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1.
冻融作用下岩石力-热-水耦合本构模型研究 总被引：1，自引：0，他引：1
在寒区隧道工程中,冻胀的水分迁移作用加剧了隧道围岩的冻融破坏。耦合水分迁移作用的岩石本构模型对防治冻融渗漏、崩塌等隧道围岩灾害有着重要意义。基于内状态变量理论,将冻胀过程中的水分迁移量作为本征变量引入Helmholtz自由能,在热力学框架下建立了一个岩石力-热-水耦合本构模型。模型描述了温度和水分迁移对冻融后岩石损伤阈值、等向强化饱和值、等向强化速率等力学参数的影响。模拟了岩石冻融后力学性质的劣化。区别于全量经验公式,本模型以增量形式给出,为复杂应力历史条件下的数值模拟提供了便利。通过将模型模拟曲线与冻融后岩石常规三轴压缩试验曲线进行对比,初步验证模型的可靠性,为实际寒区工程的冻胀破坏预测提供参考。 相似文献
2.
开挖损伤区不仅对一般工程的稳定性具有重要影响,同时其渗透特性变化也是一些特殊工程(如高放废物地质处置工程)关心的重点。该文结合桓集隧道四标段工程,通过在隧道洞壁取样而后进行室内超声波波速和渗透试验测试的方法,研究了TBM开挖隧道围岩的损伤区范围和渗透特性变化,同时也对样品洞壁端面的粗糙程度进行了量测,结果表明:(1)该隧道围岩强度较高,且工程区地应力属于低—中等水平,围岩损伤主要由TBM开挖造成。(2)隧道围岩的原岩波速在4713~5376 m/s之间,损伤区波速在2943~4856 m/s之间,围岩质量较好处的原岩波速和损伤区波速均大于围岩质量较差处的对应值,而围岩质量较差处的最大波速降比比围岩质量较好处的数值略大;各样品的损伤区范围在11.0~52.0 mm之间,一般围岩质量越好,损伤范围越小。(3)围岩质量较好处的原岩和损伤样品渗透率均小于围岩质量较差处的对应样品值;同一岩芯的损伤样品渗透率大于原岩样品,本次研究的机械开挖损伤使围岩的渗透率提高1.94~3.75倍。(4)研究的隧道表面波谷和峰高范围在-5~4 mm之间,满足SKB对处置孔壁粗糙程度的要求。 相似文献
3.
对不同初始饱和度红砂岩冻融循环前后进行物理及力学试验研究,探讨初始饱和度对红砂岩冻融损伤的影响。本文设定红砂岩试样初始饱和度为20%、40%、60%、80%、100%,冻融次数设定为20次,对冻融前后试样分别测定质量、纵波波速以及进行单轴压缩试验。试验结果表明：1）冻融后不同初始饱和度红砂岩的物理性质发生变化,纵波波速降低、质量减小,但变化程度不同;2）随饱和度的增大,试样经冻融后峰值强度和弹性模量均呈降低趋势,但只有饱和度大于60%时,降低趋势较明显。本文研究为寒区隧道及地下工程建设以及岩土地质灾害监测与治理提供理论依据和试验基础。 相似文献
4.
寒区隧道冻胀力随时间和隧道进深呈三维时空分布,为建立描述冻胀力时空效应的简化模型,首先以某寒区隧道温度场测试成果为基础,建立了三维温度场模型,通过Stephen公式得到围岩冻结深度变化规律,以围岩冻结深度为参数,结合冻融圈整体冻胀模型和风化层冻胀模型建立了新的冻胀模型。分析结果表明：围岩冻结深度受温度场影响呈三维时空分布,随隧道进深逐渐减小,随时间呈弦函数变化;考虑风化层和破碎层建立冻胀模型,当冻结深度小于风化层厚度时,冻胀力只由风化层产生,冻结深度大于风化层厚度时,冻胀力由风化层和扰动层叠加产生;冻胀力时空分布规律与围岩冻结深度变化规律一致。 相似文献
5.
