Measurement And Analysis Of The Dynamic Response Of Less Cohesive Soil Under Impact Load

Under impact loads, such as slump body of blasting, less cohesive soil prone to liquefying, damaging the building or other ground facilities. When the impact load is constant, less cohesive soil clay content has a great impact on liquefaction. As the blasting engineering of cities has become more and more common, it is necessary to do some research on the liquefaction of less cohesive soil under impact loadsIn this paper, taking Nanjing Shuiximen viaduct Blasting Engineering for example, the mechanism of less cohesive soil liquefaction and discriminating methods have been researched. Based on the use of drilling, laboratory test, standard penetration test, on site testing in blasting field and other means, testing a series of survey of rock and soil was carried out. Identified field region can be liquefied less cohesive physical and mechanical characteristics of the field region hydrogeological and engineering geological conditions and the conditions of Nanjing regional geological conditions made a note, and in the scene of the blast less cohesive soils under impact load the dynamic response were tested. Through the analysis of field data, the following conclusions was concluded:1. Verify blasting TOUCHDOWN vibration frequencies between 2-1 OHz, closer to the natural frequency of the building, touching the ground shaking lasts longer than the duration of blasting vibration.2. The test value of acceleration in this area less cohesive soil 0.15g. The test value of pore pressure ratio is less than 0.4, the value of the test pore pressure coefficient is 0.88.3. This test verifies less cohesive soil clay content on liquefaction behavior has an important influence. Under the same conditions than the less clay content less cohesive soil more susceptible to liquefaction. Less viscous clay content in its liquefaction resistance is not monotonically increasing relationship, but there is one of the most dangerous content, about 10% or so.4. Under impact loads, when the soil drainage conditions are similar, as the depth increasing, the soil pore pressure dissipation super speed. Deep soil layers in the negative pore pressure.5. The blast impact deformation mainly in the fill and silt soil, filling is compressed, silty soil produce small deformation, less cohesive soil layer hardly distorts.6. Recommended in the future high-rise buildings Demolition works, especially when less cohesive soil which can be liquefied layer shallow depth, you can use the touch is located around the building to be demolished to dig drainage wells to reduce impact loads caused by liquefaction of foundation soil risk.