Propagation characteristics of a blast-induced seismic effect in the beds of structures during construction of the dam at the No. 2 Kambaratinskaya HPP-2

The propagation characteristics of blast-induced oscillations in slightly cohesive cover soils and rocks are examined during construction of the No. 2 Kambaratinskaya HPP. A selective empirical evaluation of the dynamic characteristics of the entities is given on the basis of spectral analysis of vibrations recorded in their beds and structures. The distribution of process parameters over the area covered by seismometric observations in the Kirgiz Republic is recommended as initial base information for evaluation of the seismic effect of a large-scale blast.     

The effect of bed age and shear stress on the particle morphology of eroded cohesive river sediment in an annular flume

Erosion experiments were conducted in an annular flume to determine the effect of bed age and shear stress on the particle morphology (fractal dimensions D, D(1), and D(k)) of eroded cohesive river sediment. Sediment beds were deposited under low shear and left to consolidate for one, two and seven days. Fractal data and photomicrographs show particle morphology changed with shear stress and bed age. During the one-day experiment, flocs were highly branched and particle geometry became more complex with increasing shear. Microflocs present in suspension at low shear, formed larger more loosely bound flocs at moderate shear due to flocculation. At higher shear, larger flocs were less prevalent due to particle breakup. As bed age increased, less sediment was eroded and particles appeared less porous and more angular in shape for a given shear stress. Changes in floc morphology and eroded sediment mass at various shear stresses may be related to bed age-associated biostabilization of bed deposits.     

非饱和黏性土粒间吸力测试研究

对粒间吸力的认识是非饱和土有效应力及变形、强度特性研究的基础。由粒间吸力各组成部分的特点 ,提出了非饱和黏性土粒间吸力的测试原理和方法 ,并对红黏土的粒间吸力进行了试验。此研究对于结构性与土的力学性质间关系的研究有重要意义     

Experimental Investigation and Analysis of the Settlement Funnel in Beds Supporting Different Types of Foundations

A solution is given for determination of the stresses in a foundation bed, which is represented by a linearly deformable half space and intended for foundations with circular or square lower surfaces extending beyond the limits of the loaded area. Experimental data on the settlement funnel in homogeneous and layered beds are presented. The dependence of the spread of the settlement funnel on the dimensions of the plate is established.     

上三公路5#滑坡稳定性分析

选择3个不同剖面,对上三公路5#滑坡稳定性进行分析。结果表明:在厚度大的松散堆积土层路基中,第四系松散堆积物与基岩风化带接触部位往往会成为斜坡破坏的潜在滑动面;降雨将使边坡稳定系数降低。根据分析结果,提出了对不稳定地段预应力锚索加固治理方案。     

土的卸载体缩的试验研究及其机理探讨

在土的三轴试验中卸载体缩现象普遍存在。卸载体缩随着围压的增加呈下降趋势。不同土和同样土在不同密度下卸载体缩的现象和原因不同。密砂的卸载体缩是剪胀可恢复的宏观体现。松砂的卸载体缩则分为两种 ,一种是塑性体缩的组成部分 ,在加载初期出现 ;另一种则是剪胀可恢复部分 ,随着剪应力的提高而出现。对于粘土 ,卸载体缩完全是塑性体缩 ,表明粘土的结构性随着加卸载过程而遭到破坏。     

Characteristic features of loess beds for elevator structures

Conclusions The method that we developed for computing loess foundation beds for elevator structures makes it possible to obtain contact stresses and settlements of the structure with consideration of the effect of multiple loading-unloading and nonuniform wetting of the bed on the mechanical properties of the bed soils. The proposed method permits investigation of the bed deformation of silo structures and contact stresses; this makes it possible to improve the reliability and accuracy of bed designs and the computation of settlements for elevator structures on loess soils prone to slump-type settlement. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 2, pp. 18–20, March–April, 1990.     

