Development of automatic prediction model for ground vibration using support vector machine

This study develops an automatic prediction model for ground vibration induced by Taiwan high-speed trains on embankments. Various field-measured ground vibration data comprise a database used for developing the prediction model. First, the main characteristics that affect the overall vibration level are established on the basis of measurement result database. These main influence factors include train speed, ground condition, measurement distance, and supported structure. A support vector machine (SVM) algorithm, which is a widely used classification model, is then adopted to predict the vibration level induced by high-speed trains on embankments. The measured and predicted vibration levels are compared to verify prediction model reliability. Analytical results show that the more the measured vibration data located in one vibration group is collected, the higher of the accuracy rate will be. Generally, the developed SVM model can reasonably predict ground vibration level in various frequency ranges. Prediction results are discussed in detail, and the methodology for developing the automatic ground vibration level prediction system is presented

Side Resistance of Drilled Shafts Socketed into Rocks for Serviceability and Ultimate Limit States

This study evaluates the analysis models of side resistance in rock sections by utilizing a wide variety of load test data. Available analytical models including the empirical adhesion factor versus the rock’s uniaxial compressive strength and its root are analyzed and compared statistically to determine the optimum relationships. The interpretation criteria for the L1 and L2 methods are used to analyze the load test results for serviceability and ultimate limit states, respectively. The analysis results show that the relationship model with the empirical adhesion factor versus the root of the rock’s uniaxial compressive strength exhibits better correlation than the one with the rock’s uniaxial compressive strength. Moreover, the general coordinate axes regression equation demonstrates better reliability than the semi-logarithmic and full logarithmic axes equations for both limit states. Based on these analyses, specific design recommendations for the side resistance of drilled shafts socketed into rocks are developed and provided with the appropriate statistics to verify their reliability

Establishment of ground vibration prediction model for high-speed trains on embankments

A series of field measurement data is used to establish the prediction model of ground vibration induced by Taiwan high-speed trains on embankments. These measurements consist of various possible influence factors, such as train speed, ground shear wave velocity, and structure volume. The characteristics of near-field ground vibration, far-field vibration propagation, and vibration influence distance are then evaluated from these measurement data. The analyses reveal that the near-field ground vibration level mainly depends on train speed and ground shear wave velocity. The influence of structure volume on the vibration level is minor. The far-field vibration propagation is affected by ground shear wave velocity. The analysis results also show that the attenuation coefficient is different for each frequency range. In general, the measured ground vibration in the high frequency range has the highest attenuation coefficient and that in the low frequency range has the lowest. For the vibration influence distance, the rock can propagate the vibration to the farthest distance among all soil types while the sand/silt/clay soils show the shortest. Finally, a specific ground vibration prediction model is established using these characteristics

Evaluation of tip capacity analysis model for drilled shafts in gravelly soils

This paper examines an analysis model for predicting the tip capacity of drilled shaft foundations under gravelly soils. Forty one static compression load test data are utilized for this purpose. Comparison of predicted and measured results demonstrates that the prediction model greatly overestimates the tip capacity of drilled shafts. Further assessment on the model reveals a greater variation in three coefficients, including the effective overburden pressure ( q ), the overburden bearing capacity factor ( q N ), and the bearing capacity modifier for soil rigidity ( qr ζ ). These factors are modified from the back-analysis of the drilled shaft load test results. Varying effective shaft depths are considered for the back-calculation to evaluate their effects on capacity behavior. Based on the analyses, the recommended effective shaft depth for the evaluation of effective overburden pressure is limited to 15B (B = shaft diameter). The q N and qr ζ are enhanced while maintaining their basic relationship with the soil effective friction angle ( ), φ in which the q N increases and qr ζ decreases as φ increases. Specific design recommendations for the tip bearing capacity analysis of drilled shafts in gravelly soils are given for engineering practice

