Proceedings of the First International Conference on Press-in Engineering 2018, Kochi

Measuring System of Improved Diameter in High Pressure Injection Mixing
MethodMasatoshi UNO
Civil Engineering Technology Division, Shimizu Corporation, Tokyo, Japan
Email: uno@shimz.co.jp

Shiho SAIMEN
Kanto Branch, Shimizu Corporation, Saitama, Japan
Email: saimen@shimz.co.jp

Juichi ISE
Civil Engineering Technology Division, Shimizu Corporation, Tokyo, Japan
Email: j.ise@shimz.co.jp

ABSTRACTThe high-pressure injection agitation method is a construction method to improve the soil by creating an improved
columnar body by injecting with a jet of grout. Confirmation of such improved diameter is usually performed by checkboring after the ground improvement, which takes time and becomes one of the reasons of the delay to deal with poor
construction and troubles. We have developed a high pressure injection measuring system that can physically confirm
the improved diameter by extruding a feeler into the improved body during construction. By use of this system, it ispossible to deal with the insufficient diameter of completed improved body, which is to immediately recover its quality
during the construction.
Key words: measuring system, improved diameter, high-pressure injection, measuring rod tube

1. Introduction
As for the improved diameter of the high-pressure

Water

injection stirring method, it is common to check boring

Enlarged view

after construction and confirm the molded shape. However,it takes time with this method to confirm the improved
diameter, and the response is also delayed when theshortage of improved diameter is detected.
Therefore, we have developed a system that canWater

Improved
body

immediately measure the improved diameter after
completion of construction to confirm the molded

Pistondiameter immediately after construction, which leads toassure better quality and shorten the work period.

FeelerFeelerFig. 1- 621 -The outline of the measurement systemoutlineProceedings of the First International Conference on Press-in Engineering 2018, Kochi

Fig. 1 shows the outline of the measuring system andmock improved body. A sheathing board was installed into
this body at a distance of 1.75 m from a measuring rod

Fig. 2 shows the photo of the measuring rod tube.
In this paper, we report the results of mock-up field

tube, as an alternative to the improved end, assumed to beexperiments and verification test, which were conducted

the ground. Then, we confirmed a change in waterto verify the validity of this system.

injecting pressure at the position of the sheathing board
and the measuring error in the distance measuring sensor.

2. Outline of measuring system method
The overall view of the measuring system is shownin Fig. 3. In this system, a measuring rod tube is inserted
into an unconsolidated improved body immediately after
the injection, a feeler is pushed out by water pressure fromthe tip part of the feeler-device, and the distance from therod to the ground is measured by the feeler contacting tothe ground. The improved diameter is confirmed bymultidirectional measurement with changing the directionof the feeler. The measurement data is stored on the cloudserver via Internet. Fig. 4 shows the water pressure
measuring system used for the measurement. This systeminjects a water from the water pump into the measuring
rod tube, extrudes the feeler into the unconsolidated
improved body, and measures the water supply pressure at
the same time. Soft ground improved by injection is softer
than the original ground until solidification progresses,

Fig. 2The measuring rod tube

allowing feeler to penetrate with less resistance. However,when going out of the area of injection and entering thebase ground, resistance increases. When the feeler contact

Internetい内Distancemeasuring Sensor 管
変位量センサーパwith a harder material than the unconsolidated improved

Data③データ計測・収集装置
measurement（エンパソル）

body (which is the ground), the water injecting pressure

４ｍ程度

イプ

Boring②ボーリング
machine

押出しライン
水Waterマシン

increases so that it detects the end of the improved body.

④フィラー
押し出し用送水ポンプ
水圧センサー

3. Mock-up Field Experiment

Water pump
改良体部分

Improvement
bodyexperiment. A mock improved body was prepared for thisexperiment. There were two purposes in this test; firstly toピストン

Rod tube

3.1. Outline of experimentFig. 5 shows the schematic view of the mock-up

計測管（ジョイントパイプ）（内管パイプ）

外管
パイプ

Fig. 3Feelerフィラー①フィラー装置

フィラー
Feelerフィラー装置構造
Feeler device

Feeler-device

The overall view of the measurement system

check whether this system is capable to measure theWire type linear encoder

accurate distance by using a sheathing board which is setat a known distance; secondly to know the limitation ofUSB, SD card
Internet

the applicable (vane shear) strength of the improved bodyPressure transformer

or maximum elapsed time for this system, by measuring
the vane shear strength at each elapsed time.
3.2. Method
Three different samples of viscous soil, sandy soil,
and sandy soil mixed with gravel were used to prepare theTablet PC

Fig. 4

The water injecting pressure measuring systemsystem- 622 -

Proceedings of the First International Conference on Press-in Engineering 2018, Kochi

In addition, we investigated the elapsed time and theRod

Boardvane shear strength after mixing the mock body, and theImprovement bodyaccuracy of each value in the measuring device at that time,Feelerand obtained the limitation to measure each value.
Regarding the distance from the rod to the board, it
was set at 1.75 m as a radius of improved diameterassumed to be 3.5 m.

