The Evolution and Economic and Social Effects of the Spatial and Temporal Pattern of Transport Superiority Degree in Southern Xinjiang, China

Transportation significantly influences economically underdeveloped arid regions, impacting economic growth and social progress. Analyzing Transport Superiority Degree (TSD) and its implications in such regions is crucial. A new arid region-specific evaluation framework addresses traditional limitations by considering indicators like route connectivity and desert interference. This article conducts an empirical study using Southern Xinjiang as a research case. It combines comprehensive evaluation methods, spatial autocorrelation methods, spatial Durbin models, and coupling coordination models to depict Transport Support Capability (TSC), Transport Access Capacity (TAC), and Transport Guarantee Capacity (TGC) at different scales in Southern Xinjiang from 2000 to 2020. The study reveals spatial patterns, evolutionary characteristics, economic impacts, and social effects of TSD at various scales. Key findings include: (1) Rapid expansion of transportation infrastructure in Southern Xinjiang. The levels of TSD at different scales have gradually increased, and spatial and temporal pattern differences are evident. At the county level, TSD forms a “core-periphery” spatial pattern centered around the Southern Xinjiang Railway, with “high-high” agglomeration areas centered around Kashgar city and “low-low” agglomeration areas centered around Qiemo County. (2) Prefectural-level TSD improvements have limited impacts on regional development, while county-level TSC, TAC, TGC, and TSD positively affect economic and social growth but also exhibit competitive effects. (3) TSD is transitioning from non-coordinated to coordinated development with economic and social progress at different scales. This research informs transportation facility evaluation in arid regions

A study of the resonance characteristics of a staggered rock slope under the tri-dimension earthquake wave

The resonance induced by an earthquake often causes more serious damage to the slope and directly affects its seismic performance. To study the resonance characteristics of a staggered rock slope, a 3D numerical model of the slope is established by using the finite element software ANSYS, and the effect of staggered space on the natural frequency of the slope is analyzed. The resonance response laws of different locations on the slope surface and the effect of the earthquake frequency on the stress of the slope are discussed by the harmonic response analysis. The results show that (1) the larger the slope slip distance is, the smaller the fundamental frequency is, and the resonance phenomena may occur under different staggered distances. The horizontal resonance displacement of the slope surface is larger than the vertical one. The front slope has a larger peak displacement and lower resonant frequency compared with those of the back slope. (2) Both the low and high-order natural frequencies can be excited to cause resonance, but the displacement of the high-order resonance is relatively small. The horizontal displacement peak of the front slope and back slope is in the order: top > middle > foot, while that of the side slope is in the order: middle > top > foot. Under high-frequency loading, the dynamic response of the slope at the lower part may be greater than that at the upper part. (3) The shear failure of the slope toe is the main damage in slope resonance. The location of the maximum shear and tensile stress is related to the range of loading frequency. The front slope is more prone to damage. Ground motions with low frequency have a greater influence on the front slope, while high frequency ground motions have the opposite effect. The results can be used as reference to determine the key reinforcement position of a staggered slope in the seismic fortification

Theoretical Analysis on the Effectiveness of Pipe Roofs in Shallow Tunnels

When a pipe roof is used as a pre-support for the surrounding rock in a shallowly buried tunnel, accurate prediction of the support effectiveness of the pipe roof is important in order to ensure the rationality of the pipe roof structure design. Based on analysis of pipe roof pre-support effects, considering the construction time of pipe roof structures and the interaction mechanisms between the steel pipes of the pipe roof and the surrounding rock, we establish a calculation model of the surrounding rock pressure acting on each steel pipe of the pipe roof on the semi-circular pre-support boundary. Through comparison and analysis with the measured results, we demonstrate that the calculation model for surrounding rock pressure and the calculation model for stress and deformation of the pipe roof are reasonable. According to the deformation coordination conditions between the steel pipe of the pipe roof and the surrounding rock on the pre-support boundary and alongside the Peck formula, we establish a theoretical analysis method for pipe roof pre-support effectiveness based on the indexes of the ground loss rate, settlement trough width, and maximum ground surface settlement, thereby realizing a quantitative evaluation of pipe-roof pre-support effectiveness. At the same time, the effects of steel pipe diameter, circumferential spacing, and excavation footage length on the pre-support effectiveness of the pipe roof are analyzed. The conclusions can be used as a basis for the design and optimization of pipe roofs and as a guide for the application of pipe roofs

Modification of the Peck Formula for a Double-Track Shield Tunnel under Expressway Subgrade

In practice, asymmetric formation disturbance occurs due to the sequence of excavation though parallel double-track tunnel is a typical symmetrical engineering. Based on a shield tunneling project of a section of the Suzhou Rail Transit under the subgrade of the Shanghai–Nanjing Expressway, a finite element model was established to obtain a numerical solution that was validated by the measured data to guarantee reliability. According to the construction characteristics of the shield method, two correction coefficients—namely the soil loss rate correction coefficient α and the settlement trough width correction coefficient β—were introduced. A modified Peck formula suitable for the preceding tunnel and the subsequent tunnel was proposed. The applicability of the modified Peck formula was verified by another similar project. The results showed that the numerical solution can better reflect the actual settlement of the highway subgrade under shield tunneling. The results calculated by the classic Peck formula had a large error in comparison with the measured data. The modified empirical formula could more accurately predict the settlement of the expressway subgrade caused by the shield method when α1 = 0.38 and β1 = 2.08 for the preceding tunnel and α2 = 0.29 and β2 = 1.99 for the subsequent tunnel

