JP7452249B2 - Vacuum consolidation management system and quality control method for ground improvement work - Google Patents

Description

The present invention relates to a vacuum consolidation management system used in a vacuum consolidation method, and a quality control method for ground improvement work using the vacuum consolidation management system.

Vacuum consolidation methods have traditionally been used to promote consolidation settlement and increase strength of soft ground. The vacuum consolidation method is a construction method that uses vacuum pressure (negative pressure) to discharge pore water and air in soft ground, promotes subsidence of the ground in a short period of time, and increases shear strength. No. 1 discloses a method of applying negative pressure to soft ground using a drain material.

Specifically, a plurality of vertical drain materials are buried at intervals in soft ground, and the upper ends of the buried drain materials are connected to each other with a water collection pipe. A vacuum pump is connected to this water collection pipe, and by operating the vacuum pump, the pressure inside the soft ground is reduced through the water collection pipe and the vertical drain material, thereby promoting consolidation.

Japanese Patent Application Publication No. 2001-226951

When implementing the above-mentioned vacuum consolidation method, it is generally assumed that a constant vacuum pressure will be continuously applied to the entire area to be constructed, and that there will be no deformation that will affect the amount of subsidence in the area to be constructed or the surrounding ground. Predict the possibility of occurrence, etc.

In addition, if there is a possibility that the target amount of settlement may not be achieved, loading embankment construction is also used, or if there is a possibility that the surrounding ground may be affected, supplementary construction methods are implemented. However, the work of implementing such countermeasures is complicated, and the construction period tends to be long and the construction cost tends to be enormous.

In addition, after the improvement, the site will be used for various purposes, such as heavy structures such as high-rise buildings, or lightweight structures such as roads, etc., and if the construction target area covers a wide area, It is assumed that areas with different uses will coexist within the improved premises. In such cases, even if there is no uneven settlement on the site immediately after the improvement, residual settlement will occur in proportion to the weight of the structure after a structure has been constructed according to its purpose, and the structure will not be constructed in the future. It is also possible that uneven settlement may occur between the two.

However, when implementing the vacuum consolidation method, it is necessary to predict future uneven settlement that may occur due to residual settlement due to the use of the site after improvement, and to adjust the vacuum pressure to be applied to the construction target area. The method of setting and controlling the amount of subsidence has not been studied.

The present invention was made in view of the above problems, and its main purpose is to economically and efficiently increase the strength of soft ground while obtaining high-quality improved ground using the vacuum consolidation method. Another object of the present invention is to provide a vacuum consolidation management system and a quality control method for ground improvement work using the vacuum consolidation management system.

In order to achieve this object, the vacuum consolidation management system of the present invention is a vacuum consolidation management system for quality control of ground improvement work that aims to increase the strength of soft ground by vacuum consolidation method. and a vacuum consolidation control device that controls the amount of subsidence of the soft ground based on the measurement results of the measurement item, and the measurement item is at least the amount of subsidence of the soft ground. The vacuum consolidation control device includes a target curve creation section and a consolidation load adjustment section, and the target curve creation section changes the amount of settlement of the soft ground over time to reach the target final settlement amount. A target settlement curve is created as an index for achieving the target settlement curve, and the consolidation load adjustment unit calculates the amount of settlement of the soft ground after adjustment based on the target settlement curve and the measurement result of the amount of settlement. It is characterized by adjusting the consolidation load in a timely manner so that it changes over time .

In the vacuum consolidation management system of the present invention, the soft ground is divided into a plurality of divisions, and the vacuum consolidation control device further includes an inter-division adjustment section, and the inter-division adjustment section is configured to divide the soft ground into a plurality of divisions. The method is characterized in that the consolidation load for each section is adjusted in a timely manner based on the settlement curve, the measured value of the amount of settlement, and the measured value of the amount of settlement in adjacent sections.

In the vacuum consolidation management system of the present invention, the measurement items include the amount of pore water pumped in the soft ground and the vacuum pressure, and the consolidation load adjustment section adjusts the consolidation load by increasing or decreasing the amount of pumped water or the vacuum pressure. It is characterized by

In addition, the quality control method for ground improvement work of the present invention uses the vacuum consolidation management system of the present invention to control the quality of ground improvement work that aims to increase the strength of soft ground by the vacuum consolidation method. A quality control method for improvement work includes a step of creating a target settlement curve that serves as an index for changing the amount of subsidence of the soft ground over time to reach the target final settlement amount, and applying a consolidation load to the soft ground. , a step of measuring the measurement items at the management time, adjusting the consolidation load based on the measured value of the amount of settlement among the measurement items and the target settlement curve, and adjusting the amount of settlement of the soft ground after adjustment. The method is characterized by comprising a step of controlling the temperature to change over time along the target subsidence curve.

