纳米石墨粉对红黏土力学性质的影响

对添加了纳米石墨粉的红黏土以击实进行了重塑样制备,设计了不同掺量纳米石墨粉在红黏土最优含水率下的三轴固结不排水试验;通过应力-应变曲线,分析了不同掺量纳米石墨粉对红黏土力学性能的影响,得出了抗剪强度和抗剪强度指标的规律,并采用SEM微观手段对其改善机理进行了分析。试验结果表明:抗剪强度和黏聚力C随纳米石墨粉掺量的增加先增加后减小,内摩擦角$\varphi $基本保持不变,得出适量的纳米石墨粉对红黏土的力学性质有显著的提高,最优掺量在1%~2%之间。研究认为,纳米石墨粉红黏土呈现出的力学性质,与纳米石墨粉对红黏土孔隙结构的影响、纳米石墨粉对红黏土颗粒的黏附胶结密切相关。     

纳米碳酸钙影响下红黏土强度特性试验研究

为了探寻纳米碳酸钙对桂林红黏土力学强度特性的影响机理,利用TSZ-1型三轴试验仪进行不固结不排水三轴压缩试验,分析了在不同干密度条件下各梯度纳米碳酸钙掺量对重塑红黏土黏聚力、内摩擦角、抗剪强度以及应力-应变曲线的影响,从红黏土矿物颗粒胶体化学的角度阐释纳米碳酸钙对红黏土力学强度的影响机理,研究结果表明:随着纳米碳酸钙掺量增加,红黏土黏聚力、内摩擦角以及抗剪强度呈现先减小后增大的趋势;纳米碳酸钙的掺入改变了原有的介质电荷pH值,使得红黏土原有的氧化铁胶结吸附平衡发生改变,形成新的钙质胶结团粒,改变了红黏土的强度特性;加入纳米碳酸钙后起始干密度为1.4g ·cm-3的重塑红黏土样应力-应变曲线由弹性理想塑性型变为应变硬化型。     

粉煤灰和二灰对桂林红黏土力学性质的影响

为了研究粉煤灰和二灰掺量及养护时间对桂林红黏土的改良效果,进行了直剪试验、固结试验以及电镜扫描试验。试验结果表明,粉煤灰的掺入提高了红黏土的抗剪强度,但超过一定量（18%粉煤灰掺量）反而会降低红黏土黏聚力,各掺量粉煤灰红黏土随养护龄期的延长,抗剪强度呈先增后缓趋势。二灰改良红黏土,在早期强度剧增,且强度随养护时间增长而大幅增加,一定龄期内,二灰红黏土黏聚力随二灰掺量呈先增后减趋势。粉煤灰和二灰的掺入均增大了红黏土的压缩模量,且随养护时间的延长而逐渐增大。红黏土中随粉煤灰、石灰的加入,发生一系列物理化学反应,从微观结构分析得知土中孔隙减少,结构性较素红黏土好。     

柴油污染重塑红黏土直剪力学特性试验研究

广西红黏土分布区柴油泄漏对土体造成了一定程度污染,为研究轻质非水相非极性柴油孔隙液对红黏土力学性质的影响,本文以0#柴油为添加剂对其重塑样进行不排水快速直剪试验,测得了不同含水率、含油率、法向压力下红黏土抗剪强度及其参数变化规律。研究结果表明:在土-水-油系统中,非极性柴油孔隙液对红黏土强度影响相对较小,且受含水率影响。同一含油率时,红黏土抗剪强度、内摩擦角、黏聚力均随含水率增加而降低;同一含水率时,法向压力影响柴油作用模式,随含油率增加,抗剪强度参数变化较为复杂,当含水率为20%,红黏土内摩擦角、黏聚力反向波动变化;同一含湿率时,柴油比例的提高导致红黏土抗剪强度参数的增大。扫描电镜观察发现,非极性柴油孔隙液的介入,改变了水-土系统的静电及结构模式,导致红黏土强度发生变化,通过所建的“多尺度多阶段柴油作用微结构模型”,阐明了柴油孔隙液对红黏土强度特性影响的微观机理。     

木质素纤维红黏土强度及变形特性试验研究

利用工业废料改良土体性能不仅具有实用价值而且能够保护环境。采用室内土工试验及SEM试验,针对木质素纤维加筋红黏土的效果,以及木质素纤维掺量对红黏土强度及变形特性的影响规律和作用机理进行研究。试验结果表明:木质素红粘土压缩模量随着纤维掺量的增加先增加后减小,2%纤维掺量时,模量最高;不同木质素掺量红粘土的内摩擦角基本保持不变;红黏土黏聚力随木质素掺量的增加先减小后增大再减小。2%是纤维最优掺量,土体黏聚力出现最大值;在三轴实验中,加筋红黏土试样均发生鼓胀变形,没有明显的破裂面,具有典型的应变硬化特征。研究结果表明木质素纤维能一定程度提高红粘土的强度,提升红粘土的工程应用价值。      

垃圾填埋场污泥灰改性黏土衬垫的强度特性及微观结构

为评价污泥灰改性黏土作为填埋场衬垫防渗材料的可行性,分析污泥灰改性黏土强度特性及孔隙结构,针对受垃圾渗沥液腐蚀的纯黏土与污泥灰掺量为1%～5%的改性黏土,采用直接剪切试验分析其抗剪强度变化规律,采用低温氮气吸附试验分析剪切变形后试样的孔隙结构组成。结果表明,改性黏土属于VI型等温线,并存在H3型滞后环,且2～6 nm介孔的数量占比较大。受垃圾渗沥液腐蚀后,黏土抗剪强度大幅下降,黏聚力与内摩擦角分别下降60.12%和19.17%;黏土的最大氮气吸附量降低16.19%,且孔隙分布双肩峰发育不完全;随污泥灰添加量的增加,改性黏土抗剪强度增大,且孔隙分布逐渐恢复双肩峰形式,总孔容增大。     

