ABSTRACT

By using the borehole elastic modulus test and sound wave inspection for typical representative spots of a dam foundation, the deformation behavior parameters of grouted weak rock of workplace foundation are obtained, and the potential relationship between wave velocity VP and elastic modulus E is derived. Then the quality of the rock is evaluated by the wave velocity. Comparative analysis shows that the consolidation grouting is better for the rock with poor engineering property under the natural condition, but for the rock with good mechanics strength characteristic, the improved effort is not very good. However, two test indicators are all satisfied with the analytical requirement. Therefore, this method is effective for grouting quality detection of rock.

1 INTRODUCTION

Elastic wave which is using in field dynamic tests is generated with pulse source. The acoustic parameters of Elastic wave propagation in rock mass will be changed, just likely wave velocity, vibration amplitude, frequency spectrum and so on, which is influenced by geological body such as lithology, structure, weathering degree, etc. The geological structure and physical and mechanical property of rock mass will be directly reflected by these changes, therefore, all kinds of physical and mechanical parameters using in constructing can be obtained by field dynamic test.

Elastic wave which is using in field dynamic tests is generated with pulse source. The acoustic parameters of Elastic wave propagation in rock mass will be changed, just likely wave velocity, vibration amplitude, frequency spectrum and so on, which is influenced by geological body such as lithology, structure, weathering degree, etc. The geological structure and physical and mechanical property of rock m ass will be directly reflected by these changes, therefore, all kinds of physical and mechanical parameters using in constructing can be obtained by field dynamic test. (Wang, 2003)

The foundation rock character is mainly argillaceous dolomite, breccia dolomite, marlite and mud stone of T1yn4 after excavating the workplace foundation of Guangzhao Hydropower Station of Beipanjiang River. The rock airslakes seriously and cracks are more developing. The karst is more developing in the contact zone between argillaceous dolomite and medium bedded limestone of T1yn3–2, and the P1 compress-crushed zone still goes through the middle of the factory. After the 40m excavation depth, on the surface it is mainly weathered rock, and there still is heavy weathered rock partly. The groundwater is active. The argillaceous dolomite that weathered seriously and breccia dolomite can fast emolliate and disintegrate when they contact the water. So the engineering nature is very bad and cannot satisfy the designing requirement. Soft rock mass of workplace effect of soft rock mass is inspected and evaluated by using the method for field dynamic test according to the corresponding relation between the acoustic wave of rock and deformation modulus, which is satisfied designing requirement.

2 THE PRINCIPLE FOR THE SONIC WAVE TESTING TECHNIQUE

There are two kinds of in-situ test methods for rock strength, one is in-situ static load test and the other one is in-situ dynamic test.

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