深层基础也许是支持结构的最强大选择。当然，还有其他选项 - 浅基础（传播基础），中间基础（聚合码头）和地面改进方法 - 但没有人在自己的权利上令人印象深刻，或者像堆一样携带负荷。此外，桩在他们自己的房间里提供了如此多的选择讨论了其他任何东西。
深度基础比我们只能处理一个博客文章。万博app手机版官网下载因此，在我们博客系列的第一部分中，我们将讨论不同类型的深层基万博app手机版官网下载础，其中一些在设计它们中。第2部分将解决质量控制和完整性测试 - 换句话说，建设。
什么是深层基础，何时使用？
Deep foundations (generically referred to as piles) are long, slender, structural elements that transfer the load from a structure (building, bridge, embankment, etc.) through supporting media or to a supporting medium (soil and/or rock) at depth. Geometrically, a deep foundation can be defined as having a length (depth of embedment) significantly greater than its width.
深层基础可以钻，驱动，拧入或推入地面。在某些情况下，它们实际上是用手或典型的土方设备挖掘，然后用混凝土铸造以填补挖掘。由于许多原因使用深层基础。最常见的包括：
- 渗透相对较弱，近曲面的土壤
- 穿透高度可压缩的土壤，例如有机物或深度弱粘土
- 渗透深，污染，近地面土壤
- 渗透深，不受控制的填充
- 适应大量负荷
可以根据其目的，类型，施工方法，位移或容量在许多方面对深度基础进行分类。下表不是详尽的清单，但确实涵盖了中西部最常见的深基础类型。除了材料强度和直径之外，典型的负载能力也因现场的地下条件而变化。这一概念引领我们对深层建立的设计。
深基础设计
如今，大多数深层基础设计方法都由联邦公路管理局（FHWA）发表，他拥有进行研究和现在的资源。承包商和材料供应商还推进了深基础设计，通常通过各种基于行业的社会或团体。
在概念上,rela是深基础的设计tively simple. The sides of the pile provide resistance to load through friction between the pile and the soil it penetrates. The bottom of the pile provides resistance to load through bearing like a typical spread (shallow) footing. However, the mechanics at work are more complex in practice, especially due to the nature of soil and rock behavior and the inherent variability of soil and rock. When you add tension, movement and lateral loads to the compression loads that a pile supports, the evaluation of a pile’s capacity and the selection of the right pile type becomes more difficult and iterative.
深基础设计始于了解项目现场的地下条件，以及关于建立的内容的知识，性能预期和风险容忍度。建立了地下条件和建筑物载荷后，可以根据安装是多么容易或困难的方式选择适用的设计桩类型。例如，驱动的桩或螺旋铸造桩可能不适合于轴承土壤含有鹅卵石和巨石与弱甚至称重的土壤混合的网站。同样地，钻孔轴可能不是污染土壤的座位的最佳选择，轴的处置是潜在的昂贵且困难的。
在识别合适的桩类型之后，下一步骤是评估不同桩类型的侧面和端轴承电阻以及长度，宽度和直径的范围。该评估包括开发地下条件的模型，并分配土壤或岩石强度参数，影响不同类型桩的摩擦或承载能力。
通过开发的模型，我们接下来考虑桩对桩的不同极限状态，例如轴向压缩和张力的强度，或沉降和横向偏转。然后根据满足性能所需的限制状态评估，桩尺寸，长度或强度以及项目的风险要求，根据限制状态评估，桩尺寸，长度或强度进行调整。
Although it has most likely been going on throughout the previous steps, communication with the project team (the owner, structural engineer and contractor) now reaches a critical point. The team needs to evaluate the costs and performance of the different pile types.
At Braun Intertec, we like to look at load-support cost, which is the cost of an installed pile divided by the allowable load of the pile. This is different from comparing the cost per foot of different pile types or sizes. Sometimes, it is more cost-effective to install fewer, longer piles than it is to install more, shorter piles. Depending on the outcome of the discussion, the group may choose to consider additional pile types or sizes or eliminate some from consideration. Hopefully, the team is able to identify the perfect pile type and size and can move to the next step of the process, construction, which we will discuss next week in第2部分。