JP2014029062A - Construction method of soil cement continuous wall - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a construction method of a soil cement continuous wall with which increase in the quantity of mud can be suppressed by preventing cement milk of an injection material from being increased considerably, even in the case of construction without performing pre-drilling that becomes double labor on a hard ground.SOLUTION: A mix proportion of the quantity of cement to be added to cement milk of lean-mix to be injected into source position soil from the start of drilling to reaching planned depth per object soil 1 mis equal to or less than 25% of the quantity of cement per object soil 1 mfinally required for constructing a wall, and a water/cement ratio (W/C) is equal to or less than 600%. When lifting a screw from the reached planned depth to a position of the start of drilling, the quantity resulting from subtracting materials of cement milk injected from the start of drilling to reaching the planned depth from all additives required for constructing the wall is injected as cement milk of rich-mix.

Description

  The present invention is a soil which excavates the ground by a construction machine such as a multi-axis auger, injects an injection solution containing a solidified material into the current soil, mixes and agitates, and constructs a column wall of soil cement in the ground It relates to the construction method of cement continuous wall.

  The soil cement continuous underground wall is manufactured by mixing the excavated soil and a hardened material such as cement milk when excavating with an earth auger. It is constructed by pile walls and generates industrial waste residue (mixed with soil cement and raw soil) that exceeds the amount of cement milk injected. And huge costs are required for disposal.

Therefore, in Patent Document 1 below, an amount of excavated soil corresponding to the amount of hardened material such as cement milk injected in advance as a prior excavation is discharged to the ground, and then hardened material such as cement milk is injected simultaneously with further excavation. Then, it was decided to mix the excavated soil and the hardened material in the subsequent excavation, and to perform the previous excavation by a different excavation means from the subsequent excavation and to perform the subsequent excavation by a soil cement pile generator. .
Japanese Patent No. 270081

  According to this, it is the general residual soil as the raw soil that is discharged to the ground by the preceding excavation, and this can be disposed without industrial waste. The mixing of the hardened material such as cement milk and the excavated soil is the one in which the hardened material is filled in the excavated portion, and the excavated soil is generated when the subsequent excavation is performed after the previous excavation. Since it is used to construct a soil cement pile by mixing such hardener and excavated soil, it can be constructed without generating industrial waste residue. Further, since the hardened material such as cement milk is not thrown away with the soil, it is economically utilized without waste.

  However, if the excavation is different from the subsequent excavation, it takes time and labor to replace heavy machinery, and if the auger 1 is not single-axis but multi-axis, the excavation shape is limited to that. Therefore, it is practically impossible to perform the preceding excavation and the subsequent excavation by different excavation means.

On the other hand, the following Patent Document 2 can greatly reduce the generation of ordinary residual soil and industrial waste residual soil, requires only a small amount of hardener injection, has a low construction cost, and does not require time and effort. It was proposed as a method for constructing soil cement piles that can be constructed quickly and accurately.
Japanese Patent No. 3706354

  About 30% of the total length of a soil cement pile construction machine, which is a multi-axis auger, to construct a predetermined length of a construction site filled with a kneading material (soil cement) of hardened material such as cement milk and excavated soil The excavation shaft is divided into an earthing section and a pouring section below it, and the auger is aligned, and the auger is inserted into the earthing section while leaving soil around it as the first stage excavation. A volume of soil is discharged from the ground, and then, as the second stage excavation, stirring excavation is performed while injecting the hardener so that the remaining depth, which is the lower injection section, is filled with the kneading material, and then the third excavation. As the step excavation, the portion of the first step excavation is agitated while injecting a hardening material.

  1-7 is explanatory drawing of each process, FIG. 8 is a schematic diagram, 1 is an auger which is a soil cement pile construction machine in the figure, and is a 5-axis multi-axis auger. As is well known, the earth auger 1 has a drilling head 4 at the tip of a drilling shaft 3 with a screw or a stirring blade that is rotationally driven by a driving device 2 such as a hydraulic motor, and there are five such screw drilling shafts 3. The book is made so that a hardening material such as cement milk passing through the inside of the excavation shaft 3 can be injected from the excavation head 4.

  First, the auger 1 is aligned, and as shown in FIGS. 1 and 8, the auger is inserted at a predetermined length (excavation section) while leaving the soil 10 in the first stage excavation process. This excavation is performed while discharging air 12 from the excavation head 4. In this case, the soil 10 having only the volume of the excavation shaft 3 to be inserted is discharged to the ground and piled on the ground. In FIG. 8, a is a predetermined length to be excavated.

