published_or_final_version / Civil and Structural Engineering / Master / Master of Philosophy

Traditionally, void ratio, e has been used as a state variable for predicting the liquefaction behaviour of soils under the Critical State (Steady State) framework. Recent publications show that void ratio, e may not be a good parameter for characterizing sand with fines as the steady state, SS data points move downward in e-log(p) space up to certain fines content termed as threshold fines content, TFC. Thus, it was difficult to apply SS concept on sand with fines as a small variation of fines content may lead to different SS line. Many researchers proposed to used equivalent granular void ratio, e* as an alternative state variable (i.e. in lieu of void ratio, e) in attempt to obtain a narrow trend line for SS data points irrespective of fc provided fc  TFC. The e* is obtained from e. For the conversion from e to e*, one need a parameter b which presents the active fraction of fines in overall force structure of sand. However, predicting the b is problematic. Most, if not all, of the b reported were determined by case-specific back-analysis, that is, the b-value was selected so that the test results for a given sand-fines type could be correlated with the equivalent granular void ratio, e* irrespective of fines content. This thesis examines the factors that affecting the b value by examining published work on binary packing. This leads to a simple semi-empirical equation for predicting the value of b based onparticle size ratio,  and fines content, fc. Published data and experimental results on Sydney sand appears to be in support of the proposed equation. The single relation of SS data points in e*-log(p) space for sand with fines is referred as Equivalent Granular Steady State Line, EG-SSL. The EG-SSL is then used to define the equivalent granular state parameter,*. A good correlation observed between * and q-p, q- q responses in undrained shearing. The e* and * are also used to modified a state dependent constitutive model. Seven model input parameters are needed in addition four to critical state input parameters. These parameters are obtained from drained test. The model is used to predict q-pand q- q responses for flow, non-flow and limited flow behaviour for 0% to 30% fines contents. The model predictions are in good agreement with experimental results. The effect of fines types (in terms of plasticity and angularity) on the prediction equation of b are also examined with four different types of fines. A negligible effect of fines type on the prediction equation of b is observed. The link between monotonic and cyclic loading behaviour for sand with fines are also examined with emphasis on cyclic instability and strain hardening behaviour after quasi steady state, QSS for a range of fines contents (provided that fc < TFC). It is found that a single set of rules could be used to correlate monotonic and cyclic behaviour for a range of fines contents at same *.

The soils of Australia have extensive macro and micronutrient disorders varying greatly in their capacities to provide the chemical nutrients essential for plant growth. Assessment of nutrient availability in soils is important in order to maximise fertilizer efficiency and crop yields and to minimise environmental pollution associated with over fertilisation. Nutrient availability has proven difficult to assess due to the complexity of trace element soil chemistry and plant uptake mechanisms. The relatively new method, Diffusive Gradients in Thin Films ( DGT ), provides the potential to become an alternative soil test that could accurately predict nutrient availability. To date, DGT technology has only been designed for separate assessment of anionic and cationic species in waters or soils typically at concentrations characteristic of highly contaminated systems. In this study a new mixed binding gel ( MBL ) was developed capable of simultaneous assessment of cations and anions in a single assay at concentrations more representative of uncontaminated agricultural soils, sediments and waters. The MBL has the potential to eliminate measurement errors associated with very fine spatial scale changes in element concentrations in these environments. The MBL consisted of ferrihydrite and Chelex - 100 cation exchange resin combined together in a binding gel. Results from the MBL were comparable to experiments performed using individual Chelex gels and ferrihydrite gels that have been shown to work successfully for DGT methodology. To facilitate combined analysis of P and cations by ICP - MS, HCl ( 1 M ) was used for gel elution to minimise interferences from [superscript 14] N [superscript 16] OH or [superscript 15] N [superscript 16] O on [superscript 31] P. All elements tested ( Cd, Cu, Mn, Mo, P and Zn ) were bound successfully to the MBL. DGT measurements obtained using the MBL on agricultural soils correlated well ( r ? = 0.95 ) with measurements obtained using pure Chelex and ferrihydrite binding layers. This suggests that the MBL could be used for simultaneous measurement of cationic and anionic element availability in soils. Performance of the Diffusive Gradient in Thin Films ( DGT ) technique was compared with three other common testing methods ( Colwell, Olsen, Resin ) for available soil P in terms of the ability of each to predict wheat, canola, lupin and barley responsiveness to applied P on 21 Australian agricultural soils. DGT accurately predicted plant responsiveness in > 90 % of the soils used. In contrast the other soil testing methods failed to correctly predict plant response to P on numerous occasions. These observations reveal that the DGT technique with the newly developed MBL can predict plant available P on these soils with greater accuracy than other traditional soil P testing methods and could become a useful tool for predicting P fertilizer requirements. The DGT method using the MBL was also used to test Zn deficiency thresholds for canola and wheat in a manufactured soil ( acid washed sand ). DGT successfully determined the threshold for Zn deficiency in this soil, overcoming detection limit issues usually accompanying such low levels of Zn. This method also provides that potential to assess other micronutrients ( Mn, Cu ) and with further modification potentially assess K. Before DGT can become established as an alternative soil testing method, validation of the performance is required under field conditions. This study has shown that it out performs current common soil testing methods in glasshouse conditions but questions still remain if this will be reflected out in the field. / Thesis (Ph.D.)-- University of Adelaide, School of Earth and Environmental Sciences, 2007.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 275-277. / by Maureen Anne Kestler. / M.S.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 163-166. / by Theodore von Rosenvinge IV. / M.S.

