He had to rely on whatever books were lying around.
He knew nothing whatever about it.
There is no scientific evidence whatever to support such a view.

句(1),感觉好别扭,不知该如何断句和理解?
句(2)(3)里,介词汇短语前都多了个whatever,该如何理解句子的意思,还是定语吗?

He had to rely on whatever books were lying around.
He knew nothing whatever about it.
There is no scientific evidence whatever to support such a view.

以上三句都正确。

句(1)whatever 是融合型关系限定词,引导名词性关系分句。whatever 没疑问含义。分句等于一个名词词组。

whatever books were lying around = any books thatwere lying around (任何在周围的书本)

句(2)和(3)whatever 是用来强调否定的副词,意为“任何;丝毫”。用于名词性词组(包含不定代词)后,强调否定陈述。跟 at all 的使用方法类似,可以省去。

He knew nothing about it.
There is no scientific evidence to support such a view.

【翻译】

(1)他不能不依赖阅读身边周围的书本。

(2)他对此一无所知

(3)没任何证据表明,广播业的角逐使本钱有所减少。