  As the second stage excavation process, as shown in FIG. 3, the remaining depth below is continuously hardened so as to be filled with a kneading material (soil cement) 9 of hardened material 5 such as cement milk and excavated soil. While the material 5 is being injected, the agitation excavation is performed for a predetermined length a (soil removal section + injection section).

  In the second stage excavation process, the soil 10 left around the periphery serves as a plug to prevent the hardened material 5 from leaking to the ground. Although it may ooze out from the periphery of the auger 1 slightly, the amount is small. In particular, since there is soil 10 that is discharged to the ground and piled up as described above, the effect as a plug is great, and the leakage of the hardened material 5 to the ground can be prevented.

  Further, the hardened material 5 poured out into the soil of the second stage excavation in a state where the upper portion is closed with the soil 10 penetrates into cracks and the like of the hole wall by the injection pressure to make the hole wall dense.

  Further, as shown in FIG. 8B, in the portion of the soil 10, the hardener 5 injected in the second stage excavation process pushes up the lower side and penetrates to become a hardener permeation portion 11a.

  After the auger 1 reaches the depth of the full length (predetermined length α) as shown in FIG. 3, repeated stirring is performed as shown in FIG. 4, and by reverse rotation while injecting the curing material 5 as shown in FIG. 5. Pull up with stirring. The hardening material 5 to be injected at this stage also pushes up the lower side of the soil 10 and the hardening material permeating portion 11a to become a hardening material permeating portion 11b.

  Next, as shown in FIG. 6, as the third stage excavation process, the first stage excavation site, that is, the soil 10 and the hardener penetration portions 11a and 11b are stirred while the hardener 5 is injected. This agitation is turning that moves the auger 1 up and down.

  The agitation in the third stage excavation process may be performed upward from the lower end position of the location of the first stage excavation, or may be performed downward from the upper end position of the location every time the first floor excavation is performed. However, the third stage excavation can be transferred as it is without lifting the auger 1 to the ground from the second stage excavation process.

  In the latter case, the auger 1 is once pulled up to the ground and inserted again in order to inject and stir the uninjected portion of the hardening material 5.

  In the above-described process of the present invention, the amount of soil removal and the amount of hardener injected will be described. In the first stage excavation in FIG. 8 (a), the insertion of the auger 1 is about 30% of the total length α, and the remaining In the second stage excavation for a depth of 70%, about 40% of the soil 10 filling the periphery of the auger 1 of the first stage excavation is pushed up to the ground, and 60% remains.

  Furthermore, the injection of the hardener 5 in the third stage excavation after both of the hardener penetration portions 11a and 11b are formed may be small according to the amount of residual sediment in the hole.

  Thus, the general residual soil is left in the upper end portion of the excavation hole and is plugged, and the lower portion thereof is filled with the hardener 5 by excavation, and all of the excavated soil at the time of the lower excavation is mixed with the hardener 5. Because it is used as soil cement, it can be constructed with little industrial waste residue.

  In the case of hard ground that cannot be drilled at the drilling speed originally planned in the middle of drilling in multi-axis drilling, the cement milk produced in the plant remains at the original planned pumping speed and is hard thereafter. Since the ground range cannot be predicted, continuous pumping is performed, and as a result, a large amount of cement milk is discharged to the hard ground range where the drilling speed is extremely reduced. As a result, the soil to be drilled outside the hard ground area lacks the cement milk necessary for the originally planned wall making, so it is necessary to increase the amount of cement milk.

  Moreover, since the total amount of cement milk to be injected increases, the amount of mud discharged increases.

  In Patent Document 1 and Patent Document 2, prior excavation is performed, and what is dumped on the ground is general residual soil as raw soil, which can be disposed of without industrial waste. However, depending on the soil type, performing a pre-excavation may be a double effort, and it may not be possible to pre-exclude everything.

  In this way, soil cement can be used to prevent a significant increase in the cement milk of the injection material and to suppress an increase in the amount of mud soil even when construction is carried out without a prior drilling that is a double effort on hard ground. Provides a method for constructing continuous walls.

  The object of the present invention is to eliminate the inconvenience of the above-mentioned conventional example, and to prevent a significant increase in cement milk in the injecting material even when construction is performed without hard drilling that requires double labor on hard ground. An object of the present invention is to provide a soil cement continuous wall construction method capable of suppressing an increase in the amount of mud.

