土力学某次课堂习题精要.ppt

习题 Example 2: The soil profile at a site for a proposed office building consists of a layer of fine sand 10.4 m thick above a layer of soft normally consolidated clay 2 m thick. Below the soft clay is a deposit of coarse sand. The groundwater table was observed at 3 m below ground level. The void ratio of the sand is 0.76 and the water content of the clay is 43%. The building will impose a vertical stress increase of 140 kPa at the middle of the clay layer. Estimate the primary consolidation settlement of the clay. Assume the soil above the water table to be saturated, Cc 0.3 and Gs 2.7. Strategy Calculate initial stress and void ratio at the center of the clay layer Calculate the increase of stress at the mid-depth of the clay layer Calculate the final stress Calculate the settlement Example 3: Assume the same soil stratigraphy as in Example 2. But now the clay is over-consolidated with an OCR 2.5, w 38%, and Ce 0.05. All other soil values given in Example remain unchanged. Determine the primary consolidation settlement of the clay. Since the soil is overconsolidated, we will have to check whether the preconsolidation stress is less than or greater than the sum of the current vertical effective stress and the applied vertical stress at the center of the clay. This check will determine the appropriate equation to use. In this problem, the unit weight of the sand is unchanged but the clay has changed. Example 4: Assume the same soil stratigraphy as in Example 2. But now the clay is over-consolidated with an OCR 1.5, w 38%, and Ce 0.05. All other soil values given in Example remain unchanged. Determine the primary consolidation settlement of the clay. 某饱和粘土层的厚度为10m，在大面积荷载p0＝120kpa作用下，土层的初始孔隙比e 1.0，压缩系数a 0.3MPa-1，渗透系数k 18mm/y。按粘土层在单面或双面排水条件下分别求（1）加荷一年时的沉降量；（2）沉降量达140mm所需的时间。 某砂土试样进行三轴固结不排水试验，施加的围压为200kPa。试样破坏时的轴向偏应力为240kPa，已知土的内摩擦角为30度，求（1）破坏时的孔隙水压力（2）破裂面上的法向应力和剪应力，以及该面与水平面的夹角；（3）若该试样在同样的围压下进行固结排水剪切试验，求破坏时的轴向应力。 * 某土样在法向应力 作用下进行直剪试验，测得其抗剪强度 在法向应力 作用下进行直剪试验，测得其抗