JP4964525B2 - Caisson settlement method and caisson settlement management system - Google Patents

Description

  The present invention relates to a caisson settlement method and a caisson settlement management system.

  Conventionally, there is an automated open caisson method as a technique for laying caisson with high accuracy. In this construction method system, a caisson is formed by sequentially forming an excavation / landing system for excavating the caisson housing, a caisson settlement management system for sinking the caisson housing with a predetermined vertical accuracy, and an annular concrete structure (lot). It consists of a chassis construction system that constructs a chassis. According to this automated open caisson method, after the inside of the cylindrical caisson housing is excavated by the excavation and excavation system, a downward introduction load is applied to the caisson housing by the press-fitting device provided in the caisson settlement management system. The caisson body is submerged in the ground by its own weight and the load applied. At this time, the position of the caisson housing is managed by the caisson settlement management system. When the caisson housing sinks to a predetermined depth, a new lot is formed at the upper end of the caisson housing to construct a caisson.

In general, the caisson settlement management system described above includes an inclinometer that measures the amount of inclination of the caisson housing, a settlement meter that measures the amount of settlement of the caisson housing, and a load meter that measures the pressure (such as jack pressure) by the press-fitting device. Often configured. The caisson housing settlement management can be performed with these instruments, and the caisson housing settlement accuracy can be ensured (see, for example, Patent Documents 1 and 2).
Japanese Patent Publication No. 2-22171 JP-A-9-59994

  However, in the above-described automated open caisson method, when a steel caisson housing is used, the resistance (peripheral frictional force, ground reaction force, buoyancy) is always greater than the caisson's own weight. However, if concrete members are used as the caisson housing, the caisson body weight may be greater than the resistance force, and the caisson housing will self-sink and become uncontrollable. There is a possibility that the caisson housing will be oversunk. And in the above-mentioned conventional technology, although it is possible to grasp the inclination amount and the sinking amount of the caisson housing, it is impossible to grasp the ground reaction force acting on the blade edge of the caisson housing. A sudden oversinking of a caisson enclosure cannot be prevented. If the caisson housing is oversunk, not only will the vertical accuracy of the caisson housing deteriorate, but for example, when using an excavator with an expandable / retractable excavator as an excavation / landing system, Since the excavating blade is expanded to the position directly below, the excavating blade may be sandwiched between the blades of the caisson housing and may not be excavated.

  The present invention has been made in consideration of the above-described conventional problems, and an object of the present invention is to provide a caisson settlement method and a caisson settlement management system capable of preventing the caisson body from self-sinking and preventing the caisson body from being oversunk. It is said.

The invention according to claim 1 is an excavation step of excavating the ground from the inside of the caisson housing, and a downward introduction load is applied to the caisson housing, so that the caisson housing is brought into the ground by its own weight and the introduction load. A caisson settlement method comprising a press-fitting step of subsidence, wherein in the excavation step, excavation is performed at an excavation depth and an excavation diameter set based on a set value of a tip ground resistance force acting on a cutting edge of the caisson housing, In the press-fitting step, one or both of a settlement meter for measuring the amount of settlement of the caisson housing and a load meter for measuring the magnitude of the introduced load is used to detect when the caisson housing starts to sink and to detect has been detected a skeleton body stress of the caisson skeleton at subsidence started, the caisson skeleton of the該躯body stress as tip ground resistance was detected The compensation value is obtained of the set value from the difference between the set value at the time of the value and the excavation process of skeleton body stress at subsidence start, after said stuffing step, the tip soil resistance force detected precursor the set value of The set value is corrected with the correction value so as to be changed to a value corresponding to the value of internal stress, and one of the excavation depth and the excavation diameter in the next excavation process based on the new set value after correction Or the adjustment process which adjusts both is performed.

  With such a feature, the set value of the tip ground resistance force for setting the next excavation depth and excavation diameter is corrected based on the detected body stress. This is because at the moment when the caisson sinks, the stress in the caisson enclosure and the tip ground resistance (blade reaction force) are almost equal to each other. This is because it can be seen as resistance. That is, since the set value in the next excavation is corrected based on the current tip ground resistance, the next excavation depth and the excavation diameter are changed in accordance with the actual field situation. Also, the moment when the caisson housing starts to sink, the settlement meter starts to move, and the load meter value decreases momentarily, so it is possible to detect when the caisson housing starts to sink from the settlement meter or load meter. is there.

  The invention according to claim 2 is the caisson settlement method according to claim 1, wherein the stress in the enclosure is measured by measuring a vertical stress generated in the caisson enclosure with a strain gauge installed in the caisson enclosure. The vertical stress is calculated by multiplying the horizontal sectional area of the caisson housing.

  With this feature, the ground reaction force received by the entire blade edge is calculated, not the biased ground reaction force as measured by a blade edge reaction force meter, etc., and the accurate tip ground resistance force can be grasped. .

  According to a third aspect of the present invention, in the caisson settlement method according to the first or second aspect, the introduction load is applied to the caisson housing by applying a downward pressing force to the caisson housing with a jack that expands and contracts in the vertical direction. The correction value is updated by detecting the stress in the casing of the caisson casing at the start of subsidence for each stroke of the jack.

  Because of this feature, the stress in the housing is detected for each jack stroke, so the stress in the housing (ground reaction force) closer to the tip ground resistance force at the start of the next press-fitting process is detected and more accurate. A correct correction value is obtained.