In order to achieve the above-mentioned object, according to the present invention, the composition per 1 m ³ of the target soil of the amount of cement added to the poorly blended cement milk to be poured into the in situ soil from the start of drilling until reaching the planned depth is finally a wall-making less than 25% of the target soil 1 m ³ per cement amount required, water-cement ratio (W / C ratio) is set to 600% or less, planning depth at the time the screw pulled up drilling start position from the arrival, plans from drilling start depth Inject the amount of cement milk that has been injected to reach the total amount required for the building wall from the total amount of additive, and inject it as a rich blend of cement milk, and at the time of lifting, pull up while turning to ensure kneading performance It is a summary.

  According to the present invention of claim 1, the construction is divided into two passes from the start of excavation to the arrival of the drilling hole and from the arrival to the pulling up, and the total cement injection amount of both is not significantly changed from the conventional one, When cement milk of poor mix (low weight ratio of water to cement-based solidified material (W / C ratio) is low) is injected from the start to the end of drilling, so that it becomes a drilling hole for a large amount of water and the soil is hard However, the excavation speed does not slow down without performing prior excavation. In this way, even when the soil is hard, the excavation speed does not have to be slow, so there is no significant increase in the amount of mud and cement milk.

  According to the second aspect of the present invention, at the time of pulling up, since it is pulled up and turning while injecting cement milk having a rich blend [the weight ratio of water to cement-based solidified material (W / C ratio) is high], excavation starts. The amount of cement injected into the target soil that combines both the process from drilling to drilling is not significantly changed from the conventional one, and the properties of the soil cement are not impaired.

  As described above, the soil cement continuous wall construction method of the present invention can significantly increase the cement milk in the injecting material even when construction is performed without hard drilling that requires double labor on hard ground. Can prevent the increase in the amount of mud.

  Hereinafter, embodiments of the present invention will be described in detail. The present invention is a case where a soil cement continuous wall is constructed, and a cement-based hardening liquid (cement slurry / cement milk) is injected into an in-situ ground to construct a soil cement column wall.

  In the present invention, the in-situ ground is composed of soil, sand, rocks, and the like, and means a ground in a naturally deposited state before excavation work (that is, before the cement slurry of the present invention is injected).

  In the present invention, the cement-based solidifying material (cement) used in the cement-based hardening liquid (cement slurry / cement milk) includes ordinary Portland cement, early-strength Portland cement, ultra-early-strength Portland cement, moderately hot Portland cement, and low heat Portland cement. Cement-based materials such as cement, sulfate-resistant Portland cement, blast furnace cement, silica cement, fly ash cement, various ground improvement cement-based solidifying materials can be used. Among these, blast furnace cement (type blast furnace B) is particularly preferable.

  The cement hardening liquid (cement slurry / cement milk) is composed of water, bentonite and additives in addition to cement.

  Soil cement continuous wall was made by excavating soil with hardened material such as cement milk during excavation with a construction machine such as a multi-axis auger. A column pile wall is constructed.

  As shown in FIG. 1, the construction machine such as a multi-axis auger has a drilling head 4 as a tip of a screw drilling shaft that is rotationally driven by a driving device such as a hydraulic motor, and the cement passing through the inside of the screw drilling shaft 3. A hardening material such as milk can be poured from the drilling head.

  The drive device 2 is suspended from the leader mast of the base machine so as to be able to be lifted and lowered, and the screw excavation shaft 3 can be appropriately extended to be long. Further, the screw excavation shaft may not be a continuous screw but a discontinuous one with a stirring blade.

  The auger is positioned, and the drilling head of the auger screw drilling shaft is rotated forward to start drilling. At that time, the hardening liquid is taken out from the excavation head and injected into the hole.

  The present invention does not perform advanced excavation, and is divided into two parts (from the start to the end of the drilling and to the end of the end of the drilling until the completion of the pulling (two passes), and the water / cement ratio of the hardened material such as cement milk to be poured ( (W / C ratio) is changed. A soil removal section as shown in FIGS. 1 to 7 is not provided, and the soil removal section + injection section is set to a predetermined depth to be reached.

  From the start of drilling until reaching the specified depth, cement milk of poor blending [low weight ratio of water to cement-based solidification material (W / C ratio) is low] is injected, and when it is pulled up, rich blending [water for cement-based solidification material] The weight ratio (W / C ratio) is high] while the cement milk is being poured and turned.

  The rich blended cement milk is charged with a cement-based solidifying material in an amount that compensates for the lack of cement-based solidified material relative to the poor blended cement milk.

  Incidentally, the water / cement ratio (W / C ratio) of poorly blended cement milk is about 600%.

  In this way, even when the quality is hard, the excavation is performed by injecting cement milk with poor blending (low weight ratio of water to cement-based solidified material (W / C ratio) is low) from the start to the end of drilling. Without slowing down the drilling speed, there is no significant mud volume and cement milk increase.

