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基于Hoek-Brown强度准则,推导了在微小转动下嵌岩段桩侧法向应力及水平摩阻力计算模型,采用静力平衡原理建立了水平荷载作用下公路桥梁桩基嵌岩深度的计算公式,提出了嵌岩深度计算的新方法。参数敏感性及影响因素分析表明:(1)水平荷载引起的力矩HM、桩径d、岩层上覆压力σv、岩石单轴抗压强度σc、岩体类别参数0m、岩体地质力学分类指标RMR均对嵌岩深度有一定影响,在HM、d不变的情况下,岩体质量和岩石单轴抗压强度对嵌岩深度的确定最为敏感;(2)岩体质量越差,所需嵌岩深度越大;岩体质量越好,岩层上覆压力对嵌岩深度影响越小,反之越大。(3)嵌岩深度随岩石单轴抗压强度的提高呈非线性缓慢地减小,在相同的单轴抗压强度下,岩体质量越好,嵌岩深度越小,反之越大。
Based on the Hoek-Brown strength criterion, the calculation model of normal stress and horizontal friction resistance of pile-socketed section under slight rotation is deduced. Based on the principle of static balance, the formula of rockfill depth of pile foundation of highway bridge under horizontal load is established, Proposed a new method of socketed depth calculation. The analysis of parameter sensitivity and influencing factors shows that: (1) The moment HM, pile diameter d, overburden pressure σv, uniaxial compressive strength σc, rock mass classification parameter 0m, rock mass geomechanics classification index RMR Both have an impact on the socketed depth. Under the condition of constant HM and d, the mass of rock mass and uniaxial compressive strength of rock are most sensitive to the socketed depth; (2) The greater the depth of the rock; the better the quality of rock mass, the smaller the influence of overburden pressure on socketed depth, and vice versa. (3) The depth of rock-socketed decreases nonlinearly and slowly with the uniaxial compressive strength of rock. Under the same uniaxial compressive strength, the rock quality is better and the rock-socketed depth is smaller, and vice versa.