Showing papers on "Lateral earth pressure published in 1992"

Principles of Soil Dynamics

Abstract: Fundamentals of vibration Waves in elastic medium Properties of dynamically loaded soils Foundation vibration Dynamic bearing capacity of shallow foundations Earthquake and ground vibration Lateral earth pressure on retaining walls Compressibility of soils under dynamic loads Liquefaction of soil Machine foundation on piles Seismic stability of earth embankments.

The Seismic Design of Waterfront Retaining Structures

Abstract: : This technical report deals with the soil mechanics aspects of the design of waterfront retaining structures built to withstand the effects of earthquake loadings. It addresses the stability and movement of gravity retaining walls and anchored sheet pile walls, and the dynamic forces against the walls of drydocks and U-frame locks. The effects of wall displacements, submergence, liquefaction potential, and excess pore water pressures, as well as inertial and hydrodynamic forces, are incorporated in the design procedures. Several new computational procedures are described in this report. The procedures used to calculate the dynamic earth pressures acting on retaining structures consider the magnitude of wall displacements. For example, dynamic active earth pressures are computed for walls that retain yielding backfills, i. e., backfills that undergo sufficient displacements during seismic event to mobilize fully the shear resistance of the boil. For smaller wall movements, the shear resistance of the soil is not fully mobilized and the dynamic earth pressures acting on those walls are greater because the soil comprising the backfill does not yield, i.e., a nonyielding backfill. Procedures for incorporating the effects of submergence within the earth pressure computations, including consideration of excess pore water pressures, are described.... Dynamic earth pressures, Hydraulic structures, Earthquake engineering, Soil dynamics, Earth retaining structures.

Soil mechanics. 5th edition

Abstract: This book, which is intended to serve the needs of the undergraduate civil engineering student, provides information on the following aspects of soil mechanics: basic characterisitcs of soils; seepage; effective stress; shear strength; stresses and displacements; lateral earth pressure; consolidation theory; bearing capacity; stability of slopes; and ground investigation. Worked examples are included throughout the book.

Seismic passive resistance of tied-back walls

Abstract: Previous work on the seismic behavior of retaining walls is briefly reviewed, and in particular, the Mononobe‐Okabe analysis for the limiting passive resistance is discussed. A test series is described that considers passive failure of a wall rotating about an 'anchor' at the top. Passive failure is induced by subjecting a small test wall to a roughly constant horizontal force, then shaking it with discrete pulses. Development of failure surfaces is observed, and forces, displacements, and acceleration distributions are recorded for each pulse. It is concluded that use of the sliding‐block model based on the Mononobe‐Okabe passive equations is justified for analysis and design, but that in practice, because of the large toe forces involved, migration of the active and passive resultants and reduced anchor resistance, a tied‐back wall would be more likely to suffer an anchorage failure with translation and rotation about the bottom than with rotation about the top.

Retaining Wall With Reinforced Cohesionless Backfill

Abstract: The case of a rigid wall retaining a reinforced cohesionless fill that carries a uniform surcharge load has been analyzed based on the limit equilibrium approach The reinforcement may be in the form of strips or mats that are not connected to the wall This analysis considers the stability of an element of the failure wedge, which is assumed to develop in the reinforced earth mass adjoining the back face of the wall Nondimensional design charts have been developed for computing the resulting lateral earth pressure on the wall and the height of its point of application above the base of the wall The theoretical findings have been verified in two different sets of model tests on a rigid wall that is retaining a dry sand fill and that is reinforced by aluminium and bamboo strips Experimental results are in good agreement with the theoretical predictions An applied example for an 8-m high wall illustrates the design procedure

Effects of K0 and Overconsolidation on Uplift Capacity

Abstract: This paper presents the results of experimental and theoretical studies on the determination of the overconsolidation ratio and its effect on the uplift capacity of foundations, with special reference to screw anchors installed in sand. Based on data reported in the literature, a semi-empirical relationship is proposed to relate the uplift capacity of anchors installed in overconsolidated sand to those installed in normal consolidated sand. Good agreement was observed when present experimental results were compared with the results of a theory reported in the literature after incorporating the effect of the overconsolidation.

