PERBANDINGAN DEFORMASI DINDING PADA BASEMENT METODE TOP-DOWN DENGAN ANALISIS CONSTRUCTION STAGE DAN ANALISIS KONVENSIONAL

ABSTRACT In basement construction with the top-down approach, excavation and slab installation work are carried out in stages. However, not all geotechnical applications can simulate construction stages, hence this effect has been ignored by many engineers in practice. Therefore, in this study, the effect of basement construction stages is analyzed using MIDAS GTS NX. In the program, two different analyses are performed. The first analysis is the construction stage analysis that simulates construction stages. As a comparison, a conventional analysis is performed which doesn't simulate construction stages. The two analysis results are compared. This analysis focuses mainly on the wall deformation. The modeling consists of 5 excavation stages (17 meters deep) and a diaphragm wall (36 meters deep). The walls are given 5 layers of slab reinforcements. In the first excavation stage, the maximum wall deformation results in both analyses show slightly different results (the construction stage analysis result is 8% greater than that of conventional analysis). However, in the final excavation stage, a significant difference is shown (the construction stage analysis result is 37% greater than that of conventional analysis). These results indicate that the effect of construction stages should not be neglected, especially in multi-story basements with top-down construction.ABSTRAK Pada konstruksi basement dengan metode top-down, pekerjaan penggalian dan pemasangan pelat dilakukan secara bertahap. Namun, tidak semua aplikasi geoteknik dapat mensimulasikan tahapan konstruksi sehingga pengaruhnya sering diabaikan oleh banyak insinyur dalam praktiknya. Maka, pada penelitian ini dilakukan analisis pengaruh tahapan konstruksi basement menggunakan aplikasi MIDAS GTS NX. Pada program, akan dilakukan dua analisis yang berbeda. Pertama, dilakukan analisis construction stage yang mensimulasikan tahapan konstruksi. Sebagai perbandingan, dilakukan analisis konvensional yang tidak mensimulasikan tahapan konstruksi. Kedua hasil analisis dibandingkan. Analisis ini lebih berfokus pada deformasi yang terjadi pada dinding diafragma. Pemodelan terdiri dari 5 tahap galian dengan kedalaman 17 meter dan dinding diafragma dengan kedalaman 36 meter. Dinding diberi perkuatan pelat sebanyak 5 lapis. Pada galian tahap pertama, hasil deformasi maksimum dinding pada kedua analisis menunjukkan hasil yang tidak jauh berbeda (hasil analisis construction stage lebih besar 8% dibandingkan hasil analisis konvensional). Tetapi pada galian tahap akhir, hasil deformasi maksimum dinding pada kedua analisis menunjukkan perbedaan signifikan (hasil analisis construction stage lebih besar 37% dibandingkan hasil analisis konvensional). Hasil ini menunjukkan bahwa pengaruh tahapan konstruksi sebaiknya tidak diabaikan khususnya pada basement bertingkat banyak dengan metode top-down.

Localized Pulmonary Vein Scar Promotes Atrial Fibrillation in High Left Atrial Pressure

BackgroundPulmonary vein (PV) ablation is unsuccessful in atrial fibrillation (AF) patients with high left atrial (LA) pressure. Increased atrial stretch by increased pressure is proarrhythmic for AF, and myocardial scar alters wall deformation. We hypothesized that localized PV scar is proarrhythmic for AF in high LA pressure.MethodsRadiofrequency energy was delivered locally in the right PV of healthy sheep. The sheep recovered for 4 months. Explanted hearts (n = 9 PV scar, n = 9 controls) were perfused with 1:4 blood:Tyrode’s solution in a four-chamber working heart setup. Programmed PV stimulation was performed during low (∼12 mmHg) and high (∼25 mmHg) LA pressure. An AF inducibility index was calculated based on the number of induction attempts and the number of attempts causing AF (run of ≥ 20 premature atrial complexes).ResultsIn high LA pressure, the presence of PV scar increased the AF inducibility index compared with control hearts (0.83 ± 0.20 vs. 0.38 ± 0.40 arb. unit, respectively, p = 0.014). The diastolic stimulation threshold in high LA pressure was higher (108 ± 23 vs. 77 ± 16 mA, respectively, p = 0.006), and its heterogeneity was increased in hearts with PV scar compared with controls. In high LA pressure, the refractory period was shorter in PV scar than in control hearts (178 ± 39 vs. 235 ± 48 ms, p = 0.011).ConclusionLocalized PV scar only in combination with increased LA pressure facilitated the inducibility of AF. This was associated with changes in tissue excitability remote from the PV scar. Localized PV ablation is potentially proarrhythmic in patients with increased LA pressure.

