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Application and reliability analysis of DPM system in site investigation of HK weathered granite

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Journal of University of Science and Technol.g. Beijing 2005年第6期12卷 481-488页

作者： Zhuoying Tan Meifeng Cai Zhongqi Yue l.g. tham C.F. lee State Key laboratory of High-Efficient Mining and Safety of Metal Mines （University of Science and Technol.g. Beijing） Ministry of Education Beijing 100083 China Department of Civil Engineering University of Hong Kong Pokfulam Road Hong Kong China

A drilling process monitor （DPM） for ground characterization of weathered granite is presented. The monitor is portable and can be mounted on a hydraulic rotary drilling rig to record various drilling parameters in real time during normal subsurface investigation. The identification method for dominative and subsidiary interfaces has been established. The study reveals that the monitored drilling parameters are dependent on geotechnical materials and can be further applied to characterize ground interfaces. The t-test between manual l.g.ing and DPM l.g.ing has been carried out. The results show that the DPM has high accuracy in interfaces detection and well agreement with the manual l.g.ing. The findings show that the device and data analysis method are of potential application in subsurface drilling exploration in weathered granites. It also seems to have prospective uses in the determination of orebody boundary as well as in the detection of geohazards.

关键词： drilling process monitoring hydraulic rotary drill instrumented borehole drilling geotechnical engineering weathered granite

基于数字图像的非均质岩土工程材料的数值分析方法

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岩土工程学报 2005年第8期27卷 956-964页

作者：陈沙岳中琦谭国焕香港大学土木工程系

提出了一种基于数字图像的非均质岩土工程结构的二维数值分析方法。以花岗岩为例,先将岩石的表面图像导入计算机中;然后采用基于彩色空间的数字图像技术将组成花岗岩的几种主要材料:长石、石英和黑云母一一分辨出来并再现岩石的细观结构... 详细信息

提出了一种基于数字图像的非均质岩土工程结构的二维数值分析方法。以花岗岩为例,先将岩石的表面图像导入计算机中;然后采用基于彩色空间的数字图像技术将组成花岗岩的几种主要材料:长石、石英和黑云母一一分辨出来并再现岩石的细观结构;再通过一个简单的线性转换,将图像细观结构转换为矢量细观结构;最后,岩石的矢量细观结构可以与数值计算方法——有限元法或有限差分法结合,从而实现非均质岩石材料的力学分析。采用有限差分法FlAC程序来分析岩石的破坏过程。传统室内试验数值模拟表明材料的细观结构对应力分布和破坏模式有着明显的影响,基于数字图像的数值分析方法可以真实地实现岩土工程材料的非均质分析。

关键词：岩土材料花岗岩非均质性数字图像处理有限差分法破坏预测

基于岩石可钻性指标的地层界面识别理论与方法

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北京科技大学学报 2006年第9期28卷 803-807页

作者：谭卓英蔡美峰岳中琦谭国焕李焯芬北京科技大学金属矿山高效开采与安全教育部重点实验室北京100083 香港大学土木工程系

岩石可钻性指标是石油、矿山及地质部门广泛用于钻头选择和制定生产定额的重要参数,但现行可钻性指标的定义及参数获取的实验方法还存在许多问题.通过分析,重新定义了岩石的可钻性,提出了以单位能量下的穿孔速率作为可钻性指标的新概念... 详细信息

岩石可钻性指标是石油、矿山及地质部门广泛用于钻头选择和制定生产定额的重要参数,但现行可钻性指标的定义及参数获取的实验方法还存在许多问题.通过分析,重新定义了岩石的可钻性,提出了以单位能量下的穿孔速率作为可钻性指标的新概念;基于钻进过程中有效轴压、转速、穿孔速率和可钻性指标间的耦合关系,建立了可钻性指标的计算公式.同时,对新的可钻性指标在地层识别中的敏感性进行了分析,阐述了可钻性指标在地层识别中的物理意义.研究表明,新的可钻性指标克服了传统可钻性指标在判层中存在的盲区,并可实现沿钻孔剖面的连续判层.

关键词：岩石可钻性地层界面识别钻孔参数耦合关系

A three-dimensional coupled numerical model of nonlinear waves in a harbor

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Science China(Technol.g.cal Sciences) 2008年第12期51卷 2185-2196页

作者： l.g.tham Department of Civil and Structural Engineering The University of Hong Kong

A 3-D time-domain numerical coupled model for nonlinear waves acting on a ship in a harbor has been developed in the present *** whole domain is divided into the inner domain and the outer *** inner domain is the area around the ship,where the flow is expressed by the laplace equation and numerically solved by the finite element *** other area is the outer domain,where the flow is described by the higher-order Boussinesq equations and numerically solved by the finite difference *** matching conditions on the interfaces between the inner domain and the outer domain,the procedure of coupled solution,the length of common domain and the mesh generation in the inner domain are discussed in *** other coupled model with the flow in the inner domain governed by the simplified linear Euler equations and relevant physical experiment are adopted to validate the present coupled model,and it is shown that the numerical results of the present model agree with the experimental data,so the present model can be used for the study on the effect of nonlinear waves acting on a fixed ship in a large area and provide a reference for the time-domain simulation of nonlinear wave forces on an arbitrary object in a large harbor and the 3-D district computation in the future.

