Chapter 2 Bearing capacity of foundation In lesson of soil mechanics,we've learned Types of foundation failures(基础破坏的类型 Ultimate bearing capacity of shallow Foundations (浅基础地基极限承载力 Prandtl's method: :smooth foundation and weightless soil(普朗特公式：基底光滑与 润 尤重量 Terzaghi's method:rough foundation(太沙基 公式：基底粗糙 超
Chapter 2 Bearing capacity of foundation In lesson of soil mechanics, we’ve learned ▪ Types of foundation failures (基础破坏的类型) ▪ Ultimate bearing capacity of shallow Foundations (浅基础地基极限承载力) ▪ Prandtl’s method: smooth foundation and weightless soil (普朗特公式:基底光滑与土 无重量) ▪ Terzaghi’s method: rough foundation (太沙基 公式:基底粗糙)
2.1 Introduction(前言) Ultimate bearing capacity (q)is defined as the pressure which would cause shear failure of the supporting soil immediately below and adjacent to a foundation. 压力增大到极限承载力时，地基出现剪切破坏) A foundation must satisfy two fundamental requirements: 计基础要两足两个婆求) the factor of safety Fs against shear failure of the supporting soil must be adequate,a value between 2 通 and3 normally being specified(地基达到剪切破坏的 全系数F。要适当， 般在2至3乙间 超
2.1 Introduction (前言) ▪ Ultimate bearing capacity (qu ) is defined as the pressure which would cause shear failure of the supporting soil immediately below and adjacent to a foundation. (当基底 压力增大到极限承载力时,地基出现剪切破坏) ▪ A foundation must satisfy two fundamental requirements: (设计基础要满足两个要求 ) ▪ the factor of safety Fs against shear failure of the supporting soil must be adequate, a value between 2 and 3 normally being specified (地基达到剪切破坏的 安全糸数 Fs要适当,一般在2至3之间 )
2.1 Introduction(前言) the settlement of the foundation should be tolerable and, in particular,differential settlement should not cause any unacceptable damage of the structure(基础的沉降和元 降差必须在该建筑物所允许的范围之内)「 Allowable bearing capacity (q)is defined as the maximum pressure which may be applied to the soil such that the above two requirements are satisfied.From first requirement, qa is defined as:(地基的容许承载力q定义为当上述两 亲件满足时的基底最大压力.当条件满是时9。定义 如下 qu qa
2.1 Introduction (前言) ▪ the settlement of the foundation should be tolerable and, in particular, differential settlement should not cause any unacceptable damage of the structure (基础的沉降和沉 降差必须在该建筑物所允许的范围之内) ▪ Allowable bearing capacity (qa ) is defined as the maximum pressure which may be applied to the soil such that the above two requirements are satisfied. From first requirement, qa is defined as: (地基的容许承载力 qa 定义为当上述两 个条件满足时的基底最大压力.当条件一满足时qa 定义 如下) s u a F q q =
2.2 Types of foundation failures(基础破坏类型) (i)General shear failure(整体剪切破坏) State of plastic equilibrium is fully developed throughout the soil above the failure surfaces(地基形成 实滑动围而破场 Heaving of the ground surface occurs(甚础两侧地面向L隆起 Typical failure mode for soils of low compressibility,i.e.dense or stiff soils(紧砂或硬粘士的典型破坏模式 图 Pressure Ground surface (地面) Sliding surface (滑动面)
2.2 Types of foundation failures (基础破坏类型) (i) General shear failure (整体剪切破坏 ) ▪ State of plastic equilibrium is fully developed throughout the soil above the failure surfaces (地基形成连续滑动面而破坏) ▪ Heaving of the ground surface occurs (基础两侧地面向上隆起) ▪ Typical failure mode for soils of low compressibility, i.e. dense or stiff soils (紧砂或硬粘土的典型破坏模式) Pressure Settlement Sliding surface (滑动面) Ground surface (地面)
2.2 Types of foundation failures(基础破坏类型) (i)Local shear failure(局部剪切破坏) Partial development of the state of plastic equilibrium 破坏区限制在地基内部某一区域 Slight heaving occurs(基础两侧地i只是微微隆起) It is characterized by the occurrence of relatively large settlements(这种破坏型式的情征是出现相对木的沉降 Pressure I Ground surface (地面) Sliding surface (滑动面)
2.2 Types of foundation failures (基础破坏类型) (ii) Local shear failure (局部剪切破坏) ▪ Partial development of the state of plastic equilibrium (剪切 破坏区限制在地基内部某一区域) ▪ Slight heaving occurs (基础两侧地面只是微微隆起) ▪ It is characterized by the occurrence of relatively large settlements (这种破坏型式的特征是出现相对大的沉降 ) Pressure Settlement Sliding surface (滑动面) Ground surface (地面)