In addition, the quality control method for ground improvement work of the present invention uses the vacuum consolidation management system of the present invention to control the quality of ground improvement work that aims to increase the strength of soft ground by the vacuum consolidation method. In a quality control method for improvement work, there is a process of dividing the soft ground into sections according to the target final settlement amount, and an index for changing the settlement amount of the soft ground over time in each section to reach the target final settlement amount. A step of creating a target settlement curve, a step of applying a consolidation load to each section and measuring the measurement items at a management time, and a step of creating a target settlement curve and a measured value of the amount of settlement for each section. and a step of adjusting the consolidation load based on the measured value of the amount of settlement in the adjacent section, and controlling the amount of settlement of the soft ground after adjustment so that it changes over time along the target settlement curve. It is characterized by

According to the vacuum consolidation management system and quality control method for soil improvement work of the present invention, measurement items measured during soil improvement work can be centrally managed by the vacuum consolidation management system, and consolidation can be adjusted based on the measurement items. The amount of settlement can be controlled by applying a load to the soft ground. This makes it possible to efficiently increase the strength of soft ground and construct high-quality improved ground.

In addition, if the target final settlement amount is set based on the ground strength required for the site use after the improvement, it is possible to It becomes possible to suppress residual settlement to a minimum. In addition, since the area to be improved is not excessively promoted to consolidate, it is possible to contribute to a reduction in construction costs, such as reducing the operating costs of various equipment including vacuum pumps, water pumps, etc. In addition, it is possible to streamline ground improvement work by eliminating unnecessary earth covering work.

In addition, if the construction target area covers a wide area and areas with different uses coexist on the site after the improvement, the construction target area is divided into sections according to the future site use, and the target final settlement amount for each division is calculated after the improvement. It can be set based on the ground strength required for the site use. This makes it possible to suppress the phenomenon of uneven settlement occurring between structures in the future due to residual settlement caused by constructing structures according to the site use.

According to the present invention, since the amount of settlement is controlled by applying a consolidation load adjusted based on the measured values of measurement items used for quality control to the soft ground, the strength of the soft ground can be increased economically and efficiently. It becomes possible to obtain high quality improved ground.

1 is a diagram schematically showing a vacuum consolidation management system in an embodiment of the present invention. FIG. 2 is a diagram showing how a construction target area is divided into sections and a vacuum consolidation method is implemented in an embodiment of the present invention. It is a figure showing the flow of the quality control method of the ground improvement work by the vacuum consolidation method in an embodiment of the present invention. It is a figure showing the flow of advance preparation of the quality control method of ground improvement work by the vacuum consolidation method in an embodiment of the present invention. It is a figure showing the concept of the adjustment method of consolidation load in an embodiment of the present invention. FIG. 3 is a diagram showing how the construction target area has subsided due to the vacuum consolidation method according to the embodiment of the present invention. It is a figure which shows the flow at the time of dividing the construction target area and implementing a vacuum consolidation method in embodiment of this invention. FIG. 2 is a diagram showing how each section sinks when a construction target area is divided into sections and a vacuum consolidation method is implemented in an embodiment of the present invention. It is a figure which shows the concept of the adjustment method of the consolidation load at the time of carrying out the vacuum consolidation method by dividing the construction target area|region in embodiment of this invention. It is a figure which shows the auxiliary construction method when carrying out the vacuum consolidation construction method by dividing the construction target area in embodiment of this invention. It is a figure showing an example of a vacuum consolidation method using a vertical drain in an embodiment of the present invention. It is a figure which shows the case where the soil drainage apparatus in embodiment of this invention has several water collection layers.

The present invention is a system and method for quality control of ground improvement work using the vacuum consolidation method, in which a target final settlement amount is set in advance in order to develop a desired ground strength in a construction target area set on soft ground. , the consolidation load is controlled to satisfy this target final settlement amount.

In this embodiment, the vacuum consolidation method using a soil drainage device, which will be described later, will be taken as an example, and the details of the vacuum consolidation management system and the quality control method of ground improvement work using the vacuum consolidation method will be explained below with reference to Figures 1 to 12. I will explain while referring to it.

As shown in FIG. 1, a construction target area 10 set on soft ground G includes a soil drainage device 1 and a measuring device 200 for measuring measurement items required for quality control during construction. , are placed at appropriate positions. Further, the measuring device 200 constitutes a vacuum consolidation management system 300 together with the vacuum consolidation control device 100.

<Soil drainage device>
The soil drainage device 1 is a device that discharges pore water and air by applying a consolidation load P to the soft ground G, and includes a water collection layer 2 that collects the pore water, and a water collection layer 2 that drains the soft ground through the water collection layer 2. Negative pressure applying equipment 3 for applying negative pressure to G is provided.

Water catchment layer 2 uses sand mat, which is a highly permeable sand bed made of high-quality sand or sand containing gravel, which has high permeability and can be laid flat on the ground. Any one may be used as long as it is suitable. For example, it may be a horizontal drain material, a three-dimensional net, a gravel mat, a combination of a sand mat and a water-permeable sheet, etc.

The negative pressure equipment 3 includes a water tank 31 erected in the soft ground G, a communication section 32 provided on the side wall of the water tank 31, a pressure reducing device 33 that reduces the pressure inside the water tank 31, and a pressure reducing device 33 that reduces the pressure inside the water tank 31. A drainage device 34 is provided for discharging the interstitial water accumulated in the pores.

