When mobilizing shear strength of soil using passive pressure, which is true about the wall's movement?

When mobilizing the shear strength of soil using passive pressure, the correct relationship involves the wall moving into the soil. This inward movement is crucial because, as the wall displaces soil, it engages the soil particles, thereby generating passive resistance.

When the wall moves towards the soil, it compresses the soil and causes it to mobilize its shear strength, which is fundamentally a response to being forced to reorganize due to the wall's movement. This action allows for the creation of passive earth pressure, which is a result of the soil's ability to resist deformation in response to the wall's intrusion. This is in direct contrast to the other choices, which do not reflect the physical mechanics at play in this context.

Movement outward does not facilitate the necessary engagement of soil for passive resistance to occur. If the wall was to remain stationary, there would be no mobilization of shear strength since no displacement is occurring. Vibration would also not serve the intended purpose of effectively mobilizing passive resistance, as it lacks a controlled mechanism for engaging soil strength in a constructive manner. Thus, the correct understanding of wall movement in relation to soil passive pressure is characterized by the wall moving into the soil.