ABSTRACT:

In the present study the penetration of grout in a rock joint is simulated using Computation Fluid Dynamics (CFD) and the two-phase finite volume numerical method. Also the fluid flow is considered as a transient flow. The grout is simulated as a real Bingham fluid using Herschel-Bulkley model. Applying saw-cut joints, various joint matedness and different tooth numbers in a specific joint length and changing the tooth height, the effect aperture variation and relative roughness are investigated. The results indicate that the penetration length is under the influence of fluid viscosity, joint aperture, grouting pressure and the grout yield stress. With increasing fluid viscosity, the penetration length decreases and the grouting time increases. The grout yield stress variations resulting more effect on the grout penetration length rather than the viscosity changes. Moreover the results indicate that the joint section was not completely filled by grout and in this simulation the penetration progress in the joint is cleanly illustrated. Decreasing of the joint matedness causes low grout penetration length. Decreasing the tooth height and the tooth numbers in a specific length leads in to low roughness of rock joint.

1. INTRODUCTION

Grouting is a set of operations which in the course of it the grout is injected into the medium discontinuities under pressure. The main object of grouting is stated to be improvement of civil and mining working environments such as improvement of medium elasticity modulus, preventing ground settlement (reinforcement grouting) and etc. Furthermore, we can decrease medium permeability applying grouting to fill discontinuities, which is one application of constructing the grout curtain for dams. [1, 2] One of the paramount influential parameters during the grouting operation is to predict the grout penetration length. The grout penetration length is a function of the grout characteristics, medium specifications and the grouting technical execution limits. Several researchers have carried out majority of studies to predict the grout penetration length in a single rock joint. They mostly consider some presumptions to simplify the grouting operation. The obtained results mainly indicate direct influence of the grout pressure and the rock joint aperture but inverse effect of grout yield stress on the penetration length. [1] In the most of previous studies [3-6], the joint aperture is considered constant or to simulate aperture variations, joint is divided into sections with constant non-equal apertures which consequently yields instantaneous aperture changes and ignores abrupt pressure fall in aperture change spot. Also Bingham fluid behavior model is used to simulate the grout having two components namely yield stress ( 0 t ) and viscosity (ยต) but practically the viscosity parameter is ignored to compute the grout penetration length. Furthermore, the grout flow is presumed as a steady state flow and then after satisfying stopping conditions the pressure distribution through the grout length is studied though the grout flow nature in the rock joint is completely transient. In the present study firstly a summary of previous studies on the field of grouting in the rock joints is presented.

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