JP2013096210A - Underground continuous body forming method using in-situ soil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an underground continuous body forming method using in-situ soil, for reducing excavation resistance, preventing separate precipitation of a coarse gravel portion, facilitating insertion of a core material, and preventing crash of a groove face.SOLUTION: In a method of forming an underground continuous body 15 by rotating a cutter 11 inserted underground, excavating a groove 13 continuous in a horizontal direction while cutting soil 12, and agitating and mixing in-situ soil 14 and excavation liquid at an original position simultaneously, mixed soil of the in-situ soil 14 and the excavation liquid is thixotropic, and vane shear stress relative value by a pocket vane test is 10% to 85%.

Description

  The present invention relates to a method for creating an underground continuum using in-situ soil that reduces excavation resistance and facilitates insertion of a core material and the like.

  For example, a soil cement underground continuous wall construction method (TRD construction method) is known as a method for producing an underground continuous body (Japanese Patent Laid-Open No. 5-280043). In this TRD method, a chain saw-type cutter post built in the ground is connected to the base machine, the cutter is rotated, the ground is moved laterally while excavating, the groove is excavated, and soil and cement milk are simultaneously produced. The soil cement wall is formed by mixing the earth and sand and the hardening liquid at the original position by ejecting a hardening liquid such as the above. And, core material such as H steel is built in this underground continuous wall, and it can be used as a retaining wall or water blocking wall during underground excavation, and also for various applications such as liquefaction countermeasures and ground reinforcement. It is possible.

  Japanese Patent Application Laid-Open No. 2003-120174 discloses a face stabilization method in a shield method that maintains the stable state of the face, and the face retaining mud that has permeability to the ground and has a ground improvement effect is disclosed in The shield stabilization method and the shield method in which bentonite and an acrylamide polymer flocculant are blended in the shield method to allow the entire infiltration area of the ground infiltrated from the ground into the ground to be self-supported. The face retaining mud is disclosed. This makes it possible to hold the face well and perform stable excavation work.

Japanese Patent Laid-Open No. 5-280043 JP 2003-120174 A

  However, in the conventional TRD method, the mixed soil of the hardening liquid and in-situ soil has poor fluidity when, for example, the hardening liquid is mixed and the amount of coarse gravel is large, and the excavation occurs when the coarse gravel is bitten by the stirring blade. Due to the large resistance, there is a problem that the excavation is impossible and the groove wall tends to collapse. Also, if you increase the amount of hardened liquid injected from the ground to eliminate this inability to excavate, it will be difficult to build the core material by separating and sinking the gravel, increasing the amount of mud due to the increased injection amount, For example, there are problems such as disposal costs increasing and becoming uneconomical.

  Japanese Patent Laid-Open No. 2003-120174 is a face stabilization method for maintaining the stable state of the face since the entire infiltration area of the ground into which the face retaining mud has infiltrated is provided, It is a face stabilization solution used for excavating while balancing the amount of soil removed. When the face stabilization liquid is applied to the TRD method, the wall of the groove can be prevented from collapsing. However, since the face stabilization liquid has a high water content and is diluted, it cannot prevent the sedimentation and sedimentation of the coarse gravel. Therefore, a problem occurs in the insertion of the core material. Thus, conventionally, there has been no method that satisfies the prevention of the collapse of the groove wall, the reduction of the excavation resistance, and the stable installation of the core material.

  Therefore, the object of the present invention is to reduce the digging resistance when disturbed, prevent separation and sedimentation of coarse gravel when not disturbed, facilitate the insertion of core material, etc., and prevent the collapse of the groove wall. An object of the present invention is to provide a method for constructing an underground continuum using the above.

  In this situation, the present inventor has intensively studied. As a result, in the TRD method, the mixed soil of the in-situ soil and the drilling fluid has a vane shear stress value when disturbed by the pocket vane test and a vane shear stress when undisturbed. If the mixed soil has thixotropy such as 10% to 85% of the value, the excavation resistance is reduced, separation and sedimentation of the gravel is prevented, the core material is easily inserted, and the groove wall The inventors have found that the collapse is prevented, and have completed the present invention.

