Liquefaction of saturated sand deposits under nonuniform vertical stresses

Liquefaction of saturated sand deposits under nonuniform vertical stresses

Creators Yamamoto Tetsuro

Creators Ohara Sukeo

Creators Ishikawa Mitsuo

In order to clarify the characteristics of liquefaction and liquefaction-induced settlement of saturated sand deposits of which the vertical stresses are different partially such as those below and near overburden structures, a series of shaking table tests are performed on the model sand layer prepared in three Kjellman's type simple shear boxes. The model sand layer consists of three saturated sand layers of which the effective vertical stresses σ'_<vo> are 10.4kPa, 30.0kPa and 49.6kPa respectively, and is called model (1) hereafter. Also, the same tests are carried out on four models (2) to (5) consisting of two sand layers having different RVS-values. Here RVS=(σ'_<vo>)_s / (σ'_<vo>)_1, in which (σ'_<vo>)_s and (σ'_<vo>)_1 represent lower and higher vertical stresses of two respective sand layers. It is found from the tests that in the case of seismic coefficient k_h≧0.15, irrespective of the RVS-values and in the case of k_h<0.15 and RVS≧0.5, all sand layers of the models liquefied almost simultaneously. On the contrary, in the case of k_h<0.15 and RVS<0.5, the sand layer of (σ'_<vo>)_s liquefied easily due to the effect of pore water pressure induced in the sand layer of (σ'_<vo>)_1, though the sand layer of (σ'_<vo>)_1 didn't occur to liquefy. Namely, it was concluded that the liquefaction characteristics of such model sand layers were affected by the RVS-value and the acceleration level of vibration. Furthermore, it is shown that the amount of the liquefaction-induced settlement of the model sand layer increases remarkably in the range of lower vertical stresses and takes almost a constant value as the vertical stresses increase.

[ISSN]0386-3433

[NCID]AA0086073X