The water tank 31 is a cylindrical container having watertightness and airtightness, and a communication part 32 is provided on the peripheral wall near the lower end thereof. The water tank 31 may have any shape or structure as long as it is configured to be airtight. Further, the communication portion 32 is provided at a height to be buried in the water collection layer 2, and allows the inner space of the water storage tank 31 and the water collection layer 2 to communicate with each other. Note that the communication portion 32 may employ any structure, such as using a strainer, as long as it allows moisture and air to pass through but can suppress the inflow of earth and sand.

The pressure reducing device 33 includes an exhaust pipe 331 whose one end is inserted into the water storage tank 31, and a vacuum pump 332 to which the other end of the exhaust pipe 331 is connected. These operate the vacuum pump 332 to exhaust and reduce the pressure of the air primarily stored in the water tank 31 via the exhaust pipe 331. The drainage device 34 includes a water pump 341 whose one end is inserted into the water storage tank 31 and a water pump 342 which is connected to the water pump 341 within the water storage tank 31. Thereby, by operating the water pump 342, the stored water primarily stored in the water tank 31 can be pumped up.

According to the soil drainage device 1 having such a configuration, by operating the vacuum pump 332 of the pressure reducing device 33 to reduce the pressure inside the water storage tank 31, water is drained from the communication portion 32 through the water collection layer 2 facing them. Negative pressure can be applied to the soft ground G layered above it. Further, by operating the water pump 342 of the drainage device 34, it is possible to similarly apply negative pressure to the soft ground G.

In other words, the pore water in the soft ground G that is forcibly sucked and drained into the water storage tank 31 via the water collection layer 2 by the negative pressure acting on the soft ground G due to the operation of the vacuum pump 332 is transferred to the drainage device 34. The water is pumped up via the water pump 342. Then, negative pressure will act on the soft ground G layered above from the communication portion 32 via the water collection layer 2 facing these.

Therefore, in the soil drainage device 1, the negative pressure when the vacuum pump 332 of the pressure reducing device 33 is operated and the stored water level W in the water storage tank 31 are set (adjustment of the pumped water amount when the water pump 342 is operated). The consolidation load P applied to the construction target area 10 can be adjusted by both. For this reason, although not shown, the pressure reducing device 33 is equipped with a pressure gauge that is used when the vacuum pump 332 is operated. Although not shown in the drawings, the drainage device 34 is equipped with a flow meter that measures the amount of pumped pore water and a water level meter that measures the water level W in the water storage tank 31.

Note that the negative pressure when the vacuum pump 332 is operated and the stored water level W in the water storage tank 31 are measurement items related to operation management as described above, and the amount of pore water discharged is a measurement item related to subsidence management. . Therefore, the pressure gauge provided in the pressure reducing device 33 and the flow meter and water level meter provided in the drainage device 34 for measuring these are all included in the measuring device 200 described later.

≪≪Quality control method for ground improvement work≫≫
In the construction target area 10 where ground improvement work will be carried out using the soil drainage device 1 described above, the use of the site after improvement has often already been determined, and heavy structures such as skyscrapers will be constructed. The applications are various, such as the construction of lightweight structures such as roads, the construction of underground structures, or the use of sites that allow uneven settlement. Therefore, the ground strength required for the construction target area 10 after improvement also differs depending on the use of the site.

Therefore, in the quality control method for ground improvement work using the vacuum consolidation method, a target final settlement amount Sf is set for the construction target area 10 so as to develop strength commensurate with the use of the site after improvement. Then, by adjusting the consolidation load P in a timely manner so as to satisfy this target final settlement amount Sf, the amount of settlement in the construction target area 10 is controlled.

In this way, it is possible to minimize the residual settlement that occurs in the ground after the improvement due to the construction of structures etc. according to the purpose of the site after the improvement. In addition, since the construction target area 10 is not excessively promoted to consolidate, it is possible to reduce the operating costs of the pressure reducing device 33 and the drainage device 34 including the vacuum pump 332, the water pump 342, etc., thereby contributing to a reduction in construction costs. In addition, it is possible to streamline the entire ground improvement work by eliminating unnecessary earth covering work.

In addition, if the construction target area 10 covers a wide area and areas with different uses coexist on the site after improvement, the construction target area 10 can be divided into multiple sections as shown in FIGS. 2(a) and 2(b). (section 10A to section 10D). After that, it was decided that the target final settlement amount Sf would be set for each section based on the ground strength required for the use of the improved site, and ground improvement work would be carried out.

In this way, it is possible to suppress the phenomenon in which uneven settlement occurs between structures in the future due to residual settlement caused by constructing structures according to the purpose of the site. In addition, when implementing ground improvement work by setting a different target final settlement amount Sf for each section, each section is affected by the construction situation in the adjacent section. Therefore, when adjusting the consolidation load P, in addition to the target final settlement amount Sf set for each section, the adjustment is made in a timely manner while monitoring the measured value of the settlement amount of the adjacent section.

≪Vacuum consolidation management system≫
In carrying out the quality control method as described above, a vacuum consolidation control system 300, which will be described below, is used. The vacuum consolidation management system 300 includes a measuring device 200 and a vacuum consolidation control device 100, as shown in FIG.

