JP2017089158A - Management method of secondary slime treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To construct a cast-in-place concrete structure by placing concrete in an excavation hole filled with a stabilizer, even if the stabilizer after the completion of the secondary slime treatment is allowed to stand, slime is placed on the bottom of the hole. Provides a method of managing secondary slime treatment without depositing. SOLUTION: A secondary in a method of performing a primary slime treatment and a secondary slime treatment in a drilling hole filled with a stabilizing liquid and placing concrete in the drilling hole to construct a cast-in-place concrete structure. This is a slime treatment management method in which the measurement of the sand content of the stabilizing liquid near the bottom of the hole is repeated at regular intervals, and the sand content of the stabilizing liquid near the bottom of the hole is determined for each construction site. The step of confirming that the value is below the reference value and at least the sand content of the stabilizer near the hole mouth are measured, and the value is the same as or close to the sand content of the stabilizer near the bottom of the hole measured at the same time. The step of confirming the result is performed during the execution of the secondary slime treatment, and the secondary slime treatment is continued until the confirmation of both steps is completed. [Selection diagram] Fig. 2

Description

  The present invention relates to a management method for secondary slime treatment when primary slime treatment and secondary slime treatment are performed in an excavation hole filled with a stabilizing liquid.

  When constructing concrete structures such as cast-in-place concrete piles or continuous underground walls in the ground, a method of excavating the ground while supplying a stable liquid to form columnar or grooved drilling holes is necessary. Then, the stabilization liquid in the excavation hole is allowed to stand for a required time to precipitate sediments floating in the stabilization liquid, and a primary slime treatment is performed to remove sediments deposited on the bottom of the hole and becoming slime. In addition, before placing concrete, a secondary slime treatment is performed in which sand with a slow sedimentation rate deposited on the bottom of the hole after the primary slime treatment and formed into a slime is sucked and removed together with a stabilizing solution.

  For example, Patent Document 1 discloses a slime removing device for sucking slime deposited on the bottom of a pile hole together with a stabilizing liquid in the pile hole and discharging it outside the pile hole.

  The management method of the secondary slime treatment using such a slime removing device generally measures the sand fraction of the stable liquid near the hole bottom discharged from the slime treatment device, or the vicinity of the hole bottom. The removal of slime is continued until the sand content of the stable liquid near the bottom of the hole is equal to or lower than a predetermined control reference value by collecting the stable liquid and measuring the sand content. .

  However, since the secondary slime treatment management method does not grasp the state of the stabilizing liquid in the middle part of the pile hole or in the vicinity of the mouth part of the pile hole, it does not occur until the concrete is placed after the secondary slime process. If it takes an unexpected amount of time, the suspended sand may settle and slime may accumulate on the bottom of the hole. There is a risk of lowering.

  Under such circumstances, for example, in Patent Document 2, concrete is placed upward with an injection bag body arranged at the bottom of a pile hole, and an injection material is injected into the injection bag body after the concrete is hardened to A cast-in-place concrete pile construction method is disclosed in which preload is applied to the hole bottom ground by expanding downward from the bottom, and the hole bottom ground is pre-compressed to strengthen the pile tip.

JP 2000-120067 A Japanese Patent No. 3688546

  According to the method disclosed in Patent Document 2, due to the expansion of the infusion bag body, even if slime is present below the infusion bag body, it can be extruded and discharged, and the pile tip ground is compressed. As a result, the stress relief of the ground can be improved, so that the initial settlement of the cast-in-place concrete pile can be reduced.

  However, in the method of Patent Document 2, the work for applying the preload pressure to the pile tip ground is complicated, and the method for setting the size of the preload pressure or the length of the pressure holding time has not been established. It is not easy to confirm whether or not the slime deposited on the hole bottom has been sufficiently extruded and discharged.

  The present invention has been made in view of such a problem, and its main purpose is to provide a secondary in a method of placing a concrete in a drilling hole filled with a stabilizing liquid to construct a structure of cast-in-place concrete. It is to provide a management method for secondary slime treatment in which the slime is hardly deposited on the bottom of the hole even if the stabilizing liquid after the slime treatment is left standing.

