Specific gravity measuring device

Abstract

To provide a specific gravity measurement device capable of measuring specific gravity of a suspension liquid with a simple configuration without measuring the depth of a measurement point.SOLUTION: A specific gravity measurement device 1 for measuring specific gravity of a suspension liquid includes: an upper water pressure gauge 13 for measuring a water pressure of the suspension liquid; a lower water pressure gauge 14 for measuring the water pressure of the suspension liquid at a deeper depth than in the upper water pressure gauge 13; a water pressure gauge arrangement mechanism for arranging the upper and lower water pressure gauges 13, 14 at upper and lower positions in a vertical direction at a predetermined measurement interval d; and a collection part for collecting a measurement value of each of the upper and lower water pressure gauges 13, 14 at the same timing.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a specific gravity measuring device for measuring the specific gravity of a suspension such as deposited muddy water.

Background Art

[0002] In a construction method of drilling the ground using muddy water, in order to grasp the properties of the muddy water deposited in the drilled holes or trenches, the specific gravity is measured. Also, in a construction method of improving the ground in situ, the specific gravity is measured in order to grasp the properties and the formed shape of soil-cement columns. Further, in the method of placing in-situ concrete piles, in order to grasp the properties of the muddy water poured into the drilled holes to protect the hole walls, the specific gravity is measured.

[0003] When measuring the specific gravity with a measuring device (such as a mud balance) installed on the ground, the sampling operation of the suspension to be measured is complicated and requires a lot of time. Therefore, a measuring device for measuring the specific gravity of a suspension in situ in the ground has been proposed (see, for example, Patent Documents 1 and 2).

[0004] In Patent Documents 1 and 2, the specific gravity of the suspension is measured by measuring the differential pressure between two points above and below across the depth to be measured.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in Patent Document 1, a complicated operation of measuring the depth of the measurement position using a graduated rope is required. And depending on the water surface position of the suspension, it is impossible to grasp the water surface from the ground, and it is difficult to measure the depth of the measurement position itself. Further, in Patent Document 2, a complicated mechanism such as a communicating pipe for measuring the hydrostatic pressure is required.

[0007] The present invention has been made in view of such circumstances, and an object thereof is to provide a specific gravity measuring device that solves the above-described problems and can measure the specific gravity of a suspension with a simple configuration without measuring the depth of the measurement position.

Means for Solving the Problems

[0008] The specific gravity measuring device of the present invention is a specific gravity measuring device for measuring the specific gravity of a suspension, and includes an upper water pressure gauge for measuring the water pressure of the suspension, a lower water pressure gauge for measuring the water pressure of the suspension at a depth deeper than the upper water pressure gauge, a water pressure gauge arrangement mechanism for arranging the upper water pressure gauge and the lower water pressure gauge at a preset measurement interval in the vertical up-and-down position, and a collection unit for collecting the measurement values of the upper water pressure gauge and the lower water pressure gauge at the same timing. Moreover, the pressure gauge arrangement mechanism of the upper pressure gauge and the lower pressure gauge is provided with an intermediate pressure gauge that is vertically movably attached and measures the water pressure at a depth between the upper pressure gauge and the lower pressure gauge, and the collection unit collects the measured values of the upper pressure gauge, the lower pressure gauge, and the intermediate pressure gauge at the same timing. It is characterized by this. Furthermore, in the specific gravity measuring device of the present invention, the water pressure gauge arrangement mechanism may be a towing body with a weight attached to one end, and may be attached to the towing body at the measurement interval. Furthermore, in the specific gravity measuring device of the present invention, the water pressure gauge arrangement mechanism may be a rod with one end attached to a towing body, and may be attached to the rod at the measurement interval. Furthermore, the specific gravity measuring device of the present invention may include a specific gravity calculation unit that calculates the average specific gravity at the intermediate point between the upper water pressure gauge and the lower water pressure gauge using the measurement values of the upper water pressure gauge and the lower water pressure gauge, a depth calculation unit that calculates the depth from the water surface at the intermediate point between the upper water pressure gauge and the lower water pressure gauge as the intermediate depth using the measurement values of the upper water pressure gauge and the lower water pressure gauge, and an output unit that outputs the average specific gravity calculated by the specific gravity calculation unit and the intermediate depth calculated by the depth calculation unit. 。

