JP2012041794A - Ground improvement method and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which a method of generating vortex flow and cavitation by installing conventional nozzles in close proximity to each other and causing mutual interference of jet flows in close proximity to each other causes shake of a rod during construction due to deviation of load because of high pressure injection of two nozzles in the same direction and homogeneity of a constructed hardening material injection layer is problematic.SOLUTION: A pair of multi-injection nozzles oppositely facing with a vertical step difference or injection rods set to be a pair or plural pairs are inserted into an object ground, and a hardening material is injected from an upper stage nozzle at high pressure. At the sama time, the hardening material is injected from a lower stage nozzle at high pressure by a discharge amount one to two times as much as that injected from the upper stage nozzle to construct a hardening material injected layer.

Description

  TECHNICAL FIELD The present invention relates to a ground improvement method and an apparatus therefor, in which a ground hardening material is injected into a target ground by high-pressure injection into a target ground for the purpose of strengthening support of a built foundation ground or stabilizing the ground and stopping water. Is.

  Conventionally, for ground lining material injection for ground lining support and reinforcement support, or for hardening material layer construction for water stoppage, injection rod while injecting ground hardening material from injection rod inserted into target ground with high pressure In order to create a hardened material layer with a large diameter by extending the reach of the hardened material jet as much as possible, various methods have been used. Ingenuity has been elaborated.

  As a means for extending the reach of the curable material jet, a method for extending the reach by encapsulating the curable material jet with air using a polymerization injection nozzle comprising a core nozzle and an annular nozzle surrounding the core nozzle (for example, Patent Document 1) Have been developed). This superposition jet nozzle is used not only for the injection and injection of ground hardening material, but also for the case of performing fresh water injection for excavation of the ground or mixing and stirring.

  In addition, development aimed at increasing the injection pressure and increasing the discharge amount of the hardened material is being promoted in order to increase the diameter of the formed hardened material layer and speed up the injection work. As a means for increasing the crushing force of the hardening material jet itself, there is a method of making a cycloid jet (for example, see Patent Document 2) and a method for making a cavitation jet by jet impact (for example, see Patent Document 3). Proposed.

Further, as described in Patent Document 4, a second nozzle is provided in the vicinity of the lower portion of the first nozzle provided on the tip side wall of the injection rod, and the hardening material is provided in the same direction from the material liquid injection nozzle provided in each nozzle. Proposals have been made to increase the jet action area in the ground by vortexing and cavitation generated by jetting the liquid at high pressure and jetting jetted from each of the first nozzle and the second nozzle.
Japanese Examined Patent Publication No. 7-100931 JP-A-57-66219 JP 2001-295263 A JP 2008-69549 A

  However, the cycloid jet and the cavity jet according to Patent Documents 2 and 3 are jetted after being generated in the injection rod, and a direct effect as it is cannot be expected. In addition, the method in which nozzles are set close to each other and vortex and cavitation are generated by mutual interference between the adjacent jets is jetted in the same direction from the two nozzles. In addition, there remains a problem with the homogeneity of the hardened material injection layer.

  Therefore, the invention of the present application maintains the balance by setting the back of the polymerization injection nozzle that protects the curable material jet by enclosing it with air and extends the reach distance, and at two nozzle setting positions. Although a step of about 8 cm is provided, there is a problem that the air-enclosed jet that faces backward diffuses and remains at the tip and interferes with the jet flow from the rotating lower polymerization jet nozzle to attenuate the jet energy.

  The jet flow diameter of the jet jet when the hardened material is jetted at a high pressure is usually about 5 to 10 cm at a position about 1.5 m away from the injection nozzle, and the flow diameter increases as the distance from the nozzle increases. The improvement diameter of the improved body is determined by the amount of injection energy, and even if it is injected many times at the same position, the drilling diameter will not be expanded and the improved body quality will be greatly improved even if it is about 3 times or more. It is said that multiple injections that are polymerized increase the amount of waste treatment due to the loss of the amount of hardener used and the increase in the amount of sludge, leading to an increase in the environmental burden.

  In addition, the present invention is intended to extend the reach of the hardener jet flow by the crushing energy of the cavitation generated at the difference interface by providing a difference in the amount of the hardener discharged from the polymerization injection nozzle that is set to the back and provided with a step. However, the multiple injections that polymerize as described above have the problem of increasing the amount of waste treatment due to the loss of the amount of hardener used and the increase in the amount of sludge, and excess slime due to the use of air and adjustment of the amount of hardener discharged There is a problem that must be discharged.

