Search

Foundations of buildings and structures are laid with various methods, both deep and shallow foundations. Piling is the most common method of deep foundations while spread footings are often used in shallow foundations, especially in buildings with column frame. An alternative is to use a composite pile foundation where piles and spread footings or piles and a base slab are used to carry the loads. Bored piles are in-situ concrete piles formed by excavating or boring a hole in the ground and filling it with concrete or reinforced concrete. The use of bored piles has so far been limited in Sweden; therefore there are no Swedish standards for the design of bored piles. However, there are Swedish guidelines from 1979 for the design of bored piles founded in frictional soils, published by the Swedish Commission on Pile Research. These guidelines are however not valid for bored piles in clay or boulder clay. The purpose of this study is to present and evaluate various design methods in order to make an appropriate choice of design methods and to present guidelines to assess when bored piles are appropriate based on technical and economical aspects. Owing to the method of construction, bored piles can be formed with various sizes, ranging from large piles which are a few meters in diameter with depths that reach one hundred meters to small and short piles. This huge variation in dimensions makes bored piles useful for deep foundations as well as shallow foundations. Bored piles have many advantages compared to driven piles; they are environmentally friendly because they generate low levels of noise and ground vibrations, are able to carry heavy transverse loads as well as vertical loads and they are economically advantageous compared to driven concrete piles at moderate depths. Bored piles, also known as drilled shafts, have many advantages compared to spread footings especially in boulder clay and other dense soils. Bored piles have a much shorter production time, requir

Resilient modulus tests were conducted on five subgrade soils commonly found in the state of New Hampshire. Tests were conducted on samples prepared at optimum density and moisture content. To determine the effective resilient modulus of the various soils for design purposes, tests were conducted at room temperature and at freezing temperatures. The AASHTO TP 46 test protocol was used for testing room temperature and thawing soils. At freezing temperatures, the CRREL test protocol was used. The results from this test program are presented in this report. In addition, suggested effective resilient modulus for the five soils are presented.

The phenomenon of shear banding in soils has been studied over the last few years at Case Western Reserve University. Prior research was performed on cohesive and fine-grain, angular soils. To complete the study, a coarse-grain sand was used to determine the effect grain size has on the propagation of shear bands. Many state-of-the- art techniques were used to collect the necessary data; these include digital imaging programs and constant mean stress testing devices. Several different variables were examined to determine the effect they have on the development and propagation of the shear band. Some of these parameters include relative density, stress path, and confining pressure. The genesis of the slip plane and the eventual direction of the shear band was monitored using video cameras. At regular times during the testing process, "snapshots" from these cameras were taken and stored as VGA images on a computer. The images were then digitally traced using specifically designed software packages. With the images digitally recorded, a great deal of information could then be calculated; such as the angle of the slip plane and the strains in and around the shear band.

This Coastal Engineering Technical Note (CETN) summarizes methods that can be used to characterize and monitor geological conditions at coastal projects situated in cohesive environments. These are shores where cohesive substrates (glacial till, lacustrine deposits) or erodible rock are the dominant materials that control the coast's erosional response to waves, storms, and water level changes. Cohesive processes are particularly important in the Great Lakes but also at many reservoirs and along ocean coasts where sand supply is limited and a harder stratum underlies the surficial sediment. This note also applies to portions of the gulf coast where lagoonal sediments are exposed, such as Sargeant Beach, Texas. This note does not address the unique engineering conditions caused by the extremely soft, underconsolidated clays and silts of the Mississippi Delta.

A monitoring program to evaluate the effects of beach nourishment material placed on a cohesive shoreline in southeast Lake Michigan was conducted at St. Joseph, MI, by the U.S. Army Engineer Waterways Experiment Station. In conjunction with this monitoring program, this particular study focuses on a 6-km (3.7-mile) section of shoreline extending southward from the jetties of St. Joseph Harbor. Some of the geological variables that affect cohesive shores were investigated. The primary objective of the study was to develop an improved understanding of the relationship between the movement of the cohesionless sediment (both fine and coarse grain components) and the irreversible downcutting of the underlying glacial till at the St. Joseph project site. Data collected during the monitoring program were input into a 2-D numerical model to describe the cross-shore sediment process and to predict the profile response to storm conditions with the influence of the underlying glacial till represented as an erosion-resistant sublayer. The 2-D profile change tests were performed at 10 of the profile locations., Prepared in collaboration with Baird and Associates, Oakville, Ontario, Canada.

