Dynamic compaction

Abstract: Introduction. Site investigation. Soil classification. Soil types. Exclusion techniques. Sheet piles. Contiguous bored piles and secant piles. Slurry trenches. Diaphragm walls. The character of bentonite slurry. Compressed air. Ground freezing. Introduction. Methods of ground freezing. Hydrogeology and the nature of frozen soils. Strength and behaviour of frozen ground. Drainage techniques. Filter drains. Drainage of slopes. Sand drains, sandwicks and band drains. Lime columns. Groundwater lowering. Sumps. Wellpoint systems. Ejector or educator systems. Bored wells. Settlement and groundwater abstraction. Electro-osmosis and electrochemical stabilization. Compaction and consolidation techniques. Mechanical compaction of soil. Precompression. Compaction piles. Vibrocompaction. Dynamic compaction. Explosive compaction. Soil reinforcement and soil anchors. Reinforced earth. In-situ reinforcement techniques. Soil anchors. Geosynthetic materials. Types of geosynthetic materials. Properties of geosynthetic materials. Functions of geosynthetics. Uses of geosynthetics materials. Grouts and grouting. Introduction. Properties of grouts. Penetration of grouts. Types of grout. Grouting. Soil stabilization. Cement stabilization. Lime stabilization. Other materials used for soil stabilization. Thermal stabiliziation. Appendix. References. Further reading. Index.

Abstract: Field measurements from over 120 sites have been collected to study current practice and determine if similarities exist in the response of the ground to site improvement by dynamic compaction. Data were obtained from published reports and files. Ground conditions at these sites were quite diverse, including natural sands, hydraulic fills, rubble, clay fills, and miscellaneous materials. General trends are presented which show that crater depths, ground vibrations, and the depth of influence increase with the energy per blow. The magnitude of induced subsidence, static cone resistance, standard penetration resistance, pressuremeter modulus, and limit pressure tend to increase with the applied energy per unit area.

Abstract: Compacted soils wetted under load can both swell and collapse (subside) depending on their condition and the magnitude of the vertical overburden stress. One‐dimensional compression tests were conducted to clarify the influences of compaction method, compaction water content, relative compaction, vertical stress level, and load‐wetting sequence on post‐compaction wetting‐induced volume changes in a moderately plastic clayey sand. Compaction method and load‐wet sequence had only a minor effect on wetting‐induced collapse. The double‐odometer test was judged to be sufficiently accurate for use in evaluating wetting‐induced collapse. Both swelling and collapse were reduced or eliminated by compacting the soil at water contents on the wet side of the line of optimums for impact compaction. Collapse, but not swelling, could also be reduced by compacting the soil to high levels of relative compaction. By plotting isograms of volume changes in the compaction water content‐relative compaction space, combinations ...

Abstract: The state-of-practice for performing remedial ground densification and evaluating earthquake liquefaction potential of loose saturated sands have evolved relatively independent of each other. This is in spite of the fact that the induction of liquefaction is typically requisite for remedial ground densification of sands. Simple calculations are presented herein for estimating the mechanical energy required to densify a unit volume of clean, loose sand using deep dynamic compaction, vibro-compaction, and explosive compaction. These computer energies are compared with that required to induce liquefaction during an earthquake using the Green-Mitchell energy based liquefaction evaluation procedure. The comparison highlights the importance of the efficiency of the method in which the energy is imparted to the soil and the importance of the mode of dissipation of the imparted energy (e.g., possible modes of energy dissipation/expenditure include: breaking down of initial soil structure, ramming soil particles into denser packing, and radiating away from the treatment zone). Additionally, the comparison lays the preliminary groundwork for incorporating the vast knowledge base gained from fundamental studies on earthquake induced liquefaction into the design procedures of remedial ground densification techniques.