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Abstract Dynamic compaction is a soil improvement technique which involves the repeated application of an impact load to a contact area of the soil surface induced by heavy weights. Experimental measurements were prepared for evaluation of the ground wave propagation induced by the rapid impact compaction. Influence of increase of subsoil stiffness during compaction and terrain configuration were investigated. When the shear strength of soil is exceeded during the penetration of the compaction footing, increase of peak particle velocities is slower but still clearly visible along the measurement line. The peak particle velocity is damped by the subsoil below 5 mm s−1 within 40–50 m from the source of excitation. Attenuation radius is affected by the terrain configuration, when terrain elevations cause the increase of acceleration amplitudes. Rigid bodies in the ground, such as foundation structures, could have similar influence. Dominant frequencies are in the interval from 20 to 40 Hz regardless the distance from the source of excitation or the density of the treated subsoil. Obtained results are preferably related to the given boundary conditions. However, wave propagation pattern and change of its characteristics during densification of the subsoil are applicable at another construction sites considering their particularities.

Dynamic compaction is a soil improvement technique which involves the repeated application of an impact load to a contact area of the soil surface induced by heavy weights. Experimental measurements were prepared for evaluation of the ground wave propagation induced by the rapid impact compaction. Influence of increase of subsoil stiffness during compaction and terrain configuration were investigated. When the shear strength of soil is exceeded during the penetration of the compaction footing, increase of peak particle velocities is slower but still clearly visible along the measurement line. The peak particle velocity is damped by the subsoil below 5 mm s−1 within 40–50 m from the source of excitation. Attenuation radius is affected by the terrain configuration, when terrain elevations cause the increase of acceleration amplitudes. Rigid bodies in the ground, such as foundation structures, could have similar influence. Dominant frequencies are in the interval from 20 to 40 Hz regardless the distance from the source of excitation or the density of the treated subsoil. Obtained results are preferably related to the given boundary conditions. However, wave propagation pattern and change of its characteristics during densification of the subsoil are applicable at another construction sites considering their particularities. [ABSTRACT FROM AUTHOR]

The rapid impact compaction technology is often used in the backfill compaction work for road subgrade, box culvert, and pipeline. There are few cases of compaction treatment for large-scale backfill construction work. At present, there are just a few analyses and researches on its vibration impact in the industry, and there is a lack of similar data and test cases. Taking the main reclamation works of Hong Kong International Airport three runway system project as an example, the construction vibration parameters of the technology were obtained through field tests. Based on the analysis of the tests data, it is concluded that under the condition that the compaction energy is no more than 84 kJ, the construction spacing is no less than 1.25 m, and there is no influence on the conventional monitoring instruments (MPX and GPS), and the safe distance to the temporary buildings is about 15 m. [ABSTRACT FROM AUTHOR]

In February 2015 Cofra Dynamic Compaction (CDC), a heavy Rapid Impact Compaction (RIC) technique to compact granular subsoil, was performed on the Berth 9 Quay Extension project in Felixstowe, UK. The extension consists of a 15.000m2 reclamation between sheet pile walls. The compaction of the reclamation was required to reduce future settlements and improve the properties of the sand behind the quay wall. An extensive compaction trial was performed before the start of the project to assess the compaction procedures and work method in relation to the specifications but also to assess the impact of the compaction on the Quay wall. Compaction effort was monitored during compaction with the use of the crane monitoring system which registers the (induced) settlement with increasing blows. The effect of the compaction has been measured with the use of pre- and post-compaction CPT's. The main quay wall displacements were continuously monitored by a manual station and a robotic total station. During the trial an inclinometer was used to gather more data. The paper focusses on the gathered data, findings and observations during the project and the compaction trials. [ABSTRACT FROM AUTHOR]

Abstract: A possibility of in-situ ground improvement with the Rapid Impact Compaction (RIC) technique was investigated at two test sites where the construction of the high embankments is planned. The location is characterized by up to a 5m thick top layer of loosely deposited silty sands with a medium to very high concentration of coal particles, which strongly influences the in-situ water content. Materials at both test sites were investigated before and after compaction with in-situ measurements (DPSH, LWDCPT, CPTU and DMT) and the laboratory tests on samples taken from the excavation pits. Each test site was divided into four fields, which had the different compaction raster and transferred energies applied to them. It was concluded that for the optimal compaction more than 50% of the field has to be covered with the compaction points. The presence of the coal particles did not affect the results of compaction at the time of the test since the water content was close to the optimum. However, the water content varies seasonally and this could potentially have a strong influence on the levels and uniformity of compaction. The DMT and CPTU tests captured the effect of compaction but since only a few measurements were executed, the results were inconclusive, which was nevertheless surprising. On the other hand, a good correlation was established between the DPSH and LWDCPT tests, which both clearly indicated the difference between different fields and could be used for compaction control. It was also shown that the DPSH test is insensitive for very loose materials (blow count values N 1(60)30SB lower than 3) and in that case the LWDCPT tests should be used instead. [Copyright &y& Elsevier]

Ground improvement has been used on many construction sites to densify granular materials, in other word, to improve soil properties and reduce potential settlement. This work presents a case study of ground improvement using rapid impact compaction (RIC). The research site comprises the construction of workshop and depots as part of railway development project at Batu Gajah-Ipoh, Malaysia. In-situ testing results show that the subsurface soil comprises mainly of sand and silty sand through the investigated depth extended to 10 m. Groundwater is approximately 0.5 m below the ground surface. Evaluation of improvement was based on the results of pre- and post-improvement cone penetration test (CPT). Interpretation software has been used to infer soil properties. Load test was conducted to estimate soil settlement. It is found that the technique succeeds in improving soil properties namely the relative density increases from 45% to 70%, the friction angle of soil is increased by an average of 3°, and the soil settlement is reduced by 50%. The technique succeeds in improving soil properties to approximately 5.0 m in depth depending on soil uniformity with depth. [ABSTRACT FROM AUTHOR]