Showing papers on "Lateral earth pressure published in 1996"

Experimental study of rock sheds impacted by rock blocks

Abstract: Note: Roches Reference LMR-ARTICLE-1996-001 Record created on 2006-11-09, modified on 2016-08-08

Seismic-induced permanent displacement of geosynthetic-reinforced segmental retaining walls

Abstract: This paper describes the application of conventional displacement methods to estimate seismic-induced permanent displacements of geosynthetic-reinforced segmental retaining walls constructed on fir...

Ground response during diaphragm wall installation in clay: centrifuge model tests

Abstract: A series of centrifuge model tests has been carried out to investigate the ground movements which occur during the installation of diaphragm walls in clay soils. The paper describes the centrifuge modelling technique, with reference to features such as the high initial in situ lateral earth pressures in overconsolidated clay deposits, and the stress and drainage boundary conditions imposed at the interface between the trench and the soil. The changes in pore water pressure and ground movements observed during the simulation of slurry trenching and concreting in a number of centrifuge model tests are described, and the influence of groundwater level and trench geometry is discussed. Ground movements were found to depend on a number of factors, including the initial groundwater level and the geometry (length/depth ratio) of the panel. The initial groundwater level is particularly important: soil surface settlements were reduced by a factor of 10 when a plane strain excavation was carried out with the water-table 10 m below ground level rather than at the soil surface. For a diaphragm wall trench 18·5 m deep and 1 m wide, three-dimensional effects were found to reduce the displacements at the centre-line of a single panel by a factor of 3 (compared with the plane strain case) for a panel 5 m long, but the benefit for a panel 10 m long was much smaller.

Static and dynamic active earth pressure

Abstract: The dynamic active earth pressure on retaining structures due to seismic loading is commonly obtained by using the modified Coulomb's approach which is known as the Mononobe-Okabe method. This method has generally been used for cohesionless soils only. A general solution for the determination of total (i.e. static and dynamic) active earth force for a c-ϕ soil as backfill was developed by Prakash and Saran in 1966 based on the simplifying assumption that adhesion between the wall-soil interface is equal to the cohesion of the soil, that the surface of the backfill is horizontal, and that the effect of the vertical acceleration can be neglected. This note presents an improved method for calculating the static and dynamic active force behind a rigid retaining wall based on its geometry, inclination of the backfill, surcharge, strength parameters of the backfill, and the adhesion between the wall face and the soil. The effects of adhesion, inclination of backfill, and vertical components of seismic loading for a typical retaining wall are discussed.

Earth pressures due to compaction: comparison of theory with laboratory and field behavior

Abstract: Compaction of backfill adjacent to stiff and unyielding structures induces earth pressures in the compacted fill that exceed normal at-rest earth pressures. A numerical method that can be used to calculate compaction-induced lateral earth pressures has been proposed by Duncan and Seed. The purpose of the study described in this paper is to evaluate the theory by comparing calculated and measured compaction-induced lateral earth pressures. The data for the comparisons is from values measured in backfills behind three stiff, unyielding walls: the instrumented retaining wall in the Transport and Road Research Laboratory in Crawthorne, England; the instrumented retaining wall in the Virginia Tech Geotechnical Laboratory in Blacksburg, Virginia; and the lock walls at Eisenhower and Snell Locks in New York state. The lock walls were found to be cracked, apparently by high earth pressures induced by compaction, and an extensive rehabilitation program was required. The measurements from all three walls confirm th...

Difference between Load-Transfer Relationships for Laterally Loaded Pile Groups: Active p - y or Passive p -δ

Abstract: Two-dimensional (2D) finite-element analyses were carried out to study undrained soil deformation around piles displaced laterally through soil. The load-transfer p - curves produced were found to ...