<Measuring device>
The measuring device 200 includes a pressure gauge provided in the pressure reducing device 33 and a pressure gauge provided in the drainage device 34 to measure the negative pressure caused by the vacuum pump 332 and the water level W stored in the water storage tank 31, which are measurement items related to operation management as described above. In addition to a water level meter and a flow meter installed in the drainage device 34 for measuring the discharge amount of pore water, which is a measurement item related to subsidence management, a subsidence amount measuring section 201 and a water pressure measuring section 202 as shown in FIG. It is equipped with

The subsidence measurement unit 201 measures the subsidence amount of the ground surface in the construction target area 10, and can employ a subsidence plate (which can be a target of a total station), a water embankment type subsidence meter, or the like. Further, the water pressure measurement unit 202 measures pore water pressure in order to check the consolidation load P in the soft ground G, and employs a pore water pressure gauge. Note that, as the settling plate and the pore water pressure gauge, measuring instruments generally employed in the vacuum consolidation method can be used. In addition, both the amount of subsidence and pore water pressure are included in the measurement items related to subsidence management.

<Vacuum consolidation control device>
As shown in FIG. 1(b), the vacuum consolidation control device 100 includes an input section 110, an output section 120, a storage section 130, and an arithmetic processing section 140 such as a CPU, GPU, ROM, RAM, and a hardware interface. It is composed of a computer system.

The input unit 110 supplies the vacuum consolidation control device 100 with information input from input devices such as a keyboard and a mouse, as well as the measurement device 200 described above. The output unit 120 also outputs information supplied from the input unit 110 and information stored in the storage unit 130 to an output device such as a display or a printer, or to the decompression device 33 and drainage device 34 that constitute the soil drainage device 1. Output to. The functions of the target curve creation section 141, the consolidation load adjustment section 142, and the inter-compartment adjustment section 143 are realized by the CPU of the arithmetic processing section 140 executing a predetermined program.

≪Quality control method for ground improvement work using vacuum consolidation method≫
A quality control method for ground improvement work using the vacuum consolidation management system 300 described above will be described below along with details of the vacuum consolidation control device 100 along the steps shown in the flows of FIGS. 3 and 4.

≪≪Quality control method for ground improvement work when the construction target area is not divided into sections≫≫
<Advance preparation>
When implementing the vacuum consolidation method on the construction target area 10 that is not divided into sections as shown in Figure 1, as a preliminary preparation, the target final settlement amount Sf of the construction target area 10 is set and the target final settlement amount Sf is achieved. A target settlement curve TC is created for this purpose, and a consolidation load P to be applied to the construction target area 10 is set.

Specifically, the arithmetic processing unit 140 of the vacuum consolidation control device 100 receives a command from the target curve creation unit 141, and sets the target final settlement amount Sf and sets the target settlement curve TC in accordance with the procedure shown in the flowchart of FIG. Creation and setting of the consolidation load P are performed and stored in the storage unit 130 of the vacuum consolidation control device 100.

The procedure is to first determine the target final settlement amount Sf of the construction target area 10 by appropriately reflecting the ground strength and ground conditions required for the site use after improvement, as well as other matters that are generally considered when implementing the vacuum consolidation method. setting. Next, the consolidation load P to be applied to the construction target ground is set based on the target final settlement amount Sf, the scheduled operation period of the soil drainage device 1, and the like. Furthermore, a subsidence curve (a curve showing changes in the subsidence amount over time) for subsidence to the target final subsidence amount Sf at the end of the scheduled operation period of the soil drainage device 1 is estimated.

The validity of the estimated subsidence curve is verified and the optimal one is determined as the target subsidence curve TC for the construction target area 10, as shown in FIG. Furthermore, in order to apply the consolidation load P to the construction target area 10, the negative pressure to be set in the vacuum pump 332 of the pressure reducing device 33 and the stored water level W in the water storage tank 31 are calculated.

In parallel with or before or after the above-mentioned work, as shown in FIG. 1, a measuring device 200 is installed at a predetermined position in the construction target area 10, centering on the soil drainage device 1.

In the vacuum consolidation method using the soil drainage device 1, as described above, the consolidation load P is applied to the soft ground G via the communication portion 32 of the water storage tank 31 and the water collection layer 2 facing thereto. Therefore, as shown in FIG. 6(b), when the consolidation load P formed around the water tank 31 is applied, the amount of settlement is large in the vicinity of the water tank 31, and The amount of subsidence tends to decrease as the distance from 31 increases.

Therefore, when installing the measuring device 200, the settlement amount measuring section 201 and the water pressure measuring section 202 are preferably arranged so as to cover the entire plane of the construction target area 10, as shown in FIG. 6(b).

<Loading consolidation load>
When these preliminary preparations are completed, the application of the consolidation load P to the construction target area 10 is started.

The stored water level W calculated in advance in the water storage tank 31 in the soil drainage device 1 is set, and the negative pressure calculated in advance is set in the vacuum pump 332 of the pressure reducing device 33. These setting operations may be performed by a field worker by directly operating the pressure reducing device 33 and the drainage device 34, or by operating the vacuum consolidation control device 100 connected to the soil drainage device 1 wirelessly or by wire. good.

