PROOF EXPERIMENT USING ARTIFICIAL EARTHQUAKE CONCERNING EFFECT OF PERMEABLE GROUTING METHOD AS MEASURES AGAINST LIQUEFACTION

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1 13 th World Conference on Earthquake Engineering Vancouver, B.C., Canada August 1-6, 24 Paper No. 38 PROOF EXPERIMENT USING ARTIFICIAL EARTHQUAKE CONCERNING EFFECT OF PERMEABLE GROUTING METHOD AS MEASURES AGAINST LIQUEFACTION Kensuke KAWAMURA 1, Hiroyuki YAMAZAKI 2, Takahiro SUGANO 3, Kentaro HAYASHI 4 SUMMARY In this study, we conducted a field experiment to confirm the liquefaction resistance of Permeable Grouting Method. From the result of the measured data of the acceleration in the ground, the steel sheet-pile displacement, the steel sheet-pile back earth pressure, the excess pore water pressure, and the ground subsidence, it is found that improved soil by this method has remarkable resistance against liquefaction. From the observation of the improved region after the experiment, any phenomenon such as evidence of sand boil was not found at all. Thus, through this real large scale field experiment, the capability of the Permeable Grouting Method for prevention of liquefaction occurrence and for reducing the earth pressure were proved. INTRODUCTION On November 13, 21, Port and Airport Research Institute and fourteen organizations in Japan and the U. S. have conducted joint research on "Full-scale Experiment Concerning Improvement of Earthquakeproof Functions in Ports and Waterfront Cities" [1] on the reclaimed ground at Tokachi Port, Hokkaido. A full-scale model of the steel sheet pile quay with 5.5m in depth was constructed. The liquefaction and the vibration of the ground were reproduced by the blast with the emulsion dynamite where three dimensions were arranged behind the quay. We confirmed the effect of countermeasure against liquefaction by the Permeable Grouting Method as one of the joint researches. In this paper, at first, the outline and characteristic of the Permeable Grouting Method is shown. Next, the results of the experiments are shown. This paper describes the comparison of the acceleration and the sheet pile displacement, etc. in the area improved by the Permeable Grouting Method and in the original ground respectively. Moreover, it is found that the Permeable Grouting Method is effective to the countermeasure against liquefaction and the earth pressure decrease by conducting the full-scale experiment. 1 Chief Engineer, Penta-Ocean Construction Co.,Ltd., Nishi-Nasuno Town, Japan. Kensuke.Kawamura@mail.penta-ocean.co.jp 2 Head of soil dynamics division, Port and Airport Research Institute, Yokosuka City, Japan. 3 Head of structural dynamics division, Port and Airport Research Institute, Yokosuka City, Japan. 4 Professional Engineer, Penta-Ocean Construction Co.,Ltd., Nishi-Nasuno Town, Japan.

PERMEABLE GROUTING METHOD Outline of the method The Permeable Grouting Method [2-5] was developed aiming to prevent liquefaction beneath or near the existing structure.

2 PERMEABLE GROUTING METHOD Outline of the method The Permeable Grouting Method [2-5] was developed aiming to prevent liquefaction beneath or near the existing structure. As shown in Figure-1, in this method, the ground is improved by boring the ground, injecting the chemical grout of the solution type and solidifying that grout. Though it is necessary to install the boring hole in the ground, the preventing liquefaction is possible directly against the ground right under the existing structure. By injecting the chemical grout, it became possible to produce improved soil in an area of 4m in diameter under certain ground conditions. Therefore, the injected chemical grout has good permeability and permanent. Photo-1 shows the shape of improved soil with a diameter of 2.5m, which was confirmed by excavation at the test site in Matsuzaka City in Japan after the injection of chemical grout. Chemical Grout Injection Existing Structure Chemical Grout Injection Figure-1 Image of Permeable Grouting Method Photo-1 Shape of Improved Soil Characteristic of the method Comparison with the conventional chemical grouting method As shown in Table-1, the difference from the conventional chemical grouting method is as follows. 1) The chemical grout must infiltrate a wide-ranging 1Expand the 2Expand the 3Chemical ground (about 4m in maximum diameter) from Textile Packer Double Packer Grouting one injection exit. 2) Strength of the improved soil must be low strength (About q u =1kN/m 2 ). 3) The chemical grout must have permanent. So, to enlarge the range of infiltration especially, the gel time of the chemical grout will be set in several hours. And, as shown in Figure-2, the length of the injection exit is about 5cm longer than usual length of about 1cm. Textile Packer Injection Exit Thus, in the injection exit having become long, more 1cm Strainer chemical grouts' being injected into the ground by low Figure-2 Strainer-Type Grouting Plant pressure became possible. Comparison with other solidification methods The Permeable Grouting Method has the following difference with the solidification methods with cement etc. like the Premixing Method [6]. As shown in Figure-3, when the sandy soil is solidified by the Premixing Method, only the contact point of the particle of the sand is solidified with cement and the 47.5cm