Dynamic response of cantilever retaining walls

Abstract: A critical evaluation is made of the response to horizontal ground shaking of flexible cantilever retaining walls that are elastically constrained against rotation at their base. The retained medium is idealized as a uniform, linear, viscoelastic stratum of constant thickness and semi-infinite extent in the horizontal direction. The parameters varied include the flexibilities of the wall and its base, the properties of the retained medium, and the characteristics of the ground motion. In addition to long-period, effectively static excitations, both harmonic base motions and an actual earthquake record are considered. The response quantities examined include the displacements of the wall relative to the moving base, the wall pressures, and the associated shears and bending moments. The method of analysis employed is described only briefly, emphasis being placed on the presentation and interpretation of the comprehensive numerical solutions. It is shown that, for realistic wall flexibilities, the maximum wall forces are significantly lower than those obtained for fixed-based rigid walls and potentially of the same order of magnitude as those computed by the Mononobe-Okabe method.

Comparison of the pseudo-static and dynamic behaviour of gravity retaining walls

Abstract: Pseudo-static and dynamic non-linear finite element analyses have been performed to assess the dynamic behaviour of gravity retaining walls subjected to horizontal earthquake loading. In the pseudo-static analysis, the peak ground acceleration is converted into a pseudo-static inertia force and applied as a horizontal incremental gravity load. In the dynamic analysis, an actual measured earthquake acceleration time history has been scaled to provide peak ground acceleration values of 0.1 g and 0.3 g. Good agreement is obtained between the pseudo-static analysis and analytical methods for the calculation of the active coefficient of earth pressure. However, the results from the dynamic analysis require careful interpretation. In the pseudo-static analysis, the increase in the point of application of the resultant active force with the horizontal earthquake coefficient k h from the one-third point to the mid-height of the wall is clearly observed. In the dynamic analysis, the variation in the point of application is shown to be a function of the type of wall deformation. Both finite element analyses indicate the importance of determining the magnitude of the predicted displacements when assessing the behaviour of the wall to seismic loading.

Red River U-Frame Lock No. 1 Backfill-Structure-Foundation Interaction

Abstract: Using the backfill placement method of analysis, the authors were able to use a limited amount of data on soil properties and limited instrumentation readings to estimate lock performance from initial construction through major flood events, including siltation. Results of the complete soil-structure-foundation interaction analyses for four operational load cases were critical in interpreting instrumentation measurements. A distinction was made between soil-structure interaction of the compacted sand backfill and the stem walls and the interaction of the compacted sand backfill and the culvert walls. This investigation considered the characterization of the range in magnitudes and distributions of horizontal earth pressure coefficient, Kh, and vertical earth pressure coefficient, Kv, along the stem and culvert walls for each load case. Expressing the effective normal pressure and vertical shear stress along lock walls, in relation to earth pressure coefficients, allowed for the precise recovery of both normal and shear stresses for use in simplified design tools.

Soil Pressure Drop of Screw Conveyor for Shield Machines.

Abstract: Screw conveyors are generally used as excavated soil dischargers for earth pressure and muddy earth pressure types of shield machines. The conveyor discharges the soil continuously under loosened earth pressure and underground water pressure held by soil plugs which are formed in the screw grooves and the sand plug zone. In order to clarify the pressure-holding mechanism of the conveyor filled with the soil, the theoretical equations for granular and plasticized materials which represent the pressure drop in the screw conveyor were formulated. As the result of the investigations, the calculated values were found to be in good agreement with the experimental and practical Ones.

Analysis and Design of Retaining Structures Against Earthquakes

Abstract: This proceedings, \IAnalysis and Design of Retaining Structures Against Earthquakes\N, contains both invited and contributed papers, which focus on the questions of 1) dynamic earth pressures on fixed and movable rigid and flexible walls; 2) displacements in translation and rotation of walls under earthquakes; 3) behavior of fills and abutments during earthquake; and 4) centrifuge tests on walls. Both analytical and experimental data have been presented on possible behavior of retaining structures under seismic loading. A study of this volume and other published literature shows considerable effort is being devoted to determination of realistic dynamic pressures, displacement in translation and rotation of retaining structures and behavior of fills for abutments. Since a synthesis of these studies is not currently available, there are no unified and generally acceptable solutions to the above questions. However, the discussions and presentations of the papers during the session does highlight the need for such solutions and more definite descriptions of unsolved problems.

