This paper summarizes the seismic response of five large-scale retaining walls having a geocell facing. The walls were 2.8 m high and the backfill and foundation soil were a fine sand compacted to 90% standard Proctor density (relative density of 55%). The first two walls were of the same geometry, with a tapered facing made of geocells each of height 20 cm, one infilled with gravel and the other with sand. In Wall 3, a facing of depth 60 cm was constructed while the backfill sand was reinforced with a polyester geogrid. Wall 4 was similar to Wall 3 except that the backfill was reinforced with several geocell layers. Wall 5 had thin geocell layers of 5 cm height as reinforcements in order to improve the performance compared with Wall 4. The walls were subjected to the scaled horizontal and vertical motions as recorded during the 1995 Kobe earthquake, 4.5 m/s² (450 gal) and 9.0 m/s² (900 gal) maximum horizontal accelerations in the first and second excitations, respectively. In an attempt to induce failure, and therefore, to investigate the failure mechanism, Walls 3 – 5 were subjected to a third shaking in which the horizontal accelerations were scaled to 12.0 m/s² (1,200 gal). The walls were fully instrumented with accelerometers, laser displacement transducers, force transducers, and strain gauges. All five walls performed satisfactorily under the simulated earthquake motions. An improved wall performance was seen with the geocells acting as reinforcement layers. The study showed that geocells can be used successfully to form gravity walls as well as reinforcement layers even when subjected to a very high seismic load beyond that of the Kobe earthquake.

Seismic response of geocell retaining walls: Experimental studies

Rigid pipes under high embankments are often installed using the induced trench technique by introducing a compressible zone above the pipe. Made from discarded tires, tire-derived aggregate (TDA) ...

https://www.icevirtuallibrary.com/doi/pdf/10.1680/jgein.18.00013

Numerical study of earth pressures on rigid pipes with tire-derived aggregate inclusions

The current design practice in the UK for estimating the soil pressure on a buried pipe under traffic loads is based on a simple equation derived using a Boussinesq solution. In order to test and verify this equation, and study the effect of pipe diameter and backfill height for rigid (concrete) and flexible (polyvinyl chloride (PVC)) pipes, a study has been conducted using three-dimensional finite-element modelling. It was found that increasing the diameter of the concrete pipe non-linearly decreases the maximum vertical displacement, while the relationship between the concrete pipe diameter and the maximum thrust force was found to be dependent on the backfill height. Increasing the diameter of the PVC pipe linearly increases the displacement and the maximum thrust force. The effect of traffic live load on the maximum thrust force becomes insignificant for a cover depth larger than 2 m and 3 m for the concrete and PVC pipes, respectively. The results indicate that there are significant issues with the m...

/pdf/the-response-of-buried-pipes-to-uk-standard-traffic-loading-47x81mtaoq.pdf

The response of buried pipes to UK standard traffic loading

Induced Trench Installation (ITI) is a viable option to reduce the load on rigid culverts buried under high embankments. However, reliable design methods are limited, which restricts further applications of this technology. Based on Marston's formula, a modified analytical solution is proposed, in which the vertical stress across the width of the soil column immediately above the compressible layer is assumed to be distributed in a parabolic shape, and the effects of the geometry and stiffness of the soft layer on load reduction are considered explicitly. Comprehensive comparisons are made between field monitored results and the calculations from different design methods. Parametric studies are subsequently conducted to investigate the influence of different distribution patterns of vertical stress and the properties of the soft layer. It is found that compared to Marston's theory, the proposed method yields a closer estimation to the field measured data. Finally, a simplified design chart is introduced, ...

Improved analytical solution of vertical pressure on top of induced trench rigid culverts

In this study the stress behavior of buried pipes in cohesionless soil was investigated experimentally. The parameters investigated in the laboratory tests include embedment ratio of pipe, horizontal distance of pipe to footing and the position of pipe. Hoop stresses at four positions on the borders of the pipes were measured by strain gauges. The results indicated that a significant increase in bearing capacities and decrease in pipe hoop stress when embedment ratio of pipe and horizontal distance of pipe to footing were increased. Based on the results of the laboratory model tests, the embedment ratio of pipe and the position of pipe are the main parameters that affect the hoop stresses on pipe.

