Advanced Materials Research Vols. 1065-1069

Abstract: The deformation and failure characteristics of rock have a decisive influence on the value of the heritage itself. Therefore, the rock samples were taken from the HeLanKou rock paintings area. The triaxial compression test was completed with the multi-function apparatus RMT-150C. Then the deformation and failure analysis were analyzed. The results show that the porosity and water imbibition are all low. The triaxial compression strength is high. The rock belongs to brittle material. The results can provide data support and reference for HeLanKou rock paintings protection.

Abstract: It is imperative for 3D modeling of mining or underground engineering to precisely and efficiently describe various interfaces, which is also the precondition for 3D visualization of underground engineering. NURBS (Non-Uniform Rational B-Splines) curve and surface technology are introduced in the paper. With help of analyzing 3D geologic structure of Laohutai mining area and comprehensive treatment of surfaces of tunnels and geologic structures. 3D geological surfaces of mining area are built which is the base of building complex 3D geologic modeling.

Abstract: Abstract. The horizontal displacement of soil in slope and the change law of ground surface settlement are dynamically analyzed by building three dimensional-model of foundation pit with the finite element software, ABAQUS, to simulate the construction process of excavation and support, to figure out the influence of micro pile and waterproof curtain on composite soil nailing wall. The study indicates that mechanical model of soil nailing, waterproof curtain, micro pile, pre-stressed anchor interacting with soil can better simulate the construction process of composite soil nailing wall support and have higher calculation accuracy. The calculation can provide a reference for the design and construction of composite soil nailing wall.

Abstract: In-situ bearing plate deformation test, shear test, tri-axial test and pull-out test of anchor were undertaken with the goal of evaluating the bearing capacity, the water permeability and the lateral fraction of the underwater Neocene sandstones. The characteristic of strength is related to structure of rock mass and especially influenced by humidity environment. Before in-situ testing, high pressure pendulum gush waterproof curtain and well-point dewatering were adopted. The samples of mechanical tests were gained from rotary drilling which drill diameter was 1m. The mechanical strength parameters gained form different tests are analyzed. The results indicate that the underwater Neocene sandstone has pore water, and changes into dense sand permeable layer disturbed by excavating. Mechanical strength is related to environmental conditions significantly and reduces with the exposure time increasing. The characteristic value of subsoil bearing capacity of surface disturbance of underwater Neocene sandstone (UNS) can be corrected similar to sand.

Abstract: Based on the results of confined rheological compression test of unsaturated soil samples, some important characteristics and its effective factors have been discussed by using three-dimensional model. At first, the curves of lateral stress relaxation show the process of correspondence with vertical creep. Secondly, it is lateral total stress, and not effective stress, that is relaxed with time because of the volume viscidity of pore water and the shear viscidity of soil skeleton. At last, the limited steady rheological state of soil is controlled by stress strength.

Abstract: The landslide process and mechanism of rainfall-induced landslides are assessed by using particle flow code in two dimension based on the discrete element method. The formation mechanism of rainfall-induced landslide is revealed by the analysis of displacement field, velocity field and stress of the slope versus time. The fluid velocity and porosity of sample increase gradually with the increase of water head, the violent fluctuation of contact number of movable particles show the violent motion of slope, then the slope maybe slide.

Abstract: According to some actual cases of pile insertion analysis, combined with specialty norms and principles of soil mechanics in this paper, a few common misconceptions in pile insertion analysis of offshore platforms in Chengdao Oilfield are summarized. Type of common misconceptions, causes and adverse effects are analyzed, and countermeasures are put forward to correct misunderstandings and improve the accuracy of pile insertion calculation and analysis. Cases of analysis errors can be easily found because of unclear soil layer classification, difficultly recognized geotechnical properties, inaccurately divided layer uniformity, inadequately considered structure and soil interaction responses, etc. in offshore platforms pile insertion analysis, thus many unnecessary losses appear in oilfield production. By improving survey quality, using a variety of means of investigation, paying more attention to soil layer uniformity in well field, properly evaluating strength of laminated soil, doing anti-slip platform evaluation when pile is inserted too shallow, etc. can reduce errors effectively.

Abstract: It is mainly discussed that the minimum safe thickness of the stope roof and the ground subsidence deformation during mine excavation. The concrete method is deducing the theoretical calculation formula of minimum thickness of the stope roof according to the bending and shearing structural mechanics model respectively so as to gain the minimum safe thickness; A detailed engineering geological 3d model for mining concessions is built by using Auto CAD,and next a numerical calculation model is established by using ANSYS finite element software,following by importing it to numerical simulation software FLAC3D for calculation. By this method,the whole process of mine excavation can be simulated. Finally,the ground subsidence deformation obtained by simulation satisfies the specification requirements.

Abstract: Swell-shrinking, crack development and over-consolidation are the characteristics of expansive soil, and it is an over-consolidation soil undergone dry-wet cycles. So there may be some faults to analyze expansive soil slope stability adopting the traditional strength criterion and calculation methods. In this paper, triaxial tests were carried out to obtain the relations between the parameters of shear strength and generalized plastic shear strain. The soil shear strength increases and then decreases along with the increasing of shear deformation due to soil over-consolidation. Moreover, the residual strength is achieved finally. The functions are applied in simulating the relations between the parameters and generalized plastic shear strain in order to analyze expansive soil slope stability.

Abstract: Water is one of the most important factors affecting the mechanical properties of soil.Research on the intrinsic mechanism of soil by water effect is significant. In this paper, the mechanical properties of loess in Shanxi under different water content is studied from the experimental angle. The result shows that the stress of intact loess increases with the water content decreasing. Pressure failure stress increases with water content decreasing under the same confining, and amplitude reduction increases.Keywords: moisture content; physical properties; intact soil; confining pressure