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**Industry**

**Oilfield Places**

**Technology**

Youliang, Zhang (Chinese Academy of Science) | Xiating, Feng (Institute of Rock and Soil Mechanics, Chinese Academy of Science) | Chengxiang, Yang (Institute of Rock and Soil Mechanics, Chinese Academy of Science) | Shaojun, Li (Institute of Rock and Soil Mechanics, Chinese Academy of Science)

Currently the scale of geotechnical projects, such as Three Gorges Projects, the excavation of large underground openings in Qingjiang Shuibuya Water Power Plant, becomes larger and larger, the structures and geological environments met in the projects are more and more complicated and the requirements for computing precision and time become higher and higher. Due to the restrictions of the speed and storage capacity of single PC, the simulations of large projects are generally performed under many simplifications, with few considerations of the complicated structures and small geological tectonics. Besides, info construction is a new branch of geotechnical engineering. Info construction is to readjust the original design based on the rock and soil parameters which are obtained by back analysis using the data monitored during the construction. The adjusted designs should be finished before the next construction step. Consequently to implement these computations with high precision and in real reasonable short time is a new challenge to geotechnical engineering. Even though specialized supercomputer has large memory and high speed, it may be difficult for a single supercomputer to solve such super large problems as global weather simulation either. Furthermore it is not convenient for most of geotechnical engineers to access supercomputers. On the other hand, the speed of PC processors and performance of Windows NT have been improved rapidly in recent years. All these factors enable a cluster of PCs connected by LAN to be an ideal substitute of SGI/Cray T3E or IBM SP2. Clusters of PCs have many advantages, such as much lower cost higher scalability and flexibility, over supercomputers. ' Presently little concern on parallel computing is shown and few literatures can be referred to in geotechnical engineering. The current paper proposes parallel computing methods to solve large-scale problems in geotechnical engineering. Parallel computing solves large-scale problems by making use of the CPU and memory of many single personal computers, so it reduces greatly the computing time and increases the scale of computing problems. The applications of some parallel computing methods in geotechnical engineering are described. These methods include parallel domain decomposition finite element method, parallel finite difference method parallel boundary element method and parallel genetic programming, etc .. Then the features and implement of parallel platform on Windows NT are presented. As an example, results of slope stability evaluation by parallel genetic programming are reported.

ISRM-ARMS2-2001-081

ISRM International Symposium - 2nd Asian Rock Mechanics Symposium

SPE Disciplines: Management and Information > Information Management and Systems > Artificial intelligence (0.98)

ISRM-ARMS2-2001-142

ISRM International Symposium - 2nd Asian Rock Mechanics Symposium

application, classification, condition, correlation, data mining, discontinuity, formation evaluation, machine learning, parameter, quality, relationship, reserve classification, RMR, rock, rock class, rock mass, rock mass classification, rock mass classification method, RQD, seismic modeling, system, value, velocity, well logging

SPE Disciplines:

- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Reserves Evaluation > Reserves classification (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)

1) Domino effect of loading rate on quantitative analysis of strength

2) Domino effect of loading rate on quantitative analysis of modulus.

3) No quantitative description of the rule between creep life and creep stress. Recently, with the fast developing of nonlinear theories and damage mechanics, they were being applied in the studies of rock engineering. Kachanov first( 1958)advanced the damage conception in 1958 while studying the creep rupture process of the metal. In 1976, Dragon and Mroz constituted a continuum damage model based on the concept of fracture area. In the sequel, many scientists such as Krajcinovic( 1981), Kachanov(1982), Costin(1983), applied damage mechanics to study the damage properties of rocks from different view or points. At present, several representative damage theories were suggested and applied:

I) The conception of effective modulus was put forward to define the damage variable. Commonly, the unloading modulus was thought as the effective modulus of damage. But there are many disputed opinions on this conception.

2) The conception of effective areas was suggested to define the damage variable of rock masses. Fracture mechanics must be applied in this method.

3) Desai model. Desai thought that the rock could be divided into two parts: damaged and undamaged .The property of rock depended on the joint action of the two parts.4) Micro-damage theory. In this theory, the influence of the distribution of micro-cracks was considered.

1) The shape of complete stress-strain curves of rocks under tensile loading is similar to the shape of the curves under compression loading.

2) The law of loading rate dependence of the tension strength is similar to that of the compressive strength.