This report presents a method for the use of geocomposite drainage systems as a temporary measure to improve the surficial stability of levee slopes. The mechanisms leading to sloughing failure in cohesive soils are discussed. A general overview of the use of geocomposite drainage systems in geotechnical engineering is given. Detailed design steps, ranging from estimation of required flow capacity of the drainage system to selecting the system's layout, and specifying safety factors, are described. An installation procedure and construction details are discussed. The application of geocomposite drainage systems in levees, as detailed in this report, is new; i.e., it is an extrapolation of existing practices. Therefore, it is considered a temporary measure to improve the surficial stability of levee slopes. A full-scale field test is recommended to assess the effectiveness of using geocomposite drainage systems in levees. Such an experiment will likely lead to improvements in design and construction techniques.

The Workshop on Effects of Piles on Soil Properties was held at the U.S. Army Engineer Waterways Experiment Station on 13-l5 July 1993, and this report presents the proceedings of that workshop. The Workshop was conducted to evaluate needs for research to he conducted by the private sector, institutions of higher learning, or Government agencies concerning the changes in soil properties caused by emplacement of piles or other deep foundation elements. Suggestions for research in soil structure interaction, effects of pile driving on soil properties, verification of soil property changes, and methods of testing and numerical modeling for investigating the problems which were developed at the Workshop are included in the proceedings. Papers presented and contributed to the Workshop are also included. Conclusions reached by the Workshop participants indicate that research into the changes in soil properties caused by pile driving is a valid area of inquiry which could lead to improved design techniques for piles and other deep foundation elements. (AN)

This report summarizes research conducted by the Dredging Research Program, Technical Area 2, Material Properties Related to Navigation and Dredging. Goals of Technical Area 2 were to develop new instrumentation and technology for more thorough subsurface investigations at dredging projects and to refine descriptors for better communication of knowledge from Corps geotechnical engineers to dredging contractors.

The variability of rheological properties in fluid-mud suspensions is studied as a function of salinity and sediment concentration. It was found that the steady state shear stress increases exponentially with increasing sediment concentration and increases logarithmically with increasing salinity of the suspension. An analytic model predicting shear stress as a function of electroviscous properties is developed. The model shows that the effect of salts in the suspension is to decrease the zeta potential by compressing the electric double layer, and thereby, elevating the shear stresses acting on the shearing planes at each particle-fluid interface in the suspension. These stresses increase with increasing salt content. The model incorporates the classical double-layer theories of Gouy-Chapman and the Helmholtz-Smoluchowski theory for electrokinetics of charged particles. The model shows good correlation with experimental data at low sediment concentrations where the basic assumptions of the Gouy-Chapman formulation are satisfied. Mixing length arguments show that the elevated shear stresses transport suspended sediment vertically upward across the lutocline, thereby reducing the abundance of suspended sediment directly adjacent to the consolidated bed. This action reduces the deposition rates that were found to obey a power law over several orders of magnitude. This power law was invoked in a vertical advection-diffusion model to calculate the variation in deposition flux with increasing distance along a channel. These calculations were compared with field measurements conducted at two different sites. The calculations based on the power law were found to correctly predict deposition flux behavior in the far field. (MM)

The major purpose of the Dredging Research Program (DRP) was to reduce. the cost of dredging to a minimum consistent with mission performance and environmental responsibility. One means of accomplishing this mandate is to reduce the impact of contract claims associated with dredging projects. (MM)

A user guide is presented for designing and installing plate anchors in the sea bottom using conventional pile driving techniques. This permits use of low cost, highly efficient, mooring anchors to meet a broad range of mooring requirements, including hurricane moorings for ships or other floating structures. This technique is particularly appropriate for heavily congested or confined areas. The anchors are suitable for various bottom deposits, including soft organic silts, overconsolidated clays, dense sands, glaciated soils and corals. Vibratory and impact diesel hammers may be used with a retrievable follower section to insert the anchors into the bottom. They are then pull-tested either horizontally or vertically up to the design loads. This approach provides versatile, easily fabricated anchors, suitable for a variety of situations, that can be installed with readily available marine construction assets. (MM)

