无底圆筒结构内填土压力分布和抗倾有效比计算

由于无底圆筒结构与有底结构相比,在结构沉降、基底应力等方面存在差异,导致二者的内填土压力分布明显不同,因此,传统的贮仓压力理论不能正确确定无底圆筒结构的筒内填土压力．采用模型试验,量测作用在无底圆筒结构上的土压力,分析无底圆筒结构与内填土和地基的相互作用,探讨圆筒结构在倾覆过程中内填土与筒壁间摩阻力调整机理．通过试验研究和理论分析得到,在对称荷栽作用下筒内土压力分布分为三个区域,在非对称荷栽作用下,由于筒内产生附加力矩而使土压力分布变为两个区域,且抗倾有效比约为对称荷栽状况下的1．10倍,在此基础上,提出了对称荷栽和非对称荷栽(作用有侧向荷载)情况下,筒内填土压力和抗倾有效比的计算方法,前者适用于圆筒施工期的计算,后者适用于使用期的计算．

Distribution of Inner Soil Pressure Acting on Open Bottom Cylindrical Structure and Calculation of Effective Anti-Overturning Ratio

The settle and base stress of the open bottom cylinder differ greatly from those of the closed bottom structure.As a result,their distributions of inner soil pressure on the open bottom cylindrical structure are obviously different. Hence,the traditional theory used for calculating the pressure of stored material in silos is not suitable for determining the inner soil pressure of open bottom cylinder.By investigating the inner soil pressure on the open bottom cylinder, which is obtained from the model experiments,the interactions among the filler inside the cylinder,subsoil and cylinder are analyzed.The adjusting mechanism of frictional resistance between the inner filler and all of cylinder during overturning of the cylinder is discussed.It is obtained that the distribution of inner soil pressure may be divided into three regions,i.e. active region,transitional region and compressive region under axisymmetric loading, and the regions can be changed as the additional moment inside the cylinder is generated during overturning of the cylinder, in which case, the effective anti-overturning ratio is 1.1 times larger than that under axisymmetric loading.Based on the experimental study,a method for calculating the inner soil pressure on the cylindrical structure under axisymmetric loading or non-axisymmetric(with lateral)loading is proposed.The method for axisymmetric loading is applicable to cylindrical structure under construction and the method for non-axisymmetric loading is applicable to cylindrical structure in operation.Meanwhile,the effective anti-overturning ratio of the open bottom cylinder is derived.