我不懂岩土，所以不知道一些词汇应如何用术语翻译。但我把大致意思译一下，希望有帮助。
1、A slope failure can reasonably be considered as a full scale shear test （capable to give a measure of the strength） mobilized at failure along the slip surface.
当（能测量强度的）满量程剪力测试在滑动表面的损坏处移动时，便有足够的理由认定为坡面损坏。
2、The principle of the proposed approach is illustrated in Fig.12 which gives the driving and resisting force 〔acting （on each pile in a row） as a function （of the non-dimensional pile interval ratio B/D）〕.
句子分析：which后面引导了一个定语从句修饰Fig. 12。在这个成分内部，acting as a funcion 是现在分词短语作the driving and resisting force 的定语。）
翻译：所提出的方法的原理阐释请见图12。该图给出了〔（以无维度堆间间隔比率B/D方式）作用（于一行中每一堆）的〕驱动力和阻力。
3、Moreover progressive failure or softening 〔resulting in strength reductions （that are different from a point to the other）〕, can render heterogeneous even deposits before homogeneous. （主要是后半句不知怎么翻译）
而且，逐渐的损坏或软化〔导致（各点程度不同的）强度降低〕，会使得均匀矿床在同质化之前异质化。