Initial Freezing Research Articles

Effect of cryopreservation protocol on postthaw characteristics of stallion sperm

Three ejaculates from each of eight stallions were subjected to cryopreservation in a milk/egg yolk-based freezing extender or an egg yolk-based freezing extender. Semen was exposed to a fast prefreeze cooling rate (FAST; semen immediately subjected to cryopreservation) or a slow prefreeze cooling rate (SLOW; semen pre-cooled at a controlled rate for 80 min prior to cryopreservation). Postthaw semen was diluted in initial freezing medium (FM) or INRA 96 (IMV Technologies, L'Aigle, France) prior to analysis of 10 experimental end points: total motility (MOT; %), progressive motility (PMOT; %), curvilinear velocity (VCL; μm/s), linearity (LIN; %), intact acrosomal and plasma membranes (AIMI; %), intact acrosomal membranes (AI; %), intact plasma membranes (MI; %), and DNA quality. Eight of 10 experimental endpoints (MOT, PMOT, average-path velocity [VAP], mean straight-line velocity [VSL], LIN AIMI, AI, and MI) were affected by extender type, with egg yolk-based extender yielding higher values than milk/egg yolk-based extender (P < 0.05). Exposure of extended semen to a slow prefreeze cooling period resulted in increased values for six of eight endpoints (MOT, PMOT, VCL, AIMI, AI, and MI), as compared with a fast prefreeze cooling period (P < 0.05). As a postthaw diluent, INRA 96 yielded higher mean values than FM for MOT, PMOT, VCL, average-path velocity, and mean straight-line velocity (P < 0.05). Treatment group FM yielded slightly higher values than INRA 96 for LIN and MI (P < 0.05). In conclusion, a slow prefreeze cooling rate was superior to a fast prefreeze cooling rate, regardless of freezing extender used, and INRA 96 served as a satisfactory postthaw diluent prior to semen analysis.

NMR and DSC Water Study During Osmotic Dehydration of Actinidia deliciosa and Actinidia chinensis Kiwifruit

This study investigated mass transfer and water state changes promoted by osmotic dehydration on two kiwifruit species, Actinidia deliciosa and Actinidia chinensis. Osmotic treatment was performed in a 61.5% w/v sucrose solution at three different temperatures (25, 35 and 45 °C), with treatment time from 0 to 300 min. Treatment time positively influenced kiwifruit water loss and solid gain while temperature significantly affected only water loss. Peleg’s model highlighted that the main response differences between the two species occurred during the initial phase of the osmotic treatment. Thermal properties and relaxation time measurements offered a complementary view concerning the effects of osmotic dehydration on kiwifruit. DSC parameters appeared to be sensitive to water and solid exchange between fruit and osmotic solution. LF-NMR proton T2 revealed the consequences of the water–solid exchange on the cell compartments, namely vacuole, cytoplasm plus extracellular space and cell wall. During the osmotic treatment, the initial freezing temperature and the freezable water content decrease was dependent on time and treatment temperature, showing a similar tendency for both the kiwifruit species. They evidenced the same treatment response also concerning the reduction of vacuole and the increase of cytoplasm plus extracellular space T2 values.

Numerical simulation on freezing phase change heat transfer in cryosurgery with two cryoprobes

AbstractA mathematical model for phase change heat transfer in biological tissue (including tumor and normal tissue) embedded with two cryoprobes was established. In this model, the vascular architecture was described as a tree‐like branched fractal network, and the effective thermal conductivity and flow rate of blood were presented based on this fractal structure. Occurrence of three regions including frozen, phase‐changing, and unfrozen regions in biological tissue during the freezing process was also considered. The numerical studies on temperature distribution and ice crystal growth process in biological tissue embedded with two cryoprobes were performed. The results showed that the growth rate of ice crystal is more rapid in the initial freezing stage and becomes slower later. So it is unreasonable to prolong freezing time merely without other assisting measures for enlarging the freezing region in the late freezing stage. Furthermore, the placement distance of the two cryoprobes plays a significant role in the growth of ice crystal in the initial freezing stage, and the influence of different distances between two probes on ice crystal growth becomes less profound with an increasing of freezing time. © 2011 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/htj.20332

Two-way avoidance acquisition is negatively related to conditioned freezing and positively associated with startle reactions: A dissection of anxiety and fear in genetically heterogeneous rats

