New Frontier of Environmental Geotechnical Engineering
Outline of the Research
Takahashi laboratory is now studying the new environmental geotechnical engineering research. Specifically, we are studying the following researches:
1. Study on development of highly-functional rooftop planting soil us using water purification sludge:
We are trying to spread the rooftop planting widely. Furthermore, we would like to contribute to restrain the heat island and to create the healing space by spreading the rooftop planting
2.Study on development of planting soil for rock slope:
The goal of this research is to contribute the environmental conservation and landscape restoration by planting on the rock slope in mines and quarries
3. New Drilling Technology for Lunar Ground for In-situ Resources Utilization(ISRU)
Recent Research Topics
- (1) Development of Highly-Functional Rooftop Planting Soils from Water Purification Sludge
- (2) Rock Slope Planting : Utilization of Wooden Chips made of Logged Trees
- (3) Development of Highly-Functional Banking Materials by Integrating Several Wastes
- (4) New Drilling Technology for Lunar Ground for In-situ Resources Utilization(ISRU)
(1) Development of Highly-Functional Rooftop Planting Soils from Water Purification Sludge
Takahashi laboratory is studying the new recycling system of high-water content sludge. The feature of this system is that the dewatering process is not necessary. In other words, the soil modified by this new system contains a large amount of moisture inside. Therefore, the possibility to use this soil as planting soil is very high.
We have developed the artificial soil for roof-top planting by using the water purification sludge. The developed soil has several features such as lightweight, high holding ability of moisture, high holding ability of fertilizers and high permeability. We set a bet of flowers along the visitor's tour course in the water purification plant in Sendai city, Miyagi Pref. Japan in order to publish our research achievements. Now, we are investigating the optimum processing method from the view point of soil physics. The target of this research is to develop the new artificial soil with satisfying all parameters such as lightweight, high holding ability of moisture, high holding ability of fertilizers, high permeability and three-phase(solid, water, air) distribution.
Artificial soil developed in our laboratory using water purification sludge. The feature of this soil is flakiness.
An example of roof-top planting(Moniwa Water Purification Plant, Sendai City, Japan)
An example of roof-top planting(Oita City Hall, Japan)
(2) Rock Slope Planting : Utilization of Wooden Chips made of Logged Trees
We are carrying out a cooperative research on a new planting method for slopes by using wooden chips and fiber-rich planting soils. This is a zero emission method which utilizes the wooden chips made of stump pulling, branches and leaves, logged trees and fiber-rich planting soils produced from water purification sludge. The new planting soils which the fibers contained in fiber-rich planting soils and wooden chips intertwined complexly are made. The feature of this new planting soil is high durability for the rainfall. Furthermore, if the length of the wooden chips is controlled less than 30mm, it is possible to use the conventional mortal spraying machine. Consequently, a large cost reduction will be possible. Now, we are thinking to apply this new planting soils to the rock slope planting in limestone mines and crushed rock quarries.
Chipping of stump pulling, branches and leaves and logged trees
Mixing of wooden chips and fiber-rich planting soils
Spraying the new planting soils. The use of conventional machine is possible.
After 60 days
(3) Development of Highly-Functional Banking Materials by Integrating Several Wastes
Fiber-cement-stabilized soils developed in Takahashi laboratory by cooperative research with Mori Institute for Environmental Technology have several features such as high failure strength, high failure strain, high durability for drying and wetting, high durability for freezing and thawing. Therefore, it can be considered that fiber-cement-stabilized soils are the best for reinforced materials of banking. However, as this soil is produced by mixing a large amount of paper fragments with the sludge, this soil is lightweight compared with normal soils. The lightweight soil is good for rooftop planting, but is not good for reinforced materials of banking because the lightweight soils are easy to float in flooding. Therefore, we are trying to increase the soil density by adding some other wastes such as RC aggregates and slag with keeping the above mentioned features of fiber-cement-stabilized soils. We have already conformed the best addition rate of RC aggregates and slag.
Sliding of the bank by earthquake
X ray CT Image of fiber-cement-stabilized soils with RC aggregates
(4) New Drilling Technology for Lunar Ground for In-situ Resources Utilization(ISRU)
In order to construct the base of operation on the lunar surface, it is indispensable to promote the infrastructure. However, a huge amount of money is necessary if the materials and energy for infrastructure construction are transported from the earth. Therefore, ISRU(In-Situ Resources Utilization) has a lot of attention recently. ISRU is an idea that necessary materials and energy for infrastructure are made by using the resources on lunar surface. In order to realize ISRU, the sensing technology which investigates the distribution and amount of resources, the handling technology which digs and excavates the lunar regolith and processing technology which produces the desired materials and energy are necessary. Takahashi laboratory belongs to the handling group and is carrying out the fundamental study on lunar drilling. In this research, a technology of small diameter excavating machine (mole robot) is applied.
Image of ISRU (from Mr. Jerry Sanders/NASA-JSC)