Classifications

• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
  • E02D19/00—Keeping dry foundation sites or other areas in the ground
  • E02D19/06—Restraining of underground water
  • E02D19/12—Restraining of underground water by damming or interrupting the passage of underground water
  • E02D19/14—Restraining of underground water by damming or interrupting the passage of underground water by freezing the soil
• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
  • E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
  • E02D3/11—Improving or preserving soil or rock, e.g. preserving permafrost soil by thermal, electrical or electro-chemical means
  • E02D3/115—Improving or preserving soil or rock, e.g. preserving permafrost soil by thermal, electrical or electro-chemical means by freezing
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH DRILLING; MINING
  • E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B36/00—Heating, cooling, insulating arrangements for boreholes or wells, e.g. for use in permafrost zones
  • E21B36/001—Cooling arrangements
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH DRILLING; MINING
  • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
  • E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
  • E21D9/001—Improving soil or rock, e.g. by freezing; Injections

Definitions

• the invention relates to a device for freezing soil, with a closed at its one end face with a freezing tube bottom freezing tube, in the interior of which a above the freezing tube bottom ending inner tube is arranged.
• the invention further relates to a method for carrying out civil engineering work.
• Such devices which are also referred to as “freezing lances", are used in particular in civil engineering work, such as in shaft, mine, tunnel or tunnel construction to protect personnel and equipment against earth and water ingress.
• Such a device is for example in the DE 3112291A1 described.
• the soil within a delimited area by thermal contact with a refrigerant is cooled so much that the water contained in the ground freezes around the frozen lances used and the soil is thereby solidified and stabilized.
• frozen lances are laid in the ground to be solidified in one of the desired geometry of the ground area to be frozen, the soil conditions and other conditions adapted number and manner.
• the frozen lances are thereby introduced into boreholes whose inner diameter is slightly larger than the outer diameter of the freezing lances.
• the refrigerant is introduced into the freezing lance closed to the floor area. The heat transfer from the soil to the refrigerant is carried out through the walls of the outer freezing tube or the freezing tube bottom.
• the refrigerant is, for example, a brine or a cryogenic refrigerant such as liquefied nitrogen.
• the refrigerant can be brought into the area of the freezing-tube bottom either via the inner tube which opens out inside the freezing tube or via the annular gap between inner tube and freeze-tube.
• the soil is preferably deprived of heat in the area of the freezing-floor.
• the refrigerant heats up and flows through the annular gap between the inner tube and the freezer tube back to the point of loading.
• liquid knit is passed through the inner tube to the freezer tube bottom, where it evaporates and flows predominantly in the gaseous state through the annular gap.
• the gaseous nitrogen also absorbs heat energy from the soil as it passes through the annular gap.
• the soil is deprived of heat in the area of the charging point. On the way to the freezer tube bottom, the refrigerant heats up and flows back through the inner tube to the charging point.
• each freezer lance is preceded by a solenoid valve.
• the solenoid valve opens and closes depending on the temperature of the exhaust gas flow. The progression of the solidification front is monitored by means of temperature sensors distributed in the ground. Within a short time, usually within a few days, frost bodies of almost any size and shape can be produced.
• the technique of soil freezing is versatile and has proven itself many times.
• the low equipment cost, the short lead times for freezing and short freezing times due to the large difference in temperature between the preferred refrigerant nitrogen (- 196 ° C at atmospheric pressure) and the soil, the production of frost bodies of almost any shapes and dimensions and not least the High availability and the environmental friendliness of nitrogen contribute to the success of the process.
• frozen lances are used, which are constructed of metal tubes.
• the (outer) freezing tube is made of steel and the inner tube of copper.
• Object of the present invention is therefore to improve a device of the type mentioned above and a method for carrying out civil engineering works to the effect that the technique of soil freezing can be used easily and efficiently in these areas.
• the freezing tube and the inner tube consists of a material that can be destroyed by a civil engineering machine without affecting the operational capability of the machine.
• the freezing tube and / or the inner tube at least partially consists of a brittle or soft material.
• a brittle is understood here a material that splinters in the propulsion of a machine or otherwise decomposed into small parts.
• “Brittle” in this sense is also a composite material in which small, unbreakable parts are connected to predetermined breaking points.
• soft here is understood a material that has a much lower hardness than the material of the processing machine. This may be, for example, copper, a copper alloy or plastic.
• the at least partially brittle or soft consistency of the freezing lance makes it possible to leave the freezing lance also in civil engineering work through the frost body in the ground.
• the freezing lances themselves are destroyed during propulsion of the civil engineering machine without damaging the machine itself.
