This paper describes the use of geosynthetics in lowland area. Soft alluvial clay deposits in this area in 5m to 25m depth, where land subsidence occurs due to ground water pumping. As the countermeasure for differential settlement caused by soft deposit and land subsidence, geosynthetics have widely used in this lowland area. Eight case-studies are illustrated, in which prefabricated band-shaped drain, filter, polymer grid, and glass grid are used, and the results are discussed.

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Short fiber-reinforced earth construction methods in which non-continuous geosynthetic filaments are mixed uniformly with soil aggregates are being developed recently for the purposes of improving the mechanical properties of shear strength and strain-dependent toughness of the reinforced soils. In addition this method has some beneficial functions in wide-range environmental applications such as the re-use of poor surplus soils produced in the construction sites and stabilizing the steep slopes providing the vegetation base. At present insufficient knowledge is available regarding to effects of material, shape, size, flexibility, surface fiction and other fundamental properties of short fiber on the mechanical behavior. A newly developed short fibers with several side branches (so called ribbed-type fiber) is employed in order to not only improve their reinforcement effects but also to be able to exclude the fibers without great effort in case of reuse of the soils. In this study effects of the mixing rate of the fibers on the reinforcing mechanism are investigated using an unconfined compression test and a large box shear test (box size: 320×400×240mm).

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Study on the pullout resistance was made on the model geogrids. The first sense, special attention was directed to see the effects of the shape of geogrids. The effects of stiffness of the geogrid were investigated in the second sense. It turned out that the geogrids of the same horizontal area, stiffness and thickness had the same friction angle between soil and geogrid, but apparent cohesion, displacement and strain distribution were different. Three model geogrids had the same shape and surface friction, but the stiffness was different. The peak pullout resistance of the stiff geogrid was obtained at the small pullout displacement. Difference in stiffness especially affected at the beginning of the pullout test.

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The isochronous theory is popular in modelling the time-dependant strength and deformation characteristics of polymer geotextile for the design of reinforced soil structures. According to this theory, the tensile load of reinforcement is a function of instantaneous strain and elapsed time. Thus, the design strength would reduce monotonously with time elapsing. It is shown that the isochronous concept is not able to explain the tensile behavior of reinforcement observed in the present study, in particular the behavior after loading is restarted at a constant strain rate after a creep and relaxation. Experimentally observed time dependency of tensile characteristics of geogrid is reported, and an analytical simulation of the tension test results on geogrid by one type of three-component model was performed. The results of an experimental and analytical investigation showed that the proposed constitutive model is relevant to simulate the time-dependent deformation and strength characteristics of the tested geogrid.

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Retained tensile strength of geogrids, which were used as the reinforcement of reinforced soil retaining walls and abutments with rigid facing for a railroad line, are tested after almost 8 years of service. The geogrids were made from vinylon nets coated with polyvinyl chloride resin and those were selected because of their higher resistance to alkaline of recycled concrete stone that was used as the filling material. Ten specimens are taken from each upper, middle and lower position of the retaining walls and abutments, respectively. The results of tensile strength tests are shown in relation between the tensile strength and the strain at failure. Also each tensile strength from different positions is arranged to show the average tensile strength in kN/m considering with the deviation of the test results. The result shows that although there are strength differences among the positions of the geogrids, each retained tensile strength of the geogrids is well above the guaranteed tensile strength of the products.

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Reliability analysis method for reinforced soil wall with seismic hazard information was examined. In the parent paper, outline of the method are shown and effects of design value uncertainty, reinforcements layout and seismic hazard information is considered based on analysis results. Established results are as following. (1) The developed method evaluates stabilities against six failure modes with considering uncertainties of design values and seismic load. (2) Effects of uncertainty for design values of backfill soil is more enormous than that for reinforcement (3) Effects of reinforcements layout depends on type of failure mode. (4) In the case that stronger seismic load is assumed, failure probability for sliding or overturning of reinforced zone becomes larger.

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Centrifuge tilting tests were conducted to study the effects of geogrid properties on seismic stability of reinforced embankment. It was found that the stability of the embankment was influenced by shape and stiffness of the geogrid. Deformation of the reinforced area was especially limited within the confined area with the geogrids of high stiffness. Therefore, the steep embankment could be stable. Stability analyses were made by using the two-wedge method. Failure mode of the embankment and the horizontal seismic coefficient at failure were well expressed in the analysis by using the reduced pullout resistance, which was determined from results of pullout tests.

