破坏越严重。当峰值达到一定值时,节理附近发育出多条裂隙并向上下方不断发展而导致岩体完全破坏。在不同节理贯通度工况下与岩石霍布金森压杆（SHPB）试验结果进行比较,结论吻合,证明该数值模拟的合可行性和结论的可靠性。 相似文献
13.
E. Widzyk-Capehart P. Lilly 《Fragblast: International Journal for Blasting and Fragmentation》2002,6(2):151-168
Blasting is the primary comminution process in most mining operations. This process involves the highly complex and dynamic interaction between two main components. The first is the detonating explosive and the second is the rock mass into which the explosive is loaded. The mechanical properties of the rock material (such as dynamic strength, tensile strength, dynamic modulus and fracture toughness) are important considerations in understanding the blasting process. However, it is the characteristics of the geological defects (joints, foliation planes, bedding planes) within the rock mass that ultimately determine how effectively a blast performs in terms of fragmentation, all else being equal. The defect characteristics include, but are not limited to, their orientation, spacing, and mechanical properties. During the blasting process, some of the geotechnical characteristics of the rock mass are substantially changed. From the blasting outcome point of view, the most notable and important is the change in fragment size distribution that the rock mass undergoes. The pre-blast in situ defect-bounded block size distribution is transformed into the post-blast muckpile fragment size distribution. Consequently, it is fundamental to our understanding of and ability to predict the blasting process that both the blastability of a rock mass and its transformation into the fragment size distribution can be appropriately quantified. 相似文献
14.
甘肃省关山隧道是一条受高地应力影响的大埋深硬脆性闪长岩铁路隧道,位于青藏高原东北缘,构造活跃,运动速率较大,且方向变化显著的六盘山挤压隆升构造区。在隧道开挖过程中围岩变形破坏现象明显,围岩等级低于前期岩体质量分级,表现出强烈的岩体质量劣化和各向异性。针对该问题,除了采用矿物成分和微结构分析寻找原因,还通过现场结构面统计分析对围岩质量劣化和各向异性进行描述,同时运用自行研发的钻孔电视进一步分析开挖前后一定时间间隔内围岩的渐进式变形和破坏。钻孔电视试验结果表明,尽管闪长岩作为一种硬脆性岩体,单轴抗压强度（UCS）高于现场地应力值,但其变形和破坏却普遍发生,开挖过程中新生裂隙迅速发育,原先在高地应力下闭合的裂隙也会重新张开和发展,围岩劣化,稳定性降低。为了进一步分析围岩的变形破坏过程,设计了变压力大小和方向的单轴抗压试验,试验中闪长岩的单轴压力值低于单轴抗压强度,试验结果与钻孔电视试验观测结果吻合,证明了在开挖引起的地应力剧烈变化条件下硬脆性闪长岩结构劣化,存在变形破坏的可能性。在大埋深高地应力条件下,除了岩体的各向异性,地应力的变化也是硬脆性围岩稳定性的重要考量因素。 相似文献
15.
Rock mass failure is a particularly complex process that involves the opening and sliding of existing discontinuities and the fracturing of the intact rock. This paper adopts an advanced discretisation approach to simulate rock failure problems within the discontinuous deformation analysis (DDA) framework. The accuracy of this approach in continuum analysis is verified first. Then, the advanced discretisation approach for fracturing modelling is presented, and the discretisation strategy is discussed. Sample rock static failures are simulated and the results are compared with experimental results. Thereafter, with a generalised definition of the artificial joints, this approach is further extended and applied in the simulation of blast-induced rock mass failures in which the instant explosion gas pressure obtained by the detonation pressure equation of state is loaded on the main blast chamber walls and the induced surrounding connected fracture surfaces. In the simulation instance of rock mass cast blasting, the whole process, including the blast chamber expansion, explosion gas penetration, rock mass failure and cast, and the formation of the final blasting pile, is wholly reproduced. 相似文献
16.
Omid Saeidi Seyed Rahman Torabi Mohammad Ataei 《Geotechnical and Geological Engineering》2013,31(5):1477-1495
Knowledge of drillability of rock masses in engineering projects is very important in determining drilling costs. In drilling operations, so many parameters such as the properties of rock and the drilling equipment affect the drilling performance. In this study, after discussing the rock mass drillability process and identifying all the effective parameters, interaction matrixes based on the rock engineering systems, that analyze the interrelationship between the parameters affecting rock engineering activities, is introduced to study the rock mass drillability tribosystem. Given that interaction matrix codes are not unique numbers, and then possible interactive intensities are calculated for each matrix and a group decision-making method, Fuzzy–Delphi–AHP technique has been used to obtain appropriate weights. As a result, rock mass drillability index (RMDI) is presented to classify the rock mass drillability. The results indicate the ability of this method to analyze rock mass drillability procedure. Drilling data along with laboratory rock properties from Sungun copper mine were collected and were ranked according to the new classification system. Fifteen zones at the mine site were ranked based upon the new index RMDI and a reasonable correlation was obtained between measured drilling rate at the zones and RMDI data. 相似文献
17.
