地球物理场探测的新尝试

1994年美国联邦政府根据国会批准的关于关闭一些军事甚地和实验室计划的精神,批准了把实验室从研究功能转变成可以进入市场形态的计划.这项决定涉及到联邦政府和能源部进行核武器研究的劳伦斯·利弗莫尔等11个国家实验室.     

A study of the weathering of the Bukit Timah granite Part B: Field and laboratory investigations

Field investigations consisting of surface seismic refraction and electrical resistivity surveys, drilling and downhole geophysical logging of the rock mass and of the residual soil indicate that the weathering of the Bukit Timah granite has been rapid and is primarily caused by chemical decomposition due to the tropical climate in Singapore. The granite is usually overlain by a thick layer of residual soil. Laboratory tests indicated a large reductions of the material strength, the modulus of elasticity, the rock mass quality and other mechanical properties of the weathered granite. Apart from the mechanical properties of the residual material and/or of the weathered granite rock, physical properties including density, water content, Atterberg's limits, grain size distribution, permeability, sonic velocity and electrical resistivity were also studied in order to assess the weathering grade and the weathering processes.     

工程物探方法在岩石风化程度判别中的应用

结合某电厂工程地质条件,运用波速试验、高密度电阻率法(直流电法)和地质雷达测试(电磁波法)等物探方法,较好地判别了基岩风化程度的整体分布范围及软弱岩土层的分布区域,并通过工程地质调查及钻探验证,证实了工程物探能快速、真实、准确地反映基岩风化程度,以指导后期基础设计及基坑开挖。     

地球物理勘探技术在煤炭勘探领域中的应用

针对当前煤田地球物理勘探的技术、方法、特点等进行了详细的阐述,并对多波多分量地震勘探、矿井高密度直流电法、矿井瞬变电磁法及地质雷达多种技术和方法进行了说明,以更好的预测预报致灾地质因素。     

深圳市赛格群星广场花岗岩强风化带承载力试验研究

提供了深圳市赛格群星广场花岗岩强风化超重型动力触探和钻孔内深层平板载荷试验的实测结果，讨论了应用超重型动力触探划分风化带的可行性，并对场地强风化带3个亚层(土状、砂砾状、块状强风化带)的桩端承载力取值进行了补充，为桩基础设计提供了可靠参数。     

Machine learning and data-driven prediction of pore pressure from geophysical logs: A case study for the Mangahewa gas field,New Zealand

Pore pressure is an essential parameter for establishing reservoir conditions, geological interpretation and drilling programs. Pore pressure prediction depends on information from various geophysical logs, seismic, and direct down-hole pressure measurements. However, a level of uncertainty accompanies the prediction of pore pressure because insufficient information is usually recorded in many wells. Applying machine learning (ML) algorithms can decrease the level of uncertainty of pore pressure prediction uncertainty in cases where available information is limited. In this research, several ML techniques are applied to predict pore pressure through the over-pressured Eocene reservoir section penetrated by four wells in the Mangahewa gas field, New Zealand. Their predictions substantially outperform, in terms of prediction performance, those generated using a multiple linear regression (MLR) model. The geophysical logs used as input variables are sonic, temperature and density logs, and some direct pore pressure measurements were available at the reservoir level to calibrate the predictions. A total of 25,935 data records involving six well-log input variables were evaluated across the four wells. All ML methods achieved credible levels of pore pressure prediction performance. The most accurate models for predicting pore pressure in individual wells on a supervised basis are decision tree (DT), adaboost (ADA), random forest (RF) and transparent open box (TOB). The DT achieved root mean square error (RMSE) ranging from 0.25 psi to 14.71 psi for the four wells. The trained models were less accurate when deployed on a semi-supervised basis to predict pore pressure in the other wellbores. For two wells (Mangahewa-03 and Mangahewa-06), semi-supervised prediction achieved acceptable prediction performance of RMSE of 130–140 psi; while for the other wells, semi-supervised prediction performance was reduced to RMSE > 300 psi. The results suggest that these models can be used to predict pore pressure in nearby locations, i.e. similar geology at corresponding depths within a field, but they become less reliable as the step-out distance increases and geological conditions change significantly. In comparison to other approaches to predict pore pressures, this study has identified that application of several ML algorithms involving a large number of data records can lead to more accurate prediction results.     

