地震场地的综合评定方法

本文给出了一个考虑场地土层的刚度、覆盖土层厚度及软弱夹层、液化土层等因素对场地地震动影响的综合评定方法。该方法根据场地土层的刚度和覆盖土层的厚度，按模糊评判方法确定场地指数μ值，并建立μ值与设计地震反应谱的关系。当场地指数确定时，就可确定用于抗震设计的反应谱。对于场地土层中含有软弱夹层或液化土层的情况，本文还给出了考虑这些影响因素，对场地指数或设计地震动参数进行修正的方法。     

Discriminant Model for Evaluating Soil Liquefaction Potential Using Cone Penetration Test Data

Statistical analysis using a discriminant model is applied to 399 cone penetration test (CPT) data sets of both liquefaction and nonliquefaction cases, including 174 sets from the Chi-Chi earthquake in Taiwan and 225 sets of synthesized data. The discriminant model employed is a multivariate statistical method. In situ testing results of cone tip resistance qc and sleeve friction ratio Rf are adopted as the major parameters for analyses. A model for evaluating liquefaction potential using CPT-qc data is also established in this study, which allows calculated results to be compared with the empirical curves.     

MASS TRANSFER EFFECTS IN LIQUEFACTION OF COAL BY SRC-II PROCESS PART I EFFECT OF MIXING POWER

A correlation between the volumetric hydrogen mass transfer coefficient (K_La) in SRC-II process slurry and specific power consumption in mixing (E/V_R) is developed. This correlation is independent of reactor configuration and it is also in very good agreement with the literature correlations for K_La. It is unified with an intrinsic hydrogen reaction rate expression to simulate the rate of hydrogen consumption in the SRC-II process. The simulation is validated by experimental data from an SRC-II continuous stirred tank reactor (CSTR). The mass transfer effects are interpreted and related to changes in product quality and a reduction in hydrogen reaction rate. Critical mixing power, required to maintain kinetically controlled operation of the process, is suggested.     

The nature of the synergistic effect of binary tetralin-alcohol solvents in Kansk-Achinsk brown coal liquefaction

Kansk-Achinsk brown coal hydrogenation and swelling in tetralin, in low molecular alcohols, in other solvents and in binary mixtures were studied. Tetralin was found to be the most effective liquefaction solvent, but methanol and ethanol were the active ones in coal swelling. Synergistic effects were observed when the mixtures of tetralin and methanol or ethanol were used for liquefaction and swelling. The effect of binary solvents was shown to be due to the ability of alcohol components to cause brown coal to swell improving the availability of the fragments of coal matter for the reactive hydrogen donor tetralin molecules.     

MICROBIALLY FORMED CATALYSTS FOR ENHANCEMENT OF DIRECT COAL LIQUEFACTION

The present study examines the potential to biologically precipitate active catalytic compounds on the surface of coal particles in a water slurry. These compounds could be active forms of iron, an element abundant in coal, or active forms of molybdenum added as a soluble salt. The acidophilic microorganisms Thiobacillus ferrooxida/ns and Acidianus brierlyi were added to a 5% coal slurry at a pH of 3·0 or less. Experiments were carried out for 21 days in shake flasks/automated fermentor at constant temperature and pH. Deposition of iron and molybdenum compounds on the particle surface was confirmed by several spectroscopic methods. After bio-treatment, the coal was removed by filtration and dried. A sample was then liquified in a bomb at 385°C in tetralin and hydrogen for 15 minutes. In some runs the sulfiding agent dimethyl disulfide (DMDS) was added to the mixture. Separation of the products was by soxhlet extraction. Total conversion, gas + oil + asphaltenes + preasphaltenes, of the pretreated coal was compared with the conversion of raw, untreated coal. Statistically significant increases in conversion were achieved for various pre-treatment methods. The maximum conversion achieved was with coal pre-treatment in the presence of Acidianus brierleyi, and with the addition of 200 mg/1 of ammonium molybdate to the slurry. Under these conditions, liquefaction of 2 separate runs, in the presence of DMDS, produced conversion of 78 and 81%. This compared with 48% conversion for the raw coal under the same liquefaction conditions.     

DIRECT BIOMASS LIQUEFACTION BY AN EXTRUDER-FEEDER SYSTEM

A new type of extruder-feeder to a reactor system has been developed, designed and experimentally-tested for direct biomass liquifaction under high temperatures and high pressure conditions. Solid form mixtures of up to 50 wt % wood flour in carrier oils were pumped into a reactor system of up to 430°C temperature using a single screw extruder and producing pressures of up to 20.7 KPa in the reactor. Wood oil distillates with oxygen content in the range of 5-12 wt % were obtained from the reaction of Birch wood flour which contains 41.3 wt % of oxygen. This results in a crude wood oil with a heating value of about 9,000 Kcal/kg, compared to about 4,500 Kcal/kg for the wood. Details on the liquefaction process, the experimental facility and its performance, the experimental procedure and operational data and the analytical results of the feedstock and products are given.     

