在美国,顶板锚杆支护虽然普遍应用,但是仍然有一些难题长期未得到解决。最初,顶板锚杆都很简单,制造厂家将锚固力和张力不同组合开发出专用的顶板锚杆,而且工作状况良好。这么多年来这些产品不断改进并投放市场,但是指导支护实践的理论没有改变。 In the United States, although roof bolting is commonly used, there are still some problems that have not been solved for a long time. Initially, roof bolts are simple, manufacturers have developed a combination of anchoring force and tension special roof bolt, and work in good condition. These products have been continuously improved and put on the market for so many years, but the theory that guides the practice of support has not changed.