Characterisation of the weathering profile developed over a porphyritic biotite granite in peninsular Malaysia

Nine stages of weathering of a porphyritic biotite granite bedrock material have been distinguished on the basis of differences of colour, texture and the extent of alteration of mineral grains. Determination of the distribution pattern of the different stabes of weathering of bedrock material within the weathering profile then allowed for recognition of six stages of weathering of the bedrock considered on the scale of the mass. Characterisation of the weathering profile over the prophyritic biotite granite bedrock thus involved recognition and definition of weathering of the bedrock, both on the scale of the hand specimen, i.e. as rock material, and on the scale of the mass, i.e. as rock mass.     

Some observations from a field survey of the Irpinia (Italy) earthquake of 23 November 1980

This paper reports a field survey carried out 4 months after the Irpinia earthquake of 23 November 1980. The factors influencing the scale of damage are noted and the correspondence between damage levels and ground motions recorded by the ENEL network of strong motion instruments is briefly discussed.     

Determining the optimum cutting direction in granite quarries through experimental studies: a case study of a granite quarry

Bulletin of Engineering Geology and the Environment - Optimization of cutting operations in quarrying and processing of building stones leads to certain reductions in operational costs. Despite the...     

Thermal cycling effects on the dynamic behavior of granite and microstructural observations

Bulletin of Engineering Geology and the Environment - This study investigated the thermal cycling effects on the dynamic behavior of granite and described its microstructure. The specimens were...     

地球物理测量在广西罗维多金属矿勘查的应用效果

广西罗维多金属矿区出露地层为寒武系小内冲组和黄洞口组,分布多处土壤Ag、Pb、Zn、W、Bi异常,异常具Pb-Ag-Zn、Bi-W、Zn-Bi-W-Pb等组合特征。区内砂泥岩和铅锌矿石样品的磁性无明显差别。经高精度磁测圈出异常3个,反演估算异常磁源体顶面埋深23～43 m或更深;利用EH4大地电磁测深对高磁异常进行查证,以反演电阻率断面图确定低阻和中低阻区的空间分布。经综合“地、化、物”资料后进行钻探工程验证,发现多个银铅锌钨铋多金属矿体,找矿效果甚佳。     

综合物探方法在青海抗得弄舍多金属矿区中的应用

文章通过对青海抗得弄舍矿区航磁异常、布格重力异常的分析,圈定了成矿有利部位,再利用大功率激电和音频大地电磁测深综合物探方法获得不同的物性参数,根据物性参数异常特征之间的相互验证,进行快速找矿,找矿的准确性提高。综合物探方法的应用,避免了单一物探方法的局限性,能获取更多的成矿信息,构建更完善的地质认知,从而取得较好的地质找矿效果。     

A study on pesticide runoff from paddy fields to a river in rural region--1: field survey of pesticide runoff in the Kozakura River, Japan

Runoff characteristics of nine kinds of herbicides from paddy fields were surveyed in the Kozakura River, that is one of the tributaries flowing into the Lake of Kasumigaura, over a period of 23 April to 30 June (before and after rice transplantation) of year. The flow rates of river water and the concentrations of herbicides in the river water were measured every day in May and every 2 days in April and June at six survey sites along the river. The runoff characteristics of herbicides were elucidated by taking account of the rainfall data, the detailed application data (application date and quantities of herbicides applied to each paddy field in a region), and their physico-chemical properties. The runoff rates (the runoff/application amounts ratio) were calculated for each herbicide, resulting in the range of 8.2-22.4%. The runoff rates were correlated fairly well with octanol-water partition coefficient, logP(ow), rather than with water solubility of herbicides.     

A national field survey of house temperatures

Information about temperatures in houses is of importance in assesing the value of various energy conservation measures and gives an indication of the standards of thermal comfort enjoyed by the occupants. In the present paper results are discussed of the most extensive survey of domestic dwelling temperatures to have been taken in the U.K. During February and March 1978, when the outside temperature was close to the average for the heating season, spot measurements of the wet- and dry-bulb temperatures were made in each room of 1000 homes nationwide. On the same occasion, an interview was conducted with an adult member of the household to obtain information on thermal comfort conditions and heating patterns. The globe temperature was measured in the room where the interview took place (usually the living-room). Interviews were conducted both during the daytime and in evenings, and at weekends as well as on weekdays. The mean of the living-room temperatures recorded was 18.3°C, mean kitchen temperature 16.7°C and mean temperature of the warmest bedroom 15.2°C. The average dwelling temperature was 15.8°C. The major sources of variance in temperature were the type and operation of the heating system, the dwelling age, household income, the time of day and geographical location. Household composition was a minor factor. The living-room temperature was relatively insensitive to the above-mentioned factors and had the appearance of being held at a level more or less independent of that in the rest of the dwelling. Centrally-heated houses ran 3°C warmer on average than non-centrally-heated houses. However, the difference in mean temperatures in the living-rooms between the two categories was only 1.5°C dry-bulb and 0.9°C globe temperature. Although strong correlations between a number of the explanatory variables, such as dwelling age and heating system type, means that a deeper analysis is required before a firm causal model can be proposed, the results provide an important new basis for assessing energy conservation options in domestic space heating.     