  In order to solve the above-mentioned problems, the present invention is a superposition jet comprising a core nozzle and a surrounding nozzle, which forms a pair with a step of about 2 to 8 cm on the side wall of the tip of the injection rod. One or more pairs of injection rods set in the nozzle are inserted into the target ground, and while blowing air from the surrounding nozzles of each polymerization injection nozzle, the curing material is injected at high pressure from the core nozzle of the upper polymerization injection nozzle of the pair, At the same time, the injection rod is rotated and raised while high-pressure injection of a hardened material with a discharge amount 1 to 2 times that of the hardened material injected from the core nozzle of the upper polymerization injection nozzle from the core nozzle of the lower polymerization injection nozzle. And a hardener injection layer was constructed.

  In other words, the polymerization jet nozzle that encloses and protects the curable material jet with air and extends the reach distance is maintained, and the balance is maintained by setting the back of the nozzle, and the nozzle setting position is about 2 to 8 cm. In addition to being configured to provide a level difference, the curing material is injected at high pressure from the core nozzle of the upper polymerization injection nozzle, and at the same time, injected from the core nozzle of the lower polymerization injection nozzle paired with the core nozzle of the upper polymerization injection nozzle. The curing material injection layer was formed by rotating and raising the injection rod while high-pressure jetting the curing material with a discharge amount 1 to 2 times that of the curing material.

  In order to verify the effective use of jet energy by high-pressure injection, the applicant has conducted a hard material layer formation experiment in the ground for proportional injection that makes a difference in the discharge amount of the upper and lower injection nozzles. According to this experiment, when the pump discharge rate was 400 liters / minute, in the case where the nozzles A and B were injected at the same discharge rate of 200 liters / minute, the formed diameter was 4.6 meters. In the case of jetting at a discharge rate of 160 liters / minute for the A nozzle and 240 liters / minute for the B nozzle, a formed diameter of 5.0 meters is obtained.

  As a result, it is possible to effectively use high-pressure injection energy by changing the injection amount of the hardener from the nozzle set backward by shifting the vertical position, primary cutting (preceding cutting) and secondary cutting (partition cutting) Thus, it was confirmed that the diameter of the ground improvement layer can be expanded.

この効果を用いれば、異なる地盤強度の地盤における造成を同じ噴射時間で行うことも可能にする。従来工法では、地盤強度が大きくなった場合には、噴射時間を長くすることで同一の造成径を得る設計が行われているが、全体の噴射量を変えずに上下位置をずらして背向設定したノズルよりの硬化材噴射量を変化させることにより、同じ噴射時間で同一の造成径を得ることがてきる。 Furthermore, from the compression test results in the following table of the specimens cored from the improved body, no reduction in strength was observed near the outer periphery of the improved body, and it was confirmed that sufficient stirring and mixing were performed.

If this effect is used, it becomes possible to perform the creation on the ground having different ground strengths in the same injection time. In the conventional construction method, when the ground strength is increased, the same formation diameter is obtained by increasing the injection time, but the vertical position is shifted without changing the overall injection amount. By changing the injection amount of the curing material from the set nozzle, the same formed diameter can be obtained in the same injection time.

  For example, (a) sandy soil with an N value of 0 to 30 and a discharge ratio of A to B of 1: 1, and (b) discharge of A to B with sandy soil with an N value of 30 to 50. Amount ratio of 1 to 1.5, (c) Sandy soil with N value of 50 to 100, A to B discharge rate ratio of 1 to 2, (d) Adhesive strength C from 0 to 50 kilonewtons The ratio of A to B discharge rate is 1 to 1 for viscous soil up to 1 / square meter, and (e) 1 to 1 ratio of A to B discharge rate for viscous soil with adhesive strength C of 50 to 100 kilonewtons / square meter. 1.5, (f) The ratio of the discharge amount of A to B is set to 1 to 2 in the viscous soil having an adhesive strength C of 100 kilonewtons / square meter or more.

  FIG. 8 shows a nozzle in which the total discharge amount of the two nozzles set in the back direction is set to the same amount in the above experiment, and the nozzle set in the back direction without shifting the vertical position and the part where the vertical position is shifted and the level difference is provided. The change in jet arrival distance when the secondary cutting (partition cutting) is performed after the primary cutting (preceding cutting) is performed by the jet flow from the nozzle set backward, and the discharge amount of the secondary cutting nozzle As a longitudinal side view comparing the shape of the jet trajectory that overlaps in the upper half or lower half when the discharge amount of the primary cutting nozzle is 1.5 times, and the jet trajectory radius part indicating the change in jet arrival distance, respectively. It is shown.

