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1.
《岩土力学》2017,(4):965-972
土石混填体是一种由土体和块石混合形成的非均质散体材料,其抗剪强度特性主要受含水率、含石量、颗粒级配及压实度等因素的影响。基于室内大型直剪试验,在前人研究的基础上,考虑级配参数的影响,通过控制试样质量与体积达到试验所需的压实度水平,分析了各主要参数对土石混填体抗剪强度的影响规律。试验结果表明:在级配良好的情况下,随不均匀系数的增大,土石混填体抗剪强度先增加后减小,不均匀系数在22.99左右时取得峰值,而曲率系数对其影响较小;土石混填体的抗剪强度分别随着含石量、压实度的增加而不断增加,但当压实度超过92.5%后增加趋势变缓。随着含水率的增长,其抗剪强度先增加后减少,在最优含水率附近时达到峰值。基于Matlab多元线性回归分析,得出了各因素对土石混填体抗剪强度影响程度的主次顺序为:含石量含水率压实度不均匀系数曲率系数,通过非线性回归分析得到了其抗剪强度关于各因素的拟合公式,且相关指数R~2大于0.9。 相似文献
2.
全晓娟龚禹为汪波钟官峰周尚武 《冰川冻土》2023,(3):1016-1025
冻融作用会对土体结构和性质造成影响,在冻融作用下,不同类型土壤的抗剪强度变化呈现出不同规律。本文选取青藏高原具有代表性的黏土,开展不同初始含水率和不同冻融循环次数下的重塑土抗剪强度变化研究,结合压电陶瓷监测试验,探究冻融循环下青藏黏土抗剪强度指标的变化模式和规律。结果表明:在反复冻融作用下,青藏黏土抗剪强度、黏聚力和内摩擦角随含水率增大呈阶梯下降;同一含水率的抗剪强度和黏聚力劣化曲线可以分为快速劣化和稳定两个阶段,内摩擦角呈先减小后增大的变化趋势;冻融循环过程中第1次循环对青藏黏土抗剪强度影响最为明显;采用压电陶瓷监测的应力波信号通过小波包分析可以得到真实信号振幅和应力波能量,二者均能反映青藏黏土抗剪强度的劣化趋势。本文提出的强度劣化指标能很好地反映青藏黏土抗剪强度的劣化程度,这在未来工程实际中有着一定的应用前景。 相似文献
3.
对于存在滑带土应变软化效应的堆积层滑坡,在根据弹塑性有限元法获得坡体应力场的基础上,由滑带上任一点剪应力与抗剪强度大小关系,考虑滑带土的峰值强度、过渡强度和残余强度,提出了包括推移式滑坡与牵引式滑坡的滑带抗剪强度分区方法;进而结合传递系数法,给出了考虑滑带土不同区段抗剪强度参数取不同值的斜坡稳定性分析方法;讨论了基于理想弹塑性、考虑应变软化和弹性本构模型获得坡体应力场的有限元方法对稳定系数的影响。实例分析表明,这3种方法计算的斜坡稳定系数差异较小;考虑滑带分区得到的斜坡稳定系数比不考虑分区的峰值稳定系数约小14.1%～21.6%。 相似文献
4.
门楼水库溢流坝段岩石与混凝土抗剪参数的确定 总被引：3，自引：1，他引：2
通过对门楼水库溢流坝段不同位置、不同深度、不同岩石风化程度在不同混凝土强度和不同含水率情况下近百块试块的室内直剪试验,研究了岩石和混凝土胶结面的抗剪强度与混凝土强度、岩石的风化破碎程度和含水率的关系。结果表明,混凝土的强度对胶结面的抗剪强度具有明显的影响;对于块状及次块状结构类型岩体,胶结面抗剪强度参数基本相同,但裂隙块体强度降低很多,部分块体破坏形态已不在是沿胶结面破坏,而是部分迁就胶合面,部分追随岩体内的结构面,并形成较大的起伏;随着含水率的增加,凝聚力和内摩擦角都明显降低。试块的抗剪强度只代表试验点的强度,为了得到建基面的抗剪强度,将岩石和混凝土的抗剪强度看作随机变量,引入区域化内变量和变异函数反映抗剪强度的随机性和结构性,通过克里格方程求得各个样本的权值,进而求出不同建基面的抗剪参数。 相似文献
5.
结合基桩承载过程中的桩周土体应力状态分析和桩土界面摩擦特性分析,推导出基于土体应力状态的沿桩土界面的土体抗剪强度计算模型和基于界面摩擦特性的界面抗剪强度计算模型。通过对比土体抗剪强度和界面抗剪强度,推导出受该两种强度耦合作用影响的极限侧阻力计算模型,并用上海某工程算例验证该模型的合理性和可行性,同时利用该模型分析不同类型的土的极限侧阻力随埋深的分布规律。结果显示：因内摩擦角和侧压力系数之间的不同关系,极限侧阻力随埋深表现出不同的分布特点,在特定关系下,存在一个临界深度,超过该深度极限侧阻力维持在一个稳定值甚至不断减小直至为零。 相似文献
6.
