基于加权双剪强度理论的高强井壁结构理想弹塑性解

为更方便获得高强井壁的极限承载力,基于加权双剪强度理论,考虑不同中间主应力效应,分2种情况分别求解厚壁圆筒的理想弹塑性解:①厚壁圆筒在外压p₀作用下处于全弹性状态,加上轴压P后处于弹塑性状态;②厚壁圆筒仅在外压p₀作用下处于弹塑性状态。得到了基于加权双剪强度理论的厚壁圆筒的弹塑性应力解公式、弹塑性极限承载力公式、塑性区半径表达式,并给出不同中间主应力的适用条件;对情况②中的极限承载力公式进行修正,给出了C70高强混凝土井壁极限承载力修正公式,用修正的极限承载力公式计算的高强井壁极限承载力与试验值相比,误差在±3%左右。修正的极限承载力公式将对井壁结构的优化设计具有重要指导意义。

Ideal Elasto-plastic Solution of High-strength Shaft Lining Based on Weighted Double Shear Strength Theory

An ideal elasto-plastic solution of thick-walled cylinder is presented to acquire the ultimate bearing capacity of high-strength shaft lining based on the weighted double shear unified strength theory in consideration of different intermediate principal stress effects. In one case, under external pressure p₀,thick-walled cylinder is in full elastic state, but changes to elasto-plastic state when axial compression P is applied; in another case, only under external pressure p₀, thick-walled cylinder is in elasto-plastic state. Moreover, the formula of elasto-plastic stress solution, the formula of elasto-plastic ultimate bearing capacity, and the expression of the radius of plastic zone are obtained based on the weighted double shear unified strength theory, and the applicable conditions of different intermediate principal stresses are given. The aforementioned formula of ultimate bearing capacity is modified for C70 concrete shaft lining. Compared with the test value, the error of the ultimate bearing capacity calculated by the modified formula is about ±3%. In summary, the modified formula of ultimate bearing capacity is of guiding significance for the optimal design of shaft lining structure and model test results.