关键词： 3-D coupled model nonlinear waves boussinesq equations laplace equation

Characteristic-based operator-splitting finite element method for Navier-Stokes equations

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Science China(Technol.g.cal Sciences) 2011年第8期54卷 2157-2166页

作者： WANg Daguo WANg HaiJiao XIONg JuHua tham l g Research Center for Numerical Tests on Material Failure Dalian University Dalian 116622 China Department of Information Engineering Dalian University Dalian 116622 China Department of Underground Construction and Engineering Tongji University Shanghai 200092 China Department of Civil and Structural Engineering The University of Hong Kong Hong Kong 999077 China

A new finite element method, which is the characteristic-based operator-splitting (CBOS) algorithm, is developed to solve Navier-Stokes (N-S) equations. In each time step, the equations are split into the diffusive part and the convective part by adopting the operator-splitting algorithm. For the diffusive part, the temporal discretization is performed by the backward difference method which yields an implicit scheme and the spatial discretization is performed by the standard galerkin method. The convective part can be discretized using the characteristic galerkin method and solved explicitly. The driven square flow and backward-facing step flow are conducted to validate the model. It is shown that the numerical results agree well with the standard solutions or existing experimental data, and the present model has high accuracy and good stability. It provides a prospective research method for solving N-S equations.

关键词： N-S equations CBOS algorithm finite element method

Instrumented borehole drilling for interface identification in intricate weathered granite ground engineering

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Journal of University of Science and Technol.g. Beijing 2007年第3期14卷 195-199页

作者： Zhuoying Tan Meifeng Cai Z.Q. Yue l.g.tham C.F. lee State Key laboratory for High-Efficient Mining and Safety of Metal Mines （University of Science and Technol.g. Beijing） Ministry of Education Beijing 100083. China Civil and Environmental Engineering School University of Science and Technology Beijing Beijing 100083 China Department of Civil Engineering The University of Hong Kong Hong Kong China

The successful application in drilling for HK simple weathered granite foundation has revealed its further use in instru- mented drilling system as a ground investigation tool in the detection of other lithol.g. formations, geohazards, underground water, and boundary of orebody. To expand the further use and test the accuracy in identification of formation, an R-20 rotary-hydraulic drill rig was instrumented with a digital drilling process monitoring system （DPM） for drilling in an intricate decomposed granite site. In this test ground, the boreholes revealed that the weathered granite alternately changes between moderate and strong. The qualitative and quantitative analysis of the penetrating parameters, indicates the effective thrust force, rotary speed, flushing pressure, penetrating rate, and displacement of the bit fluctuate at ground interfaces. It shows that the parameters get a good response with the change of rock strength at the interfaces, which can reveal the change of the intricate granite formation. Besides, a variable-slope method has been established, for identification of dominative and subsidiary interfaces in the granite site. The result from a t-test shows that the confi- dence of the instrumented drilling system in identification of the geotechnical interfaces is up to 99%.

关键词： drilling process monitoring rotary-hydraulic drilling intricate weathered granite foundation

TIME-DEPENDENT STRENgTH DEgRADATION OF gRANITE

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TIME-DEPENDENT STRENGTH DEGRADATION OF GRANITE

Field testing of irrigation effects on the stability of a cliff edge in loess,North-west China

第二届废物地下处置学术研讨会

作者： l.g.tham Department of Cvil Engineering The University of Hong Kong

Understanding the time-dependent behaviour of the host rock is essential to the safety evaluation of a radioactive waste disposal system.A series of constant loading tests under different confining pressures and temperature with acoustic emission monitoring were performed to study evolution of dilatancy and strength *** location analysis and moment tensor analysis were carried out to reproduce the progressive damage process helping to understand the failure mechanism from microscopic point of view. In this paper,the findings of the study are reproted..

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Field testing of irrigation effects on the stability of a cl...

landslide susceptibility mapping based on Support Vector Machine:A case study on natural slopes of Hong Kong,China

中国科学院地质与地球物理研究所第11届（2011年度）学术年会

作者： l.g.tham Department of Civil Engineering The University of Hong Kong

As it is not uncommon that irrigation has triggered landslides in the Chinese loess Plateau,a full-scale field testing in a typical cracked plateau in Heifangtai,Cansu Province of China to simulate such phenomenon was *** the study,piezometers were installed to measure the groundwater,and crackmeters as well as inclinometers were used to measure the slope *** was pumped from the nearby source daily to simulate the irrigation *** was a sharp increase of pore pressure in the undisturbed loess below the crack when the inclinometer registered considerable movement due to the inflow of water via the *** increase in pore pressure also dissipated ***,the irrigation water dayl.g.ted at the major cracks from the face of the plateau leading to local *** results show that cracks have significant effects on the flow of the irrigation water into the *** rapid rise in the local pore water pressure had reduced the stability of the slope.

关键词： Field testing Irrigation Crack landslide loess plateau

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Landslide susceptibility mapping based on Support Vector Mac...