Seismic Response Analysis of Uplift Terrain under Oblique Incidence of SV Waves

In order to analyze the impact of seismic waves on the venue earthquake, based on the display finite element method, the viscoelastic artificial boundary is used to analyze the variation of the ground motion amplification coefficient and the Fourier spectrum of the raised terrain under different incident angles with SV wave oblique incidence on different slopes. This verification model analysis solution and numerical solution are better. The numerical simulation results show that as the degree of the slope increases, the seismic amplification coefficient increases, and its slope amplification coefficient changes significantly. The X direction coefficient is greater than Y’s magnification coefficient. The Fourier curve with a frequency of 0.2~1 Hz increases with the slope of the raised terrain; when the El Centro is incorporated at 30°, the Fourier spectrum amplitude decreases as the incident angle increases in the low-frequency band. The amplitude of the Fourier spectrum at the high-frequency band monitoring point changes with the incident angle. In the high-frequency band from 1 to 10 Hz, the rate of amplitude change is the largest. When the incident angle is at 0°, the amplification coefficient in the Y direction is basically symmetric

Seismic Response Analysis of Uplift Terrain under Oblique Incidence of SV Waves

In order to analyze the impact of seismic waves on the venue earthquake, based on the display finite element method, the viscoelastic artificial boundary is used to analyze the variation of the ground motion amplification coefficient and the Fourier spectrum of the raised terrain under different incident angles with SV wave oblique incidence on different slopes. This verification model analysis solution and numerical solution are better. The numerical simulation results show that as the degree of the slope increases, the seismic amplification coefficient increases, and its slope amplification coefficient changes significantly. The X direction coefficient is greater than Y’s magnification coefficient. The Fourier curve with a frequency of 0.2~1 Hz increases with the slope of the raised terrain; when the El Centro is incorporated at 30°, the Fourier spectrum amplitude decreases as the incident angle increases in the low-frequency band. The amplitude of the Fourier spectrum at the high-frequency band monitoring point changes with the incident angle. In the high-frequency band from 1 to 10 Hz, the rate of amplitude change is the largest. When the incident angle is at 0°, the amplification coefficient in the Y direction is basically symmetric

Modification of the Peck Formula for a Double-Track Shield Tunnel under Expressway Subgrade

In practice, asymmetric formation disturbance occurs due to the sequence of excavation though parallel double-track tunnel is a typical symmetrical engineering. Based on a shield tunneling project of a section of the Suzhou Rail Transit under the subgrade of the Shanghai–Nanjing Expressway, a finite element model was established to obtain a numerical solution that was validated by the measured data to guarantee reliability. According to the construction characteristics of the shield method, two correction coefficients—namely the soil loss rate correction coefficient α and the settlement trough width correction coefficient β—were introduced. A modified Peck formula suitable for the preceding tunnel and the subsequent tunnel was proposed. The applicability of the modified Peck formula was verified by another similar project. The results showed that the numerical solution can better reflect the actual settlement of the highway subgrade under shield tunneling. The results calculated by the classic Peck formula had a large error in comparison with the measured data. The modified empirical formula could more accurately predict the settlement of the expressway subgrade caused by the shield method when α1 = 0.38 and β1 = 2.08 for the preceding tunnel and α2 = 0.29 and β2 = 1.99 for the subsequent tunnel

A clinical-radiomics combined model based on carotid atherosclerotic plaque for prediction of ischemic stroke

ObjectivesTo accurately predict the risk of ischemic stroke, we established a radiomics model of carotid atherosclerotic plaque-based high-resolution vessel wall magnetic resonance imaging (HR-VWMRI) and combined it with clinical indicators.Materials and methodsIn total, 127 patients were finally enrolled and randomly divided into training and test cohorts. HR-VWMRI three-dimensional T1-weighted imaging (T1WI) and contrast-enhanced T1WI (T1CE) were collected. A traditional model was built by recording and calculating radiographic features of the carotid plaques and patients’ clinical indicators. After extracting radiomics features from T1WI and T1CE images, the least absolute shrinkage and selection operator (LASSO) algorithm was used to select the optimal features and construct the radiomics_T1WI model and the radiomics_T1CE model. The traditional and radiomics features were used to build combined models. The performance of all the models predicting ischemic stroke was evaluated in the training and test cohorts, respectively.ResultsBody mass index (BMI) and intraplaque hemorrhage (IPH) were independently related to ischemic stroke and were used to build the traditional model, which achieved an area under the curve (AUC) of 0.79 versus 0.78 in the training and test cohorts, respectively. The AUC value of the radiomics_T1WI model is the lowest in the training and test cohorts, but the prediction performance is significantly improved when the model combines IPH and BMI. The AUC value of the combined_T1WI model was 0.78 and 0.81 in the training and test cohorts, respectively. In addition, in the training and test cohorts, the radiomics_T1CE model based on HR-VWMRI combined clinical characteristics, which is the combined_T1CE model, had the highest AUC value of 0.84 and 0.82, respectively.ConclusionCompared with other models, the radiomics_T1CE model based on HR-VWMRI combined clinical characteristics, which is a combined_T1CE model, can accurately predict the risk of ischemic stroke