Balanced Seismic Design of Anchored Retaining Walls

Abstract: Large permanent displacements of anchored retaining walls such as quay walls, sheet-pile walls, and bulkheads are often reported in the literature after moderate to strong seismic activity. In most cases, liquefaction of the soil is cited as the reason for the large displacements or failures. In this paper, we examine an alternative mechanism, generated by inertial forces, which triggers large displacements of anchored retaining walls during moderate to strong earthquakes. Through this mechanism, we investigate whether substantial wall displacements or failures precede liquefaction. A limit equilibrium analysis, using the Mononobe-Okabe seismic earth pressure equations, is performed to determine whether anchor failures lead to the general failure of anchored retaining walls during seismic events. Results of shaking-table tests on aluminum walls with a dry cohesionless soil as the backfill confirm the analytical methodology. Based on the limit analysis, a balanced seismic design concept for anchored retaining walls is presented. We find that the balanced seismic design enhances the seismic resistance of anchored retaining walls at little additional expense. We use a typical design example to compare the balanced design procedure with current design practices.

Stability of unsupported tunnels in clay

Abstract: An overall long-term stability of unsupported shallow tunnels in overconsolidated clays which is directly related to the stand-up time is investigated. A new approach that combines finite element methods and the limit equilibrium theory is used to overcome limitations of current design practice. A more realistic initial stress field, unloading due to excavation, and variation of strength and modulus with depth are used. The pore-pressure change is analysed using a finite element model that incorporates an uncoupled consolidation theory. These pore pressures along with the previously obtained stress field are utilized to predict the variation of stability with time for given soil parameters such as strength and coefficient of earth pressure at rest. The results obtained employing a simple mechanism are presented using non-dimensional quantities. These results relate time, stability of the tunnel, and soil strength. The analysis showed that, under certain circumstances, the initial undrained stability may b...

Pore pressures around tunnels in clay

Abstract: The pore-pressure generation and dissipation around shallow tunnels excavated in both normally and overconsolidated clays are investigated. The influence of the diameter D, depth of cover to diameter ratio H/D, coefficient of earth pressure at rest K0, and strength and modulus variations with depth on pore-pressure generation are examined. The effects of immediate support on pore pressure are also studied by defining a quantity termed effective stiffness ratio (ESR). A two-dimensional, nonlinear finite element analysis is performed to obtain the pore-pressure generation behav-iour. Strength, modulus, initial stress field, and unloading due to excavation are reflected in this analysis. The pore-pressure dissipation behaviour is investigated by employing an uncoupled consolidation theory using finite elements. A dimensionless time factor is used to present the results of pore-pressure dissipation. These results are presented using nondimensional quantities and in normalized forms. The results are directly a...

The flat dilatometer test. final report

Abstract: A dilatometer test consists of pushing a flat blade located at the end of a series of rods. Once at the testing depth, a circular steel membrane located on one side of the blade is expanded horizontally into the soil. The pressure is recorded at three specific moments during the test. The blade is then advanced to the next testing depth. The design applications of the dilatometer test include: deep foundations under horizontal and vertical load, shallow foundations under vertical load, compaction control, and any other geotechnical problems which can make use of the soil parameters obtained from the dilatometer test.

Soils and foundations for architects and engineers

Abstract: The purpose of this book is twofold: (1) To serve as a textbook for architectural and engineering students in undergraduate and graduate level courses, and (2) To serve as a reference for architectural and engineering practitioners The following chapters are included: (1) Classification of Soils; (2) Physical Properties of Soils; (3) Subsurface Soil Exploration; (4) Allowable Soil Bearing Pressure; (5) Spread Footings; (6) Piles, Piers and Caissons; (7) Lateral Earth Pressure; (8) Walls--Construction Details; (9) Walls--Design Considerations; (10) Soil Compaction; (11) Expansive Clay; and (12) Characteristics of Rock Appendices address the following: (A) Earth Pressure Transfer at Cold Joint by Shear-Friction; (B) Earth Pressure Transfer at Cold Joint by Shear Key; (C) Pressure Distribution within a Soil Mass; (D) Basement Slab on Ground--Empirical Design; (E) Dowels for Load Transfer into Footings; and (F) Buoyancy An Index is provided

