Patent EP-3690144-A1 (EP)
Title: Method for compacting bases laid using weak mineral soils
Inventor: TER-MARTIROSYAN ZAVEN GRIGOR'EVICH
IPC: E02D27/26
Filed: 2017-12-08
Abstract: The invention relates to construction, in particular to methods for strengthening soils under bases and foundations of buildings and structures, including electric power industry facilities.The technical result achieved by this invention consists in compaction of the base composed of weak mineral soils by determining the optimal design process parameters of the ground piles over the entire area of the base.The essence of the invention is that the method of compaction of bases composed of weak mineral soils that includes formation of a well, filling each well with the compacting material, and creation of a compacting effect on the compacting material by the hollow tubular working tool to form a ground pile, proposes to perform preliminary engineering and geological surveys of the base area and determine the values of the modulus of deformation, the Poisson's ratio, the internal friction angle, the specific cohesion, the specific gravity, the initial void ratio of the weak mineral soil, set the required design modulus of deformation of the layer to be compacted, then, taking the value ε<sub>i</sub>of expansion deformation of each well equal to 0.1, calculate the void ratio of the weak mineral soil after compaction around the ground pile and determine the predicted value of the liquidity index of the weak mineral soil at each step, then, according to the known normative values, take the nearest preliminary value of the modulus of deformation of the mineral soil surrounding the ground pile, depending on the obtained values of the void ratio of the weak mineral soil after compaction around the ground pile ei and the soil liquidity index after compaction, then take the spacing of the ground piles equal to three diameters of the hollow tubular working tool and determine the value of the actual average reduced modulus of deformation of the base, compare it with the design modulus of deformation of the mineral soil and, in the case of obtaining a smaller actual average reduced modulus of deformation of the base soil than the design one, increase the well expansion deformation value iteratively in increments of 0.1 and repeat the calculation of the actual average reduced modulus of deformation of the base until the design value is reached or spacing of the ground piles is equal to the value of 1.5 times of the diameter of the hollow tubular working tool, and calculate the increase of the well radius corresponding to the value of the accepted expansion deformation during piling; the length of the ground pile is taken equal to the distance from the roof to the sole of at least one layer requiring compaction, then drill the well corresponding to the ground pile length by insertion of a hollow tubular working tool, feeding the compacting material into the well through a cavity of a hollow tubular working tool; the compacting effect for formation of a ground pile is carried out by insertion of a hollow tubular working tool into the compacting material; then, perform additional engineering and geological surveys on the area of the base to determine the modulus of deformation of the compacted mineral soil between the ground piles; calculate the actual average reduced modulus of deformation of the compacted base and compare it with the design value; and if the actual average reduced modulus of deformation of the base does not correspond to the design value, install additional ground piles between previously installed ones.