All structures designed to be supported by the earth, including buildings, bridges, earth fills, and earth, earth and rock, and concrete dams, consist of two parts. These are the superstructure, or upper part, and the substructure element which interfaces the superstructure and supporting ground. In the case of earth fills and dams, there is often not a clear line of demarcation between the superstructure and substructure. The foundation can be defined as the substructure and that adjacent zone of soil and/or rock which will be affected by both the substructure element and its loads.

所有支承在地基上的結(jié)構(gòu)物，包括建筑物、橋梁、土堤以及土壩、土石壩、混凝土壩都是由兩部分組成的。它們是上部結(jié)構(gòu)，或者說上面部分，和介于上部結(jié)構(gòu)與支承地基之間的下部結(jié)構(gòu)構(gòu)件。就土堤和各種壩而言，在上、下部結(jié)構(gòu)之間通常沒有一條明顯的劃分線?！盎A(chǔ)”這個名詞可以被定義為下部結(jié)構(gòu)及其鄰近的土和/或巖石，這些土或巖石既受到下部結(jié)構(gòu)構(gòu)件的影響，也受到荷載的影響。

The foundation engineer is that person who by reason of experience and training can produce solutions for design problems involving this part of the engineered system.?In this context,?foundation engineering can be defined as the science of applying the principles of soil and structural mechanics together with engineering judgment to solve the interfacing problem. The foundation engineer is concerned directly with the structural members which affect the transfer of load from the superstructure to the soil such that the resulting soil stability and estimated deformations are tolerable. Since the design geometry and location of the substructure element often have an effect on how the soil responds, the foundation engineer must be reasonably versed in structural design.

基礎(chǔ)工程師是能夠根據(jù)經(jīng)驗和所受的訓練對涉及這一部分工程系統(tǒng)的設(shè)計問題提出解決方案的人員。由于這個原因，基礎(chǔ)工程則可以定義為運用土力學與結(jié)構(gòu)力學原理和工程判斷來解決交界面問題的科學。基礎(chǔ)工程師所直接關(guān)心的是影響上部結(jié)構(gòu)向地基傳遞荷載的那些結(jié)構(gòu)構(gòu)件，以使地基穩(wěn)定性及預估變形量都在容許范圍以內(nèi)。由于下部結(jié)構(gòu)構(gòu)件的設(shè)計幾何尺寸及位置常常會對地基有影響，因此基礎(chǔ)工程師必須具有足夠的結(jié)構(gòu)設(shè)計方面的知識。

Foundations for structures such as buildings, from the smallest residential to the tallest high-rise, and bridges are for the purpose of transmitting the superstructure loads. These loads come from column-type members with stress intensities ranging from perhaps 140 MPa for?steel to 10 MPa for concrete to the supporting capacity of the soil, which is seldom over 500 kPa but more often on the order of 200 to 250 kPa.

從最小的居住房屋到最高的高層建筑以及橋梁等結(jié)構(gòu)物的基礎(chǔ)都是用來傳遞上部結(jié)構(gòu)荷載的。這種從柱型構(gòu)件傳下的荷載的應力大小，鋼柱約在140 MPa 左右，混凝土柱約為 10 MPa左右。而土的承載能力則很少超過 500kPa，比較常見的是在200 到250 kPa 左右。

Almost any reasonable structure can be built and safely supported if there is unlimited financing. Unfortunately, in the real situation this is seldom, if ever, the case, and the foundation engineer has the dilemma of making a decision under much less than the ideal condition. Also, even though the mistake may be buried, the results from the error are not and can show up relatively soon and probably before any statute of limitations expires. There are reported cases where the foundation defects such as cracked walls or broken mechanical fixtures have shown up years later also cases where the defects have shown up either during construction of the superstructure or immediately thereafter.

對于任何合理的結(jié)構(gòu)物只要有足夠的經(jīng)費，總是可以建造得很安全。不巧的是，如果在實際中有這種情況的話，也是非常少見的，基礎(chǔ)工程師總需要在比理想情況差很多的窘境下作出決定。此外，即使錯誤可以被掩埋，但錯誤造成的后果不會被掩蓋，并且能夠較快地顯示出來—而且可能是在一些法規(guī)所規(guī)定的期限到期之前出現(xiàn)失效。已經(jīng)有過這樣事例報道，基礎(chǔ)的缺陷（例如引起墻體開裂或機械裝置損壞）是在幾年之后才顯示出來的，但是，在有的事例中，基礎(chǔ)的缺陷是在上部結(jié)構(gòu)施工中或緊隨其后顯示出來的。

Since the substructure is buried, or is beneath the superstructure, in such a configuration that access will be difficult should foundation inadequacies develop after the superstructure is in place, it is common practice to be conservative. A one or two percent overdesign in these areas produces a larger potential investment return than in the superstructure.

