Advanced Materials Research Vols. 261-263

Abstract: The construction of slope or underground engineering often encounters soft rocks, which control the stability of rock engineering, with obvious characteristics of rheology. Under step load conditon, the shear creep test of argillaceous siltstone is performed by using the RMT150c rock and soil mechanics testing machine. Testing results show that the amount of creep deformation for argillaceous siltstone is big enough, which should be taken into consideration for analysis of stability or design of slope or underground engineering. Based on testing results, the long-term shear strength parameters are determined to provide theory basis for engineering survey and design.

Abstract: The effect of seepage force on tunnel face stability with pipe roof reinforcement was studied based on the kinematic method of limit analysis. This method can be employed to define the safety factor and its corresponding critical failure mechanism for a given tunnel. The studies revealed that the existence of groundwater may seriously affect the face stability. Under the steady-state groundwater flow condition, most part of the total support pressure is owing to the seepage pressure acting on the tunnel face. There was a relatively large reduction in the seepage pressure by adopting the pipe roof reinforcement technique.

Abstract: The method to calculate rock pressure for shallow asymmetric tunnel is analyzed by means of taking a mountainous tunnel with semicircular crown and straight sidewall as the object in this paper. The calculation method of tunnel rock pressure has been presented with consideration of both tunnel structure size and its overburden depth. Finally the way to determine the shallow or profound depth of asymmetric tunnel is also obtained.

Abstract: A soil water characteristic curve (SWCC) can describe the relationship between unsaturated soil matric suction and water content. By analyzing and researching the test data of the soil water characteristic curve researchers can initially establish the SWCC equation and apply this equation to the actual engineering analysis. In another words, this article is based on the fluid-solid coupling theory of unsaturated soil used to analyze and study the problem of land subsidence caused by tunnel construction. Numerical calculations show that the coupling results agree well with the measured curve works.

Abstract: The ground-liner interaction research has important engineering value for the underground engineering design optimization and evaluation of construction safety. The interface between ground and liner is considered. In this paper, the effect of different ground-liner stiffness ratio, lateral pressure coefficient, thickness and different interface stiffness ratio and other factors on the support structure for internal forces and interface stress is analyzed. The analysis results show that liner internal force and interface stress increase with the increase of stiffness ratio between liner and ground, and the impact is very significant. Effect of lateral pressure coefficient on liner internal force and interface stress mainly reflects on laws around the cavern, where 1 is the limitation of lateral pressure coefficient. It presents symmetrical distribution. With the increase of liner thickness, the liner internal force and interface normal stress increase, but it make no difference to the contact interface tangential stress.

Abstract: Considering different types of building structure and foundation, the system refers to acceptable ground settlement and acceptable soil loss ratio was established by establishing the control of building’s bending and deformation. The system which adopted Delphi dynamic data binding technology and used Access as database was developed by Delphi7.0 visual tools. The system which named "Analysis system about shield tunnel construction to adjacent buildings" is developed to judge the extent of damage of buildings influenced by adjacent shield tunnel construction.

Abstract: Shed-tunnel is one of common prevention measures along the highway. First, denoised the rockfall impact signal when the rock impact the ordinary shed-tunnel and the energy dissipation shed-tunnel by the wavelet theory. The calculation result indicated that the wavelet theory’s denoise effect is very good. Then, pick-up each frequency band’s the rockfall impact signal, and analysed the energy for each frequency band’s impact signal. The result indicated that the energy dissipation shed-tunnel’s impact energy concentrate in the low frequency part. There are only 0.4% impact energy in the high frequency part. Besides, the energy dissipation shed-tunnel’s impact energy in the low frequency part is higher than the the ordinary shed-tunnel, and the energy dissipation shed-tunnel’s impact energy depressed velocity when the impact frequency increase is fast than the ordinary shed-tunnel. So the energy dissipation shed-tunnel’s design must consider the low frequency impact,and could ignore the high frequency impact.

Abstract: The analyses on the statistical probability of the response spectra have an important role in determining the earthquake demand. Elastic and inelastic spectra on acceleration of the 369 records with a long characteristic period for SDOF systems were presented in statistical analyses. The empirical probability distributions of the spectral values were derived according to the Kolmogorov-Smirnov (KS) goodness-of-fit test. And the spectra considering the probability guaranty were developed to investigate the characteristic of the response spectra. The formula for statistical average spectra of the ground motion ensemble were recommended, which were valuable for current research and code revisal. The results show:(1)the inelastic responses decrease with the increase of ductility demand μ when μ<4, and they decrease unclearly when μ≥4;(2) the inelastic spectra has a large value of Cov (coefficient of variance),the Cov range from 0.2 to 0.3 when T<1s,and it increases linearly when T≥1s;(3)the probabilistic distribution of the spectra value on acceleration is validated as the lognormal or the Gumbel type I distributions;(4) the probabilistic spectra may be a feasible way to determine earthquake load in the future.

Abstract: Latent crack has no obvious effect on fracture process in the shallow rock engineering. As the project entered into deep part, there appeared many phenomenon which is different from that in the shallow rock engineering, and latent crack plays a more and more important role. By analysis of micro defects of rock and numerical method, potential paths of crack propagation are prefabricated, and adjust the quantity and spreading direction of latent cracks, then by using the numerical test result and mathematical statistics, the paper analyzes the function of latent crack of different level in the process of fracture. The results show that fracture strength and latent crack of rock have close relationship with each other, and rock fracture strength is related to the spreading direction of latent crack, and the smaller the angle between latent crack and major fracture crack is, the greater effect it is on rock fracture strength. As the number of latent crack increase, the effect of the spreading direction of latent crack on rock fracture strength decreases, and the influence degree is depends on their connectivity degree among latent cracks.

Abstract: The soft soil is covered widely in China. Soft soil has obvious rheological character, it will induce landslide etc serious geologic disasters, and make severe threaten to stability and security of projects. The dynamic loading such as earthquake, raging billow, vibration are the important factors and mainly power of inducing landslide geological disaster. The rheological parameters of soft soil are tested and analyzed under dynamic loading, and the rheological model of soft soil is established. All these have important theory and actual signification for us to reveal rheological dynamic mechanism of landslide geological disaster under dynamic loading.