Showing papers on "Lateral earth pressure published in 1975"

Seismic Design of Reinforced Earth Walls

Abstract: Seismic design for reinforced earth retaining walls was developed largely on the results obtained from small laboratory scale walls on a shaking table, and is therefore tentative and must await verification from further analytical laboratory and field studies. The laboratory tests showed that the walls responded like a nonlinear damped elastic system to the input vibrations. From measurements of the peak tie forces, an empirical design force envelope was developed which is a function of input acceleration only. It is suggested that the design earth pressures for an actual wall subjected to earthquake loading be based on this design force envelope using a base acceleration determined by response spectra and modal participation factor techniques. Data are also presented of soil-tie friction under static and vibratory loading. The recommendations include data from which the required size and spacing of ties can be determined. Suggested factors of safety are given for tie pull out and tie breaking modes of failure.

Wave Induced Pressures in Permeable Seabeds

Abstract: A theoretical investigation on the transmission of wave induced pressures into a permeable sea bottom has been performed. Assuming that the soil water is compressible, while the grain skeleton is assumed rigid, the resulting theoretical model describes an effective mechanism by which the soil permeability affects the pressure transmission.

Some Effects of Dynamic Soil Properties on Soil-Structure Interaction

Abstract: Soils exhibit nonlinear shearing stress-shearing strain behavior as the strain level increases from nearly elastic to plastic conditions. Experimental shearing stress-strain data were approximated by a Ramberg-Osgood mathematical curve which may be incorporated into analytical procedures. The method of characteristics was presented as one analytical method for studying dynamic behavior of soils, fluids, and structures including nonlinear soil behavior, inelastic slip, and transient pore pressures in one and two dimensional systems. Several types of model studies involving soil-structure interaction were presented to illustrate the new method of holgraphic interferometry and to emphasize the importance of test and construction details on the effectiveness of dynamic soil-structure interaction. The importance of positive contact between the foundation block and soil along the vertical faces was noted.

Boundary Wedges in two-dimensional passive soil failure

Abstract: Earth pressure analyses which use a rigid-plastic Mohr-Coulomb soil model generally assume that all the soil within the rupture boundary is deforming and that the loading boundary stresses are fully mobilized The analysis presented here shows that neither of these conditions is always realized and that zones of dead soil develop within the rupture boundary which alter the rupture surface geometry and interface stress conditions It is shown that these zones of undeformed soil, called boundary wedges, are formed either because of kinematic constraints imposed by the motion of the interface or as a result of limitations imposed by interface configuration A systematic method for predicting both the formation of these boundary wedges and their influence on interface stress conditions is presented A calculation procedure, using dimensionless passive coefficients to supplement the charts of those coefficients already published, is set out The theory proposed incorporates into the basic Sokolovski solution t

Side friction in model retaining-wall experiments

Abstract: The paper examines the effect of friction between soil and the sides of the sample box on data obtained from plane strain earth pressure tests on model retaining walls in sand. The relevant literature is reviewed and it is concluded that the side friction can have a significant effect on the measured forces. A new method of calculation, based on that of Sokolovski, is developed to provide a quantitative estimate of the magnitude of the effect of friction. The computational method is described and the results of calculations for a number of active and passive cases are presented. It is found that the effects of side friction are greatest when the sides of the sample box are rough, the angle of internal friction is high, the wall is relatively narrow, and the sand is subjected to passive failure. The small effects of side friction on observed deformations are considered.

New Method for Measurement of Lateral Earth Pressure in Cohesive Soils

Abstract: A new method is described by which the total lateral stress in cohesive soils can be measured. When used in combination with pore pressure measurements, the lateral effective stress, the stress cha...