Fig. 53.3. Materials and mixture
The applied materials and mixtures are shown in

The schematic view of the mock-up experiment

Table 1.

was mixed with a solidification slurry (W / C = 100%) ata volume ratio of 1:1 to prepare a mock improved body.

soil. A large response was observed in the water injecting

Kibushiclay
Silicapowder
Kashima
Silica Sand
3B
Kashimagravel
2-8 mmWaterpressure at 1.75 m from the rod, where the board was(water contentratio)

installed in every sample body. Therefore, it waswet density

Fig. 6 shows the distribution of particle sizes in the sample
soil.
3.4. Results
Fig. 7 shows the experimental situation. Fig. 8 shows
the measured results of water pressure at an elapsed timeof 120 min after mixing the mock body by each sample

demonstrated that the diameter of the improved body canbe confirmed by this system.
Fig. 9 shows the measured results of water injecting

The mixtures in each material

TypeSoil

Table 1. Each sample soil from A to C shown in the tablesoil:Aclay

soil:Bsand

75soil:C
Mixed sandwith gravel
5322-

32--

130%
added

20%
added

18% added

1.70

1.79

1.83(g/cm3)**The wet density indicates the density after mixing sample
soil and grout slurry (W/C = 100%) at 1: 1 by volume.

pressure at the limitation of the measuring devices. The
rod which was the installation position of the board, but
the pressure still kept rising thereafter. In this state, it was
confirmed that the feeler folded over and damaged in therod tube. This similar tendency was found in all the sample
soils, and it was assumed that the feeler could not move
within the improved body when it contacted the sheathingboard and also the mock body exceeded a certain shear
strength. Therefore, in this experiment, the vane shear

Exceedance probability of volume

injecting pressure reacted at the point of 1.75 m from theSoil:A (Clay)
Soil:B (Sand)
Soil:C (Sand with gravel)

strength at this time was judged as the measuring
limitation of the measuring devices.

Particle size

Fig. 10 shows the growth of the vane shear strengthof mock improve body using Clay (soil: A), Sand (soil: B),
Mixed sand with gravel (soil: C), and the measured
limitation of the measuring device is also shown.

- 623 -Fig. 6

The distribution of particle sizes
in the sample soil

Proceedings of the First International Conference on Press-in Engineering 2018, Kochi

Vane shear strength

Soil:A
Soil:A(limit)
Soil:B
Soil:B(limit)
Soil:C
Soil:C(limit)

Elapsed time

Fig. 70.0

The experimental situation

Fig. 10

Soil:A
Soil:C①粘性土②砂質土
Soil:B ③礫混じり砂質土
送水圧
送水圧
送水圧
WP MPaWP MPaWP MPa0.00
2.00 0.00
2.00 0.00
2.00

The growth of the vane shear strength of mock
improve body in each type of soil

The measured limitations were 0.49 kN/m2 for theDistance from the rod

body with clay soil, 1.48 kN/m2 for that with sand soil, andロッドからの 1.0距離（m）

0.81 kN/m2 for that with mixed sand with gravel., The
1.75m

measurement limit values of the simulated advanced bodyvaried depending on the type of soil sample, however it
was found that rough measurement was possible in thecondition that the measurement limit value was less than
0.4 kN/m2.
The measured limitation of the elapsed time wasmerely a reference value, considering that the airtemperature at the time of this experiment was around 10

2.0Fig. 8

Water injecting pressure at 120min.

Soil:A
Soil:C
Soil:B①粘性土②砂質土③礫混じり砂質土
送水圧
送水圧
送水圧
WP MPaWP MPaWP MPa2.000.00
2.00 0.00
2.00 0.00

Distance from the rod

0.0

degrees and might not be equal to the underground

ロッド
からの 1.0
距離（m）

temperature in actual construction. Therefore, it is a futuretask to grasp the limitation of the elapsed time.
3.5. Summary
By using this developed measuring system, it was
discovered to be possible to measure the improved
diameter after completion of construction when the vane

1.75m

shear strength of the unconsolidated improved body wasless than 0.4 kN/m2, which seemed to be the measuring
limitation, varying somewhat depending on the type of thesoil to be improved.

2.0Fig. 9

Water injecting pressure as the limitation- 624 -Proceedings of the First International Conference on Press-in Engineering 2018, Kochi

Table 3 and Fig. 12 show the measured results.