ISRM-ARMS2-2001-058

ISRM International Symposium - 2nd Asian Rock Mechanics Symposium

Li, L. (Rock Engineering Research Center, Department of Civil Engineering, The University of Hong Kong) | Tham, L. (Rock Engineering Research Center, Department of Civil Engineering, The University of Hong Kong) | Tsui, Y. (Rock Engineering Research Center, Department of Civil Engineering, The University of Hong Kong) | Lee, P.K. (Rock Engineering Research Center, Department of Civil Engineering, The University of Hong Kong)

ISRM-ARMS2-2001-067

ISRM International Symposium - 2nd Asian Rock Mechanics Symposium

Chung, So-Keul (Korea Institute of Geology, Mining & Materials) | Synn, Joong-Ho (Korea Institute of Geology, Mining & Materials) | Park, Chulwhan (Korea Institute of Geology, Mining & Materials) | Park, Chan (Korea Institute of Geology, Mining & Materials) | Choi, Sung-Oong (Korea Institute of Geology, Mining & Materials)

The lining of a water pressure tunnel has a role in the increase of mechanical stability, the prevention of rock fall at tunnel crown, the suppression of hydraulic jacking and ground water leakage, and the improvement of water now by reducing the frictional resistance between water and tunnel wall. On the contrary to these advantages, additional cost for lining must be increased. In design of lining and un lining, therefore, various aspects should be considered such as tunnel stability, efficiency of water now, and the purpose and maintenance of tunnel. Many water pressure tunnels in Norway have been constructed without lining(Broch 1985, 1988, Selmer-Olsen 1985). This is mainly based on two aspects. One is that the rock condition in Scandinavia peninsula is very hard. The other is the basic concept of support design that some small rock fall is allowable as far as this does not influence on the tunnel stability, head loss of water pressure and maintenance of water flow channel, of course, there are some cases of collapse of unlined tunnels. In construction of water pressure tunnel recently in Korea, the lining is basically included in the support design after the experience of rock fall accident of an unlined water tunnel a few years ago. The water tunnel to be considered here is also designed as lining for the whole tunnel length at the initial design Stage. However, rock is found out very fresh and hard during actual excavation and so the initial lining design turned to be re- considered. for the re-design of lining and un lining pattern of this water pressure tunnel, the detailed estimations of rock mechanical and hydrological factors are carried out and the guideline of the lining design is established. The field investigation and laboratory test for the rock mass classification, the numerical analysis using UDEC and UNWEDGE code for the estimation of mechanical stability, and hydrological analysis for the estimation of the water now efficiency are carried out. The basic design criteria are evaluated.

ISRM-ARMS2-2001-121

ISRM International Symposium - 2nd Asian Rock Mechanics Symposium

The Numerical Manifold Method (NMM) is a flexible method to solve the problem containing continuum and discontinuum. The meshes of this new method are finite covers : the mathematical covers define only the rough approximations. The real material boundary or the physical mesh defines the integration fields. Using the finite cover systems, continuous, jointed or blocky materials can be computed in a mathematically consistent manner. The difficulty in practical application is to choose the cover functions and weight functions. A simple and efficient way is the use of finite element covers. That is to say, the finite element meshes can be used to define finite covers. In these covers, the weight functions are the shape functions of FEM. Shi (1996) has given details on the triangular finite element Covers, Shyu and Salami ( I995)have considered quadrilateral isoparametric element covers in NMM. As we all know, in FEM , the quadrilateral Q4 isoparametric element is more efficient than triangular element. For bending problem and 3- D problem, the precision and efficiency of the Q4 element is not sufficient. Wilson has suggested to use non-conforming isoparametric element in FEM (Wang & Shao. 1995). In NMM, the research work of this element has not been done but it may be important in real application. In this paper, the use of Wilson non-conforming elements In NMM is discussed and the details of the matrices of equilibrium equations are also given for program coding. An example of cantilever beam is used to verify the precision of the Wilson isoparametric element in NMM.

The choice of suitable cover functions is very important for successful use of NMM. The FEM isoparametric element is often used in NMM because of its convenience. This paper discussed the application of Wilson non-conforming element in NMM and the matrices of the equilibrium equations are derived. A problem of cantilever beam is studied in this paper. Compared with classical Q4 isoparametric element.

ISRM-ARMS2-2001-087

ISRM International Symposium - 2nd Asian Rock Mechanics Symposium

Moosavi, M. (Mining Engineering Department, Faculty of Engineering. The Univeraity of Tehran) | Khosravi, A. (Mining Engineering Department, Faculty of Engineering. The Univeraity of Tehran) | Jafari, A. (Mining Engineering Department, Faculty of Engineering. The Univeraity of Tehran)

Bond may be defined simply as the gripping effect of an annulus (usually concrete or cement) with an embedded length of a steel bar (smooth or deformed) to resist forces tending to slide the bar longitudinally. There are contradictory ideas about whether the bond is a property of annulus or of the bar. However, there is no doubt that the properties of both (for the annulus, compressive strength and confinement and for the bar.