  That is, the present invention excavates a continuous groove in a horizontal direction while cutting the ground with a rotary cutter inserted into the ground, and simultaneously agitates and mixes the original soil and the drilling fluid at the original position, The mixed soil of the in-situ soil and the drilling fluid has a vane shear stress value in the pocket vane test at the time of disturbance of 10% to 85% of the vane shear stress value in the pocket vane test at the time of undisturbed. It is an object of the present invention to provide a method for creating an underground continuum using in-situ soil, which is characterized.

  According to the present invention, the mixed soil of the in-situ soil and the drilling fluid has thixotropic properties. The thixotropy is that when undisturbed, the aggregates contain water and the viscosity increases. During stirring, stress is applied, so the water trapped in the aggregates is released and the viscosity of the mixed soil decreases. This refers to the property of increasing fluidity. That is, the mixed soil has a high viscosity in the undisturbed state and is lower than the viscosity in the undisturbed state in the disturbed state. For this reason, the cutter torque value at the time of cutter cutting in the TRD method is reduced, the viscosity is restored when the core material is built in, the stability of the groove wall is ensured, and the collapse of the groove wall can be prevented. Moreover, since there is no separation of coarse gravel, the core material can be easily inserted. As another effect, since the underground continuum can be formed even with a small amount of drilling fluid to be injected, the amount of sludge treatment is reduced and it is economical.

It is a figure explaining the underground continuum formation method using the in-situ soil in embodiment of this invention, and a process progresses in order of (A), (B) and (C). It is the schematic which looked at FIG.1 (C) from the top. The schematic diagram of the in-situ mixing stirring soil which has the thixotropic property of this invention is shown. It is a figure explaining a pocket vane test device and a test method. The schematic diagram of the in-situ mixed stirring soil which does not show the conventional thixotropic property is shown.

  An underground continuum formation method using an in-situ soil according to an embodiment of the present invention (hereinafter, also simply referred to as “underground continuum formation method”) will be described with reference to FIGS. As an apparatus for carrying out the underground continuum formation method (hereinafter also referred to as “underground continuum formation apparatus”), for example, a known apparatus described in JP-A-5-280043 can be used. .

First, the rotary cutter 11 of the underground continuous body forming device 10 is inserted into the ground (FIG. 1). Next, the rotary cutter 11 inserted into the ground is rotated to form a continuous groove 13 in the horizontal direction while cutting the ground 12, and at the same time, the in-situ soil 14 and the drilling fluid are stirred and mixed in the in-situ, A continuous body 15 is formed (FIG. 2). In FIG. 1, for the sake of brevity, the drilling fluid and the drilling fluid supply means are not shown, but the drilling fluid is supplied from the ground to the drilling position by a pump.
Moreover, when supplying solidification liquid, such as cement milk, to an in-situ soil, the underground continuous body formation apparatus 10 is attached with the supply means of solidification liquid. In addition, the underground continuous body forming apparatus 10 may be additionally provided with a drilling fluid I supply unit and a thixotropic agent mixture liquid supply unit.

  The drilling fluid includes bentonite or clay mineral, water and thixotropic agent (hereinafter also referred to as “one-part drilling fluid”), drilling fluid I containing bentonite or clay mineral and water, and thixotropic agent. And a thixotropic agent-containing liquid containing water (hereinafter also referred to as “two-part drilling fluid”) supplied to the in situ soil by separate systems. Bentonite or clay mineral forms aggregates by the thixotropic agent. Examples of clay minerals include montmorillonite minerals, kaolinite minerals, and general clay minerals. Bentonite or clay mineral may be fine particles having a particle diameter of 1 to 5 μm.

  In a one-part drilling fluid, the thixotropic agent is blended in a slurry containing bentonite or clay mineral (fine particles) having a particle size of 1 to 5 μm so that the fine particles are bonded to each other. Aggregates can be formed. And after mixing with in-situ soil, when undisturbed, the aggregates contain water, so the viscosity increases, and during stirring, the stress is added and the water trapped in the aggregates is released. The viscosity of the mixed soil decreases and the fluidity increases. In addition, in the case of supplying a thixotropic agent-containing liquid to a mixed soil of, for example, in-situ soil and excavating liquid I in a two-part drilling fluid, the thixotropic agent is bentonite or clay having a particle size of 1 to 5 μm in the mixed soil. Aggregates between fine particles in mineral (fine particles) to form aggregates of 20 to 50 μm in the mixed soil, the same action as described above occurs, and thixotropic properties are expressed in the mixed soil.