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The preloaded and prestressed (PLPS) reinforced soil method with a ratchet system aims at preventing reduction in the prestress even when the backfill exhibits compression. A series of shaking table tests were perfumed. In one of the model tests with a ratchet system that worked imperfectly the prestress decreased against high input motions. Despite the above, the behavior of the model was nearly the same as the model with a system that worked nearly perfectly keeping the minimum prestress constant to the initial value. The most important function of the ratchet system is to fix the tie rod rigidly to the reaction block whenever the backfill tends to expand.

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The 1995 Hyogoken-Nanbu Earthquake caused serious damage to conventional type abutments for railways. They suffered large relative settlements between the abutment and the backfill, while even a small relative settlement would have endangered safe operation of train running. In this study, a series of shaking table tests on reinforced abutments were carried out in order to develop a new type abutment which can resist satisfactorily against a high intensity of input motion such as Level 2 earthquake. The proposed types of abutment in this study are a) reinforced abutment with cement-treated backfill, b) reinforced small abutment resting on cement treated and reinforced backfill, and c) preloaded and prestressed (PLPS) reinforced backfill with a retchet system. The experiments revealed that the seismic stability of these abutments are much higher than conventional type abutments and they maintained sufficient stability against a very high intensity of input motion.

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Model shaking tests using an irregular base shaking were performed to investigate the failure mechanism and seismic stability of five types of soil retaining walls (RWs) situated on slope. Conventional leaning-type and cantilever RWs exhibited brittle failure when subjected to a relatively low base acceleration. A reinforced soil RW showed ductile and highly seismic-resistant behavior. On the other hand, a leaning type RW and a reinforced soil RW with nails in the backfill and slope exhibited the highest seismic stability, showing small displacements even when subjected to a base acceleration higher than 1g. It was found that nailing could be one of the best ways to stabilize existing leaning RWs on slope, and reinforced soil RWs with nails could be the most stable ones as newly constructed RWs on slope.

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The constructions on steep slope are limited by its locations or structures by topographic conditions. Conventionally, it becomes large construction because it requires strong basement. Then, it is requested to invent new construction method to make it easy construction on steep slopes. The reinforced earthfill is effective method compared with conventional method with rigid structure. However, stability of boundary between steep slope and earthfill, distribution of force acts on reinforcement and difference by rigidity of facing are not clear. Model tests, reinforced earthfill with anchor on steep slope, were conducted. As a result of tests, the change of earthfill stability had confirmed by position of anchor, the rigidly of reinforcement or rigidly of facing.

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The load-settlement behaviour and bearing capacity of a strip footing on reinforced sand was simulated by a nonlinear elasto-visco-plastic FEM analysis incorporating an elasto-viscoplastic constitutive model for sand that was developed to have a stress path-independent work-hardening parameter based on the modified plastic strain energy concept. The constitutive model has been modified to take into account the nonlinear viscous property of sand based on a three-component model consisting of a hypo-elastic component connected in series to a combination of a non-linear inviscid and viscous components connected to each other in parallel. The model ground was made of air-dried dense Toyoura sand, which was either unreinforced or reinforced with different lengths, numbers of layers and vertical spacings of layers of linear, tensile reinforcing members placed horizontal beneath a strip footing. Load-settlement relationships obtained by the FEM analysis were well comparable with those from the physical experiment. Although the peak footing load obtained by the FEM analyses was slightly larger than the measured value, the effects of reinforcing patterns and progressive failure of model ground with a development of shear bands observed in the tests were simulated very well.

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The authors have experimentally examined the reinforcing effects in geogrid-reinforced soil and have evaluated it quantitatively. As a result, it was made clear that the reinforcing effect are expressed by the sum of the tensile effect and the confining effect. In this paper, two-dimensional small model tests for simulating the geosynthetics-reinforced retaining wall have been performed to clarify the mobilized confining effects. The reinforced effects are estimated by the changes of the active earth pressure in the retaining wall without and with geosynthetics-reinforcement. Relationship between the changes of the active earth pressure and the confining effect parameter has discussed in connection with the Mohr-Coulomb failure envelope in reinforced soil.