This research was to develop techniques for (1) stress normalization of CPT measurements (and geotechnical properties) and (2) CPT prediction of geotechnical properties using cone and sleeve friction resistance values. Stress normalization allows a variable geotechnical property to be reduced to an equivalent value at a standard confining stress. A new concept, the Stress Focus, was identified which provides a basis for understanding soil strength as a function of confining stress. This study demonstrated that sand friction angles for different initial relative densities converge to a Stress Focus at high confining stress (approximately 100 atm), where the strength behavior is similar to that of a sedimentary rock. Dilation of dense sands decreases with increased confining stress until the Stress Focus is reached, as confirmed using historic high pressure triaxial test data as well with CPT measurements from laboratory chamber tests and uniform soil layers. The paths of convergence to the Stress Focus are exponentially related to confining stress and are the basis for development of CPT cone and sleeve friction resistance normalization techniques. The overburden stress at the Stress Focus is soil type dependent. The stress exponent for SPT normalization was shown to be equal to the CPT derived stress exponent. CPT correlations to geotechnical properties were established using both CPT cone resistance and friction ratio. Geotechnical properties, Stress exponent, Sand friction angles, Stress normalization, Soil strength

The 103rd meeting of the Committee on Tidal Hydraulics was held at the U.S. Army Engineer District, Savannah, on 20-22 September 1994. The Savannah Harbor project was the primary focus of the meeting.Technical presentations were made on Savannah Harbor and the effects of removing the tide gate from operation and of deepening the channel in 1992. The Long-Term Management Strategy for dredging and disposal provides for most effective measures for the next 20 years of harbor operation and maintenance. The Savannah River Basin project addresses goals of maintaining water quality and flood protection. A proposed project for deepening Brunswick Harbor was also presented. During the Executive Session, the Committee provided comments on questions about Savannah Harbor posed by the District and reviewed the Grays Harbor Project, Cohesive Sediments Research Newsletter, CTH Bibliography, and the CTH White Paper on R&D. (MM)

This report consists of three chapters: Chapters 1 and 2 deal with erosion test devices and field instrument assemblies, while Chapter 3 is an analysis of published erosion rate of bed shear strength data in an attempt to establish a functional link between the characteristic erosion rate constant (defined as the slope of the erosion rate-bed shear stress plot). A wide range of erosion test devices has been used both in the laboratory and in the field in the effort to further elucidate the phenomena of cohesive sediment erosion. They differ in configuration and flow geometry, size, mechanisms of generating flow, operation protocol, and measurement methodology. These devices are further complemented by various custom designed field instrument assemblies, which provide valuable prototype data for model calibration and validation. The report reviews six categories of laboratory erosion test devices and eight categories of field devices/measuring assemblies. For each category, a representative device from the literature is described with a view to illustrating its salient features and typical test results. Similarly, the field instrument assemblies are individually described, including a brief discussion on typical field results. The description is confined to a documentation of the suite of equipment with incidental comments on their merits without an effort to compare them on a relative basis.

Three-dimensional stress-strain measurements provide valuable insight into the behavior of sensitive clays during consolidation. Incorporating the ideas of those researchers who have previously measured lateral stresses in clays during consolidation, a new oedometer was designed and constructed specifically to measure lateral stresses in sensitive San Francisco Bay Mud. The new oedometer was evaluated and found to be an acceptable and inexpensive alternative to costly off-the-shelf lateral pressure devices. The results of three tests on San Francisco Bay Mud are analyzed by examining stress paths and compression curves. A visible break on the stress paths occurs ssimultaneously with the sharp break on the arithmetic compression curve, indicating a collapse of the sensitive clay structure. The pressure at which this break occurs is taken to be the yield stress of the clay. The test results are compared with various other methods for determining the yield stress in clays. (MM)

Discontinuities in the form cracks or fissures and inclusions are often present in natural clays. They serve as stress concentrators when loads are applied to the material. Such concentrations result in the cracks advancing, often surrounded and preceded by a propagating damage zone. As the crack propagates, the damage may be in the form of one or more shear bands, which may play the part of new stress concentrators and blunt the action of the original crack. This report examines some of the phenomena associated with the presence of cracks in overconsolidated clays as well as in the less brittle normally consolidated clays. Differences between isotropic and anisotropic materials, and the level at which serious modifications take place in the fabric of the material are noted. Observations made with a surface analyzer as well as with a transmission electron microscope indicate that the changes in fabric mostly occur at the level of the cluster or flock. The influence of the cracks and of the shear bands on the kinematics and strength of the test specimens is studied and discussed.