The following shows examples of the present invention.
[Wall specifications]
φ850 34m Leading element Drilling section: 1.49425m ²
[One pass construction]
Setting the injection section length Cement 200kg
Bentonite 20kg
Additive (Emax-7) 10kg
400kg of water (W / C: 200%)
Total injection volume
Qt = 200 / 3.04 + 20 / 2.6 + 10 / 2.1 + 200 × (200/100) = 478.2L
Injection section length
Lq = 34.0 / (1+ (478.2 / 1000)) = 23.0m

Amount of injected material used Cement 1.49425 × 23.0 × 200 = 6873.6kg
Bentonite 1.49425 × 23.0 × 20 = 687.4kg
Additive (Emax-7) 1.49425 × 23.0 × 10 = 343.7kg
Water 1.49425 × 23.0 × 400 = 13747.1kg
Qt = 6873.6 / 3.04 + 687.4 / 2.6 + 343.7 / 2.1 + 13747.1 = 16436.2L

[2-pass construction]
(1) The drilling start position to the planned depth reaching was as follows.
Injection formulation (per injection target soil 1 m ³⁾
50kg cement
Bentonite 15kg
Additive (Emax-7) 0kg
Water 250kg (W / C: 500%)

Injection volume Q1 = 50 / 3.04 + 15 / 2.6 +50 x (500/100) = 272.2L

Amount of injected material Cement 1.49425 × 23.0 × 50 = 1718.4kg
Bentonite 1.49425 × 23.0 × 15 = 515.5kg
Additive (Emax-7) = 0.0kg
Water 1.49425 × 23.0 × 250 ＝ 8591.9kg
Qt = 1718.4 / 3.04 + 515.5 / 2.6 + 8591.9 = 9355.4L

(2) The process from reaching the planned depth to the drilling start position was as follows.
Injection formulation (per injection target soil 1 m ³⁾
150kg cement
Bentonite 5kg
Additive (Emax-7) 10kg
150kg of water (W / C: 100%)

Injection volume Q2 = 150 / 3.04 + 5 / 2.6 10 / 2.1 +150 x (100/100) = 206.0L

Injection material consumption Cement 1.49425 × 23.0 × 150 = 5155.2kg
Bentonite 1.49425 × 23.0 × 5 = 171.8kg
Additive (Emax-7) 1.49425 × 23.0 × 10 = 343.7kg
Water 1.49425 × 23.0 × 150 = 5155.2kg
Qt = 5155.2 / 3.04 + 171.8 / 2.6 + 343.7 / 2.1 + 5155.2 = 7080.7L

The comparison between the two is shown in the table below.
[table 1]
Injection material usage (total injection)

It is 1st process explanatory drawing which shows one Embodiment of the construction method of the soil cement pile as a prior art example. It is 2nd process explanatory drawing which shows one Embodiment of the construction method of the soil cement pile as a prior art example. It is 3rd process explanatory drawing which shows one Embodiment of the construction method of the soil cement pile as a prior art example. It is 4th process explanatory drawing which shows one Embodiment of the construction method of the soil cement pile as a prior art example. It is 5th process explanatory drawing which shows one Embodiment of the construction method of the soil cement pile as a prior art example. It is 6th process explanatory drawing which shows one Embodiment of the construction method of the soil cement pile as a prior art example. It is 7th process explanatory drawing which shows one Embodiment of the construction method of the soil cement pile as a prior art example. It is a schematic diagram of the construction method of the soil cement pile as a prior art example.

DESCRIPTION OF SYMBOLS 1 ... Auger 2 ... Drive apparatus 3 ... Excavation shaft 4 ... Excavation head 5 ... Hardening material 6 ... Leading excavation hole 7 ... Leader mast 8 ... Base machine 9 ... Kneading material 10 ... Soil 11a, 11b ... Hardening material penetration part 12 ... Air

Claims (2)

Target earth 1m ³ per cement weight required formulation eventually Zokabe eligible soil 1m per ³ cement amount to be added to the cement milk poor formulation to be injected into the original position soil from drilling start to plan the depth reached 25% or less and water cement ratio (W / C ratio) is 600% or less. When pulling up the screw from the planned depth to the drilling start position, each material of cement milk injected from the drilling start to the planned depth reached The soil cement continuous wall construction method is characterized by injecting as a rich blended cement milk the amount subtracted from all the additives required for building walls.   2. The method for constructing a soil cement continuous wall according to claim 1, wherein the wall is pulled up while turning to ensure kneading performance.

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