According to a fourth aspect of the present invention, there is provided an excavation step of excavating the ground from the inside of the caisson frame, and a downward introduction load is applied to the caisson frame so that the caisson frame is brought into the ground by the own weight of the caisson frame and the introduction load. In the caisson settlement management system in the caisson settlement method, the caisson having one or both of a settlement meter for measuring the amount of settlement of the caisson housing and a load meter for measuring the magnitude of the introduced load is provided. One of the monitoring system, the excavator performing the excavation process, and the excavation depth and the excavation diameter by the excavator based on a set value of the tip ground resistance force acting on the blade edge of the caisson housing or the excavator management system to change both, us when the value in the previous excavation process of skeleton body stress in subsidence beginning of the caisson skeleton Wherein in order to determine a correction value for correcting the setting value from the difference between the set value at the next excavation process, the caisson skeleton skeleton body stress immediately above the cutting edge of the arranged has been the caisson skeleton directly above the cutting edge of that And a stress observation system for observing.

  With such a feature, the movement and introduction load of the caisson housing are grasped by the caisson monitoring system, and the start time of the caisson housing subsidence is detected by the settlement meter and the load meter provided in the caisson monitoring system. Moreover, the stress in the housing is observed by the stress observation system, and the stress in the housing at the start of settlement is detected. In addition, the excavator management system grasps the state and movement of the excavator during the excavation process and the press-fitting process, and adjusts the excavation depth and excavation diameter based on the new set values corrected with the correction values. The

  According to the caisson settlement management system according to the present invention, since the set value of the tip ground resistance force is corrected based on the measured stress in the housing, the depth of drilling and the diameter of the drilling are adjusted so that the caisson housing does not self-sink. The caisson housing can be prevented from being oversunk.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a caisson settlement method and a caisson settlement management system according to the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view showing a construction system for the caisson settlement method according to the present embodiment.
As shown in FIG. 1, the caisson settlement method according to the present invention includes an excavation process for excavating the ground G from the inside of the caisson housing 1, a downward introduction load applied to the caisson housing 1, and the caisson housing's own weight and introduction load. Is a method of repeatedly performing the press-fitting step of sinking the caisson housing 1 into the ground G.

FIG. 2 is a cross-sectional view showing a completed form of the caisson housing 1.
As shown in FIGS. 1 and 2, the caisson housing 1 is a structure constituting a caisson foundation formed in the ground G. For example, a plurality of annular lots 50 made of reinforced concrete are stacked on the same axis. It consists of a cylindrical structure. These lots 50 may be made of precast concrete, or may be made of on-site concrete. Moreover, it is preferable that the lower end (blade 1a) of the caisson housing 1 has a pointed shape so as to cut the ground G when the caisson housing 1 is press-fitted. For example, the lowermost lot (first lot 50a) The inner peripheral surface is formed in a taper shape.

  The first lot 50a is first press-fitted into the ground G to a predetermined depth by the press-fitting device 2 described below. Thereafter, the second lot 50b is installed at the upper end of the first lot 50a, and the first lot 50a and the second lot 50b are integrated. The integrated lots 50a and 50b (caisson housing 1) are submerged to a predetermined depth by the caisson subsidence method according to the present invention, and then the third lot 50c is installed at the upper end thereof and integrated. The caisson housing 1 is extended into the ground G by repeatedly performing the sinking operation of the caisson housing 1 and the adding operation of the lot 50.

  As shown in FIG. 1, a known system can be adopted as a construction system for performing the caisson method according to the present invention, for example, for applying a downward introduction load to the vertically arranged caisson housing 1. Construction comprising a press-fitting device 2, an excavator 3 for performing the excavation process, and an excavation facility 4 for carrying excavated earth and sand generated by excavation by the excavator 3 out of the caisson housing 1 The system can be adopted.

  As the above-described press-fitting device 2, for example, a plurality of earth anchors 5 fixed in the ground G and projecting at the top onto the ground surface, and a pressure girder 6 disposed above the caisson housing 1 are provided. The jack 7 mounted on the upper portion of the pressure girder 6 and attached to the top of the earth anchor 5... And the bearing plate 8 interposed between the caisson housing 1 and the pressure girder 6. There is something. The earth anchor 5 has a configuration in which a fixing portion (ground anchor 10) is attached to the lower end of a tensile material (tension rod 9), and is disposed around the caisson housing 1. The jack 7 is a machine that expands and contracts in a vertical direction while being fixed to the upper portion of the earth anchor 5. For example, a grip jack that holds the upper portion of the earth anchor 5 can be used. The pressure girder 6 is made of, for example, a steel material such as an H-shaped steel, and the jacks 7 are respectively placed on both ends of the pressure girder 6 projecting to the side of the caisson housing 1.

  The excavator 3 described above is a machine that is disposed inside the caisson housing 1 and excavates the ground G in the vertical direction. For example, the casing 11 and a plurality of excavating blades 12 provided at the lower end of the casing 11 There is a configuration that includes a drive mechanism 13 that rotates the casing 11. The casing 11 is a cylindrical body that is inserted into the caisson housing 1. The upper and lower ends are opened, and a plurality of excavation bits 14 for excavating the ground G are attached to the lower end of the casing 11. Yes. The excavation blade 12 is a plate-like member that is vertically raised and projects laterally from the outer peripheral surface of the casing 11, and a plurality of excavation bits 15 for excavating the ground G at the lower end thereof. Is attached. The excavated earth and sand generated by excavation by the excavating blades 12 are taken into the casing 11 from the intake ports 11a formed in the casing 11.

