JPH02125091A - Friction reduction method for underground propulsive body using foaming solid - Google Patents

Abstract

PURPOSE:To reduce friction between an underground propulsive body and an outer peripheral bedrock and stabilize a peripheral ground by a method wherein a mixture of a foaming solid substance and a lubricant for propulsion is fed to a bedrock being the outer periphery of the underground propulsive body, e.g., a shield excavator. CONSTITUTION:When an underground propulsive body, e.g., an earth pressure type shield excavator 1, is thrust forward, a mixture of a foaming solid substance and a lubricant for propulsion is fed from an injection tank 6. The mixture is injected toward an outer peripheral bedrock 8 through an injection port 5 by means of an injection pipe 4 with the aid of a pump 7. A bearing effect is produced between the underground propulsive body and the outer peripheral bedrock 8 to reduce friction. A change in a volume of the foaming solid is produced according to expansion and deformation compression of the peripheral bedrock to stabilize the peripheral bedrock.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a method for reducing friction of an underground propellant using a solid foam, and more specifically, to a Tonosho-type shield excavator, a semi-shield machine in a propulsion method, The present invention relates to a method for reducing the friction of a propulsion tube against the outer ground.

[Conventional technology]

In the shield construction method, as the Tonosho-type shield excavator penetrates the face, large surrounding friction occurs due to ground reaction force, causing large displacement of the surrounding ground, and the propulsive force of the shield jack increases, causing a crank in the segment. There were problems such as damage and, in some cases, damage.

In the propulsion method, the semi-shield machine, lead pipe, and underground pipe are pushed into the ground, so if the propulsion distance becomes long, the movement between the semi-shield machine, lead pipe, and underground pipe and other surrounding mountains ( When frictional resistance increases, the jacking thrust increases, and the propulsion force increases further, and when the propulsion force exceeds the allowable resistance of the underground pipe, it becomes impossible to propel the pipe further.

In order to improve these problems, conventional lubricants mainly made of bentonite, waste oil, and superabsorbent resin have been injected into the surrounding ground to reduce the Pj friction force between the propellant and the surrounding ground. Measures were taken to reduce this.

[Problem to be solved by the invention]

By the way, in conventionally used propulsion lubricating materials, bentonite is mainly composed of clay Ff and montmorillonite, which has a large surface active force and excellent swelling and lubricity, but it is diluted in groundwater and reduces friction. If the effect is lost or it dissolves in groundwater, it will become alkaline (PH = 1) ~ 12
Because of this extremely high concentration, alkali pollution often occurred.

Further, although oil-based materials have excellent lubricity, they may flow into groundwater and cause groundwater contamination.

Furthermore, superabsorbent resin is dissolved in a solvent and sprayed onto the surrounding ground, making it spherical due to its high water absorption properties in order to reduce the frictional force with the surrounding ground, but there are cations in the solvent. However, there are disadvantages such as the resin itself being easily deteriorated and being sensitive to sunlight, and the material costs are also high, so it is often not economical.

The purpose of this invention was to solve the above-mentioned problems with conventional propulsion slipping materials. It is an object of the present invention to provide a method for reducing friction of an underground propellant using a foamed solid body, which can reduce friction and enable stable propulsion regardless of changes in groundwater conditions.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention supplies a mixture of a foamed solid body and a propulsion slipping material to the outer periphery of an underground propellant, and This is designed to reduce the friction between the medium propellant and the outer ground.

[Effect]

By supplying a mixture of solid foam and propulsion lubricant to the outer ground of the underground propellant, a hair ring effect is created between the propellant and the outer ground, reducing friction. At the same time, due to the volume change of the foamed solid body, it is possible to cope with the expansion, deformation and compression of the surrounding ground, thereby making it possible to stabilize the surrounding ground.

[Example] Hereinafter, an example of the present invention will be described based on the accompanying drawings.

Figures 1 and 2 show examples used in the propulsion method. In the figures, 1 is a shield type excavator, 2 is an underground pipe, and 3 is a press-fit jack inserted into the propulsion shaft 10. Injection pipes 4 are connected to the skin plate 1a of the shield type excavator 1 through injection ports 5 at several locations.

