Stochastic consideration of consolidation settlement of Holocene clay layer in Osaka Bay

2014 ◽  
pp. 549-554
Author(s):  
K Oda ◽  
K Yokota ◽  
M Lee
Keyword(s):  
Clay Layer ◽  
Osaka Bay ◽  
Consolidation Settlement

scholarly journals Settlement Analysis of a Confined Sand Aquifer Overlain by a Clay Layer due to Single Well Pumping

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Wen-jie Niu ◽  
Zhenyu Wang ◽  
Feng Chen ◽  
Hongran Li
Keyword(s):  
Analytical Solution ◽  
Confining Pressure ◽  
Vertical Force ◽  
Clay Layer ◽  
Sand Aquifer ◽  
Consolidation Settlement ◽  
Single Well ◽  
Primary Consolidation ◽  
Pudong New Area ◽  
3D Finite Element Method

This paper proposes a simplified analytical solution to determine the primary consolidation settlement of a confined sand aquifer overlain by a clay layer due to single well dewatering. After single well pumping in a steady state, the Dupuit equation predicts the confined sand aquifer water head drawdown. The confining pressure on the underlain confined sand aquifer top surface is determined using the principle of vertical force equilibrium. Additional vertical stresses in each layer of the confined sand aquifer are then computed with the Boussinesq solution. The overall aquifer consolidation deformation is then determined with thee-lgpcurve from the one-dimensional consolidation test and the applied vertical stress with the integral method. The proposed analytical solution is validated using the ADINA software, where porous media are simulated with the Biot model and solved with the 3D finite element method. This proposed analytical solution is used to simulate the primary consolidation settlement due to well pumping, using the fourth confined aquifer in the Pudong New Area of Shanghai from 1980 to 1995 as a case study. The predicted settlement compares reasonably well with the actual measured settlement in Shanghai.

RELEASE OF NUTRIENTS FROM BOTTOM SEDIMENTS IN OSAKA BAY, JAPAN IN 2015

2017 ◽  
Author(s):  
Yukio Komai ◽  
Yukio Komai ◽  
Mana Sakata ◽  
Mana Sakata ◽  
Masaki Nakajima ◽  
...  
Keyword(s):  
Bottom Sediment ◽  
Bottom Sediments ◽  
Sea Water ◽  
Industrial Effluents ◽  
Ammonium Nitrogen ◽  
Water Release ◽  
Osaka Bay ◽  
The Core ◽  
Similar Range ◽  
Sea Area

Osaka Bay is the most polluted enclosed sea area, in which is located the eastern part of the Seto Inland Sea, Japan. There are four kinds of sources on loadings of nutrients to Osaka Bay, which are land including rivers and industrial effluents beside coast, ocean sea water, release from bottom sediment to sea water, and wet and dry deposition from air. The pollutant loadings inflowing from the land to Osaka Bay have been cut by various policies since 1970’s. The concentrations of nutrients in the inner part of Osaka Bay have showed an obvious decreasing tendency. However, the water quality in offshore sea has not satisfied the environmental standard on nutrients. We investigated the amount of nutrients released from bottom sediments. The core samples were taken at two stations in the inner part of Osaka Bay once a month from February to November, 2015. The core incubation experiment in laboratory was conducted for 24 hours according to Tada et.al. The concentrations of ammonium nitrogen (NH4-N) and phosphate phosphorus (PO4-P) were measured by an automatic analyzer. The flux showed similar range with the values investigated in 1986. The results suggested that the flux of nutrients from bottom sediments in the inner part of Osaka Bay has not decreased during summer season at least since 1985. Therefore, the contribution of release from bottom sediment on the nutrients budget would relatively become larger in inner part of Osaka Bay.

scholarly journals Groundwater salinity variation in Upazila Assasuni (southwestern Bangladesh), as steered by surface clay layer thickness, relative elevation and present-day land use

2019 ◽  
Vol 23 (3) ◽  
pp. 1431-1451 ◽  
Author(s):  
Floris Loys Naus ◽  
Paul Schot ◽  
Koos Groen ◽  
Kazi Matin Ahmed ◽  
Jasper Griffioen
Keyword(s):  
Land Use ◽  
Drinking Water ◽  
Coastal Region ◽  
Shallow Depth ◽  
Hydrological Processes ◽  
Groundwater Salinity ◽  
Clay Layer ◽  
Fresh Groundwater ◽  
Salinity Variation ◽  
Clay Layers

Abstract. In the southwestern coastal region of Bangladesh, options for drinking water are limited by groundwater salinity. To protect and improve the drinking water supply, the large variation in groundwater salinity needs to be better understood. This study identifies the palaeo and present-day hydrological processes and their geographical or geological controls that determine variation in groundwater salinity in Upazila Assasuni in southwestern Bangladesh. Our approach involved three steps: a geological reconstruction, based on the literature; fieldwork to collect high-density hydrological and lithological data; and data processing to link the collected data to the geological reconstruction in order to infer the evolution of the groundwater salinity in the study area. Groundwater freshening and salinization patterns were deduced using PHREEQC cation exchange simulations and isotope data were used to derive relevant hydrological processes and water sources. We found that the factor steering the relative importance of palaeo and present-day hydrogeological conditions was the thickness of the Holocene surface clay layer. The groundwater in aquifers under thick surface clay layers is controlled by the palaeohydrological conditions prevailing when the aquifers were buried. The groundwater in aquifers under thin surface clay layers is affected by present-day processes, which vary depending on present-day surface elevation. Slightly higher-lying areas are recharged by rain and rainfed ponds and therefore have fresh groundwater at shallow depth. In contrast, the lower-lying areas with a thin surface clay layer have brackish–saline groundwater at shallow depth because of flooding by marine-influenced water, subsequent infiltration and salinization. Recently, aquaculture ponds in areas with a thin surface clay layer have increased the salinity in the underlying shallow aquifers. We hypothesize that to understand and predict shallow groundwater salinity variation in southwestern Bangladesh, the relative elevation and land use can be used as a first estimate in areas with a thin surface clay layer, while knowledge of palaeohydrogeological conditions is needed in areas with a thick surface clay layer.

scholarly journals An investigation on dam settlement during and end of construction using instrumentation data and numerical analysis

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Behrang Beiranvand ◽  
Mehdi Komasi
Keyword(s):  
Numerical Analysis ◽  
Multivariate Regression ◽  
Initial Conditions ◽  
Horizontal Displacement ◽  
Behavioral Model ◽  
Critical Section ◽  
Earth Dam ◽  
Dam Construction ◽  
Good Match ◽  
Consolidation Settlement

AbstractIn the present study, using instrumentation data regarding vertical and horizontal displacement of the dam have been analyzed. Also, the largest and most critical section of the Marvak earth dam is modeled with the behavioral model of the Mohr–Coulomb by GeoStudio software. Numerical modeling of the dam has been done considering the actual embankment conditions and to analyze the changes of the immediate settlement during construction and the consolidation settlement just after construction and initial impounding. The outcomes of instrumentation and numerical analysis at the end of Marvak dam construction showed a settlement between 20 and 500 mm. The results show that the settlement will occur during the construction at the upper levels and the end of construction at the middle levels of the dam. By comparing observed and predicted data, multivariate regression and the explanation coefficient criterion (R2) was found to be R2 = 0.9579, which shows a very good correlation between observed and predicted data, and represents a good match for the settlement points and their location with the initial conditions of the design, and the behavior of the dam in terms of the settlement is found to be stable.

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