岩土工程专业知识：冻土的工程性质及地基评价（一）

1、岩土工程专业知识：冻土的工程性质及地基评价（一）    24.4冻土的工程性质及地基评价1 季节性冻土的工程性质及地基评价（1）工程性质：冻土融化后承载力大为降低，压缩性急剧增高，使地基产生融陷；相反，在冻结过程中又产生冻胀，对地基均为不利。冻土的冻胀和融陷与土的颗粒大小及含水量有关，一般土颗粒愈粗，含水量愈小，土的冻胀和融陷性愈小。（2）冻土按冻胀性分类：表24.4-1。季节性冻土的冻胀性分类表24.4-1            &#

2、160;   土的名称            天然含水量W    （）            冻结期间地下水位低于冻深的最小距离（m）            冻胀类别&#

3、160;                   岩石、碎石土、砾砂、粗砂、中砂、细砂            不考虑            不考虑  &#

4、160;         不冻胀                    粉砂            W<14      &#

5、160;     >1.5            不冻胀                    1.5          &

6、#160; 弱冻胀                    14W<19            >1.5             

7、       1.5            冻胀                    W19         

8、0;  >1.5            冻胀                    1.5            强冻胀 &

9、#160;                  粉土            W19            >2.0     &

10、#160;      不冻胀                    2.0            弱冻胀         

11、0;          19<W                 >2.0                    2.

12、0            冻胀                    22<W                &#

13、160;>2.0                    2.0            强冻胀               &

14、#160;    W>26            不考虑                    黏性土           

15、 1OWp+2            >2.0            不冻胀                    2.0  

16、;          弱冻胀                    102+2<WWp+5            >2.0    

17、;                2.0            冻胀                    Wp+5&l

18、t;WWp+9            >2.0                    2.0            强冻胀  

19、0;                 1O>WWp+9            不考虑             注：1、表中碎石土仅指充填物为砂土或硬塑、坚硬状态的黏性土或饱和度不大于0

20、.5的粉土，如充填物为其他状态的黏性土或粉土时，其冻结性应按黏性土或粉土确定。2、表中细砂仅指粒径大于0.075mm的颗粒超过总质量90的细砂，其他细砂的冻胀性应按粉砂确定。3、wp为土的塑限。2 多年冻土的工程性质和地基评价（1）按融沉性分级和评价：多年冻土根据土的类别、总含水量和平均融沉系数0分类（表24.4-2）：多年冻土融沉性分类表24.4-2                 土的名称   

21、0;        总含水量    W0（）            平均融沉    系数0            融沉    等级  

22、60;         融沉    类别            冻土类型                    碎石土，砾、粗、中砂（粒径小于0.07

23、5mm的颗粒含量不大于15）            W0<10            01                      

24、  不融沉            少冰冻土                    W010            03  

25、;                      弱融沉            多冰冻土              

26、0;     碎石土，砾、粗、中砂（粒径小于    0.075mm的颗粒含量大于15）            W0<12            01         

27、0;              不融沉            少冰冻土                    12W0<15 

28、;           1<03                        弱融沉            多冰冻土

29、60;                   15W0<25            3<010               

30、60;        融沉            富冰冻土                    W025        

31、;    10<025                        强融沉            饱冰冻土       &

32、#160;            粉砂、细砂            W0<14            01          

33、0;             不融沉            少冰冻土                    14W0<18  

34、;          1<03                        弱融沉            多冰冻土 

35、60;                  18W0<28            3<010                

36、60;       融沉            富冰冻土                    W028         

37、;   10<025                        强融沉            饱冰冻土        &

38、#160;           粉土            W0<17            01            &

39、#160;           不融沉            少冰冻土                    17W0<21   &#

40、160;        1<03                        弱融沉            多冰冻土   

41、                 21W0<32            3<010                  

42、      融沉            富冰冻土                    W032          &#

43、160; 10<025                        强融沉            饱冰冻土         

44、0;          粘性土                              01         

45、;               不融沉            少冰冻土                    WpW0<WP

46、+4< FONT>            1<03                        弱融沉            多冰冻土