考虑碱浓度、养护时间、干密度、含水率等影响因素,通过室内直剪试验,研究碱污染红土的抗剪强度特性,分析碱与红土的相互作用过程。结果表明:碱污染引起红土抗剪强度减小,碱浓度从4%到16%,抗剪强度减小程度逐渐增大;试样的养护总体上降低了碱污染红土的抗剪强度,随养护时间延长,抗剪强度呈先减后增再减的变化趋势;16%碱浓度时抗剪强度降低程度为35.0%,养护10d时抗剪强度降低程度为16.8%,碱浓度的影响大于试样养护时间的影响。碱污染红土的抗剪强度随干密度的增大而增大,随含水率的增大而减小,含水率的影响大于干密度的影响。碱污染引起红土的抗剪强度发生变化,其碱土作用特征可以从水解作用、侵蚀作用、胶结作用、溶解作用几个方面进行解释。 相似文献
7.
不同剪切速率对风化砂改良膨胀土抗剪强度指标的影响 总被引：1，自引：0，他引：1
土的抗剪强度指标受含水率、剪切速率以及土样的类别等多个因素的影响。为了研究不同剪切速率对风化砂改良膨胀土的抗剪强度指标的影响规律,分别在2.4,0.8 mm/min剪切速率下对不同含水率和不同掺砂比例的风化砂改良膨胀土样进行了室内直剪试验,得到了不同剪切速率下改良膨胀土的抗剪强度指标值。试验表明:采用2.4 mm/min的剪切速率测得的抗剪强度指标比采用0.8 mm/min的剪切速率测得的值要大;通过对比试验数据可知,剪切速率对内摩擦角的影响比对黏聚力的影响相对来说较小,对砂土的抗剪强度指标的影响比对黏土的抗剪强度指标要小,对含水率较小的土样的抗剪强度指标的影响比对含水率大的土样的抗剪强度指标要大。对于风化砂改良膨胀土的抗剪强度指标的测定时的剪切速率应采用规范要求的0.8 mm/min。 相似文献
8.
结构面抗剪强度参数对岩质边坡稳定的影响 总被引：4，自引：2，他引：2
边坡工程中,结构面抗剪强度是非常重要的力学参数,合理地选择确定抗剪强度的方法,常常要分析c、值在边坡稳定中的作用。根据极限平衡原理,对10~30m高的平面滑动型边坡不同抗剪强度的控稳结构面c、值在边坡稳定中的作用进行了定量分析。研究表明c值对稳定系数的影响随坡高增大逐渐减弱,值对稳定系数的影响随坡高增大逐渐增强。得到了不同坡高下c、值边坡稳定作用等值曲线,该曲线很容易确定抗剪强度参数c、值在边坡稳定中的作用。 相似文献
9.
安哥拉Quelo砂抗剪强度特性试验研究 总被引：1，自引：0，他引：1
基于安哥拉Quelo（Muceque）砂原状土和重塑土的直剪试验,探讨了结构性、含水率、干密度对Quelo砂抗剪强度的影响。试验结果表明,结构性对Quelo砂的抗剪强度影响较为复杂,原状土与重塑土的抗剪力学指标具有明显差异;Quelo砂遇水软化特性显著,原状土和重塑土的黏聚力和内摩擦角随含水率的增大近似呈对数衰减;Quelo砂级配良好,压实后抗剪强度高,适宜用作回填材料,重塑土的黏聚力随干密度的增大近似呈线性增大,内摩擦角随干密度的增大分为稳定段和增大段,呈分段函数的特征。 相似文献
10.
研究含水率和加筋率对稻秸秆加筋土的强度影响问题,对促进稻秸秆加筋土在边坡生态防护中的推广应用具有重要作用。针对边坡生态防护所采用的稻秸秆加筋土,通过直剪试验研究不同加筋率与含水率条件下加筋土抗剪强度的变化规律。试验通过加水法和烘干法改变6种加筋率（加筋率为:0~0.5%）试样的含水率,然后进行室内直剪试验。结果表明:（1）不同加筋率条件下加水法所得加筋土试样的抗剪强度、粘聚力与内摩擦角均随含水率的增加先增大后减小,并在土体最优含水率14.8%时出现峰值,而烘干法所得加筋土试样的抗剪强度、粘聚力与内摩擦角则随含水率的增加而逐渐减小;（2）加水法与烘干法所得抗剪强度、粘聚力与内摩擦角受含水率的影响均存在临界值,约为19%;（3）在增长率相同的条件下含水率对加筋土抗剪性能的影响大于加筋率。 相似文献
11.
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
12.
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
13.
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
14.
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
15.
Fouad N. Ibrahim Dr. 《GeoJournal》1988,17(1):133-141
Taking the example of W Sudan, an analysis of the climatic incidents leading to the two recent famine disasters is made. On this natural background, the human side is investigated. Focus is directed towards the fragile economic structure of the famine-prone population groups. An early-warning system for famine in the Sahelian Zone is proposed taking grain production and storage, livestock development and the relationship between the prices of livestock and grain as major indicators. 相似文献
16.
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
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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
20.
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