  In the present invention, as a method for supplying the two-part drilling fluid to the in-situ soil, a method of simultaneously supplying the drilling fluid I and the thixotropic agent-containing solution, or a method in which the drilling fluid I is first supplied and the in-situ soil and the excavation are excavated. There is a method in which a mixed soil of liquid I is formed, and then a thixotropic agent-containing liquid is supplied to the mixed soil of in-situ soil and excavating liquid I. Thereby, bentonite or clay mineral is aggregated by the thixotropic agent to form aggregates of 20 to 50 μm.

  Examples of the thixotropic agent include an anionic polymer agent. Examples of the anionic polymer agent include homopolymers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, acrylamide 2-methylpropane sulfonic acid, vinyl sulfonic acid, styrene sulfonic acid, and copolymers with acrylamide. . As the anionic polymer agent, either a natural product or a synthetic product can be used, but it is preferable to use a synthetic product in that a fluidized product can be obtained with a small blending amount. These polymer agents can be produced by a known method described in Japanese Patent Publication No. 34-10644.

  A preferred polymer agent is an oil having a molecular weight of 1 million or more, preferably 2 million or more and 10 million or less, and an acrylic polymer having an ionization degree of 0 to 100 mol% and a dispersed particle size of 100 μm or less. It is in the form of a water-in-water emulsion.

In one-part drilling fluid, the blending ratio of bentonite or clay mineral, water, and thixotropic agent may be blended so that the specific gravity of the drilling fluid is 1.01 to 1.3. Specifically, the weight ratio (V) :( W) of bentonite or clay mineral (V) and water (W) in the drilling fluid is 1: 1.5 to 1:70, preferably 1: 1. .6 to 1: 59.5. Further, the mixing ratio of the thixotropic agent in the drilling fluid cannot be generally determined because the amount added varies depending on the drilling ground, but is generally 0.1 to 50 kg, preferably 1 per 1 m ^{3 of} bentonite or clay mineral. About 10 kg. Such a drilling fluid can be obtained by adding bentonite or clay mineral and a thixotropic agent in water and stirring and mixing the resulting drilling fluid, 20-50 μm comprising bentonite or clay mineral and a thixotropic agent. The aggregates are uniformly dispersed. Such a one-part drilling fluid is stirred and mixed with the in-situ soil, so that the mixed soil exhibits thixotropic properties. The drilling fluid may contain cement as an optional component.

In the drilling fluid I of the two-component drilling fluid, the weight ratio (V) :( W) of bentonite or clay mineral (V) and water (W) is 1: 1.5 to 1:70, preferably 1. : 1.6 to 1: 59.5. The proportion of the thixotropic developer liquid combination for drilling fluid I, since the amount of use varies by excavating the ground, although can not be determined unconditionally, generally drilling fluid I 1 m ³ per thixotropic developer is 0.1～50Kg, Preferably, it may be used so as to be 1 to 10 kg. In the mixed soil of the drilling fluid I, the thixotropic agent blending solution, and the in-situ soil, aggregates of 20 to 50 μm composed of bentonite or clay mineral and a thixotropic agent are uniformly dispersed. Such a mixed soil of two-component drilling fluid and in-situ soil exhibits thixotropic properties. Further, the drilling fluid 1 may contain cement as an optional component.

  The in-situ soil 14 is undisturbed soil of the ground to be constructed, and examples thereof include clay ground, gravel ground, sand ground, humus soil, and organic soil.