Advantages of the Invention

[0009] According to the present invention, by using the measurement result, a known measurement interval, and the acceleration due to gravity, the specific gravity and the intermediate depth at the intermediate point between the upper piezometer and the lower piezometer can be calculated. Therefore, the specific gravity of the suspension can be measured with a simple configuration without measuring the depth of the measurement position, which has the effect of being able to measure the specific gravity of the suspension with a simple configuration without measuring the depth of the measurement position.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0011] Next, modes for carrying out the present invention (hereinafter simply referred to as "embodiments") will be specifically described with reference to the drawings.

[0012] (First Embodiment) The specific gravity measuring device 1 of the first embodiment is a device for measuring the specific gravity of a suspension such as sedimented muddy water. Referring to FIG. 1, it includes a towing body 11 such as a rope or a tape, a weight 12 attached to one end of the towing body 11, an upper piezometer 13 and a lower piezometer 14 attached to the towing body 11, and a specific gravity calculation device 20 that calculates the specific gravity using the water pressures measured by the upper piezometer 13 and the lower piezometer 14.

[0013] The weight 12 is made of a material having a specific gravity sufficiently greater than that of the suspension to be measured (for example, a metal such as iron) so that the direction of the towing body 11 is vertical while being suspended in the suspension by the towing body 11.

[0014] The upper water pressure gauge 13 and the lower water pressure gauge 14 measure the water pressure P of the suspension liquid 上 , the water pressure P 下 respectively. As the upper water pressure gauge 13 and the lower water pressure gauge 14, for example, a pore water pressure gauge that measures the pressure by the pore water contained in the soil, a pressure gauge for measuring the pressure of a liquid, etc. can be used.

[0015] The upper water pressure gauge 13 and the lower water pressure gauge 14 are attached to the towing body 11 at intervals of a preset measurement interval d. Thereby, the towing body 11 with the weight 12 attached to one end functions as a water pressure gauge arrangement mechanism that arranges the upper water pressure gauge 13 and the lower water pressure gauge 14 suspended by the towing body 11 at preset measurement intervals d in the vertical upper and lower positions.

[0016] The lower water pressure gauge 14 is attached to a position closer to the weight 12 than the upper water pressure gauge 13. Therefore, in a state where the weight 12 is suspended in the suspension liquid by the towing body 11, the lower water pressure gauge 14 is arranged below the upper water pressure gauge 13 in the vertical direction at an interval of the measurement interval d. Thereby, with respect to the water pressure P 上 measured by the upper water pressure gauge 13, the water pressure P 下 measured by the lower water pressure gauge 14 is at a depth that is deeper by the measurement interval d.

[0017] The measurement interval d is preferably set to about 50 cm to 5 m, for example, but there is no particular limitation. However, depending on the measurement accuracy of the upper water pressure gauge 13 and the lower water pressure gauge 14 and the specific gravity of the suspension liquid, the upper and lower limits of the measurement interval d are assumed, and the suitable values also differ. Therefore, it is preferable that at least one of the upper water pressure gauge 13 and the lower water pressure gauge 14 is configured to be detachable with a clip or the like, and the attachment position of at least one of the upper water pressure gauge 13 and the lower water pressure gauge 14 can be changed. Furthermore, by configuring the towing body 11 at the attachment locations of the upper water pressure gauge 13 and the lower water pressure gauge 14 with a graduated scale such as a measuring tape, the measurement interval d can be easily recognized when the attachment position is changed.

[0018] The specific gravity calculation device 20 is an information processing device such as a personal computer, and includes a control unit 30, an input unit 40 such as a keyboard, a storage unit 50 such as a flash memory, and an output unit 60 such as a display or a printer.

[0019] The control unit 30 is an information processing unit such as a microcomputer including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. A control program for the specific gravity calculation device 20 to execute a job is stored in the ROM. The control unit 30 reads out the control program stored in the ROM and expands the control program in the RAM, thereby functioning as a collection unit 31, a specific gravity calculation unit 32, and a depth calculation unit 33.