生石灰改良黄土的微观机制试验研究

为探究石灰掺量对黄土强度的影响规律及其微观机制,采用不同比例的生石灰对黄土进行改良。开展了直剪试验、压汞试验及扫描电镜测试,定性和定量分析素黄土及不同石灰掺量改良黄土的强度特性和微观结构变化规律,并对石灰改良黄土的微观机理进行较为深入的分析。结果表明:石灰改良黄土的抗剪强度参数随着石灰掺量的增大出现先增大再减小的变化规律,在石灰掺量约为8%时,其黏聚力和内摩擦角达到最大值;石灰的掺入使黄土骨架颗粒之间及其表面附着的胶结物逐渐增多,孔隙被胶结物质填充,土体中的不稳定孔隙逐渐减少,整体性增强;但当石灰掺量过大时,多余的石灰会堆积于团粒之间,影响团粒之间的胶结。石灰改良黄土强度提高的原因是石灰水化反应生成的胶结物质增强了土颗粒之间的胶结程度,增大颗粒间的相互摩擦,使土体结构更加稳定,提高土体强度;石灰掺量过高时,改良黄土抗剪强度降低是因为过量的石灰影响了土颗粒之间的胶结作用。研究成果既是对黄土强度特性及微观结构理论研究的丰富与充实,又可以为改良黄土工程设计的相关参数选取提供参考依据。      

不同剪切速率对风化砂改良膨胀土抗剪强度指标的影响

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。     

广吸力范围内压实红黏土的强度特性

为了研究广吸力范围内红黏土的强度特性,采用经压力板法饱和,对盐溶液蒸汽平衡法吸力平衡后的非饱和桂林红黏土样进行一系列常含水率直剪试验。高吸力时土–水特征曲线不受土体密度的影响,故等含水率试验可以认为是等吸力试验。试验结果表明,随着平衡吸力的增加,非饱和红黏土的抗剪强度与黏聚力均先增大后减小,吸力为7 MPa左右时出现抗剪强度的最大值;当吸力超过7 MPa后内摩擦角基本保持不变,说明高吸力阶段吸力增大引起的强度变化是由黏聚力的变化引起的;吸力超过70 MPa后随着吸力的增加,强度变化较小。最后结合压汞试验的结果,从孔隙大小分布的角度解释了红黏土在广吸力范围内的强度特性。     

纤维红黏土强度的正交试验及多元非线性回归分析

纤维长度、纤维掺量、含水率和干密度是纤维红黏土强度的主要影响因素,采用正交试验设计方法,研究多因素耦合作用对纤维红黏土抗剪强度指标c,φ的影响,通过对试验结果进行极差、方差分析,确定了c,φ的最优制备工艺及各影响因素的显著性大小。基于多元非线性回归理论,应用SPSS软件建立了多因素与纤维红黏土c,φ的多元非线性回归模型。试验和分析结果表明:4个因素对纤维土c,φ的影响主次顺序均为:含水率>干密度>纤维掺量>纤维长度,其中含水率对c影响显著,干密度与纤维掺量对c有一定的影响,而φ受含水率影响明显,其它因素对其影响不明显,各因素水平的改变对c的影响程度大于对φ的影响。对c,φ的多元非线性回归模型验证发现,c,φ模型的相关系数较高、显著性较强、且预测值与实际值之间线性关系明显,确定了模型的可靠性。研究成果为进一步研究纤维改善红黏土的工程特性、固化机理具重要指导意义。     

Unity of the national and the international in the socio-cultural development of the peoples of the USSR

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.     

Report of the restudy of the defined global stratotype of the base of the Silurian System

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.     

Deviation of the major axis of the inertia ellipsoid of the Moon from the direction toward the Earth

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″.     

The Tendencies of the Development of the Mineral-Resources Sector at the Turn of the Century

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.     

Causes of the famine among the rural population of the Sahelian zone of the Sudan

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.     

东濮凹陷北部沙河街组三段中亚段沉积环境分析

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。     

On the consistency of proposed models for the Pyrenees with the structure of the eastern parts of the belt

The structure of the eastern Pyrenees consists mainly of south-directed thrusts involving basement and cover rocks. An antiformal stack developed by the piling up of basement thrust sheets which outcrop in the Axial zone. These structures account for a thin-skinned thrust model rather than a vertical fault model in which the Axial zone would be essentially autochthonous, and the North-Pyrenean fault the axial plane of a fan thrust system. New data from the Eastern Pyrenees and the thin-skinned model suggest that(1) the structure east of the Pedraforca nappe is similar to that of the Central Pyrenees; (2) the cover rocks of the South-Pyrenean units and of the Axial zone-after restoration—built up a northwards-thickening prism consistent with the existence of a unique Pyrenean sedimentary basin during Mesozoic time; (3) the Axial zone is only a complex antiformal stack developed as a part of South-Pyrenean system related to the Paleogene thrusting-tectonics. The Axial zone palaeogeographic area had no special meaning during Mesozoic time.     

The Importance of the Precipitation and the Susceptibility of the Slopes for the Triggering of Landslides Along the Roads

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.