JPH07109727A - Deep mixing processing method and equipment - Google Patents

Abstract

(57) [Summary] [Structure] Since the cement slurry is mixed and stirred in the ground to solidify it, the mixing amount of the cement slurry into the ground, the concentration of the cement slurry, the amount of the water retaining material added to the cement slurry, the cement slurry At least one of the added amount of the filler and the added amount of the separation preventing agent to the cement slurry is adjusted according to the soil quality of each layer of the ground. [Effect] It is possible to prevent layers that are too strong as in the method of mixing a certain amount of cement slurry from being generated in the ground and affecting subsequent processes, so that the ground is composed of multiple layers with different soil types. Even if it is, it is possible to give proper strength to each layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cement-based deep layer mixing treatment method and apparatus suitable for use when the ground is composed of a plurality of strata having different soil properties.

[0002]

2. Description of the Related Art A type of consolidation method among ground improvement methods,
The cement-based deep-layer mixing treatment method that mixes and stirs cement slurry as a stabilizer in the ground and solidifies it is conventionally
When the ground consists of a sandy soil layer with different soil types and a cohesive soil layer, etc., focus on the viscous soil layer, which is the main symmetry for soil improvement, and mix the amount of cement slurry into the soil, Construction is performed with the concentration determined.

[0003]

As described above, when the cement slurry is set according to the cohesive soil layer, a large amount of cement is added to the surface buried soil portion and the sand layer portion alternating with the cohesive soil layer. As a result, the strength of these layers becomes too high, and there is a problem in that the subsequent steps such as a great amount of labor are required for subsequent excavation work and the like. This is mainly due to the following factors. Usually, the minimum injection amount of cement slurry is set to 100 liters / m ^3, and if it is set to less than this, the amount of slurry with respect to the soil of the ground is too small to perform uniform mixing and stirring, and the quality becomes unstable. For this reason, too much cement slurry is injected into the sand ground (sandy soil layer or surface soil). Here, the sandy soil layer, etc., has a small amount of clay minerals and organic components that inhibit the strength development as well as making cement slurry and mortar, and the water easily escapes from the cement slurry due to the dehydration phenomenon, leaving cement particles as water. Since the mixing ratio (W / C ratio) between the cement particles and the cement particles changes, if the injection amount of the cement slurry is too large, the strength will be too high. Also, if the cement slurry concentration is set low and pressure-fed for a long time, the flow path may be clogged due to the separation of cement particles and water, so the concentration cannot be set low and the W / C ratio is It will be set to 60 to 120% (usually 100% is the limit), and this will result in too much strength of the sandy soil layer and the like.

Therefore, with the same amount of addition, the strength of the cement is less than half that of ordinary cement (to obtain the same strength, use twice or more of the cement slurry). Although it was considered from the beginning to construct a low-strength slurry containing a water retaining / expanding material such as bentonite for construction, the following problems occur. Excessive strength can be suppressed in sandy soil layers, etc., but in cohesive soil layers the amount of cement slurry injected into the ground is large, causing problems such as lateral displacement of the ground and increase in lateral pressure around the construction site. there is a possibility. Originally, the main target of the deep layer mixing treatment is the cohesive soil layer, and therefore, the target soil is usually more clayey soil layer than sandy soil layer. Therefore, the above method may cause a problem due to lateral displacement, etc., as compared with the case where the water retaining / extending material and water are added only to the sandy soil layer. The water retaining / extending material is used even in an originally unnecessary portion, which results in a significant cost increase.

Therefore, the object of the present invention is to provide appropriate strength to each layer even if the ground is composed of a plurality of layers with different soil properties, and it does not hinder the subsequent process. It is an object of the present invention to provide a deep mixing processing method and apparatus.

[0006]

To achieve the above object, the deep layer mixing treatment method of the present invention is a cement-based construction method in which cement slurry is mixed and stirred in the ground to solidify, and the ground of the cement slurry is used. At least one of the mixing amount of the cement slurry, the concentration of the cement slurry, the addition amount of the water retaining material to the cement slurry, the addition amount of the extender material to the cement slurry and the addition amount of the separation preventing agent to the cement slurry, The feature is that it is adjusted according to the soil quality of each layer of the ground.

Further, the deep layer mixing treatment apparatus of the present invention comprises a storage means for storing the cement slurry, a pressure pump for pumping the cement slurry from the storage means, a cement inserted into the ground and pumped by the pressure pump. A mixing and stirring means for stirring the slurry while mixing it with the ground, and a mixing means for mixing at least one of water, a water retention material, a filler and a separation preventing agent into the cement slurry to be pressure-fed. It is characterized by that.