  In the present invention, the vane shear stress value by the pocket vane test at the time of disturbance of the mixed soil of the original soil 14 and the drilling fluid is 10% to 85%, preferably 20% of the vane shear stress value by the pocket vane test at the time of undisturbed. ~ 70%. Such mixed soil has high thixotropy. The above numerical values are referred to as vane shear stress relative values. If the vane shear stress relative value is less than 10%, the thixotropy does not increase for a large amount of thixotropic agent added, and if it exceeds 85%, the thixotropy does not become high, and the cutter torque value at the time of cutter cutting is sufficient. It cannot be made smaller.

  The pocket vane test device is a manual vane shear test device based on the standard of the in-situ vane shear test (JGS 1411), and obtains the maximum strain value and the minimum strain value of the shear stress of the measurement sample from the rotational resistance of the vane. The thixotropy is obtained from this ratio.

  A method for measuring the thixotropy of a measurement sample using a pocket vane test apparatus will be described with reference to FIG. FIG. 4A is a schematic view of a pocket vane test apparatus. The pocket vane test apparatus 40 is composed of a manual rotary handle 41, an upper end connected to the manual rotary handle 41, and a vane shaft 42 having a vane blade 43 at a lower portion. The blades are combined so as to form a cross shape, and the ratio of the height and width of the blades is 2.0. Reference numeral 45 is a vane rotation torque display circle, and reference numeral 46 is a vane rotation torque indicating needle. Reference numerals 42 and 43 are referred to as vanes. FIG. 4 (A) is a diagram showing a state in which the vane blade 43 penetrates into the center of the sample soil 44 placed in a beaker, and FIG. FIG. 4C is a schematic diagram in which a vane is turned by turning the vane in (B), and the vane is turned by the disturbed sample.

  As a method for measuring the thixotropy of the measurement sample 44 using the pocket vane test apparatus 40, first, as shown in FIG. 4A, the pocket vane blade 43 is slowly penetrated so as to be positioned at the center of the undisturbed sample. . Next, as shown in FIG. 4B, the vane manual rotation handle 45 is rotated in the direction of the symbol X as slowly as possible. The value of the vane rotation torque display at this time is the maximum strain value indicated by reference numeral 47 (the vane shear stress value when undisturbed). The sample further rotated from the state of FIG. 4 (B) becomes a disturbed sample as shown in FIG. 4 (C), and the sample which converges from the maximum strain value and is indicated by reference numeral 48 after about 3 rotations is the minimum. Strain value (vane shear stress value during disturbance). The ratio of the minimum strain value to the maximum strain value is obtained, and this is set as the vane shear stress relative value.

  In order to make the relative value of the vane shear stress of the mixed soil within the above numerical range, several samples were prepared by mixing the soil collected from the target ground (in-situ soil) with the drilling fluid and mixing ratio in the laboratory. Then, for these several types of mixed soil, the relative value of the vane shear stress is obtained using the pocket vane test device 40, and the amount of drilling fluid used may be determined from the result (hereinafter referred to as “laboratory drilling fluid determination method”). ").

  Next, the thixotropy of the mixed soil of the original soil 12 and the drilling fluid will be described with reference to FIG. FIG. 3A is a schematic diagram of the current position soil. The in-situ soil 30 includes a coarse gravel portion 31 and a fine grain portion 32. (B) is a schematic view after the excavation liquid is put into the in-situ soil of (A) and mixed with stirring. In the mixed soil (B), the gravel portion 31 and the aggregate 33 are mixed. The aggregate 33 is formed by combining bentonite or clay mineral in the drilling fluid and fine particles of the in situ soil, and water is included in the aggregate. Therefore, the mixed soil of (B) has a high viscosity in an undisturbed state. For this reason, collapse of the groove wall 151 of the groove 13 is prevented, and the coarse gravel portion 31 is difficult to settle. When the coarse gravel portion 31 settles, the coarse gravel portion 31 accumulates on the groove bottom of the groove 13 and the tip of the core material 16 may not enter deeply. However, in the present invention, the coarse gravel portion 31 does not settle. As shown in FIG. 1C, the core material 16 can be easily inserted.