Instrumentation for determination of guardrail-soil interaction

Abstract: A series of steel posts (W150 X 12.6) and timber posts (15.2 X 20.3 cm) were instrumented with soil pressure transducers to assess the soil-post load response to a 1,388-kg bogie striking the post at 33 km/hr. Soil pressure measurements demonstrated the dramatic effects of soil shear strength and modulus on the responses of both timber and wood posts. The differences in the failure mechanisms between stiff and soft cohesive soils and noncohesive soils are demonstrated by both stress distributions and total stresses measured by the pressure transducers. The measurement system has potential applications for measurement of loads during impact testing of guardrail systems and as a tool for developing more appropriate models of soil behavior during impact loading.

Application of eps to backfill of abutment for earth pressure reduction and impact absorption

Abstract: In order to reduce static earth pressure acting behind the abutment during and after the construction of the backfill and the dynamic earth pressure due to earthquakes and traffic loads after the construction, an innovative method is proposed, which uses EPS as a cushion between the abutment and the treated backfill. It is shown that the construction cost is significantly saved by use of this method. For the covering abstract see ITRD E109968.

Soil Pressure Drops of Various Screw Conveyor Structures for Shield Machines.

Abstract: Pressure drop of the screw conveyors filled with plasticized soil for earth pressure shield machines can be calculated by the method described in the previous paper. In this paper, equations of the pressure drop for the shaftless coil screw called the ribbon screw and various conveyor structures have been formulated. On comparison of the calculated pressure drop, the screw with rotary casing showed the larger pressure drop, which is about twice that of a conventional type of conveyor.

Anchor with earth pressure plate

Abstract: PURPOSE: To make easy driving as an anchor fitted with an earth pressure plate by driving an anchor body fitted with a timbering arm into a slope, and coupling the front of the timbering arm upon the central part of an earth pressure receiving plate. CONSTITUTION: On a surrounded ground having got rid of surface brittle soil, for example in the form of a slope S, an earth pressure receiving plate 7 is set in the left-right orientation while its wide 7a is arranged horizontally, and an anchor body 1 fitted with a timbering arm is driven while an arm protrusion L is reserved, and the coupling part 5a in front of the timbering arm 5 is placed on the coupling part 7b of the earth pressure receiving plate 7 and coupled fast by a bolt and washer and driving is made with the over-part of the plate 7 as a back-fill anchor. The foremost part of a suspension rope, etc., is coupled appropriately from the central part of the plate 7 to the upper part 1a of the anchor body 1, and a protection fence, etc., is supported. The plate 7 is supported on the hard ground for a flexural deformation of the upper part 1a of the anchor body 1 caused by a load and a strong earth pressure reactive force F3 is produced, and the flexural deformation is prevented effectively.

Earth pressure reduction for culverts using eps

Abstract: As settlement differences between fills on top of culverts and those of surrounding culverts sometimes occur, box culverts today are designed anticipating earth pressure larger than the overburden pressure on culverts. Therefore, construction costs are higher because larger members for culverts are used. Although extra earth pressure is taken into account, earth pressure larger than this estimated amount is sometimes observed. A new construction method was examined, which reduces earth pressure acting on a culvert by placing a thin layer of EPS (Expanded Poly-Styrol) above a culvert and avoids the settlement difference. First, a model test and an FEM analysis were made before the trial construction. The results of the test and the FEM analysis show that earth pressure acting on the culvert in the section where the EPS was placed was about half of that in the section where no EPS was placed. Furthermore, from the results of the test and the FEM analysis, a trial construction and centrifuge model tests were made to confirm the effectiveness and to consider possible design methods. For the covering abstract see ITRD E109968.

Case histories of earth pressure-induced cracking of locks

Abstract: : The US Army Corps of Engineers is responsible for designing and maintaining a large number of navigation and flood-control structures. Massive unreinforced concrete gravity walls serve many uses at many of these hydraulic structures. These concrete gravity structures are used as lock walls, are typically founded on rock, and are subjected to large differential water and earth loadings. These structures must maintain their internal structural integrity and be stable with respect to sliding and overturning. However, some rock-founded, unreinforced, concrete gravity lock walls have experienced cracking as a result of earth loadings in excess of those anticipated during structural design. This report summarizes the existing information on four locks which have experienced cracking within the unreinforced lock walls. A fifth lock which was remediated to avoid cracking is also discussed. All five lock walls retain backfill. Backfill loads were found to be the primary type of loading on the walls.