卸荷过程岩体中弹性波波速变化分析 总被引：1，自引：0，他引：1
伴随岩体卸荷过程,岩体内部应力状态要进行调整,同时岩体内部几何结构也要发生变化。由于卸荷过程应力状态变化很复杂,文中利用卸载过程中岩体内部几何结构的变化来反映卸载过程,通过岩体几何结构对弹性波传播的影响来分析卸载过程的波速。为考虑弹性波作用下局部裂纹的相互作用,采用双裂纹模型近似分析。在双裂纹体系内部采用“相互作用”分析法,以部分考虑波在岩体内的多次散射;在双裂纹体系之间采用线性叠加分析法,以考虑岩体中缺陷影响的局部化。通过节理裂隙的张开程度和节理裂隙的张开率描述卸载过程对双裂纹体系的影响,由此,对比分析了开挖卸载过程中四种不同的玄武岩与主频25 kHz和主频1 kHz对应的弹性波波速的变化。结果表明,随着卸载过程的推移,主频25 kHz声波和主频1 kHz地震波对应的相对波速逐渐减小,但声波波速的减小幅度要比地震波减小的幅度小,声波波速可以降低到原来的80%,而地震波波速可以降低到原来的50%。结论对于水利工程、隧道工程等建基面的验收和评价有很好的指导意义 相似文献
18.
地下工程岩体渗流-损伤-应力耦合问题的研究对于巷道围岩的稳定性分析具有重要意义。本文在总结分析了巷道变形破坏类型影响因素的基础上,基于弹塑性力学、渗流力学以及损伤理论建立了岩体渗流-损伤-应力耦合模型。该模型充分考虑了多物理场耦合过程中,工程岩体的非均质性,岩体力学参数发生的动态弱化过程,围岩塑性屈服的峰后特性以及渗透系数在损伤过程中的突变性。基于多物理场耦合软件,数值模拟结果分析得到,使用该模型能更好地反映巷道围岩的屈服破坏程度和渐进破坏过程。应用该模型分析不同深度下的巷道围岩渐进性破坏过程可以得出:水平地应力为主导的地层中的巷道,屈服破坏主要发生在顶拱和底板,竖直地应力为主导的地层中的巷道,屈服破坏主要发生在两侧边墙,水平地应力和竖直地应力相近的地层中,巷道四周均发生不同程度的破坏,这与工程实际有很好的符合。 相似文献
19.
裂隙充填蒙脱石对巷道稳定性的影响 总被引：1，自引：2，他引：1
在深入调查大冶铁矿尖林山矿体上盘闪长岩蒙脱石化蚀变带地压显现特点的基础上，探索了该岩体失稳的原因，提出了提高巷道蒙脱石化围岩稳定性的措施。 相似文献
20.
崩落法开采的金属矿山往往会伴随着一系列的地质灾害现象。为保证矿区安全生产,开展崩落法开采引起的岩层移动的时效性研究具有重要意义。以程潮铁矿西区下盘为研究对象,通过将地表10多年GPS监测数据的整理分析,并与现场破坏调查结果和工程地质条件相结合,进而探究不同分区下岩层移动的时效行为。研究结果表明：岩层移动的时效行为与其破坏过程有着密切的关系,不同分区下的岩层移动的时效行为是不同的,可分为初始变形、渐进变形、加速变形和残余变形共4个阶段,分别对应着稳定状态、临界状态、失稳状态以及采矿结束后的蠕变状态;初始变形阶段对应着岩体的初始蠕变过程,渐进变形阶段反映了岩体抵抗自身变形的过程,加速变形阶段与深部破坏面的形成和强烈的应力释放有关;崩落碎石在采矿作业停止后失去了流动空间,在岩体变形挤压下会对围岩提供支撑力进而限制了岩层移动的进一步发展;残余变形时间由岩体的蠕变特性和崩落碎石的压密过程所控制,倾倒滑移区因需要经历一个额外的碎石压密过程而导致残余变形时间更长。 相似文献