Experimental Investigation of Soil — Structure — Pipe Interaction

The existing design guidelines for buried flexible pipes are limited to depth up to 10 m . The increasing use of difficult terrains for infrastructure, landfills, and residential and industrial developments has prompted installation of drainage pipelines under 20–30 m high fills. This paper presents the behavior of an instrumented flexible pipe buried under a 47.1 m deep fill. For filling above 20 m , the measured vertical stress above the pipe exhibited a concave distribution, corresponding to 90 and 110% of the average vertical pressure at the center and edges of the pipe, respectively. The measured results suggest that a triangular lateral pressure distribution can lead to overly conservative and uneconomical results for high fills while Spangler’s analysis is unconservative. Based on the measured results, a revised vertical and lateral earth pressure diagram was proposed for the design of flexible pipe under high fills >20 m . This paper proposes closed-form analyses for estimating the moments and dis...

Behavior of Buried Flexible Pipe under High Fills and Design Implications

Field buried pipe tests were conducted using steel pipes with 3500mm-diameter and 26mm-thickness as a part of Irrigation Pipeline Project. In current design for irrigation pipeline in Japan, there are no design criteria for pipeline with diameter larger than 3000 mm. In the field tests, two cases of backfilling methods were employed. In Case 1, soil-cement was used as backfill material to a height of half the diameter measured from the bottom of the pipe. In Case 2, soil-cement was used as backfill to a height of quarter diameter measured from the bottom of the pipe. The mixed rock, which was recycled crushed concrete and crushed gravel, was backfilled above soil-cement to the top of the pipe. The pipe was buried under a depth of approximately 3.0 m in both cases. Displacement transducers were installed in the pipes and strain gauges were attached to the inner of the pipe. Earth pressure transducers and pore water pressure transducers were installed in the backfill materials around the pipes. The deformations in each of the backfilling stage were measured. It is found that the behavior of the buried pipe was strongly influenced by backfilling methods and external force.

Field Test for Buried Large Steel Pipes with Thin Wall

This paper presents an overview of field tests for buried pipe, which were conducted using steel pipes with 3500 mm diameter and 26 mm thickness. In this full-scale test, five kinds of construction site were employed. The depth of soil cover was approximately 3.0 m in every case. Sheet pile method was employed in Case-5, and open-cut method was conducted in the other cases. Displacement transducers were installed in the pipe and strain gauges were circumferentially attached to the inner of the pipe. The deformation of pipe was observed for over a year by those measures. Therefore, it is found that the behavior of the buried pipe was strongly influenced by backfilling methods. In addition, FEM analyses were conducted to confirm the behavior of soil-pipe interaction. Thus, it is found that the inhomogeneous strength of backfill materials brings local deformation of the pipe.

Field Measurement and Numerical Analysis for Buried Large Diameter Steel Pipes

In recent years, many cases of secondary disasters have occurred owing to failures of irrigation ponds after large disasters such as the Great East Japan Earthquake, Northern Kyushu Heavy Rain, and the Heavy Rain Event of July 2018. At the National Agriculture and Food Research Organization (NARO), we have developed the Disaster Prevention Support System for Irrigation Ponds (hereinafter referred to as the DPSIP), which is aimed at sharing disaster information relating to irrigation ponds in times of major disaster. In this paper, we present the specifications of the DPSIP and the applicability of the system is also explained by applying the system to actual disasters and by conducting a verification test.

Development of Disaster Prevention Support System for Irrigation Pond (DPSIP)

The bearing mechanism of the timber pile has not been clarified in many ways. In this paper, vertical loading analysis of tapered timber piles is carried out by using two-dimensional distinct element method (DEM). It is considered that DEM is the most appropriate analysis method that simulates large displacement caused by pile driving. The parameters of DEM are determined by one dimensional consolidation test. The taper angle and the number of the driving pile are conditioned by taken into considerations practical situations. The displacement of ground particles and the contact force are investigated. Results show, that the bearing capacity of the tapered pile is developed as the taper angle increases. The tapered pile has significant effect on the horizontal contact force of the ground particles. The effect confining the surrounding ground is caused by the increase of the contact force due to the taper.

Daisuke Shoda

Papers

Behavior of Buried Flexible Pipe under High Fills and Design Implications

Field Test for Buried Large Steel Pipes with Thin Wall

Field Measurement and Numerical Analysis for Buried Large Diameter Steel Pipes

Development of Disaster Prevention Support System for Irrigation Pond (DPSIP)

Distinct Element Analysis For Group Piles Subjected to Vertical Loading