| The development of deep resources and the continuous development of underground space projects such as tunnels and subways have posed new challenges to rock tunneling and hard rock breaking.The traditional drilling and blasting method has complex rock-breaking procedures,poor safety,and low rock-breaking efficiency of tunneling equipment.Based on this,the technique of high pressure foam bursting rock is put forward in this paper.In this paper,the method of combining theoretical analysis,experimental research and simulation research is used to study the rock breaking of high pressure foam bursting device.Based on foam rheological theory and water jet stretching-water wedge theory,build up foam crack rock finite element model,analyzes the bubble column jet impact rock stress distribution and transfer laws of the bottom of the hole,comparing the actual test it is concluded that the bubbles rise to crack of the rock broken form by foam jet impact,seal at the bottom of the bore space up crack force,flowing pressure of foam fluid in rock fracture work together cause the damage of the rock,and through the water jet stretching-water wedge theory explains the bubbles rise to crack the macroscopic breakage of rock failure form a cone-shaped broken pit.Based on the automatic control foam generation and ratio test system,the foam ratio generation test was carried out to analyze the relationship among the physical form,foam characteristics and flow characteristics of the foam,and a dispersive foam suitable for pressure and swelling and cracking was obtained.The effects of foaming agent concentration and air content on foaming efficiency were studied.Based on the test results,the viscosity and stability of foaming fluid were analyzed from three aspects: foam viscosity,half-life and foaming multiple,and the optimal ratio of water,foaming agent and air was obtainedBased on the FEM and fluent simulation,the overall structure of the high-pressure foam expanding and cracking device was designed,and the main structural parameters of the device and the opening characteristics of the hydraulic valve body were studied.The optimal parameters of the foam pressure chamber in the device and the optimal matching Angle between the valve body and the jet nozzle were obtained,and the high-pressure foam expanding and cracking device was processed.Based on high-pressure foam breaking rock test-bed for different rock hardness,hole depth change,secondary crack up under the condition of high pressure parameters,such as foam crack rock test,higher crack with different parameters of rock jie crack surface size,broken,broken,broken blocks of the pit depth quality,the influence of the bubble rise pressure change,get high-pressure bubble up rock cracking device operation the best parameters in the secondary cracks and local network up the formation mechanism of the crack under the homework.Experimental results and the pressure curve of high-pressure bubble rise in bottom sealing model validation,explore the bubbles rise crack rock sealing during the process of distance change on the influence of rock fracture crack extension,it is concluded that high pressure foamed up cracking unit seal from the bottom of the hole distance of 40 ~ 60 mm hole bottom up within the range of the crack effect is good,the rock fracture development accompanied by the surface of the rock damage completely. |
PDF Full Text Request