[0020] When the collection unit 31 receives a measurement instruction from the input unit 40, it collects the measurement values (water pressure P 上 、water pressure P 下 ) of the upper water pressure gauge 13 and the lower water pressure gauge 14 at the same timing and stores them in the storage unit 50 as the measurement result 51. Note that the same timing does not necessarily mean simultaneous. As long as the difference between the measurement depth of the measurement value of the collected upper water pressure gauge 13 and the measurement depth of the measurement value of the collected lower water pressure gauge 14 can be regarded as the measurement interval d. For example, when it is assumed that the upper water pressure gauge 13 and the lower water pressure gauge 14 are stationary and the measurement values are collected, there is no problem even if the collection intervals of the measurement values of the upper water pressure gauge 13 and the lower water pressure gauge 14 are slightly apart. And when it is assumed that the measurement values are collected at a predetermined interval while the upper water pressure gauge 13 and the lower water pressure gauge 14 are lowered or raised, the collection intervals of the measurement values of the upper water pressure gauge 13 and the lower water pressure gauge 14 are set to a sufficiently short time according to the lowering or raising speed.

[0021] When receiving a calculation instruction from the input unit 40, the measurement result 51 (water pressure P 上 、water pressure P 下Based on (1), the specific gravity calculation unit 32 calculates the average specific gravity ρ, and the depth calculation unit 33 calculates the depth from the water surface at the intermediate point between the upper water pressure gauge 13 and the lower water pressure gauge 14 as the intermediate depth H. The average specific gravity ρ is calculated as the specific gravity at the intermediate depth H. Then, the average specific gravity ρ and the intermediate depth H are stored in the storage unit 50 as the calculation result 52 or output from the output unit 60. Note that the specific gravity calculation unit 32 and the depth calculation unit 33 may be configured to automatically calculate the average specific gravity ρ and the intermediate depth H when the measurement result 51 (water pressure P 上 、 water pressure P 下 ) is collected by the collection unit 31.

[0022] The specific gravity calculation unit 32 calculates the average specific gravity ρ by calculating the following formula 1 using the measurement result 51 (water pressure P 上 、 water pressure P 下 ), the known measurement interval d, and the gravitational acceleration g. ρ=(P 下 -P 上 ) / d / g ··· Formula 1

[0023] The depth calculation unit 33 calculates the intermediate depth H at the intermediate point between the upper water pressure gauge 13 and the lower water pressure gauge 14 by calculating the following formula 2 using the measurement result 51 (water pressure P 上 、 water pressure P 下 ), the average specific gravity ρ calculated by the specific gravity calculation unit 32, and the gravitational acceleration g. H=(P 上 +P 下 ) / 2 / ρ / g ··· Formula 2 Note that in Formula 2, the calculated average specific gravity ρ is used, but the depth calculation unit 33 may calculate the intermediate depth H using the measurement result 51 (water pressure P 上 、 water pressure P 下 ), the measurement interval d, and the gravitational acceleration g.

[0024] In this way, the specific gravity measuring device 1 measures the measured values (water pressure P 上 、 water pressure P 下It is possible to measure the average specific gravity ρ at the intermediate depth H without managing the measurement depth. Therefore, by simply suspending the upper piezometer 13 and the lower piezometer 14 in the suspension and measuring at multiple locations while changing the measurement depth, the specific gravity distribution of the suspension can be easily measured. When collecting measurement values at predetermined intervals while lowering or raising the upper piezometer 13 and the lower piezometer 14 and calculating and outputting the average specific gravity ρ and the intermediate depth H from the output unit 60, the specific gravity distribution of the suspension can be measured in real time and continuously.

[0025] As shown in FIG. 3, a rod 12a (for example, a steel rod) made of a material having a specific gravity sufficiently larger than that of the suspension to be measured and having a length longer than the measurement interval d may be used instead of the weight 12, and the upper piezometer 13 and the lower piezometer 14 attached to the rod 12a may be suspended by the towing body 11. In this case, the rod 12a functions as a piezometer arrangement mechanism arranged at a preset measurement interval d in the vertical upper and lower positions.

[0026] (Second Embodiment) Referring to FIG. 4, the specific gravity measuring device 1a of the second embodiment includes an intermediate piezometer 15 disposed between the upper piezometer 13 and the lower piezometer 14 in addition to the configuration of the first embodiment.