When setting by the vacuum consolidation control device 100, the arithmetic processing unit 140 of the vacuum consolidation control device 100 receives a command from the target curve creation unit 141, and sets the vacuum pressure to be set in the vacuum pump 332 of the pressure reducing device 33 and the water storage tank 31. After calculating the storage water level W within the storage area, these calculation results are stored in the storage unit 130. Further, the output may be outputted to the pressure reducing device 33 and the drainage device 34 in the soil drainage device 1 via the output unit 120.

Once the consolidation load P acting on the construction target area 10 is set, the operation of the soil drainage device 1 is started and the consolidation load P is applied. Then, due to the consolidation load P acting on the construction target area 10, pore water and air in the soft ground G are discharged to the outside via the water collection layer 2 and water storage tank 31 of the soil drainage device 1, and accordingly, the construction work is completed. The ground surface of the target area 10 gradually sinks as shown in FIG. 6(a).

The ground surface of the construction target area 10, which subsides over time in this manner, is measured by each of the plurality of subsidence measurement units 201 at every preset management time (for example, every week). The amount of settlement Si (i = individual number assigned to each of the amount of settlement measurement portions 201) measured by each of these plurality of amount of settlement measurement units 201 is correlated with time information, and then It is stored in the storage unit 130 via the input unit 110 of the control device 100.

When the settlement amount Si of the construction target area 10 at the management time is input to the vacuum consolidation control device 100, the arithmetic processing unit 140 of the vacuum consolidation control device 100 receives a command from the consolidation load adjustment unit 142, and calculates the settlement amount Si and the construction amount. The target settlement curve TC of the target area 10 is compared to verify the necessity of adjusting the consolidation load P. As a result of the verification, if it is determined that adjustment is necessary, the adjustment amount is calculated, and if it is determined that adjustment is not necessary, the adjustment amount is set to 0 and stored in the storage unit 130 together with time information. Further, it is output to the pressure reducing device 33 and the drainage device 34 of the soil drainage device 1 via the output unit 120.

Here, since the amount of settlement Si is a measurement value corresponding to the quantity i of the amount of settlement measuring unit 201 installed in the construction target area 10 is output, in the verification, the amount of settlement Si is a representative value representing the overall settlement tendency of the construction target area 10. It is preferable to calculate the value St. Note that the representative value St may be an average value, a median value, a mode value, or the like of the settlement amounts Si, which are the measured values of each of the plurality of settlement amount measurement units 201. Alternatively, instead of the representative value St, a statistical value calculated by other statistical processing may be used.

Verification to confirm the necessity of adjusting the consolidation load P is performed based on the target settlement curve TC. Any method may be used, but for example, the representative value St of the amount of settlement at the management time is added to a graph showing the relationship between the amount of settlement and time representing the target settlement curve TC of the construction target area 10, as shown in FIG. Plot.

For example, in FIG. 5, the representative value St of the amount of subsidence measured at management time t1 is plotted on the graph. Then, the settlement curve when the consolidation load P is not adjusted is predicted, and if the deviation between the predicted settlement curve and the target settlement curve TC is large, it is determined that the consolidation load P needs to be adjusted. Note that the deviation between the predicted settlement curve and the target settlement curve TC can be determined by setting a tolerance value in advance and storing it in the storage unit 130, and determining whether or not the predicted settlement curve falls within this tolerance value. It is advisable to determine whether or not adjustment of the load P is necessary.

If it is determined that adjustment is necessary, the steps are taken so that the representative value St of the amount of subsidence in the construction target area 10 changes over time along the target subsidence curve TC during the remaining period of the scheduled operation period of the soil drainage device 1. Adjust the consolidation load P. The consolidation load P is adjusted by adjusting either or both of the vacuum pressure set in the vacuum pump 332 of the pressure reducing device 33 and the water level W stored in the water storage tank 31. In addition, when the representative value St of the amount of settlement exceeds the target final amount of settlement Sf, the consolidation load P is adjusted to be zero.

The above operations are repeated every time the management time arrives until the end date of the scheduled operation period in the soil drainage device 1 arrives. As a result, after the operation of the soil drainage device 1 is completed, as shown in FIG. 5, the settlement curve (after adjustment) plotting the representative value St of the settlement amount will be in a state almost along the target settlement curve TC, and the construction target area In step 10, a high quality improved ground having the ground strength required for the site use is constructed.

Note that in this embodiment. Although the management time is set to be weekly, it may be set at appropriate intervals, and does not necessarily have to be set at regular intervals. Furthermore, at the management time, measurements are also performed using other measuring devices included in the measuring device 200, and the acquired measured values are stored in the storage unit 130. In this way, the measurement items measured during soil improvement work can be centrally managed by the vacuum consolidation control device 100, which not only makes it possible to perform construction management rationally, but also allows the measurement values accumulated through these central management to be From this, it is also possible to predict future uneven settlement that will occur in the improved ground.

