A Knowledge-based System for the Estimation of Geotechnical Properties

Antonis Giolas, PhD Thesis, University of Durham, 1995

ABSTRACT

Ground properties are mainly evaluated from direct measurements obtained from either laboratory or field tests. As an alternative, or in conjunction with test measurements, ground properties can also be estimated from correlations and published summaries of "typical" values. The advantages of their use are that both are simple, easy to use and they provide a cheap, if crude, means for the rapid estimation of ground properties.

A knowledge-based system has been developed to provide a tool for storing and using correlations and "typical" values for the estimation of ground properties. The system was implemented in the ProKappa software, running under X windows on a Sun Spark 2 workstation. The system developed is intended to provide geotechnical engineers with a decision-support tool and to demonstrate the applicability of knowledge-based system technology to the ground property evaluation problem.

The development of this system involved the identification and collection of the domain knowledge (knowledge associated with the ground, ground properties, "typical" values and correlations, which was elicited from the relevant technical literature). Generic forms for the representation of correlations and "typical" values in the system were developed (which provide a consistent form for the representation).

The system also incorporates an inference engine, which includes the process that makes use of this knowledge to produce estimations for ground properties; a user interface to facilitate the use of the system; and finally knowledge acquisition modules for updating of existing knowledge, to ensure that the system will maintain its functionality in the future.

CHAPTER 1 INTRODUCTION 1

1.1 General. 1

1.2 Overview of the thesis 3

CHAPTER 2 THE APPLICATION OF KNOWLEDGE-BASED SYSTEMS TO THE ESTIMATION OF GROUND PROPERTIES. 6

2.1 Introduction. 6

2.2 KBS components. 8

2.3 Development stages of KBS. 9

2.4 KBS in Geotechnical Engineering. 15

2.5 Discussion. 20

2.6 Conclusions. 22

CHAPTER 3 DEVELOPMENT TOOLS. 23

3.1 Introduction. 23

3.2 The ProKappa software. 23

3.2.1 Objects, slots, facets and applications. 24

3.2.2 Programming languages. 27

3.2.3 User interface development tools. 31

3.2.4 Monitors and Active Relations. 34

3.3.5 Summary. 38

CHAPTER 4 REPRESENTING THE GROUND AND ITS PROPERTIES. 39

4.1 Introduction. 39

4.2 A model for representing the ground. 41

4.2.1 Rocks. 42

4.2.2 Soils. 46

4.3 A model for representing ground parameters. 49

4.4 Implementation in the system. 54

4.5 The representation of "typical" values. 56

4.6 User interface facilities. 62

4.7 A knowledge acquisition module for typical values. 69

4.8 Summary. 78

CHAPTER 5 REPRESENTING CORRELATIONS IN A STRUCTURED FORM. 81

5.1 Introduction 81

5.2 Representing correlations in a structured form 85

5.2.1. Variables 85

5.2.2. The estimation procedure 88

5.2.3. Applicability 88

5.2.4. Reliability 90

5.2.5. Comments 92

5.3 Implementation in the system 92

5.3.1 The Correlation application 93

Introduction 93

Variable slots 95

Parameter slots 97

Data_Check! slot 100

The Estimation Procedure 104

Applicability Slots 105

Reliability 106

5.3.2 The Correction module 106

5.3.3 The CorrUI module 107

5.4 Summary 119

CHAPTER 6 A KNOWLEDGE ACQUISITION MODULE FOR THE IMPLEMENTATION OF CORRELATIONS. 123

6.1 Introduction 123

6.2 Establishment of the basic parameter 124

6.3 Variables and parameters 129

6.4 Implementation of estimation procedures. 140

6.5 Applicability definition. 145

6.6 Reliability definition. 151

6.7 Comments. 152

6.8 Updating correlations. 152

6.9 Overview of the Update module. 154

CHAPTER 7 DISCUSSION - FUTURE DEVELOPMENT 156

7.1 Discussion. 156

7.1 Future development. 162

CHAPTER 8 CONCLUSIONS 165

REFERENCES 167

Appendix A Correlations and Corrections A-1

Part 1: Correlations. A-1

Part 2: Corrections A-38

References A-43

Appendix B Typical values for ground properties B-1

Appendix C The ProTalk Code C-1


PhD Theses in Geo-Engineering