The relation between the state indices and the characteristic features of undrained behaviour of silty sand

The characteristic features of a series of isotropically and K₀-consolidated undrained triaxial compression behaviour of a silty sand were investigated for a range of initial void ratio ($e)$ and mean effective confining stress ($p^{\prime }$). The silty sand used in this study contained about 10% natural fines. The critical state line (CSL) of K₀-consolidated specimens, K₀U was slightly lower than the CSL for isotropically consolidated specimens, CIU. The respective CSLs for K₀U and CIU were used to define state indices, such as state parameter ($\psi )$, state index ($I_s$), state pressure index ($I_p$) and modified state parameter (${\psi }_m$), within critical state soil mechanics (CSSM) framework. It was found that each state index exhibit a unique relation with liquefaction potential, irrespective of consolidation type, however different relationships were observed between state indices and the stress ratio at the triggering of liquefaction, ${\eta }_{\mathit{IS}}$ or the liquefaction resistance, $q_{\mathit{IS}}$. The correlation of characteristic features of undrained shearing (i.e., liquefaction potential, ${\eta }_{\mathit{IS}}$ and $q_{\mathit{IS}}$) and drained shearing (maximum rate of volume change, ${\left(d{\epsilon }_v/d{\epsilon }_a\right)}_{\mathit{m}\mathit{a}\mathit{x}}$) with state indices were compared statistically in terms of root mean square deviations (RMSD). All characteristic features of undrained shearing generally showed the best correlation with $I_p$ in term of RMSDs, however $\psi$ showed comparatively wider scatter for the specimens showing flow and limited flow behaviour.     

Engineering geological characteristics of the 1998 Adana-Ceyhan earthquake, with particular emphasis on liquefaction phenomena and the role of soil behaviour

 The Adana-Ceyhan earthquake (M_s=6.2) occurred in the southern part of Turkey on 27 June 1998 and resulted in the loss of 145 lives and extensive damage to buildings in Ceyhan town and the settlement areas in its vicinity. Soil liquefaction, ground failure due to lateral spreading and rock falls occurred. The area of Adana is characterised by a large alluvial basin with a delta shape. Most of the basin is filled with Quaternary recent Holocene deposits. The recent rapid deposition of sediments and the very shallow groundwater table throughout the basin create conditions conducive to liquefaction. The results of a preliminary investigation of soil liquefaction caused by the earthquake and liquefaction assessments based on field performance data are presented together with evaluations concerning the likely contribution of the soils to the damage sustained by buildings. The results of the liquefaction susceptibility analysis indicated that the data from the liquefied sites were within the empirical bounds suggested by the field-performance evaluation method. It was also shown that shallow sand layers should have liquefied and the surface disruption observed on the site could be predicted by the bounds used for the relationships between the thickness of liquefiable sediments and the overlying non-liquefiable soil. Site-response analyses based on acceleration response spectra from the actual earthquake's strong motion records revealed that soil behaviour was one of the most significant factors in the damage to buildings caused by the earthquake. Received: 4 January 2000 · Accepted: 28 March 2000     

A study of liquefaction related damages on shield tunnels

Studies of liquefaction-related damages on underground structures are limited and sometimes controversial. Liquefaction potential analysis is essential in tunnel design in liquefiable soils. A Taipei Rapid Transit System (TRTS) tunnel site in Taipei County was selected to study the risk under liquefaction-related damage. The liquefaction risk index was applied for assessment of the overall liquefaction risks and liquefaction-induced settlement at the interest site. The anti-liquefaction measure for shield tunneling by using secondary injection grouting was discussed to eliminate the flow of liquefied soils and reduce the liquefaction-induced settlement.     

Exploring the possibility of assessing the damage degree of liquefaction based only on seismic records by artificial neural networks

This study presents a new approach to determine the damage degree of liquefaction caused by a large earthquake. We propose an artificial neural network (ANN) model based only on the seismic records of ground and define the degree of liquefaction “DDL” as a damage index. This ANN model predicts the degree of excess pore water pressure increase as the correct output label based on the seismic records obtained from the three-dimensional shaking table test. The proposed model achieved high accuracy, and the outcomes from training data indicated that the ANN model is suitable to function as a liquefaction assessment system. Further, to evaluate the applicability of the proposed ANN model in the real world, the datasets of waves from three actual seismic records were input to the ANN as validation data. The DDL judgment obtained was a good fit with the real phenomena observed.