Causes of the loosening and failure of soils beneath plates

S. S. Vyalov's's idea that microcrack development is the cause of the loosening of soils is used. Results of computational determination of the moment of initiation and development of microcracks in frozen sandy and cohesive soils in the beds of rigid cylindrical plates are presented. A comparison is made with data derived from experimental investigations. It is established by calculations that plastic shears and microcracks created by ultimate tensile stresses are the cause of widespread loosening and failure of sandy beds beneath plates. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 6, pp. 25–29, November–December, 2008.     

The frost resistance of coarse-grained soils as one of the properties determining their suitability for earth-dam constructions

The earth-dams in the mountainous regions of Poland are working under very specific, severe, climatic conditions. The daily variations of temperatures submit subsurface soil strata to frequent cyclic freezing and thawing, that leads to the destruction of the initial structure of the soil. It leads to the conclusion that we have to forecast the changes which in course of time can follow in the soil used in the structure. In the paper the methodology of frost resistance tests is described and the results obtained in course of the tests are given. These results are connected with the situation of the soil bed along the river and the level of terraces, as well as with such other properties as particle size distribution, degree of roundness, degree of weathering. The tests were carried out in two different negative temperatures, that enabled the establishment of the influence of temperature disintegration of grains. Different types of disintegration depending on the origin of the rock type are described.     

夏热冬暖气候区医院门诊楼能耗评价指标研究

医院建筑能耗逐年升高,其中空调能耗占总能耗比例较大。在医院建筑的节能改造或能耗状况分析中,多数以单位建筑面积、门诊人数、床位数的能耗来评价医院能耗的高低。以夏热冬暖气候区医院门诊楼为研究对象,通过理论分析建立建筑负荷分析模型,设计建筑负荷正交模拟实验,利用模拟软件De ST进行负荷模拟,研究建筑面积、床位数、门诊量/床位数、医院类型对建筑全年总负荷的影响,模拟结果表明:建筑面积(床位数)越大,门诊量/床位数越大,未开展预约门诊的医院的年总负荷越大,反之越小。建筑年总负荷影响因素的主次顺序为门诊量/床位数建筑面积(床位数)医院类型,其中门诊量/床位数、建筑面积(床位数)对年总负荷影响显著(P0.05);医院类型对年总负荷影响不显著(P0.05)。建议采用人均单位面积能耗占用床位数指标来评价门诊楼的能耗,更加科学。     

Of the necessity of knowledge of the natural pedo-geochemical background content in the evaluation of the contamination of soils by trace elements

In order to evaluate the contamination of the Dornach (Switzerland) site within the framework of the CEEM-Soil project, each participating team was allowed to take a maximum of 15 samples. The French team's sampling was organized in such a way as to answer the following questions: (i) what is the natural concentration of the soils at this site (local pedo-geochemical background content)?; (ii) what are the levels of Cd, Cu, Pb and Zn contamination of the soil?; (iii) what is the depth reached by the surface contamination that is derived from atmospheric fallout?; (iv) how is the contamination spread along the longest axis of the area under study? The relationships between total Fe and the trace metals have allowed local variations in the natural pedo-geochemical background content to be detected and thus permitted the anthropogenic contamination to be estimated. There would appear to be a low level of Pb contamination over all the site investigated (an increase of the order of 5-10 mg kg(-1) on the background level), limited to the surface humus-bearing layers. There is also a significant contamination by Cu over all of the site (an increase of the order of 30-40 mg kg(-1)). This contamination has remained in the surface horizons (0-20 cm). Very high Zn and Cd concentrations have been found in the four surface (0-4 cm) and deep horizons (15-70 cm) taken under the forest and very much lower values in the samples taken from cultivated soils. The most likely explanation is an unequal inheritance between the upper part of the site (wooded with thinner very clayey soils) and the lower cultivated part of the site (with thicker less clayey soils developed in a loamy material). For various reasons, it seems unlikely that a contamination of the wooded part should be so much higher than the cultivated part due to the interception of atmospheric dust by the trees. The local pedo-geochemical background Cd and Zn content of the upper wooded part proved to be clearly higher than that which would be encountered in most soils of Switzerland and France. Given this evaluation of the background content, it seems that only the surface horizons have been affected by Zn contamination (an addition of approx. 60-100 mg kg(-1)). In the case of Cd, the increase in concentrations is only 0.5-1 mg kg(-1) for the ploughed horizons, as well as the for the A horizons.     

