Applied Mechanics and Materials Vols. 744-746

Abstract: By Inverse analysis through the actual monitoring data and laboratory test, get physical and mechanical parameters of rock and soil mass, use the numerical simulation method to simulate the surface subsidence process of Qingdao city tunnel ZK1 + 810 ~ ZK2 + 810 interval caused by two tunnel excavation methods (the actual use of up and down the steps method and the planned use of the advancing drift whole section method) and comparatively analysis surface subsidence caused by the two methods of construction. The research results show that the surface subsidence causes by the two kinds of construction technology are experienced four stages, namely the impact in advance stage of rapid growth stage, slow growth stage, subsidence and subsidence stabilization stage; The maximum value of surface subsidence caused by up and down the steps method of excavation is greater than that of the advancing drift whole section method; transverse range of ground surface settlement induced by step excavation is about 2D from both sides of the center line of the tunnel, the horizontal range of surface subsidence in advancing drift under construction is generally about 1.5 D ~ 2 D; longitudinal range of the surface subsidence caused by advancing drift under the construction is smaller than method of up and down the steps. The conclusion provides the technical support for the tunnel design and construction.

Abstract: Water curtain efficiency test is the key method to evaluate the tightness and reliability of water curtain system. This thesis taking the cavern in Yantai as an example, based on the data of three different hydrodynamic condition stages during efficiency test, in combination with the important judgment parameter of water curtain efficiency-critical pressure value, the low efficiency of rock area was revealed by analyzing and evaluating the conduction effect of fissure water pressure. In order to improve the efficiency, drilled additional boreholes in low efficiency area. At last, through the test to evaluate efficiency improvement of new drilled boreholes. The test result shows that: the water curtain efficiency test can able to accurately determine the low efficiency area in rock mass, additional boreholes can significantly improve the pressure of low efficiency boreholes and can achieve the tightness requirements of cavern.

Abstract: The special geological conditions of talus are often encountered in southwest China, it brings a lot of difficulties to tunnel construction. The formation mechanism and developmental properties of talus are analyzed in this paper. Based on field investigation on talus diseases, the hazard to tunnel engineering induced by talus and its corresponding measures are also analyzed. The results can be used for the safe and fast construction of tunnels which go through talus deposit.

Abstract: With the development of in the western area, transportation infrastructure meets more and more tunnels covered by loess soil. During the excavation of these tunnels, special geological problems are inevitably encountered when through the loess-rock interface. With regard to these problems, the present paper establishes a three-dimensional numerical model by finite different software Flac 3D. Based on this model, the up-down excavation processes of the tunnel through loess-rock interface are simulated.

Abstract: In this paper, a comprehensive method combined spot-survey and numerical simulation tests has been used to make an approach to systematically study of the technology of level artificial ground freezing in tunnel connecting passage construction. By simulating the freezing process of artificially frozen soils of Dalian Road tunnel connecting passage with finite element analysis method, the varying laws of temperature fields, displacement fields and stress fields had been worked out. According to the results of actual field survey, the changing laws of frost heave pressure and tunnel deformation with freezing temperature, elapsed freezing time during the artificial ground freezing period are obtained. The laws from finite element analysis are consistent with that from field survey, which has proved that finite element analysis is correct. The conclusions of the research prove the advantages of horizontal artificial ground freezing in such similar construction and set up a successful model for related freezing projects in the future, which, will guide the coming practice and safeguard the success.

Abstract: Based on the background of Dalian subway running through bridge pile foundation, a 3d numerical model is built by the finite element software MIDAS/GTS in order to research the laws of the internal force and the displacement of the pile and soil during the Construction process. The outcome reflects that the sedimentation value of the top of the pile is bigger than others. Because the bigger thrust about the shield machine, the horizontal displacement of the pile is increasing at first and decreasing at last from a positive into a negative. Because of the loss of the soil, the soil beside the pile collapses and causes strong friction force. The surface sedimentation value which is near the central line of the tunnel is bigger than other place. This paper is of good reference roles in the similar underground engineering in Dalian.

Abstract: Put the first Phase Project of Qingdao Metro (line 3) civil 03 bid section TAI-YAN interval of blasting construction as the background In this paper,select the test section to blasting test,in groundposition on the ais of the tunnel workface arrange the measuring points and location of measuring points remain the same.Based on the measured data, studied on the law of blasting vibration of cutting parts of each of the driving cycle.The research result show that the cutting part of vibration velocity peak appeared in behind the tunnel woekface 1~3m;Rear vibration composite speed of the tunnel workface is speed of the tunnel workface is 1.0~1.4 times in front of the particle vibration composite speed;The main vibration frequency in front of tunnel workface and rear particles are above 15HZ.

Abstract: As a new method, the three-bench seven-step-excavation method is more and more adopted by the construction of large span tunnel in weak rock mass. At the portal of Yunyangshan tunnel, there is a long section of the mild clay stratum. Considered that the whole excavated cross section area is very large, the three-bench seven-step-excavation method was adopted. In order to investigate the surface settlements caused by the construction of twin tunnels, three typical cross-section were selected. At each section, the ground surface settlements were monitored. It is shown that the depth of tunnel and the construction time of twin tunnels have influence on the surface settlement curves, and the three-bench seven-step-excavation is effective in the mild clay stratum.

Abstract: This paper analyzes the measured data on Yushiling dam blast vibration which affected by blasting Yushiling Tunnel Construction,the results show that the monitoring of the dam each measuring point are below the maximum blasting vibration safety control standards, measured master oscillator frequencies greater than 20Hz, does not cause the dam resonance, vibration and shock wave generated by a small deformation of the dam, the dam did not cause abnormal deformation, the result of dam safety assessment to provide a scientific basis, and provide reference for similar projects.

Abstract: This paper proposes safety management evaluation system of metro station project based on factors which the construction techniques and process of drilling-blasting metro station involved.Then the paper uses the OWA operator to determine the weights of the index and adopts gray theory to evaluate safety of drilling-blasting metro station construction based on measure of metro station project safety management.Finally,the paper puts forward recommendations of safety management according to the evaluation results.