  The excavator 3 is a machine that can freely expand and contract the excavation diameter. For example, the tip of the excavation blade 12 can be folded. Specifically, the excavating blade 12 includes a fixed blade 16 protruding from the outer peripheral surface of the casing 11, an enlarged fixed blade 17 attached to the tip of the fixed blade 16, and a tip of the enlarged fixed blade 17 in the horizontal direction. The movable wing 18 is rotatably mounted, and a cylinder (rotating mechanism) 19 that rotates the movable wing 18 in the horizontal direction to store or project the movable wing 18.

  The unloading facility 4 is an facility for carrying out excavated earth and sand in the caisson housing 1 and has a configuration in which the hammaglab 20 is suspended by a lifting machine (not shown) such as a crane. Specifically, the hammag rub 20 is suspended in the casing 11 described above, the excavated earth and sand in the casing 11 is grasped by the hammag lab 20, and the hammag lab 20 is lifted as it is to carry out the excavated earth and sand.

FIG. 3 is a block diagram showing the caisson settlement management system in the present embodiment.
As shown in FIGS. 1 and 3, the construction system for performing the caisson method according to the present invention includes a caisson settlement management system for managing the settlement of the caisson housing 1. The caisson settlement management system includes a caisson monitoring system 21 that monitors the inclination and settlement amount of the caisson housing 1 and the load introduced by the press-fitting device 2, the excavator 3 and the excavation depth and excavation by the excavator 3. An excavator management system 22 for changing the diameter and a stress observation system 23 for observing the stress in the caisson housing 1 are provided.

  As the caisson monitoring system 21, a known caisson monitoring system can be adopted. For example, an inclinometer 24 for measuring the amount of inclination of the caisson housing 1, a settlement meter 25 for measuring the amount of settlement of the caisson housing 1, and press-fitting There is a system that includes a load cell 26 that measures the magnitude of the load introduced by the apparatus 2. As the inclinometer 24, the settlement meter 25, and the load meter 26, known instruments can be used, respectively, and the inclinometer 24, the settlement meter 25, and the load meter 26 are known automatic measuring instruments (first meter). Each is connected to an automatic measuring instrument 27).

  As the excavator management system 22, a known excavator management system can be adopted. For example, a rotation speed meter 28 that measures the rotation speed of the excavator 3 and a settlement speed meter that measures the settlement speed of the excavator 3. 29 and a torque meter 30 that measures the torque of the excavator 3. As the rotation speed meter 28, the settlement speed meter 29, and the torque meter 30, known instruments can be used, respectively, and the rotation speed meter 28, the settlement speed meter 29, and the torque meter 30 are the first automatic speed meter. Each is connected to a measuring instrument 27.

  The stress observation system 23 is a system that measures the stress in the caisson housing 1 using a strain gauge 31 that is installed in the caisson housing 1 and measures the strain (vertical stress) of the caisson housing 1. The internal stress of the caisson housing 1 is calculated by multiplying the vertical stress thus applied by the horizontal sectional area of the caisson housing 1. For example, the stress observation system 23 is provided with a plurality of known strain gauges 31 for measuring the strain of the caisson housing 1, and the strain gauge 31 is connected to a known automatic measuring instrument (second instrument) via a joint box 33. It is connected to an automatic measuring instrument 32).

  The first automatic measuring instrument 27 is connected to the monitoring personal computer 34, and the second automatic measuring instrument 32 is connected to the collecting personal computer 35. The monitoring personal computer 34 and the collection personal computer 35 are connected, and measurement is performed between the stress observation system 23 and the caisson monitoring system 21 and between the stress observation system 23 and the excavator monitoring system 22. Data is linked (linked).

FIG. 4 shows a monitor screen 36 in the caisson settlement management system.
As shown in FIG. 4, the monitoring personal computer 34 and the collection personal computer 35 are connected to a monitor screen 36, respectively, and observation data in the caisson settlement management system is monitored in real time by the monitor screen 36. Can do. Reference numeral 37 shown in FIG. 4 represents the progress of caisson settlement. Further, the observed moment 38 is digitally displayed at the reference numeral 38 shown in FIG. Further, reference numeral 39 shown in FIG. 4 is a display column for the observed housing stress, and reference numeral 40 shown in FIG. 4 is a display column for the currently set tip ground resistance force. Reference numeral 41 indicates a display field for a currently set peripheral friction set value. Further, reference numeral 42 shown in FIG. 4 is an excavation depth input field, and reference numeral 43 shown in FIG. 4 is an excavation diameter input field. Also, reference numeral 44 shown in FIG. 4 is a correction value input field to be described later, and displays the currently set correction value. The monitor screen 36 having the above display is automatically updated in real time, and the observation data is automatically stored in the hard disk. It should be noted that by setting an alarm value, an alarm may be output when the observed stress in the enclosure falls below a certain level.

FIG. 5 is a cross-sectional view taken along the line AA shown in FIG.
As shown in FIGS. 2 and 5, it is preferable that the strain gauge 31 described above is disposed on the upper portion of the blade edge 1 a inside the caisson housing 1. In the present embodiment, a plurality of strain gauges 31 are installed at the lower end of the second lot 50b installed on the first lot 50a. For example, when measuring the stress in the housing with a blade edge reaction force meter, in order to install the blade edge reaction force meter vertically on the blade edge 1a, the blade edge 1a is cut out to form a hole, and a jig is used for the hole. A blade edge reaction force meter will be attached. In this case, there is a possibility that soil particles will be clogged by clogging the hole where the blade edge reaction force meter is installed. On the other hand, as described above, by installing the strain gauge 31 above the blade edge 1a in the caisson housing 1, instrument troubles such as clogging do not occur.