Retaining wall and assembling method thereof

Abstract: PURPOSE:To dislocation and overturn of a retaining wall through reduction of earth pressure and to use the inside effectively by forming a curve curved in the rear, on the retaining wall, and making an angle between a lower part of the curve and a ground surface almost equal to the inclination of a sliding surface. CONSTITUTION:Plural pieces of a column made up of H-steel, steel structure, reinforced concrete, plastics or the like are erected on a base part 108 in both directions. In addition, concrete placing at a construction site is carried out in each interval between those of columns and/or plural pieces of panels such as prestressed concrete slabs and suchlike are held between in the vertical direction and joined together with a bonding member, whereby a retaining wall 100 with a curve 146 consisting of a perpendicular part 102 and both upper and lower parts 104 and 106 curved in the rear is constructed. Then an angle between the lower part 106 of the curve 146 and a ground surface 300 is made almost equal to the inclination psi of a sliding surface, and in an area A at an angle of below this inclination psi, earth pressure comes to zero, and this earth pressure is made so as to be imposed on only an area B of + or -200, whereby the earth pressure as a whole is made so as to be reduced. In this connection, a trough, a bench 147, flower bed 148, a footway 149, a drainage ditch 150, or the like may be installed on the inside of the curve 146.

Continuous underground wall construction process

Abstract: PURPOSE: To increase resistance force against the earth pressure from the side opposite tp any open space by excavating the soil of an existing ground, mixing the excavated soil with a solidifying material-slurry, thereby constructing a continuous underground wall CONSTITUTION: A bucket 2 is inserted into an excavated groove W, a solidifying material-slurry is poured into the soil, and the soil and the solidifying material-slurry are mixed-agitated by an agitating device 4 A flexible type arm 12 or the like is operated to move the bucket 2 up and down, and back and forth to construct a continuous underground wall Z1 made up of improved soil Then, on the upper part of the opposite side of the side where an open space will be formed later by excavation and soil removal, a swelling-body Z2 similarly-made up of improved soil is formed integrally with the continuous underground wall, and thus the center G of gravity of the whole of the continuous underground wall Z is off-centered to the side where the swelling-body is formed After the continuous underground wall Z with the swelling- body Z2 are solidified, the soil on the opposite side of the side where the swelling-body is formed, is excavated and removed to form an open space S there Thus, the soil of an existing ground is excavated by single excavator, and the excavated soil and a solidifying material-slurry are mixed to improve the soil of the part where a continuous underground wall is constructed

Bridge-Column Footings: An Improved Design Procedure

Abstract: The aim of this paper is to discuss and improve on the current highway bridge-footing design procedure. Five California highway-bridge-column footings are presented here as examples, and are analyzed by using both the current Caltrans design procedure and the proposed method, considering moments induced by lateral forces and footing depth. Considerations of passive soil pressure on the side of footings are also discussed in these case studies. The current Caltrans design procedure of neglecting moments induced by lateral forces and footings depth underestimates the soil/pile bearing reactions by about 16–78% for compression, about 27–47% for tension, about 27–75% for flexure bending moment for designing bottom reinforcement, and about 26–68% flexure bending moment for designing bottom reinforcement. The larger the footing depth and/or the shorter the column, the more unconservative the current design procedure.

Retaining wall structure

Abstract: PURPOSE:To protect a ground structure enough from earth pressure by providing a buttress-type retaining wall on the inner face of a recess being made by excavating the ground, and fixing the batholith with a permanent anchor driven vertically. CONSTITUTION:The ground is excavated vertically, and the flank of the excavation is timbered with shotcrete, a lock bolt, a ground anchor, etc., thus a recess 1 is made. Next, a buttress-type retaining wall 2 is provided at the inner flank 1a of the recess 1, and besides the batholith 2a of the retaining wall 2 is fixed by a permanent ground anchor 6 being driven vertically to the ground. And, an underground structure 7 being structurally cut off the retaining wall 2 is built in the recess 1. Therefore, the earth pressure from the ground is received enough by the retaining wall 2, and the underground structure 7 surrounded by the retaining wall 2 is protected from external force such as earth pressure, etc. Accordingly, the problem in strength of the underground structure 7 is solved, and the safety is secured.