Advanced Materials Research Vols. 671-674

Abstract: The new constructing railway Haerbin-Dalian Dedicate Line runs through the typical seasonal frozen region. For the purpose of estimating the quality of subgrade construction, a field test was played. Placed the monitoring instrument and measure the soil temperature, settlement and soil pressure etc.. The monitoring data shows that the change of soil temperature is less than the environment temperature. The maximum frost depth is 1.66m. In this depth, the fine-grained soil with high frost-heave characteristic should not be as the subgrade. The effective measure to prevent the rain percolated through the subgrade is important. And the filling of subgrade should be constructed strictly according to the maximal degree of compaction and keep the best water content. The settlement of subgrade is less than 15mm, the water content is also less than the prime frost-heave water content and the frost-heave force is very small. Thus, the construction technique subgrade is feasible.

Abstract: One of the main failure forms of inner bond section for prestressed anchorage structure is the failure of interface between the rock mass and the grouting body, so this interface is usually one of the weak link of the whole anchorage system, and so it is important to analyze the failure developing law of the interface. Based on the finite difference program FLAC3D, the numerical analysis model of inner bond section for prestressed anchorage bolt was built, and the failure developing laws of inner bond section under step loading were studied from three aspects: displacement change, shear stress change and yield point position change. The influence of the change of inner bond section length and the grouting body strength on the inner bond section failure developing law was also analyzed. At last, compared with the results of indoor static load test, the reliability of the numerical simulation was certified.

Abstract: Pit excavation has a negative impact on the existing shield tunnel close to it. The deformation mechanism of the existing tunnel during the pit excavation was analyzed. Theoretical analysis results shows: excavation unloading decreases the pressure in horizontal direction of the tunnel, which causes tunnel taking the horizontal displacement to the pit side; convergent deformation keeps in horizontal stretching, vertical compression, but the deformation is aggravated; tunnel vertical uplift or settlement is determined by the pit excavation depth; precipitation would make tunnel sinking. Five domestic pit excavation engineering instance was collected, and the reliability of the analysis in this article is proved by the statistical analysis of the measured data.

Abstract: The landslide is a global geological disasters, causing casualties and huge economic losses. This paper, the Dalian Xinghai Zhong Long Yuan landslides treatment project, analysis of landslides generated by internal causes and predisposing factors, obtained a landslide failure mechanism, and the causes of slope cutting, improve cut flood drainage structures, prestressed anchor Mississauga solid technical measures. The construction process for top of the hill horizontal displacement, deep horizontal displacement and anchor bearing capacity monitoring results show that the landslide control program is correct and effective measures to achieve the desired effect, made landslides governance success to reference for landslide control work for the Dalian region and the coastal cities.

Abstract: There are many in situ stress measurement methods nowadays, the ISRM suggested two methods for in situ stresses measurement: overcoring methods and the hydraulic fracturing methods. In order to study the distribution law of in situ stress field in the deep position of Hongyang coal mine, 3 points of in situ stress measurement were carried out in underground roadways at the -870 m level adopting the overcoring method. The KX-81 type gauge was used to measure the 3 points of in-situ stress. According to the analysis and calculation of the measurement data, the result showed that the in situ stress field in Hongyang coal mine at the depth of -870m was dominated by horizontal tectonic stress.

Abstract: Base on the shaft construction of a subway station in Changchun, make a detailed analysis of the site monitoring data of the retaining structure and the ground surface settlement against the excavation process of the inverted side wall shaft. By using the FLAC-3D software of finite difference, the numerical simulation are conducted, thus, make a comparison with the site monitoring data, and summarize the deformation characteristics of the retaining structure and the surface deformation of the inverted side wall shaft during the excavation. Results show that the support of the inverted side wall shaft which adopting alternation excavation and supporting while excavating has good stability, and the monitoring result is close to the numerical simulation’s, which provides the basis for the success of the engineering.The research results can be references for other similar designs and constructions.

Abstract: Static liquefaction is one of the main causes of flow slide destruction in tailings pond. This paper analyzed the static liquefaction behaviors in tailings pond through the development of displacement, deformation and pore pressure ratio. Based on the simulation results, some conclusions were obtained. Fast discharge of tailings will fasten the increase of pore pressure. The dam-toe in tailings pond is very easy to be eroded, leading to introverted destruction. The liquefaction of sand layer in foundation would cause the tailings dam’s slip failure. With the arising of tailings, pore pressure increased continuously expanding to the foundation under the dam.

Abstract: In order to analyze slope stability of coal gangue dump in Shanxi Zhangcun, an in-situ push-shear test was carried out to obtain the shear strength indexes of gangue dump and it has been found that soil on top of slope possesses with larger strength than that on the hillside due to natural stacking interaction. Finite element calculation was also built to find that the plastic zone of gangue dump runs through clay layer on foot of dump. This means soil condition plays an important role in slope stability. Single index and multi factors were selected for orthogonal test design. Safety factors of slope stability were evaluated according to finite element strength reduction. Multi-factor sensitivity analysis has been conducted with the result that sensitivity of density of soil, angle of internal friction, angle of slope and cohesion to safety index of slope stability are progressive reduced.

Abstract: In order to study the safety mining of the deep buried coal seams being threatened by high pressure karst water, relative impermeability of the Ordovician top is demonstrated through studying lithology，filling degree of the karst fissures as well as wash water quantity, in the Baode mine field. Furthermore, the main influencing factors on impermeability of coal seam floor are analyzed, and divisional risk assessment of floor water-inrush from the Ordovician karst aquifer is performed. Overall，by considering the relative impermeable strata in the Ordovician top, the accuracy of risk assessment on coal floor water-inrush can be improved.

Abstract: The paper introduces the basic principles of vertical bearing capacity of the pile by using static load test, establish the random site theory model of the bearing capacity of prestressed pipe pile foundations calculation, calculates and statistics the try count ratio of vertical bearing capacity of 144 prestressed pipe pile in Tianjin, work out calculation procedures of JC method, calculate reliability index of vertical bearing capacity and analyze calculation results. In the last, we build a model using the finite element software, analysis the displacement of pile top under earthquake, evaluates the horizontal bearing capacity of prestressed pipe pile.