水利水电工程专业英语教材

范文范例参考

区别清楚。

The primary purpose of each is to obtain a safe coefficient that when exceeded would put the dam in jeopardy of being pushed downstream.每种方法的基本目的都是要求得一个安全系数，当越出此安全系数范围时，坝就有向下游滑动的危险。

The sliding factor of a gravity dam with a horizontal base equals the tangent of the angle between the perpendicular to the base and the resultant foundation reaction. The sliding factor for small dams is computed by taking the ratio of the summation of horizontal forces, to the summation of vertical forces, including the uplift, or

If computed in this manner is equal to or less than the static friction coefficient, the dam is considered safe. A unit width of 1 ft. is assumed for these calculations. Safe values for the sliding factor coefficient are given in table13.1 for various foundation materials.

重力坝具有水平地基面时，其滑动系数等于基面垂线和地基反力合力之间夹角的正切。在小坝上，滑动系数的计算可以取水平力总 和和垂直力总和 （包括扬压力 ），或

如果这种方法求得的 值等于或小于静摩擦系数 ，则认为坝是安全的。计算中假定取单位宽度为1英尺。各种地基材料的滑动系数安全值列表于13.1中。

The factor of safety,, against sliding is defined as the ratio of the coefficient of static friction, to the tangent of the angle between a perpendicular to the base and the direct foundation reaction, expressed as

抗滑安全系数 的定义是静摩擦系数 和地基面垂线与地基反力夹角的正切之间的比值，即 This approach also assumes shear forces as added safety measure. 这个方法也假定剪力为附加安全度。

The safety factor against sliding is usually between 1 and 1.5 for gravity dams on rock utilizing a conservative cross-section. The inclusion of uplift and seismic forces in the calculations may reduce the safety factor to about unity. 对于岩基上断面偏保守的重力坝，抗滑安全系数一般在1～1.5之间。计算中记入扬压力和地震力后，安全系数可降低到接近1。

These values are for safety against sliding on a horizontal plane; if the foundation slopes downstream, the safety factors against sliding on the plane of the base are correspondingly reduced. 这些数值都是指水平面上的抗滑安全系数。如果地基倾向下游，则基面上的抗滑安全系数会相应降低。

Designers often use concrete placed into cutoff s or rock foundations to decrease the sliding tendency of the dam.设计人员经常采取在槽或基岩中浇筑混凝土的办法来减

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范文范例参考

少坝滑动的趋势。

Another approach, favored by many engineers, includes the evaluation of shear into the safety factor. The shear-friction relationship is:

另一个许多工程师乐于采用的方法，是在安全系数中包括剪力的计算。剪摩关系式： Which: is base length at plane of shear being studied; is allowable working shear stress of material or materials at plane of shear.

式中：为所考虑的剪切面上的底宽； 为剪切面上的一种或几种材料的允许工作剪力。 Safety factors computed in this manner should approach values used in normal structural computations. 这种方法算得的安全系数应该接近正常结构计算中使用的数值。

Static friction values often assumed for concrete moving rock or concrete on concrete surfaces varies from 0.65 to 0.75. 对于混凝土和岩石或混凝土之间的滑动，静摩擦系数常假定为0.65～0.75。

The working shear stress of concrete is related to the compressive strength of concrete. 混凝土的工作剪切力 和混凝土的抗压强度有关。

The unit shearing strength of concrete is about one-fifth of the compression breaking stress from standard cylinders. 混凝土的单位剪切强度约为标准圆柱体压缩破坏应力的1/5。

This indicates strength of 400 to 800 psi for concrete in dams. It also provides a safety factor of 4 if the unit working stresses used in computations are 100 to 200 psi. Greater working stresses are not recommended unless the concrete for the smaller dams is actually pretested.对坝体混凝土来说，即为400～800磅/英寸2。如果计算中取工作应力为100～200磅/英寸2，则安全系数还有4。除非小坝的混凝土确实事先做过试验，否则不宜采用更大的工作应力。

4 internal concrete stresses 混凝土的内部应力

The unit stresses in the concrete and foundation materials must be kept within prescribed maximum values to avoid failures. 混凝土和地基材料内的单位应力必须限定在规定的最大值之内，以免引起失事。

Small dams normally develop stresses within the concrete that are less than the actual strength that may develop if the proper concrete mix is used. 如果采用适当的混凝土配合比，则小坝混凝土内引起的应力都小于实有的强度。

A concrete mix that ensures durability will normally have sufficient strength to provide an adequate safety factor against overstressing.一种能保证耐久性的混凝土配合比，通常都具有充分的强度，用以对于抵抗应力超限提供足够的强度。

Overstressing the foundation material must also be investigated. In small dams

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