Computing the settlements of foundations placed on beds with layers of weak clayey soils

Conclusions 1. In designing natural foundation beds with layers of weak clayey soils, the final settlements of the foundations and the settlements with time can be computed using the theories of elasticity and seepage consolidation in accordance with the method outlined in the paper. This is confirmed when additional (over and above the natural) pressure p₀ 5c are applied to the top of the weak clays, where c is the minimum specific cohesion of the clayey soils as determined with allowance for the possible reduction in cohesion with time. When p₀ > 5c, including pressures on the roof of the weak clays equal to the design pressures given in Section 3.62 of SNiP II-15-74, there are only isolated cases of building construction from which it is impossible to judge laws governing bed deformation.2. In conformity with Section 1, the method of computation clarifies the computation of settlements as compared with SNiP II-15-74, simplifying the design of beds with layers of weak clayey soils.Scientific-Research Institute of Bases and Underground Structures (NIIosnovanii). Estonian Institute of Industrial Design and Planning. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 4, pp. 15–18, July–August, 1981.     

Results of investigation of the stress state of a sandy bed for rigid plates

Conclusions 1. As compared with corresponding solutions of the theory of elasticity, significant stress concentration is observed in compacted and loose sandy beds under any vertical load along the central vertical of rectangular plates. The degree of stress concentration depends on the properties of the medium (the density of the sand), the shape of the plate (the relationship between the dimensions of its sides), the external load, and, evidently, on a number of other factors. In the cases under consideration, the stresses increased nearly proportionally to the load (simple loading).2. Maximum vertical deformations of the sandy bed under small loads occur directly at the lower surface of the plates. As the load increases, maximum deformation appears at a certain depth below the lower surface of the plate. The relation between stresses and relative vertical deformations is nonlinear over the entire range of load variation.3. The more precisely defined results of study of the stress-strain state of the bed make it possible to evaluate more reliably the validity of existing and newly developed theoretical solutions employed in designing beds from first and second groups of limiting states.Novosibirsk Civil Engineering Institute. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 3, pp. 24–27, May–June, 1981.     

砾性土层液化的触发条件

天然沉积砾性土场地液化是一个超出现有认识与现有规范的新问题,其触发条件至关重要,从震害现场调查提炼出相关认识最为可靠,是后续研究的基础和导引。鉴于2008年汶川地震砾性土液化规模远超以往,以其调查结果为主,综合历史砾性土液化全部资料,提出砾性土层液化的触发条件。现有资料分析表明:0.15g应为触发天然沉积砾性土层液化的地表最低地震强度,大规模砾性土层液化发生则需要0.2g~0.4g(Ⅷ度区)的地震强度;松散和接近松散状态是天然砾性土层液化的基本条件,液化砾性土密实度可随地震强度增大而增高但仍以稍密状态为上限;液化砾性土含砾量可达85%及更大,并且不随地震强度减弱而降低;高剪切波速天然砾性土层会发生液化,砾性土与砂土密实程度的剪切波速分界线相差悬殊,砂土液化判别公式不适于砾性土层;上覆渗透性差非液化土层(帽子)的存在是地下砾性土层可发生液化的必要条件,可称为帽子效应,此厚度至少应为0.5 m;地下水位与帽子间不能有过厚的可排水层间隙也是下卧砾性土层可发生液化的必要条件,可称为间隙效应,此间隙上限可取为2.0 m;区别于砂土液化判别方法,砾性土液化判别需要埋藏条件方面的特殊要求,否则容易出现误判。     

循环流化床锅炉快速床流体动力学研究

分析了快速床区流体动力学特征 ,通过实验研究了固体颗粒循环率、气体速度等影响快速床区动力学的主要因素 ,找出快速床区悬浮粒子密度纵向和横向分布规律 ,用回归方法得出相应计算公式。     

