This paper presents a novel observational method, using data assimilation and soil-water coupled elasto-plastic finite element computation, for small and short-period construction projects for which observation data have not been utilized to revise the design during construction due to a limited budget. The proposed procedure is examined for its application to an actual construction project. Firstly, the final settlement of the structure is evaluated using the identified material properties by both data assimilation, using the observed settlement, and in situ physical soil tests. Secondly, the probabilistic distribution of the final settlement of the structure is obtained from the identified values and the probabilistic density function of the parameters by data assimilation using observations conducted during construction. To reduce the settlement at the final stage of construction, estimated by the probabilistic distribution not to exceed the performance criterion, a construction sequence has been adopted from among the available design alternatives.
When deciding the priority of possible countermeasures, it is important to understand the conditions and factors of water shortage in irrigation canal system both objectively and quantitatively. In this study, we organized information on irrigation canal system, including regulating reservoir according to the spaces and times, which are in turn divided by spatial and temporal aspects, namely, (1) satisfaction of users on the adequacy of supplied irrigation water and (2) indicator values for 3 assessment items, adequacy, reliability, and vulnerability. As a result, we have reached three important conclusions. (1) In sections where the satisfaction was low, 1) the amount of intake flow of lateral canals was less and 2) there was a day which the flow was less. (2) The shortage of intake flow was considered to be because of a shortage in the reliability of the main canal water flow according to the increasing demand. (3) The use of vulnerability together with reliability was considered important for deciding the priority of possible countermeasures. Further, we consider that a combination of diagnoses that could aid in identifying the sections having usage issues regarding the main canal water flow and detailed diagnoses of these sections would result in effective cost reduction.
Time domain transmissiometry (TDT), a method of measuring transmitted broadband signal in microwave frequency, was used to measure volumetric water contents (θ) and liquid-phase electrical conductivities (σw) in sand. The θ and σw were determined independently with travel time and amplitude of impulse-signal transmission, although the determination of both θ and σw with saline sand (θ ≥ 0.32 m3 m-3 for σw = 1.19 S m-1) was difficult due to the loss of transmitted signals. Judging from the versatility and the simplicity of signal analyses, we believe that the TDT technique would be a more convenient method than time domain reflectometry (TDR) to monitor θ and σw in soils.
We obtained breakthrough curves of humic acids with different molecular weight (SHA, 30,000 - 100,000; LHA, 100,000 - 300,000) through the column packed with glass beads with various NaCl concentrations. Each breakthrough curve of each humic acid reached almost a stable plateau at which the relative concentration was less than unity. The relative concentrations at each plateau decreased with an increase in the NaCl concentration. From the experimental study, dimensionless deposition rate constants and collision efficiencies of humic acids were calculated. Collision efficiencies were plotted as a function of NaCl concentration to draw a colloidal stability curve. In both humic acids, the obvious boundary points, which were known as the critical deposition concentration (CDC), were obtained from the colloidal stability curve. The value of CDC of smaller molecular weight fraction was higher than that of larger one. In the slow deposition condition, the slope of the stability curve of larger molecular weight fraction was steeper than that of smaller one.
In this study, we selected Khovd, Arkhangai, Dornod, and Umunugobi provinces respectively in 4 pastoral districts of Mongolia for carrying out the following analysis. The regional characteristics of livestock damage caused by variations in weather conditions were clarified by analyzing the relationship between the meteorological factors and mortality of sheep which was major livestock in the whole county. This analysis showed the following results: 1. Livestock was damaged by the heavy snowfall in winter in all provinces. 2. In Umunugobi province of the highest-temperature and the most drying area, many sheep starved to death in winter when the growth of pasture was degraded by high temperature and low rainfall in summer, and its mortality also increased by cold rainfall in spring and autumn seasons. 3. It caused livestock damage that the drinking water in winter was insufficient by a decrease in snowfall of March in Umunugobi and Khovd provinces with less precipitation. 4. In Arkhangai province with the lowest temperature, livestock was damaged by low temperature in winter. 5. In Dornod province, the livestock was damaged by long-term blizzard in April.