Reference numeral 6 denotes an injection tank that stores a mixed material of a foamed solid body and a shielding and propulsion lubricating material. It is designed to be injected into

The foamed solid body is made of polystyrene foam and is formed into spherical shapes, and is used as a shielding and propulsion slipping material.
Examples include clay, thickeners, high water absorption...fatty materials, etc., and the spherical diameter of the foamed solid and the amount of mixture with the shielding and propulsion lubricant may be appropriately selected depending on the soil quality, etc. .

Note that 9 is a valve interposed in the middle of the injection pipe 4.

Next, the present invention will be explained in detail.

In a propulsion method in which an underground underground pipe 2 is propelled by a shield-type excavation ml at the tip and a press-fit jack 3 in a propulsion shaft 10, the solid foam sent by the pump 7 and the injection pipe 4 and the shielding and propulsion slipping material are used. The mixed material is injected into the surrounding ground 8 from the injection port 5.

This allows it to permeate the entire circumference of the ground 8! !
At the same time as forming the friction reducing layer 1), the peripheral frictional force acting on the underground pipe 2 is reduced by making the surrounding ground 8 self-sustaining and stable in response to the cross-sectional change of the surrounding ground 8 after propulsion. At the same time, the thrust of the press-fit jack 3 is reduced.

In this way, a stable friction-reducing layer 1) can be formed over the entire length of the subsequent underground pipe 2, making it possible to propel the underground pipe 2 over long distances, as well as controlling the injection pressure to the injection pipe. Stable propulsion is possible by adjusting the pressure to a level slightly higher than the hydrostatic pressure using the valve 9 when propulsion is carried out below groundwater, or to a pressure that does not deform other mountains when there is no groundwater.

In addition, although the example shows an example where it is adopted in the propulsion method, it is also possible to supply the above-mentioned mixed material to the outer periphery of the earth pressure type shield excavator to reduce the friction between the Tonosho type shield excavator and the surrounding ground. good.

〔Effect of the invention〕

As described above, according to the present invention, a bearing effect is created between the surrounding ground and the underground propellant by supplying a mixture of foam solids and propulsion slipping material to the underground propellant and the surrounding ground. The expansion, deformation and compression of the surrounding ground can be responded to by changing the volume of the foamed solid body, which has the effect of stabilizing the surrounding ground.

In addition, lubricants whose main component is bentonite may be diluted by groundwater, weakening their friction-reducing effect.
A stable friction-reducing layer of solid foam can be created in the gap between underground objects and the surrounding ground without causing alkali pollution.

Furthermore, if there are cations in the solvent, such as in highly saturated water-based resins, the resin itself may deteriorate, or water absorption may drop dramatically in salt water, making stable propulsion unaffected by changes in groundwater conditions. do.

In addition, when propelling an underground pipe by injecting chemical liquid into soft ground, a stable friction-reducing layer is created by the bearing effect of the solid foam in the gap between the layer solidified by the chemical liquid and the underground pipe. It has the effect of being able to create

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing the state of the propulsion method for implementing the method of the present invention, and the second leap is a cross-sectional view taken along the arrows ■■ in FIG. 1. 1...Tonosho type shield excavator, la...
・Skin plate, 2... Buried pipe, 3... Press-fit jack, 4... Injection pipe, 5...
... Inlet, 6... Injection tank, 7...
...Pump, 8...Other surroundings, 1...Friction reduction layer. same

Claims (4)

[Claims] (1) A mixture of foamed solid material and propulsion lubricant is supplied to the surrounding ground of the underground propellant to reduce friction between the underground propelled object and the surrounding ground. Method for reducing friction in medium propellants. (2) The method for reducing friction of an underground propellant using a foamed solid body according to claim 1, wherein the underground propellant is an earth pressure type shield excavator, a semi-shield excavator, or an underground pipe. (3) A method for reducing friction in an underground propellant using the foamed solid body according to claim 1, wherein the foamed solid body is formed of a polystyrene foam. (4) The method for reducing friction of an underground propellant using a foamed solid according to claim 1, wherein the propulsion slipping material is clay, a thickener, or a super absorbent resin material.