  (No. 1) of FIG. 7 shows that each nozzle 200 is subjected to a two-time cutting in which a preceding cutting is performed by a preceding nozzle at a step of 25 mm in a nozzle set backward with no step and a partition cutting is performed by a subsequent nozzle. The process of cutting twice for the same part in one rotation at a discharge rate of liters / minute (total 400 liters / minute) and stepping up by 25 mm is repeated four times.

  (No. 1) is the same nozzle as (No. 1), and discharge is 160 liters / minute for leading cutting by the preceding nozzle and 240 liters / minute for partition cutting by the trailing nozzle (total 400 liters / minute). FIG. 6 is a jet trajectory diagram in which a process of stepping up by 25 mm is performed four times by cutting twice for the same part in one rotation.

  (2-1) is a nozzle set with a step of about 25 mm and set to the back. After the preceding cutting is performed with the upper nozzle in one step 50 mm, the partition cutting is performed with the lower nozzle, and the cutting is performed twice. The process of stepping up by 50 mm is performed twice by cutting twice by shifting the vertical position of the same part in two revolutions at a discharge rate of 200 liters / minute for each nozzle (total 400 liters / minute).

  (No. 2) is the same as (No. 1). After the preceding cutting is performed with the upper nozzle in one step 50 mm by the nozzle set with a step of about 25 mm, the partition cutting with the lower nozzle is performed. Cutting is performed twice for the same part in two revolutions with a discharge rate of 160 liters / minute for the preceding nozzle and partition liters for the subsequent nozzle of 240 liters / minute (total 400 liters / minute). The process of stepping up by millimeters is repeated twice.

  Although the nozzle has no level difference, the discharge amount of the succeeding nozzle is 1.5 times that of the preceding nozzle (1-2), compared with (1-1), the reach distance of the partition cutting jet by the succeeding nozzle is clear Is extended. Furthermore, when the nozzles set with a step are set to the back and the discharge amount of the upper nozzle and the lower nozzle is the same amount (No. 1), there is no step (No. 1), which is substantially the same in the reach distance. When the discharge amount of the succeeding nozzle is 1.5 times that of the preceding nozzle (No. 2), the jet flow distance of the succeeding nozzle is clearly extended as compared with the other cases.

  From this, it can be confirmed that the reach of the curable material jet can be greatly extended by making the discharge amount of the lower nozzle 1.5 times that of the upper nozzle with the nozzle set to the back with a step. did it. In this way, the ground improvement method is based on the above-described injection by a pair of nozzles provided with a step difference in the vertical direction.

  Also, in response to the problem that the air-enclosed jet facing backward diffuses and remains at the tip and interferes with the jet flow from the rotating lower polymerization injection nozzle to attenuate the injection energy, the outer periphery of the polymerization injection nozzle is A shielding plate is set along the axial direction of the outer peripheral wall of the injection rod between the overlapping injection nozzles surrounded by the cylindrical shield or adjacent to prevent the diffusion and interference of the jet flow injected from the polymerization injection nozzle. It was configured as follows.

  Furthermore, the range of the curing material discharge from the polymerization injection nozzle is set to extend the reach of the curing material jet by the cavitation crushing energy generated at the difference interface, but by using air and adjusting the amount of curing material discharged Corresponding to the inevitable occurrence of excessive slime, excavation and discharge projecting in the shape of an auger wing along the outer peripheral wall of the injection rod between adjacent superposition jet nozzles in order to actively discharge the excess slime The wings were set and configured to crush and lift the slime.

  According to the present invention, the above-described configuration dramatically extends the underground propulsion distance of the curing material jet by the polymerization jet nozzle as compared with the conventional one, and actively discharges excess slime generated by the use of air. As a result, it was possible to improve the efficiency and cost of improved construction by eliminating uplift on the ground in unexpected places and waste of spray material.