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Based on a proposed method to evaluate the confining effect on geogrid-reinforced soil, the confining effect is introduced into a failure criterion on the reinforced soil and stress condition of reinforced soil at failure is expressed by using Mohr's stress circle. On the proposed failure criterion the tensile force of geogrid is assumed to be equal to the Rankine's active earth pressure. As a result of comparing the two values of horizontal earth pressure which is calculated from the failure criterion and measured on large-scale geogrid-reinforced soil wall, the validity of the proposed failure criterion is clarified.

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Among various kinds of soil reinforcement methods, as a foundation ground treatment measure for reinforced earth method, a method to wrap filling materials such as sands or crushed stones with a geogrid was adopted. By this method, it was expected that the rigidity of a reinforced body would be enhanced due to the combination of a geogrid and filling materials, and effectiveness would be increased in the improvement of bearing capacity of a structure, the prevention of irregular subsidence, and the decrease of the degree of subsidence.
It had been confirmed by table tests that in the reinforcement of soft ground, deformation characteristics of a reinforced body greatly affects the mechanism of bearing capacity. However, there are only few reports that describe the confirmation at actual construction sites and the deformation conditions of a geogrid. In addition, it is actual situation that even though various design techniques were proposed, a definite design method has not been established. In order to confirm the deformation characteristics of a reinforced body and the effects, the authors conducted the measurement of the degree of deformation of a whole reinforced body using a water-gage and the measurement of tension working on a geogrid using a tension-meter. This paper presents the deformation characteristics and the effect of a reinforced body obtained by this experiment

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A new type of reinforced earth wall was developed, using improved soils combined with geogrid. It had been carried out pull-out tests of the geogrid in improved soils, loading tests on the model and the trial construction of a new type of reinforced earth wall. In this papers, we report the distribution of earth pressures, subugrade reactions and the strain of geogrid of its wall.
As a result, it was confirmed that the earth pressures acting on the concrete panel are negligible due to the effect of the improved soils. In addition, geogrid was found to be subjected to tensile strains, indicating that it is effective in contributing the stability of its wall of this kinds.

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For construct of railway embankment on soft ground, we used deep mixing method together with geogrid to decrease settlement of the ground. Then, we need to understand the behavior of the embankment constructed by this method, caused by static load and dynamic load. So, we did dynamic loading test using two full-scale embankments on site. We will propose a rational method of design for embankment using deep mixing method together with geogrid, by analyzing these two tests. This paper introduces the result of these tests and the result of a numerical analysis.

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As a background, we could see several damages occurred by the liquefaction on the earthquake of the West Tottori Pref on Oct. 6. 2000. However, in this situation, it was clear that areas geotextile method wasn't damaged so seriously.
So, we would explore two points: 1) the case study of situations on geotextile method using areas; 2) the procedure of geotextile method's effectiveness through the experiment to see intuitionaly from the view that the soil has granular nature.
Consequently, we could see that land constructions can obtain stabilities, compensating weak points of the soil that has less tensile resistances, by geotextile materials.

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The use of geogrid steep-slope reinforced earth walls constructed using steel wall-surface material in road embankment work, is spreading rapidly. In Japan, more than 1, 000 such works have been executed with the reinforcement material (geogrid) arranged in a zigzag pattern. No significant deformation has been caused by the use of the zigzag pattern. This pattern enables all wall-surface material to be connected to the main reinforcement material (geogrid). This allows rational design and execution by eliminating the need for wall-surface stabilization reinforcement. This report contains the following information: ·Explanation of the zigzag pattern·Introduction of a design and an execution case

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The use of Geogrid steep-slope reinforced earth walls constructed using steel wall-surface material in road embankment work is spreading rapidly. However, many aspects of the installation of a guard rail in work of this kind are still not clearly understood. This paper introduces the results of a field test on a full-size embankment performed as a first step in making these points clear.
The purpose of this experiment are as follows:
(1) To study the effects of the installation of a guard rail on a Geogrid steep-slope reinforced earth wall
(2) To study the effects of the installation of a guard rail on the Geogrid
Therefore, the following items were included in the experiment:
(1) Measurement of the displacement of the reinforced earth wall and of the change in the horizontal earth pressure of the embankment when a static load and a dynamic load are applied to the guard rail
(2) Measurement of the strain distribution of the reinforcing material when a static load is applied to the guard rail
(3) Measurement of the state of the reinforcing material, and guard rail damage when a static load and a dynamic load are applied to the guard rail