This report contains Appendices I through IX which consist of data obtained from soil tests. The cell pressure during K sub o consolidation was 620 kPa resulting in a vertical stress of 1240 kPa. The rebound was such that the excess vertical stress was removed and the cell pressure reduced by a factor of 3. This operation leads to an overconsolidation ratio of 4 when reference is made to the mean effective stress. For isotropic specimens consolidation and rebound were spherical in nature. The specimen was hydrostatically consolidated under 620 kPa and rebounded to 207 kPa., See also main report ADA250896.

This report focuses on laboratory tests performed by the US Army Engineer Waterways Experiment Station (WES) to evaluate the performance of three geotextiles with four soils from the Bonnet Carre Spillway area. The purpose of this evaluation was to produce methodologies to assess the feasibility and value of using geotextiles under conditions that exist in the US Army Engineer District, New Orleans. Laboratory-measured parameters of the geotextile/soil systems in question are compared with prototype field tests and used in the analysis of full-size soil structures to evaluate configurations for strength, economy, and effectiveness. This report focuses on the equipment, performance, and results of the WES laboratory study. Bonnet Carre Spillway, Soil/geotextile system, Geotextiles, Soils., Work was performed under Intra-Army Order No. CELMNED-90-56, dtd 30 May 1990.

This research uses theoretical analyses to investigate the fundamental mechanisms controlling the performance of common in-situ penetration tests which are used to estimate the engineering properties of cohesive soils. The mechanics of penetration processes are modelled using the Strain Path Method together with generalized effective stress soil models. The analytical predictions provide a rational basis for establishing how soil properties are related to in-situ measurements. The predictions are evaluated by comparison with field data from well documented test sites. Results of this research show the following: (1) The cone resistance and excess pore pressures measured on the face of the cone during piezocone penetration are the most reliable measurements for estimating changes in undrained shear strength within a given clay deposit. (2) There is no rational basis for correlations between dilatometer contact pressures and in situ K sub O stresses, undrained shear strength or preconsolidation pressure. (3) Model predictions provide a reliable basis for estimating the horizontal coefficient of permeability for normally and lightly overconsolidated clays (OCR<4) using measurements of pore pressure dissipation on the shaft of the piezocone. (4) Installation disturbance affects significantly the interpretation of undrained shear strength in pressuremeter expansion tests. The analyses show that undrained shear strength can be estimated more reliably from measurements during the contraction phase of the pressuremeter test.

A physical model test consisting of a vertically inclined submerged turbulent jet impinging upon a horizontal brick-like clay sample was conducted. Using dimensional analysis the controlling parameters were identified. The data was collected and analyzed to determine the functional relationships between time duration of scour impingement, shear strength of clay, distance of separation between sample and jet, and angle of inclination of jet. It was shown that a linear relationship existed between the scour volume and time of impingement. Furthermore, a relationship existed between the shear strength of the clay and the scour rate and volume. However, the primary governing parameter of scour rate and volume was the tractive shear stress resulting from the impinging jet. The tractive shear stress was varied by changing the angle of inclination and distance of separation of the jet. Theses.

Predictive modeling of estuarial fine sediment transport requirement a description of the erosional properties of cohesive sediment beds. Descriptions are commonly based upon flume experiments run on remolded beds. Field data pertaining to the laboratory erosion process are scarce, so it is unknown how well these estimates relate to the actual erosion process. A field experiment was conducted in a muddy estuary, Mare Island Strait, California. Using a bottom-mounted frame and a moveable instrument sled, suspended sediment concentration and current velocity data were collected in the bottom boundary layer. The critical shear stress of erosion initiation and the erosion rate coefficient were determined from the data. It was found that flume experiments using naturally deposited sediment beds do a reasonable job in predicting both of these parameters, but that experiments using remolded sediments do not approximate the conditions encountered in the field. (MM)

A laboratory investigation was conducted to assess the influence of suction on the shear strength of unsaturated soil. Variables included the effects of compacting specimens of an expansive clay at different water contents, shearing specimen at various densities, and adding potassium chloride (KCl) to pore fluid of selected specimens. It was determined that shear strengths were dependent on the applied stress, density and water content of specimens at failure. A modified Mohr-Coulomb strength relationship was proposed to predict the shear strength of unsaturated soils. The effect of matrix suction was to increase the value of the cohesion intercept in this model. A method was proposed to characterize the influence of matrix suction on the shear strengths of unsaturated soils. It was determined that the magnitude of a suction depended on water content and the degree of saturation of the saturated specimens at failure while the effect of suction was a variable which was dependent upon the degree of saturation of the specimens. Elected specimens were treated with KCl prior to compaction. The effect of solute suction was to increase the value of the cohesion in the modified Mohr-Coulomb strength relationship. Keywords: Soil mechanics; Saturated soils; Soil stabilization; Soils/compacting/expansion; Shear strength; Pore pressure; Clay/montmorillonite; Potassium chloride; Soil tests; Moisture content; Cohesive soils.

