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Anchored bolts are well known as an effective measure to support the rock masses, after all with stiff steel bolts being inserted into them. Although numerous researches have been carried out on anchored joints, the effects of anchored bolts on rock mass containing nonpersistent joints were rarely investigated. In the present study, in order to make up for the deficiency of research, we carried out experimental study on the effect of anchored bolts on failure and strength behavior of nonpersistent jointed rock model. Specifically, the unbolted and bolted rocklike samples with one set of nonpersistent joints were carefully prepared and subjected to the uniaxial compression tests. The strength and failure behavior of jointed rock mass with/without bolts were systematically compared and analyzed. The results demonstrated the effect of joint dip angle and joint spacing on the failure behavior of jointed rock model. The anchored bolts mainly increased the strength of jointed samples having joints of intermediate dip angles such as α = 30°, 45°, and 60°, which fail in a mechanism of Shear Failure along the Joint Plane. The anchored bolts support the jointed rock models through providing lateral constraints and “pin” effect. Even though the anchored bolts work better for the intermediate dip angle situations to increase the bearing capability than for low dip angle (e.g., α = 0° and 15°) and high dip angle (e.g., α = 75° and 90°), they provide limit support strength such that cannot eliminate the influence of nonpersistent joints. [ABSTRACT FROM AUTHOR]

Exploring the flow mechanism of fluid in rock mass is important in solving the water inrush problems during tunnel excavation. However, it is difficult to obtain an undisturbed rock mass from the actual site conditions and study the flow mechanism of fluid through a fracture network composed of multiple single fractures. Therefore, a solution to simulate rock seepage using rock-like samples with single microfracture was presented in this paper. Water flow through microfracture was tested and the deformation of microfracture was recorded by quasi-distributed fiber Bragg grating (FBG) technology. Experimental data showed that Forchheimer's law and Izbash's law could well describe the nonlinear relationship between flow velocity and hydraulic gradient. The coefficient b in Forchheimer's equation decreased with the increase of microfracture aperture. A critical value of E = 0.8 was proposed to classify the nonlinear flow regime: weak turbulence (E < 0.8) and fully developed turbulence (E > 0.8). [ABSTRACT FROM AUTHOR]

There is an increasing trend of tunnel infrastructure construction in cold regions due to the advance of a western development strategy. To reduce the frost damage sustained by a tunnel, it is important to consider the mechanical properties of frost heave in the surrounding rock by analyzing the anisotropic frost heave of a cold-region tunnel. This paper elaborates on the behavior of anisotropic frost heave in the rock surrounding a cold-region tunnel, and the coefficient of displacement relief is adopted to indirectly quantify the influence of the tunnel construction process. The analytical elasto-plastic solutions of the stress and deformation in the surrounding rock are derived with Drucker-Prager criteria (hereinafter referred to as the D-P criteria) by modifying the constitutive equation for the frozen surrounding rock. Finally, an example is given to obtain the influence law of the distribution of stress and deformation in the surrounding rock. The results indicate that the plastic radius and frost force calculated by considering isotropic frost heave are greater than those obtained by considering anisotropic frost heave. The influence of the related parameters also analyzed. Some useful insights are provided for future numerical simulations and the design and construction of cold-region tunnels. [ABSTRACT FROM AUTHOR]

An artificial crust layer formed by in-situ stabilization combined with pre-stressed pipe piles over soft ground has been proposed to reduce foundation settlement in road construction. To analyze the effects of the artificial crust layer, the field measurements from a road project, including the strength of field stabilized soil, settlement and the load distribution between soils and piles were investigated. The results showed that the ratio of 28-day field unconfined compressive strength to laboratory strength ranged from 0.28 to 0.45 at the same stabilized agent. Additionally, the artificial crust layer had a greater compression modulus and strength compared with soft clay, so that the deformation of stabilized soil only accounted for about 5% of the total settlement. The foundation consolidation speed was slower because of the impervious properties of the artificial crust layer. [ABSTRACT FROM AUTHOR]