Reinforced soil back filling construction method for rigid wall

Abstract: PURPOSE:To reduce earth pressure applied to the back of a wall with space temporarily produced between the wall and soil for filling by filling back reinforcing soil by use of sheet-like reinforcing agent when filling back the rigid wall. CONSTITUTION:On the back of a rigid wall 1, a spacer 2 made of foam styrene for supporting space is arranged. In the next step, on the back of the spacer 2, soil 3 for back filling is scattered up to the specified thickness and rolled and compacted. Sheet-like reinforcing agent 4 is arranged. Then, the spacer 2 is removed. This method reduces the earth pressure against the bulkhead by filling back soil 3 and wall thickness, and enables economical design.

The behaviour of laterally loaded two-pile groups

Abstract: The response of piles and two-pile groups to lateral loading has been studied by field tests and computationally. Due to the lack of field test data and because of uncertainty concerning the pile/soil system it has been suggested that further experimental studies of pile groups under lateral loading should be undertaken. The research was conducted through a series of tests on vertical single piles and two-pile groups at various spacing and pile cap overhang heights, to identify the lateral stiffness, bending moment and axial force distribution. Attempts were also made to measure the in-situ total lateral soil pressure on the pile walls. Piles were designed to behave as "long" pile since most piles used in the U.K. are long and flexible. Piles were instrumented with strain gauges for measurement of bending moments and axial forces. Field tests were conducted in a sand trench using 4.0m long piles. A stiff steel pile cap was used to connect head of the two piles firmly together. Linear elastic back analyses of single pile tests were carried out to estimate the soil modulus profile with depth. Thereafter comparisons were made between the field test results on two-pile groups, published analyses and also a three dimensional finite element analysis. Tests results showed that the lateral stiffness of a two-pile groups tends towards a limit as spacing increases. A similar result was found from predictive and finite element analyses. The ratio between the maximum pile shaft bending moment and horizontal force varied between dry and wet season, being greater in the latter. The ratio between maximum reverse bending moment and horizontal load increased as the pile spacing and the overhang increased. Similar results results were found by finite element analysis. One of the main achievements in this research was the measurement of the axial forces in the vertical piles due to lateral loading. It was found that as the pile spacing increased and pile cap overhang height decreasd the peak axial forces per unit load decreased. Similar results were obtained by three dimensional finite element analysis.

Internal stability of reinforced soil retaining structures with cohesive backfills

Abstract: Reinforced soil retaining structures typically are constructed with cohesionless backfills. It is not uncommon, however, that for economic reasons or because the desired cohesionless backfills are unavailable, locally available cohesive soils are used to construct retaining structures. Little information on the performance of reinforced cohesive soil retaining structures is available. Thus, the performance data of some field and model tests and the results of analysis concerning the internal stability of the structures reinforced with polypropylene strips are presented. The in situ testing was conducted for three retaining structures in China, and the model tests were performed in the laboratory of the Changsha Railway Institute. Data analyzed include lateral earth pressure, vertical pressure, tensile strip force, rupture surface, and lateral facing deformation. The results of analysis show that the lateral earth pressure along the back side of the facing decreases with depth from at-rest pressure at the top to less-than-active pressure at depth. The vertical pressure distribution along the base of backfill is not uniform; the shape of distribution appears to vary with the stiffness of the soil-reinforcing system. Along reinforcing strips, the strip tensile force exhibits a peak formation, and the peak location is closer to the facing at the bottom than at the top of the backfill. The potential sliding surface cuts the top of the backfill at a distance of about 28% of the facing height in cohesive backfills rather than 30%, which is generally taken for cohesionless backfills. The available data reveal that structures built with more plastic cohesive backfills may exhibit greater time-dependent performance. It is concluded that reinforced soil retaining structures can be constructed satisfactorily using low to slightly medium plastic cohesive backfills if an adequate drainage system is provided. However, more field data are needed to investigate the long-term stability of reinforced soil retaining structures constructed with more plastic cohesive backfills.

