[求助]计算时侧压力系数如何取值 [复制链接]

在用有限元计算的时候，有两种情况，一是采用地层荷载法计算相应的土压力，土的侧压力采用朗肯土压力可以算出，土质越差，侧压力系数一般越大。另一种方法是采用地层结构法，是有限元自动将土压力叠加进去，侧压力系数此时一般为垂直压力与水平压力的比值，这个时候一般取多大呢，如果按照上面的朗肯理论，好像非常不妥，比如说埋深100m,此时水平压力与垂直压力大致相等.这两个好像都叫侧压力系数，取值时一般怎么取呢，请高手指点。谢谢

Actually you talk about K0 value, my understanding is:

1) Cohesiveless soil,  for example, the sand or some  granular material , you can use Rankine theory to calculate this K0 value, but it is only for Normal Consolidated soil in primary loading path. In reality, most cases are OC (over consolidated),  there is a equation

K0(OC)=f(K0, OCR)=(1-sin(phi)){[OCR/OCRmax^(1-sin(phi))]+0.73*(1-OCR/OCRmax)};

for primary loading: K0=(1-sin(phi))OCR^(sin(phi))

In unloading/reloading path, the K0 value is bigger if you have excavation or backfill.

2)Cohesive soil, such as clay, some empirical equation(relate to PI(plasitic index))
    K0(NC)=f(PI)
    Such as: K0 (NC)=0.19+0.233log(PI)    (Alpan 1967)

3) If the depth is about 100 meter, the response of soil is linear elastic, the soil here is not the same as the normal soil we discussed above.  Rankine theory is not suitable here. In finite element, the Poisson's ratio will control this.

good！good！

有没有关于岩层的解释呢~