ISRM-ARMS2-2001-052

ISRM International Symposium - 2nd Asian Rock Mechanics Symposium

bar, bolt, Bond, bond capacity, bond failure, Bond Failure Mechanism, cell, dilation, displacement, Figure, mechanism, pressure, radial, result, rock, sample, study, test

SPE Disciplines:

Classical fracture mechanics defines three basic modes of fracture, i.e. Mode I (opening), Mode 11 (sliding) and Mode III (tearing), from the loading point of view (Irwin, 1957). It is assumed that fracture extends in pre-existing crack plane. That is true for most metal materials. For rock materials, however, pure shear loading applied on a pre-existing crack is not certain to result in a Mode II fracture. Numerical calculations show under pure shear loading, both tensile and shear stresses exist at the crack tip and they have the same order of magnitude (Rao, 1999). Since tensile strength of rock is known to be much smaller than its shear strength, Mode I fracture easily occurs before Mode Il frcture. Suggested method for determining Mode I fracture toughness of rock,

Blanket grouting is conducted beneath the impervious zone of embankment dams to control the seepage through the shallow part of the rock foundation. The rectangular pattern is generally used as the layout of blanket grouting holes in Japan, and the grouting is done according to the split-spacing method. In this layout, primary holes are first drilled at the same intervals, and secondary holes are drilled diagonally between them. This halving sequence continues until the permeability of the sequence decreases sufficiently. These sequences are divided into two: one group of sequences is called the sequence of design holes where all holes are drilled at the same interval in each sequence, and the other is called the sequence of additional holes where such holes are only drilled in locations that are below the required standard in imperviousness. To execute blanket grouting effectively, it is necessary to widely and precisely measure the permeability of the dam foundation before and during blanket grouting, because a main flow path is caused not only by the local high-permeability but also by the spatial distribution of the permeability. In Japan, the effect of blanket grouting is now evaluated based on the sequential order of 15% exceedence probabilities (hereafter, it is expressed as '15% exceedence probability value') in permeability in the designed area at each sequence. But this statistic cannot be considered as the representative value in the dam foundation when additional holes are constructed locally. In the split-spacing method, there are some advantages in that the locations of additional holes are chosen easily, but there are also some disadvantages: the evaluation of the improvement in the imperviousness by blanket grouting is retarded and the number of additional holes increases in a geometrical ratio with the progress of the sequences. We should tackle these problems to respond to the recent social demand for the reduction of the cost of dam construction, so it is necessary to examine more rational methods of evaluating grouting effects. We had already carried out two-dimensional seepage analyses using a simple model in order to clarify the relationship between the spatial distribution of unimproved elements and the location of a main flow path (Satoh et al 1999a, I999b) using the percolation theory (Odagaki 1997).

A number of approaches have been suggested for the stability analysis of soil slope by Fellinius (1939), Taylor (1948), Bishop (1955), Janbu (1954), Greenwood (1983), Mongenstern and Price (1965), Spencer (1967) etc. Similarly, the stability of a rock slope can be investigated by a number of methods such as plane failure analysis. Wedge Method of analysis etc. Thus when the slope consists either of soil or of a rock mass, those method can be readily applied. However, in the case of natural slope, one hardly finds a slope consisting of a single material. Such slopes are usually made of soil and rock masses together and analysis of stability of such slopes calls for a special approach. So far very little work has been done in this direction. Authors have suggested a method of analysis applicable to such natural slopes consisting of soil with an overburden of rock mass. A computer program has also been developed for quicker analysis and solution of the problem. The formulation of the approach was necessitated by a study of failure of an actual hill slope in Guwahati, a city which has witnessed an unprecedented pace of urbanization of-late with indiscriminate use of hill slope for building activities. This has resulted in many devastating landslides with repeated loss of life and properties. It is felt that whenever conditions are similar with increasing pressure on land necessitating use of hill slopes, such approach would have special practical relevance and urgency. Investigation carried out on twenty four landslide areas of the city has revealed that landslide become specially devastating when failure occurred in slope of soil with overburden of rock masses. The multiple landslides that occurred at Kacharibasti of Guwahati constitute a typical example of this kind. A sketch of pre-failure stage of the slope is given in the fig-I. In the situation represented by Fig-1, a question of interest is whether the failure of the composite slope is triggered by the rotational failure of the top rock mass caused possibly by rain softened weak underlying soil or is triggered by failure of soil portion bellow.