Control method for continuous soil ameliorator

Abstract: PURPOSE:To make the improved state of soil adjustable as well as to prevent a spout of earth and sand or the like from occurring by expanding or contracting a plug zone at a casing rear end according to the driving torque of a motor driving a screw, or opening or closing the gate of an earth discharge port otherwise. CONSTITUTION:Driving torque in a motor 6 driving a screw conveyor 5 of a continuous soil ameliorator is detected,a nd a plug zone 5d installed at the rear end side of a casing 5a of the conveyor 5 is extended or contracted according to this driving torque. Length of a plug being formed there is adjusted, thereby making the degree of soil improvement controllable. In this connection, it may be allowable that a gate 5h installed in an earth discharge port 5i is controlled for its opening or closing and length of the plug is made adjustable. Even if there is produced any ameliorative failure due to the shortage of an ameliorant, earth movement is made so as to make it impossible till it is densified to the plug resistible to earth pressure in a chamber 1a, whereby a spout of soil and groundwater is surely prevented.

Behavior experimenting apparatus for deep layer subsoil

Abstract: PURPOSE:To enable observation of a stress condition under the ground and behavior of a subsoil material in the perimeter of an underground construction model by pressurizing a mobile side plate and a mobile bottom plate from outside to make the subsoil material compressed triaxially while the underground construction model is loaded horizontally. CONSTITUTION:A soil cell 1 is made up of a fixed upper lid 1a, a mobile side plate 1b and a mobile bottom plate 1c and an external frame 2 is provided on an outer circumference of the cell 1. The mobile bottom plate 2a and the mobile side plate 2b of the frame 2 are provided with jacks 3 and 4 equipped with load cells 3A and 4A. A soil manometer and a shear force meter are mounted on the outer circumferential surface of a shaft model 6 and a displacement meter is mounted near the lower part of the model 6. Then, the model 6 is installed in the cell 1 and a subsoil material (e.g. Toyoura standard sand) is fed to prepare a sample. Subsequently, the sample is compressed triaxially to measure a load applied with the load cells 3A and 4A and a soil pressure distribution is measured with a soil manometer. Moreover, the model 6 is pressed with an actuator 9 to measure a soil pressure or the like.

Design Method for Frozen‐Soil Retaining Wall

Abstract: A design method for a frozen-soil retaining wall is presented based on the flexural theory. The method assumes that the frozen wall behaves as a cantilever retaining wall under lateral earth pressure. Because of the complex nature of a frozen soil, the main purpose of the design method is to determine the required thickness of the frozen wall so that its creep stress, creep strain, and creep deflection are within safety limits. Since a frozen soil behaves differently under tensile and compressive stresses, the method uses both tensile and compressive material properties of the frozen soil in computing flexural stresses and strains. Equations developed previously are extensively simplified and made more suitable for design purposes. Design charts are developed to enhance the design process. Assumptions and safety factors in the design process are also discussed, and a design example is presented.

Back-fill injection work

Abstract: PURPOSE:To reduce the cost of construction by a method in which a blowing agent is injected while mixing soil with a hardener into a place by a pump and a quick setting agent is also charged immediately before placement for in-situ back-filling work. CONSTITUTION:Excavated soil is mixed with a hardener such as specific cement, and a blowing agent is injected into the mixture to form an expanded slurry. The slurry so formed is sent under a pressure to a back-filling place by pump, where the unit volume weight of the back-filling material 6 is made smaller than that of soil by adjusting the mixing ratio of excavated soil and hardener and the injecting amount of the blowing agent and also the unit volume weight of the soil is equalized with or made slightly greater than that of water. Since the unit volume weight of the material 6 is small when revetment is constructed, lateral soil pressure to the revetment wall 5 is small and the needs for enlarging the wall 5 is eliminated. The constructing cost can thus be reduced.

Design of Tied‐Back Walls for Seismic Loading

Abstract: A finite element model is used to evaluate seismic behavior of static and seismic tiedback retaining wall designs Two static designs are tested The first design assumes active earth pressure resulting in a single‐anchor design The second static design uses a rectangular apparent‐pressure diagram, resulting in a two‐anchor wall These two designs are then modified using the Mononobe‐Okabe (M‐O) method to account for seismic loading Results illustrate that static earth pressure design assumptions critically impact seismic response The earth‐pressure magnitude and distribution assumed for static conditions are as important to seismic behavior as application of the M‐O seismic design Not only does the two‐anchor static design suffer less displacement than the single‐anchor static design; it also exhibits less displacement than the single‐anchor seismic design The two‐anchor seismic design suffers less displacement than the two‐anchor static design, only at accelerations greater than 02g The effect of

