Due to the lack of living space and the increase in population, there has been a construction boom in the underground space to improve the quality of human life. Tunnel engineering plays a vital role in the development of underground space. In addition to traditional methods, some intelligent methods such as artificial neural networks (ANNs) have been applied to various problems in the tunnel domain in recent years. This paper systematically reviews the application of ANNs from different aspects of tunnel engineering. It reveals that the backpropagation algorithm (BPA) and Levenberg-Marquardt algorithm (LMA) are the most widely used. Due to the limitations of some original models, some scholars use optimization algorithms such as particle swarm optimization (PSO) and genetic algorithm (GA) to optimize the original ANNs to obtain better prediction results. A comparison between the ANN-based methods and methods like statistical methods is conducted. Finally, the following conclusions can be drawn: (1) The recommended ratio of the training set and test set is 3:1; (2) The advantage of optimized ANNs is not apparent when the optimization algorithm varies. Additionally, the performance of ANNs is always better than that of statistical methods.

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Escherichia coli O157:H7 survived longer in soils from plastic-greenhouse cultivation than soils from the open field. Soil pH, organic carbon levels, and the ratio of bacterial phospholipid fatty acids (PLFAs) to fungal PLFAs played the significant roles in survival of O157:H7. Greater attention should be paid to the control of pathogen contamination under conditions of plasticgreenhouse cultivation. E scherichia coli O157:H7 is dangerous because of its resistance to low pH (2.5), its low infective dose (as few as 10 cells), and its high pathogenicity (1). Raw fruits and vegetables, especially leafy greens that are consumed raw, are well-known vehicles for transmitting O157:H7 and may be polluted via field application of raw manure or contaminated irrigation water (2, 3). O157:H7 survival in soils from vegetable field should be considered an important factor for the likelihood of vegetable contamination. In China, plastic-greenhouse cultivation of vegetables is becoming more popular because of the higher growth rate and yield. However, little is known about the effects of various soil cultivation practices on the survival of O157:H7. The aim of this study was therefore to assess its survival in soils from a vegetable field under conditions of different cultivation patterns.Five soils (S0, S1, S4, S7, and S15) were collected from a depth of 0 to 20 cm in fields (sites) that were under conditions of various lengths of time (0, 1, 4, 7, and 15 years, respectively) of plasticgreenhouse cultivation in the same area. Three replicates were sampled for each site. The selected soil properties are listed in Table 1. O157:H7 cells were inoculated into the soil samples and gently mixed to establish a cell density of about 10 6 CFU per gram of dry weight (CFU · g Ϫ1 ). Forty grams (measured on the basis of analysis of oven-dried samples) of inoculated soil was placed in a 50-ml sterile plastic tube. All tubes (triplicates for each site, plus uninoculated controls) were incubated in the dark at 25 Ϯ 1°C with the field capacity (soil water content) at Ϫ33 kPa. Sterile deionized water was added to the tubes every 2 days to maintain constant soil moisture status during the incubation. A soil subsample was taken from each tube at 0, 0.04, 1, 3, 5, 7, 10, 15, and 25 days after inoculation and subjected to 10-fold serial dilutions with 0.1% peptone buffer. The last three of the serial dilutions per sample were plated onto sorbitol SMAC-BCIG (sorbitol MacConkey-5-bromo-4-chloro-3-indoxyl-␤-D-glucuronide) agar containing 100 g · ml Ϫ1 of rifampin and 25 g · ml Ϫ1 of nalidixic acid for enumeration (37°C, 16 h). The sampling was stopped after O157:H7 cells below the detection limit (approximately 100 CFU · g Ϫ1 ) appeared twice in succession during the incubation. Survival of O157:H7 was modeled by fitting the experimental data to the Weibull survival function proposed by Mafart et al. (4). The time needed to reach the detection limit (t d ) was calculated from the Weibull survival function.Enumeration analysis indicated that there wa...

Laboratory studies on Escherichia coli O157:H7 survival in soils from four different land use types: forest, tea plantation, bamboo grove, and vegetable garden were investigated at 25 ± 1 °C with the field capacity (soil water content at -33 kPa). Results showed that E. coli O157:H7 declined quickly in the test soils, but its survival dynamics varied in the soils under different land use types. The survival time needed to reach the detection limit (t d) in the test soils ranged from 2.1 to 3.6 days, with slightly longer t d values being observed in soils from the bamboo grove. Stepwise multiple regression analysis revealed that the t d values were shorter in sandy, lower pH, and lower organic carbon content soils. Different E. coli O157:H7 survival time in the soils under different land uses suggests that it is important to adapt proper management practices for reducing the potential risks of pathogen contamination when diary manure is applied to agricultural land.

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By selecting the ratio of the cumulative maximum deformation of the retaining structure to the excavation depth as the control parameter of the retaining structure deformation, this paper established a sidewall unloading model which can consider the deformation of the retaining structure and the spatial effect of foundation pit excavation. Meanwhile, the impact region of the sidewall was divided to calculate the distribution of additional stress caused by foundation pit excavation. On this basis, through introducing the collaborative deformation model for rotation and dislocation of a shield tunnel, this paper studied the longitudinal deformation of the adjacent shield tunnel due to foundation pit excavation. Moreover, several engineering cases were given to verify the reliability of the proposed method, and the influencing factors were analyzed. The following conclusions were obtained: the axial horizontal displacement of the shield tunnel by the side of the foundation pit was normally distributed, and the calculated value was in good agreement with the measured value; the longitudinal deformation of the shield tunnel was mainly induced by the unloading effect of the sidewall of the foundation pit, which was parallel and closed to the tunnel; the soil excavation in the vicinity of the buried depth of the tunnel would result in a significant increase in longitudinal deformation; with the increase in the retaining structure deformation of the foundation pit, the longitudinal deformation of the adjacent shield tunnel and its influence scope also increased; the longitudinal deformation of the shield tunnel decreased with the increase of clearances between the foundation pit and tunnel; and finally, the excavation of the foundation pit had a great influence on the shallowly buried shield tunnel nearby, and the effect of foundation pit excavation on the tunnel decreased with the increase of the burial depth of the shield tunnel.

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