Investigation of K(o) Testing in Cohesionless Soils

Abstract: : The ratio of horizontal to vertical effective stress when lateral yielding is prevented is known as the coefficient of earth pressure at rest and is denoted by the symbol K(o). K(o) values and the stress-strain response of soils under conditions of lateral restraint are important engineering quantities for problems involving settlement of large fills, lateral pressures on retaining structures, and yielding around excavations. In this report, four laboratory techniques and devices for experimentally determining K(o) values and the stress-strain relationships of Reid-Bedford sand are examined. These methods are: the linear variable displacement transducer (LVDT) clamp, the K(o) belt, swinging arms lateral strain sensors, and an indirect volume change method using a burette. The tests were conducted at three relative densities, 25, 75, and 100 percent, using modified triaxial compression chambers.

Photoelastic Analysis of a Cofferdam

Abstract: Elastic stresses inside the soil mass of a cofferdam are determined using photoelastic technique. A cofferdam model was fabricated simulating the soil mass with gelatin and the steel sheet piles with urethane rubber. This model was tested in a state of plain strain, and, from the photoelastic data, elastic stresses within the fill material were found due to both gravity loading and water pressure. In the gravity loading case, normal stresses agree with the standard theory of soil mechanics for geostatic stresses. Water pressure introducing bending is found to affect the stresses appreciably causing a nonlinear distribution of stresses and pressure on the base of the cofferdam. Contrary to many theories, shear stresses are found to be higher near the sheet pile walls than the midplane. New failure surfaces, in accordance with the elastic stress state, are postulated.

Field Measurements of Ground Displacements About a Tunnel in Soil

Abstract: Soil displacements were measured during the construction of two 21-ft OD shield-driven tunnels in principally granular soil for the Washington, D.C. Metro. The program of field observations and measurements was implemented to determine the relationship of construction procedure to ground movements about the tunnels. Inclinometers, extensometers, and surface settlement surveys measured the soil displacements at three instrument cross-sections in the Lafayette Park Test Section. The soil displacements were measured at a sufficient number of points at each cross-section such that the complete pattern of ground movements at different stages of construction could be determined.

Performance of cells designed to measure soil pressure on earth retaining structures

Abstract: As part of the TRRL research programme to investigate the earth pressures developed against retaining structures, A laboratory study has been made of the performance of three types of pressure cell designed to measure the pressures developed at the boundary between the structural wall and the soil. The three cells tested were a hydraulic, a strain gauge and a pneumatic type pressure cell. The influence of soil type on cell calibrations was studied using washed sand, sandy clay and heavy clay. The relations between applied and recorded pressure for the three types of pressure cell are given for each soil type and the main factors influencing these relations are considered. The errors in cell registration were shown to depend not only on the physical properties of the soil and cell, but also on the nature of the compaction and testing procedure. The study has shown that suitable correction can be made for errors in cell registration provided laboratory calibrations of the pressure cells have been carried out in conditions which closely simulate the situations in which the instruments are to be employed. (A) /TRRL/

New retaining wall design criteria based on lateral earth pressure measurements

Abstract: A procedure for determination of the lateral earth pressure distribution to be used for computation of forces and moments acting on retaining walls which are fixed at their base and backfilled with cohesionless sand are developed. The procedure is based on the analysis of data collected from two instrumented full scale retaining walls. Data are presented covering a period of 1156 days for a cantilever wall founded on drilled shafts. The data consist of pressure cell and movement measurements for both walls. In addition, the force transmitted from the panel wall to its supporting pilasters was measured with force transducers. Structural design considerations and some recommended construction practices are included. Earth pressure distributions and wall movement data are compared with the results of Terzaghi's large scale retaining wall test. This comparison indicates that the foundation of the wall will prohibit the wall from tilting by an amount sufficient to reduce the earth pressures below the at rest value near the base of the wall. Thus for design purposes at-rest pressures are considered to act in this region. Earth pressure changes with time show a seasonal variation in pressure for both walls. The pressure on the panel wall increased as the panel moved outward after backfill. significant changes in pressure appear to result from the movement of construction equipment during backfill and afterward. However, vehicular traffic after construction did not produce measurable changes in pressure during the time periods covered. /FHWA/