由于下部結(jié)構(gòu)是埋藏在地下或者是在上部結(jié)構(gòu)的下面，所以在這樣的部位，當上部結(jié)構(gòu)就位之后，如果基礎(chǔ)上的缺陷擴展，那么檢修將很困難，因此通常在設(shè)計上都比較保守。在這些部位保守設(shè)計1% 或2%則會在投資上取得比在上部結(jié)構(gòu)中更大的潛在收益。

The designer is always faced with the question of what constitutes a safe, economical design while simultaneously contending with the inevitable natural soil heterogeneity at a site. Nowadays that problem may be compounded by land scarcity requiring reclamation of areas which have been used as sanitary landfills, garbage dumps, or even hazardous waste disposal areas. Still another complicating factor is that the act of construction can alter the soil properties considerably from those used in the initial analyses/design of the foundation. These factors result in foundation design becoming difficult to quantify that two design firms might come up with completely different designs that?would perform equally satisfactory.?Cost would likely be the?distinguishing feature for the preferred design.?

設(shè)計人員總是面臨如何進行既安全又經(jīng)濟的設(shè)計，而同時又需要與必然存在的工地的自然土壤的不均勻性作斗爭這個問題?，F(xiàn)在這個問題又因為土地稀少，而要利用那些曾被用作垃圾填充的，甚至危險廢料處理區(qū)的土地而復雜化。還有另一個復雜因素是施工作用會改變土性，使其相對它在基礎(chǔ)的初步分析/設(shè)計時發(fā)生顯著的變化。這些因素都使基礎(chǔ)設(shè)計變得難以用數(shù)量來表示，以至于兩個設(shè)計單位會提出完全不同的設(shè)計，但其使用效果可能同樣令人滿意。造價很可能是區(qū)分設(shè)計方案是否被選的主要因素。

This problem and the widely differing solutions would depend, for example, on the following:

(1) What constitutes satisfactory and tolerable settlement; how much extra could, or should, be spent to reduce estimated settlements from say 30 to 15 mm?

(2) Has the client been willing to authorize an adequate soil exploration program? What kind of soil variability did the soil borings indicate? Would additional borings actually improve the foundation recommendations?

(3) Can the building be supported by the soil using

(a) Spread footings-?least cost.

(b) Mats-intermediate in cost.

(c) Piles or caissons-several times the cost of spread footings.

這個問題以及很多不同的解決方案取決于下列各項：

1.滿意和容許的沉降量為多少？如果將預估的沉降量從 30 mm 減少到15mm 應該多花費多少錢？

2.業(yè)主是否愿意授權(quán)進行一項充分的勘察計劃？從鉆孔情況得到的土層變化程度是怎樣的？增加鉆孔是否能切實改進基礎(chǔ)設(shè)計方案？

3.房屋能否用下列基礎(chǔ)支撐：

a.擴展基礎(chǔ)－造價最低；

b.筏板基礎(chǔ)－造價為中等；

c.樁或沉箱－造價為擴展基礎(chǔ)的數(shù)倍。

(4) What are the consequences of a foundation failure in terms of public safety? What is the likelihood of a lawsuit if the foundation does not perform adequately?

(5) Is sufficient money available for the foundation? It is not unheard of that the foundation alone would cost so much the project is not economically feasible. It may be necessary to abandon the site in favor of one where foundation costs are affordable.

(6) What is the ability of the local construction force? It is hardly sensible to design an elaborate foundation if no one can build it, or if it is so different in design that the contractor includes a large?"uncertainty" factor in the bid.

(7) What is the engineering ability of the foundation engineer??While this factor is listed last, this is not of least importance in economical design.?

4.基礎(chǔ)事故會在公共安全方面造成什么后果？如果基礎(chǔ)達不到要求是否會引起訴訟？

5.是否有足夠的經(jīng)費用于基礎(chǔ)？曾經(jīng)有過這種情況，即由于基礎(chǔ)的造價過高而使工程在經(jīng)濟上不可行。因此，需要放棄某一場地而去另選基礎(chǔ)造價能為業(yè)主所能承受的場地。

6.當?shù)厥┕挝坏哪芰θ绾?？如果設(shè)計一個復雜的基礎(chǔ)而沒人能夠施工，或者因為設(shè)計的非常獨特，以致承包商在投標中包含了很多的“不確定性”因素，這都是不明智的。

7.基礎(chǔ)工程師處理工程問題的能力如何？此項目列于最末，但是在經(jīng)濟設(shè)計中并不是一條最不重要的因素。

The foundation engineer must look at the entire system: the?building purpose, probable service-life loading, soil profile, construction methods, and construction costs to arrive at a design that is consistent with the client/owner's needs and does not excessively degrade the environment. This must be done with a safety factor which produces a tolerable risk level to both the public and the owner.

基礎(chǔ)工程師應著眼于整個系統(tǒng)：建筑物的用途，使用年限內(nèi)可能承受的荷載，土層剖面，施工方法及造價，以便使設(shè)計與業(yè)主需要相適應，并且不會對周圍環(huán)境有過多的影響。這就必須使所選取安全系數(shù)產(chǎn)生的風險水平能夠被公眾和業(yè)主所接受。