ON THE DIFFERENT VELOCITIES OF INLET BOUNDARY CONDITIONS FOR HUMAN ARM ANALYSIS OF ARTERIAL FLOW USING ONE-WAY FLUID–SOLID COUPLING

Simulations for blood hydrodynamic problems have been still largely incomplete despite years of research, especially for the inlet of boundary conditions that served as an essential part in computational fluid dynamics simulations of blood flow in human arteries. In this paper, the four different velocities of inlet boundary conditions were tested and compared in the human arm arterial model developed by us previously. Based on the selected points of nine key areas in the blood model,[Formula: see text] we analyzed the calculation results of pressure and shear stress distributions in detail. Our results show that they are changeable in different [Formula: see text] (different peak velocities of inlet boundary). The results further show that the static pressure of the aortic tree is higher than the static pressure of the branch, while the shear stress of the aortic tree is lower than the shear stress of the branch. On the other hand, the velocities changed in different [Formula: see text], the vessel walls of max total deformation appear in the middle radial obviously, compared with the equivalent and shear stress show at the entrance and bifurcations. In all, the simulation results of the brachial arteries provide the wall deformation, pressure and shear stress characteristics in different [Formula: see text], and offer a new strategy to study the two-way coupling of hemodynamics in the arm arterial model.

Computed Tomography Images under Optimized Iterative Reconstruction Algorithm for Blood Flow Field Characteristics in Cerebral Aneurysm before and after Stent Implantation

In order to study the analysis of blood flow field characteristics of cerebral aneurysm patients before and after stent implantation based on CT images of ART-TV-PI, this paper firstly improved the ART-TV algorithm of algebraic reconstruction technology and obtained the ART-TV-PI algorithm, which was compared with the ART algorithm and ART-TV algorithm. Afterwards, the CT images based on the above three algorithms were used to analyze the changes of average blood flow velocity, average wall pressure, average wall deformation, and average shear force of 48 cases of cerebral aneurysm patients before and after stent implantation. The results showed that the mean square error and radiation dose of the ART-TV-PI algorithm (0.00012 and 1.65 mSv) were significantly lower than those of the ART algorithm (0.0031 and 3.09 mSv) and ART-TV algorithm (0.00082 and 2.52 mSv), and the signal-to-noise ratio (23.94) was significantly higher than those of the ART algorithm (11.32) and ART-TV algorithm (16.89), with statistically significant differences ( P < 0.05 ). The differences of mean blood flow velocity, mean wall pressure, mean wall deformation, and mean shear force before and after stent implantation among the three algorithms were not statistically significant ( P > 0.05 ), and the average index of the ART-TV-PI algorithm was the highest. Under the ART-TV-PI algorithm, the mean blood flow velocity (0.044 m/s), the mean wall pressure (71.7 Pa), the mean wall deformation (0.057 mm), and the mean shear force (889 Pa) after stent implantation were significantly lower than those before stent implantation (0.165 m/s, 160.8 Pa, 0.721 mm, and 2690 Pa), with average decreases of 73.3%, 55.4%, 92.1%, and 64.3%, respectively, and the differences were statistically significant ( P < 0.05 ). In conclusion, the images reconstructed by the ART-TV-PI algorithm have good image quality, which provides great convenience for surgical examination of cerebral aneurysm stent implantation and is worthy of clinical application.