[0027] The intermediate piezometer 15 is a device for measuring the water pressure P of the suspension 中 Similar to the upper piezometer 13 and the lower piezometer 14, for example, a pore water pressure gauge for measuring the pressure by the pore water contained in the soil can be used as the intermediate piezometer 15.

[0028] The intermediate piezometer 15 is attached to the towing body 11 between the upper piezometer 13 and the lower piezometer 14 so as to be movable in the vertical direction (up and down direction). The intermediate piezometer 15 is attached to the towing body 11, for example, via a ring mounted on the towing body 11, and is configured to be movable up and down by extending or pulling in a signal cable (or a separate rope) connected to the intermediate piezometer 15 from the ground.

[0029] The weight of the intermediate piezometer 15 may be set to a value sufficiently larger than the specific gravity of the suspension to be measured by attaching a weight or the like. In this case, by supporting the connected signal cable, the intermediate piezometer 15 can be arranged near the upper piezometer 13, and it can be automatically moved downward to the lower piezometer 14 simply by releasing the support of the signal cable.

[0030] Referring to FIG. 5, the control unit 30a of the specific gravity calculation device 20a functions as a collection unit 31a, a specific gravity calculation unit 32a, a depth calculation unit 33a, and a measurement interval estimation unit 34.

[0031] When the collection unit 31a receives a measurement instruction from the input unit 40, it collects the measurement values (water pressure P 上 , water pressure P 下 ) of the upper piezometer 13 and the lower piezometer 14 at the same timing, and also collects the measurement value (water pressure P 中 ) of the intermediate piezometer 15 at the same timing, and stores it in the storage unit 50 as the measurement result 51a. Note that the measurement value (water pressure P 中 ) of the intermediate piezometer 15 may be collected in a fixed state at one location, or a plurality of measurement values (water pressure P 中 ) may be collected while moving in the vertical direction.

[0032] Based on the measurement result 51a (water pressure P 上 , water pressure P 下 , water pressure P 中 ), the measurement interval estimation unit 34 estimates the measurement interval d1 between the upper piezometer 13 and the intermediate piezometer 15 and the measurement interval d2 between the intermediate piezometer 15 and the lower piezometer 14. Note that when a plurality of measurement values (water pressure P 中 ) are collected, the measurement interval estimation unit 34 estimates the measurement interval d1 and the measurement interval d2 corresponding to each of the plurality of measurement values (water pressure P 中 ).

[0033] When receiving a calculation instruction from the input unit 40, the measurement result 51a (water pressure P 上 , water pressure P 下 , water pressure P 中Based on (), the specific gravity calculation unit 32a calculates the average specific gravities ρ, ρ1, and ρ2, and the depth calculation unit 33a calculates the intermediate depth H at the intermediate point between the upper water pressure gauge 13 and the lower water pressure gauge 14, the intermediate depth H1 at the intermediate point between the upper water pressure gauge 13 and the intermediate water pressure gauge 15, and the intermediate depth H2 at the intermediate point between the intermediate water pressure gauge 15 and the lower water pressure gauge 14, respectively. The average specific gravity ρ is calculated as the specific gravity at the intermediate depth H, the average specific gravity ρ1 is calculated as the specific gravity at the intermediate depth H1, and the average specific gravity ρ2 is calculated as the specific gravity at the intermediate depth H2, respectively. Then, the average specific gravity ρ and the intermediate depth H are stored in the storage unit 50 as the calculation result 52a or output from the output unit 60. Note that the specific gravity calculation unit 32a and the depth calculation unit 33a may automatically calculate the average specific gravities ρ, ρ1, ρ2 and the intermediate depths H, H1, H2 when collecting the measurement results 51a (water pressure P 上 、water pressure P 下 、water pressure P 中 ).

[0034] The measurement interval estimation unit 34 calculates the measurement intervals d1 and d2 by calculating the following formulas 31 and 32 using the measurement results 51a (water pressure P 上 、water pressure P 下 、water pressure P 中 ) and the known measurement interval d. d1 = d×(P 中 - P 上 ) / (P 下 - P 上 ) ··· Formula 31 d2 = d - d1 ··· Formula 32

[0035] Note that Formula 31 is based on the premise that the water pressure P 上 rises from the water pressure P 下 towards the depth in proportion. In reality, the greater the depth, the greater the specific gravity of the suspension and the greater the rate of increase in water pressure. Therefore, the measurement interval d1 may be calculated taking into account the change in specific gravity.