The double, fear-driven "passive avoidance/active avoidance" conflict appearing during acquisition of two-way active avoidance, involves high levels of anxiety and a dominant tendency for freezing responses, which in turn run against the appearance of active escape/avoidance behavior. In the present study, by using a large sample genetically heterogeneous (N/Nih-HS) rats, we have tested the hypothesis that rats showing relatively higher levels of context-conditioned freezing (during the initial trials of that task) should show lower efficiency to acquire two-way avoidance behavior, i.e. the prediction that the initial context-conditioned freezing in the shuttle box would be negatively related to avoidance acquisition efficiency. In agreement with such a hypothesis, the results from the three rat subsamples used show that context-conditioned freezing (during the first 5 inter-trial intervals of the 40-trial two-way avoidance session) is negatively correlated (r=-0.34 to r=-0.64, p<0.001) with two-way avoidance acquisition, in a way that subgroups of rats with extremely high or low levels of freezing markedly differ in their avoidance performance: "high freezer" rats show much worse avoidance acquisition than "low freezers". Moreover, the relationships of conditioned freezing and avoidance acquisition with baseline and fear-potentiated startle, as well as with unconditioned anxiety (in the elevated zero-maze test), have also been studied. Taken collectively, the results indicate that: (i) context conditioned freezing is a reliable (and negative) predictor of two-way avoidance acquisition; (ii) baseline and fear-potentiated startle responses show positive associations with avoidance responding, and (iii) unconditioned anxiety in the elevated zero-maze is also negatively associated with two-way avoidance acquisition. Such patterns of associations are considered to be very informative in regard to the search for (common or differential) neural and genetic mechanisms of different forms of (unlearned or learned) anxious or fear responses.

Velocity and pattern of ice propagation and deep supercooling in woody stems of Castanea sativa, Morus nigra and Quercus robur measured by IDTA

Infrared differential thermal analysis (IDTA) was used to monitor the velocity and pattern of ice propagation and deep supercooling of xylem parenchyma cells (XPCs) during freezing of stems of Castanea sativa L., Morus nigra L. and Quercus robur L. that exhibit a macro- and ring-porous xylem. Measurements were conducted on the surface of cross- and longitudinal stem sections. During high-temperature freezing exotherms (HTEs; -2.8 to -9.4°C), initial freezing was mainly observed in the youngest year ring of the sapwood (94%), but occasionally elsewhere (older year rings: 4%; bark: 2%). Initially, ice propagated rapidly in the largest xylem conduits. This resulted in a distinct freezing pattern of concentric circles in C. sativa and M. nigra. During HTEs, supercooling of XPCs became visible in Q. robur stems, but not in the other species that have narrower pith rays. Intracellular freezing of supercooled XPCs of Q. robur became visible by IDTA during low-temperature freezing exotherms (<-17.4 °C). Infrared differential thermal analysis revealed the progress and the two-dimensional pattern of XPC freezing. XPCs did not freeze at once, but rather small cell groups appeared to freeze at random anywhere in the xylem. By IDTA, ice propagation and deep supercooling in stems can be monitored at meaningful spatial and temporal resolutions.

AVALIAÇÃO DA ESTABILIDADE DE SOLUÇÕES MODELO (CMC-SACAROSE) EM RECONGELAMENTOS

O objetivo deste trabalho foi avaliar a estabilidade de soluções modelo pela determinação da temperatura de início de congelamento depois de repetidos processos de congelamento. As soluções utilizadas eram compostas por água, sacarose e Carboxi-Metil-Celulose (CMC). Foram avaliadas as concentrações de sacarose de 15 e 31,1% (m/m total da amostra) e do espessante de 0,5, 1 e 1,5% (m/m total da amostra). Buscou-se determinar a possibilidade de reutilização de soluções modelo em ensaios de congelamento. Com os resultados obtidos pode-se concluir que para a concentração de espessante de 0,5% não houve alteração da capacidade de retenção de água. A variação da concentração de sacarose não influenciou a estabilidade das soluções durante o estudo.