3 Table-1 Comparison with Conventional Chemical Grouting Method conventional chemical grouting method Permeable Grouting Method Grout Cement Type Water Glass Type Colloidal Silica Scale of Grouting Limited Area Wide Area Penetration Area about Diameter of 1cm Max Diameter of 4cm Unconfined Compressive about 2~1kN/m 2 about 5~1kN/m 2 Durability Temporary Long Term Strength ground is not liquidized, but the pore water remains between the particles of the sand. In the Permeable Grouting Method, because the pore water in the particles of the sand is substituted by the chemical grout and the grout gels and the pore of the soil is completely full of the gel, there is a feature that not only uniting particles of sand but also the pore water is driven out. Therefore, in the improved ground by the Permeable Grouting Method, even if a big earthquake occurs from the design earthquake and the liquefaction resistance is insufficient, it is thought that the sand boil and the second liquefaction of the ground in the surrounding according to the spread of the excessive pore water pressure does not happen because of no pore water in the ground. Characteristic of the chemical grout The chemical grout used by this method is a solvent-type permanent chemical with Na + ion removed, which causes degradation, from water glass using an electro-osmosis membrane. Figure-4 shows the comparison of durability between the conventional chemical grout and the Special Silica used by this method. This Figure is a graph showing the leaching ratio of SiO 2 from a solid substance that causes strong degradation of improved soil. Furthermore the data other than that of Special Silica in the graph was quoted from Yonekura (1992) [7]. As is apparent from the Figure, the conventional chemical has over 1% leaching ratio, whereas Special Silica has only a few percent. We can tell from this that the improved soil by Special Silica has long durability. Leaching Ratio of SiO2 (%) Pore=Water Soil Particle Pore=Gel Improved with Solvent-Type Solidified with Cement Cement Pore=Water Figure-3 Improved Image by Solidification Methods Elapsed Time (day) Special Silica 1 Special Silica 2 Inorganic Water Glass Grout Inorganic Water Glass Grout Organic Water Glass Grout Organic Water Glass Grout Figure-4 Leaching Ratio of SiO 2 from Solid Substance

4 Characteristic of the improved soil Figure-5 shows the liquefaction resistance of the untreated soil of the Niigata sand and the improved soil to q u =1kN/m 2 of the Niigata sand. From this Figure, the liquefaction resistance of the improved soil becomes twice or more the untreated soil. Figure-6 shows the time scale history of the cyclic deviator stress ratio, the axial strain and the excess pore water pressure ratio and the effective stress pass of the untreated soil of the Rokko masado under the cyclic triaxial test. Similarly, Figure-7 shows a result of the improved soil of q u =6kN/m 2 of the Rokko masado. In the untreated soil, when the excess pore water pressure ratio approaches 1., the axial strain is rapidly generated, the effective stress becomes zero and the liquefaction is generated. On the other hand, in the improved Liquefaction resistance R L2 soil, when the excess pore water pressure ratio approaches 1., the axial strain is not rapidly generated, the effective stress does not become zero and the liquefaction is not generated. Therefore, for the improved soil, even if the loads bigger than the liquefaction resistance acts, the liquefaction that usual sand becomes like the liquid is not generated and it is thought that the improved soil has stickiness like clay Improved Soil Distortion Amplitude=5%, Niigata Sand, Dr=5%.1 Untreated Soil Number of Cycles to Cause Liquefaction N c Figure-5 Liquefaction Resistance of Improved Soil and Untreated Soil Pore Water Pressure Ratio Cyclic Dviator Stresss Ratio Axial Strain εa(%) Deviator Stress q(kn/m 2 ) Mean Effective Stress p'(kn/m 2 ) Figure-6 Results of Cyclic Triaxial Test of Untreated Soil