  Moreover, it is preferable that the strain gauges 31 are respectively installed at the measurement position of the inclination measurement. In this embodiment, the strain gauges 31 are arranged at four measurement points in the inclination measurement direction. This is in consideration of the unevenness of the ground G and the variation in the ground reaction force caused by the inclination of the caisson housing 1, and by arranging the strain gauges 31 at the measuring points in the inclination measuring direction, The behavior can be examined in association.

  Moreover, it is preferable that the strain gauges 31 are installed in pairs of the inside and outside of the caisson housing 1. In the present embodiment, the strain gauges 31 are respectively installed on the inner side and the outer side at four measurement points in the tilt measurement direction. Thereby, the bending distortion which generate | occur | produces in a housing at the time of caisson housing 1 installation can be canceled.

FIG. 6 is an enlarged cross-sectional view of the upper portion of the blade opening 1 a of the caisson housing 1.
The strain gauge 31 described above can be installed in the caisson housing 1 by various methods. For example, as shown in FIG. 6, between the two structural reinforcing bars 34, 34 extending in the vertical direction, An installation rebar 35 is installed, dedicated hubs 36 and 36 are joined to the installation rebar 35, and strain gauges 31 and 31 are attached to lower ends of mounting rods 37 and 37 suspended from the dedicated hubs 36 and 36. Can do.

  FIG. 7 is a flowchart of the caisson settlement method in the present embodiment, and FIGS. 8 to 11 are cross-sectional views showing the steps of the caisson settlement method in the present embodiment. 8 and 11, the excavator 3 and the earthing equipment 4 are not shown.

  In the caisson settlement method according to the present embodiment, first, as shown in FIGS. 7 and 8, a basic data collecting step of collecting basic data of the ground G in addition to the caisson housing is performed. Specifically, the caisson housing 1 is press-fitted into the ground G by the press-fitting device 2 without using the excavator 3 shown in FIG. That is, the plurality of jacks 7 of the press-fitting device 2 are extended to press the pressure girder 6 downward, and a downward introduction load is applied from the pressure girder 6 to the caisson housing 1 through the bearing plate 8.

At this time, the caisson monitoring system 21 shown in FIG. 3 performs press-fitting while constantly monitoring the attitude of the caisson housing 1. Specifically, as shown in FIG. 3, the inclination of the caisson housing 1 is monitored with the data from the inclinometer 24, the amount of subsidence of the caisson housing 1 is monitored with the data from the subsidometer 25, and the load meter 26 Monitor that the load on jacks 7 ... does not exceed the design value.
Further, the state of the excavator 3 is constantly monitored by the excavator monitoring system 22 shown in FIG. Specifically, as shown in FIG. 3, it is monitored that the excavator 3 is not moving based on data from the rotation speed meter 28, the settlement speed meter 29 and the torque meter 30.

  Further, the stress in the caisson housing 1 is constantly observed by the stress observation system 23 shown in FIG. 3, and the time when the caisson housing 1 starts to subside is detected by the settlement meter 25 and the load meter 26 of the caisson monitoring system 21 shown in FIG. Then, the stress in the casing when the caisson casing 1 starts to sink is detected. The stress in the housing is calculated by measuring the vertical stress by the strain gauges 31 of the stress observation system 23 and multiplying the measured vertical stress by the horizontal cross-sectional area of the caisson housing 1. Also, at the moment when the caisson housing 1 sinks, the subsidence meter 25 starts to move, and the load meter 26 decreases momentarily. Therefore, by detecting this change, the time when the caisson housing 1 starts to sink is detected.

  By the way, since the stress in the casing at the start of subsidence of the caisson casing 1 is substantially equal to the tip ground resistance force, the value of the stress in the casing at the start of subsidence of the caisson casing 1 is calculated as the blade of the caisson casing 1. It can be seen as the current tip ground resistance acting on the mouth 1a. Therefore, the value of the body stress detected at the start of the settlement of the caisson housing 1 is used as the tip ground resistance force, and a correction value for correcting the set value of the tip ground resistance force is obtained. Specifically, the correction value is obtained from the difference between the detected stress in the casing at the start of the caisson housing subsidence and the set value of the currently set tip ground resistance force.

  Next, as shown in FIG. 7 and FIG. 9, the set value of the tip ground resistance force is corrected with the correction value described above, and the excavation depth H and the excavation diameter D in the excavation process are set based on the corrected set value, respectively. The adjustment process is performed. Specifically, the correction value is input to the correction value input field 44 of the monitor screen 36 shown in FIG. 4 to correct the set value of the tip ground resistance force. The corrected set value of the tip ground resistance can be confirmed in the tip ground resistance column 40 of the monitor screen 36 shown in FIG. Thereafter, based on the corrected new setting values, the setting values of the excavation depth H and the excavation diameter D are respectively input to the excavation depth input field 42 and the excavation diameter input field 43 of the monitor screen 36 shown in FIG. The excavation depth H and excavation diameter D by the excavator 3 are set. The excavation depth H is the depth of excavation by the excavator 3 shown in FIG. 1 and is adjusted by controlling the driving of the excavator 3. The excavation diameter D is an excavation diameter by the excavator 3 shown in FIG. 1, and is adjusted by folding the movable blade 18 to an appropriate position by the cylinder 19.