  In order to achieve such an object, the secondary slime treatment management method of the present invention performs the primary slime treatment and the secondary slime treatment in the excavation hole filled with the stabilizing liquid, and then places concrete in the excavation hole. In the method of constructing a cast-in-place concrete structure, the secondary slime treatment management method, wherein the measurement of the sand content of the stabilizing liquid in the vicinity of the hole bottom is repeated at regular intervals, The process of confirming that the sand content of the nearby stable liquid is less than or equal to the control standard value set for each construction site, and at least measuring the sand content of the liquid near the hole and measuring at the same time A step of confirming that the sand content of the stabilizing liquid near the bottom of the hole is equal to or close to a numerical value, and the secondary slime treatment is continued until the confirmation of both steps is completed. .

  According to the management method of the secondary slime treatment of the present invention described above, it is confirmed that the sand fraction of the stabilizing liquid near the hole bottom is equal to or less than the management reference value determined for each construction site, and near the hole opening. By setting the sand fraction of the stable liquid of the same as or close to the sand percentage of the stable liquid near the bottom of the hole, the sand fraction is applied to the stable liquid in the entire borehole after the secondary slime treatment. It can be set below the control standard value determined for each site, and the sand content that is likely to sink with time can be greatly reduced. As a result, even when a great amount of time is required from the secondary slime treatment to the concrete placing operation, the slime is hardly deposited on the bottom of the excavation hole immediately before the concrete placement. Accordingly, it is possible to suppress settlement due to slime and a decrease in tip support force with respect to the structure after construction.

  In addition, the stable liquid after the completion of the secondary slime treatment is in a state where the sand content rate in the entire excavation hole is uniformly controlled, so that there is no occurrence of replacement failure when placing concrete and a high quality site It becomes possible to construct a cast concrete structure.

  The management method of the secondary slime treatment of the present invention is the method of cast-in-place concrete construction in which after the primary slime treatment and the secondary slime treatment are carried out in the excavation hole filled with the stabilizing liquid, concrete is placed in the excavation hole. A secondary slime treatment management method in a method for constructing a structure, in which the measurement of the sand content of the stable liquid near the hole bottom is repeated at regular intervals, and the sand content of the stable liquid near the hole bottom is measured. The process to confirm that the rate is below the control standard value set for each construction site, and at least the specific gravity of the stable liquid near the hole bottom and the specific gravity of the stable liquid near the hole mouth were measured and measured at the same time A step of confirming that the specific gravity of both falls within the range of the control standard value determined for each construction site, and continuing the secondary slime treatment until the confirmation of both steps is completed. And

  According to the management method of the secondary slime treatment of the present invention described above, since the specific gravity and the sand content rate are correlated, the slime deposition is performed in the same manner as the method in which the secondary slime treatment is managed only by the sand content rate. In addition to providing a restraining effect and a good replacement function with concrete, the stabilizing liquid after the completion of the secondary slime treatment is in a state where the specific gravity of the entire borehole is uniformly controlled. For each excavation hole having different ground conditions, it is possible to evaluate whether or not the stable liquid in the entire excavation hole has good properties.

  ADVANTAGE OF THE INVENTION According to this invention, the stable liquid of the whole excavation hole after the completion | finish of a secondary slime process can be made into the state by which the sand component with high possibility of settling with time progress was reduced significantly. As a result, even when a great amount of time is required from the completion of the secondary slime to the concrete placing operation, the slime is hardly deposited on the bottom of the excavation hole, and the slime can be applied to the constructed structure. It is possible to suppress the settlement due to the lowering and the decrease in the tip support force.

It is a figure which shows the excavation hole after completion | finish of a primary slime process. It is a graph which shows the state of the stable liquid in a digging hole. It is a figure which shows the excavation hole under secondary slime process implementation.

  The management method of the secondary slime treatment of the present invention is a construction method for constructing a cast-in-place concrete structure in the ground, and the primary slime treatment and the secondary slime treatment are performed in the excavation hole filled with the stabilizing liquid. It is adopted for the construction method including the process to be carried out. Therefore, it can be applied to cast-in-place pile method such as earth drill method, reverse method, all-casing method and underground continuous wall method, and the shape of the drilling hole can be either columnar or grooved, Any of underground underground walls and foundation piles may be used.

  The stabilizing liquid that fills the excavation hole may be either a bentonite stabilizing liquid or a polymer stabilizing liquid. Depending on the ground conditions and the properties of the concrete to be placed, the stability of the hole wall and the separability of the excavated soil In consideration of the substitutability of concrete and concrete, those appropriately blended may be adopted.

