Applied Mechanics and Materials Vols. 438-439

Abstract: Mechanical property of the segment joint for fabricated shield tunnel lining is the key factor for segment lining design and research. Based on the test prototype of shield tunnel segment lining with about 6m diameter, the test scheme of prestressed segment joint has been studied. On account for the influencing factors of prestressing force, prestressed reinforcement shape, joint shape and bending moment, the test structure and test conditions were designed. And the test content and methods were brought out, the test procedure and notes were discussed.

Abstract: Taking working well of tunnel crossing river for example, aimed at construction problem, the software of PLAXIS3D is used to simulate excavation, strut dismantling and water injecting. Several kinds of soil-reinforcing forms are also simulated to analyses the relation between soil-reinforcing form and retaining wall deformation.

Abstract: With characteristics of the long span and soft rock tunnel, this paper analyzes the main factors affecting tunnel stable on the basis of the way of tunnel excavation method. The large finite element program is used in research of a tunnel, with a numerical simulation of two different way, top heading and bench method and double side drift method. From the result of stress field and displacement field of the tunnel , some useful conclusion are obtained, that double side drift method is appropriate for this kind of soft rock tunnel.

Abstract: In order to solve the influence of fire and smoke on personnel in highway tunnel for subtended traffic, analysis of measures against the fire in tunnel from structure was conducted. When the tunnel is on fire, smoke hazards lie in high temperature gas and smoke will choke people to cause deaths, fire hazards mainly lie in high temperature which will burn people to cause deaths. The separation pattern of people and smoke, and the separation pattern of people and fire are put forward. Analysis results show that unilateral closed repair road widened to 100cm is a new and feasible solution. Applying the means of setting up symmetrical emergency parking strips in the single tunnel for subtended traffic can help vehicle escape in the tunnel on fire. Setting rail car on the unilateral repair road in the single tunnel for subtended traffic can realize the separation model of people and fire. The results are significant for safety measures against fire in tunnels, and can provide reference for the subtended traffic design.

Abstract: The theoretical solution to the distribution of axial force in Mindlin displacement problem and the plastic radius of surrounding rock in the condition of elastoplastic homogeneous soil are deduced. Based on the results of field test, the problem of length optimization of systematic bolt in loess tunnel was discussed from the two perspectives of mechanical characteristic under the drawing force and the axial force at the location of neural point. The obtained results will offer the technical support for the length optimization of systematic bolt in loess tunnel, which has the guiding significance in the design and construction.

Abstract: This paper analyzes various factors about the surrounding rock stability in tunnel, on this basis, proposes control methods and ideas about the surrounding rock stability in tunnel, and discusses in detail the relationship of bolt working load and the surrounding rock stability. Using the approach of non-destructive monitoring bolts can be well monitor the surrounding rock stability of entire process. The result will provide great reference for research studies on stability of surrounding rock and the engineering construction.

Abstract: Due to the construction technology and concrete structure of tunnel, cavity can be engendered in the composite lining. To evaluate the influence of the cavity on tunnel lining, cavity must be first detected, and safety evaluation of tunnel structure can be taken with the detection results. With the tunnel engineering example, a typical section chosen has been checked, and the safety of cavity was evaluated. It can provide a reference method for the detection and safety evaluation on cavity in tunnel lining.

Abstract: For a comprehensive analysis of the mechanical properties of compound-umbrella arch in the unsymmetrically loaded tunnel entrance, we focus on the force characteristics to optimize the structure of composite umbrella arch, and improve its economic efficiency. The stresses on the bottom of pile, the pile and the steel arch were monitored, and analyzed by the finite element software. The results show that, on the bias terrain, the stress of the pile bottom is nonuniform with uneven settlement. The stress distribution is very complex, where the tensile stress appears on the pile bottom, the compressive stress takes place on the arch foot and the vault, which is not good to the stability of the overall umbrella arch. As both sides of the umbrella arch bear a large different force, the piles on both sides of the umbrella arch subject to large bending moment and axial force, which improve the stability of the tunnel entrance.

Abstract: Under the background of engineering application, a 3-D FE analysis was carried out to evaluate the loading performance of a two-hole pair-arch tunnel under-across the main canal of South-to-North Water Transfer Project. In fact, the tunnel was constructed in integral longitudinally without obeying the design requirement of parting within certain length. The analysis showed that the vertical deformation and tensile stress along the longitudinal axis are obviously affected by the loads from main canal, moreover, the tensile stress exceeds the limit of tensile strength of concrete, which may lead thoroughly cracks on top plate of tunnel. This analysis determined the crack zone which should be dealt with.

Abstract: This article calculates the thermal fields and thermal stress fields of the subway tunnel concrete during construction using finite element software ABAQUS. With the calculating laws of distribution of the two fields mentioned above, this paper provides several suggestions for designing and constructing of subway tunnel.