[0008]

According to the deep mixing treatment method of the present invention, the amount of cement slurry mixed into the ground, the concentration of the cement slurry, the amount of the water retention material added to the cement slurry, and the cement, depending on the soil quality of each layer of the ground Since at least one of the amount of the filler added to the slurry and the amount of the separation inhibitor added to the cement slurry will be adjusted, as in the method of mixing a certain amount of cement slurry with the ground. It is possible to prevent the formation of a layer having too high strength.

According to the deep mixture processing apparatus of the present invention, water,
Since a mixing means for mixing at least one of the water retaining material, the extending material and the separation preventing agent into the cement slurry pressure-fed by the pressure-feeding pump is provided, each mixing layer allows each layer of the ground to be mixed. Depending on the soil quality, the amount of cement slurry mixed into the ground, the concentration of cement slurry,
This adjusted cement slurry is adjusted by adjusting at least one of the amount of the water retention material added to the cement slurry, the amount of the extender added to the cement slurry, and the amount of the separation inhibitor added to the cement slurry. Can be stirred while being mixed with the ground by the mixing and stirring means.
Therefore, as in the method of mixing a certain amount of cement slurry into the ground, a layer with too much strength is generated,
Can be prevented.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A deep layer mixing processing method and apparatus according to a first embodiment of the present invention will be described below with reference to the drawings. First of all
The deep layer mixing processing apparatus of the embodiment will be described with reference to FIGS. Reference numeral 1 in FIG. 1 indicates a storage means for storing the cement slurry. The storage means 1 includes a cement silo 2 for storing cement and a cement silo 2 for storing the cement slurry.
A hopper 3 for receiving the cement sent out from the hopper 3, a water storage section 4 for storing water, a cement measuring section 6 for metering the cement from the hopper 3 into a slurry mixer 5 described below in predetermined amounts, and a water storage section 4 A water metering unit 7 for measuring a predetermined amount of water and injecting it into a slurry mixer 5 described later by a predetermined amount, a slurry mixer 5 for mixing the injected water and cement to form a cement slurry, and separating the cement slurry into materials. Agitator 8 stirred to prevent it
And have.

The agitator 8 is connected to one end sides of main hoses 10 of two systems according to the number of stirring shafts 16 to be described later.
A pump 11 for pumping the cement slurry from is provided adjacent to the agitator 8. Here, the pressure feed pump 11 is connected to a control device 12 (see FIG. 2) described later, and a signal from the control device 12 controls the discharge amount per unit time to drive the pump. There is.

The other end of the main hose 10 is connected to a stirrer 14 provided on the crawler crane 13 so as to be movable at least in the vertical direction.
4 is moved up and down by a lift drive mechanism 15 (see FIG. 2) driven by a signal from the control device 12. The stirring device 14 has a plurality of stirring shafts 16 that are hollow and extend in the vertical direction. At the lower end of these stirring shafts 16, a stirring blade 17 for mixing and stirring is attached so as to rotate integrally. ing. The stirring shaft 16 is adapted to be driven to rotate about an axis by a rotary drive mechanism 18 (see FIG. 2) driven by a signal from the control device 12, and the stirring shaft 16 and the stirring blade 17 A mixing and stirring means 19 is configured to stir the cement slurry while mixing it with the ground. Here, the cement slurry pressure-fed by the pressure-feed pump 11 via the main hose 10 is the above-mentioned stirring shaft 1
After passing through the inside of 6 to reach the inside of the stirring blade 17, the stirring blade 17 or the stirring shaft 16 is jetted to the outside from a jet hole (not shown) provided in the stirring shaft 16.

Then, in the first embodiment, the stirring device 1
A mixing means 21 for selectively mixing water and bentonite muddy water into the cement slurry to be pressure-fed is connected to the main hose 10 between the pressure hose 4 and the pressure-feed pump 11. The mixing means 21 will be described below. The mixing means 21 includes a water tank 22 for storing water, a water hose 23 having one end connected to the water tank 22, a mud tank 24 for storing bentonite mud, and one end connected to the mud tank 24. The hose 25 for muddy water is provided, and the static mixer 27 is provided in the vicinity of the stirring device 14 of the main hose 10, and the other ends of the hose 23 for water and the hose 25 for muddy water are connected.