[0036] The specific gravity calculation unit 32a uses the measurement results 51a (water pressure P 上 、water pressure P 下 、water pressure P 中Using the known measurement interval d, the estimated measurement intervals d1 and d2, and the gravitational acceleration g, the average specific gravity ρ is calculated in the same manner as in the first embodiment, and the average specific gravities ρ1 and ρ2 are calculated by calculating the following formulas 11 and 12. ρ1=(P 中 -P 上 ) / d1 / g ··· Formula 11 ρ2=(P 下 -P 中 ) / d2 / g ··· Formula 12

[0037] The depth calculation unit 33a uses the measurement results 51a (water pressure P 上 , water pressure P 下 , water pressure P 中 ), the average specific gravities ρ, ρ1, and ρ2 calculated by the specific gravity calculation unit 32a, and the gravitational acceleration g to calculate the intermediate depth H in the same manner as in the first embodiment, and calculates the intermediate depths H1 at the intermediate point between the upper water pressure gauge 13 and the intermediate water pressure gauge 15 and the intermediate depth H2 at the intermediate point between the intermediate water pressure gauge 15 and the lower water pressure gauge 14 by calculating the following formulas 21 and 22. H1=(P 上 +P 中 ) / 2 / ρ1 / g ··· Formula 21 H2=(P 中 +P 下 ) / 2 / ρ2 / g ··· Formula 22

[0038] In this way, the specific gravity measuring device 1a can measure the average specific gravities ρ, ρ1, and ρ2 at the depth between the upper water pressure gauge 13 and the lower water pressure gauge 14 without managing the measurement depths of the measured values (water pressure P 上 , water pressure P 下 , water pressure P 中 ) by the upper water pressure gauge 13, the lower water pressure gauge 14, and the intermediate water pressure gauge 15.

[0039] Then, while moving the intermediate water pressure gauge 15 in the vertical direction, a plurality of water pressures P 中When collecting, it becomes possible to measure the detailed (dense) specific gravity distribution at the depth between the upper piezometer 13 and the lower piezometer 14. Therefore, by densely measuring the specific gravity near the water surface and near the bottom where the specific gravity is likely to change, it is possible to accurately grasp the sedimentation situation of sand and the like near the water surface and the deposition situation of sand and the like near the bottom.

[0040] As described above, the present embodiment is a specific gravity measuring device 1 for measuring the specific gravity of a suspension, which includes an upper piezometer 13 for measuring the water pressure of the suspension, a lower piezometer 14 for measuring the water pressure of the suspension at a depth deeper than the upper piezometer 13, a piezometer arrangement mechanism for arranging the upper piezometer 13 and the lower piezometer 14 at a preset measurement interval d in the vertical upper and lower positions, and a collection unit 31 for collecting the measurement values of the upper piezometer 13 and the lower piezometer 14 at the same timing. With this configuration, using the measurement result 51 (water pressure P 上 , water pressure P 下 ), the known measurement interval d, and the gravitational acceleration g, the average specific gravity ρ and the intermediate depth H at the intermediate point between the upper piezometer 13 and the lower piezometer 14 can be calculated. Therefore, the specific gravity of the suspension can be measured with a simple configuration without measuring the depth of the measurement position.

[0041] Furthermore, in the present embodiment, the piezometer arrangement mechanism is a traction body 11 with a weight 12 attached to one end, and the upper piezometer 13 and the lower piezometer 14 are attached to the traction body 11 at the measurement interval d. With this configuration, the piezometer arrangement mechanism can be realized with a simple configuration.

[0042] Furthermore, in the present embodiment, the piezometer arrangement mechanism is a rod 12a with one end attached to the traction body 11, and the upper piezometer 13 and the lower piezometer 14 are attached to the rod at the measurement interval d. With this configuration, the piezometer arrangement mechanism can be realized with a simple configuration.

