Title

INFLUENCE FACTORS ON THE LABORRATORY TESTING OF GEOTEXTILES UNDER CONTROLLED ENVIRONMENT

Author(s)

D.T. Bergado, S. Youwai and J. Maneecharoen

Abstract           [Full text PDF]

In order to investigate the influence factors affecting index and enginnering propertiesa of geotextiles under controlled environments, different tests were conducted using both heat-bonded nonwoven and needle-punched nonwoven geotextiles, namely: apparent opening size (AOS), wide-width tensile strength, permittivity, transmissivity, adn puncture resistance. The effect of humidity on the pore size of the samples was also investigated. To check whether the clamping system has an effect on the strength of geotextiles, over 240 tests were conducted. The presence of air bubbles in water and its effect on the permittivity and transmissivity of geotextiles were also verified. Also investigated were the effects of higher strain rate and displacement rate on the tensile strength and puncture resistance, respectively.The results indicate that decreasing humidity slightly increased the AOS; higher strain rate and the use of hydraulic clamp increased the wide-width tensile strength; using de-aired water largely improved the permittivity and transmissivity; and increasing the strain rate decreased the puncture resistance. The effects of humidity and oxygen content were more pronounced and obvious in the case of needle-punched geotextile compared to heat-bonded nonwoven geotextile.

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Title

AUTOMATION OF THE RIJNLAND STORAGE BASIN, THE NETHERLANDS

Author(s)

w. Schuurmans, P.E.R.M. van Leeuwen and F.E. van Kruiningen

Abstract           [Full text PDF]

The project "Automation of the storage Basin Rijnland" (ABR), was finalised at the beginning of the year 2000, that is three years later than originally planned. The project has resulted in an automatic control system for four drainage pumping stations (total capacity 150 m^3/s) and an intake structure. The system can be operated with or without the intervention practice. The system is currently running according to expectation, but its design has been adjusted drastically.

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Title

BEHAVIOR OF THEORETICAL CURVE NUMBERS WITH RESPECT TO SOIL AND RAINFALL PROPERTIES

Author(s)

T.Y. Gan

Abstract           [Full text PDF]

A dimensional analysis fails to obtain a universal, dimensionless relationship between the maximum retention potential (S) of the Soil Conservation Service (SCS), runoff curve numbers (CN), and saturated hydraulic conductivity K_s, sorptivity, rainfall parameters, surface runoff, and soil moisture. Next, both S and the theoretical CN (CN_T) were calibrated based on the numerical solutions of Richard's equation applied to nomogeneous soil columns. Results show that S and CN_T are directly related to soil but inversely related to rainfall properties. As a temporally-lumpe model, CN generally estimated lower cumulative infiltration than that of Richard's equation; and in practice, the CN method may perform poorly if (1)the Antecedent Moisture Conditions (AMC) is low, (2)the initial rainfall is much higher than K_s which leads to Horton overland flow, or (3)the rain pulses after the initial abstraction is satisfied are small. Before applications, adjustments of CN_T with respect to the standard CN of fallow/idle land to reflect the effects of landuse, land treatment, and hydrological conditions are recommended.

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Title

DEVELOPMENT AND HUMAN SETTLEMENT IN SAGA AND SHIROISHI PLAINS BY RECLAMATION

Author(s)

M.R. Madhav, N. Miura and T. Igarashi

Abstract           [Full text PDF]

The paper describes a case study of development of a very unique region in Japan, consisting of the Ariake bay and the Saga plain, which is subjected to about 6m of tidal fluctuations and had been reclaimed from the sea over a period of centuries. The sequences of land development, reclamations, developments of water systems, dwellings, etc. are traced. The distinct characteristics of hydrology, irrigation and water management and urban drainage are described. Lastly, the serious problem of subsidence due to excessive pumping of ground water mostly for irrigation but also for industrial and domestic use is high-lighted. The human settlements in this region have evolved alogn unique patterns of designs especially of the water sysytems and the houses in spite of being subjected to construction on very soft soil, being buffeted by typhoons and subsidence.

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Title

AN OBSERVATIONAL PREDICTION OF LAND SUBSIDENCE FOR A GIS-AIDED MONITORING SYSTEM OF GROUNDWATER LEVEL

Author(s)

S. Murakami, K. Yasuhara and N. Mochizuki

Abstract           [Full text PDF]

A simplified method for observational prediction of land subsidence based on settlement versus time records being previously observed at locations of the objective area was proposed in the present paper for use of the geographic information system (GIS). However, no consideration of ground water level (GWL) variations was taken into proposal of the method. The present paper, however, attempts to realize use of this time series analysis. Settlement variations over time predicted using the proposed two methods available for cases with and without consideration of GWL fluctuation were compared with those observed at locations in the objective area. In comparison with a method which ignores GWL fluctuation, better agreement was recognized between predicted adn measured settlement versus time settlement acceleration over time during water shortage periods. Result predicted using the proposed method are displayed as hazard map using the GIS. Based on the GIS application map, a possible monitoring system is presented for groundwater usage optimization.