Then, the water tank 2 of the water hose 23
A water pump 28 that pumps water from the water tank 22 toward the static mixer 27 is provided near the connection position with the water tank 2. The water hose between the water pump 28 and the static mixer 27 is provided. A water check valve 29 for preventing backflow from the static mixer 27 to the water pump 28 side is provided at 23. Similarly, hose 25 for muddy water
A muddy water pump 30 that pumps bentonite muddy water from the muddy water tank 24 toward the static mixer 27 is provided near the connection position with the muddy water tank 24. The muddy water pump 30 and the static mixer 27 A muddy water check valve 31 that prevents a reverse flow from the static mixer 27 to the muddy water pump 30 side is provided in the muddy water hose 25 between. The water pump 28 and the muddy water pump 30 are driven by controlling the discharge amount per unit time by a signal from the control device 12.

As shown in FIG. 3, the static mixer 27 is a mixing element in which an element 35 and an element 36 shown in FIG. 4 are alternately arranged inside a mixer portion 34 at a predetermined intermediate position of a tubular housing 33. 37 is fixed, the port 38 is on the side of the pressure pump 11 of the main hose 10, the port 39 is on the side of the stirring device 14 of the main hose 10, the port 40 is on the water hose 23, and the port 41 is on the mud hose 25. Respectively connected to.
The mixing element 37 is then connected to the ports 38, 40, 4
The outer side and the housing 3 from the 1 side toward the port 39 side
When a fluid passes between the fluids 3 and 3, the flow is divided or the flow direction is reversed so that the fluids are mixed so as to be in a uniform state. Here, the static mixer 27 can be provided in any place between the stirring shaft 16 and the pressure feed pump 11. The static mixer 27 is installed so that the position of the port 39 on the outlet side is horizontal or higher than the position of the port 38 on the inlet side.

In the first embodiment, bentonite muddy water is used as the water containing the water for adjusting the concentration of the cement slurry, the water retaining material, the extender and the separation preventing agent. That is, the bentonite muddy water changes the W / C ratio of the cement slurry depending on its water content, and the bentonite (clay content) contained therein is added to the cement slurry to increase the components other than cement. Strength at the time of hardening decreases (action as a filler)
At the same time, it prevents the strength from increasing due to the escape of water to the outside (acts as a water retaining material), and further prevents the cement from separating and settling in the main hose 10 and the like (separation preventing material). Action).

In the first embodiment, the stirring device 14 is provided with a depth meter (see FIG. 2) 42 for detecting the depth of the stirring blade 17 and outputting a signal indicating the depth to the control device 12. There is. In addition, the control device 12 has a pressure feed pump 11 for obtaining the data of the depth of each layer of the ground previously checked and the cement slurry most suitable for the layer at each depth.
The discharge amount and drive time per unit time of the water pump 28 and the muddy water pump 30 are stored,
The control device 12 receives a signal from the depth gauge 42 and outputs a predetermined signal to a predetermined one of the pressure pump 11, the water pump 28, and the muddy water pump 30.

For example, if there is a sandy soil layer at a certain depth close to the surface, the controller 12 does not give too much strength when a signal indicating the depth corresponding to this sandy soil layer is received from the depth meter 42. Pressure pump 11 and muddy water pump 30 in order to mix the cement slurry having a low concentration and containing a water retention material, a filler and a separation preventing agent with the sandy soil layer,
A signal is output to each of them so as to drive for a time corresponding to the amount of soil with a discharge amount corresponding to the soil type of the sandy soil layer. That is, for example, when the clay content of the sandy soil layer is extremely low and it is desired to increase the mixing ratio of bentonite mud to cement slurry, the discharge amount of bentonite mud per unit time relative to the discharge amount of cement slurry per unit time You can increase the ratio. As a result, the cement slurry pumped by the pump 11 is mixed with the bentonite muddy water pumped by the muddy water pump 30 at a ratio matched with the soil by the static mixer 27, and then sprayed from the stirring blade 17 to the sandy soil layer. With this ejection, the control device 1
2 outputs a signal to the rotation drive mechanism 18 to rotate the stirring shaft 16 and the stirring blade 17 to perform mixing and stirring.
When the mixing and stirring of the cement slurry in the sandy soil layer is completed, the control device 12 outputs a signal to the lifting drive mechanism 15 to drive the lifting drive mechanism 15 to lower the stirring device 14, that is, the stirring blade 17. If the layer at this depth is, for example, an intermediate soil layer having an intermediate property between the cohesive soil layer and the sandy soil layer, the depth meter 4 outputs a signal indicating the depth corresponding to this intermediate soil layer.
When receiving from 2, the control device 12 controls the pumping pump 11 and the water pump 28 to mix the cement slurry having a low concentration for a time corresponding to the amount of soil with a discharge amount that matches the soil type of the intermediate soil layer. Output signals to them to drive. As a result, after the cement slurry pumped by the pump 11 is mixed with the water pumped by the water pump 28 in the static mixer 27 at a ratio according to the soil quality,
It will be jetted from the stirring blade 17 to the intermediate soil layer, and the stirring blade 17 will perform mixing and stirring together with this jetting. When the mixing and stirring of the cement slurry into the intermediate soil layer is completed, the control device 12 outputs a signal to the elevating drive mechanism 15 to drive the elevating drive mechanism 15 to lower the stirring blades 17, and the layer of this depth , For example, if it is a cohesive soil layer,
When a signal indicating the depth corresponding to this cohesive soil layer is received from the depth meter 42, in order to mix the cement slurry having a high concentration so as to obtain strength, the pressure-feed pump 11 of the cohesive soil layer is mixed. A signal is output to this so that it will be driven for a time that matches the volume of soil. As a result, the cement slurry pressure-fed by the pressure-feeding pump 11 passes through the static mixer 27 as it is and is jetted from the stirring blade 17 to the viscous soil layer, and together with this jetting, the stirring blade 17 carries out mixing and stirring.