  In FIG. 3C, a force is applied in the direction of the arrow to the mixed soil of the in-situ soil 14 and the drilling fluid of (B), and the mixed soil exhibits thixotropic properties. The thixotropy is that when undisturbed, the aggregates contain water and the viscosity increases. During stirring, stress is applied, so the water trapped in the aggregates is released and the viscosity of the mixed soil decreases. A phenomenon that increases fluidity. That is, as shown in FIG. 3C, when a force acts on the mixed soil, the water confined in the aggregate 33 is released, the viscosity of the mixed soil is reduced, and the fluidity is improved. Such thixotropic properties are manifested in the vicinity of the cutter 11 where the force acts and the core material insertion portion in the mixed soil of FIG. For this reason, excavation resistance reduces and insertion of the core material 16 becomes easy (FIG.1 (C)).

  With reference to FIG. 5, the behavior of the conventional soil 14 and the mixed soil of the drilling fluid will be described as a comparative example of the present invention. FIG. 5A is a schematic diagram of the current position soil. The in-situ soil 60 includes a coarse gravel portion 61 and a fine grain portion 62. (B) is a schematic diagram after the excavating liquid in which the thixo-expressing agent is not blended is added to the in-situ soil of (A) and stirred and mixed. In the mixed soil (B), the coarse gravel portion 61, the fine particle portion 62, and the fine particles 63 present in the drilling fluid are mixed. Therefore, in the mixed soil of (B), the coarse gravel portion 61 does not have aggregates containing water as in the present invention, and therefore can move freely as indicated by the arrow, and the viscosity is undisturbed in the undisturbed state. It is low. For this reason, collapse of the groove wall 151 of the groove 13 cannot be prevented, and the coarse gravel portion 61 tends to settle. When the coarse gravel portion 61 sinks, the coarse gravel portion 61 may accumulate at the groove bottom of the groove 13 and the tip of the core material 16 may not enter deeply.

  In FIG. 5C, a force is applied to the mixed soil of the in-situ soil 14 and the drilling fluid in (B), and the mixed soil does not have thixotropic properties. That is, as shown in FIG. 5 (C), when a force acts on the mixed soil, fluidity deteriorates due to friction between the gravel portions 61 and excavation resistance increases. As described above, in the underground continuum formation method, the effect to be achieved is significantly different between the case where the mixed soil of the in-situ soil 14 and the excavating liquid has thixotropy.

  In the present invention, the in-situ soil and the drilling fluid are stirred and mixed in the original position to form the underground continuum 15, but the same amount of mixed soil as the drilling fluid is drained during the stirring and mixing. Since the drilling fluid used in the present invention contains a thixotropic agent, if the amount of drilling fluid is the same, a small amount of bentonite or clay mineral may be added compared to the conventional one. For this reason, the amount of mud is also small, and the environmental load is reduced.

  In the present invention, the drilling liquid and the hardening liquid can be supplied independently and simultaneously, and the drilling liquid can be supplied after the hardening liquid is supplied. When supplying the drilling liquid and the hardening liquid independently, one is the bentonite or clay mineral according to the present invention, the drilling liquid formed with water and the thixogene, and the other is the hardening liquid formed with water and cement. can do.

  In the present invention, as a method for supplying the drilling liquid and the hardening liquid independently, for example, the in situ soil and the hardening liquid are stirred and mixed in the original position. At this time, the supply of drilling fluid is stopped. When the cutter bites the in-situ soil by monitoring the agitation and mixing state on the ground, and the excavation resistance increases, the excavating fluid of the present invention is supplied, and the mixed soil of the in-situ soil and the excavating fluid is vane sheared. The stirring mixing resistance is reduced as the range of the stress relative value. In this method, in the laboratory drilling fluid determination method for determining the relative value of the vane shear stress, the target soil to which the drilling fluid is blended is a blend of a hardener such as cement milk.

  In the underground continuous body formation method in the present invention, when performing the conventional three-pass construction method of excavation (1 pass), return (2 passes), hardening liquid injection (3 passes), and core material insertion, excavation during excavation is performed. The liquid may be used as the one-part drilling fluid or the two-part drilling fluid of the present invention. Moreover, when performing the conventional 1-pass construction which makes excavation, hardening | curing liquid injection | pouring, and core material insertion a series of work, what is necessary is just to supply the digging liquid and hardening liquid which concern on this invention each independently simultaneously.