  In this embodiment, in order to construct a cast-in-place concrete pile by an earth drill method, a columnar excavation hole is formed in the ground, and the inside is filled with a bentonite-based stabilizing liquid as an example. Description will be given below with reference to FIG.

  As shown in FIG. 1, the excavation hole 1 was excavated by rotating a drilling bucket (not shown) while injecting a stabilizing liquid 2 suitable for the soil after the casing 3 was built on the surface layer 7 of the target ground. It has been excavated to the support layer 8. In addition, after the excavation work is finished, the soil and sand floating in the stabilizing liquid 2 is allowed to stand for a certain period of time, and the sediment is deposited on the bottom of the excavation hole 1 to form a slime. Etc. The primary slime treatment discharged to the ground is performed.

  As can be seen from the graph showing the relationship between the depth and the specific gravity in FIG. 2 (a), the stable liquid 2 in the excavation hole 1 has a fine sedimentation rate that has not settled at the end of the primary slime treatment (time point t1). The sand is floating and the specific gravity in the depth direction is high. When the stabilizing liquid 2 in the excavation hole 1 is allowed to stand for a predetermined time (time point t2), the fine sand that has floated in the stabilizing liquid 2 gradually settles, so that the specific gravity gradually decreases in the entire depth direction. It can be seen that the sedimented sand accumulates on the bottom of the hole as slime.

  For this reason, the secondary slime treatment for the excavation hole 1 starts when the sediment of the slow sedimentation speed that has floated by allowing the stabilizing liquid 2 to stand for a predetermined time after the primary slime treatment has progressed (time point t2). To do. In addition, as a selection method of the time (time t2) which starts a secondary slime process, as shown in FIG. Collect the Stabilizer 2 and measure the specific gravity at a fixed point. Then, taking into account the sedimentation speed of the sand floating in the stabilizing liquid 2, the properties of the stabilizing liquid 2, the on-site situation, etc., a specific gravity as a reference for starting the secondary slime treatment was set in advance and fixed point measurement was performed. A method of selecting the time at which the specific gravity is reduced to the reference specific gravity as the time at which the secondary slime process is started can be employed.

  In the secondary slime treatment, as shown in FIG. 3, the slime deposited on the bottom of the hole is sucked together with the stabilizing liquid 2 by the slime treatment device 4 and discharged to the ground. At this time, simultaneously with the suction of the stabilizing liquid 2 existing in the vicinity of the hole bottom, the same amount of the stabilizing liquid 2 as the stabilizing liquid 2 sucked through the stabilizing liquid supply pipe 5 is additionally supplied. The liquid level is always kept constant.

  The additionally supplied stabilizing liquid 2 is either a new liquid that has been newly produced as the stabilizing liquid 2 or a recycled liquid that has been regenerated at a stabilizing liquid plant (not shown) from the stabilizing liquid 2 containing slime discharged to the ground. It may be adopted. Further, the slime treatment device 4 sucks the slime deposited on the bottom of the excavation hole 1 together with the stabilizing liquid 2, such as a sand pump method, an air lift method, a suction pump method, etc., which are generally used for the secondary slime treatment, to the ground. Any device that can discharge can be used.

  Such a management method for secondary slime treatment is to repeatedly measure the sand content ratio that is correlated with the specific gravity of the stabilizing liquid 2 near the bottom of the hole at regular intervals. This is a method in which the secondary slime process is terminated when the value becomes equal to or less than a predetermined management reference value. The management reference value is a numerical value described as a management method for the stable liquid in a construction plan established for each construction site when a cast-in-place concrete structure is constructed. However, in the above management method, since the sand content ratio of the hole portion and the intermediate portion of the excavation hole 1 is not confirmed, the sand content ratio of the stable liquid 2 near the bottom of the hole is equal to the stable liquid 2 in the excavation hole 1. It is not possible to evaluate whether the total sand content is reflected.

  On the other hand, regarding the stabilizing liquid 2 in the excavation hole 1, the inventors have determined that the stabilizing liquid 2 in the vicinity of the hole is up to a numerical value that is the same as or close to the sand fraction of the stabilizing liquid 2 in the vicinity of the hole bottom that has been reduced to the control standard value or less. If the sand content ratio of the slag is reduced, the sand content ratio of the entire stabilizing liquid 2 in the excavation hole 1 can be reduced to the control standard value or less. It has been found that it is possible to achieve a greatly reduced state.

