Thermal Interaction between Permafrost and the Qinghai-Tibet Railway

Measures were taken to protect the thermal regime of the roadbed embankment after construction and to lower permafrost temperatures in the rich-ice and warm permafrost regions along the Qinghai-Xizang Railway. However, these measures were taken only for some sections of the railway, leaving many sections unprotected. This article addresses those areas where no measures were taken and presents analysis of the variation of soil temperatures under the embankment in seasonal frozen soil areas, degrading permafrost areas, and warm and cold permafrost areas. The results show that soil temperatures, maximum seasonal freezing depth, and the permafrost table under the embankment differ according to the different frozen soil areas after embankment construction. In seasonal frozen soil areas and degraded permafrost areas, the seasonal frost layer remained frozen the next year under the shaded shoulder of the embankment. In degrading permafrost areas, a thaw layer between the permafrost table and the bottom of the seasonal frost formed under the embankment. In warm permafrost areas, the permafrost table under the embankment was unstable and soil temperatures near the permafrost table showed an obvious increasing trend. In cold permafrost areas, the permafrost table under the embankment was clearly raised and temperature lowered in the soil near the permafrost table, which is advantageous to permafrost thermal stability under the embankment. In particular, the differ-ence in solar radiation from the slope exposed to the sun to the shady slope of the embankment is responsible for the difference in the soil thermal regime and the permafrost table, which potentially can affect roadbed stability.     

Unfrozen Water in Freezing and Thawing Soils: Kinetics and Correlation

The experimental data indicate that water in freezing or thawing wet soils undergoes a gradual phase change. The mathematical forms of reported correlations of the unfrozen water content of soils varies from researcher to researcher. An improved theoretical treatment of the gradual freezing∕thawing process provides insight into the mechanism of the gradual phase change of water in wet soils and a proper means of correlating experimental measurements. Direct numerical solution of the resulting ordinary differential equation may provide accurate prediction of the unfrozen water content of wet soils, when accurate soil property data are available. Two approximate analytical solutions are derived using average thermal properties of the soil constituents. The simpler of these analytical solutions is applied to various data and shown to be sufficient for all practical purposes. The analysis presented in this article demonstrates that the unfrozen water content can be adequately correlated by means of an exponential decay function shifted by the amount of the water adsorbed over the soil grains, which cannot freeze.     

Effect of Surface Heave on Response of Partially Embedded Pipelines on Clay

The as-laid embedment of an on-bottom pipeline strongly influences the resulting thermal insulation, and the resistance to subsequent axial and lateral movement of the pipeline. Reliable assessment of these parameters is essential for the design of offshore pipelines. Static vertical penetration of a pipe into a soft clay seabed—which can be modeled as an undrained process—causes heave of soil on each side of the pipeline. The heaved soil contributes to the vertical penetration resistance and the horizontal capacity. This paper describes a series of large deformation finite-element analyses of pipe penetration, supported by a simple analytical assessment of the heave process. The conventional bearing capacity approach to the analysis of pipe penetration is reviewed, and modifications for the effects of soil weight and heave are presented. It is shown that in soft soil conditions—which are typical for deep water—the soil self-weight contributes a significant portion of the vertical penetration resistance and horizontal capacity. If heave is neglected, the soil weight leads to a vertical force due to buoyancy, based on Archimedes’ principle. When heave is considered, the soil weight contributes an additional component of vertical load, exceeding simple buoyancy, due to the distorted geometry of the soil surface. Archimedes’ principle does not apply. The finite-element analyses, benchmarked against rigorous plasticity solutions, are used to calibrate simple expressions for predicting static vertical pipe penetration, and the resulting horizontal capacity. These simple solutions allow the conventional bearing capacity approach to be used in a manner which correctly accounts for the effects of soil self-weight and heave. An approximate solution for predicting the “local” pipe embedment—relative to the raised soil level immediately adjacent to the pipe—is derived. The local embedment significantly exceeds the nominal embedment relative to the original soil surface. This effect counteracts the tendency for heave to reduce the embedment by raising the penetration resistance.     

