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Segmental retaining walls (SRW), typically constructed along highways, have grown in popularity over the past decade. Manufacturers of SRW blocks have estimated the service life of a properly constructed wall to be approximately 75 years. However, there have been reports of SRW systems failing after only five years in service. Suspected causes of the SRW failures are freeze-thaw damage while exposed to deicing salts sprayed by snow plows from highways. The current standard test method used for evaluating the freeze-thaw durability of SRW blocks has several drawbacks and does not accurately replicate environmental exposure field conditions. The objective of this research is to develop and assess a new standard test method for evaluating the freeze-thaw durability of SRW blocks that obtains reproducible results and offers sufficient information on the freeze-thaw performance for SRW block manufacturers and state highway agencies (SHAs). The research completed a preliminary proof of concept test for the new freezethaw test method developed using small, commercially available SRW blocks to mitigate potential problems and establish appropriate test parameters. The testing produced results of freeze-thaw degradation that followed the same modes of failure that has been discovered during field evaluations. After the proof of concept test was completed, a series of freeze-thaw tests were conducted using sets of SHA approved and non-SHA approved SRW blocks. Three different manufacturers’ SRW blocks were evaluated. There was no significant freezethaw degradation of any of the blocks after 200 freeze-thaw cycles, so for two blocks, experiments were extended to 400 cycles using a twelve-hour freeze-thaw cycle. The modification of the test did not result in more rapid deterioration of the SRW blocks. The researchers found that the freeze-thaw durability test method developed herein is beneficial for determining the freeze-thaw performance of the lower quality specified blocks. The test method gives realistic results, which match typical deterioration modes that are common in field settings, in a timely manner. However, the test method for testing SHA quality SRW blocks takes longer times and may not be a reasonable test for such products.

The use of Mechanically Stabilized Earth (MSE) wall structures has increased dramatically in recent years. Traffic barriers are frequently placed on top of the MSE wall to resist vehicular impact loads. The barrier systems are anchored to the concrete in case of rigid pavement. Nevertheless, in case of flexible pavement, the barriers are constructed in an L shape so that the impact load on the vertical part of the L can be resisted by the inertia force required to uplift the horizontal part of the L. The barrier must be designed to resist the full dynamic load but the size of the horizontal part of the L (moment slab) is determined using an equivalent static load. Current design practice of barriers mounted on top of MSE retaining wall is well defined for passenger cars and light trucks. However, the information of this impact level is extrapolated to heavy vehicle impact. Therefore, the bases of this research is to develop design procedure and to help understand the dynamic behavior of a barrier-moment slab system on top of an MSE wall when subjected to heavy vehicle impact loads. In a first part, numerical analyses were conducted to better understand the behavior of the barrier-moment slab system when subjected to heavy vehicle impact loads. The full-scale impact simulations were used to develop the recommendation for designing and sizing the barrier-moment slab system. In a second part, the barrier-moment slab systems defined to contain heavy vehicle impact loads were placed on top of an MSE wall model to study the kinematic behavior of the system. Loads in the soil reinforcing strips and displacements on the barriers and wall components are evaluated to define recommendation for design of strip reinforcements against pullout and yielding. In a third part, a full-scale crash test on a barrier-moment slab system on top of an instrumented 9.8 ft. (3 m) high MSE wall is described and analyzed. The MSE wall and barrier system were adequate to contain and redirected the vehicle and, therefore, it served as verification of the proposed recommendation. Finally, conclusions are drawn on the basis of the information presented herein.

This research report presented is an engineering analysis of the damage to the Los Angeles River Floodway System by the 1994 Northridge Earthquake. The scope of this research includes: a study of the damage to two specific sections of the L.A. River Channel, a comparison of damaged and undamaged sections of the floodway channel, an analysis to determine the mechanisms of damage, and a look at dynamic earth pressure theories and their predictive capabilities. / Master of Science

