| With the rapid expansion of China’s infrastructure construction,groove rock excavation blasting technology which is an important part of modern blasting engineering,has been widely used in the foundation excavation of city construction,like,light rail,highway,subway tunnel,oil and gas pipelines,water supply and drainage pipeline and cable trench.The so-called trench refers to the excavation of a narrower width and a certain length of grooves from the natural plane.Therefore,the free surface of groove blasting is less,the value is important,easy to accumulate water in the lower position,the blasting effect is relatively poor and the blasting damage(mainly blasting slungshot,vibration)of surface blasting is generally more difficult to control.Especially in the complex and changeable rock mass conditions,these problems are more obvious.At present,in order to meet the needs of actual production,researchers at home and abroad have introduced big hole blasting technology into the groove blasting construction and achieved remarkable results.But in the specific condition of layered rock mass,there still do not have a complete set of blasting parameters can ensure the quality,schedule,safety factor.Aiming at this problem,this paper studies the application of large diameter groove blasting technology in stratified rock mass by means of finite element analysis software ANSYS/LS-DYNA and field test,trying to find out a set of groove blasting excavation technology which is suitable for layered rock mass.The specific work done and the results are obtained as follows:(1)The inclined hole is introduced into the large diameter groove blasting technology,and the angle of the slot is the only variable.A finite element model is established to investigate the rock damage condition under the condition of 70 degrees,75 degrees,80 degrees and 85 degrees.Through observing the stress cloud map and the relationship between stress and time of the rocks around the cutting hole,it is concluded that the blasting effect is the best when the inclination angle of the slot hole is 75 degrees,it not only for provides sufficient empty cavities for the auxiliary hole,but also does not affect the function of the auxiliary hole.(2)By using the finite element analysis software ANSYS/LS-DYNA to establish the model of layered rock mass with horizontal cracks and combined with the field test,the large aperture pre splitting blasting technology were studied by the hole diameter of 90 mm and 115 mm.Three evaluation indexes of pre crack gap,half hole rate and unevenness are used as discriminant basis.The results show that when the diameter of the hole is 115 mm,there is no obvious damage to the rock in the layered fracture,and the structure surface of the preformed wall is more complete,and there is no obvious bump.(3)The large diameter groove blasting technology has been applied in the light rail line project of S1 in the underground section of the core area of Gui’An New District,and the blasting effect is very good.It not only ensures the construction progress,but also saves the construction cost,and has certain guiding significance for similar projects. |
