Showing papers on "Lateral earth pressure published in 1991"

Finite cavity expansion in dilatant soils: loading analysis

Abstract: An analysis of the quasi-static expansion of a cylindrical or spherical cavity in an infinite dilatant elastic-plastic soil is presented Closed form solutions for the stress and displacement fields in the soil during the expansion of the cavity are given The soil is modelled as linear elastic-perfectly plastic, using a non-associated Mohr-Coulomb yield criterion An explicit solution for the pressure-expansion relationship is obtained with no restriction on the magnitude of the deformation It is found, in particular, that the radius of the cavity increases indefinitely as the cavity pressure approaches a finite limiting value This limiting pressure can be determined analytically with the help of a single expansion of an infinite series The novelty of the new solution lies in the introduction of dilation to the analysis of large strain expansion Examples of the implications of the new analysis in geotechnical engineering are discussed L'article presente une analyse de l'expansion quasistatique d'une

Load transfer for pipe piles in highly pressured dense sand

Abstract: Large-scale loading tests were conducted on closed-toe and open-toe piles driven into dense submerged sand confined in a pressure chamber. Unit load-transfer relations were developed and related to stress conditions in the chamber. Ultimate shaft resistance in compressional loading was found to be approximately equal to the ambient lateral effective stress in the chamber before driving, and was generally not dependent on the geometry of the toe. From this observation it can be inferred that because of installation and loading effects the operative earth-pressure coefficient on the pile shaft approximately doubled from the ambient value that existed before driving. In uplift, ultimate shaft resistance was about 20% lower than in compression, regardless of depth. The open-toe piles consistently remained plugged during static testing but nonetheless exhibited lower bearing capacity than the closed-toe piles. This can be explained by deformation and compression of the soil within the plug as a means of effectively reducing the rigidity index of the soil against which the toe bears.

Estimation earth pressures due to compaction

Abstract: When soil is compacted in layers by rollers, vibrating plates, or rammers, the horizontal earth pressures within the compacted soil mass are increased. Charts are presented that can be used to estimate compaction‐induced earth pressures quickly and reliably. These charts are developed using the hysteretic theory developed by Duncan and Seed, with a computer program called EPCOMP2. The charts offer the advantages of being easy to use, and providing very rapid results, while retaining most of the accuracy of the detailed computer analyses. Because earth pressures can be estimated quickly, it is easy to evaluate the effects of changes in the factors that influence the magnitudes of the compaction‐induced earth pressures. Comparisons of earth pressures calculated using these charts with the results of computer analyses indicate that the values calculated using the charts are sufficiently accurate for practical purposes. Field measurements of compaction‐induced earth pressures indicate that the horizontal eart...

Finite element analyses of an in situ wall propped at formation level

Abstract: The use of formation-level props to support an in situ retaining wall can result in a structural system which is stiff and remote from rotational failure. However, the interaction between the wail, the soil and a continuous prop slab cannot be analysed using simple techniques. Finite element analyses have been carried out to investigate some of the factors affecting the behaviour of an in situ wall, propped at formation level, retaining 9 m of stiff overconsolidated boulder clay. This Paper describes the results of a parametric study in which the effects of soil/wall/prop stiffness and the pre-excavation earth pressure coefficient were investigated. It is found that, because the wall is very stiff, computed deformations are governed by the assumed stiffness of the soil rather than the flexura! rigidity of the wall. Bending moments in the wall are influenced significantly by the assumed pre-excavation lateral earth pressures and, to a lesser extent, by the nature of the structural connection between the wa...

Ground anchors and soil nails in retaining structures

Abstract: Ground anchor and soil nail retaining systems are designed to stabilize and support natural and engineered structures and to restrain their movement using tension-resisting elements. The basic design concept consists of transferring the resisting tensile forces generated in the inclusions into the ground through the friction (or adhesion) mobilized at the interfaces. These systems allow the engineer to efficiently use the in-situ ground in providing vertical or lateral structural support. They present significant technical advantages over conventional rigid gravity retaining walls or external bracing systems that result in substantial cost savings and reduced construction period. Therefore, during the past few decades, ground anchors, and more recently soil nails, have been increasingly used in civil engineering projects.

The pressure of clay backfill against retaining structures

Abstract: This paper investigates the pressures exerted by clay backfills against retaining structures. The lateral pressures are developed during three main phases: placement, compaction, and burial; horizo...

Model pile testing in carbonate sediments of the Red Sea

Abstract: This paper presents the results of an experimental program of model piles in carbonate soil from the Red Sea. Direct and triaxial shear tests of the soil indicated very high effective angles of friction. These angles were greatly affected by confining pressures and relative densities. Results of model pile tests with and without applied surcharge pressures showed early peak frictional resistances for different relative densities. The peaks were stronger in the former case and followed by strain softening down to "stable" residual values. These residual values were found to be comparable with limiting values of friction predicted on the basis of limiting compressibility indices. Also, it was noticed that at the beginning of penetration, most of the applied load was taken by end bearing, but frictional share increased with further penetration until it took more than 50% of the load. Calculated values of the lateral soil pressure coefficient, Ks, showed a continuous decrease with penetration and it stabilize...