The side view of the injection rod front-end | tip part which shows the Example of this invention and shows the jet flow injected from the nozzle which set the back and set the step Similarly, a vertical cross-sectional side view of the tip of the injection rod showing the main part of the structure as a vertical cross-section of the injection rod set with a polymerization injection nozzle set to the back with a step Similarly, the side view of the front outer surface portion of the injection rod showing the positional relationship between the two pairs of superposition jet nozzles from the side when two pairs of superposition jet nozzles set to the back with steps are set. Similarly, the cross-sectional plan view of the injection rod tip nozzle setting portion showing the positional relationship between the two pairs of superposition jet nozzles in FIG. Similarly, a side view of the tip of the injection rod with a cylindrical shield and an auger blade set on a pair of superposition jet nozzles set back with steps Similarly, two pairs of superposition jet nozzles are set, a cylindrical shield is set for one pair, and a shield plate is set between each nozzle. The positional relationship between the nozzle of the injection rod, the cylindrical shield, and the shield plate is determined in the axial direction. Cross section plan view of injection rod tip nozzle setting part Similarly, a pair of superposition jet nozzles is set, a cylindrical shield is set for the nozzle, and the auger blade is set between the nozzles. Cross section plan view of injection rod tip nozzle setting section Similarly, it is a vertical side view of the jet trajectory radius portion schematically showing the jet trajectory by a jet experiment from a pair of superposition jet nozzles set in the back direction. (No. 1) is the lower nozzle discharge amount 1.5 times the upper nozzle discharge amount without the upper and lower steps, (No. 1) is the same amount of discharge amount with the upper and lower steps, (2-2) is a comparison of jet trajectories with a step difference between the lower nozzle and the upper nozzle discharge amount 1.5 times the upper nozzle discharge amount. Similarly, the construction situation diagram showing the entire device with the hardened material layer forming part as a longitudinal side view

  Embodiments of the present invention will be described below with reference to the drawings. Reference numeral 1 denotes an injection rod, which is an upper polymerization injection nozzle A (hereinafter referred to as an upper nozzle) consisting of a core nozzle 2 and a surrounding nozzle 21 on the flank, and a portion facing away from the nozzle A, about 2 to 8 cm below the nozzle A The lower polymerization injection nozzle B (hereinafter referred to as the lower nozzle), which is also composed of the core nozzle 2 and the surrounding nozzle 21, is paired with the nozzle A and has a bit 11 at the tip.

  The injection rod 1 is supported by a rotation mechanism 13 and a vertical movement mechanism 14 and is driven by an operation mechanism 15. A hardening material channel 3 having a core nozzle 2 as an opening and a surrounding nozzle are provided on a lower side of the injection rod 1. An air supply path 31 having an opening 21 is provided, and communicates with a curing material supply unit (not shown) and an air compressor (not shown) via the swivel 12.

  The core nozzle 2 is provided with a replaceable nozzle tip (not shown) so that the nozzle diameter can be adjusted according to the injection design, and the discharge amount of the curing material can be regulated by replacing the tip. Also, by inputting to the operation mechanism 15 how many millimeters one step is to be set and how many rotations are to be stepped up, the injection driving of the injection rod 1 in accordance with the injection design is automatically performed.

  The injection rod 1 configured as described above is rotated while supplying fresh water or the like as a lubricating liquid through the hardening material flow path 3 and ejected from the lower ejection hole 16, and is inserted into the target ground by the tip bit 11, and has a predetermined depth. At the same time, the lower injection hole 16 is closed by the ball valve 17, and fresh water or the like is switched to a hardening material, and high-pressure injection is performed from the core nozzle 2, and at the same time, air is injected from the surrounding nozzle 21 through the air supply path 31.

As described above, the hardener jet is jetted at high pressure as a jet encapsulated in air. As shown in FIG. 1, the set jet nozzle is a pair of nozzles set backward with a step of about 25 mm. In this process, the discharge amount of the lower nozzle is set to 240 liters / minute (total 400 liters / minute), which is 1.5 times that of the upper nozzle (160 liters / minute). It is designed to cut twice with two nozzles with no step, one step is 25 mm, work efficiency is better than construction with each nozzle 200 liters / minute (total 400 liters / minute), and the jet reaches The distance can also be extended.

  In the second embodiment, two pairs of nozzles which are set backward with a step of about 25 mm are used, and, as shown in FIGS. The second nozzle pair is set in a direction rotated 90 degrees below the step difference between the nozzles in the second stage to widen the direction of the jet and to two-dimensionally balance the energy. .

  That is, the second upper nozzle C is set at a distance of about 25 mm in the direction rotated 90 degrees from the lower nozzle B of the first-stage counter nozzle, and 25 of the second upper nozzle C is set. The second lower nozzle D that faces away from the nozzle C with an interval of about a millimeter downward is set.

  In this case, the discharge amount from nozzle A and nozzle C is 160 liters / minute, the discharge amount from nozzle B and nozzle D is 240 liters / minute, one step is 50 mm, and the process is performed in a step-up process with one rotation. As a result, efficient stirring and mixing in which the cutting jet is parallel to the first-stage nozzle and the second-stage nozzle is performed, and high-speed construction is possible.

  In Example 3, in response to the problem that the air-enclosed jet facing backward diffuses and remains at the tip and interferes with the jet flow from the lower polymerization jet nozzle that has rotated, the jet energy is attenuated. By surrounding the outer periphery with a cylindrical shield 4 and the height of the cylinder being about 15 mm, the jet flow attenuation at the nozzle opening is suppressed and the injection energy is concentrated in the propulsion direction.

