My country’s current full-rotation casing drilling rig has not achieved independent research and development.In the 1990s,my country introduced a full set of pipe equipment from Japan,which is mainly used in railway construction and bridge engineering.In the background,the outer ring is high in price,the Qinghai-Tibet railway and the subway project.It has been applied in construction.In 2004,Shanghai Tunnel Company introduced two full-rotation casing drilling rigs from Japan,and used them for engineering repair in the collapse of Line 4,and achieved good results.They are the successful rescue of large-scale accidents in my country by applying full set of pipe equipment.example.

　　1.Construction methods and main features of full-pipe full-rotation drilling rig

　　(1)Casing rotation mode and vertical loading mode

　　Under normal circumstances,the casing rotation method is divided into two methods:full-rotation drill rotary drive casing and pipe-handling machine small-angle rubbing casing.The method of pressing and pulling the casing while rotating can promote casing extraction and pressure.The resistance is significantly reduced.Practical experience in engineering construction shows that the resistance of the simultaneous pulling and pressing of the casing in the full-rotation mode and the tube rolling mode is about one-fifth or one-third of the static pressure mode.In general,vertical loading methods are mainly divided into two types:dynamic pressure and static pressure.Dynamic pressure mainly includes high-frequency vibration,ground-frequency vibration,and impact[2].Applying dynamic pressure on a suitable formation can improve the efficiency of static drilling.For example,the application of vibrating casing on coarse-grained formations with less water content and soil layers can promote a significant reduction in friction between the formation and the casing,thereby promoting Increased casing penetration speed.The application of the water-bearing fine sand layer can liquefy the sand layer,causing the casing to be unable to be poured into the formation.Therefore,in this case,the static pressure method of rubbing pipe is more suitable.

　　(2)Auxiliary rock crushing method in open space and slag discharge method in casing

　　In order to further reduce the frictional resistance between the bottom layer and the casing,and to promote the effective increase of the casing drilling speed,the high-pressure water pipe can be pre-buried inside the double-wall casing.This method is used to form a high-pressure water jet at the bottom of the casing.Thus,the efficiency of casing drilling in sand,soil and weathered rock formations is significantly improved.In addition,the application of the full set of pipe hole bottom drive method in hard rock formations can significantly improve the efficiency of the full set of pipes.For example,the use of large-wind DTH hammers for advanced rock exploration and drilling can effectively solve the emergency construction of special projects.This equipment requires great The air volume air compressor is the main research direction in the future.Under normal circumstances,the slag discharge method in the casing mainly includes two methods of supporting the rotary excavator for soil extraction and the crane's flushing and grabbing of soil.Rotary excavation of the supporting rotary excavator is called the complete pipe rotary excavation method.A rotary drilling rig must be added to extract soil from the casing.The drilling efficiency is significantly improved,the one-time purchase cost is higher,and the bottom and piles are cleared.The hole quality is good and has a higher comprehensive construction benefit[3].Crane punching and grabbing soil is called a full set of pipe punching and grabbing hole construction method.The equipment is not only practical but also relatively simple.The crawler crane hoisting and grabbing the soil in the casing can also be used in pouring concrete and lifting steel cages.The overall construction cost of the overall project is low for the hoisting and placement of machinery and tools on the construction site.This method has been widely used in many projects in my country.

　　(3)Analysis of basic characteristics

　　First,the hole-forming feature.Mud-free,dry-type undisturbed soil extraction,drilling into the casing wall protection all the way.Second,the perfusion characteristics.Fill the whole casing to protect the wall,while pulling the casing and pouring down.Again,the application area.Full-casing pull-out pile,full-pipe occlusal pile,full-pipe cast-in-place pile,and full-pipe wrecker Finally,environmental protection advantages.Basically applicable in all complex stratums,it will not disturb the surrounding foundations,the pile quality is good,and the dry hole formation is an environmentally friendly new technology for large diameter hole formation.

　　2.Discussion on construction technology of full-pipe full-rotation drilling rig

　　(1)Drilling a full set of pipes into holes

　　First of all,the full-rotation rig presses the casing against the rotary drive casing and the middle pile position of the rig at the same time,so that the casing can be drilled into the formation quickly.Secondly,when the casing is drilled into the formation,the release of the grab bucket can be carried out along the inner wall of the casing through the step-down application until the bottom of the hole is punched to grab the soil,and the casing is drilled while grabbing the soil in the casing.When encountering underground obstacles or boulders,the casing shoe edge can hold down the boulders while cutting[5].Finally,a hammer is used to impact and crush the boulder in the casing.The boulder can be quickly crushed.During the continuous drilling of the casing,the boulder outside the casing will be squeezed into the wall of the broken hole,and then grabbed Scoop out the broken boulders in the casing.According to this method of punching and grasping while drilling into the casing,until the casing is drilled to the designed pile depth,and after all the rock and soil in the casing are grasped,the final hole of the bottom sediment is cleaned.

　　(2)A full set of pipes are poured into piles

　　First,after the hole is finished,the hoist is lowered into the filling pipe and steel cage,and the casing is pulled out while the concrete is poured.Second,after the concrete is poured,all the casings are pulled out and the pile is completed.And compared with the percussion reverse circulation construction method,the mud circulation rotation construction method and the rotary excavation construction method and other bored pile construction methods,the full rotation casing punching and grabbing bored pile construction technology has its own significant advantages.First of all,there is no risk of hole wall collapse during the pouring,drilling,and wall protection of full-bore casing during engineering construction,and the bored pile does not have the risk of shrinking or breaking the pile.Secondly,the pile has high vertical accuracy,it will not disturb the foundation of surrounding buildings when it is piled,there is no vibration,noise,no mud discharge,and it will not interfere with surrounding residents,and it is very suitable for almost all complex formations.Finally,it is more suitable in many fields such as pulling out underground prefabricated piles and filling piles,occluding piles for deep foundation pit support,removing underground palm obstacles,and replacing old piles with filling piles.Compared with other construction methods,this construction technology has the characteristics of application innovation to a large extent,and it is a new type of brick hole cast-in-place pile construction technology that is green and environmentally friendly,broad-spectrum and efficient in urban infrastructure construction in my country.

　　(3)Complete set of pipes to remove deeply buried steel piles and steel pipes

　　First,the construction process.The full-rotation large-diameter casing sleeves the underground small-diameter steel piles or steel pipes,and the internal soil is taken out with a punching bucket;the untouched soil around the steel piles is removed by water jet spraying;the steel piles are used for crane Pull it out directly.Second,the scope of application.The small diameter steel structure in deep underground where the casing cannot be grabbed,hammered,cut,and broken.Under normal circumstances,it can be removed from steel piles or steel pipes with a diameter in the range of 800-1000mm,and the applied outer tube diameter is in the range of 1500mm to 2000mm,and the buried depth is usually in the range of 20 to 40 meters.The cleared space between the steel pipe and the outer casing is mainly used for hydraulic jet treatment and soil extraction with a grab bucket,which has high effectiveness and environmental protection.Because the outer casing is full-hole wall protection,it will not affect the foundations and foundations of surrounding buildings during the construction process.It has no vibration and noise.It is very suitable for in-situ clearing and urban reconstruction.

　　Conclusion

　　To sum up,the article mainly discusses and discusses the construction methods and main features of the full-pipe full-rotation rig and the construction technology of the full-tube full-rotation rig.The purpose is to promote my country's related fields to strengthen the The in-depth research and full application of the project can effectively improve the efficiency and quality of engineering construction,so as to obtain greater economic benefits.