4. On-site test
4.1. Objectives
The on-site test was carried out at the site of

According to the Table 3, there are differences inconstruction of the Hanko Shorenjigawa-nishi Open Cut

downstream side. The diameter of the improved bodyTunnel. High-pressure injection stirring construction

from the upper side to the downstream side is 2.28 m,

method was planned at the lower part of the bridge ofwhile that from the left side to the right side is 2.47 m. It

Route 43. The Specification with an improved diameter of

was confirmed by this system that the former diameter was

2.3 m was designed at that site. We confirmed theslightly lower than the value of the planned 2.3 m but

improved diameter by this measuring system to verify its

could be concluded that both were almost created as

effectiveness and validity during the trial construction.

planned.

measured absolute values on the upstream side and theThe difference in measured absolute values between
4.2. Outline of on-site test

the upstream side and the downstream side depends on the(1) Construction:

fact that the position of the measurement rod installation

Shorenjigawa-nishi Open Cut Tunnel site

biased somewhat toward the upstream side. In this system,(2) On-site test position:

however, even in such situation, it was also confirmed that

Within the area of the 24 BL test site (Fig. 11)

the improved diameter could be grasped by inverting the(3) On-site test period:

measuring direction

December 8 to 10, 2010
Improvement drilling: June 9, 2011

Table 3.

(4) Improved Specifications:
Table 2 shows the improved specifications.
UpDown
Left
Right

Downstream
Left bank
Test site
15m×10m

Measurement
（m）
1st
2nd
0.915 0.905
1.395 1.350
1.130 1.120
1.345 1.325

Measured results
Ave.
（m）

Diameter
（m）

0.91
1.37
1.13
1.34

Plan（m）

2.28
2.3
2.47

Left bank
左岸側

Right bankMeasuredshape
計測による予想杭形状

1.13m

Upstream
Upstream
上流側

Fig. 11 24 BL test site for onsite test

Downstream
下流側

1.37m

The improved specifications

Design improvement
diameter
Design improvement
strength
Viscosity
Improved depth range

φ2.3m

1.34m

Table 2.

0.91m

quf＝770kN/m2
Cu＝20～30kN/m2 less than
（OP-9.0m～-10.5m）
GL-5.6m～-7.1m（1.5m）

計画杭形状
Plan shape
PlannedRightbank
右岸側
Rightbank

4.3. Results
After the construction of the trial improvement body,measurements by this system were made at the ground
improvement place.

- 625 -Fig. 12The monitoring result

Proceedings of the First International Conference on Press-in Engineering 2018, Kochi

4.4. Confirmation by drilling improved body
The drilling was carried out after curing of the

5. Conclusion
From the results of mock-up field experiments andrefinement. Fig. 13 shows the improved body after

on-site test, it was found that the improved diameter of thedigging. The measured result was 2.4 m in the diameter ofhigh pressure injection machine could be measured withthe refiner and 2.38 m in the upstream and downstream

high accuracy immediately after construction by thedirection. The average diameter of the measured results

measuring system of the improved diameter. However, thewas 2.39 m.

measurement becomes impossible when the improved
下流

body exceeds a certain hardness due to the measuring

Downstream

limitation in the actual construction. It is necessary to takemeasures such as mixing retarders in the slurry in order toadjust the time to the measuring limitation by also taking
the measuring time into consideration.
In the future, the remaining task to accumulate

Left bankachievements by actual construction and to modify thisRight banksystem is hoped to be accomplished.

Diameter
φ2.39m

6. Acknowledgements
Our thanks to Raito Industry Co., Ltd., which

Upstreamdeveloped this method jointly, and people in the field,Fig. 13
Table 4.

cooperated in development tests etc. We express our best

Improved diameter verified by digging
improved body

gratitude here.

Comparison of measured results by digging

References
Seimen, S., Ise, J., Nozu, T., Abe, M. 2012. Development

Diameter evaluation result

plan
Measurement
systemActualmeasurement

Up-Down

Right-Left

Averageof an improved diameter measurement system indirection.

directiondiameterhigh pressure injection stirring method. Summary of2.3m or

the 67th Annual Academic Lecture Meeting of theJapan Society of Civil Engineers Conference, VI-2.3mor

2.3mor

more

more

more

2.28m

2.47m

2.38m

2.38m

2.40m

2.39m

486. (in Japanese)
Shimizu Corporation, Raito Industry Co., Ltd. 2012.
Improved

diametermeasurementsystem.

Construction Planning, No. 752, pp. 86. (inJapanese)

4.5. Summary
Table 4 shows the comparison between the result ofConstruction Industry Research Committee.

the measuring system of the improved diameter and thatmeasured after actually being dug out.
The difference between the result by measuringsystem and by the excavation was 10 cm on the upstreamside and 7 cm on the right side left side. The difference
were range of error. From this result, it was discovered thatmeasurement by this system could be performed with highaccuracy.

- 626 -

Revised Groundwater Handbook, pp. 120.

1998.