≪≪Quality control method for ground improvement work when the construction target area is divided into sections≫≫
Next, as shown in FIGS. 2(a) and 2(b), the case where the construction target area 10 is divided into a plurality of sections and managed for each section (sections 10A to 10D) will be explained according to the flowchart of FIG. I will explain.

<Advance preparation>
Divide the construction target area 10 into a plurality of sections, and create a target final settlement amount Sf of the construction target area 10, a target subsidence curve TC for achieving the target final settlement amount Sf, Then, the consolidation load P to be applied to the construction target area 10 is set, and preparations are made in advance.

At this time, for example, if the site use after improvement is the same, but the construction target area 10 is a wide area and the construction target area 10 is divided into sections, the target final settlement amount Sf and the target final settlement amount Sf are achieved. The target settlement curve TC and consolidation load P for each section (section 10A to section 10D) are the same for each section (section 10A to section 10D).

On the other hand, within the construction target area 10, there are areas with different site uses after improvement, so if the site is divided into multiple sections according to the site use, each section (sections 10A to 10D) will have different goals. The final settlement amount Sf, the target settlement curve TC for achieving the target final settlement amount Sf, and the consolidation load P are set.

<Loading consolidation load>
When these preliminary preparations are completed, loading of the set consolidation load P is started on each of the sections (sections 10A to 10D) in the construction target area 10. Note that the loading procedure performed in each compartment is the same as in the case where no division is performed as described above, whether the set consolidation load P is the same or different for each compartment.

That is, after starting the operation of the soil drainage device 1, the ground surface of the sections 10A and 10B gradually sinks, as shown in FIG. 8, for example. Therefore, each of the plurality of subsidence measurement units 201 measures the subsidence amount Si (i = individual number assigned to each subsidence measurement unit 201) at each preset management time, and correlates it with time information. Then, it is stored in the storage unit 130 via the input unit 110 of the vacuum consolidation control device 100.

<Adjustment between compartments considering the influence of negative pressure in adjacent compartments>
As shown in FIGS. 2(a) and 2(b), the soil drainage devices 1 installed in each section (sections 10A to 10D) are arranged so that the influence ranges R when the consolidation load P is applied overlap. has been done. Therefore, each section is susceptible to the consolidation load P acting on adjacent sections.

Therefore, taking the section 10A as an example, the amount of settlement Si of the section 10A is stored in the storage unit 130. Then, the arithmetic processing unit 140 of the vacuum consolidation control device 100 receives a command from the inter-compartment adjustment unit 143, and in addition to the settlement amount Si, which is the measured value of the section 10A, and the target settlement curve TC, the calculation processing section 140 of the vacuum consolidation control device 100 calculates the settlement amount Si of the sections 10B to 10D. Based on this, it is verified whether the section 10A is influenced by the adjacent sections 10B to 10D.

In addition, as mentioned above, during the verification, the amount of settlement Si measured by each of the plurality of settlement amount measurement units 201 (i = individual number assigned to each of the amount of settlement measurement units 201) may be used as is. , it is preferable to calculate the representative value St of the amount of subsidence from these, and employ this representative value St of the amount of subsidence.

If it is determined that the section 10A is influenced by the sections 10B to 10D, the consolidation load P is adjusted taking these influences into consideration, and is stored in the storage unit 130 together with time information. Further, it is output to the pressure reducing device 33 and the drainage device 34 of the soil drainage device 1 via the output unit 120. Then, the operation of the soil drainage device 1 is continued.

Whether or not the area is influenced by adjacent sections can be determined, for example, by the following procedure. Taking the section 10A as an example, the graph in FIG. 9 shows the target subsidence curve TC _A of the section 10A, and also plots the representative value S _A t of the amount of subsidence measured at the management time t1. Further, the target subsidence curves TC _BCD of the adjacent sections 10B to 10D are shown, and representative values of the subsidence amounts S _B t to S _D t measured at the management time t1 are plotted. Here, it is assumed that the target subsidence curves TC _BCD are the same for the sections 10B to 10D, and the representative values S _B t to S _D t of the subsidence amounts are also the same.

In such a case, it can be seen that the division 10A has a large deviation between the subsidence curve predicted from the representative value S _A t of the subsidence amount and the target subsidence curve _TCA , and has subsided excessively compared to the design. On the other hand, for the plots 10B to 10D adjacent to the plot 10A, the settlement curve predicted from the representative values S _B t to S _D t of the settlement amount is located above the target settlement curve TC _BCD , and the amount of settlement appears to be smaller than the design. I understand.

The subsidence curve predicted from the representative value S _A t of the amount of subsidence of the section 10A is compared with the subsidence curve predicted from the representative values S _B t to S _D t of the amount of subsidence of the sections 10B to 10D. is large. As a result, there is a possibility that the pore water and air in the compartment 10A are not only discharged from the soil drainage device 1 installed in the compartment 10A, but also flow into the compartments 10B to 10D. Therefore, it can be determined that the sections (sections 10A to 10D) are influenced by each other.