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Title

INVESTIGATION OF SHORT-TERM RUTTING PROCESS OF FLEXIBLE PAVEMENT SYSTEM WITH GEOGRID – REINFORCEMENTS BY HOMOGENIZATION METHOD

Author(s)

B. B. Budkowska and J. Yu

Abstract           [Full text PDF]

This paper presents the investigations on short-term rutting that is developed in standard and geogrid–reinforced flexible pavement structures. The main source of the supporting experimental data acquisition on studied type of rutting was provided by laboratory records that had been published in technical literature. The experimental research focused on the development of clear grounds indicating that geogrid-reinforcement is the effective method of reduction of permanent deformations of the pavement system. The comprehensive discussion on the laboratory results showed that the placement of geogrid–reinforcement at various levels of base layer, generated different effects in various parts of the pavement system. The numerical investigations are focused on determination of modulus of permanent deformations Ep for each layer contributing to the pavement structure. They are considered as being the functions of the number of load repetitions N. The constitutive law incorporated for this purpose is modified 3-D Hooke’s law that involves the modulus of permanent deformations. The identification of Ep is conducted in the framework of homogenization method which assumes the homogenity and isotropy of each layer. The fact of irreversibility of permanent deformations is taken into consideration by geometry’s continuous updating process. The determination of Ep requires full information on increments of permanent displacements of control points corresponding to each consecutive load repetition. The numerical investigations are performed for axisymetric geometry by means of the finite element analysis (FEA) program ABAQUS (1998). To guarantee the correctness of the results obtained, the problem that was explored was subjected to verification studies by means of the KENLAYER (1993) program, that was suitably adjusted for this purpose.

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Title

APPLICATION OF ANN FOR RESERVOIR INFLOW FORECASTING USING SNOWMELT EQUIVALENT IN THE KARAJ RIVER WATERSHED

Author(s)

H. R. Eslami and K. Mohammadi

Abstract           [Full text PDF]

Three different methods were used to predict the spring inflow into the Amir Kabir reservoir, which is located near Tehran, Iran. The spring inflow accounts for almost 60 percent of annual inflow to the reservoir. Utilizing the results of an artificial neural network (ANN) model, the inflow to Amir Kabir reservoir is predicted. It will be compared with two other methods: ARIMA time series and regression analysis between some hydroclimatological data and inflow. Using the thirty years of observed data proved that the ANN has a better performance than that the other methods have.

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Title

SEISMIC ANALYSIS SYSTEM OF BRIDGE PIER WITH PILE FOUNDATION IN ARIAKE SOFT CLAY REGION

Author(s)

R. Mahmudur , G. Aramaki, Koga Katsuki and T. Ohtsuka

Abstract           [Full text PDF]

In our earlier paper which appeared in IALT, it is pointed out that design of bridge pier with big seismic loading needs special attention such as consideration of ground displacement, soil-pile interaction effect etc., when foundation piles penetrate through soft clay layer and ground displacement largely depends on soil shear wave velocity, Vs & strain dependence of G/G0. The Road Bridge Code in Japan states that shear wave velocity, Vs can be considered 50 m/sec in soft clay having SPT N-value zero. In this study, seismic analysis was carried out considering three cases: Case I using measured Vs value, Case II where Vs = 50 m/sec for all layers and Case III where Vs is calculated from the Railway Bridge Standard in Japan formula for the soft clay layer. Both of Penzien model and single input model analysis were performed. The bridge structure used in the analysis was first designed by Seismic Co-efficient Method and Ductility Design Method. In dynamic analysis, non-linear elasto-plastic material behavior was considered for piles. Linear pile behavior case was also performed. In the former case responses mainly displacement and bending moment were found less compared to linear case. Responses in Case II were found much higher than other two cases and would result very uneconomical design. Penzien model analysis system with non-linear pile material consideration is proposed for analysis of bridge pier with pile foundation in Ariake soft clay region. It is emphasized that Vs and also strain dependence of G/G0 be precisely measured in the soft clay region because of their big influence in seismic analysis in soft clay region. Difference between responses in Case I and Case III were found small. In the unavailability of measured data, Vs may be calculated by the Railway Bridge Standard formula.

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Title

EFFECT OF DRAINAGE GALLERY DIMENSIONS ON THE UPLIFT FORCE OF A GRAVITY DAM

Author(s)

M. A. El-Razek and M. M. A. Elela

Abstract           [Full text PDF]

Uplift pressure on the floor of the gravity dam affects the stability of the dam. Therefore minimizing the uplift pressure force can be achieved by constructing a drainage gallery. In the present work, three parameters of the drainage gallery are studied experimentally on a sand model of gravity dam to determine their effect on the total uplift force acting on the floor of the dam. These parameters are the diameter of the drainage gallery (d), spacing of the drainage gallery in the longitudinal direction of the dam (L), and the penetration depth (h). It is found that, the penetration depth of the drainage gallery is more effective in reducing the uplift force than the other two parameters. The average values of reduction in the uplift force attributed to the change of d, L, and h accounted to about 11 %, 25 %, and 40 % respectively.

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Title

FIELD PROPERTIES AND SETTLEMENT CALCULATION OF SOIL-CEMENT COLUMN IMPROVED SOFT SUBSOIL – A CASE STUDY

Author(s)

J. C. Chai , S. Y. Liu and Y. J. Du

Abstract           [Full text PDF]

The unconfined compression strength, standard penetration test (SPT) results for soil-cement columns and the field loading tests results of the composite subsoil at Lian-Yun-Gang section, Xu – Lian expressway, China, were presented. The methods for calculating the settlement of the soil-cement column improved soft subsoil were discussed. It is recommended that the stiffness of the “slab” on the top of the improved subsoil should be considered in selecting the settlement calculation methods. It is suggested that in the case of a flexible “slab”, the equilibrium method for the improved layer and the average stress method for the underlying unimproved soft layer are preferred, while in the case of a stiff “slab”, the average modulus method for the improved layer and the combined method for the underlying unimproved layer are preferred. Finally, the settlements of the soil-cement column improved subsoil at Lian-Yun-Gang section were evaluated by the suggested methods and compared with the field data. The stress concentration ratio (n) is back-calculated, and it showed that n value increased with the increase of the area replacement ratio.

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Last Updated: January 30, 2005