Effect of Sulfate Contaminant on Soil Properties and Infrastructure Safety in Permafrost Regions

Contamination of unfrozen water in frozen soil could have adverse effects on surrounding infrastructure such as foundation instability or deterioration of trafficability. This paper describes the results of the experimental examination of the physical properties and mechanical behavior of Na2SO4 contaminated soil. Initial freezing temperature test, unfrozen water content test and unconfined compression tests were conducted on silts with 3 levels of concentrations (6, 18 and 42 ppt) of Na2SO4 and nonsaline cases at temperatures ranging between 0°C and -20°C. The test results indicate that the presence of salt significantly affect the physical properties and mechanical behavior of the frozen soil. Contamination of soils will cause depression of freezing temperature and degradation of permafrost. The freezing temperature depression ratio of Na2SO4 contaminated soil is 0.028°C/ppt. The unfrozen water content increases with an increase in salinity and temperature. The strength decreases with an increase in salinity, and the strength loss ratio of Na2SO4 contaminated soil is among 0.02-0.04MPa/ppt. Combined the effect of salinity and temperature on the strength, the decrease in strength with increase in unfrozen water content follows an exponential relationship. So estimation of salt concentration in the soil, and predictions of future increases of salt in the soil, is essential for design of buildings and roadways in permafrost.

Preparation of porous microcrystalline cellulose pellets by freeze‐drying: Effects of wetting liquid and initial freezing conditions

The effects of wetting liquid and initial freezing conditions on the pore volume and pore size distribution of freeze‐dried microcrystalline cellulose (MCC) pellets were studied with mercury porosimetry. Freeze‐drying was applied after extrusion/spheronization using two wetting liquids (water and water–isopropanol) and three initial freezing conditions (−30, 80, and −197°C). Also, the effects of initial freezing were compared to those on pellets prepared with extraction of NaCl from Avicel®/NaCl pellets. Pellet porosity was found to increase with decreasing initial freezing temperature and the increase is greater for pellets made with water as wetting liquid. The mean pore diameter is greater for the extracted pellets, followed by nonextracted MCC pellets made with water and water–isopropanol. Also, the pore diameter is greater for freezing at −80°C comparatively to that at −30°C, while it is smaller for freezing at −197°C. Narrower and more symmetrical pore size distributions were obtained with water–isopropanol at −197°C. The higher porosity obtained with water alone and the smallest mean pore diameter and narrower distribution obtained with water–isopropanol may be due to the effects of H‐bonding between isopropanol and water molecules on the nucleation and growth of ice crystals during the initial freezing. © 2009 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 2104–2113, 2010

Efficient ligation and cloning of DNA fragments with 2-bp overhangs

Various methods of ligation are currently available and routinely used by molecular biologists, such as blunt end ligation, cohesive end (two and four overhangs), and ligation of Taq polymerase-derived products. However, there is no efficient method for the cloning of DNA fragments with 2-bp overhangs. We present a simple method for the efficient ligation of DNA fragments with 2-bp overhanging ends, ranging in size from 0.7 to 2.5 kbp. Our method involves the initial heating and flash freezing of the vector–insert DNA mix, and a subsequent unique ligation reaction. This method provides a new molecular biology tool for researchers.

Water Freezes Differently on Positively and Negatively Charged Surfaces of Pyroelectric Materials

Although ice melts and water freezes under equilibrium conditions at 0 degrees C, water can be supercooled under homogeneous conditions in a clean environment down to -40 degrees C without freezing. The influence of the electric field on the freezing temperature of supercooled water (electrofreezing) is of topical importance in the living and inanimate worlds. We report that positively charged surfaces of pyroelectric LiTaO3 crystals and SrTiO3 thin films promote ice nucleation, whereas the same surfaces when negatively charged reduce the freezing temperature. Accordingly, droplets of water cooled down on a negatively charged LiTaO3 surface and remaining liquid at -11 degrees C freeze immediately when this surface is heated to -8 degrees C, as a result of the replacement of the negative surface charge by a positive one. Furthermore, powder x-ray diffraction studies demonstrated that the freezing on the positively charged surface starts at the solid/water interface, whereas on a negatively charged surface, ice nucleation starts at the air/water interface.