Small amounts of cementation in a sand increase its ability to sustain static and dynamic loads, even in a liquefaction type environment. This has been shown in previous research examining the behavior of both naturally cemented and artificially prepared samples. Cemented sands are present in many parts of the world and can be caused by either a variety of cementing agents or by cold welding at points of grain contact. They are generally quite difficult to sample, but artificially cemented sands have been shown to aptly model the behavior of natural materials, and allow for better test controls. Consequently, artificial samples were used exclusively for the present investigation which has three major objectives: to investigate the effects of a weakly cemented lens within a stronger mass; to determine how cementation affects the volume change characteristics of statically loaded samples; and, to describe the pore pressure generation of sands subjected to cyclic loading. Prior to commencing the test program, a number of index tests were performed on the uncemented and cemented sand used during the laboratory investigation. It was revealed that cementation leads to increased void ratios which distort relative density calculations used to compare cemented and uncemented samples of similar dry unit weight. The practice of identifying samples by dry unit weight was adopted for this report. Static triaxial compression tests were performed on 17 samples. Test results indicate that although the magnitude of volumetric strain at failure does not seem to be dictated by the level of cementation, there is a relationship with cementation and the rate of volume change at failure. A weak lens was seen to lower the static strength of the stronger mass. 26 stress controlled cyclic triaxial tests revealed that a weak lens lowers the liquefaction resistance of the stronger mass. The cyclic strength of the nonhomogeneous material, however, is higher than the independent strength of the weak lens. A weak lens has greater influence at relatively higher levels of cyclic stress. Pore pressure generation in cemented sands are seen to be controlled by strain. At shear strain levels below about 1%, cemented sands behave similarly to uncemented sands with pore pressures increasing more rapidly beyond that amount of strain. Consequently, pore pressure development during cyclic loading is described by a broken-back curve which is defined in the early stages by existing empirical relationships for uncemented sand. Pore pressure prediction may then be achieved using an equation for cemented sand, such as that developed in the present work. / Master of Science

Research was conducted in 1984 and 1985 to determine N and P availabilities for barley (Hordeum vulgare L.) and com ( Zea mays L.) grown on four sludge-amended soils. Tests were conducted on the Acredale silt loam (Typic Ochraquall), Bojac loamy sand (Typic Hapludult), Davidson clay loam (Rhodic Paleudult), and Groseclose silt loam (Typic Hapludult) soils. An aerobically·digested sewage sludge from a sewage treatment plant with major industrial irrputs was applied at rates of 0, 42, and 84 dry Mg ha' 1 on the poorly-drained Acredale soil. Rates of 0, 42, 84, 126, 168, and 210 dry Mg ha'1 were applied on the well-drained Bojac, Davidson, and Groseclose soils. The 210 dry Mg haâ 1 sludge rate supplied 3300 and 6600 kg of N and P haâ 1, respectively. A 14-day anaerobic N incubation study indicated that mirreralization varied from approximately nine to four percent of sludge N from the 42 to 210 Mg haâ 1 application rates, respectively. Sludge application increased N uptake (rz = 0.98** to 0.99**) by the 1984 com grown on the three well-drained soils. Nitrogen balance data indicated that quantities of unrecovered N ranged from six to 21 percent where sludge was applied. / Master of Science