  Next, as shown in FIGS. 1, 7, and 10, an excavation process for excavating the ground G from the inside of the tubular caisson housing 1 is performed. Specifically, first, the drive mechanism 13 of the excavator 3 disposed in the caisson housing 1 is operated to rotate the casing 11, and provided at the lower end portion of the casing 11 and the lower end portion of the excavation blade 12. The ground G is excavated by the excavation bits 14. In this excavation process, excavation is performed at an excavation depth and an excavation diameter set based on the set value of the tip ground resistance force. That is, when the excavation is performed to the set excavation depth, the drive mechanism 13 is stopped and the excavation by the excavator 3 is stopped. Further, before starting excavation, the movable blade 18 is rotated by the cylinder 19 and the tip of the excavation blade 12 is folded and adjusted so that excavation is performed with the set excavation diameter.

Further, during the excavation process described above, the caisson housing 1 is constantly monitored by the caisson monitoring system 21 shown in FIG. That is, as shown in FIG. 3, it is confirmed whether there is any change in the data from the inclinometer 24 or the subsidometer 25, and it is monitored whether the caisson housing 1 is moving. When it is confirmed that the data from the inclinometer 24 or the subsidometer 25 has changed and the caisson housing 1 has moved, the driving of the excavator 3 is temporarily stopped, and the excavation depth and the excavation diameter are changed. Make a change.
Further, the movement of the excavator 3 is constantly monitored by the excavator monitoring system 22 shown in FIG. That is, as shown in FIG. 3, it is monitored whether the excavator 3 is driven as set by data from the rotation speed meter 28, the settlement speed meter 29, and the torque meter 30.
Furthermore, the state of the ground G is constantly monitored by the stress observation system 23 shown in FIG. That is, as shown in FIG. 3, the stress in the enclosure is constantly observed by the strain gauge 31, the observed data is compared with the set tip ground resistance, and whether or not unequal settlement occurs in the ground G To monitor.

  Further, as shown in FIG. 1, excavated earth and sand generated by excavation by the excavator 3 are taken into the casing 11 from the lower end of the opened casing 11 and the intake ports 11 a of the casing 11. The earth and sand taken into the casing 11 is carried out of the casing 11 by the earthing equipment 4. That is, the hanger mag 20 is suspended in the casing 11, and the excavated earth and sand in the casing 11 is grasped by the hamma magnet 20. Then, the hammaglab 20 is transported to a temporary storage yard or a loading platform of the unloading vehicle in the field, where the hammaglab 20 is opened to spread excavated soil.

  Next, as shown in FIGS. 7 and 11, a press-in process is performed in which a downward introduction load is applied to the caisson housing 1 to cause the caisson housing 1 to sink into the ground G by its own weight and the introduction load. Specifically, a downward introduction load is applied to the caisson housing 1 by applying a downward pressing force to the caisson housing 1 by the jacks 7 extending and contracting in the vertical direction. That is, the plurality of jacks 7 of the press-fitting device 2 are extended to press the pressure girder 6 downward, and a downward introduction load is applied from the pressure girder 6 to the caisson housing 1 through the bearing plate 8.

  At this time, the attitude of the caisson housing 1 is constantly monitored by the caisson monitoring system 21 shown in FIG. 3 and the excavator shown in FIG. 1 by the excavator monitoring system 22 shown in FIG. The state of 3 is constantly monitored.

  Further, the stress in the caisson housing 1 is constantly observed by the stress observation system 23 shown in FIG. 3, and the time when the caisson housing 1 starts to subside is detected by the settlement meter 25 and the load meter 26 of the caisson monitoring system 21 shown in FIG. Then, the stress in the casing when the caisson casing 1 starts to sink is detected. Then, using the detected value of the stress in the housing as the current tip ground resistance force, a correction value for correcting the set value is obtained. The stress in the housing is calculated in the same manner as in the basic data collection process described above. Further, when the caisson housing 1 starts to sink, it is detected in the same manner as in the basic data collection step described above. The correction value is a value for correcting the currently set tip ground resistance to the detected current tip ground resistance (internal stress), and is obtained from the difference between the two tip ground resistances.

  Further, the detection of the stress in the housing at the start of the settlement is performed every time the jacks 7... Are updated, and the above correction value is updated every stroke of the jacks 7. That is, until the caisson housing 1 reaches a predetermined depth, the press-fitting of the caisson housing 1 by the jacks 7 and the correction value correction (review) are repeated.

  Next, as shown in FIGS. 7 and 9, the set value of the tip ground resistance force is corrected with the correction value described above, and the excavation depth H and the excavation diameter in the next excavation process are corrected based on the new set value after correction. An adjusting step for adjusting D is performed. Specifically, the correction value described above is re-entered in the correction value input field 44 of the monitor screen 36 shown in FIG. 4, and the current setting value of the tip ground resistance is corrected with the correction value. The set value is changed to a value corresponding to the detected stress in the enclosure. The corrected set value of the tip ground resistance can be confirmed in the tip ground resistance column 40 of the monitor screen 36 shown in FIG. Thereafter, based on the corrected new set values, the new set values of the drilling depth H and the drilling diameter D are re-entered in the drilling depth input field 42 and the drilling diameter input field 43 shown in FIG. The excavation depth H and the excavation diameter D are adjusted by the machine 3. The excavation depth H and the excavation diameter D are adjusted in the same manner as in the previous adjustment step.