Integration of geophysical techniques to detect geotechnical hazards: a case study in Mokattam,Cairo, Egypt

Bulletin of Engineering Geology and the Environment - Geotechnical hazards are the main factors that control decisions about construction in structurally complex zones. In the Mokattam area, Cairo,...     

Crack initiation of granite under uniaxial compression tests: A comparison study

In this study, a combination of acoustic emission (AE) method (AEM) and wave transmission method (WTM) is used to investigate the behaviors of AE and ultrasonic properties corresponding to initial fracturing in granitic rocks. The relationships of AE characteristics, frequency spectra, and spatial locations with crack initiation (CI) are studied. The anisotropic ultrasonic characteristics, velocity distributions in different ray paths, wave amplitudes, and spectral characters of transmitted waves are investigated. To identify CI stress, damage initiations characterized by strain-based method (SBM), AEM and WTM are compared. For granite samples, it shows that the ratio of CI stress to peak strength estimated by SBM ranges from 0.4 to 0.55, and 0.49–0.6 by WTM, which are higher than that of AEM (0.38–0.46). The CI stress identified by AEM indicates the onset of microcracking, and the combination of AEM and WTM provides an insight into the detection of rock damage initiation and anisotropy.     

广州地区花岗岩残积土抗剪强度指标取值方法探讨

介绍了研究花岗岩残积土抗剪强度指标取值方法的目的和意义,从室内直剪试验、室内三轴试验、原位直剪试验、平板载荷试验四方面,阐述了花岗岩残积土抗剪强度指标取值的常规方法,并结合其取值方法的研究现状,提出了未来的研究方向。     

Glazing daylight transmittances: a field survey of windows in urban areas

The effect of urban air pollution on glazing daylight transmittance was investigated by measuring the percentage loss in glazing transmittance of a number of windows throughout a large city in the UK. A total of 430 windows in a range of building types and locations were used to create the database for this window survey. The measurements were taken under overcast sky conditions to minimise errors that could occur during periods of rapidly changing sky luminance. In addition, two adjacent photocells were used so that simultaneous comparative measurements were taken. In general it was observed that the loss in transmittance for a vertical window did not usually exceed 10%. The factors that most significantly reduced glazing daylight transmittance were (i) the function/use of the building or the rooms within, (ii) the inclination of the window and (iii) the shading of the window by overhangs. It is, therefore, suggested that future daylight design guidelines should include these factors.     

Geo-environmental characteristics of weathering deterioration of red sandstone relics: a case study in Tongtianyan Grottoes,Southern China

It is reasonable to study the destruction and preservation of stone relics from a geo-environmental point of view. The Tongtianyan Grottoes, known as “the First Grottoes in Southern China”, are located in the city of Ganzhou, Jiangxi province, China, and are the largest cave temples in eastern China and southern China. The grottoes were carved into sandstone palisades during the period from the late Tang Dynasty (755–763 AD) to the Republic of China (1912–1949 AD). In China, the Danxia landform is a special landform characterized by red sandstone cliffs. Different from the grottoes located in arid climate regions, the Tongtianyan Grottoes have the lowest latitude (25°45′N) among all the grottoes in China, and the stone relics are under a perennially warm and humid environment. The monuments have suffered from various forms of weathering deterioration, which can be summarized as five types: exfoliation, bio-weathering deterioration, crack, erosion, and loss. Detailed investigations have been conducted to analyze the mechanisms of the weathering deterioration of the stone relics based on different aspects of geo-environmental characteristics. The weathering sandstone samples were analyzed using X-ray diffraction and X-ray fluorescence, and the chemical weathering indices (LOI, WPI, and WI) were calculated. We found that there is a boundary zone at a depth of 10 ± 2.5 mm from the surface to the inner rock based on the curves of the chemical weathering indices, and the rock outside of the boundary zone has much stronger weathering than that inside.