随着水利、交通、采矿、房屋建筑、市政建设特别是地下工程的发展,工程结构物的荷载愈来愈大,工作条件愈来愈复杂,深开挖工程愈来愈多,而施工条件却愈来愈受到限制,如采用传统的施工方法,不仅土方工程量大,有时还会遇到很多困难。例如,有的新建或扩建工程由于四周临街或与现有建筑物紧相连接,往往无法放坡开挖;有的工程由于地基比较坚硬难于打桩;也有的工程由于地基比较松软,打桩会影响邻近建筑 With the development of water conservancy, transportation, mining, building construction, and municipal construction, especially underground engineering, the load on engineering structures is getting larger, the working conditions are becoming more and more complicated, and more and more excavation works are being carried out, and the construction conditions are More and more restrictions are being imposed. If traditional methods of construction are used, not only is there a large amount of earthworks, but there are also many difficulties encountered. For example, some new construction or expansion projects may not be able to be sloped and excavated because they are surrounded by streets or connected with existing buildings; some projects are hard to piling because of the foundations; others may be affected by the weak foundations. building