Experimental study on soluble salt of dredger fill in Central Fishing Harbor of Tianjin

Taking the soil of Central Fishing Harbor of Tianjin undrained and drained by vaculty as an example, we made detail analysis on draining condition of soil,element and distribution of soluble salt in this Harbor area and scratched its influence on IP ,pH and engineering property of soil． The authors found out that the soluble salt content of the undrained was higher than of the drained,and the contents of Na + and Cl － in both nearly take up 50% respectly． The content of other soluble salt was very low,and along with the deepening of sampling,the content variety regulation was nearly the same among Na + ,Cl － and the total contents of soluble salt． To the same kind of cohesive soil,IP is different for various contents of soluble salt in the soil． The relationship between IP and soluble salt contents were nearly the same for the drained and the undrained,but the variety range of IP in the undrained was much larger．     

Compaction of coal wash to optimise its utilisation as water-front reclamation fill

The coal mining industry in and around Wollongong, New South Wales, Australia, is responsible for producing an ever growing quantity of coal washery reject materials and other mine waste aggregates. Considerable effort is being undertaken to reuse, beneficially, these waste products in the immediate suburbs of Wollongong. In this paper, detailed laboratory investigations carried out on coal wash (i.e. coarse coal washery reject), produced at Dendrobium coal mine near Wollongong, are presented. Geotechnical tests were conducted to determine the particle size distribution, compaction characteristics, shear resistance and collapse potential. Compaction tests were performed under dry and submerged conditions to examine comprehensively the compactability and the strength properties of coal wash. The laboratory tests show that, if properly compacted, Dendrobium coal wash has a good potential as effective low-porosity fill for embankments and port reclamation.     

Evolution of an incised valley coastal plain estuary under low sediment supply: a ‘give‐up’ estuary

The literature on incised river valley sedimentology is dominated by studies of sediment‐rich systems in which the valley has been filled during and/or shortly after drowning. In contrast, the Holocene evolution of the Kosi Lagoon, South Africa (an incised coastal plain river valley) took place under very low sedimentation rates which have produced a distinctive stratigraphy and contemporary sedimentary environments. The findings are based on a synthesis of the results of studies of seismic stratigraphy, sediment distribution, morphodynamics and geomorphology. Barrier migration was prevented by a high pre‐Holocene dune barrier against which Holocene coastal deposits accumulated in an aggradational sequence. Holocene evolution of the back barrier involved: (i) drowning of the incised valley; (ii) wave‐induced modification of the back‐barrier shoreline leading to segmentation during the highstand; and (iii) marine sedimentation adjacent to the tidal inlet. Segmentation has divided the estuary into a series of geochemically and sedimentologically distinctive basins connected by channels in the estuarine barriers. The seismic stratigraphy of the back barrier essentially lacks a transgressive systems tract, shoreline modification and deposition having been accomplished during the highstand. The lack of historical geomorphological change suggests that the system has achieved morphological equilibrium with ambient energy conditions and low sediment supply. This study presents a classification for estuarine incised valley fills based on the balance between sea‐level rise and sedimentation in which Kosi represents a ‘give‐up’ estuary where much of the relict incised channel form is drowned and preserved. It exhibits a fundamentally different set of evolutionary processes and stratigraphic sequences to those of the better known incised valley systems in which sedimentation either keeps pace with sea‐level (‘keep‐up’ estuaries) or occurs after initial drowning (‘catch‐up’ estuaries).     

昆明新机场高填方地基沉降的二维数值模拟

昆明新机场地处岩溶发育地区,工程地质条件复杂,地基沉降问题突出.结合工程地质勘察资料,分析机场T1区地基沉降问题.结合实际地质模型建立该区跑道计算模型,分析该区跑道填方地基的沉降规律.实际监测数据表明,根据数值模拟结果进行的施工达到很好的效果.     

