The problem of passive earth pressure is one of the important topics in Geotechnical engineering. At attempt is made in this thesis to generate passive earth pressure coefficients for general c-Φ soils using logarithmic spiral failure surface by limit equilibrium approach. Method of slices for the determination of passive force in c-Φsoils is presented and the method is extended to a typical problem of two layered soil system. The application of passive earth pressure coefficients has been demonstrated for pullout capacity of inclined strip anchors in sloping ground. A semi-empirical approach for the determination of displacement-related passive earth pressure is presented. The thesis is organized in seven chapters. In Ch.2, a brief summary of relevant literature is presented along with the scope of the thesis. In Ch. 3, limit equilibrium approach for the determination of the passive earth pressure in soils is presented. The passive earth pressure coefficients are developed for δ/Φ= - 1, - ¾ , -2/3, - ½, 0, ½, ¾ 1; ψ = -60º, -45º, -30º, -20º, -10º, 0º,10º,20º,30º and 45º; i= -30º, -20º, -10º,0º,10º,20º and 30º where δ is the wall friction angle, Φ is the angle of internal friction, Ψ is the inclination of the wall with the vertical and i is the ground inclination with the horizontal. Ch.4 deals with the method of slices. Satisfying all the three equilibrium conditions and using interstice friction as a variable, passive earth pressure coefficients are obtained for soils. Extension of the method to a two layered soil system is demonstrated by an illustrative example. A generalised approach for the determination of uplift capacity of inclined strip anchors in sloping ground subjected to surcharge is presented in Ch. 5. Expressions are provided for the determination of pullout capacity of deep anchors. Displacement-related passive earth pressure is discussed in Ch. 6. Using the earlier experimental observations on the passive earth pressure measurements with displacements, expressions have been fitted for the determination of displacement-related passive earth pressure for the three modes of rigid body movements viz., translation, rotation about the top and rotation about the bottom. The conclusions drawn from the present investigations are listed in Ch 7. (Pl see the original document for abstract)

Low-strength cellular concrete is a type of controlled low-strength material (CLSM) which is increasingly being used for various modern construction applications. Benefits of the material include its ease of placement due to the ability of cellular concrete to self-level and self-compact. It is also extremely lightweight compared to traditional concrete, enabling the concrete to be used in fill applications as a compacted soil would customarily be used. Testing of this material is not extensive, especially in the form of large-scale tests. Additionally, effects of skew on passive force resistance help to understand performance of a material when it is used in an application where skew is present. Two passive force-deflection tests were conducted in the structures lab of Brigham Young University. A 4-ft x 4-ft x 12-ft framed box was built with a steel reaction frame on one end a 120-kip capacity actuator on the other. For the first test a non-skewed concrete block, referred to as the backwall, was placed in the test box in front of the actuator. For the second test a backwall with a 30° skew angle was used. To evaluate the large-scale test a grid was painted on the concrete surface and each point was surveyed before and after testing. The large-scale sample was compressed a distance of approximately three inches, providing a clear surface failure in the sample. The actuator provided data on the load applied, enabling the creation of the passive force-deflection curves. Several concrete cylinders were cast with the same material at the time of pouring for each test and tested periodically to observed strength increase.The cellular concrete for the 0° skew test had an average wet density of 29 pounds per cubic foot and a 28-day compressive strength of 120 pounds per square inch. The cellular concrete for the 30° skew test had an average wet density of 31 pounds per cubic foot and a 28-day compressive strength of 132 pounds per square inch. It was observed from the passive force deflection curves of the two tests that skew decreased the peak passive resistance by 29%, from 52.1 kips to 37 kips. Various methods were used to predict the peak passive resistance and compared with observed behavior to verify the validity of each method.