A Modified Elastic Foundation Beam Method for Analyzing Lateral Wall Deformation in Excavations with Cross Wall

Cross walls have been used as alternative auxiliary measures to protect buildings in some areas of Asia. Realizing the inadequacy of the classical Winkler foundation to predict the deflection of the diaphragm wall with cross wall, a modified Winkler foundation of the finite element method (MEFB) was formulated in this paper. Then, the MEFB method was verified through two excavation cases and applied in a new well-documented excavation history. Results showed that the wall deflection by the proposed method was line with the 3D numerical analysis and field observations but smaller than that of classical Winkler’s elastic foundation (EFB) method. The maximum deformation calculated by the MEFB method was predicted to have a reduction of 40∼60% compared to those of the EFB method. Meanwhile, the wall deformation was minimum at the location of cross walls and reaches the maximum value at the midline between two cross walls. Besides, the plane strain ratio PSR d based on the MEFB method was defined to study the interval L , the embedded depth, and arrangement of cross walls. The results indicated the MEFB method was used successfully as a more accurate method than Winkler foundation and is simpler than 3D numerical analysis method for the engineering design of the diaphragm-cross wall system during excavation.

Predictive assessment of the stability of quarry sides

The composition of the rocks composing the quarry sides and the approximate slope angles in accordance with the mining and geological conditions are described. The issues of creating observation stations are considered taking into account seasonal temperature fluctuations of the benchmarks. Observation materials are generalized, the degree of danger of deformations is established on the basis of observations of deformation speed. The mining safety control methods are described. The disadvantages of the approach to data processing and analysis are identified. A criterion for mine surveying prediction of the pit wall stability based on the comparison of critical and actual relative deformations is proposed. The purpose of the local forecast of wall deformation is to control the stability of non-working and working slopes of the sides, and to confirm the efficiency of the method used. The predictive assessment was carried out on the shift of working benchmarks on one of the open pits of Transbaikalia. It is suggested monitoring the stability of rocks using oscillograms obtained by seismic equipment.

Symptomatic arterial hypertension in extrasystolic arrythmia

Funding Acknowledgements Type of funding sources: None. Within the main causes of the secondary arterial hypertensions the main roles play renal, endocrine and hemodynamic. In the list of reasons of the secondary hemodynamic arterial hypertension there’re no extrasystoles. Purpose. To determine the relationship between different types of extrasystoles and the the secondary hemodynamic arterial hypertension. Materials and methods. We observed 132 patients with supraventricular and ventricular extrasystoles. Extrasystoles were divided into groups due to the moment of their appearance in cardiocycle: 1. Extrasystoles before the mitral valve opening. 2,3. Exstrasystoles in phase of fast ventricules filling before and after the peak of transmitral blood flow. 4. Extrasystoles in slow ventricules filling phase. 5. Other extrasystoles (allorrhythmias and group extrasystoles). The reason for that dividing was the different contribution of each type into the hemodynamics and heart output. We analyzed the regular, extraordinary and first post-extrasystolic contractions. Intra-arterial blood flow was estimated by ultrasound-doppler. The moment of extrasystoles appearance was determined by echocardiography, electrocardiography and 24-hours ECG monitoring. The kinetics of vessel wall was calculated by sphygmograms and included speed, acceleration, power and work parameters. The BP measuring was made by Korotkov method that the moment of measuring was in the first post-extrasystolic wave on sphygmogram. We duplicated it after the normalization and calibration of carotid arteries sphygmograms. Results. The main importance to the hemodynamic changes has the moment of extrasystole appearance in cardio cycle and the ability of the first post-extrasystolic contraction to reestablish an adequate resulting blood flow. It is characterized by: stroke volume rising from 5 to 40%; systolic BP increase up to 30% (with formation of the secondary hemodynamic AH) compared with the systolic BP with normal heart rate; rising of arterial walls kinetic parameters (speed, acceleration, power, work); blood flow velocity rising; grown arterial wall deformation. The maximum of these parameters was in first post-extrasystolic contraction with extrasystoles before the mitral valve opening and extrasystoles before the transmitral peak blood outflow. The special hemodynamic situation appears when there’re allorrhythmias when, for example, in case of constant bigeminia, BP is increased in 50% of time, and in case of trigimenia – in 1/3 of time. Conclusion. We believe it’s necessary to include extrasystoles into the list of the reasons of the secondary hemodynamic arterial hypertension. The main features of this type of AH are: unstable BP rising, prevalence growth of systolic BP, direct relationship with extrasystoles’ appearance moment. The risen blood flow of first post-extrasystolic contraction can be the reason of additional arterial walls deformation and complications that may cause the any AH.