长短桩技术在有邻近堆土建筑中的应用

建筑物周边的不均匀堆土给建筑物带来了安全隐患,如何消除这些安全隐患又避免高昂的桩基工程造价,就这一问题针对土层中存在多层可利用的桩端持力层提出了短桩、桩间土提供承载力,堆土侧采用长桩控制建筑物的不均匀沉降的长短桩组合桩基础的设计思路,并对全短桩方案和邻近堆土侧加长桩长的长短桩方案分别进行了三维有限元分析。分析结果表明,对有邻近不均匀堆土的建筑物采用长短桩组合桩基础,不仅可以有效地控制建筑物的不均匀沉降,而且大大减小了桩基础的工程造价,对解决不均匀堆土对建筑物带来的危害,提供了一种设计思路。     

Efficiency of local minima and GLM techniques in sinkhole extraction from a LiDAR-based terrain model

ABSTRACT

The aim of this paper was to study reliable automated delineation possibilities of karst sinkholes using a LiDAR-based digital terrain model (DTM) with pixel-based classifications. We applied two approaches to extract sinkholes: (1) general linear modeling (GLM) with morphometric indices derived from DTM; (2) and a local minima-based delineation using only LiDAR DTM as the input layer. The outcome of the local minima was significantly different from the reference ones but found all the sinkholes without previous knowledge of the area. The GLM-based outcome did not differ statistically from the reference. Results showed that these approaches were ef?cient in detecting sinkholes based on LIDAR derivatives, and can be used for risk assessment and hazard preparedness in karst areas: GLM had an overall accuracy of 89.5% and local minima had an accuracy of 92.3%; both methods identified sinkholes but also had commission errors, identifying depressions as sinkholes.     

Nucleus properties of Comet 67P/Churyumov-Gerasimenko estimated from non-gravitational force modeling

By considering model comet nuclei with a wide range of sizes, prolate ellipsoidal shapes, spin axis orientations, and surface activity patterns, constraints have been placed on the nucleus properties of the primary Rosetta target, Comet 67P/Churyumov-Gerasimenko. This is done by requiring that the model bodies simultaneously reproduce the empirical nucleus rotational lightcurve, the water production rate as function of time, and non-gravitational changes (per apparition) of the orbital period (ΔP), longitude of perihelion (Δ?), and longitude of the ascending node (ΔΩ). Two different thermophysical models are used in order to calculate the water production rate and non-gravitational force vector due to nucleus outgassing of the model objects. By requiring that the nominal water production rate measurements are reproduced as well as possible, we find that the semi-major axis of the nucleus is close to 2.5 km, the nucleus axis ratio is approximately 1.4, while the spin axis argument is either 60°±15° or 240°±15°. The spin axis obliquity can only be preliminarily constrained, indicating retrograde rotation for the first argument value, and prograde rotation for the second suggested spin axis argument. A nucleus bulk density in the range 100-370 kg m⁻³ is found for the nominal ΔP, while an upper limit of 500 kg m⁻³ can be placed if the uncertainty in ΔP is considered. Both considered thermophysical models yield the same spin axis, size, shape, and density estimates. Alternatively, if calculated water production rates within an envelope around the measured data are considered, it is no longer possible to constrain the size, shape, and spin axis orientation of the nucleus, but an upper limit on the nucleus bulk density of 600 kg m⁻³ is suggested.     

The Chandra X-ray Observatory: An Astronomical Facility Available to the World

The Chandra X-ray observatory, one of NASA’s “Great Observatories,” provides high angular and spectral resolution X-ray data which is freely available to all. In this review I describe the instruments on Chandra along with their current calibration, as well as the Chandra proposal system, the freely-available Chandra analysis software package CIAO, and the Chandra archive. As Chandra is in its 6th year of operation, the archive already contains calibrated observations of a large range of X-ray sources. The Chandra X-ray Center is committed to assisting astronomers from any country who wish to use data from the archive or propose for observations.     

区间值直观模糊集的直积与相关性

在区间值直观模糊集上定义新的算子,给出这些关系与算子之间的一些重要性质,并讨论了区间值直观模糊集的相关性问题.