Performance of tied-back excavation at Water Tower Place

Abstract: The earth retention system used for the construction of a four-level underground garage at the Water Tower Place project, located in Chicago, Ill., is described. The excavation covered an area of 530 by 212 ft and extended to a depth of 44 ft below ground surface. It was supported by a cast-in-place reinforced concrete wall, 30 in. thick, 62 ft deep, installed by the slurry trench method. The wall spanned between the shafts of perimeter foundation caissons spaced 30 to 31 ft on centers, bearing on "hardpan" at a depth of 88 ft. The shafts were designed to carry part of the lateral load and were encased in a steel shell % in. thick to a depth of 72 ft. The slurry wall was supported at two levels: by a row of grouted earth anchors at the upper level 11 ft from the top, and by inclined rakers at the lower level 27 ft from the top. Performance of the earth retention system was monitored by load cells on tiebacks, strain points on rakers, inclinometers, and by surface measurements. The load carried by each tieback at the completion of substructure was measured by a hydraulic jack. Measured loads are compared with those predicted by the commonly used earth pressure theories. Terzaghi and Peck's pressure diagram appears to fit the observed data. Lateral displacements were generally comparable to those recorded elsewhere for excavations supported by concrete walls and tiebacks. Vertical displacements contiguous to the cut were much less than the predictions based on settlement data reported by Peck for basement excavation in the downtown Chicago area.

Consideration of groundwater pressure on linings of pressure tunnels and shafts

Abstract: In the construction of the Catskill Aqueduct (USA) up to 50 km of 4.3-m-diameter tunnels for a flow of up to 26 mS/see were driven; the internal head h of the water being transported reaches 225 m. A steel facing was incorporated into the tunnel lining; in this case the external groundwater pressure relieving the lining stresses was taken into account. Where the route of the tunnel passed under the bed of the Hudson River the internal head in the tunnel reached 460 m at an external head of the groundwater H = 340 m [1]. During construction of the diversion pressure tunnel for the Tereblya-Rika hydroelectric station (h = 24-28 m) with an inside diameter of 2.5 m and 3610 m long, calculated for a maximum groundwater head H =48 m, groundwater seeped through the joints and cavities of the lining into the tunnel at a rate of 300 liters/see under a considerable head. The percolating water scoured the grout injected behind the lining and the gunite applied on it. To remove these groundwaters about 1600 holes with a depth from I to 2 m were drilled through the lining into the rock. Into all holes were inserted 38-ram-diameter pipes, threaded for attaching removable pressure gauges. The external groundwater pressure was measured by these gauges; the pressure reached 3-4 technical arm and in sections where it was measured exceeded the design internal water pressure. The presence of an excess groundwater pressure made it possible to eliminate completely or partially the reinforced gunite from the entrance portal to the 19 + 80 m station. More than 600 active drain holes, some discharging up to 1 liter/see were left throughout the entire tunnel length. The remaining holes, with insignificant discharges, were sealed with grout and plugged. Observations showed that during tunnel operation leakage from it did not occur. Conversely, the groundwater flowed through the drain holes into the tunnel. This was confirmed by long-term observations of control holes drilled on the exit slope along the route of the penstock in the immediate vicinity of the tunnel and by direct measurement of the water level in the surge shaft with the gates closed at the start and end of the tunnel when this level rose 7 m above the water level in the upper pool [2]. In connection with taking into account groundwater pressure in calculations of linings in soft clays, F. F. Gubin [3] notes that in cases of deep tunnels, when the external earth pressure and groundwater pressure compensate for the internal water pressure in the tunnel, reinforcement of the lining can apparently be omitted. The problem of the distribution of head and, consequently, of pressure in the presence of groundwaters and seepage through the concrete linings of tunnels and the grouting zones surrounding them was first posed and analyzed by G. M. Lomize in his monograph [4, pp. 186-190]. Many conclusions reached in this monograph retain their significance today, especially in connection with the increase in heads and dimensions and depths of underground structares being built in recent years.