3.下列哪种方法不适用于砂性土的碎石桩施工

A.振冲挤密法                                                             B.沉管法

C.置换法                                                                      D.干振法

4.在塑料排水板加固地基时，在地面上铺筑砂砾垫层主要是为了

A.提高地基承载力                                                     B.排水

C.施工需要                                                                  D.扩散路基应力

5.次固结沉降是由土骨架的____应力产生的骨架蠕变变形。

A.有效                                                                          B.总

C.剪应力                                                                      D.拉应力

6.真空预压法中，采用真空泵抽气后，土中产生____孔隙水压力，土体固结，地基强度提高。

A.正                                                                              B.负

C.零                                                                              D.以上均有可能

7.土工合成材料用作土体加筋时，其基本作用是给土体提供

A.抗剪强度                                                                  B.抗弯强度

C.抗拉强度                                                                  D.抗压强度

8.水泥搅拌桩是采用____方式提高了地基的稳定性。

A.排水