  Therefore, in this embodiment, not only the stabilizing liquid 2 in the vicinity of the hole bottom but also the sand content ratio in the stabilizing liquid 2 in the entire excavation hole 1 is grasped, and the relationship between the depth and the sand content ratio in FIG. As shown in the graph, the management method of the secondary slime treatment shown below is adopted so that the sand content rate is uniform in the depth direction in the stabilizing liquid 2 after the completion of the secondary slime treatment (time point t3). .

  The management method of the secondary slime treatment in the present embodiment is carried out as the management of the secondary slime treatment, repeatedly measuring the sand fraction for the stabilizing liquid 2 in the vicinity of the hole bottom at regular intervals, In the first embodiment or the second embodiment, after carrying out a process (hereinafter referred to as a conventional process) for confirming that the sand content rate is less than or equal to the management standard value determined for each construction site. The process shown is added.

<First Embodiment>
In the management method of the secondary slime treatment of the present embodiment, in addition to the conventional process for measuring the sand fraction of the stabilizing liquid 2 near the hole bottom, at least the sand fraction of the stabilizing liquid 2 near the hole mouth is measured. And performing a step of confirming that the sand fraction of the stabilizing liquid 2 near the hole mouth is a numerical value that is the same as or close to the sand percentage of the stabilizing liquid 2 near the hole bottom measured at the same time. And it is confirmed that the sand content rate of the stabilizing liquid 2 near the hole bottom is equal to or less than the control reference value determined for each construction site, and the sand content rate of the stabilizing liquid 2 near the hole mouth is the same time. The secondary slime treatment is continued until it is confirmed that the measured value is the same as or close to the sand fraction of the stabilizing liquid 2 in the vicinity of the hole bottom.

  For example, as shown in FIG. 3, the sand fraction is measured by fixed point measurement in which samplers 61 and 62 are installed in the vicinity of the hole mouth and the bottom of the hole, samples are taken at regular intervals and measured on the ground. It is good to do. The sampler 61 installed in the vicinity of the hole opening may be set to the same depth as the specific depth at which the specific gravity measurement was performed in order to select the time to start the secondary slime process described above. Moreover, the sampler 62 installed in the vicinity of the hole bottom is set to a depth determined as a management method of the stable liquid in a construction plan established for each construction site when measuring the sand content ratio in the conventional process.

  In this case, it takes a lot of work to construct the rebar cage in the excavation hole 1 and insert the tremely pipe before the concrete is placed. Even when time is required, slime is hardly deposited on the bottom of the excavation hole 1 immediately before the concrete is placed. Thereby, even when the stabilizing liquid 2 is left standing for a long time, it is a troublesome practice to place the concrete after stirring the stabilizing liquid 2 in the vicinity of the hole bottom and diffusing the slime. Without performing the work, it is possible to suppress a decrease in the tip support force due to the slime for the cast-in-place concrete pile after construction.

  In addition, since the stabilizing liquid 2 after the completion of the secondary slime treatment is in a state where the sand content ratio in the entire excavation hole is uniformly controlled, the stabilizing liquid is entrained by impairing the fluidity of the concrete being placed. Therefore, it is possible to construct a high quality on-site cast-in-place concrete pile without causing a defective replacement at the time of placing the concrete.

  Any method may be used to determine that the sand fraction of the stabilizing liquid 2 near the hole mouth is a numerical value that approximates the sand fraction of the stabilizing liquid 2 near the hole bottom measured at the same time. The allowable range is set in consideration of the composition of the stabilizing liquid 2, the properties at the time of liquid preparation, the ground conditions and the construction conditions. Even if the difference between the sand content of the stabilizing liquid 2 near the hole mouth and the sand content of the stabilizing liquid 2 near the hole bottom measured at the same time falls within the set allowable range. Good.

<Second Embodiment>
As described above, since the specific gravity and the sand content rate are in a correlation, in the second embodiment, as shown in the graph showing the relationship between the depth and the specific gravity in FIG. In the stabilizing liquid 2 after the end of the treatment (time point t3), the sand fraction and the specific gravity are used in the management method of the secondary slime treatment so that the specific gravity becomes uniform in the depth direction.

  Specifically, in addition to the conventional process of measuring the sand fraction of the stabilizing liquid 2 near the hole bottom, the specific gravity of the stabilizing liquid 2 near the hole bottom and the specific gravity of the stabilizing liquid 2 near the hole mouth are measured, A process is performed to confirm that the specific gravity of both measured at the same time falls within the range of the management standard value determined for each construction site. Then, it is confirmed that the sand fraction of the stabilizing liquid 2 near the hole bottom is less than the control reference value, and the stability liquid 2 near the hole bottom measured at the same time as the specific gravity of the stabilizing liquid 2 near the hole mouth. The secondary slime process is continued until it is confirmed that both specific gravity values are within the control standard value range.