For example, in the section 10A, there is a large discrepancy between the subsidence curve predicted from the representative value S _A t of the amount of subsidence and the target subsidence curve TC _A , but in the sections 10B to 10D, the representative values S _B t to S of the amount of subsidence are The subsidence curve predicted from _Dt is moving almost along the target subsidence curve TC _BCD . In such a case, it can be determined that the sections (sections 10A to 10D) are not influenced by each other. Therefore, in the compartment 10A, the consolidation load P does not need to be adjusted between compartments, and may be adjusted within the compartment 10A.

When adjusting the consolidation load P of the section 10A, first, during the remaining period of the scheduled operation period of the soil drainage system 1, the representative value S _A t of the amount of settlement in the construction target area 10 is adjusted along the target settlement curve TC _A. The consolidation load P is reduced so that it changes over time. Furthermore, taking into consideration that pore water and air flow into the sections 10B to 10D, the consolidation load P adjusted to be reduced is further reduced.

On the other hand, considering that the consolidation load P of the division 10A has been reduced compared to before the management time t1, the amount of settlement in divisions 10B to 10D will decrease if the consolidation load is not adjusted, and the soil drainage will be reduced. During the remaining period of the scheduled operation period of the device 1, there is a possibility that a large deviation from the target subsidence curve TC _BCD will occur. Therefore, in the sections 10B to 10D, adjustments are made to increase the consolidation load P in accordance with the adjustment of the section 10A.

In this way, after the scheduled operation period of the soil drainage system 1 ends, as shown in FIG. 9, the adjusted subsidence curves of each section (sections 10A to 10D) will be the target subsidence curve TC _A or the target subsidence curve. The condition is almost in line with the TC _BCD , and in the construction target area 10, high quality improved ground having the ground strength required for the site use is constructed for each section.

On the other hand, if it is determined that the section 10A is not affected by the sections 10B and 10C, the representative value S _A t of the amount of settlement is supplied to the consolidation load adjustment section 142. Then, in the same procedure as when the construction target area 10 is not divided into sections, the amount of settlement S _A t is compared with the target settlement curve TC _A of section A, and the necessity of adjusting the consolidation load P is verified.

As a result of the verification, if it is determined that adjustment is necessary, the adjustment amount is calculated, and if it is determined that adjustment is not necessary, the adjustment amount is set to 0 and stored in the storage unit 130 together with time information. Further, it is output to the pressure reducing device 33 and the drainage device 34 of the soil drainage device 1 via the output unit 120. Then, the operation of the soil drainage device 1 may be continued.

According to the vacuum consolidation management system and quality control method for ground improvement work described above, it is possible to efficiently increase the strength of soft ground and construct high-quality improved ground.

If the construction target area 10 is divided into sections and it is difficult to adjust the sections as described above, countermeasures such as installing water-blocking walls 4 at the boundaries of each section as shown in FIG. 10 may be taken. May be implemented. In this way, the sections (sections 10A to 10D) can be separated by the water-shielding wall 4, so that the effects of the consolidation load P acting on each other can be suppressed.

The vacuum consolidation management system 300 and the quality control method for ground improvement work of the present invention are not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention.

For example, in this embodiment, the soil drainage device 1 is used in the vacuum consolidation method, but the invention is not limited to this, and for example, a vertical drain 12 as shown in FIGS. 11(a) and 11(b) is used. A drainage device 11 may be adopted.

In this case, a plurality of vertical drains 12 each having a closing cap at the lower end are buried in the soft ground G at intervals. Further, the upper ends of the buried vertical drains 12 are connected to each other by a drain pipe 13. Then, a vacuum pump 14 is connected to the drainage pipe 13, and by operating the vacuum pump 14, a consolidation load P is applied to the soft ground G through the drainage pipe 13, and pore water and air are discharged. The consolidation load P can be adjusted by the negative pressure measured by a pressure gauge provided in the vacuum pump 14.

Furthermore, in this embodiment, the soil drainage device 1 is provided with one layer of water collection layer 2, and the soft ground G is deposited on the upper surface of the soil drainage device 1. However, the present invention is not necessarily limited to this. . For example, as shown in FIG. 12, a structure may be adopted in which the water catchment layer 2 and the soft ground G are alternately stacked in the depth direction.

The soil drainage device 1 of FIG. 12 is provided with communication portions 32 at positions that are in contact with the water collection layers 2 on the side surfaces of the water storage tank 31, so that the inner space of the water storage tank 31 and each of the plurality of water collection layers 2 are connected to each other. are in communication. Then, by utilizing all of the plurality of water collection layers 2, the consolidation load of the soft ground G is applied to discharge pore water and air. Then, the consolidation load P is applied uniformly in the height direction to the accumulated soft ground G, and it becomes possible to efficiently increase the strength of the soft ground.

Alternatively, the communication portions 32 may be configured to be openable and closable, and one or more of the plurality of water collection layers 2 may be selectively used to discharge pore water and air from the soft ground G. good. In this way, the consolidation load can be applied to a desired depth position of the construction target area 10. Further, when the construction target area 10 is divided into sections, the consolidation load P can be applied to different depth positions for each section. This makes it possible to apply the consolidation load in an optimal manner for each section depending on the properties of the soft ground G and the required ground strength, etc., which not only greatly improves workability but also improves the quality of the improved ground. can be constructed.