Evaluation of tip capacity analysis model for drilled shafts in gravelly soils

This paper examines an analysis model for predicting the tip capacity of drilled shaft foundations under gravelly soils. Forty one static compression load test data are utilized for this purpose. Comparison of predicted and measured results demonstrates that the prediction model greatly overestimates the tip capacity of drilled shafts. Further assessment on the model reveals a greater variation in three coefficients, including the effective overburden pressure ( q ), the overburden bearing capacity factor ( q N ), and the bearing capacity modifier for soil rigidity ( qr ζ ). These factors are modified from the back-analysis of the drilled shaft load test results. Varying effective shaft depths are considered for the back-calculation to evaluate their effects on capacity behavior. Based on the analyses, the recommended effective shaft depth for the evaluation of effective overburden pressure is limited to 15B (B = shaft diameter). The q N and qr ζ are enhanced while maintaining their basic relationship with the soil effective friction angle ( ), φ in which the q N increases and qr ζ decreases as φ increases. Specific design recommendations for the tip bearing capacity analysis of drilled shafts in gravelly soils are given for engineering practice

Evaluation of tip capacity analysis model for drilled shafts in gravelly soils

This paper examines an analysis model for predicting the tip capacity of drilled shaft foundations under gravelly soils. Forty one static compression load test data are utilized for this purpose. Comparison of predicted and measured results demonstrates that the prediction model greatly overestimates the tip capacity of drilled shafts. Further assessment on the model reveals a greater variation in three coefficients, including the effective overburden pressure ( q ), the overburden bearing capacity factor ( q N ), and the bearing capacity modifier for soil rigidity ( qr ζ ). These factors are modified from the back-analysis of the drilled shaft load test results. Varying effective shaft depths are considered for the back-calculation to evaluate their effects on capacity behavior. Based on the analyses, the recommended effective shaft depth for the evaluation of effective overburden pressure is limited to 15B (B = shaft diameter). The q N and qr ζ are enhanced while maintaining their basic relationship with the soil effective friction angle ( ), φ in which the q N increases and qr ζ decreases as φ increases. Specific design recommendations for the tip bearing capacity analysis of drilled shafts in gravelly soils are given for engineering practice

Applicability of Various Load Test Interpretation Criteria in Measuring Driven Precast Concrete Pile Uplift Capacity

This paper presents a comprehensive analysis of load test interpretation criteria to determine their suitability to driven precast concrete (PC) pile uplift capacity.  A database was developed containing static pile load tests and utilized for the evaluation. The piles were round and square cross-sections under drained and undrained loading. To explore and compare their behavior, the stored data were categorized into four groups.  In general, the trends of every criterion for the four groups were notably the same. In both drained and undrained loading, slightly larger interpreted capacities were demonstrated by square piles than by round piles. Moreover, round piles demonstrated more ductile load-displacement response than square piles especially in undrained loading. Statistical analyses presented that smaller values of displacements exhibited higher coefficient of variation. The drained and undrained tests were compared and results showed less variability in drained than undrained loading and capacity ratios (Qx/QCHIN) in drained loading were slightly higher than in undrained loading. The interrelationship and applicability of these criteria as well as the design recommendations in terms of normalized capacity and displacement were given based on the analyses

Applicability of Various Load Test Interpretation Criteria in Measuring Driven Precast Concrete Pile Uplift Capacity

This paper presents a comprehensive analysis of load test interpretation criteria to determine their suitability to driven precast concrete (PC) pile uplift capacity.  A database was developed containing static pile load tests and utilized for the evaluation. The piles were round and square cross-sections under drained and undrained loading. To explore and compare their behavior, the stored data were categorized into four groups.  In general, the trends of every criterion for the four groups were notably the same. In both drained and undrained loading, slightly larger interpreted capacities were demonstrated by square piles than by round piles. Moreover, round piles demonstrated more ductile load-displacement response than square piles especially in undrained loading. Statistical analyses presented that smaller values of displacements exhibited higher coefficient of variation. The drained and undrained tests were compared and results showed less variability in drained than undrained loading and capacity ratios (Qx/QCHIN) in drained loading were slightly higher than in undrained loading. The interrelationship and applicability of these criteria as well as the design recommendations in terms of normalized capacity and displacement were given based on the analyses

Uncertainty analysis for drilled shaft axial behavior using CYCU/DrilledShaft/143