Retaining Structures and Excavations

Abstract: Structures that retain lateral forces from soil and/or water are composed of various materials, constructed by numerous procedures and methods, and are used for many purposes. In this chapter the manner of support is used to classify the different types of structures. Reinforced earth structures are not included, as that type of structure is covered in Chapter 21. The three means of support consist of restrained, gravity, and cantilever systems. Each support system has variations—the restrained system having the greatest number and cantilever the least. Gravity structures are far more numerous than the other two since they are used for the construction of many small structures such as soil-retaining walls. The largest retaining structures are of the gravity type. Restrained structures are prominent in the construction of waterfront facilities and excavations. Cantilever structures are the least used because they allow large deflections to occur. Combinations of support types are sometimes used.

Analysis of large diameter high-density polyethylene plastic pipes as vertical shafts in landfills

Abstract: The recent trend in the increasing use of large diameter flexible plastic pipes as vertical shafts or manholes in landfills or hazardous waste containment areas has resulted in a need for a thorough understanding of the soil-structure interaction of these pipes for the purpose of design. In this paper the soil-structure interaction response of flexible vertical shafts in landfills is described. A plane strain finite element program is modified and converted into an axisymmetric finite element program which then is used to determine the displacements and stresses in the pipe and the surrounding fill. The analysis is comprehensive, considering the effects of incremental construction, compaction, and creep of the pipe and the fill material. The calculated responses of the finite element analysis are illustrated in a number of graphs which demonstrate how the lateral earth pressure, hoop stress and strain, vertical stress and strain, and vertical thrust in the pipe wall vary with the design variables. The variables are the pipe diameter and thickness, compaction level, duration of construction time, and fill depth. It is found that as the height of the pipe and fill increase, a stronger schedule of pipe needs to be used to prevent buckling. The hoop strain at the bottom of the pipe is the critical design element, since it is the only pipe response that increases with the soil and pipe creep.

Soil cement self-supporting landslide protection wall and execution method thereof

Abstract: PURPOSE:To strengthen resistance force against bending moment by placing reinforced cores respectively to the tensile side and compressed side influenced by earth pressure in a soil cement column, and reinforcing with lateral ties to execute. CONSTITUTION:Reinforced cores 2 and 3 are placed in the direction of the axial center across the center line L to each position of the tensile side and compressed side influenced by earth pressure in a soil cement column 1, and the ends of the lower ends 2a and 3a of the cores 2 and 3 are bent upward. Parts of the reinforced cores 2 and 3 correspondent approximately to the excavated surface E are wound with lateral ties as reinforced bars at a narrow pitch to reinforce, and a reinforced cage 6 is formed. After that, when the reinforced cage 6 is erected, the reinforced cage 6 is erected by a steel framed erection jig 7 provided in advance, and after that, the jig 7 is only drawn out of the column 1 to facilitate execution.

Horizontal earth pressures on box culverts, abutments and walls due to wheel loads

Abstract: This paper presents a more fundamental understanding of the nature of live load induced horizontal earth pressure and its interaction with earth pressures caused by fill and compaction. 'Live load surcharge' horizontal earth pressure is shown to be the cumulative and residual resultant of priors loading history, including loading during construction. Consequently, live load induced horizontal earth pressure can exist without concurrent loading by traffic wheel loads. This is in marked contrast to the traditional treatment of live loads in structural design codes. This new concept has considerable implications for the design and construction of box culverts, abutments, and retaining walls. Design expressions are given for the horizontal pressure due to the AUSTROADS T44 Truck Loading and the Heavy Load Platforms.

Reduction method of earth pressure against structure

Abstract: PURPOSE:To stabilize a back-filling section by forming a boundary plane between the back-filling section and back-sand into such a plane that combines an inclined angle generating no earth pressure from sand with an inclined angle capable of transmitting the earth pressure from the sand to the bottom of the back-filling section. CONSTITUTION:A back-filling section 2 of a structure 1 such as a retaining wall or an abutment or an underground construction, a steel sheet pile wall, etc. has independent efficiency, and the whole back-filling section 2 is combined to form. A boundary plane between the upper part of the back-filling section 2 and back-sand 3 is formed of a stabilized inclination A by properties of the back-sand 3. In addition, the boundary plane between the lower part of the back-filling section 2 and back-sand 3 is formed of an inclination B capable of transmitting earth pressure resultant force P from the sand 3 to the bottom of the back-filling section 2.

Developments in geotechnical aspects of embankments, excavations and buried structures

Abstract: Symposium on underground excavations in soils and rocks, including earth pressure theories, buried structures and tunnels / Bangkok / 1989 and Symposium on developments in laboratory and field tests in geotechnical engineering practice / Bangkok / 1990.

