Variable Rate Cone Penetration Testing in Hydraulically Placed Fly Ash Deposits.pdf

Andrew Fuggle, WSP USA, Inc.
Longde Jin, WSP USA, Inc.
Mark Taylor, WSP USA, Inc.

Description

Variable Rate Cone Penetration Testing in Hydraulically Placed Fly Ash Deposits Authors Mr. Andrew Fuggle - United States - WSP USA, Inc. Mr. Longde Jin - United States - WSP USA, Inc. Mr. Mark Taylor - United States - WSP USA, Inc. Abstract Cone Penetration Testing (CPT) is widely used for in-situ characterization of hydraulically placed man-made materials, such as mine tailings and fly ash. These materials are not typical natural soils and are often silt-sized and in a very loose state. Standard methods of interpreting CPT tests developed from either clays or sands are generally inadequate for these materials. Studies have found that at a standard penetration speed of 2 cm/s, the dynamic pore pressure response in these man-made materials often indicates partial drainage conditions near the cone. Studies on the effect of partial drainage on estimating drained and undrained shear strengths are very limited. Laboratory research remains difficult due to the challenges in undisturbed sampling and replicating in-situ conditions in the laboratory. This paper presents variable-rate CPT field tests in a hydraulically placed fly ash deposit within an inactive ash basin. Three CPTs were performed with different penetration speeds: one pushed at a fast rate (6 cm/s), one at a slow rate (0.2 cm/s), and one at standard penetration speed (2 cm/s). Soil behavior classification is compared using the interpretation of different rate CPTs and laboratory index testing. Effects on drained and undrained shear strengths are discussed and results are compared to laboratory triaxial shear compression tests. Effects on flow liquefaction screening are also addressed.

 
May 16th, 8:00 AM May 16th, 8:30 AM

Variable Rate Cone Penetration Testing in Hydraulically Placed Fly Ash Deposits.pdf

Grand Rapids, Michigan

Variable Rate Cone Penetration Testing in Hydraulically Placed Fly Ash Deposits Authors Mr. Andrew Fuggle - United States - WSP USA, Inc. Mr. Longde Jin - United States - WSP USA, Inc. Mr. Mark Taylor - United States - WSP USA, Inc. Abstract Cone Penetration Testing (CPT) is widely used for in-situ characterization of hydraulically placed man-made materials, such as mine tailings and fly ash. These materials are not typical natural soils and are often silt-sized and in a very loose state. Standard methods of interpreting CPT tests developed from either clays or sands are generally inadequate for these materials. Studies have found that at a standard penetration speed of 2 cm/s, the dynamic pore pressure response in these man-made materials often indicates partial drainage conditions near the cone. Studies on the effect of partial drainage on estimating drained and undrained shear strengths are very limited. Laboratory research remains difficult due to the challenges in undisturbed sampling and replicating in-situ conditions in the laboratory. This paper presents variable-rate CPT field tests in a hydraulically placed fly ash deposit within an inactive ash basin. Three CPTs were performed with different penetration speeds: one pushed at a fast rate (6 cm/s), one at a slow rate (0.2 cm/s), and one at standard penetration speed (2 cm/s). Soil behavior classification is compared using the interpretation of different rate CPTs and laboratory index testing. Effects on drained and undrained shear strengths are discussed and results are compared to laboratory triaxial shear compression tests. Effects on flow liquefaction screening are also addressed.