Immunohistochemical studies on sympathetic and non-sympathetic nerve fibers and neuronal cell bodies in the pineal gland of cotton rats, Sigmodon hispidus

This study evaluated the performance of sapphire and fused silica hemispherical tips under the same exposure conditions. Lesions produced in the chicken breast and a blood field were sectioned for light and transmission polarizing microscopy. Lesion size and thermal damage area were recorded as a function of the tips accumulated exposure. The tips transmission was measured after every 1,000 J of exposure. Fused silica tips lasted for approximately 5,000 J and experienced significant surface and transmission deterioration. The sapphire hemispherical tips lasted for > 12,000 J with no surface and transmission deterioration. Lesions produced with the fused silica tips generally increased in depth with use, and depths of 6 mm were common. Lesions produced by the sapphire tips were subsurface spherical areas of coagulation with the tissue surface relatively intact. This difference in resulting lesions may be attributed to the higher thermal conductivity of sapphire.     

Qinghai-Xizang Railroad Construction in Permafrost Regions

Construction of the Qinghai-Xizang Railroad (QXR) in permafrost regions presents a number of significant engineering problems. The engineering properties of permafrost can vary greatly, and climate warming, especially warm permafrost with high ice content, must be considered. Permafrost warming could induce ground ice thaw, producing embankment settlement. Consequently, thermal stability is a key consideration for the QXR construction in permafrost regions. In order to ensure permafrost thermal stability under the background of climate warming, ideas of embankment cooling to preventing permafrost change are proposed. Many methods of embankment cooling have been proposed to prevent the thawing of ground ice. For example, block-stone embankment, block and debris slope protected, thermosyphon, and special bridge designs. The amount of engineering practice and observational data testify that measurements of embankment cooling effectively decrease permafrost temperature and heighten the permafrost table beneath embankments.     

Development of a Four-Phase Remedial Scheme to Clean Up Petroleum-Hydrocarbon Contaminated Soils

In this study, a four-phase remedial scheme was developed for in situ cleanup of petroleum-hydrocarbon contaminated soils. The developed remedial scheme contained the following four phases: surfactant flushing, groundwater flushing, chemical oxidation using KMnO4 as the oxidant, and enhanced bioremediation. Laboratory bench-scale experiments were performed to evaluate the effectiveness of this developed remedial scheme on the treatment of diesel oil contaminated soils. In the surfactant and groundwater flushing batch experiment (the first and second phases), biodegradable surfactant, Simple Green (SG) (5% by weight) was applied to flush diesel oil contaminated soils with initial total petroleum-hydrocarbon (TPH) concentration of approximately 31,500??mg?kg-1. Results show that more than 90% of TPH could be removed after flushing with 40 pore volumes (PVs) of SG, followed by 25?PVs of groundwater. In the KMnO4 oxidation experiment (third phase) with initial soil TPH concentration at approximately 4,900??mg?kg-1, up to 65% of TPH removal efficiency can be obtained when 1% by weight of KMnO4 was applied for oxidation. Results also reveal that the slight increase in TPH removal was observed in experiments with SG addition (0.1% by volume) owing to increased dissolution and desorption of TPH from soils. In the enhanced bioremediation (fourth phase) batch experiments, a petroleum-hydrocarbon degrading bacterium was isolated from the soil materials after the KMnO4 oxidation experiments and identified as Pseudomonas sp. via biochemical tests and further confirmation of DNA sequencing. Results from biodegradation experiments indicate that the isolated bacterium, which survived after KMnO4 oxidation process, was capable of degrading TPH caused by diesel oils, and caused the TPH to drop from 2,105 to 487??mg?kg-1 within 15?days of incubation. The effectiveness of the four-phase remedial scheme was further confirmed by a semicontinuous batch experiment. Results from this study indicate that the four-phase scheme is a promising technology for the treatment of petroleum-hydrocarbon contaminated soils.     