Thereafter, as shown in FIG. 7, the above-described excavation process is performed again with the newly set new excavation depth and diameter, and then the above-described press-fitting process is performed again. That is, the above-described adjustment process, excavation process, and press-fitting process are sequentially repeated to sink the caisson housing 1 to a predetermined depth.
Then, after the caisson housing 1 is set up by the caisson housing method, the lot 50 shown in FIG. 2 is installed at the upper end of the caisson housing 1 to construct the caisson housing 1. Then, after the addition of the caisson housing 1 is completed, the above-described caisson settlement method adjustment process, excavation step, and press-fitting step are sequentially repeated to sink the caisson housing 1 to a predetermined depth.

  Next, the stress acting on the caisson housing 1 will be described.

  FIG. 12 is a schematic diagram showing the stress relationship at the time of caisson housing construction, FIG. 13 is a schematic diagram showing the stress relationship before the caisson housing subsidence in the press-fitting process, and FIG. FIG. 15 is a schematic diagram showing the stress relationship during caisson housing settlement in the press-fitting process.

  As shown in FIG. 12, when the caisson housing 1 is constructed, no introduction load is applied to the caisson housing 1, and the caisson housing 1 is stationary. The relational expression of stress in this state is as the following expression (Expression 1).

  Further, the housing stress W1 in this case is expressed by the following formula (Formula 2).

  Therefore, according to the above two formulas (Formula 1 and Formula 2), the relationship between the tip ground resistance force W2 and the internal stress W1 is expressed by the following formula (Formula 3).

  In other words, the housing stress W1 in this case is smaller than the tip ground resistance force W2, and the caisson housing 1 is supported by the circumferential friction force F and the ground reaction force and does not sink.

  Moreover, as shown in FIG. 13, before the caisson housing 1 sinks in the press-fitting process, an introduction load is applied to the caisson housing 1 and the caisson housing 1 is stationary. The relational expression of stress in this state is as shown in the following expression (Expression 4).

  Further, the housing stress W1 in this case is expressed by the following formula (Formula 5).

  Therefore, according to the above two formulas (Formula 4 and Formula 5), the relationship between the tip ground resistance force W2 and the housing stress W1 is expressed by the following formula (Formula 6).

  In other words, the housing stress W1 in this case increases by the introduction load P, but is smaller than the tip ground resistance force W2, and the caisson housing 1 is supported by the circumferential friction force F and the ground reaction force so as not to sink. It has become.

  Subsequently, as shown in FIG. 14, when the introduction load P applied to the caisson enclosure 1 is increased, the enclosure stress W1 also increases in proportion to the introduction load P, and the excavation part of the ground G starts to collapse diagonally. The caisson housing 1 begins to sink. The relational expression of the stress at the time when the caisson housing 1 starts to sink, that is, at the moment when the caisson housing 1 sinks is expressed by the following equation (Equation 7).

  Accordingly, the relationship between the tip ground resistance force W2 and the housing stress W1 at this time is expressed by the following equation (Equation 8).

  Then, as shown in FIG. 15, when the introduction load P applied to the caisson housing 1 is further increased, the relational expression of stress becomes the following expression (Expression 9).

  Therefore, the relationship between the tip ground resistance force W2 and the housing stress W1 at this time is expressed by the following equation (Equation 10).

  Thus, the internal stress W1 at the start of the settlement of the caisson housing 1 is substantially equal to the tip ground resistance W2, and the caisson housing 1 sinks when the housing stress W1 exceeds the tip ground resistance W2.

  In the caisson settlement method constructed as described above, in the excavation process, excavation is performed at an excavation depth and an excavation diameter set based on the set value of the tip ground resistance force. Further, in the press-fitting process, the sinking gauge 25 and the load meter 26 detect when the caisson casing 1 starts to sink, detect the stress in the caisson casing 1 when the caisson casing 1 starts to be detected, and detect the stress in the casing. As the ground resistance, a correction value of the set value of the tip ground resistance described above is obtained. Then, after the press-fitting step, an adjustment step of correcting the set value of the tip ground resistance force with the correction value and adjusting the excavation depth and the excavation diameter in the next excavation step based on the new set value after the correction. Is going. According to the caisson settlement method having such a configuration, the set value of the tip ground resistance force for setting the next excavation depth and excavation diameter is corrected based on the measured stress in the enclosure. This is because at the moment when the caisson housing 1 sinks, the stress in the housing of the caisson housing 1 and the tip ground resistance force (blade edge reaction force) are substantially equal to each other. It is because it can be seen as the tip ground resistance. That is, since the set value in the next excavation is corrected based on the current tip ground resistance, the next excavation depth and the excavation diameter are changed in accordance with the actual field situation. Thereby, the excavation depth and the excavation diameter can be adjusted so that the caisson housing 1 does not settle down, and the caisson housing 1 can be prevented from being oversunk. Thus, by preventing self-sinking of the caisson housing 1, it is possible to prevent the excavating blades 12 of the excavator 3 from being sandwiched between the caisson housings 1 and being unable to excavate. Note that, at the moment when the caisson housing 1 begins to sink, the settlement meter 25 starts to move, and the value of the load meter 26 decreases momentarily, so the time when the caisson housing 1 starts to sink from the settlement meter 25 or the load meter 26 is displayed. It is possible to detect.