Influence of internal biogas production on hydrodynamic behavior of anaerobic fluidized-bed reactors

Predictive models for describing the hydrodynamic behavior (bed-expansion and bed-pressure gradient) of a three-phase anaerobic fluidized bed reactor (AFBR) was developed according to wake theory together with more realistic dynamic bed-expansion experiments (with and without internal biogas production). A reliable correlation equation for the parameter k (mean volume ratio of wakes to bubbles) was also established, which is of help in estimating liquid hold up of fluidized beds. The experimental expansion ratio of three-phase fluidized beds (E(GLS)) was approximately 18% higher than that of two-phase fluidized beds (E(LS)); whereas the experimental bed-pressure gradient of the former [(-DeltaP/H)(GLS)] was approximately 9.3% lower than that of the latter [(-DeltaP/H)(LS)]. Both the experimental and modeling results indicated that a higher superficial gas velocity (u(g)) gave a higher E(GLS) and a higher E(GLS) to E(LS) ratio as well as a lower (-DeltaP/H)(GLS) and a lower (-DeltaP/H)(GLS) to (-DeltaP/H)(LS) ratio. As for the operation stability of the AFBR, the sensitivity of u(g) to expansion height (H(GLS)) and (-DeltaP/H)(GLS) is between the sensitivity of superficial liquid velocity and biofilm thickness. The model predictions of E(GLS), (-DeltaP)(GLS), and (-DeltaP/H)(GLS) agreed well the experimental measurements. Accordingly, the predictive models accounting for internal biogas production described fairly well the hydrodynamic behavior of the AFBR.     

Inspection of foundations for the Rostral Columns of Saint Petersburg and analysis of their bed deformations

The design and foundation bed of the Rostral Columns are ascertained, the soils in their beds are analyzed, the settlement of the columns is calculated, the basic causes of column tilt are indicated, and future work on the beds and foundations is assessed. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 4, pp. 16–19, July–August, 1999.     

饱和黏性地层中基坑坑底抗隆起稳定验算方法

针对饱和黏性土地层中基坑坑底抗隆起稳定性验算,首先建议其强度指标取原状土样在有效自重应力下预固结的不固结不排水抗剪强度cu,随后考虑该不排水抗剪强度随深度近似线性增大的特点,给出相应地基承载力的计算公式。进而在作者此前所提出的坑底抗隆起稳定性验算方法基础上,给出饱和黏性土地层中深基坑坑底抗隆起稳定安全系数的计算方法,包括挡土构件嵌深较小情况下按地基承载力的验算方法,嵌深较大情况下按圆弧滑移面的验算方法和识别过大嵌深的临界嵌深计算公式,并通过与精细数值方法计算结果的对比,对所提出方法及公式的正确性和精度进行了检验。文中还给出两个工程实例,展示了实际分层地基,特别是既有黏性土也有无黏性土层时按所提出方法的坑底抗隆起验算。     

Explanation of Cyclic Mobility of Soils: Approach by Stress-Induced Anisotropy

In this paper, a new constitutive model is proposed to describe the mechanical behaviors of soils under different loading conditions. New evolution equations for the development of stress-induced anisotropy and the change of overconsolidation of soils are proposed. By combining systematically the above two evolution equations with the evolution equation for the structure of soil proposed by Asaoka et al. (2002), the newly proposed model is able to describe not only the mechanical behavior of soils under monotonic loading, but also the behavior of soils under cyclic loading with different drained condition. Special attention is paid to the behavior of sand subjected to cyclic loading under undrained condition. That is, for given sand with different densities, very loose sand may liquefy without cyclic mobility, medium dense sand will liquefy with cyclic mobility while dense sand will not liquefy, which is just controlled by the density, the structure and the anisotropy of the sand. A suitable model should uniquely describe this behavior without changing its parameters. Present research will show the possibility of the proposed model.