高寒隧道保温结构的优化设计研究
——以西藏圭嘎拉隧道为例 总被引：1，自引：1，他引：0
为了提高季节冻土隧道的防冻保温性能,常采用铺设聚氨酯类有机保温层的方式以防止围岩冻结,但由于有机材料在冻融循环过程中老化速度快、保温结构设计缺少科学依据等局限性,使得部分隧道在长期运营过程中反复出现冻融病害。以西藏圭嘎拉隧道为研究对象,通过建立热流固耦合计算模型,对现行保温措施的防冻效果进行分析,发现距离洞口一定长度范围内的围岩仍会发生冻融破坏。在隧道运营后第20年2月15日,距洞口5 m处断面拱顶围岩的边界温度仅为-0.91 ℃,并且该关键位置的纵向冻结长度超过500 m,严重影响隧道结构的安全。为防止此隧道出现冻害问题,提高其服役能力,拟采用新型无机建筑材料气凝胶毡对隧道的保温结构进行加固,其具有良好的保温、阻燃和耐久性能,并且铺装简便、易于操作。此外通过对不同厚度气凝胶毡条件下的围岩温度场进行多维度分析,确定了最不利时刻气凝胶毡厚度与拱顶围岩关键位置纵向冻结长度之间的关系。研究成果可为圭嘎拉隧道防冻保温优化设计提供技术支持,不仅能保障隧道结构的安全性和稳定性,也能为季节冻土隧道保温结构的设计、施工及维护提供参考依据。 相似文献
6.
为探讨冻融对寒区工程岩石剪切蠕变特性的影响,以吉林省辉白隧道花岗岩为研究对象,对经历不同冻融循环次数的试样开展细观特征分析和剪切蠕变试验。试验结果表明：（1）随着冻融次数的增加,试样裂隙、孔隙不断扩展,岩石表面损伤现象愈发明显;（2）试样主要以中小孔隙为主,孔隙度随着冻融次数的增加呈非线性增长趋势;（3）随着冻融循环次数增加,蠕变变形量和蠕变速率逐渐增大,而蠕变时长、破坏应力和长期强度均呈现明显降低趋势。根据试验结果,进行冻融岩石非定常蠕变参数的表达,提出了冻融岩石损伤黏性元件,构建了花岗岩冻融剪切蠕变本构模型。将蠕变试验曲线和理论模型拟合曲线进行对比,验证了模型的正确性和适用性。通过对蠕变参数进行敏感性分析,研究了其对花岗岩蠕变变形的影响,并给出了蠕变参数随冻融循环次数的变化规律。该研究结果对于寒区岩体工程长期稳定性评价具有指导意义。 相似文献
7.
《岩土力学》2021,(2)
为探讨冻融对寒区工程岩石剪切蠕变特性的影响,以吉林省辉白隧道花岗岩为研究对象,对经历不同冻融循环次数的试样开展细观特征分析和剪切蠕变试验。试验结果表明:(1)随着冻融次数的增加,试样裂隙、孔隙不断扩展,岩石表面损伤现象愈发明显;(2)试样主要以中小孔隙为主,孔隙度随着冻融次数的增加呈非线性增长趋势;(3)随着冻融循环次数增加,蠕变变形量和蠕变速率逐渐增大,而蠕变时长、破坏应力和长期强度均呈现明显降低趋势。根据试验结果,进行冻融岩石非定常蠕变参数的表达,提出了冻融岩石损伤黏性元件,构建了花岗岩冻融剪切蠕变本构模型。将蠕变试验曲线和理论模型拟合曲线进行对比,验证了模型的正确性和适用性。通过对蠕变参数进行敏感性分析,研究其对花岗岩蠕变变形的影响,并给出了蠕变参数随冻融循环次数的变化规律。研究结果对于寒区岩体工程长期稳定性评价具有指导意义。 相似文献
8.
【内容简介】北方寒冷地区的混凝土的破坏多数与冻融作用有关,混凝土结构在冻融循环作用下的破坏,关系到建筑物使用寿命、工程质量、运营安全等方面的问题。本书基于混凝土冻融破坏机理研究分析,介绍了改善抗冻性能各种途径,对混凝土设计和施工中的防冻措施提出具体要求。全书包括六部分:混凝土冻融破坏机理、混凝土抗冻试验、混凝土防冻外加剂、掺合料改善混凝土防冻性能、抗冻混凝土设计、混凝土防冻施工。本书有助于混凝土冻融破坏理论研究工作,对在实际工程 相似文献
9.
多年冻土区水泥稳定砂砾基层抗冻性能研究 总被引：2，自引：1，他引：1
多年冻土地区路面使用过程中的许多病害与基层状况直接相关.水泥稳定砂砾作为我国传统的半刚性基层材料,在多年冻土地区公路路面结构中得到了普遍运用.为研究水泥稳定砂砾不同水泥掺量、不同养生龄期下的抗冻性能,通过提出合理的抗冻试验方法分别进行了水泥稳定砂砾冻融温度、冻融时间、冻融次数、试件的养生龄期及抗冻指标方面的试验研究. 结果表明：水泥剂量越高,水泥稳定砂砾冻前、冻后的抗压强度值越高,说明其抗冻性能越好;水泥稳定砂砾从28 d开始抗压强度、冻融后抗压强度及冻融后劈裂强度都明显增加,证明水泥稳定砂砾从28 d开始已具有一定的抗冻性. 提出的抗冻试验方法和指标要求适合多年冻土地区半刚性基层材料,有一定的实用价值. 相似文献
10.