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In the coastal areas of the Sea of Japan, there are many places that have high risk of rock fall because these areas have steep topographic features and soft soils as well as severe weather conditions. The authors planned to use a reinforced earth wall using geosynthetics as a retaining method for falling stones, capable of countering these topographic conditions and the large energy of falling stones. This retaining wall method for falling stones is a technique to receive falling stones on the top of a reinforced soil wall, and the impact of falling stones are absorbed by banking materials and a geogrid. In the past, we conducted an experiment to vertically drop a weight of 50kN from the height of 20 meters, as well as basic research on the evaluation of impact absorbing performance of this method and the mechanism.
A demonstration test was carried out for the following purposes: (1) to confirm the construction adaptability of this method at an actual site, (2) to confirm the route and impact of a falling stone and the behavior of a retaining wall for falling stones, by dropping actual stones on a slope face.
This paper presents the performance test on impact buffering materials conducted as a preliminary test, the adaptability of actual construction work, and the results of falling stone demonstration experiment.

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The first prototype reinforced soil bridge pier was constructed by means of preloaded and prestressed (PLPS) reinforced soil method, which aims at substantially increasing the stiffness of a geosynthetic-reinforced soil embankment by vertical preloading and prestressing. After the usage for a period of three and half years, cyclic and creep loading tests in the vertical direction were performed on this pier before its destruction work. In this paper, the deformation characteristics of the PLPS structures are discussed based on behaviours of the pier during the construction, the service period, and the final loading tests.

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To evaluate the effects of preloading and prestressing on deformation characteristics by cyclic loading for a long term performance of reinforced soil structures, a series of cyclic and creep tests were performed on small models. No distinct difference was found in the increasing rate with time of residual strain between a cyclic loading test and a constant pressure creep test at a preloading state. The amount of residual strain by cyclic loading at an unloaded state (i. e., prestressed state) decreased by applying in advance long-term constant pressure or cyclic loading at the preloaded condition. Applying cyclic loading at the preloading state was slightly more effective. When swelling was allowed to take place at a prestress state. the deformation during the subsequent cyclic loading test became larger.

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Based on the hyperbolic load versus settlement relation, a method was proposed for predicting the settlement of foundations reinforced with combining geosynthetic and sand mat. The method was characterized by taking not only increase in bearing capacity but also increase in stiffness of foundations into consideration. The calculated results indicate that the reduction of settlements of foundations due to reinforcement with geosynthetics is given as a function of the initial safety factor without reinforcement, bearing capacity increment ratio and stiffness increment ratio.

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The potential benefits of geo-composites in reinforced foundation beds are investigated. Dry Toyoura sand at three different densities (Dr=32%, Dr=70%, Dr=89%) has been used for the investigation. Medium size model box along with loading frame are fabricated to carry out tests on a 10cm wide (B) strip footing. One geo-composite layer was used centrally below the footing at different depths and lengths. From the test results, optimum length (L) of reinforcement was found to vary between 2B to 3B and placement depth (U) was between 0.25B to 0.5B. Same trend has been observed for three different densities. Moreover, at medium density load and settlement response showed significant improvement.

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A simple and hand-calculable method has been proposed for estimating the undrained shear strength of reinforce/drainage geotextile (RD-G) reinforced clayey embankment. Comparing with FEM analysis results, it shows that the method slightly over-predicts the pore pressure in clayey backfill with an error of about 5% of the applied load. To predict the undrained shear strength, one of the important parameters is the transmissivity of RD-G (Q_w). Laboratory test rests revealed that Q_w reduced significantly with the increase of confining pressure and the elapsed time in the case of clay confinement. It is suggested that for design, long-term confined in-clay Q_w value under corresponding confining pressure should be used. Finally, the effects of construction speed and Q_w value on the undrained shear strength of clayey backfill were investigated by the proposed method. It has been demonstrated that the method is useful for design RD-G reinforced clayey embankment.

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The discharge capacity (q_w) of prefabricated horizontal drain (PHD) placed at the base of embankment on soft subsoil is investigated by laboratory tests. For two PHDs tested, although their q_w values reduced with confining pressure and elapsed time, for the conditions investigated, their long-term confined in clay q_w values were more than 16, 000m³/yr/m. The field performance of PHD has been investigated by FEM analysis. Under the assumed conditions, the analysis results indicate that when q_w>1, 000m³/yr/m, q_w value will have almost no effect on embankment settlement. This suggested that the two PHDs tested are suitable as drainage material under embankment on soft subsoil

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Geotextile, which is a sheet-like drainage or permeable material in both a normal direction to the plane and its cross-sectional direction, is often applied recently to the usage of the embankment constructed using a high moisture content cohesive soil including a poor surplus soil produced in a construction site or the backfilling material needed to be dewatered in cases of fully saturated condition. In this study a laboratory model test experiment is carried out to investigate a fundamental hydraulic behavior of soil-geotextile composite system and the effects of thickness of spunbonded geotextile, overburden pressure, different gradation of soil, degree of compaction (apparent density of soil on tansmissivity and permittivity of the complex system.

