土壌硬度を指標とした地山しらすの安定勾配の評価に関する検討

抄録

In order to establish the method to estimate the stability of the Shirasu slope, relationships between soil hardness and physical properties, and strength characteristics of Shirasu were examined.
As a result, the facts mentioned below were made clear.
1) Soil hardness value measured by the Yamanaka-type Soil Hardness Tester is more fitted than Nc-value measured by the conventional penetrometers for slope survey to estimate the strength characteristics of the undisturbed Shirasu because of the small penetration energy.
2) Because of the initial structural anisotropy, soil hardness value measured in a horizontal direction is larger than that measured in a vertical direction.
3) The density of soil particles and the particle size distribution is almost same even if soil hardness value of the undisturbed Shirasu is different, while the void ratio, the unit weight of the undisturbed Shirasu is different when soil hardness is changing.
4) Relationships between soil hardness value and the value of C_d, φ_d by CD triaxial compression test is very clear.
5) Relationship between soil hardness value and the measured slopes of actual slip surface is well simulated when stable slope is calculated using relationships between soil hardness value and physical, strength properties of Shirasu.