SIMGRO, a GIS-Supported Regional Hydrologic Model in Irrigated Areas: Case Study in Mendoza, Argentina

The SIMGRO hydrologic simulation model was extended to include irrigation practice. It could then be used to evaluate the effect of hydrologic changes in an irrigated area in the province of Mendoza, Argentina where, given an average annual rainfall of approximately 200?mm, irrigation is crucial for agriculture. A storage dam was recently constructed in the Mendoza River to control the fluctuating river flow and to guarantee that the demand for water is met throughout the year. The dam will impact on parts of the irrigation system where groundwater levels are already high and salinization occurs. To evaluate these changes and possible mitigation measures, two performance indicators that consider groundwater and surface water were used: Relative evapotranspiration and the depleted fraction. Scenario runs revealed that the irrigation water losses from the canals affect the groundwater levels in the downstream part of the irrigated area; an increase in salinity was also revealed.     

Intrathecal sufentanil for labor analgesia--sensory changes, side effects, and fetal heart rate changes

This study was designed to evaluate intrathecal (IT) sufentanil for labor analgesia with respect to sensory changes, side effects, and fetal heart rate (FHR) changes. In Phase I of the study, data regarding duration of analgesia and hemodynamic changes were obtained retrospectively from the labor and anesthetic records of 90 patients who had received IT sufentanil, 10 micrograms in 1 mL of saline, during active labor. In Phase II, an additional 18 parturients who received similar treatment were studied prospectively to document sensory, motor, and hemodynamic changes, as well as the incidence of side effects. In Phase I, analgesia occurred rapidly and lasted 124 +/- 68 min (SD); 19% of patients required no further analgesia before delivery. In Phase II, median time to onset of analgesia was 3 min (range 1-6 min) and mean duration of analgesia was 96 +/- 36 min. Decreased sensation to pinprick and cold occurred within 6 min extending from T4 to L4 (upper and lower median levels) in the majority of patients. All subjects requested additional analgesia within approximately 30 min of recession of sensory changes. Motor strength remained normal throughout. Hypotension (systolic blood pressure [BP] < or = 90 mm Hg or > 20% decrease in systolic BP) occurred in 14% and 11% of patients in Phase I and II, respectively. Perineal itching preceded analgesia in 95% of patients and all subjects experienced mild sedation. FHR changes occurred in 15% of cases but were not associated with adverse neonatal outcome.(ABSTRACT TRUNCATED AT 250 WORDS)     

Permafrost Weakening as a Potential Impact of Climatic Warming

The warming weakening of permafrost strength as a result of different scenarios of climatic warming ranging from 0 to 5°C over the next century has been predicted using a one-dimensional geothermal model. These predictions are based on the results of an intensive geotechnical program carried out in a warm ice-rich silty permafrost in Northern Quebec. The dependency of permafrost strength on temperature was assessed from cone penetration tests performed at regular intervals over a 2-month period during the seasonal warming of the upper permafrost layer in spring 2000. A thermomechanical subroutine taking into account this dependency has been then added to the one-dimensional geothermal model for the simulation of the weakening of permafrost strength as it warms. A warming rate of 0.02°C/year over the next century leads on a slow decrease in permafrost strength corresponding to a relative loss of strength of about 50%. For a warming rate of 0.05°C/year, the strength weakening is much more pronounced and almost reaches the unfrozen state at the end of the warming period corresponding to a relative loss of 98%.     

Effects of Groundwater Table Position and Soil Properties on Stability of Slope during Rainfall

Rainfall, hydrological condition, and geological formation of slope are important contributing factors to slope failures. Parametric studies were carried out to study the effect of groundwater table position, rainfall intensities, and soil properties in affecting slope stability. Three different groundwater table positions corresponding to the wettest, typical, and driest periods in Singapore and four different rainfall intensities (9, 22, 36, and 80 mm/h) were used in the numerical analyses. Typical soil properties of two main residual soils from the Bukit Timah Granite and the sedimentary Jurong Formation in Singapore were incorporated into the numerical analyses. The changes in factor of safety during rainfall were not affected significantly by the groundwater table near the ground surface due to the relatively small changes in matric suction during rainfall. A delay in response of the minimum factor of safety due to rainfall and a slower recovery rate after rainfall were observed in slopes from the sedimentary Jurong Formation as compared to those slopes from the Bukit Timah Granite. Numerical analyses of an actual residual soil slope from the Bukit Timah Granite at Marsiling Road and a residual soil slope from the sedimentary Jurong Formation at Jalan Kukoh show good agreement with the trends observed in the parametric studies.     