[0043] Furthermore, in the present embodiment, the measurement values (measurement result 51: water pressure P 上 , water pressure P 下Using , a specific gravity calculation unit 32 that calculates the average specific gravity ρ at the midpoint between the upper pressure gauge 13 and the lower pressure gauge 14, and the measured values (measurement result 51: water pressure P 上 , water pressure P 下 ) of the upper pressure gauge 13 and the lower pressure gauge 14 respectively, a depth calculation unit 33 that calculates the intermediate depth H at the midpoint between the upper pressure gauge 13 and the lower pressure gauge 14, and an output unit 60 that outputs the average specific gravity ρ calculated by the specific gravity calculation unit 32 and the intermediate depth H calculated by the depth calculation unit 33. With this configuration, the specific gravity distribution of the suspension can be measured in real time and continuously.

[0044] Furthermore, in this embodiment, the pressure gauge arrangement mechanism between the upper pressure gauge 13 and the lower pressure gauge 14 is provided with an intermediate pressure gauge 15 that is movably attached in the vertical direction and measures the water pressure at the depth between the upper pressure gauge 13 and the lower pressure gauge 14. The collection unit 31a collects the measured values (measurement result 51a: water pressure P 上 , water pressure P 下 , water pressure P 中 ) of the upper pressure gauge 13, the lower pressure gauge 14, and the intermediate pressure gauge 15 at the same timing. With this configuration, it becomes possible to measure the detailed specific gravity distribution at the depth between the upper pressure gauge 13 and the lower pressure gauge 14.

[0045] The present invention has been described based on the embodiments. It is understood by those skilled in the art that these embodiments are illustrative, and various modifications are possible for combinations of their respective components, etc., and such modifications are also within the scope of the present invention. For example, three or more pressure gauges with known measurement intervals may be provided, or two or more pressure gauges that can move in the vertical direction may be provided.

Explanation of Reference Numerals

[0046] 1, 1a Specific gravity measurement device 11 Towing body 12 Weight 12a Rod 13 Upper pressure gauge 14 Lower pressure gauge 15 Intermediate pressure gauge 20, 20a Specific Gravity Calculation Device 30, 30a Control Unit 31, 31a Collection Unit 32, 32a Specific Gravity Calculation Section 33, 33a Depth Calculation Section 34 Measurement Interval Estimation Section 40 Input Unit 50 Memory Unit 51, 51a Measurement Results 52, 52a Calculation Results 60 Output Unit

Claims

1. A specific gravity measuring device for measuring the specific gravity of a suspension, comprising: an upper water pressure gauge for measuring the water pressure of the suspension; a lower water pressure gauge for measuring the water pressure of the suspension at a depth deeper than the upper water pressure gauge; a water pressure gauge arrangement mechanism for arranging the upper water pressure gauge and the lower water pressure gauge at a preset measurement interval in the vertical up-and-down position; a collection unit for collecting the measurement values of the upper water pressure gauge and the lower water pressure gauge at the same timing; and the water pressure gauge arrangement mechanism of the upper water pressure gauge and the lower water pressure gauge is provided with an intermediate water pressure gauge that is movably attached in the vertical direction and measures the water pressure at the depth between the upper water pressure gauge and the lower water pressure gauge; the collection unit is characterized in that it collects the measurement values of the upper water pressure gauge, the lower water pressure gauge, and the intermediate water pressure gauge at the same timing. A specific gravity measuring device.

2. The specific gravity measuring device according to claim 1, wherein the water pressure gauge arrangement mechanism is a towing body with a weight attached to one end, and is attached to the towing body at the measurement interval.

3. The specific gravity measuring device according to claim 1, wherein the water pressure gauge arrangement mechanism is a rod with one end attached to a towing body, and is attached to the rod at the measurement interval.

4. a specific gravity calculation unit for calculating the average specific gravity at the intermediate point between the upper water pressure gauge and the lower water pressure gauge using the measurement values of the upper water pressure gauge and the lower water pressure gauge respectively; a depth calculation unit for calculating the depth from the water surface at the intermediate point between the upper water pressure gauge and the lower water pressure gauge as the intermediate depth using the measurement values of the upper water pressure gauge and the lower water pressure gauge respectively; The specific gravity measuring device according to any one of claims 1 to 3, further comprising an output unit for outputting the average specific gravity calculated by the specific gravity calculation unit and the intermediate depth calculated by the depth calculation unit.

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