改进喷头提高混凝土质量干式喷射混凝土的干料与水混合只限于喷头的水环至受喷面之间，出于距离短和混合时间少，容易造成回弹量大和出现干斑等现象，既浪费材料，也影响混凝土强度，对支护带来一定困难。自从湿式喷射机研制成功，给喷射混凝土带来很多好处，但干式喷射混... Improve the nozzle to improve the quality of the concrete The dry material of the dry shotcrete is mixed with water. It is limited to the water ring of the sprinkler and between the sprayed surface. Because the distance is short and the mixing time is short, the rebound volume is large and dry spots are likely to occur. The waste of materials also affects the strength of the concrete and brings certain difficulties to the support. Since the successful development of wet jets, it has brought many benefits to shotcrete, but dry jet mixing...