Advanced Materials Research Vols. 243-249

Abstract: Squeezed branch pile is based on the traditional uniform pile in development of a new type of pile, with a high bearing capacity, settlement of small features widely used in the engineering. Based on the actual project site static test, analyzed the vertical bearing capacity characteristics of two adjacent squeezed branch piles; By means of testing of the pile stress gauge steel embedded in different parts of piles, the axial force transfer characteristics of the body, support plate side resistance drag and play characteristics of the squeezed branch pile were analyzed. The results showed that: the branch pile Q-S curve is slowly varying type, the three branch share of the load ratio increases with the pile top load increases and then decreases, load sharing ratio of 12% or so. The side resistance increased with the pile top displacement, the curve showed significant enhancement traits. Measured friction value of two test piles is too conservative under the existing norms, the actual measured value of 1.2～1.6 times of the standardized value.

Abstract: The bearing capacity property of large-diameter bored cast-in-situ deep and post-grouting pile is analyzed on the basis of measuring data of static load test and axial stress measure data. The study indicates that the large-diameter bored cast-in-situ deep and post-grouting pile show the characteristics of the friction when the bearing course at pile end is sand, when the pile top load is greater than 18000kN, the pile end begin to resistance and the share proportion is small, only 1% to 10%; the load settlement cure is gradual decline, no inflection point, the settlement of pile compression only accounted for about 15%, The developing degree of side resistance is well corresponding to the relative displacement between pile and soil. The side resistances significantly enhance effect, the measured value of the soil side resistance is 1.3 to 1.5 times of survey report recommended.

Abstract: The authors conducted research aimed at developing a new type of permeable concrete material with enhanced structural strength. This paper presents and discusses the results of their investigation on the unaxial compressive stress-strain relationship of porous concrete made with two different mix designs with constant water to cement ratio. The concrete mixes were designed with a target compressive strength between 15-25 MPa and target porosity between 10-15% to study the effect of pore sizes on the stress-strain curve. The average pore space was increased by increasing the relative amount of large aggregate. The reduction in the relative amount of fine aggregate increased the average pore space and resulted in a reduction in mix stiffness and a marginal increase in ultimate strength.

Abstract: The rockfall trajectories are affected by many kinematic parameters. So it is very necessary to exactly analyze the sensitivity of rockfall kinematic parameters to the control indices for design of protective structures. In this paper, the kinematics combined with the orthogonal test is adopted to analyze the sensitivity of rockfall kinematic parameters. Taking the rockfall hazard near the DK27+120 section of the jing-ying expressway in china for example, three control indices are taken as the testing indices, and five kinematic parameters are taken as the testing factors. The orthogonal test table is used to design twenty-five kinds of schemes, and the numerical simulation tests of rockfall trajectories are carried out. The range analysis are performed to study the sensitivity of rockfall kinematic parameters, and then the main parameters influencing the control indices for design of protective structures are obtained, which provides scientific basis for the rockfall prevention in jing-ying expressway.

Abstract: With Yichang-Wanzhou Railway project being taken into account, this article systematically analyzes the control factors of geological hazard in tunnel construction including stratum, lithology, fold, rupture and groundwater seepage,etc, establishes hazard assessment index system, and induces the underlying principle and methods of index assignment. On the basis of the theory and technology of expert system, this article develops an intelligence analysis system for karst water inrush geological hazard risk assessment in tunnel construction, explores the construction method of karst water inrush geological hazard expert system and the implementation of software platform, and takes Qiyueshan Tunnel as an example to make the research of engineering application.

Abstract: The genesis of Xi’ an ground fissures and the recent activity characteristics and tendency have been introduced firstly. The architectural damage caused by ground fissures and current hazard prevention methods have been described secondly. The applications of a new material used in controlling underground engineering and coal mine disaster have been introduced. The mechanical properties of the new material have been stated also. As a result, a new foundation treatment method has been envisaged to make it possible to construct architectures on ground fissures.

Abstract: This paper verified effect and feasibility by indoor model test of using drainage of vacuum preloading method and electro-osmosis method to reduce water content of saturated over-wet soil in moist and rainy areas. The results showed that: both methods could effectively reduce water content of saturated over-wet soil in Ya’an area, to achieve the desired effect of drainage and consolidation. Neither spatial distribution of level of reducing water content was obvious.

Abstract: In order to understand the dynamic stress diffusion rule of the waste iron slag (sand soil) during dynamic consolidation, we conducted a large field test. The propagation and attenuation of dynamic stress in each ramming strike was recorded through the resistance strain gauge. It was shown that the dynamic stress caused by dynamic consolidation is pretty obvious. The dynamic stress dissipates extremely fast during the dynamic consolidation, the time is only 0.5s after plus the aftermath. The soil dynamic stress has heart-shaped distribution during the compaction. The dynamic stress value increases with the tamping hit number, but it keeps stable after about the third hits.

Abstract: This article is based on the Bazimen Landslide in the three gorges reservoir area to be the object of study, and uses the Boussinesq unsteady aeolian-equation to calculate the change of the infiltration line in the landslide by the reservoir water decreased and rainfall. The limited equilibrium method is taken to study the variation law of the landslide stability, which is effected by the every factor under different working conditions.

Abstract: In addition to the gas tunnel in coal strata, there are a large number of gas tunnel in non-coal strata, these tunnels itself do not through the coal strata, but all encountered the gas problem in the construction process. Because of not a full understanding and preparation on gas of tunnel in non-coal strata zones, and the gas emission is random, uneven distribution of the characteristics, so the gas disaster hazard is larger in such gas tunnel, study on its formation mechanism is great significance. Based on the study of a lot of the gas tunnel has been constructed, summed up three genetic types of the non-coal strata gas tunnel: one type is structural connectivity, according to the different structure types, can be divided into fracture connectivity type, fault type and fold connected connectivity type; Second is surrounding rock metamorphic type; third is compound effects type.