  Further, in the caisson settlement method having the above-described structure, the stress in the enclosure is measured by measuring the vertical stress generated in the caisson enclosure 1 with a strain gauge 31 installed in the caisson enclosure 1, and the caisson enclosure is measured to the measured vertical stress. It is calculated by multiplying by 1 horizontal cross section. With such a configuration, not the biased ground reaction force as measured by the blade edge reaction force meter or the like, but the ground reaction force received by the entire blade edge 1a is calculated, and the ground reaction force received by the entire blade edge 1a is calculated. Observed. Thereby, even when the ground reaction force acting on the blade edge 1a of the caisson housing 1 is uneven due to the geology and shape of the ground, the accurate tip ground resistance force is grasped, and the caisson housing 1 is surely self-sunk. The excavation depth and the excavation diameter can be adjusted so that the caisson housing 1 can be reliably prevented from being oversunk.

  Further, in the caisson settlement method having the above-described configuration, an introductory load is applied to the caisson housing 1 by applying a downward pressing force to the caisson housing 1 by the jacks 7 that extend in the vertical direction. For each stroke of the jacks 7..., The correction value is updated by detecting the stress in the casing of the caisson casing 1 at the start of subsidence. Thus, by detecting the internal stress for each stroke of the jack 7 ..., the internal stress (ground reaction force) closer to the tip ground resistance force at the start of the next press-fitting process is detected, and more An accurate correction value is obtained. Thereby, it can adjust to the excavation depth and excavation diameter in which the self-sink of the caisson housing 1 does not produce reliably, and the oversinking of the caisson housing 1 can be prevented reliably.

  Further, according to the caisson settlement management system having the above-described configuration, the caisson monitoring system 21 having the settlement meter 25 and the load meter 26, the excavator 3 is monitored, and the excavation depth and the diameter of the excavator 3 are changed. Since the machine management system 22 and the stress observation system 23 for observing the stress in the caisson housing 1 are provided, the caisson monitoring system 21 grasps the movement and the introduction load of the caisson housing 1, and also monitors the caisson. The subsidence meter 25 and the load meter 26 provided in the system 21 detect the start of subsidence of the caisson housing 1. Further, the stress observation system 23 observes the stress in the caisson housing 1 and detects the stress in the housing at the start of the settlement. Further, the excavator management system 22 grasps the state and movement of the excavator 3 during the excavation process and the press-fitting process, and adjusts the excavation depth and the excavation diameter based on the new set values corrected by the correction values. The Thereby, the above-described caisson settlement method can be implemented, and the effects of the above-described caisson settlement method can be achieved.

  As mentioned above, although the embodiment of the caisson settlement method and the caisson settlement management system according to the present invention has been described, the present invention is not limited to the above embodiment, and can be appropriately changed without departing from the scope of the present invention. is there. For example, in the above-described embodiment, the case where the reinforced concrete caisson housing 1 is set up is described. However, the present invention may be a caisson housing other than the reinforced concrete, for example, a steel caisson housing. It may be, or it may be a caisson housing composed of a combination of a steel plate and concrete.

  Further, in the above-described embodiment, after the basic data collection process is performed first, the excavation process, the press-fitting process, and the adjustment process are sequentially performed. However, in the present invention, the basic data is collected in advance. The basic data collection process may be omitted and the excavation process may be started.

In the above-described embodiment, the caisson monitoring system 21 includes the inclinometer 24, the settlement meter 25, and the load meter 26. However, in the present invention, the caisson monitoring system does not include the inclinometer. Alternatively, the caisson monitoring system may have only one of the squat meter or load meter and not the other.
In the embodiment described above, the caisson housing 1 is detected by both the settlement meter 25 and the load meter 26 when the caisson housing 1 starts to sink. However, in the present invention, the caisson housing is detected by either the settlement meter or the load meter. You may detect the time of the start of sinking.

  Further, in the above-described embodiment, the excavation depth and the excavation diameter in the next excavation process are adjusted based on the set value of the new tip ground resistance force corrected by the correction value. Only the digging diameter may be adjusted without adjusting the digging depth based on the new setting value described above, or only the digging depth may be adjusted without adjusting the digging diameter based on the new setting value described above. May be.

  Further, in the above-described embodiment, the vertical stress generated in the caisson housing 1 is measured by the strain gauge 31..., And the stress in the housing is calculated by multiplying the measured vertical stress by the horizontal sectional area of the caisson housing 1. However, in the present invention, the stress in the casing of the caisson casing 1 may be detected by other means or instruments. In the above-described embodiment, a plurality of strain gauges 31 are provided, but the present invention may include only one strain gauge.

  In the above-described embodiment, the downward introduction load is applied to the caisson housing 1 by the press-fitting device 2 including the jacks 7..., But the present invention applies the downward introduction load to the caisson housing by other methods. For example, the introduction load may be applied to the caisson housing by a method of placing a load on the caisson housing.

  In the above-described embodiment, the correction value is updated by detecting the stress in the casing of the caisson casing 1 at the start of subsidence for each stroke of the jacks 7... The stress in the housing need not be detected, and the correction value need not be updated for each stroke of the jack. For example, the correction value may be obtained by detecting only the stress in the housing at the time of the final press-fitting operation in the press-fitting process, or the correction value is not updated for detecting the stress in the housing for each stroke of the jack, The correction value may be corrected based on the stress in the housing during the last jack stroke in the press-fitting process.

  In the above-described embodiment, the open caisson method is adopted, but the present invention can adopt a pneumatic caisson method. For example, when digging with soft caisson in the pneumatic caisson method, since the ground reaction force is small, support force is applied to prevent excessive subsidence and inclination by forming a bladed sanddle or leaving soil in the work chamber. The opening ratio is examined in consideration of ground strength (reaction force) at the time of design. In soft ground where the tip ground resistance is small, the aperture ratio is generally small, and the space in the work chamber is narrowed. If the space in this working room becomes too small, it becomes impossible to perform construction, or it becomes difficult to ensure the safety of workers. On the other hand, by attaching a strain gauge to the upper part of the blade edge of the caisson housing, the ground resistance at the tip is estimated, and this is used as a judgment material when determining the unexposed width in the construction work, and is set to the optimum aperture ratio. It is possible to improve the safety of construction.