  The specific gravity is measured at the same depth position as in the first embodiment, samplers 61 and 62 are installed near the hole mouth and near the hole bottom, samples are taken at regular intervals and measured on the ground. It is good to make measurements.

  In this way, as in the management method shown in the first embodiment, even when a great amount of time is required from the end of the secondary slime treatment to just before the concrete is placed, Slime does not almost accumulate, and there is no substitution failure when placing concrete. In addition, since the specific gravity of the entire area of the excavation hole is uniformly controlled, it is possible to stably suppress the collapse of the hole wall until just before the concrete is placed.

  Furthermore, since the secondary slime treatment management method incorporates not only the sand fraction but also the specific gravity, the stable liquid 2 in the entire excavation hole 1 is in good condition for each excavation hole 1 that has different ground conditions at the construction site. It is possible to determine whether or not Therefore, for example, if the specific gravity of the stabilizing liquid 2 in the vicinity of the hole bottom and in the vicinity of the hole does not fall within the control reference value range even after the preset time has elapsed, It can be used as an index for determining the necessity of good liquid replacement, such as replacing the entire amount of the liquid 2.

  The management method of the secondary slime process in the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the present embodiment, the sand fraction and specific gravity were measured at two points near the bottom of the hole and near the hole mouth, but in addition to these, a plurality of measurement points were set at different positions in the depth direction of the borehole 1. It may be provided.

  In addition, the sand percentage measurement method may employ either a method using an electrical resistivity sensor or a method using a sand content meter. Similarly, the specific gravity measurement method may be a method using mud balance or a float. Any method such as a method using a child type hydrometer may be adopted. Thus, if it is a method which can measure the sand fraction and specific gravity of the same time about the stabilizing liquid 2 of the several measurement point installed in the position which is different in the depth direction of the excavation hole 1, the method of measuring in the original position Alternatively, any measurement method of collecting a sample and measuring on the ground may be used.

  Furthermore, when collecting the sample, either the method of collecting using the sampler or the method of collecting the stabilizing solution 2 discharged from the slime treatment device 4 may be adopted for the stabilizing solution 2 near the hole bottom.

  Moreover, in this Embodiment, although the method of erection of a reinforcing steel basket was shown after completion | finish of a secondary slime process, after constructing a reinforcement car, it is secondary to the construction method which implements a secondary slime process. You may employ | adopt the management method of a slime process.

DESCRIPTION OF SYMBOLS 1 Drilling hole 2 Stabilizing liquid 3 Casing 4 Slime processing apparatus 5 Stabilizing liquid supply pipe 61 Sampler 62 Sampler 7 Surface layer 8 Support layer

Claims (2)

Secondary slime treatment in a method of constructing a cast-in-place concrete structure by placing concrete in the excavation hole after performing primary slime treatment and secondary slime treatment in the excavation hole filled with the stabilizing liquid Management method,
Repeat the measurement of the sand content of the stable liquid near the bottom of the hole at regular intervals to confirm that the sand content of the stable liquid near the bottom of the hole is below the control standard value set for each construction site. Process,
Measuring at least the sand content of the stabilizing liquid near the hole mouth, and confirming that the sand content of the stabilizing liquid near the hole bottom measured at the same time is the same or approximate numerical value,
The secondary slime treatment management method, characterized in that the secondary slime treatment is continued until confirmation of both steps is completed. Secondary slime treatment in a method of constructing a cast-in-place concrete structure by placing concrete in the excavation hole after performing primary slime treatment and secondary slime treatment in the excavation hole filled with the stabilizing liquid Management method,
Repeat the measurement of the sand content of the stable liquid near the bottom of the hole at regular intervals to confirm that the sand content of the stable liquid near the bottom of the hole is below the control standard value set for each construction site. Process,
At least measure the specific gravity of the stabilizer near the bottom of the hole and the specific gravity of the stabilizer near the hole, and the specific gravity of both measured at the same time should be within the range of the control standard value set for each construction site. A step of confirming,
The secondary slime treatment management method, characterized in that the secondary slime treatment is continued until confirmation of both steps is completed.

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