• the remains of the lances are removed with the remaining excavation from the workplace. It is essential that the brittle material content on the one hand withstands the thermal load which arises when charging the freeze lance with the refrigerant, for example liquid nitrogen, and on the other does not affect the ability of the lance body to transfer heat from the ground to the refrigerant.
• the brittle or soft material itself is good heat-conducting, or there are individual sections of a highly conductive, such as metallic material in a frame or matrix construction of a brittle or soft material added. In the latter case, of course, care must be taken to ensure that the size and type of the highly conductive sections are chosen and connected to the remaining parts of the lance in such a way that they can not seriously damage a civil engineering machine.
• the brittle material is, for example, a ceramic or sintered plastic material, which has a high brittleness and at the same time a high density and cold resistance, in order to prevent the outflow of the refrigerant into the surrounding soil.
• the brittle material is preferably a composite of a polymer and a filler, also called “plastic compound".
• a filler also called "plastic compound”.
• Such materials have been known for a long time and are described, for example, in the article by U. Koch: “Verbundsysteme aus PTFE", Construction 6/2001, p. 69. They comprise a matrix of a thermoplastic material, which is preferably polytetrafluoroethylene (PTFE) into which particles of a filler of a mineral or organic material have been added during a sintering process.
• PTFE polytetrafluoroethylene
• any material that is stable at the sintering temperature of the respective plastic can be used as the filler.
• the size, shape and chemical composition of the filler particles substantially determine the physical properties of the composite.
• the mechanical stability and the thermal conductivity of the Adjust composite material in a wide range. It is therefore possible to construct the entire lance body from the composite material.
• the preferred for the inventive freezing lance composite material includes a filler of a thermally highly conductive material, such as carbon in the form of amorphous carbon or graphite, or a metal powder, such as stainless steel, bronze or copper. Due to the thermally highly conductive inclusions in the plastic matrix, the material produced in this way has a significantly improved thermal conductivity compared to pure sintered plastic.
• the metallic material such as stainless steel or copper, which is low in any case compared with the metal materials used to date for the production of frozen lances, can be further reduced in particular by the use of amorphous carbon as a filler.
• amorphous carbon as a filler.
• multiple fillers is conceivable, one of which, for example, a filler for improving the thermal conductivity, another for increasing the brittleness.
• a particularly good thermal conductivity can be achieved in particular in a proportion of 20-60% of the highly conductive material, in particular carbon or graphite, in a PTFE matrix.
• a processing area is equipped with freezing devices and formed in this processing area by charging the freezing devices with a refrigerant frost body.
• the frozen lances used as freezing devices are made of a material that can be destroyed by the propulsion of civil engineering machine without the labor input or the basic operational capability of the civil engineering machine is affected. Subsequently, a civil engineering machine is driven through the equipped with frozen lances machining area. The thereby detected by the civil engineering machine and at least partially destroyed frozen lances are removed with the excavation of the processing area.
• the freezing lances according to the invention do not constitute a hindrance to the civil engineering work, since they can be destroyed during propulsion of the machine without the machine being damaged. For the first time it is through possible to carry out earthworks in a frost body equipped with freezing lances; In particular, freezing lances can also be arranged in the area of a later breakthrough in the frost body. As a result, the field of application of soil freezing technology is considerably expanded.
• the freezing lances according to the invention it is possible, regardless of the arrangement of the lances break out openings, tunnels or other geometric shapes of the frost body, without having to use cutting tools for concrete or steel. It can therefore be used with normal excavation tools or machinery of tunneling or civil engineering for excavation.
• the arrangement of the lances can be chosen independently of subsequent processing steps and thus the frost body can be formed in an optimal way for the civil engineering measure.
• the processing area is secured by soil freezing.
• a frost body is formed in the direction of the tunnel boring machine whose diameter is one to two meters larger than the drill diameter.
• the tunnel cross-section is evenly covered with a field of 20 to 30 freezing lances of the type according to the invention, which are then charged with liquid nitrogen.
• the freezing lances are made of a PTFE cementation material with a filler content of 40% amorphous carbon. Due to the thermal contact of the surrounding soil with the -196 ° C cold nitrogen a frost body is formed within 3 to 6 days, which reaches one to two meters deep into the soil. Subsequently, the tunnel boring machine is set in motion.
• the tunneling machine destroys the freezing lances in its working cross-section without damaging or hindering the operation of the machine in a manner that impedes its functioning.
• the tunnel boring machine is withdrawn and built a new field of freezing lances.

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• 2006
  • 2006-02-21 DE DE102006007980A patent/DE102006007980B3/de active Active
• 2007
  • 2007-02-21 PL PL07102774T patent/PL1820903T3/pl unknown
  • 2007-02-21 EP EP07102774.2A patent/EP1820903B1/fr active Active

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