5 Pore Water Pressure Ratio Cyclic Dviator Stresss Ratio Deviator Stress q(kn/m 2 ) Axial Strain εa(%) Mean Effective Stress p'(kn/m 2 ) Figure-7 Results of Cyclic Triaxial Test of Improved Soil Figure-8 shows the relationship between the unconfined compressive strength (q u ) and the liquefaction resistance (R ck ) of the improved soil. The liquefaction resistance (R ck ) is a shear stress ratio when the cyclic loads become 2 times and the distortion amplitude reaches 5% under the cyclic triaxial test. From this Figure, it is understood that R ck strengthens when q u strengthens, and there is a significant relation up to both. The liquefaction resistance is R ck =.5 in q u =8-1kN/m 2, and this is corresponds to the liquefaction resistance for usual dense sand, and considerably large liquefaction resistance. Liquefaction Resistance Rck Unconfined Compressive Strength q u (kn/m 2 ) Figure-8 Relationship between R ck and q u FULL-SCALE PROOF EXPERIMENTS Outline of experiments Experiment yards Figure-9 shows the whole arrangement of the experiment yard. Earthquake-proof design steel sheet pile quay (design seismic coefficient, k h =.15) and traditional design steel sheet pile quay (k h =) were constructed in the Tokachi Port landfill. The structural type of the quays was raking pile type, they were 5.5m in front depth, and extended 25m. The range of 75m behind the quay walls was maintained as the experiment yard. Each participated in the joint research organization set up the experiment equipment

6 PARI UCB & CDM Association JGS Quay Walls Applied to Seismic Design Criteia Quay Walls Subjected to Lateral Spreading PARI JDREA JASPP Design Depth -5. Permeable Grouting Method Improved Area PARI JDREA JASPP 1:2 1:2 D1 Design Depth -5. D2 D3 C A41 A31 A3 A4-1. AD2 AD1 WASEDA Univ. +3. A42 A29 A39 A32 CHUO Univ. A54 A49 A48 AD3 PP2 A1 A2 AD4PP1 A43 WASEDA Univ. A28 B1 B3 B4 B5 B6 B7 A38 A33 B2 A53 A5 A47 AD5 PP6 A5 CHUO Uiv. AD5 PP5 A44 A27 C1 C2 C3 C4 A37 A34 C5 AD8 A52 A51 A46 AD7 PP3 AD9 PP4 A45 A26 D1 D2 D3 D4 A A35 E1 E2 F1 E3 E B48 B B46 B45 B1 B41 E5 B42 F2 B43 B44 B4 B39 S2 B38 B37 B C1 UCSD L=11.5m +3. UCSD L=11.5m S7 B33 B32 WASEDA Univ. L=1,5 E6 S11 B34 S6 B31 UCSD S4 S1L=11.5m B3 S3 S5B35 S8 B3 B29 6. C2 WASEDA Univ. S9 B25 B26 S1 B27 B28 C3 UCSD L=25.6m B24 A CHUO Univ. B23 B18 B4 B22 B21 C4 UCSD L=25.6m A21 A C5 C24 A23 A24 B17 B19 B2 C23 A2 A19 A A17 A16 B16 B13 A4 A11 A12 A13 A14 A15 B9 B12 B5 A1 A9 A8 A7 A6 B8 6. A1 A2 A3 A4 A5 B1 B15 B1 B7 B2 UCSD L=22.m S12 WASEDA Univ. NILIM B14 B11 B6 B3 C6 9@6=54. C22 C7 C21 C8 6. B4 C2 1:1 C19 C18 C17 C16 C15 C1 C9 5.2 WASEDA Univ. C14 C13 C12 C @6= @6= Figure-9 Experiment yards within the range. The emulsion dynamite was used for generating an artificial earthquake. 12 holes were made in the experiment yard to mount dynamites. Furthermore, another 25 holes were made surroundings the area. Two dynamites were set up for each 127 holes in total. In the experiment yard, blasting started from a place that was the furthest from the quay at the earthquake-proof design quay and the traditional design quay, simultaneously. After blasting reached quays in the experiment area, the blast outside the area, which had been set up in a basic layer, was done. The blast was done at.7 seconds intervals and started about 7 seconds after the experiment begun. It reached the place between the raking piles about 39 seconds later and the blast in the area ended about 45 seconds later. Afterwards, the blast outside the area was done. The entire vibration time was about one minute. Construction of Permeable Grouting Method Using a part of the earthquake-proof design steel sheet pile quay coducted the experiment of the Permeable Grouting Method. Figure-1 shows the range improved by the Permeable Grouting Method and the arrangement of measuring instruments and apparatus. The difference of the behavior of the tie-rod and the tie-wire was observed in the earthquake-proof design quay with 25m. Therefore, since there may be an influence on other experiments if the foundation improvement work by the Permeable Grouting

