Experimental And Numerical Study On Static Cracking Technology Of Supporting Beam Of Foundation Pit

To test the efficiency of the static cracking agent on static cracking of supporting beam,expansion experiments were conducted under specific conditions of different water-agent ratios,temperatures.An experiment of static crusher expansion pressure by using strain gauge method,4 steel pipes with different inner diameter were used to measure the expansion pressure,the inner diameter of the steel pipe used is 24 mm,32mm,36 mm,and 39 mm,the wall thickness is 3mm,the length of the steel pipe is 1000 mm.The expansion performance of the static cracking agent is evaluated by the principle of energy release rate.The results showed that the expansion process of static cracking agent could be divided into four phases,the hardening stage of the mixture,the crack propagation stage,rapid volume expansion of the mixture and the slowdown of volume expansion,the agent ratio of 0.28 is the largest with the volume expansion rate of 4.485.The static cracking agent ratio in various water temperatures shows that that the reaction temperature of the water will increase the reaction rate,but cannot alter the volume expansion rate and the maximum temperature the reaction will achieve.During expansion pressures check,the values of the strain gauges at various locations are different,which can be assumed to be triggered by the specific period of applying the crusher slurry,a blowout occurrence occurred on other 4 steel pipes except for smaller steel pipe of 30 mm,resulting in that the agent being sprayed out,the larger steel pipes scale,the simpler it is to spray out which caused the slurry and gas expelled from the pipes which lead to the reaction to be stopped and the steel pipe slowly cooled due to the lower temperature,and the value of the strain gauge eventually lowered to steady.Finally,based on the hole layout of a supporting beam,the displacement and the stress field of concrete are simulated using Abaqus numerical simulation under different hole arrangements with two distinct charges hole.The displacement and stress field appeared around the arranged holes,the maximum tensile stress occurs around the hole with big diameter,the middle hole line presented higher stresses and large tensile stress more than the hole at the edge,the stress at the joint of the two holes is larger,and the stress is larger than the failure strain to produce cracks.