Full-scale dynamic lateral load tests were performed on a pile cap with a dense silty sand backfill condition. Two hydraulic load actuators connected a test pile cap with a reaction cap. The load actuators incrementally loaded the test cap up to 50 mm of displacement. After each load increment, the displacement was held constant while an eccentric mass shaker induced dynamic loads under a ramping sequence from 1 Hz to 10 Hz. A baseline response was developed under a no backfill condition. Passive soil pressure was measured using pressure cells and tactile sensors. It was concluded that the presence of the backfill significantly increased the lateral load resistance of the pile-cap system, with the resistance nearly doubling at a 50 mm deflection level. After initial loading, the pile cap system experienced a loss in load resistance. In the case with backfill present, this relaxation generally represented a 10 to 15% loss in resistance. Additionally, after undergoing dynamic, cyclic loading, the resistance was approximately 40 to 80% of its initial value. Dynamic displacement amplitudes were on the order of 0 to 2 mm. Passive pressure from the backfill was observed to be non-linear with a concentration of pressure near the bottom of the pile cap. Rankine, Coulomb, and log-spiral earth pressure theories underestimated the passive earth pressure from the backfill by at least 30%. The natural frequency of the pile cap increased with increasing with static displacement level while placement of the backfill further increased the frequency of the pile cap. On average, the presence of the backfill increased the reloading stiffness of the pile cap by a factor of three to four, whereas the damping ratio increased by a factor of two. The dense silty sand backfill acting by itself on the face of the 1.12 m tall and 5.18 m wide pile cap face exhibited a reloading stiffness on the order of 120 to 250 kN/mm and a damping ratio of 30 to 70%. These damping ratios are significantly higher than that typical expected for structural materials but appear to be consistent with values for soils.

Full-scale lateral load tests were performed on a pile cap with five backfill conditions: no backfill, densely compacted fine gravel, loosely compacted fine gravel, densely compacted coarse gravel, and loosely compacted coarse gravel. Static loads, applied by hydraulic load actuators, were followed by low-frequency, actuator-driven cyclic loads as well as higher frequency dynamic loads from an eccentric mass shaker. Passive resistance from the backfill significantly increased the lateral capacity of the pile cap. Densely compacted backfill materials contributed about 70% of the total system resistance, whereas loosely compacted backfill materials contributed about 40%. The mobilized passive resistance occurred at displacement-to-height ratios of about 0.04 for the densely compacted gravels, whereas passive resistance in the loosely compacted materials does not fully mobilize until greater displacements are reached. Three methods were used to model the passive resistance of the backfill. Comparisons between calculated and measured responses for the densely compacted backfills indicate that in-situ shear strength test parameters provide reasonable agreement when a log-spiral method is used. Reasonable agreement for the loosely compacted backfills was obtained by either significantly reducing the interface friction angle to near zero or reducing the soil's frictional strength by a factor ranging from 0.65 to 0.85. Cracking, elevation changes, and horizontal strains in the backfill indicate that the looser materials fail differently than their densely compacted counterparts. Under both low frequency cyclic loading and higher frequency shaker loading, the backfill significantly increased the stiffness of the system. Loosely compacted soils approximately doubled the stiffness of the pile cap without backfill and densely compacted materials roughly quadrupled the stiffness of the pile cap. The backfill also affected the damping of the system in both the cyclic and the dynamic cases, with a typical damping ratio of at least 15% being observed for the foundation system.

The passive force-deflection relationship for abutment walls is important for bridges subjected to thermal expansion and seismic forces, but no test results have been available for skewed abutments. To determine the influence of skew angle on the development of passive force, lab tests were performed on a wall with skew angles of 0º, 15º, 30º, and 45º. The wall was 1.26 m wide and 0.61 m high and the backfill consisted of dense compacted sand. As the skew angle increased, the passive force decreased substantially with a reduction of 50% at a skew of 30º. An adjustment factor was developed to account for the reduced capacity as a function of skew angle. The shape of the passive force-deflection curve leading to the peak force transitioned from a hyperbolic shape to a more bilinear shape as the skew angle increased. However, the horizontal displacement necessary to develop the peak passive force was typically 2 to 3.5% of the wall height. In all cases, the passive force decreased after the peak value, which would be expected for dense sand; however, at higher skew angles the drop in resistance was more abrupt than at lower skew angles. The residual passive force was typically about 35 to 45% lower relative to the peak force. Lateral movement was minimal due to shear resistance which typically exceeded the applied shear force. Computer models based on the log-spiral method, with apparent cohesion for matric suction, were able to match the measured force for the no skew case as well as the force for skewed cases when the proposed adjustment factor was used.