7 Method is widely done; Plane arrangement of the improvement was 4.m 2m. For the behavior comparison between the improvement region and the original ground area, the measurements of the acceleration meter, pore water pressure meter, earth load gauge, and the load cell (tensile meter) set up at the position in the figure, and the displacement gauge and the subsidence board was used. Plan View C D Aseismatic Design Steel Sheet Pile Quay Non-aseismatic Design Steel Sheet Pile Quay Tied Wire 2 Section C-C,D-D C D Improvement Unimprovement Region Region Improvement Region by PGM Pore Water Pressure Meter Acceleration Meter Earth Pressure Gauge Road Cell Settlement Measure Plate Displacement Measuring Point (by GPS) Dynamite Tied Wire(TR52φ32) Dynamite (3kg) Steel Sheet Pile(Type Ⅲw) Raking Piles(H-35) Dynamite (4kg) Experiment results and consideration -9.2 Figure-1 Improved Area by Permeable Grouting Method Situation after experiments Photo-2 shows the situation after the experiments. A rectangular above the line of the center part in the photograph is a range of the improvement by the Permeable Grouting Method. Though the outflow of the sand boil or underground water to the ground level is seen in the original ground around the improved range; As for the range where the ground has been improved by the Permeable Grouting Method, the generation of the liquefaction such as sand boils was not observed.

Dynamic characteristics Figures 11 to 14 show the comparison of the dynamic characteristics between the improvement region and the Improved Area original ground in the earthquake-proof design quay.

8 Dynamic characteristics Figures 11 to 14 show the comparison of the dynamic characteristics between the improvement region and the Improved Area original ground in the earthquake-proof design quay. The summary of the experiment results in this text pays attention to only the blast in the area where the influence exists directly within the range of the improvement. In the figures of the earth pressure, the excess pore water pressure, and the tension, the components with high frequency of 2Hz or more are removed in order to smooth data. From the measurement of the horizontal displacement at the top part of the steel sheet pile quay, it turns out that it is slightly smaller in the Photo-2 Situation after Experiment improved ground in comparison with that in the original ground (see Figure-11). Moreover, a remarkable difference is not seen about the tie-wire tension in dynamic characteristics of the improvement region and the original ground area (see Figure-12). It is likely that the pile head concrete, placed in the entire earthquake-proof design sheet pile quay, combined the improvement region with the original ground area. As for the tie-wire tension, the measurement value of the tension increment was 6kN/wire. Since the design by which the lateral seismic coefficient is assumed to be k h =.15 was 77kN/wire, it is judged that there was no big difference. The improved effect was able to be confirmed about the earth pressure (see Figure-13). Some decreases are observed in the improvement region while the earth pressure has increased gradually in the original ground area. This is because the improvement body is about to become independent for the sheet pile transformation. The excess pore water pressure (shown in Figure-14) is increased to the effective earth covering pressure level (about 3kN/m 2 ) in the original ground area. Therefore, the generation of the liquefaction can be confirmed from the measurement result. On the other hand, it does not increase up to the effective earth covering pressure in the improvement region. As a result, the liquefaction is not generated in the improvement region. Horizontal Displacement X(mm) Improved Ground Horizontal Displacement Horizontal Accelration Original Ground Horizontal Accelration a(g) Tension of Tied-Wire T(kN) Improved Ground Tension of Tied-Wire Horizontal Accelration Original Ground Figure-11 Results of Horizontal Displacement Figure-12 Results of Tension of Tied-Wire Horizontal Accelration a(g)