昆明白泥井3号隧道围岩稳定性FLAC3D模拟 总被引：4，自引：2，他引：4
应用FLAC^3D数值模拟软件对昆明白泥井3号隧道围岩稳定性进行了分析和评价。结果表明隧道支护后围岩的最大变形出现在隧道右侧拱顶，为1．00cm；隧道支护后左侧拱和右侧拱脚处剪应变明显增大，为应力集中区；围岩可以通过自身应力、应变和能量的调整，使整个隧道围岩处于稳定状态；同时也表明FLAC^3D用于隧道围岩变形分析是可行的。 相似文献
11.
东濮凹陷北部沙三中亚段广泛发育盐岩和烃源岩,这两个看似不能共存的物质却在这里互层共生。该时期研究区沉积特征为多盐韵律与多层烃源岩互层共生、连续沉积,单个盐韵律厚度从几米到十几米,烃源岩有机质丰度高、类型好。平面上,两者在湖盆沉积沉降中心共生;垂向上,高有机质丰度、好干酪根类型与高盐度地层具有较好的对应关系。因而成为恢复古气候和古环境的重要研究对象。通过岩石学、古生物学以及Sr/Ba、B/Ga、(V+Ni+Mn)、Fe/Mn、Sr/Cu、Mg/Ca、V/(V+Ni)、稀土元素含量和氯同位素等方法对凹陷北部沙三中亚段的沉积环境进行研究。结果表明,凹陷北部沙三中亚段为深水沉积的还原环境,古盐度较高,达到半咸水-咸水沉积;微量元素和孢粉化石特征表明研究区沙三中亚段为温暖潮湿的环境。 相似文献
12.
The Importance of the Precipitation and the Susceptibility of the Slopes for the Triggering of Landslides Along the Roads 总被引：3，自引：1，他引：2
Clemente Irigaray Francisco Lamas Rachid El Hamdouni Tomás Fernández José Chacón 《Natural Hazards》2000,21(1):65-81
In order to characterise the influence of the heavyrains on the observed landslides during the 1996–1997hydrological cycle, rainfall records for the last 100years are analysed from 104 stations in easternAndalusia. Regarding the amounts of rain recordedbetween October 1996 and March 1997 in the 104stations studied, 31 presented new all-time records;15 presented values that were 80–100% of thepre-1995 record; 49 stations, 80–50%; and 9stations, < 50%. A map has been devised of thesusceptibility of the materials through which thesouth-eastern Andalusian road network crosses,together with an inventory of the damage caused byinstability phenomena on banks and cuttings of theroad network during the winter of 1996–1997. Therelationships between the rainfall during the studyperiod, the damage caused to the road network and thesusceptibility of the materials affected are analysed.The results indicate that there is a clearcorrespondence between the rainfall recorded and thesusceptibility of the materials with the inventorieddamage. It is concluded that the widespread seriousdamage caused in early 1997 to the roads andsurrounding areas in the Alpujarra region and thecoast of the Province of Granada was mainly caused bythe extraordinarily heavy rains. However, considerablyless damage was observed where the susceptibility ofthe terrain is low, thus highlighting the extremeusefulness of terrain-susceptibility maps for riskprevention and territorial planning. 相似文献
13.
郯庐断裂南段研究进展与断裂性质讨论 总被引：13，自引：3，他引：13
据1：5万区域地质调查和专题研究资料，就郯庐断裂带是否南延与消失的原因，其与大别—苏鲁造山带交截形成的假位错效应，以及与中新生代沉积盆地形成演化的关系等作了新的阐述。在此基础上，讨论了郯庐断裂带是否为巨大的左行平移断层或转换断层。认为郯庐断裂带可能是在“古郯庐带”的基础上于早侏罗世重新活动、白垩纪强烈活动的地堑型枢纽断裂带。 相似文献
14.
15.
Guboglo M. N. 《GeoJournal》1980,4(1):53-58
International unity is becoming ever stronger in this country owing to an increasing similarity in the development of the cultural environment. This comprises the provision of all the country's republics with a sufficient number of schools, theatres, and other institutions and cultural information media in accordance with the needs of the population. An important part is played by the rise in ‘the general educational level, as well as the level of professional qualifications and skills. Among all the Soviet nations and nationalities, this rise being more rapid among formerly backward peoples. Prominent among the factors of internationalization is the progressive development of the nationalities’ cultural resources, while professional culture is being increasingly brought within the reach of the masses.The implementation of the nationalities policy promotes the all-round development of all Soviet nations and nationalities, their drawing together, the upsurge of the individual capabilities of every Soviet citizen. 相似文献
16.