  Further, by measuring the stress in the caisson housing at a plurality of points in a plane and measuring and managing the difference at each point, it is possible to infer the existence of an inclined stratum or an obstacle. Therefore, an excessive inclination of the caisson housing due to the difference in the tip ground resistance force can be prevented by setting the difference in the amount of uncut digging in plan according to the difference in the tip ground resistance force.

  In addition, in the range which does not deviate from the main point of this invention, it is possible to replace suitably the component in above-mentioned embodiment with a well-known component, and you may combine the above-mentioned modification suitably.

It is sectional drawing showing the construction system of the caisson settlement method for demonstrating embodiment of this invention. It is an elevation sectional view showing the caisson housing for explaining an embodiment of the invention. It is a block diagram showing the caisson settlement management system for demonstrating embodiment of this invention. It is a figure showing the monitor screen of the caisson settlement management system for demonstrating embodiment of this invention. FIG. 3 is a cross-sectional plan view of a caisson housing for explaining an embodiment of the present invention, and is a cross-sectional view taken along A-A shown in FIG. 2. It is an expanded sectional view of the blade mouth upper part of the caisson housing for demonstrating embodiment of this invention. It is a flowchart figure of the caisson settlement method for demonstrating embodiment of this invention. It is sectional drawing showing the basic data collection process in the caisson settlement method for demonstrating embodiment of this invention. It is sectional drawing showing the adjustment process in the caisson settlement method for demonstrating embodiment of this invention. It is sectional drawing showing the excavation process in the caisson settlement method for demonstrating embodiment of this invention. It is sectional drawing showing the press injection process in the caisson settlement method for demonstrating embodiment of this invention. It is the schematic diagram showing the stress relationship at the time of caisson housing construction for demonstrating embodiment of this invention. It is the schematic diagram showing the stress relationship before the caisson housing subsidence in the press-fit process for demonstrating embodiment of this invention. It is the schematic diagram showing the stress relationship at the time of the caisson housing subsidence start in the press-fitting process for demonstrating embodiment of this invention. It is the schematic diagram showing the stress relationship in the caisson body subsidence in the press-fit process for demonstrating embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Caisson frame 1a Cutting edge 3 Excavator 7 Jack 21 Caisson monitoring system 22 Excavator management system 23 Stress observation system 25 Subsidence meter 26 Load meter 31 Strain meter D Excavation diameter G Ground H Excavation depth P Introduction load W1 Internal body stress W2 Tip Ground resistance ΣW The weight of the caisson enclosure

Claims (4)

A caisson comprising: a drilling step of excavating the ground from the inside of the caisson housing; and a press-fitting step of applying a downward introduction load to the caisson housing to sink the caisson housing into the ground by the weight of the caisson housing and the introduced load. A subsidence method,
In the excavation step, excavation at the excavation depth and excavation diameter set based on the set value of the tip ground resistance force acting on the blade edge of the caisson housing,
In the press-fitting step, one or both of a settlement meter for measuring the amount of settlement of the caisson housing and a load meter for measuring the magnitude of the introduced load is used to detect when the caisson housing starts to sink and to detect The internal stress of the caisson housing at the start of subsidence is detected, and the stress in the caisson housing is detected as the tip ground resistance force, and the value of the internal stress at the start of subsidence of the caisson housing and the excavation process A correction value for the set value is obtained from the difference from the set value,
After the press-fitting step, the set value is corrected with the correction value so that the set value of the tip ground resistance force is changed to a value corresponding to the detected value of the stress in the housing, and a new set value after correction A caisson settlement method characterized by performing an adjustment step of adjusting one or both of a drilling depth and a drilling diameter in the next drilling step based on the above. In the caisson settlement method according to claim 1,
The stress in the enclosure is calculated by measuring the vertical stress generated in the caisson enclosure with a strain gauge installed in the caisson enclosure and multiplying the measured vertical stress by the horizontal cross-sectional area of the caisson enclosure. The caisson settlement method. In the caisson settlement method according to claim 1 or 2,
The introduction load is applied to the caisson housing by applying a downward pressing force to the caisson housing with a jack that extends vertically.
A caisson settlement method for detecting the stress in the casing of the caisson housing at the start of settlement for each stroke of the jack and updating the correction value. A caisson comprising: a drilling step of excavating the ground from the inside of the caisson housing; and a press-fitting step of applying a downward introduction load to the caisson housing to sink the caisson housing into the ground by the weight of the caisson housing and the introduced load. In the caisson settlement management system in the settlement method,
A caisson monitoring system having one or both of a settlement meter for measuring the amount of settlement of the caisson housing and a load meter for measuring the magnitude of the introduction load;
The excavator performing the excavation process is monitored, and one or both of the excavation depth and the excavation diameter by the excavator is changed based on a set value of a tip ground resistance force acting on a blade edge of the caisson housing. Excavator management system to
In order to obtain a correction value for correcting the set value in the next excavation step from the difference between the stress value in the case at the start of subsidence of the caisson case and the set value in the previous excavation step, A caisson settlement management system, comprising: a stress observation system disposed immediately above the blade edge and observing the stress in the housing immediately above the blade edge of the caisson housing.

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