Regarding the soil drainage device 1, the configuration that allows selective use of a plurality of water collection layers 2 when discharging pore water and air from the soft ground G is not necessarily limited to the openable/closeable communication section 32. isn't it. The details are given in Japanese Patent Application No. 2020-047319.

Further, as shown in FIG. 12, when dividing the soft ground G into multiple layers, it is preferable to provide the subsidence measuring section 201 and the water pressure measuring section 202 of the measuring device 200 for each divided layer. In this way, the amount of upper surface settlement and consolidation load P for each layer in the soft ground G can be confirmed. These can also be stored in the storage unit 130 of the vacuum consolidation control device 100 as measurement items related to subsidence management each time a measurement value is acquired, and can be centrally managed.

Furthermore, when the construction target area 10 is divided into sections, the consolidation load P is applied to each soil drainage device 1 installed in each section (section 10A to section 10D), as shown in FIGS. 2(a) and 2(b). let For this reason, there is a possibility that the influence ranges R will be concentrated in overlapping areas, causing uneven settlement. Therefore, when adjusting the consolidation load P between adjacent sections, it is good to consider the magnitude of uneven settlement that occurs near these overlapping areas.

1 Soil drainage device 2 Water collection layer 3 Negative pressure equipment 31 Water storage tank 32 Communication section 33 Pressure reducing device 331 Exhaust pipe 332 Vacuum pump 34 Drainage device 341 Lifting pipe 342 Lifting pump 4 Impermeable wall 10 Construction target area 11 Drainage device 12 Vertical Drain 13 Drain pipe 14 Vacuum pump 100 Vacuum consolidation control device 110 Input section 120 Output section 130 Storage section 140 Arithmetic processing section 141 Target curve creation section 142 Consolidation load adjustment section 143 Inter-compartment adjustment section 200 Measuring device 201 Settlement measurement section 202 Water pressure Measurement section 300 Vacuum consolidation management system

G Soft ground R Influence range W Reservoir water level TC Target settlement curve Sf Target final settlement amount Si Settlement amount St Representative value of settlement amount P Consolidation load

Claims (5)

In a vacuum consolidation management system for quality control of ground improvement work that aims to increase the strength of soft ground using the vacuum consolidation method,
a measuring device that measures measurement items used for quality control of the ground improvement work;
a vacuum consolidation control device that controls the amount of subsidence of the soft ground based on the measurement results of the measurement items,
The measurement item includes at least the amount of subsidence of the soft ground,
The vacuum consolidation control device includes a target curve creation section and a consolidation load adjustment section,
The target curve creation unit creates a target subsidence curve that serves as an index for changing the subsidence amount of the soft ground over time to reach a target final subsidence amount,
The consolidation load adjustment section adjusts the consolidation load in a timely manner based on the target settlement curve and the measurement result of the amount of settlement so that the amount of settlement of the soft ground after adjustment changes over time along the target settlement curve. A vacuum consolidation management system featuring: The vacuum consolidation management system according to claim 1,
The soft ground is divided into a plurality of sections, and the vacuum consolidation control device further includes an inter-section adjustment section,
The inter-compartment adjustment unit may adjust the consolidation load for each compartment in a timely manner based on the target settlement curve and the measured value of the amount of subsidence, and the measured value of the amount of subsidence in the adjacent compartment. A vacuum consolidation management system featuring: The vacuum consolidation management system according to claim 1 or 2,
The measurement items include the amount of pore water pumped in the soft ground and the vacuum pressure,
The vacuum consolidation management system is characterized in that the consolidation load adjustment section adjusts the consolidation load by increasing or decreasing the amount of water pumped or the vacuum pressure. A quality control method for ground improvement work that uses the vacuum consolidation management system according to claim 1 or 3 to control the quality of ground improvement work that aims to increase the strength of soft ground by a vacuum consolidation method,
creating a target subsidence curve that serves as an index for changing the subsidence amount of the soft ground over time to reach the target final subsidence amount;
A step of applying a consolidation load to the soft ground and measuring the measurement items at a control time;
A step of adjusting the consolidation load based on the measured value of the amount of subsidence among the measurement items and the target subsidence curve, and controlling the adjusted amount of subsidence of the soft ground to change over time along the target subsidence curve. A quality control method for ground improvement work, comprising: A quality control method for ground improvement work, which uses the vacuum consolidation management system according to claim 2 or 3 to control the quality of ground improvement work that aims to increase the strength of soft ground by a vacuum consolidation method,
A process of dividing the soft ground into sections according to the target final settlement amount,
creating a target subsidence curve for each section, which is an index for changing the subsidence amount of the soft ground over time to reach a target final subsidence amount;
a step of applying a consolidation load to each section and measuring the measurement items at a control time;
For each section, the consolidation load is adjusted based on the target subsidence curve and the measured value of the subsidence amount, and the measured value of the subsidence amount in the adjacent section, and the adjusted subsidence amount of the soft ground corresponds to the target subsidence curve. a step of controlling the change over time along the
A quality control method for ground improvement work, characterized by comprising:

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