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When base of landfill subsides, deformation occurs in the geomenbrane which is used as a component of liner. Usually, geotextile is being used to protect a geomenbrane from mechanical damage. This geotextile seems to have function as reinforcing the geomenbrane when it deform. A geogrid if it was used together with the non-woven textile may emphasize this reinforcing. This effect was examined here by placing a geogrid together with the geotextiles over soft geomembrane (FPA). Consequently, the amount of the maximum tensile strain creating in geomenbrane reduced to about 50% of that of in case of without geogrid and geotextile.

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The authors conducted a puncture test using a nail with a diameter of 3.7mm, a top angle of 15 degrees and length of 65mm for geomembrans and geotextiles placed on the compacted model ground with various corn resistance (q_c).
The results obtained were compered with those obtained using a piston based on standard of ASTM D4833. Second, they also conducted a puncture tests using a nail for double-liner system. Last, they examined efficiency of estimating method proposed by O. Ariteres for our all results.

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New water proofing sheet for underground construction such as subways was developed. Special ethylene-vinyl acetate co-polymer was applied to this new sheet which shows excellent chemical adhesion to cement matrixes.
This sheet should be stuck to the base wall before constructing buildings. Even if underground water comes into the base wall, water leakage into the building scarcely occur because of the strong adhesion between the sheet and concrete wall of the building.

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Snow weight takes an important role in a cold area on maintaining its facility of a seepage control liner for a long period of time. However, there isn't enough data accumulated relating to the behavior of seepage control liner under snow condition and cold temperature. We had a chance to measure its behavior of a seepage control liner at the prototype test field. Its conditions are divided into two types of slopes. Each of which covered respectively by the two different structures of liners. The one of them consists of unwoven textile and seepage control liner, and the other consists of covering soil, unwoven textile and seepage control liner. The deformations of liners are targets to measure that caused by temperature under snow weight. In the same manner, the deformation of high dense polyethylene and the low dense produced by using metallocene catalyst was measured under the outside temperature. These results are shown in this paper.

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The installation of seepage control systems using liners made of impermeable materials has been used obligatory at final waste landfill. Sheets made of synthetic rubber and similar materials have conventionally been used for this purpose, but a problem has been presented recent years such as the leakage of contaminated water through perforations and defective joints of the sheets. In this study, the authors have reported the performance of self repairing geomembrane, which is developed as a cutoff material for waste landfill. They report in this paper, the self-repairing performance of this geomembrane, which has been exposed for 2 or 4 years and that of the newly developed geomembrane that is easier to construct than present geomembrane.

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The triple composite liner is one of structures of seepage control system, which intercepts water infiltrating into ground from a final waste landfill. It is the combination of sheet as a first liner, geo-synthetics clay liner supported by a high dense polyethylene, and compacted soil mixed with bentonite. This liner is to purify quality of seepage water by the absorption of a bentonite liner through infiltration process, and preserve ecological environment in well condition. This paper demonstrates the seepage control effect of the triple composite liner by the results of permeability test conducted at the joint of liners, and also shows results of the permeability test using the specimen of mixed soil with bentonite. Furthermore travel times calculated for some types of seepage control systems are compared to evaluate their functions.

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Leakage water from a final waste disposal site through geomembrane takes an important role on improvement of composite lining structures of the final waste disposal site. However, there are few evaluation methods at the present except of the equation proposed by Giroud & Bonaparte for effective designing. However, it is pointed out that this equation doesn't include thickness of layer as variable. Therefore, in this paper, four simplified equation are proposed and compared to evaluate their suitability to the results by FEM analysis. As the results of comparative study, the well fitting equation of them is selected to give a similar value with ones estimated by FEM analysis and Giroud & Bonaparte's equation. According to the selected simple equation, leakage volume of water is proportional to the hydraulic conductivity of composite lining and the diameter of holes punctuated in a geomenbrane. Furthermore, this equation proves that the thickness of composite lining takes a minor role on the barrier effect as Giroud & Bonaparte's equation already indicated.