Electric pressure transducer

Abstract: PURPOSE:To improve the very weak underground dynamic pore water pressure measuring accuracy of a pressure transducer by eliminating the influence of the magnitude of a hydrostatic pressure caused by the depth of water or earth pressure on the measurement CONSTITUTION:The peripheral edge section of a discoid strain starting section 1 is united to the internal surface of a main body section 2 Pressure receiving plates 4 and 4 are respectively fitted to both ends of a pressure receiving rod 3 fixed at the center of the section 1 Strain gauges 6 are fitted to the section 1 Bellows 5 and 5 are respectively fitted between the plates 4 and 4 and section 2 in airtight state and hollow chambers are formed in the bellows 5 and 5 Filters 9 and 10 having different mesh sizes, namely, different attenuation characteristics are provided around the plates 4 and 4 When this transducer is buried in the sea bottom, the hydrostatic pressure generated by the depth of water acts on the plates 4 and 4 through the two filters 9 and 10 and offset each other, but a dynamic pore water pressure having a high frequency passes through the filter 9 having the rough mesh size and acts on the plate 4 Therefore, only the dynamic pore water pressure can be detected with the strain gauge 6

Modeling soil reaction to laterally loaded piles

Abstract: A numerical study was made for linearly elastic soil-pile conditions to clarify the lateral soil-reaction behavior of a pile. The apparent lateral stiffness of soil is strongly influenced not only by the soil stiffness but also the geometry and the stiffness of a pile. Also, the apparent lateral stiffness of soil varies significantly with depth, even if the soil stiffness is constant with depth. A new and improved procedure for estimating the lateral soil springs that can be used with the beam-on-Winkler foundation model of a soil-pile system is presented. With these soil springs the beam-on-Winkler foundation model can reproduce with excellent accuracy the pile responses computed from the corresponding continuum system. Although limited to linearly elastic soil-pile conditions, the results may be expanded to nonlinear soil conditions.

Shield excavating method

Abstract: PURPOSE:To provide an improvement in mud pressure shield method. CONSTITUTION:A shield excavator having a rotating face cutter part, a soil pressure chamber, a stirring mechanism for stirring the soil in the soil pressure chamber, a mechanism for discharging the soil in the soil pressure chamber, and a filling material guide pipe for injecting a filling material into a face is operated, and a soil layer is excavated while injecting the filling material into the face surface or the soil pressure chamber. As the filling material, a siliceous aqueous jelly is used. The improvement in soil value in respect to flowability and water stopping property can be performed without accelerating the separation from the excavated earth and sand. Thus, problems such as stop of shield excavation and face breakage can be solved. Further, the mixed excavation muck discharged in this way can be treated as a general earth as it is dried while leaving as it is and the water content ratio is reduced below a half.

Design of embedded retaining walls in stiff clays

Abstract: Increasing use is being made of embedded retaining walls for the construction of roads below ground level in urban areas. This report considers the design requirements of these types of structure in heavily overconsolidated sedimentary clays on which many urban areas in England are founded. The Report reviews methods of determining wall stability and of assessing the structural loading in service. Results from simple limit equilibrium calculations are compared with predictions from numerical analyses. Attention is drawn to the importance of wall flexibility, the initial in situ stress state in the ground and the effects of excavation on the equilibrium pressure distributions likely to act on embedded walls in stiff clays in the longer term. (A)

Reliability of earth pressure measurements adjacent to a multi-propped diaphragm wall

Abstract: Field monitoring data from one panel of a multi-propped diaphragm wall in a stiff fissured clay have been analyzed to investigate their internal consistency. Measured total earth pressures have been assessed in the light of measured prop loads and wall rotations. The raw earth pressure data are shown not to satisfy the fundamental requirements of equilibrium, and to fit poorly with measured wall rotations. However net earth pressure distributions have been constructed which do show consistency with all the other data. These imply that the measured earth pressures, while giving the right general picture, may be over or under recording by up to a factor of two. (A) For the covering abstract see IRRD 860485.