The fourth embodiment corresponds to the problem that the adjacent air-encompassing jet diffuses and remains at the tip as in the third embodiment and interferes with the jet flow from the adjacent rotating nozzle to attenuate the jet energy. Therefore, the shielding plate 5 is set between the adjacent superposition jet nozzles along the axial direction of the outer peripheral wall of the injection rod so as to prevent the diffusion and interference of the jet flow ejected from the superposition jet nozzle.
As shown in FIG. 6, the shielding plate 5 of the fourth embodiment can be used in combination with the cylindrical shielding body 4 of the third embodiment to cope with the construction environment.

  Example 5 is for activating the crushing crushing energy generated at the difference interface of the hardener discharge amount by actively discharging excess slime by using air and adjusting the discharge amount of the hardener. An excavation / discharge blade 6 extending like an auger blade along the outer peripheral wall surface of the injection rod was set between the injection nozzles, and the slime was crushed and pumped up.

  The air-entrained jet sprayed from the superposition jet nozzle excavates and agitates the surrounding soil, and creates an excess compaction as excess slime by the amount that the amount of the spray hardener exceeds the porosity present in the surrounding soil. The discharge blade 6 is configured such that the lower end scraping portion 61 scoops out slime pushed out by overconsolidation to increase the porosity at the difference interface portion of the discharge amount of the cured material and activate the cavitation crushing energy.

  The present invention works as it is by strengthening support of the foundation foundation ground, or by injecting a ground hardening material into the target ground at a high pressure for the purpose of stabilizing the ground and stopping water, and creating a ground hardening material injection layer in the ground. It is designed to efficiently improve the soft ground that cannot be used for construction and construction, and has utility value in the civil engineering industry.

DESCRIPTION OF SYMBOLS 1 Injection rod 11 Injection rod tip bit 12 Injection rod tail end swivel 13 Injection rod rotation mechanism 14 Injection rod vertical movement mechanism 15 Injection rod operation mechanism 16 Injection rod lower injection hole 17 Ball valve of injection rod 2 Core nozzle of superposition injection nozzle DESCRIPTION OF SYMBOLS 21 Surrounding nozzle of superposition | polymerization injection nozzle 3 Hardening material flow path 31 of injection rod 4 Air supply path of injection rod 4 Cylindrical shielding body of nozzle opening 5 Diffusion shield plate 6 Excavation discharge blade 61 Lower end cutting part of excavation discharge blade A Upper polymerization injection nozzle B Lower polymerization injection nozzle C Second upper polymerization injection nozzle D Second lower polymerization injection nozzle G Target ground X Preliminary construction area Y Subsequent construction area

Claims (8)

Insert one or a plurality of pairs of injection rods into the target ground on the tip side wall of the injection rod. While jetting air from the surrounding nozzles of each polymerization injection nozzle, high pressure injection of the curing material from the core nozzle of the pair of upper polymerization injection nozzles, and simultaneously, from the core nozzle of the lower polymerization injection nozzle, the core nozzle of the upper polymerization injection nozzle The ground improvement method is characterized in that a hardened material injection layer is formed by rotating and raising the injection rod while high pressure jetting a hardened material with a discharge amount of 1 to 2 times that of the hardened material injected from The ground improvement method according to claim 1, wherein the outer periphery of the superposition jet nozzle is surrounded by a cylindrical shield to prevent diffusion and interference of the jet jetted from the superposition jet nozzle. The shield plate is set between adjacent superposition jet nozzles along the axial direction of the outer peripheral wall of the injection rod so as to prevent the diffusion and interference of the jet flow jetted from the superposition jet nozzle. 2. Ground improvement method described in 2 A drilling / exhausting blade extending in an auger wing shape along the outer peripheral wall surface of the injection rod is set between adjacent superposition jet nozzles, and slime is crushed and pumped out. Item 3 ground improvement method One or more pairs of superposition spray nozzles comprising a core nozzle and a surrounding nozzle that are turned to face each other with a step of about 2 to 8 cm on the side wall of the tip of the injection rod are set as a ground improvement device. The ground improvement device according to claim 5, wherein the outer periphery of a predetermined superposition jet nozzle is surrounded by a cylindrical shield. The ground improvement device according to claim 5 or 6, wherein a shielding plate is set between adjacent superposition jet nozzles along the axial direction of the outer peripheral wall of the injection rod. 8. The ground improvement device according to claim 5, 6 or 7, wherein an excavation / discharge blade projecting in an auger blade shape along the outer peripheral wall surface of the injection rod is set between adjacent superposition nozzles.

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