Model Test Study Of Treatment On Liquefiable Ground Using Crisscross Section Probe Resonant Compaction Method

The foundation liquefaction caused by earthquake often brings huge loss of life and property.So the treatment of liquefiable foundation is an important task.The traditional treatment methods of liquefiable foundation have certain limitations.So it is necessary to propose a more efficient treatment method.The resonant compaction method opens a new road in the field of liquefiable foundation.This paper is funded by the national natural science foundation of China?41372308?,the special funds of basic scientific research funds of central university?sjlxl5₀060?and the scientific research innovation program of postgraduates in Jiangsu province?sjlx15₀060?.In this paper,the resonant compaction method is the research object.The mechanism and effect of the liquefiable foundation strengthened by resonant compaction method and influence of clay partings are the target.This paper adopts the method of model test,supplemented by numerical simulation.The technology of treatment on liquefiable foundation using resonance compaction method is further studied.The main results are as follows:?1?The model test device developed independently consists of four parts,including hoisting equipment,exciting equipment,model trough and measuring system.The soil samples used by the test include sandy silt,fine sand,clay and coral sand.Model test consists of five working conditions.Test scheme of each working condition is generally consistent,including sample preparation,routine test before vibratory test,vibratory test,routine test after vibratory test.?2?The reinforcement mechanism of resonant compaction method mainly includes the following aspects.In the process of vibration,the soil particles move upward in the vibratory hole,forming a vertical drainage channel.In the resonance state,the periodic change of earth pressure and pore water pressure is NV ELEVEN.The earth pressure is larger than the value before vibration.And pore water pressure is less than the value before vibration.The energy transfer law in the resonance state is as follows.Along the transverse direction,the energy transmission is decreasing.And the amplitude of decline is increasing.The energy finally tends to zero.Along the longitudinal direction,the energy transmission of silts foundation is the largest in the lower soil layer,is second in the upper soil layer,is the smallest in the middle soil layer.The energy transmission of sands foundation is the largest in the upper soil layer,is second in the lower soil layer,is the smallest in the middle soil layer.?3?After treatment of resonant compaction method,the foundation has achieved remarkable effects in the following aspects.The relative density of silts foundation increase 19.3%.The relative density of sands foundation increase 35.0%.And the relative density of sands foundation with clay partings increase 30.8%.The settlement of sands foundation is 1.16 times of silts foundation,is 1.38 times of the sands foundation with clay partings.Within 30 cm from the vibratory point,the strength of the soil has been improved.The frequency ratio of silts foundation is 1.003.The frequency ratio of sands foundation is 1.024.The frequency ratio of sands foundation with clay partings is 1.025.All that close to 1.Three kinds of liquefiable foundation have reached the resonance state.The reinforcement effect of sands foundation is better than the silts foundation.?4?The influence of clay partings on the treatment of liquefiable foundation by resonance compaction method includes the following aspects.The drainage channels formed by the vibratory probe were blocked.The velocity and amplitude of moving particles become small.The maximum vibratory acceleration of soil is reduced.And the propagation of vibratory source energy is affected.The compactness of the foundation is decreased by 12%.The settlement is decreased by 27.3%.And the strength is decreased by 50%.?5?The results of numerical simulation with FLAC3D are verified by the model test.In static calculation,the theoretical value of the bottom vertical stress of soil layer and calculated value obtained by FLAC3D are primary phase.It can be considered that the initial stress calculation is reliable.In the different vibratory stage,lower-middle part pore water pressure of soil layer basically follows the following trend.In the transverse direction,the pore water pressure decreases.But the decrease is not large.In the longitudinal direction,pore water pressure increases.And the increase is very large.With the increase of distance from vibratory point,the settlement of soil layer is reduced.The results of numerical simulation are basically consistent with the results of indoor model test.The maximum settlement of numerical simulation is 4cm.The maximum settlement of indoor model test is 4.4cm.