Computed tomographic and cross-sectional anatomic characterization of myofascial compartments and soft tissue spaces in the manus in cadavers of dogs without forelimb disease

To characterize the computed tomographic (CT) and cross-sectional anatomic features of myofascial compartments and soft tissue spaces in the manus of cadavers of dogs without forelimb disease. 33 cadavers of adult medium- to large-breed dogs without forelimb disease. Forelimbs were removed from the cadavers within 4 hours after euthanasia or within 6 hours after thawing from initial freezing. Specimens were then frozen for variable periods and thawed for approximately 16 hours before use. Each manus of 60 forelimbs underwent CT before and after injection of a radiopaque, blue-staining contrast medium into locations where soft tissue spaces and myofascial compartments were predicted (on the basis of pilot study data [6 forelimbs]). Two veterinary radiologists reviewed CT images and recorded the presence or absence of a discrete space or compartment at each injection site. Each manus was subsequently dissected or sectioned transversely. Locations of blue-staining contrast medium accumulation were compared with locations of contrast enhancement in CT images. Anatomic structures within each soft tissue space or myofascial compartment were described. 13 soft tissue spaces and 5 myofascial compartments were identified in the manus. Three myofascial structures that were examined were determined not to be compartments. Knowledge of soft tissue spaces and myofascial compartments are used to map the likely spread of disease in the hands and feet of humans. Thus, understanding the locations and extent of similar structures in the canine manus may improve the effectiveness of surgical interventions in dogs with injury or inflammation of this region of the forelimb.

Modeling frost heave in freezing soils

A generalized model for secondary frost heave in freezing fine-grained soils is presented. The cryostatic suction effect, which causes an increase in upward water permeation, ice-lens growth during freezing, and, as a consequence, the increase of soil heave, is considered to be the main mechanism of moisture transfer. Although the model in this paper has a number of approaches in common with the model of Fowler and Krantz (1994) it differs in at least several important respects. We recognize the need to determine the distribution of the moisture within the frozen fringe by approximation of the experimental data for the equilibrium unfrozen water content. This distribution is the result of the complicated interaction between water, ice and the mineral skeleton during the freezing process. The generalization of the Clapeyron relation, which is used in the work cited above, only estimates the drop in initial freezing temperature and does not define the connection with the external temperature gradient ∇T, which is responsible for the frost heave process. This very important aspect is discussed in detail in the Introduction to our paper. Another difference is the fact that our solution is based on a dimensionless system of equations. We take into account the ratio Pe/Ste ≠ 1 (where Pe << 1). This approach allows us to obtain both a more general solution as well as analyze frost heave and propagation of the freezing front as they depend upon the convective (Pe) and phase transition (Ste) characteristics (criteria) of the process. The theoretical results derived from our solution of the analysis for fine-grained soils are compared, in good agreement, with experimental investigations and numerical models. A singularity of the solution at the initial point in time is discussed. In this respect the asymptotic solution for short and long times is obtained. The results are compared with both solutions (modeling and asymptotic). The model presented predicts the frost heave and freezing processes in porous media with reasonable accuracy and satisfactorily reflects observed phenomena, and thus can be suitable for engineering practice.

Combinatory Models for Predicting the Effective Thermal Conductivity of Frozen and Unfrozen Food Materials

A model to predict the effective thermal conductivity of heterogeneous materials is proposed based on unit cell approach. The model is combined with four fundamental effective thermal conductivity models (Parallel, Series, Maxwell-Eucken-I, and Maxwell-Eucken-II) to evolve a unifying equation for the estimation of effective thermal conductivity of porous and nonporous food materials. The effect of volume fraction (ν) on the structure composition factor (ψ) of the food materials is studied. The models are compared with the experimental data of various foods at the initial freezing temperature. The effective thermal conductivity estimated by the Maxwell-Eucken-I + Present model shows good agreement with the experimental data with a minimum average deviation of ±8.66% and maximum deviation of ±42.76% of Series + Present Model. The combined models have advantages over other empirical and semiempirical models.

Use of Average Molecular Weights for Product Categories to Predict Freezing Characteristics of Foods

In the design of food freezing process, food property parameters, initial freezing temperature (T(Fi)), and frozen water fraction (X(I)) are required. The predictive approaches of these 2 parameters have been developed based on mass fractions and molecular weights of specific food components such as proteins, carbohydrates, minerals, and acids/bases. In this study, the molecular weights of the key mineral and acid/base components were successfully represented using average molecular weights (M) and 4 T(Fi) and X(I) calculation approaches were proposed. Based on an analysis of 212 food products, the absolute differences (AD) between the experimental and predicted T(Fi) values for the 4 approaches were small. The prediction for the food model category was excellent with average AD values as low as +/- 0.03 degrees C. For the other food categories, the prediction efficiency was impressive with values between +/- 0.22 and +/- 0.38 degrees C. The predicted relationship between temperature and X(I) for all analyzed food products provided close agreements with experimental data.

