Current Issue : April - June Volume : 2018 Issue Number : 2 Articles : 5 Articles
Water inrush from the excavation face often occurs in the current shield construction of metro tunnels. In this study, the\ndiscontinuity of shield tunnel lining and the interaction between the tunnel segments, the grouting layer, and the surrounding\nrock are considered. Based on the 3D nonlinear contact theory, a hybrid model of the shield tunnel is constructed. Considering\nthe fluid-solid coupling effect of water and soil, the influences of different water head differences on the mechanical\nperformance and deformation of segments and joints in the shield tunnel are studied. The water gushing from the excavation\nface leads to vertical convergence of the cross-sectional area of the shield tunnel, and joint opening and dislocation result in\nsharp decrease of the waterproof capacity of joints. Meanwhile, the stress in the vicinity of segment joints increases sharply,\nand local cracks occur in the segment lining. The axial force, shear force, and bending moment in the joint bolt are also\nsignificantly increased. Based on the currentmetro standard and the computational results in this study, an emergency control\ncriterion is put forward by means of controlling the discharge of water: the water head difference over the excavation face is\nrequired less than 4.6 M....
This study focuses on identifying and evaluating critical parameters of various drainage configurations, arrangement, and filter which\naffect the efficiency of water draining system in slopes. There are a total of seven experiments with different types of homogeneous soil,\ndrainage envelope, filter material, and quantity of pipes performed utilizing a model box with a dimension of 0.8mÃ?â?? 0.8mÃ?â?? 0.6 m.The\npipes were orientated at 5 degrees from the horizontal. Rainfall event was introduced via a rainfall simulator with rainfall intensity of\n434.1 mm/h. From the experiments performed, the expected outcomes when utilizing double pipes and geotextile as envelope filter\nwere verified in this study. The results obtained from these experiments were reviewed and compared with Chapter 14 ââ?¬Å?Subsurface\nDrainage Systemsââ?¬Â of DIDââ?¬â?¢s Irrigation and Agricultural Drainage Manual of Malaysia and the European standard. It is recommended\nthat the pipe installed in the slope could be wrapped with geotextile and in tandem with application of granular filter to minimize\nclogging without affecting the water discharge rate. Terzaghiââ?¬â?¢s filter criteria could be followed closely when deciding on new\nmaterials to act as aggregate filter. A caging system could be introduced as it could maintain the integrity of the drainage system and\ncould ease installation...
Rainfall is inevitably one of the main factors that trigger landslides. However, not much study has been conducted on the impact of\ngroundwater rise on slope stability. Thus, this study is intended to focus on the rise of the groundwater level from the bottom of the\nslope which would lead to landslides due to pore pressure development by eliminating other landslide-triggering factors\n(i.e., infiltration and surface runoff). Saturated sand was used for slope modeling, and sand densities of 1523 kg/m3, 1562 kg/m3,\nand 1592 kg/m3 were tested with a constant slope angle of 45�°. Another set of experiments was also performed on slopes having\nangles of 25�°, 45�°, and 60�° and with a maintained density of sand at 1562 kg/m3. Through observation, failure was initiated first at\nthe toe of the slope before minor and major slips or total collapse occurs. Dimensions of slip surfaces were measured and included\nin SLOPE/W for the computation of the safety factor. In conclusion, safety factors are found to be higher in denser soil and in the\nlowest slope angle. However, faster occurrence of collapse in denser soil was identified and could be contributed by the faster pore\nwater pressure development...
This paper examines shaft and base grouted concrete piles by conducting vertical static load tests (SLTs) and dynamic load tests. Three\nconcrete piles with shaft and base grouting, with base grouting only, and without grouting techniques were selected, and compressive\nSLTs were conducted. Two piles with grouting were also assessed with dynamic load tests. Another two uplift SLTs were conducted to\none shaft and base grouted pile and one pile without grouting. Traditional presentations were provided to check whether the bored\npiles reached the design requirement. Interpretations of test results were also provided to determine the ultimate pile capacity. Results\nfrom these 5 SLT programs indicated that double-tangent and DeBeer�s methods are close to each other, and Chin�s method\noverestimates the pile capacity. Comparison of the results from the SLTs and dynamic load tests shows that the results from Chin�s\nmethod are close to dynamic results, and Mazurkiewicz�s method overestimates for friction resistance. The results also demonstrate\nthat base and shaft grouted pile and base grouted pile increase by 9.82% and 2.89% in compressive capacity, respectively, and\ncompared to the uplift SLTs; there is a 15.7% increment in pile capacity after using base and shaft grouting technology....
In order to properly design strengthening intervention of existing buildings, careful assessment of the structural behavior is\ncertainly required. This is particularly important when dealing with historical constructions made of heterogeneous materials like\nmasonry or stonework. In this context, this paper presents the results of knowledge process on a large monumental nineteenth\ncentury building located in Trieste. The traditional investigation approach considering a wide number of destructive tests for\ncharacterization of materials and evaluation of the structural details were not admissible due to the valuable cultural and historical\nimportance of the building. Therefore, an alternative and not conventional investigation approach has been considered. After\na wide historical research and a detailed structural survey, it has been possible to identify the main structural systems of the\nbuilding. Then, to characterize the structural response, a limited number of nondestructive tests but on full-scale typological\nsystems have been preferred to a larger number of destructive tests on specimens of the different materials. The selected experimental\nload tests have been conducted in order to assess the actual structural response of the main systems that constitute the\nbuilding, thus allowing for a fine tuning of both the rehabilitation interventions and the numerical finite element models....
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