Drilled shaft axial capacities and their uncertainties were evaluated in this paper. A large load test database of drilled shafts labeled as CYCU/DrilledShaft/143 was compiled for this evaluation. All load tests were performed in the field under drained and undrained soil conditions. The database was made available at ISSMGE TC304 database sharing platform 304 dB. Drained and undrained analyses were conducted separately. These load test data were first analyzed using representative interpretation criteria to determine their “capacities”. The results of each of the interpretation criteria were next normalized by a standard interpretation criterion and a predicted capacity to establish the relationships between these various interpretation criteria and to characterize model factors, respectively. The analyses of 143 drilled shafts indicated that L1 and DeBeer interpreted loads can be recommended for the serviceability limit state design. The criteria van der Veen, 4%B, Terzaghi and Peck, slope–tangent, L2, and Fuller and Hoy yielded values that are at the transition region of the load–displacement curve, in which the “ultimate” capacity can be reasonably estimated. The Chin method is not conservative, because it produced a value larger than all of the above interpreted “ultimate” capacities with displacements exceeding 60 mm on the average and beyond the range of the measured load–displacement curve. The scatter in the load–displacement curves is studied by applying different normalization schemes and fitting the normalized curves to a hyperbolic model. The hyperbolic model (curve fitting) parameters are generally negatively correlated. Statistics of these hyperbolic model parameters are shown to be comparable to values reported in previous studies. This hyperbolic model is widely used for reliability-based design at the serviceability limit state. Hence, the statistics of the hyperbolic model parameters presented in this study are useful

Effects of induction chemotherapy on nutrition status in locally advanced nasopharyngeal carcinoma: a multicentre prospective study

Abstract Background Induction chemotherapy (IC) and concurrent chemoradiotherapy (CCRT) is the standard of care for locoregionally advanced nasopharyngeal carcinoma (LA‐NPC). This intensive treatment regimen increases acute toxicities, which could negatively impact patients' nutritional status. We conducted this prospective, multicentre trial to investigate the effects of IC and CCRT on nutritional status in LA‐NPC patients, so as to provide evidence for further study of nutritional intervention, which was registered in ClinicalTrials.gov (NCT02575547). Methods Patients with biopsy‐proven NPC and planned for IC + CCRT were recruited. IC entailed two cycles of 3‐weekly docetaxel 75 mg/m2 and cisplatin 75 mg/m2; CCRT entailed two to three cycles of 3‐weekly cisplatin 100 mg/m2 depending on the duration of radiotherapy. Nutritional status and quality of life (QoL) were assessed pre‐IC, post‐cycles one and two of IC, W4 and W7 of CCRT. Primary endpoint was the cumulative proportion of ≥ 5.0% weight loss (WL5.0) by the end of treatment (W7‐CCRT). Secondary endpoints included body mass index, NRS2002 and PG‐SGA scores, QoL, hypoalbuminaemia, treatment compliance, acute and late toxicities and survivals. The associations between primary and secondary endpoints were also evaluated. Results One hundred and seventy‐one patients were enrolled. Median follow‐up was 67.4 (IQR: 64.1–71.2) months. 97.7% (167/171) patients completed two cycles of IC, and 87.7% (150/171) completed at least two cycles of concurrent chemotherapy; all, except one patient (0.6%), completed IMRT. WL was minimal during IC (median of 0.0%), but increased sharply at W4‐CCRT (median of 4.0% [IQR: 0.0–7.0%]) and peaked at W7‐CCRT (median of 8.5% [IQR: 4.1–11.7%]). 71.9% (123/171) of patients recorded a WL5.0 by W7‐CCRT, which was associated with a higher malnutrition risk (NRS2002 ≥ 3 points: 87.7% [WL ≥ 5.0%] vs 58.7% [WL < 5.0%], P < 0.001) and requirement of nutritional intervention (PG‐SGA ≥ 9 points: 82.0% [WL ≥ 5.0%] vs 66.7% [WL < 5.0%], P = 0.038). The median %WL at W7‐CCRT was higher in patients who suffered from ≥ G2 mucositis (9.0% vs 6.6%, P = 0.025) and xerostomia (9.1% vs 6.3%, P = 0.003). Besides, patients with cumulative WL5.0 also reported a higher detriment on QoL at W7‐CCRT compared with patients without, with a difference of −8.3 points (95% CI [−15.1, −1.4], P = 0.019). Conclusions We observed a high prevalence of WL among LA‐NPC patients who were treated with IC + CCRT, which peaked during CCRT, and had a detriment on patients' QoL. Our data support the need to monitor patient's nutritional status during the later phase of treatment with IC + CCRT and inform on nutritional intervention strategies