Dean S. Oliver 《Mathematical Geology》1998,30(7):911-933
In reservoir characterization, the covariance is often used to describe the spatial correlation and variation in rock properties or the uncertainty in rock properties. The inverse of the covariance, on the other hand, is seldom discussed in geostatistics. In this paper, I show that the inverse is required for simulation and estimation of Gaussian random fields, and that it can be identified with the differential operator in regularized inverse theory. Unfortunately, because the covariance matrix for parameters in reservoir models can be extremely large, calculation of the inverse can be a problem. In this paper, I discuss four methods of calculating the inverse of the covariance, two of which are analytical, and two of which are purely numerical. By taking advantage of the assumed stationarity of the covariance, none of the methods require inversion of the full covariance matrix. 相似文献
17.
某高速公路下伏煤矿采空区稳定性分析 总被引：10，自引：0，他引：10
在论述某高速公路下伏砦脖煤矿采空区地质、采矿和工程地质特征的基础上, 进行了稳定性数值模拟分析, 定性与定量地分析与评价了该煤矿采空区的地表变形特征及稳定性。研究结果表明: 该煤矿采空区的变形尚未完成, 对拟建的高速公路将产生很大的危害, 必须采取相应的工程治理措施。 相似文献
18.
Jiayu Rong Michael Melchin S. Henry Williams Tatyana N. Koren Jacques Verniers 《《幕》》2008,31(3):315-318
The Global Stratotype Section and Point （GSSP） for the base of the Silurian System was defined in 1985. Since that time, a number of researchers have suggested that this section has serious deficiencies for use as a GSSP. As a result, in 2000, the Subcommission on Silurian Stratigraphy （SSS） proposed undertaking a formal restu@ of this GSSP, which was subsequently approved by the International Commission of Stratigraphy （ICS）. The result of this restudy was the formal proposal that the current GSSP, at 1.6 m above the base of the Birkhill Shale, at Dob＇s Linn, Scotland, should be maintained as the same locality and stratigraphic level, but the bios- tratigraphical definition of the boundary should be revised. The previously defined, basal Silurian grapto- lite zone, the Parakidograptus acuminatus Zone, should be subdivided into a lower Akidograptus ascensus Zone and a higher E acuminatus Zone. The base of the A. ascensus Zone, marked by the first appearance of A. ascensus, should be regarded as the biostratigraphic mark for the base of the Silurian. This proposal has now been formally approved by the SSS and ICS, and ratified by International Union of Geological Sciences. This is the first GSSP to undergo formal restudy and redefini- tion, and the proposal also included a recommended procedure for restudy of GSSPs. 相似文献
19.
Deviation of the major axis of the inertia ellipsoid of the Moon from the direction toward the Earth
B. P. Kondratyev 《Astronomy Reports》2017,61(8):709-714
It is known from observations that the center of mass of the Moon does not coincide with the geometric center of its figure, and the line connecting these two centers is not aligned with the direction toward the center of the Earth, instead deviating toward the Southeast. This stationary deviation of the axis of the inertia ellipsoid of the Moon to the South of the direction toward the Earth is analyzed. A system of five linear differential equations describing the physical libration of the Moon in latitude is considered, and these equations are derived using a new vector method taking into account perturbations from the Earth and partly from the Sun. The characteristic equation of this system is obtained, and all five oscillation frequencies are found. Special attention is paid to the fifth (zero) frequency, for which the solution of the latitude libration equations are stationary and represents a previously unknown additional motion of the rotational axis of theMoon in a cone with a small opening angle. In contrast to the astronomical precession of the Earth, the rotation of the angular-velocity vector is in the positive direction (counter-clockwise), with the period T 3 = 27.32 days. On this basis, this phenomenon has been named “quasi-precession.” This quasi-precession leads to a stationary inclination of the major axis of the inertia ellipsoid of theMoon to the South (for an observer on Earth), making it possible to explain one component of the observed deviation of the center of mass of the Moon from the direction toward the Earth. The opening angle of the quasiprecession cone is approximately 0.834″. 相似文献
20.
Important tendencies in development of the world mineral-resources sector at the beginning of the 21st century were an increase in production and consumption of mineral materials differentiated by types of metals and nonmetallic mineral raw materials, by countries and regions, as well as the concentration of the production of mineral raw materials in a small number of countries, and a reduction in industrial reserves of minerals in the world economy, even at the current stage of their extraction. These tendencies should be taken into account in working out a strategy for development of the Russian mineral raw-material base. 相似文献