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The factor of damage in geomembrane liner is in design, construction and maintenance. Recently finding of damage in geomembrane liner is easy the electrical leak detction systems.
But an inspection of continuity of seam of geomembrane under construcion is very diffcult.
This paper presents new method in inspection of geomembrane seams under consuruction.

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This paper describes development of a floating canopy system for farm ponds as a new application of geomembranes. At farm ponds without a roof, occurrence of waterbloom or deposition of garbage and fallen leaves cause troubles on the operation and maintenance. To improve these situations, additional construction demand of the roof for existing farm ponds has increased. These farm ponds, however, are not designed as the structure whose roof can be constructed. Therefore, the application of conventional roof construction methods poses the problems such as structure, bearing capacity and cost. To solve these problems, we developed a floating canopy system using geomembranes, which have two characteristics of flexibility and low specific gravity. This new system hardly applies new load to existing farm ponds. In addition, the system reduces the cost compared with the conventional roof model. In the development process, we executed the laboratory experiments of several types of floating canopy system, and selected the best structural type. Then we conducted field tests at a farm pond actually used to evaluate the usefulness of this system.

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The behavior of a Geosynthetic reinforced sand revetment (GRSR) is simulated using a “wave-maker tank”. The GRSR is built inside the “wave maker tank” and is subjected to different kinds of simulated traveling ocean waves. It consists of four-layers of wrap around geosynthetic filled by Toyoura sand. Two kinds of GRSR were analyzed, one reinforced with a geocomposite and the second with a non-woven geotextile. Loose and dense sand were used, lateral and vertical deformations as well as density changes due to wave action were measured. Results from these model tests regarding relations among wave action-deformation, time dependent patterns, influence of wave height, collapse mechanism as well as the influence of the foundation are presented in this paper.

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In recent years, river revetment improvement work designed to create river works for natural conservation has been implemented in various parts of the country, in response to growing public consciousness of environmental conservation and to the revision of the River Law. The block mat system, which can be used to restore a site's vegetation by creating an earth cover, is a suitable method for constructing revetments on quasi-natural rivers. The “Basic Guidelines for Disaster Restoration to Conserve Beautiful Mountains and Rivers” designates it as a quasi-natural river revetment restoration method that can be applied to rivers with a flow velocity of up to 4m/sec. When it is actually applied, the method should be studied based on verification of the flow stability of the revetment blocks. This report presents an example of its application to river works for natural conservation performed after verifying the flow stability using a “sliding-colony” model and a “peeling” model.

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Retaining wall constructed in severe cold region may happen to be suffered serious damages due to the ground freezing. This study aims to clarify the effect of adiabatic method. The adiabatic materials is adopted the rigid polyurethane foam which has the lowest heat conductivity, and set between wall and ground for heat insulation..
The object of this analysis is the reinforced retaining wall constructed at the site of New Shinkansen Line projects. This retaining wall is measured displacements of wall, temperatures in wall and ground and strains of reinforcement rod. Heat conduction analysis was performed about this retaining wall, in order to verify the heat constants and analysis method through the comparison between measured and computed temperatures. Hence, the effect of adiabatic method was clarified.

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Geogrids and expanded polystyrol (EPS) products have been recently employed for the construction of earth structures. In this paper, the mechanism of earth pressure reduction, acting on the wall retaining geogrid and EPS reinforced sandy soils, are explored using a large-scale model container with a mobile retaining model wall. It is found that the installation of EPS blocks behind the wall reduces the earth pressure at rest, and that the embedment of geogrid layers within the backfill reduces the active earth pressure. The mechanism behind the earth pressure reduction is discussed in connection with compressive displacement of EPS blocks, tensile strains developed along geogrid layers, and so forth.

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We proposed the simple equation in the past to predict the coefficient of vertical earth pressure acting on a box culvert with compressible material installed on its top. This material is aimed to install to reduce the earth pressure acting on the box culvert. Although the simple equation was derived under the simple hypothesis, it was proved to give a reasonable value. On this study, range of applicability and acceptability of this equation is targeted to investigate using data in public shown in the references and FEM analysis. Furthermore, this equation is extended out of limitation to predict earth pressure acting on pipe culvert through a flexibility factor as indicator representing deformability of pipe.

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