The purpose of this manual is to provide guidelines for calculations of vertical displacements and settlement of soil under shallow foundations supporting various types of structures and under embankments.

This research uses theoretical analyses to investigate the fundamentals controlling the performance of common in situ penetration tests (piezocone, pressuremeter, dilatometer, field vane etc.) which are used to estimate the engineering properties of cohesive soils such as clay. The mechanics of penetration processes are modeled using the Strain Path Method together with generalized effective stress soil models. The analytical predications provide a rational basis for establishing how soil properties are related to in situ measurements. Comparisons with field data from well documented sites are used to evaluate the analytical predictions and provide a basis for more reliable interpretation of engineering properties. Research during the second year of the project focused on the following topics: (1) the development of analytical methods to predict pore pressure around three- dimensional penetrometers; (2) fundamental analytical studies of the mechanics of flat plate penetration; (3) application of analytical predictions for interpreting the undrained shear strength and preconsolidation pressure from piezocone data; (4) evaluation of contact pressures measured by the dilatometer; and (5) prediction of the disturbance caused by field vane insertion.

A substantially more robust numerical algorithm for the evaluation of the bounding surface plasticity model for cohesive soils is developed. The robustness of the new algorithm assures accurate results for reasonably sized solution steps and qualitatively correct predictions, even for exceptionally large steps. The improved predictions are illustrated for three examples. Keywords: finite elements; constitutive law; soil plasticity; cohesive soil; numerical implementation.

A study was conducted in an attempt to develop a quantitative method to predict the hydraulic shear stress at which erosion is initiated (critical shear stress) and the rate of erosion of natural soil (with sufficient cohesiveness to allow undisturbed samples to be taken) along a stream bank. In order to obtain a wide range of properties with sufficient geographical distribution, soil and river water samples were requested from Corps of Engineers (CE) Districts in the United States. Preliminary tests conducted on 42 samples included: (a) free swell test on undisturbed soil; (b) dielectric dispersion on remolded soil; (c) slaking test on undisturbed soil; (d) amount of clay present in soil; (e) soil chemistry (pH and soluble cations); and (g) river water chemistry (pH and soluble cations). Based upon the results of preliminary tests 30 soils were selected for detailed analysis which included: (a) index property tests (hydrometer analyses, specific gravity, organic content, gypsum content, moisture content, unit weight, and Atterberg limits); (b) soil chemistry (exchangeable cations); (c) dielectric dispersion on undisturbed soil; (d) flume erosion tests on undisturbed soil; and (e) rotating cylinder erosion tests on saturated remolded soil.

The results of a series of consolidated-undrained (CU) triaxial compression tests performed on normally consolidated and overconsolidated specimes of two clays consolidated both isotropically (ICU tests) and anisotropically (ACU tests) are presented and analyzed in this report. The specimens were trimmed from samples of Vicksburg Buckshot clay (LL = 57) and a clay from the East Atchafalaya Basin Protection Levee (EABPL) project area (LL = 79), both of which had been consolidated from a slurry in large-diameter consolidometers under a maximum vertical consolidation pressure of 3.0 kg/sq cm. Data presented include stress-strain curves, pore pressure observations, final water content distributions within the specimens, and shear strength envelopes based on total and effective stresses. Test results indicate that the change in volume during consolidation and the water content at the end of consolidation are not a unique function of the vertical consolidation stresses but are related to the mean effective consolidation stress. Total stress envelopes based on Taylor's method of deriving strengths of anisotropically consolidated specimens from test results obtained from isotropically consolidated specimens slightly underestimate observed values. In this context, Taylor's method is an appropriate means of predicting strengths for various K sub c ratios from conventional ICU tests. Use of hyperbolic stress-strain relationships derived from ICU tests in finite element codes for ACU conditions will lead to erroneous results. Further testing of anisotropically consolidated soils under stress systems that better simulate in situ conditions is needed.

The results of several repetitive lateral load tests on single piles from previous studies were analyzed. Current techniques for predicting this cyclic and static behavior of piles were reviewed, and predictions of both static- and cyclic-lateral-load behavior were compared with measured behavior. The scour phenomenon that occurs when water above the ground surface flows into and out of any gaps that form between the pile and clay during cyclic loading was examined. Conclusions are drawn related to the relevance of these studies to current procedures of estimating the response of piles in clay due to cyclic lateral loading. Keywords: Pile structures; Load distribution; Cyclic loads; Lateral loads.