(Example)
EXAMPLES Next, although an Example is given and this invention is demonstrated more concretely, this is only an illustration and does not restrict | limit this invention.

Reference example (investigation of the ground to which the method of the present invention is applied)
The ground (in-situ soil) to which the method of the present invention is applied in the K station elevated construction, and the vane shear stress of the mixed soil of the in-situ soil and the drilling fluid prepared in the laboratory using a pocket vane test device. Relative values were measured. The drilling fluid A uses a mixture of 29.6 kg of bentonite having a particle size of 1 to 5 μm, 988 kg of water, and a copolymer of acrylic acid and acrylamide (thixo-expressing agent). The amount of the thixotropic agent was 0, 5, 7.6, and 10 kg per 1 m ^{3 of} the drilling fluid. The diameter of the vane blade of the pocket vane test apparatus was 2 cm, and the vane shear stress (N / m ² ) was calculated from the formula: (6 × Mf) / (7πB ³ ). In the formula, Mf represents the rotational moment (N · cm), and B represents the diameter (cm) of the vane blade. As for the ground (original position soil), number 1 is the target ground on the first construction day, number 2 is the target ground on the second construction day, and number 3 is the target ground on the third construction day. The results are shown in Table 1. A vane shear stress relative value of 20% to 83% exhibits high thixotropy, and the cutter torque value during cutter cutting in the TRD method can be reduced. It was confirmed that the stability of

(Preparation of drilling fluid)
A mixture of 155 kg of bentonite with a specific gravity of 2.5 and a particle size of 1 to 5 μm and 938 kg of water is blended with 1.5 kg of a copolymer of acrylic acid and acrylamide (thixotropic agent) per 1 m ^{3 of} the mixture. The drilling fluid was prepared. The specific gravity of the drilling fluid was 1.1.

(Preparation of curable liquid)
A hardening liquid was prepared by mixing 50 kg of a clay mineral having a particle diameter of 1 to 5 μm, 800 kg of water, and 547.2 kg of blast furnace cement type B having a specific gravity of 3.04.

(Construction of underground continuum)
Using a TRD-III type machine with an applied wall depth of 30 m and an applied wall thickness of 550 to 850 mm, the TRD method was carried out on gravel ground mixed with clay. That is, excavation, injection of hardening liquid, and erection of the core material were performed as a series of operations in one pass. The drilling liquid and hardening liquid were supplied independently, and the excavation resistance of the cutter was confirmed by monitoring the construction machine.

First, construction was carried out without using the drilling fluid, but by feeding the hardening fluid to the gravel ground at 91.4 liters / m ³ . As a result, during construction, the groove wall collapsed and bitten into the cutter, making it impossible to excavate. For this reason, construction was stopped and the core material was not installed.

In order to improve fluidization and to ensure fluidity when the core material is installed, a new mixture of 938 kg of water and 155 kg of clay was added to the liquefied liquid through a separate route, 180 liters / m ^3. As a result, the gravel was separated and settled, making it difficult to build the core material.

Therefore, construction was carried out while introducing the prepared drilling fluid into the gravel ground through another route at 150 liters / m ³ . The relative value of the vane shear stress of the mixed soil at this time was 36%. From this value, the mixed soil showed high thixotropy.

  As a result, the collapse of the groove wall has been eliminated, and the excavation resistance has significantly decreased from 250 kN · m to 180 kN · m. The subsequent core material insertion could be performed very smoothly.

  According to the present invention, the excavation resistance can be reduced during disturbance, the viscosity becomes high when undisturbed, and the collapse of the groove wall is prevented. Moreover, since there is no separation of coarse gravel, the core material can be easily inserted. For this reason, an efficient TRD construction method can be implemented.

DESCRIPTION OF SYMBOLS 10 Excavator 11 Cutter 12 Ground 13 Groove 14, 30, 60 In-situ soil 15 Underground continuum 16 Core material 20 Rotational viscometer 31, 61 Coarse particles 32, 62 Fine particles 33 Aggregates 40 Pocket vane test device 43 Vane Blade

That is, the present invention excavates a continuous groove in a horizontal direction while cutting the ground with a rotary cutter inserted into the ground, and simultaneously agitates and mixes the original soil and the drilling fluid at the original position, The mixed soil of the in-situ soil and the drilling fluid has a vane shear stress value of 10% to 70 % of the vane shear stress value by the pocket vane test at the time of disturbance without disturbance. It is an object of the present invention to provide a method for creating an underground continuum using in-situ soil, which is characterized.

