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偏压隧道结构稳定性评价的信息优化分析 总被引:24,自引:4,他引:24
将影响偏压隧道结构稳定性的因素概括为4个指标,即围岩超欠挖量,隧道稳定性系数,地震烈度和隧道偏压比。然后对每个指标收集若干组原始数据信息。利用原始数据,根据信息优化理论建立原始数据信息与偏压隧道结构稳定性关系,对结构稳定性进行评价,经过计算分析和工程检验,证实了该方法的可靠性。 相似文献
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According to the interaction of three shallow tunnels with large section, the analytical solution to rock pressure has been derived and discussed. The load model is given when the bilateral tunnels are excavated. According to the model, the stresses of three tunnels and single tunnel are calculated and compared to analyze the distribution characteristics, where the stresses are influenced by controlling factors of clear distance, covering depth and inclination angle of ground surface. The results show that, in general, the bias distribution is more serious. Therefore, it is significant to settle down the load model of three shallow tunnels so as to determine the measure of reinforcement and design the structure of support. The model and results can be used as a theoretical basis in designation and further research of the three shallow tunnels. 相似文献
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Displacement and deformation analysis for uplift piles 总被引:1,自引:1,他引:0
On the assumptions that the shear resistance increases linearly with increasing shear displacement between the uplift pile and surrounding soil, that the axis force is distributed as parabola along the pile length, that elastic distortion occurs when the pile is loaded, that the displacement of pile is in accord with that of the soil, and that the uplift pile failure is regarded as the soil failure, a rational calculation method was proposed for calculating the deformation, ultimate displacement and shear resistance of piles. The distributions of frictional resistance and the shear displacement along the pile length were obtained with the method. The comparisons were made between the measurement results and the present results. The present theoretical results agree well with the measurement results, with the average difference being less than 12% before failure. The comparisons show that the proposed method is reasonable for uplift design and engineering construction of piles. 相似文献
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Pile-soil stress ratio in bidirectionally reinforced composite ground by considering soil arching effect 总被引:1,自引:0,他引:1
To discuss the soil arching effect on the load transferring model and sharing ratios by the piles and inter-pile subsoil in the bidirectionally reinforced composite ground, the forming mechanism, mechanical behavior and its effect factors were discussed in detail. Then, the unified strength theory was introduced to set up the elastoplastic equilibrium differential equation of the subsoil under the limit equilibrium state. And from the equation, the solutions were derived with the corresponding formulas pres... 相似文献
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Stability analysis of shallow tunnels subjected to seepage with strength reduction theory 总被引:2,自引:1,他引:1
Based on strength reduction theory, the stability numbers of shallow tunnels were investigated within the framework of upper
and lower bound theorems of limit analysis. Stability solutions taking into account of water seepage were presented and compared
with those without considering seepage. The comparisons indicate that the maximum difference does not exceed 3.7%, which proves
the present method credible. The results show that stability numbers of shallow tunnels considering seepage are much less
than those without considering seepage, and that the difference of stability numbers between considering seepage and without
considering seepage increase with increasing the depth ratio. The stability numbers decrease with increasing permeability
coefficient and groundwater depth. Seepage has significant effects on the stability numbers of shallow tunnels. 相似文献
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Influences of nonassociated flow rules on seismic bearing capacity factors of strip footing on soil slope by energy dissipation method 总被引:2,自引:3,他引:2
Seismic bearing capacity factors of a strip footing placed on soil slope were determined with both associated and nonassociated flow rules. Quasi-static representation of earthquake effects using a seismic coefficient concept was adopted for seismic bearing capacity calculations. A multi-wedge translational failure mechanism was used to obtain the seismic bearing capacity factors for different seismic coefficients and various inclined angles. Employing the associated flow rule, numerical results were compared with the published solutions. For bearing capacity factors related to cohesion and equivalent surcharge load, the maximum difference approximates 0.1%. However, the difference of bearing capacity factor related to unit weight is larger. With the two flow rules, the seismic bearing capacity factors were presented in the form of design charts for practical use. The results show that seismic bearing capacity factors related to the cohesion, the equivalent surcharge load and the unit weight increase greatly as the dilatancy angle increases, and that the nonassociated flow rule has important influences on the seismic bearing capacity. 相似文献
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The analytical solutions for predicting the exact shape of collapse mechanisms in shallow tunnels with arbitrary excavation profiles were obtained by virtue of the upper bound theorem of limit analysis and variation principle according to Hoek-Brown failure criterion. The seepage force was included in the upper bound limit analysis, and it was computed from the gradient of excess pore pressure distribution. The seepage was regarded as a work rate of external force. The numerical results of roof collapse in square and circular tunnels with different rock parameters were derived and discussed, which proves to be valid in comparison with the previous work. The influences of different parameters on the shape of collapsing blocks were also discussed. 相似文献