Improving Rigidity of Clay by Using Explosives and Proofing by Multichannel Analysis of Surface Waves (MASW)

Abstract

The construction foundation problem in complex conditions with specific types of soils (peat and organic sediment, sludge, soft clay, etc.) is relevant at the present time. Excessive moisture, low bearing capacity, high compressibility, and other negative qualities of these soils make the process of foundation more expensive and complicated. To improve the properties of granular soil can be applied explosive compaction (EC) technology, which has been used for more than 80 years, but mostly for the compaction of gravels, sands and silts. This paper documents the successful application of EC for the compaction of clay soils. To cause compaction, the sequential detonations were performed using explosives placed in boreholes. To investigate the efficiency of explosive compaction on cohesive clay soil, geophysical testing was performed. Applied geophysical testing methods were a Multichannel analysis of surface waves (MASW) and seismic down-hole, whose test results are shear wave velocities (Vs) in depth. The shear modulus (Go) at small deformation, which is directly related to the Vs, were used to determine the degree of soil improvement. From a comparing of results of pre- and post-blast testing, the positive effects are evident.