9 Earth Pressure p(kn/m 2 ) Improved Ground Earth Pressure Horizontal Accelration Original Ground Horizontal Accelration a(g) Pore Water Pressure u(kn/m 2 ) Improved Ground Pore Water Pressure Horizontal Accelration Original Ground Figure-13 Results of Earth Pressure Figure-14 Results of Pore Water Pressure Horizontal Accelration a(g) Settlement measurement results Photo-3 shows the situation of the settlement board of before and right after the experiments. Figure-15 shows the settlement measurement results. The settlement right after experiment was mm in the improvement region, and it was 8mm in the original ground area. The following day settlement was 21mm in the improvement region, 196mm in the original ground area, and the difference of about 18mm was generated from the experiment on the settlement board. The settlement at the improvement region is far smaller compared with the original ground though the settlement tendency cannot be specified since the measurement frequency was a little. Settlement (mm) Elapsed Time from Experiment Beginning (hour) Original Ground Improved Ground Figure-15 Results of Settlement 196 Unconfined compressive strength of improved soil The unconfined compression test was done by using an obtained specimen from the locale by the Rotary Triple Tube Sampler before the experiment (the 28th in the age) of the vibration and after the experiment (the 56th in the age)(see Table-2). In any case, site strength of the improved soil is about 1/2 of the indoor strength. The construction of the Permeable Grouting Method has been proven to be appropriate. There was no decrease in the improved strength after the experiment. The unconfined compression test results show that there was no damage in the improvement body by the vibration experiment.

Settlement due to Liquefaction is 8mm 2mm 2mm Before After Before After Original Ground Improved Ground Photo-3 Behavior of Settlement Plate Table-2 Unconfined Compressive Strength of Improved Soil

10 Settlement due to Liquefaction is 8mm 2mm 2mm Before After Before After Original Ground Improved Ground Photo-3 Behavior of Settlement Plate Table-2 Unconfined Compressive Strength of Improved Soil Unconfined Compressive Strength q u (kn/m 2 ) Site Laboratory Before Experiment After Experiment (Age 28 Days) (Age 28 Days) (Age 56 Days) No.1 No.2 No.1 No Specimen No. Average CONCLUSION We can get the effective experiment results about the Permeable Grouting Method as follows. 1. To Prevent the liquefaction 2. To Reduce the Earth Pressure REFERENCES 1. Kohama, E. Full-scale experiment on aseismatic inclination of harbors and seaside part city function, The Japanese Geotechnical Society, Tsuchi-to-Kiso, Vol.5, No.2, 22. : Yamazaki, H. Study on applicability of Permeable Grouting Method to countermeasure against liquefaction, Report of Port and Airport Research Institute, Vol.41, No.2, 22. : Hayashi, K. A field test on a new chemical grouting method to improve the liquefaction resistance of sandy layers beneath the existing structure, Proceeding of IS-YOKOHAMA, Vol.1, 2. : Hayashi, K. Fundamental tests on stabilized sand using acid silica sol, Proceeding of IS- TOKYO 96, : Hayashi, K. A method to countermeasure the liquefaction beneath the existing structures, Japan Waterfront Journal WAVE NIPPON, Vol.16, 22. : Coastal Development Institute of Technology, The Premixing Method principal, design and construction, AA Balkema, Yonekura, R. Long time durability of chemical grouts, The Japanese Society of Soil Mechanics and Foundation Engineering, Tsuchi-to-Kiso, Vol.4, No.12, :

Controlled Curved Drilling Technique in the Permeation Grouting Method for Improvement Works of an Airport in Operation

Procedia Engineering Volume 143, 2016, Pages 539 547 Advances in Transportation Geotechnics 3. The 3rd International Conference on Transportation Geotechnics (ICTG 2016) Controlled Curved Drilling Technique