The primary objectives of the self-boring pressuremeter (SPBM) test are to measure, in situ, the horizontal stress and the stress-strain characteristics of soils and soft rocks. This cylindrical probe tunnels itself into the ground with a minimum disturbance. Conventionally, the advance has been performed using a cutter system housed inside a cutting shoe. Although proven effective, this method is slow and cumbersome. In response to these drawbacks, a jetting insertion method was introduced and designed to allow a faster rate of insertion using a system that is less equipment intensive and easily adapted to conventional drill rigs. To avoid similar potential inconsistencies encountered in earlier SBPM testing with the cutting method, a series of laboratory simulation tests and in situ self-boring pressuremeter tests were carried out in two soft clay deposits to assess the jetting method. The following key insertion parameters were studied: jetting nozzle type, drilling fluid velocity, jetting nozzle position, rate of advance, and jetting flushing system. The results of this study indicate that, as with the cutting method, the jetting method can be used in soft to medium clays to advance the self-boring pressuremeter with minimum disturbance.Resume : Les principaux objectifs de I'essai au pressiombtre autoforeur (PAF) sont de mesurer in situ la contrainte horizontale et les caractCristiques contrainte-dCformation des sols et des roches molles. Cette sonde cylindrique se creuse un tunnel dans le sol avec un minimum de remaniement. Dans la mCthode conventionnelle, l'avance progresse au moyen d'une trousse coupante IocalisCe dans le sabot. Quoiqu'elle ait fait ses preuves, cette mCthode est lente et encombrante. Pour Cviter ces inconvknients, I'on a introduit une mCthode d'insertion B jet consue pour permettre une vitesse d'insertion plus ClevCe et faisant appel B un systbme requCrant moins d'Cquipement et qui est facilement adaptable aux foreuses conventionnelles. Pour Cviter des inconsistances potentielles semblables B celles rencontries dans les essais antCrieurs faits au PAF avec la mCthode de tranche coupante, une sCrie d'essais de simulation en laboratoire et d'essais in situ au pressiombtre autoforeur a CtC rCalisCe dans deux dCp6ts d'argile molle pour Cvaluer la mCthode B jet. Les parambtres clCs d'insertion suivants ont CtC CtudiCs : type d'ajutage du jet, vClocitC du fluide de forage, position de l'ajutage du jet, vitesse d'avancement et systbme d'Cvacuation du fluide du jet. Les rCsultats de cette Ctude indiquent que, comme avec la mCthode B trousse coupante, la mCthode B jet peut Ctre utilisCe d a m les argiles molles B moyennement molles pour faire avancer le pressiombtre autoforeur avec un minimum de remaniement.

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Research presented in this paper was conducted to assess the influence of environmental and physical factors on measurements made with the self-boring pressuremeter (SBPM). It was found that temperature changes during deployment and long-term instrument calibration drift can result in misinterpretation of in situ soil properties. It was also observed that neglecting to consider the sequential order of strain arm lift-off and radial confinement in both membrane calibration and data reduction can have an effect on interpretation of horizontal stresses, particularly in soft clays. Control experiments were conducted to quantify the effect of these factors. Based on the results of these experiments, a method for assessing excess pore pressure at the beginning of a test using the standard Cambridge SBPM transducers was developed. This method incorporates findings from temperature behavior tests. In addition, a modified method of membrane stiffness correction is proposed which includes consideration of sequential order of lift-off and confinement effects.

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Seepage through the karstic limestone foundation below Logan Martin Dam, AL, developed when the reservoir was first filled in 1964, producing springs in the downstream channel, on the riverbanks and eventually at the embankment toe. After a large sinkhole developed on the downstream face of the east embankment on April 9, 1968, the first of many remedial grouting campaigns began, and they continue to this day. This paper reviews the long history of grouting performed at the dam site. There have been many changes and improvements to the means and methods of grouting in recent years that have led to success in mitigating underseepage and improving dam safety. New challenges continue to present themselves. In 2012, exploration conducted at the site revealed that the upper 15 meters (m) of the karst under a rock buttress ("bolster") at the base of the east embankment had about 30 percent voids, raising collapse concerns. In response, a method utilizing discrete grout columns formed using low mobility grout (LMG) was developed, evaluated and then fully implemented. This application of LMG column stabilization is unique and the paper discusses the development and assessment of the method, as well as full implementation of the remediation, including instrumentation and monitoring. Finally, the ongoing work to continue deep curtain high mobility grouting along the axis of the east embankment of the dam is reviewed. The use of real-time grout monitoring, balanced stable grouts, an extensive instrumentation program and the development of a 3D geologic model are guiding the way forward towards assuring dam safety while guaranteeing power generation.