Experimental investigation of ice slurry heat transfer in horizontal tube

Heat transfer of ice slurry flow based on ethanol–water mixture in a circular horizontal tube has been experimentally investigated. The secondary fluid was prepared by mixing ethanol and water to obtain initial alcohol concentration of 10.3% (initial freezing temperature -4.4 °C). The heat transfer tests were conducted to cover laminar and slightly turbulent flow with ice mass fraction varying from 0% to 22% depending on test performed. Measured heat transfer coefficients of ice slurry are found to be higher than those for single phase fluid, especially for laminar flow conditions and high ice mass fractions where the heat transfer is increased with a factor 2 in comparison to the single phase flow. In addition, experimentally determined heat transfer coefficients of ice slurry flow were compared to the analytical results, based on the correlation by Sieder and Tate for laminar single phase regime, by Dittus–Boelter for turbulent single phase regime and empirical correlation by Christensen and Kauffeld derived for laminar/turbulent ice slurry flow in circular horizontal tubes. It was found that the classical correlation proposed by Sieder and Tate for laminar forced convection in smooth straight circular ducts cannot be used for heat transfer prediction of ice slurry flow since it strongly underestimates measured values, while, for the turbulent flow regime the simple Dittus–Boelter relation predicts the heat transfer coefficient of ice slurry flow with high accuracy but only up to an ice mass fraction of 10% and Re cf > 2300 regardless of imposed heat flux. For higher ice mass fractions and regardless of the flow regime, the correlation proposed by Christensen and Kauffeld gives good agreement with experimental results.

Comparison of FASST and SNTHERM in Three Snow Accumulation Regimes

AbstractNumerical experiments of snow accumulation and depletion were carried out as well as surface energy fluxes over four Cold Land Processes Experiment (CLPX) sites in Colorado using the Snow Thermal model (SNTHERM) and the Fast All-Season Soil Strength model (FASST). SNTHERM is a multilayer snow model developed to describe changes in snow properties as a function of depth and time, using a one-dimensional mass and energy balance. The model is intended for seasonal snow covers and addresses conditions found throughout the winter, from initial ground freezing in the fall to snow ablation in the spring. It has been used by many researchers over a variety of terrains. FASST is a newly developed one-dimensional dynamic state-of-the-ground model. It calculates the ground’s moisture content, ice content, temperature, and freeze–thaw profiles as well as soil strength and surface ice and snow accumulation/depletion. Because FASST is newer and not as well known, the authors wanted to determine its use as a snow model by comparing it with SNTHERM, one of the most established snow models available. It is demonstrated that even though FASST is only a single-layer snow model, the RMSE snow depth compared very favorably against SNTHERM, often performing better during the accumulation phase. The surface energy fluxes calculated by the two models were also compared and were found to be similar.

Experimental investigation of ice slurry flow pressure drop in horizontal tubes

Pressure drop behaviour of ice slurry based on ethanol–water mixture in circular horizontal tubes has been experimentally investigated. The secondary fluid was prepared by mixing ethyl alcohol and water to obtain initial alcohol concentration of 10.3% (initial freezing temperature −4.4 °C). The pressure drop tests were conducted to cover laminar and slightly turbulent flow with ice mass fraction varying from 0% to 30% depending on test conditions. Results from flow tests reveal much higher pressure drop for higher ice concentrations and higher velocities in comparison to the single phase flow. However for ice concentrations of 15% and higher, certain velocity exists at which ice slurry pressure drop is same or even lower than for single phase flow. It seems that higher ice concentration delay flow pattern transition moment (from laminar to turbulent) toward higher velocities. In addition experimental results for pressure drop were compared to the analytical results, based on Poiseulle and Buckingham–Reiner models for laminar flow, Blasius, Darby and Melson, Dodge and Metzner, Steffe and Tomita for turbulent region and general correlation of Kitanovski which is valid for both flow regimes. For laminar flow and low buoyancy numbers Buckingham–Reiner method gives good agreement with experimental results while for turbulent flow best fit is provided with Dodge–Metzner and Tomita methods. Furthermore, for transport purposes it has been shown that ice mass fraction of 20% offers best ratio of ice slurry transport capability and required pumping power.