That is, according to the present invention, a rotary cutter inserted into the ground excavates a continuous groove in the horizontal direction while cutting the ground, and simultaneously agitates and mixes the original soil, the excavating liquid, and the hardening liquid at the original position, In the method of creating a middle continuum, first, the hardening liquid is poured into the in-situ soil, the in-situ soil and the hardening liquid are stirred and mixed, and excavation is performed until the rotary cutter bites the in-situ soil and the construction becomes impossible. and then a curing liquid situ soil, bentonite or clay minerals, a drilling fluid containing water and a thixotropic enhancer was charged, there is stirring mixed construction, the raw position soil with the drilling fluid and the hardening liquid Mixed soil is an underground soil using in-situ soil characterized in that the vane shear stress value by the pocket vane test at the time of disturbance is 10% to 70% of the vane shear stress value by the pocket vane test at the time of undisturbed Proposed continuum creation method It is intended to.

First, the rotary cutter 11 of the underground continuous body forming device 10 is inserted into the ground (FIG. 1). Next, the rotary cutter 11 inserted into the ground is rotated to form a continuous groove 13 in the horizontal direction while cutting the ground 12, and at the same time, the in-situ soil 14 and the drilling fluid are stirred and mixed in the in-situ, A continuous body 15 is formed (FIG. 2). In FIG. 1, for the sake of brevity, the drilling fluid and the drilling fluid supply means are not shown, but the drilling fluid is supplied from the ground to the drilling position by a pump. Moreover, when supplying hardening liquid, such as cement milk, to an in-situ soil, the underground continuous body formation apparatus 10 is attached with the supply means of hardening liquid. In addition, the underground continuous body forming apparatus 10 may be additionally provided with a drilling fluid I supply unit and a thixotropic agent mixture liquid supply unit.

In the present invention, as a method for supplying the drilling liquid and the hardening liquid independently, for example, the in situ soil and the hardening liquid are stirred and mixed in the original position. At this time, the supply of drilling fluid is stopped. Then, by monitoring the agitation and mixing state on the ground, if the cutter bites the in-situ soil and the excavation resistance increases, supply the in-situ soil and bentonite or clay mineral, water and excavation Stir mixing resistance is reduced by setting the mixed soil of the liquid and the hardening liquid in the range of the relative value of the vane shear stress. In this method, in the laboratory drilling fluid determination method for determining the relative value of the vane shear stress, the target soil to which the drilling fluid is blended is a mixture of a hardening fluid such as cement milk.

Claims (5)

  In a method of excavating a continuous groove in the horizontal direction while cutting the ground with a rotary cutter inserted into the ground, and simultaneously stirring and mixing the original soil and the drilling fluid at the original position, The mixed soil of the in-situ soil and the drilling fluid is characterized in that the vane shear stress value by the pocket vane test at the time of disturbance is 10% to 85% of the vane shear stress value by the pocket vane test at the time of undisturbed. Underground continuum creation method using in-situ soil.   The ground excavation method according to claim 1, wherein the drilling fluid contains bentonite or clay mineral, water and a thixotropic agent.   The drilling fluid is characterized in that the drilling fluid I containing bentonite or clay mineral and water and the thixotropic agent-containing liquid containing thixotropic agent and water are respectively supplied to the in situ soil by separate systems. The underground continuum formation method using the in-situ soil of Claim 1.   The underground continuum formation method using the in-situ soil according to any one of claims 1 to 3, wherein the thixotropic agent is an anionic polymer agent.   The ground using the in situ soil according to claim 2 or 3, wherein bentonite or clay mineral having a particle diameter of 1 to 5 µm is formed into aggregates having a particle diameter of 20 to 50 µm by a thixotropic agent. Continuous body creation method.

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