This thesis presents a unique finite element investigation of the seismic behaviour of 2 retaining wall types – a rigid retaining wall and a cantilever retaining wall. The commercial finite element program PLAXIS2D was used to develop the numerical simulation models. The research includes: (1) validating the finite element model with the results of 3 previously existing centrifuge tests taken from literature; (2) investigating the seismic response of rigid and cantilever retaining walls including studying the effects of contribution of wall displacement, wall and backfill seismic inertia and stiffness of the foundation soil; (3) developing analytical methods to concrete the findings of the numerical models. Based on the results of the seismic response of a rigid retaining wall, a unique relationship between the seismic earth pressure and wall displacement has been developed for the active and passive modes of failure. The seismic active earth pressure has been found to be not dependent on the wall displacement while the seismic passive earth pressure has been found to be highly affected by the wall displacement. The maximum seismic passive earth pressure force and relative horizontal displacement are predicted when the ground earthquake acceleration is applied with maximum amplitude and minimum frequency content. The seismic response of the wall was not affected by the ratio of the frequency content of the earthquake to the natural frequency of the wall-soil system. For the cantilever retaining wall detailed structural integrity and global analyses have been carried out. It has been observed that the seismic earth pressure, computed at the stem and along a vertical virtual plane are found to be out of phase with each other during the entire duration of the earthquake, and hence, the structural integrity and global stability should be evaluated and assessed individually. A critical case for the structural integrity is observed when the earthquake acceleration is applied towards the backfill soil and has frequency content close to the natural frequency of the retaining wall, while, for the global stability, the critical case is observed when the earthquake acceleration has maximum amplitude and is applied towards the backfill soil with minimum frequency content. The structural integrity is also found to be highly dependent on the ratio between the frequency content of earthquake acceleration to the natural frequency of the cantilever retaining wall. The relative horizontal displacement of a rigid and cantilever retaining wall is found to be highly affected by the duration of the earthquake in contrast to what has been observed for the seismic earth pressure force. The structural integrity of a rigid and cantilever retaining wall reduces when the backfill soil has a higher relative density, while the global stability increases when the backfill soil has a high relative density during an earthquake. The results obtained from the analytical methods reveal that the wall seismic inertia force has a significant effect on the structural integrity only for the top of the stem while the base of the stem does not get affected significantly. The modified Newmark sliding block method provided a more reasonable estimation of the relative horizontal displacement of a rigid retaining wall and a cantilever retaining wall compared with the classic Newmark sliding block method.

The current design procedure for cantilever structures on spread footings in the Texas Department of Transportation (TxDOT) is based on horizontal pressure that is calculated by using Rankine's and Coulomb's theory. These are classical Geotechnical Engineering methods. Horizontal earth pressure due to moisture and volume change in high plasticity soil is not determined by these classical methods. However, horizontal pressure on most of the cantilever retaining structures in Texas is determined by following the classical methods. In recent years, a number of consultants have considered the horizontal pressure due to swelling on cantilever retaining structures in Texas. However, the proposed horizontal pressure by consultants is 10-20 times higher than the classical horizontal pressure. This method of cantilever retaining structure design without knowing the real pressure and stress pattern increases the thickness of the wall, and raises the cost of construction. This study focuses on providing adequate patterns of lateral earth pressure distribution on cantilever retaining structures in expansive soil. These retaining wall structures are subject to swelling pressures which cause horizontal pressures that are larger than the classical especially near the ground surface. Beside the prediction of lateral earth pressure distribution, the relations between water content, volume change and suction change are determined. Based on the laboratory testing program conducted, Soil Water Characteristic Curves (SWCC) are determined for a site located at the intersection of I-35 and Walters Street in San Antonio, Texas. Additionally, relations between volume change with confining pressure curve, water content change with the change of confining pressure curve, water content change with change of matric suction and volume change with change of matric suction curves are generated based on laboratory tests. There are a number of available mass volume measurement methods that use mostly mercury or paraffin to obtain volume measurements. Although these methods are reported in the literature, they are not used in practice due to application limitations like safety, time, and cost. In order to overcome these limitations, a new method was developed to measure the volume of soil mass by using sand displacement. This new method is an inexpensive, safe, and simple way to measure mass volume by Ottawa sand.

The subject of this thesis is the design of a local road cut off in the resort Hálův mlýn located in the cadastral of municipality Lažánky, Brno-venkov district, South Moravian Region. The thesis contains static calculation and design documentation.

The purpose of this paper is to evaluate the performance of a Welded Wire Retaining Wall and present design recommendations for its future use. Field data from the instrumentation of a Welded Wire Retaining Wall as well as laboratory data from a study of welded wire fabric as a reinforcing agent for soil was gathered. A study of the theory and practice of reinforced soil construction was made. On the basis of this study and the experimental data obtained, the wall is evaluated and design recommendations presented.

Seismic pressures on displacing or rigid retaining or basement walls have been derived based on the original work of Mononobe and Okabe, who used a shake table to calculate dynamic pressures of displacing retaining walls existing in cohesionless soils. Since this original work was done over eighty years ago, the results of Mononobe and Okabe, colloquially known as M-O theory, have been applied to different conditions, including non-displacing basement walls, as well as changes in soil properties. Since the original work of M-O, there have been numerous studies completed to verify the accuracy of the original calculation, most notably the work of Seed and Whitman (1970), Wood (1973), Sitar (Various), and Ostadan (2005). This has resulted in varying opinions for the accuracy of M-O theory, whether it is grossly unconservative or conservative, as well as its effectiveness for situations where the wall does not displace enough to engage active soil conditions. This study examines (3) different wall cases, a cantilever retaining wall, gravity retaining wall, and rigid basement wall, through an implcit finite element analysis, under simple sinusoidal boundary accelerations. The soil is modeled using the Drucker-Prager model for elastic-plastic properties. The dynamic pressure increment is observed for different driving frequencies, with the anticipation that an in-phase and out of phase response between the soil and structure will be achieved, resulting in both lower and higher than M-O pressure values.