| In today's world,global climate change has a far-reaching impact on human society.Polar glaciers are an important part of an associated global system.Scientific research and long-term observation of glaciers can not only help people understand the information of paleoclimate and paleogeology,but also help people effectively cope with the severe climate change process and avoid the impact of glacier disasters on human production and life.In the polar regions,the ice core can be obtained through drilling technology to study the internal structure of the ice layer,analyze the paleoclimatic changes or quickly drill holes and put logging equipment in the hole to measure the ice shelf structure,temperature,pressure,ice shelf base slip speed Data and shooting images,so as to better carry out research and monitoring of the material circulation process at the bottom of the ice shelf.At present,the commonly used rapid ice drilling methods are electric auger,steel drill,hot melt drill and hot water drill.Among them,hot water drilling technology is a rapid drilling method that uses high-speed hot water jets from the nozzles to impact and melt ice(snow)layers.It is of great significance for the study of polar ice glacier glaciology.The hot water drill uses the ice and snow meltwater of the glacier to drill without the use of drilling fluid,thus effectively solving the environmental pollution problem caused by the use of drilling fluid.As the ice drilling method with the highest drilling speed,hot water drilling is widely used in the observation of the freezing and thawing process of the ice shelf,sampling of ice deposits,physical structure of ice layer,temperature measurement,ice creep research,ice.Measurement of the underlying base slip velocity,acquisition of the ice lake connection channel,capture of cosmic neutrinos,and some other scientific purposes.However,hot water drilling technology needs to remove the residual hot water from the main winch hose immediately after drilling stops.Otherwise,the hot water in the hose will be slowly cooled and frozen under the action of Antarctic low temperature environment,and the frost heave force generated during the freezing process will easily cause the hose rupture.Therefore,the development of efficient and reliable water removal method and system for main pipeline is one of the key technologies to ensure the successful implementation of hot water drilling.This paper summarizes the research significance and current situation of hot water drilling technology at home and abroad,introduces in detail the most widely used ice drilling method in Alpine glacier and polar ice layer drilling,hot water drilling,and draws lessons from foreign hot water drilling experience,combines the characteristics of hot water drilling,designs a new hot water drilling and dewatering system,determines the dewatering system.The specific method of dewatering operation is carried out and the test is carried out.The water removal system includes three parts:power device,retractable device and antifreeze device.According to hydrodynamics,the loss of water flow in hose of hot water drilling winch is calculated theoretically.The length,inner diameter,bending radius and flow velocity of hose are determined preliminarily.The loss along the hose is proportional to the length of hose,the flow velocity of water body,and is inversely proportional to the diameter and bending radius of hose,that is,the length of hose and the bending radius of water body are inversely proportional.The longer the hose length is,the larger the flow velocity of water body is,the smaller the diameter of hose is,the smaller the bending radius is,and the greater the loss along the hose is.The loss along the hose is calculated when different flow of water body flows through the hose,and the minimum pressure required by the air compressor of the power plant of the dewatering system is determined to be about 0.79MPa.Therefore,two kinds of air compressors,0.8 MPa,1 m~3 and 3 MPa and 1 m~3,are selected for testing.The indoor and outdoor tests were carried out by comparing two different methods of using air pressure to transport high-pressure air as power and gravity of water body of rotating winch as thrust.The following conclusions were drawn:(1)When high-pressure air is used alone to deliver high-pressure air,although high-pressure air can push some water out,there is still a lot of water remaining in the hose.This is because the hose is spirally wound around the winch.After the water body is discharged,some of the remaining water body still accumulates at the bottom of the hose.When the high-pressure air pushes the water body accumulated in the one-piece hose to move upward,the gravity increases as the water body increases,and the gravity increases.When the gravity is greater than the thrust generated by the high-pressure air,part of the water body falls back,creating a gap,causing part of the high-pressure air to advance to the next section of the hose,and the water body in the original hose is gradually reduced until the water volume cannot form a water column filled with the hose,and finally a water column is reciprocated up and down in the water hose under the action of high pressure air and gravity,so that the water removal is not complete enough;(2)When the winch is used alone to remove water,its dewatering effect is poor,and only a small amount of water can be discharged.Increasing/smaller winch speed significantly helps the dewatering operation,so this method is not suitable for large-scale hot water drilling system.(3)The hot water drilling and dewatering operation is carried out by the combination of the high pressure air delivered by the air compressor and the rotating winch.This is because the water body moves under the thrust of the high pressure air,and the force generated is greater than that of the hose and the water body.The friction between the frictional force and the return of the water body causes the water body not to climb when the hose rotates,and then the water body's own gravity does not hinder the water body from advancing,so that the water can be completely removed,and the preliminary water removal operation only needs to be 1.2.The total water removal time was 2.7 hours.(4)After the initial water removal operation is completed,pumping the antifreeze into the winch hose can effectively prevent the accidental damage caused by the freezing of the residual water droplets,protect the drill and hose,and determine whether the water body is discharged.After the experimental study was performed on the dewatering system of hot water drill in Antarctic ice shelf,it is found that the new dewatering method proposed in this paper has the advantages of simple operation,strong practicability,high speed,high efficiency and more environmental protection,and can meet the requirements of Antarctic field. |
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