Case Study of Water Table Evaporation at Ichkeul Marshes (Tunisia)

The method of Gardner was used to estimate the evaporation rate from bare soils under high water table conditions, at Ichkeul marshes, of northern Tunisia. For this purpose, water content, soil-water suction, and water table depth were measured at three sites. Other common approaches that provide estimates of water table evaporation such as the Averianov and Coudrain-Ribstein et al. empirical formulas and the approach used by the U.S. Geological Survey's groundwater flow model MODFLOW were also evaluated. Next, a 2D groundwater simulation model, using the Gardner equations for computing evaporation rate, was developed to quantify the aquifer budget and groundwater losses via evaporation at the total area of the marshes. The model was calibrated in a steady-state condition. The results indicated significant groundwater losses by water table evaporation. The sensitivity of the groundwater model to the Averianov and MODFLOW approaches was analyzed. The best results (piezometric head and the area distribution of the evaporation discharge) were obtained with the Averianov formula.     

Modeling Evapotranspiration of Two Land Covers Using Integrated Hydrologic Model

Modeling evapotranspiration (ET) distribution in shallow water table environments is of great importance for understanding and reproducing other hydrologic fluxes such as runoff and recharge. Unfortunately, ET distribution can be the most difficult hydrologic process to analyze. The partitioning of ET into upper zone ET, lower zone ET, and groundwater ET is complex because it depends on land cover and subsurface characteristics. One comprehensive distributed parameter model, integrated hydrologic model (IHM), builds on an improved understanding and characterization of ET partitioning between surface storages, vadose zone storage, and saturated groundwater storage. It provides a smooth transition to satisfy ET demand between the vadose zone and the deeper saturated groundwater. In this paper, the IHM was used to analyze ET contribution from different regions of the vadose zone and saturated zone. Rigorous testing was done on two distinct land covers, grass land and forest land, at a study site in West-Central Florida. Sensitivity analysis on the key parameters was investigated and influence of parameters on ET behavior was also discussed. Statistics with the root mean square error and mean bias error for forest total ET were about 1.46 and 0.04 mm/day, respectively, and 1.61 and 1.07 mm/day for grass total ET. Modeling results further proved that ET distributions from the upper and lower soil and water table, while incorporating field-scale variability of soil and land cover properties, can be predicted reasonably well using IHM model.     

Independent integration practice on revamping 4200/3500 mm medium and heavy plate rolling mill of Bayi Steel in terms of process and make-up equipment

This study systematically reviews and summarizes relocation and revamping project of medium and heavy plate rolling mill in Bayi Steel.After detailed analysis was made on the main deficiency and problems of the original production line of Pudong Steel,systematical integration and improvement for the process and equipment were carried out accordingly.Through innovative practice of integration,Baosteel Engineering has greatly improved the technical process and equipment make-up,as well as the grades and quality of the products.The original man-operating line is redesigned into an automatic system controlled by Level 2 computer,reaching the advanced technical level of home-made medium and heavy plate production line in recent years.The project is constructed in two phases;The original product mix of Pudong Steel is maintained as much as possible in Phase I.After 3 500 mm single stand finishing mill is put into operation, capacity of hot- rolling medium and heavy plate reaches 650 000 t/a,with the maximum thickness at 40 mm.Equipment or facilities are reserved for production of pipeline steel and other grades.Pipeline steel, vessel plate,wind power plate and other TMCP and heat treatment products are projected in PhaseⅡ.After 4 200 mm roughing mill and its matched facilities are put into operation,capacity of hot-rolling medium and heavy plate will reach 120 000 t/a,with the maximum thickness at 80 mm.Through the optimization of process equipment and its function,the relocated medium and heavy plate mill production line has reached advanced level among similar domestic mills.The prominent achievements of the project are the revamping of thickness control system of the finishing mill and the newly installed shape control system.Automation control of the whole line is realized.     