A method to estimate the normal dynamic earth pressure acting horizontally on side walls of underground conduit

Abstract: 地中ダクトの横断面方向の地震時動土圧をダクトの見掛けのせん断剛性率と土のせん断剛性率との比βを多数変えた数値実験により検討し, ダクト上下面位置の地盤せん断力TUとTLをダクトがTUとαTLだけ負担し不均衡量が土圧に転ずること, 負担率がα=α0+α1logβで表せること, 主要動土圧はせん断力によるダクト変位と自由地盤の変位との相対変位に比例すること等を解明し動土圧の定量的評価法を提案した.

Construction of block retaining wall and retaining wall block

Abstract: PURPOSE:To construct a stabilized retaining wall having excellent earth pressure yielding strength by arranging precast blocks having bearing stays extending to the rears of sheathing plates so as to stride over reinforcements provided on the foundation ground to fill hardening materials into a lower space. CONSTITUTION:A retaining wall block A standing by itself at two points of the lower end 11 of sheathing plates 1 of the retaining wall block forming a retaining wall surface on the surface thereof and having injection holes 21 by projecting bearing stays 2 to the rear and a stay tail end 22 is precasted. After that, a site subject to construction is readjusted to construct a foundation line G, and reinforcements M are arranged so as to stride over the inside of a space section 3 to stand the retaining wall blocks A in a line. The blocks are coupled with each other, the legs are solidified with concrete, and concrete P, etc., are poured into the space section 3 from the injection holes 21 to harden. According to the constitution, yielding strength against earth pressure from a banking side is strengthened rationally, and a break-down or fall-down of the retaining wall can be surely prevented.

An experimental study on dynamic earth pressure acting on side walls of underground conduit

Abstract: ダブルボックスラーメンの地中ダクトの横断面方向の地震時動土圧を模型振動実験と数値実験により検討し, ダクトの見掛けのせん断剛性率と土のせん断剛性率の大小関係に応じて基盤入力の同一位相における側壁水平動土圧の作用方向が逆転すること, 原因は地盤から伝達されるせん断力と上記剛性比に応じてダクトが負担する力の不均衝量が土圧に転ずるためであること等, 地震時動土圧発生機構を定性的に解明した.

An estimation method of shear resistance force and earth pressure of fill materials in the steel made sabo structure

Abstract: 本研究は, 鋼製枠砂防構造物の礫中詰材のせん断抵抗力および中詰材圧を推定する手法について研究したものである. すなわち, 矩形の単純せん断枠および階段型の単純せん断枠の中に数種類の礫中詰材を詰めて, そのせん断抵抗力-変位関係を実験的に求めた. つづいて, 実験式および側壁面に生ずる中詰材圧の分布形状モデルを提案し, これを用いて中詰材のせん断抵抗力-変位関係および中詰材圧を推定する手法を示した.

Laying method for underground buried pipe

Abstract: PURPOSE:To prevent the reduction of the horizontal soil pressure applied on a pipe side surface by laying frictional sheets in the vertical direction into the refilling soil and sand used to the intermediate position between a pipe top and a ground surface from the position directly under the pipe, in the pipe laying method in which a pipe is arranged in an excavation groove and refilling is carried out by soil and sand, then and a sheet pile is pulled out. CONSTITUTION:Sheet piles 3 are driven on both the sides of an excavation groove to do the sheathing, while a frictional sheet (b) is placed to arrange a pipe 6 is arranged. The excavation groove 2 is refilled with soil and sand (a). Refilling is carried out to the intermediate position P2 between a pipe top P1 and a ground surface 1 from the position directly under the pipe 6, and a plurality of frictional sheets (b) are laid into the soil and sand (a), keeping each interval in the vertical direction. Then, the sheet pile 3 is pulled out, and a refilling surface 50 is rolling-pressed by a rammer, etc., and the pipe 6 is laid. Accordingly, the horizontal soil pressure which acts on the pipe side surface can be kept sufficiently constant without reducing the soil pressure, and the imbalance accompanied with the pulling-out of the sheet pile between the vertical soil pressure and the horizontal soil pressure can be avoided.

Computer aided design of geosynthetic reinforced soil walls

Abstract: The computer aided design of geosynthetic reinforced soil walls is reported. The magnitude of tensile forces in the geosynthetic reinforcement has also been studied under external vertical and horizontal strip loads.

Double cone pressure meter

Abstract: A double cone pressuremeter has a body (1) in the shape of two hollow cones placed base to base. As the device is pushed downwards into the ground, the solid nature of the variable diameter fixed body (1) forces the surrounding soil at a particular level to deflect radially outwards and then inwards in a controlled manner and at a predetermined rate in order to force upon the soil the type of deformation required to carry out a pressuremeter test. Strain gauged circular hoops (10) set flush with the outer surface of the device measure the soil pressure. Drilling fluid passes down a pipe (5) and is removed together with soil or rock waste via the annulus between the pipe (5) and body (1). Water pressure is measured by sensors (11).