Most models available today for predicting the forces encountered by tillage tools apply to slow moving tools and do not take into account speed effects. However, most tillage operations are performed at speeds in the range of 2-8 km/h, and experimental studies show that tool forces increase significantly with tool speed. This effort of developing a model for predicting the forces on narrow tools under dynamic conditions was carried out in three steps. First, a series of laboratory tests was conducted to determine the effect of shear rate on soil shear strength and soil-metal friction parameters. Second, a model was developed to include dynamic effects. Third, the model was verified experimentally under laboratory conditions. Direct shear tests using a conventional shear box were conducted on an artificial soil at shear rates between 0. 5 and 12 7 cm/min. Experimental results showed that for the soil tested, the angle of internal friction, soil-metal friction angle, cohesion, and adhesion are independent of shear rate. A soil-tillage tool interaction model developed for quasi-static soil failure was modified to include shear rate effects and accelerational force effects. Experimental verification tests for the model were conducted under controlled conditions using an indoor soil bin facility. Tests were conducted with flat tines at speeds from 5. 4 to 120 cm/s. The overall trend was for the model to underpredict the observed total tool force by 16 %. However, the model demonstrated that terms including accelerational force effects can account for a large portion of the increase in tool force observed to occur with an increase in tool speed. / Master of Science

A room temperature procedure for the partial extraction of heavy metals from soils was investigated in order to find an optimum combination of acid type, acid strength and digestion period. Hydrochloric and nitric acids were compared. The optimum set of variables would produce a maximum amount of adsorbed metal extraction, with a minimum amount of damage to the soil crystal structures, in the shortest possible time span. Samples were analyzed for aluminum, iron, lead, manganese and zinc. In addition, the amounts of metals extracted by the room temperature procedure were compared with the amounts of metals obtained from both a total extraction and a partial extraction procedure involving heat. The chosen optimum combination technique was performed on a known metals trend area. No clearly optimal combination of acid strength and digestion time was found which would be applicable to varying types of soils; statistical analysis yielded a compromise point of 1.4N hydrochloric acid and 10.5 hour digestion period, as the most suitable combination. This combination of variables proved suitable since predicted results were obtained from the known metals trend area. Nitric acid was eliminated due to the acid’s lower reactivity. Room temperature extractions using strong acids at extended contact times were found to attack silicate minerals, but solutions stronger than have previously been used may be utilized without damage to the soil structure. Extractions utilizing heat and concentrated acids were too destructive to be considered true partial extractions. / M.S.

Undrained triaxial tests were conducted to develop the constitutive relationships for two agricultural soils, which could be used for the finite element analysis of multipass effects of vehicles on soil compaction. Sandy-clay and sandy-silt samples were loaded and unloaded three times to levels of 138 kPa to simulate three passes of an agricultural tractor. An axial loading rate of 200 mm/min was used to include the dynamic effects of rapid loading from the vehicles. An Instron Universal Testing Machine was used to provide this loading rate. During the tests, a microcomputer based data acquisition system recorded axial force and strain. The system recorded 28 values per second. Tests were conducted at four confining pressures; 17.2, 24.1, 34.4 and 41.4 kPa. Plots for deviatoric stress and axial strain were found to be bilinear. Initial and latter portions of the curve were assumed to represent the elastic and plastic deformations of the sample, respectively. Assuming an associated flow rule, an elastic-plastic constitutive model was developed based on a Mohr-Coulomb failure surface. The constitutive model developed was evaluated by simulating a triaxial test at a confining pressure of 28 kPa. Initial conditions were computed by substituting the boundary stresses into the model to determine the elastic-plastic matrix. Incremental loads were applied up to the maximum stress level. For each increment of load, the elastic-plastic matrix was updated from the previous load application. The simulated data compared fairly well with experimental results, but tended to overpredict at higher stress levels. Based on a comparison with existing elastic-plastic models, the derived model appears to be well suited for substitution into the finite element method for studying soil compaction resulting from multipass effects of tractors. / M.S.