Improvements in Frost Heave Laboratory Testing of Fine-Grained Soils

We present a laboratory system designed for studying frost heave in fine-grained soil. The system consists of: a modified refrigerator, a frost heave test cell, a laser for measuring heave, a differential pressure transducer for measuring water intake, and platinum resistance temperature detectors for measuring pedestal temperatures. The frost heave cell allows for visual observation of the sample, and accommodates pretest sample consolidation, freezing tests using a variety of freezing methods, triaxial tests on frozen soil, and thaw consolidation tests. The modified refrigerator maintains the specified temperature ±0.5°C during the full length of the test. Test results indicate repeatability of frost heave ratios ξ to within ±7%, and average heave rates to within ±0.05?mm/h. Results from frost heave tests conducted on five fine-grained soils indicate that: (1) a soil removed of its colloidal organic content becomes less frost susceptible; (2) the geomorphologic history of a “regional” soil is a critical factor influencing its frost susceptibility; and (3) ξ is dependent on overall clay content and is most sensitive to chlorite content.     

Field Measurements of Yazoo Clay Reveal Expansive Soil Design Issues

Field measurements of foundation movements in central Mississippi have revealed design issues involving expansive soils. At one building, field measurements of the first floor slab at 14 locations show that heaving occurred at a steady rate during part of an extensive drought. The steady rate was maintained throughout the final 21.5 months of a 23.5-month study period following a record drought that occurred at the beginning of the study. The average change in the movement rate was 2.9 mm (0.11 in.) per year over the last 21.5 months. Median movement rates for all the pins varied from 25 mm (0.98 in.) per year to 1.8 mm (0.07 in.) per year excluding the measurements made during the first part of the drought. Elevation surveys at another facility show how the rate of heave is influenced by geologic variations. These surveys also show how the depth of clay (from the surface) influenced heave and how differential movements of a structure are produced from these variations in geology. Design procedures for kind of movement are discussed.     

Modeling Enhanced In Situ Denitrification in Groundwater

A two-dimensional numerical solute transport model was developed for simulating an enhanced in situ denitrification experiment performed in a nitrate-contaminated aquifer on Cape Cod, Massachusetts. In this experiment, formate (HCOO?) was injected for a period of 26 days into the carbon-limited aquifer to stimulate denitrification. Calibration of the vertical-profile site model was demonstrated through error analysis and comparison with formate, nitrate, and nitrite concentration data monitored along a transect of three multilevel groundwater sampling wells for 75 days after initial injection. Formate utilization rates were approximately 142 and 38 μM/day for nitrate and nitrite reduction, respectively. Nitrate and nitrite utilization rates were approximately 29 and 8 μM/day, respectively. Nitrate utilization rates under enhanced conditions were 1 order of magnitude greater than previously reported naturally occurring rates. The nitrite production rate was approximately 29 μM/day. Persistence of nitrite was attributed to a combination of factors, including electron donor (formate) limitation late in the experiment, preferential utilization of nitrate as an electron acceptor, and greater nitrite production relative to nitrite utilization.     

Further clinical studies of curdlan sulfate (CRDS)--an anti-HIV agent

Curdlan sulfate (CRDS) is a semi-synthetic sulfated polysaccharide which inhibits the attachment of HIV to T-cells, and also has intracellular anti-HIV activity. In Phase I clinical trials, CRDS was found in 4 hr i.v. infusions, to be well tolerated up to 200 mg/70 kg and unexpectedly to produce marked, dose-related increases in CD4 lymphocytes in HIV-infected patients. Prolongation of bleeding time is expected to be the dose limiting toxicity, but no episodes of bleeding were seen. In one of the studies in this report, CRDS was administered i.v. daily for 7 days to HIV patients at doses of 40, 100, 140 and 180 mg/70 kg/day. At the higher doses, marked increases in CD4 and CD8 lymphocytes were observed. These increases mainly returned to baseline after 24 hr. To further delineate the pharmacokinetics of these changes in CD4 and CD8 lymphocytes, another Phase I study was done in which CRDS was infused i.v. over a 30 min period in HIV patients at single doses of 25, 50, 75, 100, 125, 150, 175 and 200 mg/70 kg/day. The drug was well tolerated in all cases and marked increases in CD4 lymphocytes were again seen at the higher doses, in some cases amounting to increases of 500 cells/mm3 after a single dose. The half-life of CRDS in man was found to be about two hours, as measured by activated partial thromboplastin time (APTT) and by plasma assays.     

