Abstract: The slope of loess high embankment stability analysis is in northwest loess area highway construction important question, also is in the crag earth project discipline one of most ancient model research topics. This article folds the subtraction analysis loess high embankment stable question with the strength reduction FEM, not only can direct—viewing see the soil body stress strain the development change, moreover may obtain the slope and stability the coefficient. This article folds the subtraction obtained stability coefficient with the strength reduction FEM to be smaller than the bishop law obtained stability coefficient.
Abstract: Applying combined surface,the graphical method is used to calculate the passive earth pressure usually. Not only procedure of the graphical method is complicated but also its precision is poor. Based on the principle of the circular combined surface and methods of mathematics and mechanics method ,a formula of passive earth pressure on cohesive soil,which can be applied to the trial calculation by programming procedures,is proposed. The case analysis shows that the calculated results are the same as those calculated by the Coulomb theory under the conditions of the smooth vertical wall back; In the small,there is slight difference between the two; But with the increase of,the calculated results of Coulomb theory are significantly greater than those calculated by the method. Therefore, in a greater external friction anglebetween the wall and the backfill, it should use the method which optimizes the engineering design and reduces project cost.
Abstract: Application and research of GIS in the slope engineering is one of the hot topics in this field. In this paper, the fuzzy comprehensive evaluation method of slope stability based on GIS was researched. It developed and set up a multi factor slope fuzzy comprehensive evaluation system by using slope database and can quantitatively classify and evaluate the slope stability in a quick and efficient way. This system can be at work on slope data management, inquiry, statistics and spatial analysis. It evaluated the fatality and vulnerability to the slope of a large scale coal mine as an example.
Abstract: During the tunnel excavation in Zhang-Shi Expressway 2nd-Stage Project, rock burst phenomenon has occurred. Limy dolomite obtained from tunnel rock burst area is used to conduct laboratory loading rock burst test with simulation system of deep rock burst. Simultaneously, based on Particle Flow Theory and PFC3D program, a load-unload code is developed by fish language embedded in PFC3D to carry out simulation of laboratory loading rock burst test. Laboratory test result shows that the rock burst type and intensity of specimen are lagged and severe, respectively; During the test process, a spot of particles eject from the exposed surface; Obvious slabbing phenomenon can be seen on the exposed surface and the separate face of rock slab is parallel to the direction of maximal load σ1 as consistent with the actual phenomenon of engineering rock burst. In the loading rock burst simulation, the load grade, stress-step curve and failure mode of rock burst are almost consistent with the laboratory test. This simulation method describes the failure process actually and subtly, and reveals that the specimen fracture mechanism of loading rock burst is tensile type. Finally, some differences between loading and unloading tests of rock burst are discussed.
Abstract: Based on laboratory model test, this paper presents the draining efficiency of vacuum pre-loading method and electro-osmosis method with over-wet soil in moist and rainy areas. The results show that: both methods can effectively reduce the water content of saturated over-wet soil in Ya’an area, to achieve the desired effect of drainage and consolidation; and the degree of the effects of both methods differ with spatial variation.
Abstract: Based on eight groups of uplift tests for screw anchors with different embedded depths and different plate sizes, a method is given to compute the bearing capacity of screw anchor within critical depth in coarse sand according to analysis on force transmission route and failure characteristics. Within critical depth, bearing capacity of screw anchor is proportionate to embedded depth and the area of screw plate, and the failure surface is inverse triangle in shape. Beyond critical depth, the bearing capacity of screw anchor won’t increase with depth, and the failure surface is funnel in shape. Critical depth is about 10 times the diameter of screw plate. In both cases, the include angle between failure surface and the vertical plane equals to 0.5 time the friction angle of the soil.
Abstract: A lot of investigations showed that unstable rock masses (URM) could be classified into four failure modes：whole slide，rock block landslide，whole shear fall，and compress-rip-slide. Unloading cracks forming URM failure boundary don¢t store water usually，so the main loads to cause URM failure in dam region are weight and earthquake force. According to limit equilibrium theory, Authors put forward different calculation method of stability and criterion of stability state class to different failure mode. The corresponding treatments and cure to URM of different scale and stability state are presented, too.
Abstract: The mechanical properties of discontinuity are different from those of a whole rock. And the shear strength of discontinuity is closely related to its morphological characteristics. The study of the mechanism of failure of jointed rock mass under shear stress is to reveal its mechanical behavior and its mechanism of failure. This paper presents a fundamental research in the mechanical properties of the regular jugged discontinuity under various normal stresses in the shear test. And it describes the mechanical properties of the regular jugged discontinuity under shear stress and their principal regularities. The strength and roughness of discontinuity under shear stress are investigated by the analysis of the data obtained. And this paper study the calculation of shear stiffness of discontinuity and proposed an empirical formula between the slope ratio and roughness coefficient of discontinuity. Also the changing regularity of the parameters of the shear strength of discontinuity under shear stress is investigated, and an empirical formula is developed to evaluate the shear strength of discontinuity in this paper.
Abstract: The swelling behaviour of compacted expansive soils have been studied with variation in initial state. For comparison, a series of swell and shrinkage capacity laboratory tests with different initial dry densities，moisture contents and pressures have also been made with three different consistency state. Both percent swell and shrinkage are significantly influenced by the consistency state index. There is an unique relationship between percent swell and consistency state index of the soil. The percent swell-load relationship could be identified as a logarithmic relationship facilitating the prediction of ultimate percent swell under different load with a few initial results.
Abstract: An expression for slope stability and safety factor is established herein by using inclined slice method based on limit equilibrium condition theory. A limit state function for the reliability analysis of slope stability is established as well. Such analysis is carried out by using the Monte Carlo method so as to study effects of random variables of soil parameters such as adhesive force, internal frictional angle and average values of soil density, together with their coefficients of variation, on reliability index of soil. As demonstrated by the examples described herein, these coefficients of variation are linear with the reliability index β, which indicates that soil of low discreteness is available with high reliability index and vice versa. As such, the analysis by using the Monte Carlo method can provide theoretical basis for determination of stability of soil and thus is highly practicable in actual engineering and construction.