According to the deep layer mixing processing apparatus having such a structure and the deep layer mixing processing method using the same, the pressure feed pump 1
The cement slurry pressure-fed at 1 is provided with the mixing means 21 for mixing water or bentonite muddy water, so that the mixing means 21 allows the concentration of the cement slurry and the cement to be mixed depending on the soil quality of each layer of the ground. The amount of bentonite added to the slurry is adjusted, and the adjusted cement slurry is mixed and stirred by a required mixing amount 19
It is possible to stir it while mixing it with the ground by the stirring blade 17 of. Therefore, it is possible to prevent the formation of a layer having too high strength as in the method of mixing a certain amount of cement slurry with the ground. Therefore, even when the ground is composed of a plurality of strata having different soil properties, appropriate strength can be imparted to each stratum, and the post-process such as excavation is not hindered.

Moreover, as described above, the control device 12 receives the signal from the depth gauge 42 and outputs the signal to the necessary one of the pressure pump 11, the water pump 28 and the muddy water pump 30. Optimal cement slurries can be automatically mixed into the layers at each depth investigated beforehand.

Even if the mixing and stirring of the cement slurry and the ground are performed while the stirring blade 17 of the stirring device 14 moves from the upper side to the lower side, the stirring blade 17 is once rotated down to the lowest stratum. After that, it may be performed while the stirring blade 17 moves from the bottom to the top. Further, in any of the above cases, the stirring blade may be continuously rotated in the vertical direction while being continuously rotated, or either the rotation or the vertical movement may be intermittently performed as necessary.

Further, as in the first embodiment, the controller 12 automatically controls the pressure pump 11, the water pump 28 and the muddy water pump 30 according to the soil quality of each layer of the ground by the signal from the depth gauge. Although it is configured to be selectively driven on the basis of the data, the depth data by the depth meter 42 is displayed, and the operator can follow the display to display the depth data.
1, the water pump 28 and the muddy water pump 30 may be selectively driven based on the data according to the soil quality of each layer of the ground.

Further, without providing the depth gauge 42, by providing a torque meter for detecting the stirring torque of the stirring blade 17 and outputting a signal indicating the stirring torque to the control device 12, the control device 12 detects it. Which soil and hardness the agitated torque corresponds to agitated is compared with prestored data to make a determination, and the pressure pump 11, the water pump 28 and the muddy water pump 30 are selected according to the soil quality. It is also possible to drive selectively. In this case, of course, if the stirring torque is large, it is judged as a hard sandy soil layer, and if the stirring torque is small, it is judged as a soft cohesive soil layer. The penetration resistance to the ground of the penetration cone attached near the stirring blade 17 may be detected instead of the stirring blade 17.

It is also possible to directly inject the bentonite mud into the soil layer and stir it with the stirring blades 17 without mixing the bentonite mud etc. into the cement slurry under pressure feeding. W / C ratio is 1
While the specific gravity of the 00% cement slurry is about 1.5, the bentonite muddy water has a viscosity of about 1.06 and a high viscosity, so both are difficult to mix. Therefore, as described above, it is preferable to mix bentonite muddy water or the like directly into the cement slurry being pumped and homogenize it as a slurry before injecting it into the ground. Further, since the static mixer 27 can mix bentonite muddy water and the like into the cement slurry uniformly without moving itself, it is easy to handle and highly safe. Here, on-shore deep mixing processing equipment,
When using the static mixer 27, one is required for each system of cement slurry piping, but the diameter is 1.5
A small one with a length of up to 3 inches and a length of about 1 m is sufficient, and installation and handling are easy.