Low-strength cellular concrete consists of a cement slurry that is aerated prior to placement. It remains a largely untested material with properties somewhere between those of soil, geofoam, and typical controlled low-strength material (CLSM). The benefits of using this material include its low density, ease of placement, and ability to self-compact. Although the basic laboratory properties of this material have been investigated, little information exists about the performance of this material in the field, much less the passive resistance behavior of this material in the field.In order to evaluate the use of cellular concrete as a backfill material behind bridge abutments, two large-scale tests were conducted. These tests sought to better understand the passive resistance, the movement required to reach this resistance, the failure mechanism, and skew effects for a cellular concrete backfill. The tests used a pile cap with a backwall face 5.5 ft (1.68 m) tall and 11 ft (3.35 m) wide. The backfill area had walls on either side running parallel to the sides of the pile cap to allow the material to fail in a 2D fashion. The cellular concrete backfill for the 30<&degree> skew test had an average wet density of 29.6 pcf (474 kg/m3) and a compressive strength of 57.6 psi (397 kPa). The backfill for the 0<&degree> skew test had an average wet density of 28.6 pcf (458 kg/m3) and a compressive strength of 50.9 psi (351 kPa). The pile cap was displaced into the backfill area until failure occurred. A total of two tests were conducted, one with a 30<&degree> skew wedge attached to the pile cap and one with no skew wedge attached.It was observed that the cellular concrete backfill mainly compressed under loading with no visible failure at the surface. The passive-force curves showed the material reaching an initial peak resistance after movement equal to 1.7-2.6% of the backwall height and then remaining near this strength or increasing in strength with any further deflection. No skew effects were observed; any difference between the two tests is most likely due to the difference in concrete placement and testing.

Low-strength cellular concrete consists of a cement slurry that is aerated prior to placement. It remains a largely untested material with properties somewhere between those of soil, geofoam, and typical controlled low-strength material (CLSM). The benefits of using this material include its low density, ease of placement, and ability to self-compact. Although the basic laboratory properties of this material have been investigated, little information exists about the performance of this material in the field, much less the passive resistance behavior of this material in the field.In order to evaluate the use of cellular concrete as a backfill material behind bridge abutments, two large-scale tests were conducted. These tests sought to better understand the passive resistance, the movement required to reach this resistance, the failure mechanism, and skew effects for a cellular concrete backfill. The tests used a pile cap with a backwall face 5.5 ft (1.68 m) tall and 11 ft (3.35 m) wide. The backfill area had walls on either side running parallel to the sides of the pile cap to allow the material to fail in a 2D fashion. The cellular concrete backfill for the 30° skew test had an average wet density of 29.6 pcf (474 kg/m3) and a compressive strength of 57.6 psi (397 kPa). The backfill for the 0° skew test had an average wet density of 28.6 pcf (458 kg/m3) and a compressive strength of 50.9 psi (351 kPa). The pile cap was displaced into the backfill area until failure occurred. A total of two tests were conducted, one with a 30° skew wedge attached to the pile cap and one with no skew wedge attached.It was observed that the cellular concrete backfill mainly compressed under loading with no visible failure at the surface. The passive-force curves showed the material reaching an initial peak resistance after movement equal to 1.7-2.6% of the backwall height and then remaining near this strength or increasing in strength with any further deflection. No skew effects were observed; any difference between the two tests is most likely due to the difference in concrete placement and testing.