Air-cooling of direct-coupled ultrasound applicators for interstitial hyperthermia and thermal coagulation

The feasibility of using air-cooling to improve the thermal penetration of direct-coupled interstitial ultrasound (US) applicators was investigated using biothermal simulations, bench experiments, phantom testing, and in vivo thermal dosimetry. Two applicator configurations using tubular US transducers were constructed and tested. The first design, intended for simultaneous thermobrachy-therapy, utilizes a 2.5 mm OD transducer with a central lumen to accommodate a radiation source from remote afterloaders. The second applicator consists of a 2.2 mm OD transducer designed for coagulative thermal therapy. Both designs provide cooling of the inner transducer surface by the counterflow of chilled air or CO2 gas through the annulus of the enclosed applicator. The average convective heat transfer (ha) associated with each applicator was determined empirically from curve-fits of radial steady-state temperatures measured in a tissue-mimicking phantom. High levels of convective heat transfer (ha > 500 W m-2 degrees C-1) were demonstrated in both designs at relatively low flow rates (< 5 L min-1). Transient and steady-state radial heating profiles were also measured in vivo (pig thigh muscle) with and without cooling. The therapeutic radius for hyperthermia (41-45 degrees C) was extended from 5-6 mm (without cooling) to 11-19 mm with air-cooling (4.8 L min-1, airflow 10 degrees C), effectively doubling and tripling the thermal penetration in vivo. Similar improvements were demonstrated at higher temperatures with the thermal coagulation applicator. Biothermal simulations, which modeled the physical, thermal, and acoustic parameters of the air-cooled applicator and surrounding tissue, were also used to investigate potential improvements in heating patterns. The simulated radial heating profiles with transducer cooling demonstrated significantly enhanced thermal penetration over the experimental range of convective transfer, and also agreed with in vivo results. These theoretical and experimental results clearly show air-cooling controls the transducer surface temperature, significantly increases thermal penetration, and produces a greater treatment volume for direct-coupled US applicators in hyperthermia and thermal coagulation.     

Below-Ground Performance of Rigid Polystyrene Foam Insulation: Review of Effective Thermal Resistivity Values Used in ASCE Standard 32-01—Design and Construction of Frost-Protected Shallow Foundations

Effective (design) thermal resistivity values for use of rigid, cellular polystyrene foam insulation in below-ground frost-protection applications play an important role in the success of the ASCE 32-01 standard. The ASCE 32-01 standard is currently recognized in U.S. model building codes as a cost-effective means of protecting building foundations against frost heave in regions with seasonal ground freezing and no permafrost. The long-term thermal performance of foundation insulation used for this purpose is, therefore, a critical building performance concern. This same concern also has relevance to sustained performance of below-ground insulation used for energy conservation purposes. This paper provides a critical review and analysis of data reported in the literature on below-ground thermal performance of rigid, cellular polystyrene foam insulations. These products can be molded expanded polystyrene or extruded polystyrene as defined by ASTM C578 in ASTM 2008 Standard. The findings serve to document and confirm effective thermal resistivity values originally incorporated into the ASCE 32-01 standard for frost protection of building foundations.     

Surface Heave Mechanisms in Horizontal Directional Drilling

Damage resulting from directionally drilled crossings has become a concern for municipalities and contractors due to the increased popularity of this trenchless installation method. Surface heave is one mechanism through which directionally drilled installations may damage existing surface structures such as pavements and foundations. Several factors contribute to the development of surface heave including backream rate, borehole pressure, downhole tooling, depth of cover, annular space size, and geotechnical properties. This paper presents and discusses results of a detailed field experiment which monitored surface heave under various installation characteristics. Four borepaths were designed to implement a full factorial examination to determine the interaction of backream rate, depth of cover, drill mud flow, and reamer type have on the development of surface heave. With greater understanding of how drilling practices affect the development of surface heave, practitioners of this technology may better plan installations to minimize the impact of their operation.