In addition, in the above-mentioned first embodiment, the bentonite mud was used as the water containing the water for adjusting the concentration of the cement slurry, the water retaining material, the extender and the separation preventing agent, but these were separately prepared. Of course, it is also possible to store and introduce each into a static mixer by a pump or the like, and if configured in this way, the characteristics of the cement slurry can be adjusted more finely.

Furthermore, depending on the soil quality of each layer of the ground,
A plurality of types of cement slurries in which at least one of the concentration, the addition amount of the water retention material, the addition amount of the extender material and the addition amount of the separation preventing agent is adjusted are individually stored in advance in the storage means, and It is also possible to provide connection switching means such as an electromagnetic valve for connecting any one of them to the mixing and stirring means depending on the soil quality.

Next, a deep layer mixing processing apparatus according to the second embodiment of the present invention will be described below with reference to FIG. 5, focusing on the differences from the first embodiment. The same parts as those in the first embodiment are designated by the same reference numerals and the description thereof is omitted.

In the second embodiment, one main hose 10 on the side connected to the agitator 8 is provided, and this one main hose 10 is provided with a pressure pump 11 and a static mixer 27 having a capacity for two systems of slurry. ing. Then, in the static mixer 27, one system of the water tank 22, the water hose 23, the water pump 28, and the water check valve 29, the muddy water tank 24, the muddy water hose 25, the muddy water pump 30, and the muddy water are provided. It is connected to one system of the check valve 31 for use.

The main hose 10 on the downstream side of the static mixer 27 is divided into two pieces, and the divided main hoses 10 are each provided with a stirring shaft 16 and the like as in the first embodiment, and are divided. Main hose 10
The main pressure pumps 50 are provided near the respective divided positions.

According to the second embodiment having such a structure, it is possible to obtain the same effect as that of the first embodiment, and of course, the first embodiment has a slurry pressure feeding system after the agitator 8 with one stirring shaft. In contrast to the configuration having one for every 16 units, the second embodiment shares the slurry pressure feeding system from the agitator 8 to the static mixer 27, so that the addition system of water and bentonite mud is as described above. It can be a system (that is, the mixing means 21 can be a system).

Therefore, if a small buffer tank or the like is installed immediately in front of the main pressure pump 50, the quality confirmation and check of the slurry after the admixture of the additive and the like can be directly and simply performed (first embodiment). In the case of, the check is performed on the calculated value from the addition flow rate and the flow rate of the raw slurry based on the blending calculation, and the static mixer
Since there are two, it is necessary to check two systems). In addition, since only one route for mixing the additive and the like into the raw slurry is required, the control / management operation becomes easy. Further, since the mixing route of the additive material and the like is small and simplified, maintenance, cleaning and the like become easy.

[0032]

As described above in detail, according to the deep layer mixing treatment method and apparatus of the present invention, it is possible to prevent the formation of a layer having too high strength as in the method of mixing a certain cement slurry into the ground. Since it can be prevented, even when the ground is composed of a plurality of strata having different soil properties, proper strength can be given to each stratum, and there is no hindrance to a post-process such as excavation.

[Brief description of drawings]

FIG. 1 is a front view showing the overall configuration of a deep layer mixing processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a control system of the deep layer mixing processing apparatus according to the first embodiment of the present invention.

FIG. 3 is a sectional view schematically showing a static mixer of the deep layer mixing processing apparatus according to the first embodiment of the present invention.

FIG. 4 is a plan view showing a mixing element of the static mixer of the deep layer mixing processing apparatus according to the first embodiment of the present invention.

FIG. 5 is a front view showing the overall configuration of a deep layer mixing processing apparatus according to the second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Storage means 11 Pressure feed pump 19 Mixing and stirring means 21 Mixing means

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Sumio Horiuchi 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Juichi Ise 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Takanori Hirai 1-3-2 Shibaura, Minato-ku, Tokyo Shimizu Construction Co., Ltd.

Claims (2)

[Claims] 1. A cement-based deep layer mixing treatment method in which cement slurry is mixed and stirred in the ground to be solidified, wherein the amount of cement slurry mixed into the ground, the concentration of the cement slurry, and the addition of a water retention material to the cement slurry. At least one of the amount, the amount of the filler added to the cement slurry, and the amount of the separation inhibitor added to the cement slurry is adjusted according to the soil quality of each layer of the ground. Mixed processing method. 2. A storage means for storing the cement slurry, a pressure pump for pumping the cement slurry from the storage means, a cement slurry inserted into the ground and mixed with the cement slurry pumped by the pressure pump while stirring the ground. An apparatus for deep-layer mixing, comprising mixing and stirring means and mixing means for mixing at least one of water, a water retaining material, a bulking material, and a separation preventing agent into the cement slurry to be pumped. .