A new transient method for determining soil hydraulic conductivity function

Instantaneous profile method (IPM) is a transient method for measuring a soil hydraulic conductivity function (SHCF), which relates soil hydraulic conductivity with suction. In the existing interpretation method of the IPM, boundary flux during testing must be known to integrate instantaneous profiles of water content for obtaining water flow rate. However, it is usually difficult and expensive to measure a boundary flux and if not known, assumptions that may not be easily justified (especially in the field condition) have to be made. In this study, a new method is proposed so that any boundary flux needs not to be measured, controlled or assumed during a test. The new method is evaluated through (i) hypothetical column tests using transient seepage analyses and (ii) five case studies. The new method is capable of determining a SHCF with good accuracy. Normalised root-mean-square deviation (NRMSD) for the old and new methods is less than 5% and 10%, respectively. The accuracy of the new method can be increased substantially (i.e., NRMSDThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Investigation of plant growth and transpiration-induced matric suction under mixed grass-tree conditions

Although evapotranspiration-induced matric suction for single species has been widely studied, little is known about how mixed-species planting would affect the plant growth and induced matric suction. This study aims to explore the effects of grass-tree interaction on their growth and induced matric suction during evapotranspiration (ET) and rainfalls. Field monitoring was carried out to measure matric suction responses in compacted soil that was vegetated with (i) single tree species, Schefflera heptaphylla and (ii) mixed species of the trees and a grass species, Cynodon dactylon. In each condition, three tree spacings (120, 180 and 240 mm) were planted. When tree spacing increased from 120 to 240 mm, the peak tree root area index (RAI, for fine roots with diameterThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

An evaluation of soil-structure interaction associated with a multi-propped excavation

SIGLEAvailable from British Library Document Supply Centre- DSC:DX173986 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Inherent anisotropic stiffness of decomposed tuff and alluvium

Recent advances in laboratory testing techniques enable accurate measurement of shear wave velocity in different planes for the determination of stiffness anisotropy of soils at very small strains. While most studies of elastic stiffness anisotropy have been conducted on sedimentary soils and clean sands, relatively little investigation into the anisotropic stiffness of decomposed materials has been reported. In this paper, a recent study of the degree of inherent stiffness anisotropy of natural completely decomposed tuff (CDT) and natural alluvium sampled from an excavation site in Hong Kong is discussed and reported. The shear moduli of CDT and alluvium at very small strains in the vertical and horizontal planes were determined by shear wave velocity measurements across specimen height and diameter using bender elements. The results are compared to the degree of inherent stiffness anisotropy of different materials. The effect of soil structure of natural material on stiffness anisotropy is highlighted

E-government integration with web services and alerts: A case study on an emergency route advisory system in Hong Kong

Quick and efficient response to emergency is important for every city. This depends on the quality of the dispatch of emergency service to the scene and back to hospital or other governmental offices. To provide the path of the shortest traveling time is a difficult task, especially if there is traffic jam near the scene. In this paper, we formulate a conceptual model for the transport network and Emergency Route Advisory System (ERAS) implementation architecture handle the emergency response. The ERAS requires information integration from various governmental departments and public services through Web services, such as maintaining the databases of transportation information and traffic condition. Making use of such information, a challenge is to find a time-efficient or cost-effective path intelligently. Our ERAS interacts with the call centers of emergency service departments (such as the police, fire services, and ambulances) through alert mechanisms to integrate emergency processes. Through this complex case study, we demonstrate the effectiveness of the use of Web services and alerts in e-Government information and process integration. © 2006 IEEE