Current pulse measurement of capacitance during molten salt electrochemical experiments

In earlier work in our laboratories, a current pulse method was developed that allows in situ (dynamic) measurements of electrode capacitance. The present work describes the successful application of the technique to the study of electrode properties in molten salt electrolytes. As expected, the electrode capacitance increases as the electrode surface area exposed to a molten salt bath increases. Furthermore, creep of the bath along the surface of a conductive ceramic anode and subsequent ingress into the anode pores is observed as an increase in capacitance. The pulse technique also gives an indication of phase changes that occur during the reduction of a solid titanium dioxide cathode and a highly sensitive measure of the temperature at which initial freezing of the calcium chloride electrolyte begins. These observations provide useful in situ information about changes in electrode properties in molten salt electrolytes that are difficult to obtain from other techniques.

An assessment of the effects of sample ischaemia and spinning time on the metabolic profile of brain tumour biopsy specimens as determined by high‐resolution magic angle spinning 1H NMR

High-resolution magic angle spinning (HRMAS) (1)H NMR of biopsy tissue provides a biochemical profile that has potential diagnostic and prognostic value, and can aid interpretation of the lower-resolution (1)H-NMR spectra obtained in vivo. However, the biochemical profile obtained may be affected by experimental factors such as a period of ischaemia before snap-freezing of the biopsy tissue for subsequent analysis and the mechanical stress of the spinning procedure of HRMAS itself. We have used normal rat brain cortex as a 'gold standard', either funnel-frozen or deliberately allowed to become ischaemic for set periods of time before snap-freezing, to quantitatively investigate these two effects. In addition, we have compared biochemical changes that occur in normal rat brain during HRMAS (spun continuously at 5 kHz for 4 h at 4 degrees C as could be required for a two-dimensional acquisition) with those that occur in biopsy samples from low-grade and high-grade adult human astrocytomas, during the same HRMAS procedure. Significant changes due to delayed initial sample freezing were noted in metabolites associated with glycolysis (alanine, glucose and lactate), as expected. However, for the funnel-frozen rat tissue at 4 degrees C, there were even more significant changes, which appear to be the result of extended spinning at 5 kHz. In particular, the 18% total creatine increase observed is unlikely to be de novo synthesis of creatine. More likely, the asymptotic exponential increase in creatine suggests an exponential release of an NMR-invisible bound creatine store as a result of tissue damage from mechanical stress of sample spinning. Overall, it appears that tissue ischaemia during biopsy excision and delays in snap-freezing may have less significant effects on metabolite profile than the prolonged spinning times required for two-dimensional HRMAS, and this must be accounted for when results are being interpreted.

Studies on Construction Pre-control of a Connection Aisle Between Two Neighbouring Tunnels in Shanghai by Means of 3D FEM, Neural Networks and Fuzzy Logic

The ground freezing construction technique is one of the most effective and widely applied site construction methods in soft soil areas, like Shanghai. Some elevation-inclined refrigeration pipes are arranged for the artificial freezing excavation of the Pudong-side first-storey connection aisle, which is designed to connect two adjacent tunnel lanes of Shanghai East-Fuxing-Road tunnel project. No advanced research results could be found for computing the temperature field of tunnels and aisles frozen with inclined refrigeration pipes. Anyhow the computation of the relevant temperature field is of high importance for the safe and economical excavation of the above-mentioned aisle. In this paper, a method for computing the aisle temperature field using 3D FEM is given, and the computation accuracy is verified by contrasting the computed and site measured results. The back propagation neural networks are also applied to the temperature prediction using self-developed Neural Network-Expert System software, the predicted results are also very satisfactory. The mechanism during freezing and aisle excavation will be discussed on the basis of 3D FEM simulation. The authors believe that studying the parameter-sensitivity of temperature field is very important for the optimum selection of parameter values. So, in this paper, the parameter-sensitivity of temperature field is also discussed. In order to obtain the optimum frozen wall thickness, the relation between the frozen wall thickness and the initial freezing brine temperature is studied. At the end, an excavation pre-control plan is proposed by means of fuzzy logic theory for improving the excavation safety. The research result of the current paper is very helpful for projects that will be excavated by freezing construction technique.