Batch sorption test and selective sequential extraction were conducted for two types of bentonite mixture using basalt soil and Andosol to examine the effect of salinity for their lead sorption abilities. Increase in salt concentration of solution decreased the lead sorption of the soil mixtures. Particularly exchangeable phase of lead sorbed in basalt soil mixture decreased with the increase in the salt concentration. Due to the high buffer capacity of allophane contained in Andosol, Andosol mixture exhibited the higher lead sorption ability than basalt soil mixture. Buffer Prediction of lead leaching by convection-diffusion equation showed that the high salt concentration increased the mobility of lead in the clay liner. The leaching speed of basalt soil mixture was the three times higher than that of Andosol mixture. These results suggest that Andosol is effective material for reduction of lead mobility in clay liner.
In complex irrigation canal systems, degradation in reliability of water supply at one point may be caused by some factor at another point in the network. By analyzing the spatial continuity of failures (the conditions in which the actual values of discharge etc. are lower than required) in a canal and evaluating the influence of such failures on cultivation, we demonstrate a methodology for evaluating the influence of failures at each point on the degradation in reliability of the irrigation canal system. We employed this methodology in the main canal by using upstream controls. In addition, we showed that some specific points had a great influence on degradation in reliability of the main canal. Our results show that points requiring detailed diagnoses and conservation measures can be located using this methodology.
Nonferrous metal slag is a circulating material which is a byproduct of nonferrous metal refining. Among these, copper slag and ferrous nickel slag (FNS) are already made Japanese Industrial Standard as aggregate for cement concrete and used. However, some are difficult to utilize due to their manufacturing process, particle diameter or shape and in particular much of the fine powder FNS is stocked. On the other hand, fine powder iron oxide generating as collection dust is used as soil stabilizer mixed with slaked limemainly in the Kyushu region. However, the strength developability of the stabilizer (Fe lime) has been founded through experience and remains to be investigated regarding the improvement effect for various ground materials. In this study, utilization of fine powder FNS as soil stabilizer mixed with slaked lime is proposed and the improvement effect for particular soil of the Kyushu region is evaluated along with the strength developability, environmental safety and economical aspects by comparison with Fe lime. As a result, the usefulness as the quality of soil stabilizer of the fine powder FNS was recognized.
A prototype loading test apparatus that can imitate situations of a concrete lining of an irrigation tunnel with a hollow behind it was fabricated to investigate the mechanism of cracking commonly observed on spring lines in sidewalls of irrigation tunnels. In addition, effectiveness of a backfill grouting method to prevent further cracking and deformation in concrete lining was examined. In the cases with a hollow behind the arch, test specimens of scaled concrete lining showed outward displacement on their crowns due to the lack of vertical load, as well as inward displacement in side walls by horizontal load. This deformation in side walls led cracking on the spring lines, as in the cases of real irrigation tunnels. It is confirmed that a hollow behind the arch remarkably reduces the load bearing capacity of concrete lining. It becomes smaller with a larger hollow, reducing the difference between the cracking and ultimate loads of the lining. The results of experiments simulating a backfill grouting hollows behind the linings showed a strong possibility to reduce abnormal deformation of linings, as well as to increase cracking and ultimate loads greatly.
Estimation of the population size of oriental weather loach (Misgurnus anguillicaudatus) was attempted using the removal method and the mark-and-recapture method in paddy plots in Kaminokawa City, Kawachi County, Tochigi Prefecture in 2007 and 2008. Removal surveys were conducted four times in each of the three study sites (950 m2, 950 m2 and 1,000 m2 in area) established in two paddy plots from 15 June to 6 August, 2007. The mark-and-recapture surveys were done twice in each of two sites (1,900 m2 and 1,000 m2) established in the two paddy plots from 15 June to 3 August, 2008. The estimated population size (population density; individuals per 1 m2) excluding unreliable estimation values, by the two methods ranged from 538 (0.54) to 1,526 (1.61). Based on these results, several proposals on the estimation method of the loach in paddy fields are given.