Full Text, Thesis (PhD Doctorate), Doctor of Philosophy (PhD), Division of Australian Environmental Studies, Science, Environment, Engineering and Technology, A new model of the erosion by water of cohesive soils is developed using physical principles. The theoretical framework which is developed recognises the changing nature of the eroding surface of a soil. Raindrop impact and overland flow are considered to act upon a soil surface so removing soil from the cohesive original (or parent) soil. Once this soil enters the overland flow, either as aggregates or primary particles, it is considered to return to the soil bed, from which it may be re-removed. The development of a deposited layer makes it necessary to distinguish between processes removing sediment from the original soil and those processes removing the deposited layer. This layer, being formed by the relatively gentle action of deposition during the current erosion event, is presumed cohesionless. The physical properties of the original soil and the deposited layer are considered to be very different. The development of two experimental apparatus, a rainfall/runoff simulator and a settling tube for the measurement of aggregate settling velocities, is first described. Experimental investigations, using these apparatus, and field observations to inform the description of the erosion and deposition processes, are then presented. The processes by which rainfall impact removes sediment from the original soil and the deposited layer are termed rainfall detachment and rainfall re-detachment respectively. Initially, descriptions of these processes in the presence of deposition, are combined in a model describing net rainfall detachment when removal of sediment from the flow bed by overland flow is not occurring. The developriient of the deposited layer is considered both quantitatively and qualitatively. The solution of the equation describing mass conservation is then given for the equilibrium situation when the mass of the deposited layer, and therefore the sediment concentration, is constant with respect to time. The processes by which overland flow removes sediment

Recent investigations on groundshock phenomena indicate that the dynamic response of certain non-linear (locking) media may approximate the behavior of cohesive granular soils and porous rock under high pressures. The theory of wave propagation in such materials should have application to the design of underground shelters at very high pressure levels and may shed some addi tional light, by these relatively simple means on problems associated with phenomena near ground zero, in case of surface bursts or underground explosions.

Difficulties have been encountered in reproducing sufficiently similar dry unit weights (within plus or minus 0.3 pcf) in 1.4-in.-diam triaxial test specimens of cohesive soil compacted using the spring-loaded Harvard miniature compactor. In an effort to alleviate these difficulties, a tamper was made which maintained a constant force on the compacting foot by air pressure acting on a rolling diaphragm. It is designated as the 'modified Berkeley pneumatic tamper.' Calibration and operation showed the pneumatic tamper to be a significant improvement over the spring-loaded tamper. The tamper permits rapid and precise adjustment of the tamping force, with assurance that the tamping force actually applied to the soil is the same for each tamp even when used by different operators. It is believed that laboratories preparing test specimens of cohesive soils by kneading compaction can improve the quality and efficiency of this activity by using a pneumatic tamper.

Relations between cone penetration resistance and relative density were developed by means of statistical analysis (correlation calculation) for three cohesionless soils: Yuma sand, mortar sand, and Bayou Pierre sand. These relations were evaluated from direct measurements of relative density and results of tests with the U. S. Army Engineer Waterways Experiment Station (WES) standard cone penetrometer. Most of the data for Yuma and mortar sands had already been obtained as part of the soil-tire performance tests previously conducted at the WES. However, several special laboratory tests in molds with both sands were conducted to control and extend the existing range of data. The results in Bayou Pierre sand were obtained from laboratory tests conducted especially for this study. The relations established between relative density and cone penetration resistance and its gradient, respectively, averaged over the 0- to 15-cm depth, depend on the grain size and compactibility of the soil. The cone penetration resistance increases with increasing soil mean grain diameter and decreasing compactibility. The critical depth of penetration affects the results within the considered depth range only in loose and very loose sands. A qualitative theoretical explanation of what occurs during the penetration of a cone into a cohesionless medium is given., See also Rept. no. 3, AD878789.

As part of ES 521-A, 'Effect of Maximum Particle Size, Triaxial Compression and Compaction Tests,' compaction tests were performed on a gravelly material with cohesive binder to determine the effect of large-size particles on maximum dry density and optimum water content and to obtain data for use in preparing the triaxial specimens. The effect of mold diameter and the effect of scalping both with and without replacement for oversize material were also investigated.