基于桩-锚结构造价的锚索拉力计算模型研究

CALCULATION MODEL OF ANCHOR CABLE TENSILE FORCE BASED ON THE COST OF PILE-ANCHOR CABLE STRUCTURE

桩-锚结构的计算包括锚索拉力计算和桩身内力计算,通过锚索拉力计算桩身内力,再通过桩身内力计算结构造价,锚索拉力将影响桩-锚结构造价的计算,因此,锚索拉力计算对桩-锚结构设计尤为重要。通过对桩-锚结构造价与锚索拉力之间的关系进行分析研究,从桩-锚结构造价与锚索拉力的关系曲线、多项式拟合以及优化的变形协调条件3个方面建立与桩-锚结构造价相匹配的锚索拉力的计算模型。结合桩身内力计算的"m"法和"K"法以及结构力学中的虚功原理和图乘法理论,编写Visual C++计算程序,通过不同的滑坡工程实例对不同锚索拉力作用下的桩-锚结构造价进行计算,获得锚索拉力与桩-锚结构造价的关系图。计算结果表明:桩-锚结构造价是随着锚索拉力的增大先减小后增加的。关系曲线模型和多项式拟合模型计算的与桩-锚结构最低造价相匹配的锚索拉力与优化的变形协调条件计算的锚索拉力十分接近,可选择其中任意一种计算方法计算得到的锚索拉力作为最终锚索拉力计算值。此时,桩身弯矩的正负极值并不相等,这也表明桩身正负弯矩的极值相等时的锚索拉力并不一定是最优的锚索拉力,因为此时桩身所处的受力状态虽然比较理想,但造价可能较高,经济效益不佳。

Designing of pile-anti-slide with anchor cable includes anchor cable tensile force and pile internal force.Pile internal force can be obtained by anchor cable tensile force. The cost of pile structure can be obtained by pile internal force. Then anchor cable tensile force affects the cost of pile-anchor cable structure. Therefore,anchor cable tensile force computing is especially important in the design of pile-anchor cable structure. This paper analyzes and studies the relationship between the cost of pile-anchor cable structure and anchor cable tensile force.It establishes anchor cable tensile force matching with the cost of pile-anchor cable structure calculation models from three aspects of relation curve model,polynomial fitting model and optimized deformation consistence conditionmodel. It combines'm'and 'K'methods of pile internal force calculation and structural mechanics' principle of virtual work and diagram multiplication method. A calculation programs by Visual C++is complied to calculate the cost of pile-anchor cable structure with different anchor cable tensile force through different case studies. It presents the relation diagrams between the cost of pile-anchor cable structure and anchor cable tensile force. The results show that the cost of pile-anchor cable structure first decreases and then increases with the increase of anchor cable tensile force. Three kinds of model calculation results of anchor cable tensile force matching with the cost of pileanchor cable structure are very close. Anchor cable tensile force calculated by any method can be considered as the final anchor cable tensile force design value. At this point,the plus and minus extremums of bending moment of pile are not equal. This also shows that anchor cable tensile force is not necessarily the optimal when the plus and minus extremums of bending moment of pile are equal. Although pile body status is ideal at the moment,the cost may be higher,so that economic benefit is poor.