We discussed the amplification characteristic of ground motion obtained on the reclaimed landfill in port of Tokyo during the 2011 off the Pacific Coast of Tohoku Earthquake. The characteristic site period increased lineally with the depth to base layer. The amplitude ratio of maximum acceleration and the predominant frequency tended to decrease according as the characteristic site period increased. Also, the peak acceleration response spectrum ratio tended to decrease according as the characteristic site period increased, but the predominant period tended to increase.
Capacitance soil moisture sensors have been widely used to measure soil water content. However, their accuracy for field application is rarely investigated in comparison with other conventional methods. To evaluate the performance of a capacitance soil moisture sensor (EC-5, Decagon device), two side-by-side soil moisture profile measurements, which were acquired from 70 cm depth using the EC-5 and tensiometers under film mulching are compared from July to September in the years 2011 and 2012 at an Andisol site in Japan, were compared. Soil moisture readings by the EC-5 coincided with those by tensiometers in the moisture range below 78 kPa. Tensiometers could not measure moisture levels above 78 kPa; however, the EC-5 was capable of measuring moisture levels above 78 kPa. Parameters for irrigation scheduling (daily consumption rate, soil moisture extraction patterns and total readily available moisture) were estimated using the data acquired from both the EC-5 and tensiometers. These parameters almost coincided with each other, except in the dry period. Therefore, we concluded that the EC-5 can accurately measure soil moisture in the field and provide useful parameters for irrigation scheduling.
Cesium (Cs) adsorption and desorption properties of soils in southern Ibaraki prefecture of Japan and selected clay minerals were examined using a stable isotope 133Cs. When 27 mL of 1 mg L-1 Cs was added to 1.0 g of soil, bottom mud of Lake Kasumigaura adsorbed 97 %, and Andisol topsoil adsorbed 88 % of the Cs. When the Cs adsorbed soils were washed 3 times with water, the Cs adsorption percentage of Andisol topsoil decreased to 82 %. Further washing of the soil with 3 times1 M KCl decreased it to 75 %. Considering that the K concentration used was thousand times high compared with that of an agricultural field, the effect of K fertilization on Cs elution from soils was suggested to be negligible. The distribution coefficient (Kd) of Cs in Andisols and bottom mud of Lake Kasumigaura increased with decreasing initial concentration of Cs within the range of 0.01~10 mg L-1. Because the actual concentrations of 137Cs in contaminated soils were several orders lower than those tested in this experiment, it was clear that the radioactive cesium would be adsorbed on such soils more firmly than the data found in this experiment.
Rainfall-runoff characteristics in upland field catchments in south Kyushu district need to be studied in order to conserve the field catchments, because this district has areas under high erosion risk due to heavy rainfall and erodible soil. We investigated the rainfall-runoff characteristics in the field catchments by using hydrological data collected by measuring runoff discharge and rainfall with an H flume and a rain gauge, respectively, in each catchment. The runoff coefficient of the rational formula showed a maximum value of 0.096 for the catchment with Kuroboku soil on Shirasu Plateau. By contrast, the coefficient showed a maximum value of 0.50 when plastic mulching was performed over the catchment at a coverage rate of 45%. The runoff coefficient for the catchment with weathered Kunigami soil and low permeability on the island of Tokunoshima showed a maximum value of 0.45, while the coefficient for the other catchment with high permeability in a limestone area on the same island showed a maximum value of 0.033. Flood concentration times in these catchments ranged from 10 to 30 min and did not vary significantly among the catchments. In addition, no high correlation could be found between the flood concentration time and effective rainfall intensity in the study catchments of less than 5 ha.