In this study, geotechnical properties of bamboo chips-soil mixture and its applicability as pedestrian pavement are investigated by a series of laboratory and in-situ tests. The following conclusions are obtained from this study: (1) Even if the bearing capacity of the bamboo chips-soil mixture decreases by the increase of mixture rate of bamboo chips, the value of CBR can be ensured 10% or more. Therefore, the bamboo chips-soil mixture can be used as a pedestrian pavement material. (2) Unconfined compressive strength of the bamboo chips-soil mixture is increased gradually according to the increase of mixture rate of bamboo chips. Also, by mixing many bamboo chips into the sandy soil and compacting the mixture densely, the stiffness of the bamboo chips-soil mixture becomes higher. (3) Even if the mixture was compacted densely, the bamboo chips-soil mixture is able to be ensured high permeability comparable to coarse sand or gravel. (4) Amount of the impact absorption of pedestrian pavement using the bamboo chips-soil mixture is affected significantly due to the change of climate. Increasing walkers, the surface of the pedestrian pavement is compacted and then becomes hard gradually. By using many bamboo chips, the impact absorption of the pedestrian pavement approaches that of the artificial grass pavement.
While cutting asphalt pavement surfaces, cooling water is continuously given to the cutting machine blades to prevent the heat increase and to control the scatter of cutting dusts. As the results, asphalt pavement cutting waste water is generated. The amount of waste water generated at one construction site is by no means a lot, however, the water quality is not environmentally friendly. In view of above, the physical and chemical properties of cutting waste water were first investigated. Then the possibility of effective use of the cutting waste water was investigated using flocculants and granulation technique. The results show that the waste water quality can be improved by the effects of flocculants. Mud sediments after flocculated in the waste water can be granulated and the granules may be used as recycle crusher-runs aggregates.
The “high-standard micro-piles method” which is also possible at a narrow space, low altitude head condition and low cost has been developed as a new construction method for reinforcing existing foundation structures. Micro-piles are constructed with double tube excavation using by boring machine. After inserting a steel pipe into the hole, grouts are filled both inside and outside of pile. This paper describes the results of adhesion tests between pile and grout, field tests, compression loading tests, pull-out loading tests, and trail digging of compression loading test pile. By these test results, the following things could be confirmed. 1) It is possible that maximum adhesion stress between piles and grouts was estimated from unconfined compression strength of grouts, 2) It was confirmed that end improved soils were satisfied with diameters and strengths, 3) Covering depth of grout was more than 20mm, 4) Ultimate bearing capacity was evaluated the bearing capacity formula of micro-piles by cast in place pile in specifications for highway bridges.
Labor accidents frequently occur in trench excavations so that workers are buried of collapsed soil. Main cause of the accidents was luck of an installation of retaining walls to support the trench walls. In addition, workers failed to escape because they were not aware of an increase of the risk prior to failure. This study discusses on availability of simplified monitoring for prevention of the labor accidents. A full scale model test was carried out in a model ground composed of soft deposit of Kanto-loam and Compact strain meters of developed sensors were installed to measure increment of shear strain θ in shallow subsurface near the trench shoulder. Trench wall did not fail immediately after a completion of the final excavation, and 23 minutes of time lag existed prior to failure. The relationship between θ and the displacement shows good agreement in the increase. Similar reactions to the creep strain curve were observed in θ. A couple of minute time could be provided for escape by identifying either 2nd or 3rd creep. A clear increase of θ was observed at the shoulder area when the trench became unstable. It was clarified that the potential threat of trench failure can be detectable by the monitoring.
Rapid load tests were conducted with piles driven into a gravel bearing layer through a dense interlayer by various construction methods at Kawasaki port. It was confirmed that any tried method could drive the piles through the interlayer. And we could embed the piles into the bearing layer by hydraulic hammer. Base resistance and shaft resistance of piles were evaluated from the results of rapid load tests. Test results showed that the shaft resistance was significantly affected by the construction method. The base resistance was corresponded approximately to the estimated values obtained by the estimation equations commonly used in Japan.
In this study, the degree of saturation and the effective rainfall amount were reviewed in terms of the consistency of their time-dependent changes when two experimental embankments having different degree of compaction were collapsed by rainfalls. As a result, the consistency with the effective rainfall amount calculated with the use of the degree of saturation and a small half-value period was confirmed for the low density embankment, which presented progressive failure due to the increased saturation level. On the other hand, the relationship between the degree of saturation and the effective rainfall amount could not be confirmed for the high density embankment where dominant collapse form was gully erosion.