The CSM cell and the Goodman Jack are two borehole devices which can be used for determining in situ modulus. The paper presents laboratory and field experience obtained using the devices. Data reduction procedures are described. Advantages and limitations are discussed. The CSIR "Doorstopper" is a borehole device widely used for determining absolute stress. Discussion has been continuing regarding the proper data reduction procedures. The paper describes some new procedures for data analysis.
La cellule de C.S.M. et le Verin Goodman sont deux dispositifs de me sure de compressions en paroi de forage. Ce memoire traite de tarage des resultats de laboratoire et de terrain obtenus à l'aide de ces deux dispositifs ci-haut mentionnes. Les procedes de reduction des donnees sont decrits. Leur avantages et restrictions sont aussi presentes. La cale CSIR "Doorstoper" est un dispositif de paroi de forage communement employe pour determiner la contrainte absolue. La procedure appropriee de reduction des donnees a ete largement discute dans le memoire et des nouvelles methodes d'analyse des donnees ont ete exposees.
Die CSM Zelle und der Goodman Hebel sind zwei Borlochgerate, welche fuer due Bestimmung des in-situ Modul benuetzt werden können. Mit her Anwendung von diesen Geraten wurden in diesem Berichte die erhaltenen Laboratorischen und Feld Erfahrungen beschrieben. Weiterhin wird der Data verminderungs Verlauf beschrieben. Vorteile und Einschrankungen werden erötered. Fuer die Bestimmung der unbedingten Spannung wird meistens der CSIR Tuerhalter benuetzt. Die Eröterungen wegen dem genauem Data verminderungs Verlauf sind fortlaufend. Etliche neue Verfahren fuer die Data Analyse wurden in diesem Berichte beschrieben.
During recent years, considerable emphasis has been placed upon the development of computational techniques (finite element, etc.) for analyzing rock mass/structure interaction. Good success has been realized. The development of the tools and techniques for providing the required input data has unfortunately not kept pace. Of the devices constructed for use by various investigators, few have been developed to the point of commercialization. The main reason for this is that although the interest has been present there has been little money available for the development and comprehensive testing of such tools/techniques. Undoubtedly this is the result of a small potential market, the relatively high associated costs, and a high risk of failure. The potential for high costs to a construction project which can be directly attributable to poor site evaluation has received little consideration. Many of the devices/techniques which have reached the marketplace, have not, for many reasons, been evaluated under a full range of operating conditions prior to their introduction. It remains for the users to develop applications and sometimes procedures for data collection and interpretation. This paper describes (1) the use of the CSM cell, for obtaining the modulus of rigidity of the rock surrounding a borehole, (2) data reduction procedures for the Goodman Jack, and (3) data reduction procedures for the CSIR "Doorstopper Gage". The first device is presently in the prototype stage. The latter two devices are commercially available and have in the past been the subject of much discussion.
The CSM cell (7) was developed over the period 1970–72 for determining the modulus of rigidity of the rock surrounding a 38 mm diameter borehole. If the Poisson's ratio for the rock is known or can be estimated, then the modulus of elasticity can be calculated. The CSM cell system is shown diagramatically in Figure 1. Basically it consists of an inflatable membrane (the CSM cell) which is attached to a pressurization system. An adiprene membrane is used to transmit the fluid pressure to the wall of the borehole. The seal design is similar in principle to that used by Hoek and Franklin (5) in the development of their triaxial cell. It has worked effectively at pressures up to 10,000 psi. A screw type of pressure generator connected to the cell by high pressure tubing allows monitoring of the change in system volume as a function of the applied pressure. By a calibration procedure, the change in borehole volume can be separated from the total volume change. Using the borehole volume-pressure curve and equations developed from elasticity theory, one can calculate the rigidity modulus. In this section, the procedure for using the cell will be described, applications discussed, and results presented.
Prior to testing, the stiffness (pressure/ volume relationship) of the CSM cell system (Ms) must be determined. This is done by obtaining the pressure/volume relationship (M) when the cell is inserted in a calibration cylinder of known dimension and elastic properties. Such a calibration curve is shown in Figure 2. Some advantages of the CSM cell system over similar previous devices are (1) the adiprene membranes used to apply pressure to the borehole wall are very tough and resilient.
